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#1876 2023-08-21 00:04:44

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1880) Senior Citizen


Observed every year on August 21, World Senior Citizen Day is celebrated in recognition of the contributions made by the elderly to society.


Old age is the range of ages for persons nearing and surpassing life expectancy. People of old age are also referred to as: old people, elderly, elders, seniors, senior citizens, or older adults.

Old age is not a definite biological stage: the chronological age denoted as "old age" varies culturally and historically. Some disciplines and domains focus on the aging and the aged, such as the organic processes of aging (senescence), medical studies of the aging process (gerontology), diseases that afflict older adults (geriatrics), technology to support the aging society (gerontechnology), and leisure and sport activities adapted to older people (such as senior sport).

Old people often have limited regenerative abilities and are more susceptible to illness and injury than younger adults. They face social problems related to retirement, loneliness, and ageism.

In 2011, the United Nations proposed a human-rights convention to protect old people.


Definitions of old age include official definitions, sub-group definitions, and four dimensions as follows.

Official definitions

Most developed Western countries set the retirement age around the age of 65; this is also generally considered to mark the transition from middle to old age. Reaching this age is commonly a requirement to become eligible for senior social programs. In non-Western nations, old age can begin as early as the mid-40s or as late as the 70s, although the idea of 'old age' generally shifts around.

Old age cannot be universally defined because it is context-sensitive. The United Nations, for example, considers old age to be 60 years or older. In contrast, a 2001 joint report by the U.S. National Institute on Aging and the World Health Organization [WHO] Regional Office for Africa set the beginning of old age in Sub-Saharan Africa at 50. This lower threshold stems primarily from a different way of thinking about old age in developing nations. Unlike in the developed world, where chronological age determines retirement, societies in developing countries determine old age according to a person's ability to make active contributions to society. This number is also significantly affected by lower life expectancy throughout the developing world.

Sub-group definitions

Gerontologists have recognized that people experience very different conditions as they approach old age. In developed countries, many people in their later 60s and 70s (frequently called “early old age”) are still fit, active, and able to care for themselves.  However, after 80, they generally become increasingly frail, a condition marked by serious mental and physical debilitation.

Therefore, rather than lumping together all people who have been defined as old, some gerontologists have recognized the diversity of old age by defining sub-groups. One study distinguishes the young-old (60 to 69), the middle-old (70 to 79), and the very old (80+).[16] Another study's sub-grouping is young-old (65 to 74), middle-old (75 to 84), and oldest-old (85+). A third sub-grouping is young-old (65 to 74), old (74 to 84), and old-old (85+). Describing sub-groups in the 65+ population enables a more accurate portrayal of significant life changes.

Two British scholars, Paul Higgs and Chris Gilleard, have added a "fourth age" sub-group. In British English, the "third age" is "the period in life of active retirement, following middle age". Higgs and Gilleard describe the fourth age as "an arena of inactive, unhealthy, unproductive, and ultimately unsuccessful ageing".


Key Concepts in Social Gerontology lists four dimensions: chronological, biological, psychological, and social.  Wattis and Curran add a fifth dimension: developmental. Chronological age may differ considerably from a person's functional age. The distinguishing marks of old age normally occur in all five senses at different times and at different rates for different people. In addition to chronological age, people can be considered old because of the other dimensions of old age. For example, people may be considered old when they become grandparents or when they begin to do less or different work in retirement.

Senior citizen

Senior citizen is a common euphemism for an old person used in American English, and sometimes in British English. It implies that the person being referred to is retired. This in turn usually implies that the person is over the retirement age, which varies according to country. Synonyms include old age pensioner or pensioner in British English, and retiree and senior in American English. Some dictionaries describe widespread use of "senior citizen" for people over the age of 65.

When defined in a legal context, senior citizen is often used for legal or policy-related reasons in determining who is eligible for certain benefits available to the age group.

It is used in general usage instead of traditional terms such as "old person", "old-age pensioner", or "elderly" as a courtesy and to signify continuing relevance of and respect for this population group as "citizens" of society, of senior "rank".

The term was apparently coined in 1938 during a political campaign. Famed caricaturist Al Hirschfeld claimed on several occasions that his father Isaac Hirschfeld invented the term "senior citizen". It has come into widespread use in recent decades in legislation, commerce, and common speech. Especially in less formal contexts, it is often abbreviated as "senior(s)", which is also used as an adjective.

Age qualifications

The age of 65 has long been considered the benchmark for senior citizenship in numerous countries. This convention originated from Chancellor Otto von Bismarck's introduction of the pension system in Germany during the late 19th century. Bismarck's legislation set the retirement age at 70, with 65 as the age at which individuals could start receiving a pension. This age standard gradually gained acceptance in other nations and has since become deeply entrenched in public consciousness.

The age which qualifies for senior citizen status varies widely. In governmental contexts, it is usually associated with an age at which pensions or medical benefits for the elderly become available. In commercial contexts, where it may serve as a marketing device to attract customers, the age is often significantly lower.

In commerce, some businesses offer customers of a certain age a "senior discount". The age at which these discounts are available varies from 55, 60, 62 or 65 upwards, and other criteria may also apply. Sometimes a special "senior discount card" or other proof of age needs to be produced to show entitlement.

In the United States, the standard retirement age is currently 66 (gradually increasing to 67). The AARP allows couples in which one spouse has reached the age of 50 to join, regardless of the age of the other spouse.

(AARP (formerly called the American Association of Retired Persons) is an interest group in the United States focusing on issues affecting those over the age of fifty. The organization said it had more than 38 million members in 2018. The magazine and bulletin it sends to its members are the two largest-circulation publications in the United States.)

AARP was formed in 1958 by Ethel Percy Andrus, a retired educator from California, and Leonard Davis, who later founded the Colonial Penn Group of insurance companies. It is an influential lobbying group in the United States. AARP sells paid memberships, and markets insurance and other services to its members.

In Canada, the Old Age Security (OAS) pension is available at 65 (the Conservative government of Stephen Harper had planned to gradually increase the age of eligibility to 67, starting in the years 2023–2029, although the Liberal government of Justin Trudeau is considering leaving it at 65), and the Canada Pension Plan (CPP) as early as age 60.


The distinguishing characteristics of old age are both physical and mental. The marks of old age are so unlike the marks of middle age that legal scholar Richard Posner suggests that, as an individual transitions into old age, that person can be thought of as different people "time-sharing" the same identity.

These marks do not occur at the same chronological age for everyone. Also, they occur at different rates and order for different people. Marks of old age can easily vary between people of the same chronological age.

A basic mark of old age that affects both body and mind is "slowness of behavior". The term describes a correlation between advancing age and slowness of reaction and physical and mental task performance. However, studies from Buffalo University and Northwestern University have shown that the elderly are a happier age group than their younger counterparts.


Physical marks of old age include the following:

* Bone and joint problems: Old bones are marked by "thinning and shrinkage". This might result in a loss of height (about two inches (5 cm) by age 80), a stooping posture in many people, and a greater susceptibility to bone and joint diseases such as osteoarthritis and osteoporosis.
* Chronic diseases: Some older people have at least one chronic condition and many have multiple conditions. In 2007–2009, the most frequently occurring conditions among older people in the United States were uncontrolled hypertension (34%), arthritis (50%), and heart disease (32%).
* Chronic mucus hypersecretion (CMH), defined as "coughing and bringing up sputum", is a common respiratory symptom in elderly people.
* Dental problems: Older people may have less saliva and reduced ability to maintain oral hygiene, consequently increasing the chance of tooth decay and infection.
* Digestive system issues: About 40% of the time, old age is marked by digestive disorders such as difficulty in swallowing, inability to eat enough and to absorb nutrition, constipation and bleeding.
* Essential tremor (ET): An uncontrollable shaking in a part of the upper body. It is more common in the elderly and symptoms worsen with age.
* Eyesight deterioration: Presbyopia can occur by age 50 and it hinders reading, especially of small print in low lighting. The speed with which an individual reads and the ability to locate objects may also be impaired. By age 80, more than half of all Americans either have a cataract or have had cataract surgery.
* Falls: Old age increases the risk of injury from falls. Every year, about a third of those 65 years old and more than half of those 80 years old fall. Falls are the leading cause of injury and death for old people.
* Gait change: Some aspects of gait normally change with old age. Speed slows after age 70. Time with both feet on the ground ("double stance") increases. Old people sometimes move as if they were walking carefully on ice.
* Hair usually turns gray and may become thinner. About age 50, about 50% of Europeans have 50% grey hair. Many men are affected by balding.
* Women enter menopause.
* Hearing loss: By age 75, 48% of men and 37% of women have lost at least some significant hearing. Of the 26.7 million people  over age 50 with a hearing impairment, one seventh use hearing aids. In the 70–79 age range, partial hearing loss affecting communication rises to 65%, mostly in low-income men.
* Hearts can become less efficient in old age, lessening stamina. Atherosclerosis can constrict blood flow.
* Immune-function loss (Immunosenescence).
* Lungs may expand less efficiently, providing less oxygen.
* Mobility impairment or loss: "Impairment in mobility affects 14% of those between 65 and 74, [and] half of those over 85." Loss of mobility is common in old people and has serious "social, psychological, and physical consequences".
* Pain: 25% of seniors have chronic pain, increasing with age, up to 80% of those in nursing homes. Most pains are rheumatological or malignant.
* Decreases in sexual drive in both men and women. Increasing research on sexual behavior and desires in later life is challenging the "asexual" image of older adults. People aged 75–102 do experience sensuality and sexual pleasure. Sexual attitudes and identity are established in early adulthood and change little. Sexuality remains important throughout life, and the sexual expression of "typical, healthy older persons is a relatively neglected topic of research".
* Skin loses elasticity and gets drier and more lined and wrinkled.
* Wounds take longer to heal and are likelier to leave permanent scars.
* Trouble sleeping and daytime sleepiness affect more than half of seniors. In a study of 9,000 people with a mean age of 74, only 12% reported no sleep complaints. By age 65, deep sleep drops to about 5% of sleep time.
* Taste buds diminish by up to half by the age of 80. Food becomes less appealing and nutrition can suffer.
* Over the age of 85, thirst perception decreases, so that 41% of the elderly don't drink enough.
* Urinary incontinence is often found in old age.
* Vocal cords weaken and vibrate more slowly. This results in a weakened, breathy voice, "old person's voice".


Mental marks of old age include the following:

* Agreeability: Despite the stressfulness of old age, the words "agreeable" and "accepting" are used commonly to describe people of old age. However, in some people, the dependence that comes with old age induces feelings of incompetence and worthlessness from having to rely on others for many different basic living functions.
* Caution follows closely with old age. This antipathy toward "risk-taking" often stems from the fact that old people have less to gain and more to lose than younger people.
* Depressed mood. According to Cox, Abramson, Devine, and Hollon (2012), old age is a risk factor for depression caused by prejudice. When younger people are prejudiced against the elderly and then become old themselves, their anti-elderly prejudice turns inward, causing depression. "People with more negative age stereotypes will likely have higher rates of depression as they get older." 
* Fear of crime in old age, especially among the frail, sometimes weighs more heavily than concerns about finances or health and restricts what they do. The fear persists in spite of the fact that old people are victims of crime less often than younger people.
* Increasing fear of health problems.
* Mental disorders affect about 15% of people aged 60+ according to estimates by the World Health Organization. Another survey taken in 15 countries reported that mental disorders of adults interfered with their daily activities more than physical problems.
* Reduced mental and cognitive ability: Memory loss is common in old age due to the brain's decreased ability to encode, store, and retrieve information. It takes more time to learn the same amount of new information. The prevalence of dementia increases in old age from about 10% at age 65 to about 50% over age 85. Alzheimer's disease accounts for 50 to 80 percent of dementia cases. Demented behavior can include wandering, physical aggression, verbal outbursts, depression, and psychosis.
* Stubbornness: A study of over 400 seniors found a "preference for the routine". Explanations include old age's toll on "fluid intelligence" and the "more deeply entrenched" ways of the old.

Additional Information

Old age, also called senescence, in human beings, is the final stage of the normal life span. Definitions of old age are not consistent from the standpoints of biology, demography (conditions of mortality and morbidity), employment and retirement, and sociology. For statistical and public administrative purposes, however, old age is frequently defined as 60 or 65 years of age or older.

Old age has a dual definition. It is the last stage in the life processes of an individual, and it is an age group or generation comprising a segment of the oldest members of a population. The social aspects of old age are influenced by the relationship of the physiological effects of aging and the collective experiences and shared values of that generation to the particular organization of the society in which it exists.

There is no universally accepted age that is considered old among or within societies. Often discrepancies exist as to what age a society may consider old and what members in that society of that age and older may consider old. Moreover, biologists are not in agreement about the existence of an inherent biological cause for aging. However, in most contemporary Western countries, 60 or 65 is the age of eligibility for retirement and old-age social programs, although many countries and societies regard old age as occurring anywhere from the mid-40s to the 70s.

Social programs

State institutions to aid the elderly have existed in varying degrees since the time of the ancient Roman Empire. England in 1601 enacted the Poor Law, which recognized the state’s responsibility to the aged, although programs were carried out by local church parishes. An amendment to this law in 1834 instituted workhouses for the poor and aged, and in 1925 England introduced social insurance for the aged regulated by statistical evaluations. In 1940 programs for the aged came under England’s welfare state system.

In the 1880s Otto von Bismarck in Germany introduced old-age pensions whose model was followed by most other western European countries. Today more than 100 nations have some form of social security program for the aged. The United States was one of the last countries to institute such programs. Not until the Social Security Act of 1935 was formulated to relieve hardships caused by the Great Depression were the elderly granted old-age pensions. For the most part, these state programs, while alleviating some burdens of aging, still do not bring older people to a level of income comparable to that of younger people.

Physiological effects

The physiological effects of aging differ widely among individuals. However, chronic ailments, especially aches and pains, are more prevalent than acute ailments, requiring older people to spend more time and money on medical problems than younger people. The rising cost of medical care has caused a growing concern among older people and societies, in general resulting in constant reevaluation and reform of institutions and programs designed to aid the elderly with these expenses.

In ancient Rome and medieval Europe the average life span is estimated to have been between 20 and 30 years. Life expectancy today has expanded in historically unprecedented proportions, greatly increasing the numbers of people who survive over the age of 65. Therefore, the instances of medical problems associated with aging, such as certain kinds of cancer and heart disease, have increased, giving rise to greater consideration, both in research and in social programs, for accommodating this increase.

Certain aspects of sensory and perceptual skills, muscular strength, and certain kinds of memory tend to diminish with age, rendering older people unsuitable for some activities. There is, however, no conclusive evidence that intelligence deteriorates with age, but rather that it is more closely associated with education and standard of living. Sexual activity tends to decrease with age, but if an individual is healthy there is no age limit for its continuance.

Many of the myths surrounding the process of aging are being invalidated by increased studies in gerontology, but there still is not sufficient information to provide adequate conclusions.

Demographic and socioeconomic influences

In general the social status of an age group is related to its effective influence in its society, which is associated with that group’s function in productivity. In agrarian societies the elderly have a status of respectability. Their life experiences and knowledge are regarded as valuable, especially in preliterate societies where knowledge is orally transmitted. The range of activities in these societies allows the elderly to continue to be productive members of their communities.

In industrialized nations the status of the elderly has altered as the socioeconomic conditions have changed, tending to reduce the status of the elderly as a society becomes more technologically oriented. Since physical disability is less a factor in productive capability in industrialized countries, this reduction in social status is thought to have been generated by several interrelated factors: the numbers of still able-bodied older workers outstripping the number of available employment opportunities, the decline in self-employment which allows a worker to gradually decrease activity with age, and the continual introduction of new technology requiring special training and education.

Although in certain fields old age is still considered an asset, particularly in the political arena, older people are increasingly being forced into retirement before their productive years are over, causing problems in their psychological adaptations to old age. Retirement is not regarded unfavourably in all instances, but its economic limitations tend to further remove older people from the realm of influence and raise problems in the extended use of leisure time and housing. As a consequence, financial preparation for retirement has become an increased concern for individuals and society.

Familial relationships tend to be the focus of the elderly’s attention. However, as the family structure in industrialized countries has changed in the past 100 years from a unit encompassing several generations living in close proximity to self-contained nuclear families of only parents and young children, older people have become isolated from younger people and each other. Studies have shown that as a person ages he or she prefers to remain in the same locale. However, the tendency for young people in industrialized countries to be highly mobile has forced older people to decide whether to move to keep up with their families or to remain in neighbourhoods which also change, altering their familiar patterns of activity. Although most older people do live within an hour from their closest child, industrialized societies are faced with formulating programs to accommodate increasing numbers of older people who function independently of their families.

A significant factor in the social aspects of old age concerns the values and education of the generation itself. In industrialized countries especially, where changes occur more rapidly than in agrarian societies, a generation born 65 years ago may find that the dominant mores, expectations, definitions of the quality of life, and roles of older people have changed considerably by the time it reaches old age. Formal education, which usually takes place in the early years and forms collective opinions and mores, tends to enhance the difficulties in adapting to old age. However, resistance to change, which is often associated with the elderly, is being shown to be less an inability to change than a trend in older people to regard life with a tolerant attitude. Apparent passivity may actually be a choice based on experience, which has taught older people to perceive certain aspects of life as unchangeable. Adult education programs are beginning to close the generation gap; however, as each successive generation reaches old age, bringing with it its particular biases and preferences, new problems arise requiring new social accommodations.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1877 2023-08-22 00:40:53

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1881. Stammer


Stammer is to speak with difficulty, repeating sounds and pausing before saying things correctly.

Stuttering — also called stammering or childhood-onset fluency disorder — is a speech disorder that involves frequent and significant problems with normal fluency and flow of speech. People who stutter know what they want to say, but have difficulty saying it.


Stammering is when someone repeats, prolongs or gets stuck when trying to say sounds or words. There might also be signs of visible tension as the person works hard to get the word out. But it is different from the occasional repetition that everybody experiences.

We don't know exactly what causes stammering, but research is showing that it is neurological. This means that the way speech is produced in the brain is different for people who stammer. Stammering is the way some people talk. That's all.

Stammering Facts

* About 8% of children will stammer at some point. For the majority of children this will be temporary.   
* Up to 2%* of people will stammer into adulthood. This figure has historically been thought to be 1%. We have updated it following our 2021 YouGov polling.
* Stammering can run in families. Around 60% of people who stammer have a relative who stammers or used to stammer.
* In the UK we largely use the term stammering. Other countries call it stuttering. But it means the same thing.
* More men than women stammer.
* People of all ethnicities can stammer.
* People do not stammer because they are less intelligent. It has nothing to do with personality types either.
* Like other neurological conditions, it covers a spectrum. Everyone stammers differently and to different degrees.
* Stammering is variable. People can stammer less on some days and more on others. They might also have periods in their life when they stammer less, and periods when they stammer more.
* Many find that as they get older, they stammer less.
* You might not even know that a person stammers. Some people use methods and strategies to mask their stammering, so that it is less obvious to others.


The Experience Of Stammering

The physical act of stammering can be a tiny part of the experience. Growing up with a stammer, anticipating times when you'll need to talk, the negative responses, the ever-present expectation that you need fixing or need to breathe properly. Feelings of shame, embarrassment, anger, anxiety and fear. Frustration that saying one's name — the one thing that most people who stammer will find hard to say — will stymie your every encounter. The frustration of not being taken seriously. For many people who stammer it is this aspect of having a stammer which forms the greater part of the experience, and there are many people out there who swap words, avoid contact, keep silent, so that people don't know that they stammer.

Stammering is variable. A stammer can change from one day, hour or sentence, to the next. The daily impact of this can be disempowering: to literally have the ability to take an active part in conversations or even order a coffee, be taken away by a physical disability.

There are all kinds of options for people who stammer, and we'll try and cover them on this site.

Physically, stammering can be deeply frustrating, but the main problem, time and again, is other people's responses.


Stammering has been used as a device to make people laugh and to indicate dishonesty or low intelligence. This stereotyping, and the frustration caused by the difficulty of talking with others, has led many to avoid stammering and find ways of sounding 'normal'.

You may know someone who stammers 'a little', or be surprised to hear that someone you know well tells you that they stammer. Societal expectations mean that people will often try to avoid stammering. They will anticipate speaking situations and plan for them. They may swap a word they expect to stammer on. Or they may keep what they say to the bare minimum. They may arrive late to a meeting to avoid introducing themselves.

Because stammering has very little visibility in public life, people's reaction when they hear a stammer can take many inappropriate forms, and people often misunderstand why someone appears to stumble when they talk, assuming it's nerves or that the person is drunk or unwell.

Additional Information

Stuttering or stammering is a problem of speech. It is a speech disorder some people have. Five to six percent of children have a stammer while one percent of adults have a stammer. Men are four times more likely to have a stammer than women. Stammers normally start at 2-6 years and run in families.

The person knows what they want to say but the flow of their speech is ‘bumpy’ and may have some of the following features:

* Repetitions (of sounds, parts of words or phrases)
* Blocks (stops before words)
* Prolongations (making a sound longer, e.g. 'hhhhhhham' instead of 'ham')
* Pauses
* Rephrasing (saying something else instead)
* Hesitations (struggling to say words)
* Fillers (using key phrases such as ‘you know what I mean’ to hide their difficulties)
* Tension (the muscles in their face and neck look tight)
* Facial or body movements
* Feelings and attitudes

Stammering can be very upsetting, and knock a person's confidence. Joseph Sheehan compared stuttering to an iceberg, with the bumpy parts you can hear (overt parts) of stuttering above the waterline, and the larger block of how the person feels (covert parts) invisible below the surface. These people may feel embarrassment, shame, frustration, fear, anger, and guilt. These feelings may increase stress and effort making the person stammer more. Such negative feelings may be an important part of a treatment program. Stammers affect peoples lives. They may lack confidence to apply for job interviews or make friends.

Additional Information

Stuttering, also called stammering or dysphemia, is a speech defect characterized by involuntary repetition of sounds or syllables and the intermittent blocking or prolongation of sounds, syllables, and words. These disruptions alter the rhythm and fluency of speech and sometimes impede communication, with consequences on the affected individual’s confidence when speaking. About 1 percent of adults and 5 percent of children between ages two and five stutter. In Western countries stuttering is three to four times more common in boys than in girls.

Stutterers consistently have difficulty with certain types of words: those beginning with consonants, initial words in sentences, content words (nouns, verbs, adjectives; as opposed to function words, such as pronouns and prepositions), and words of several syllables. Since these are also the types of words that produce hesitation in normal speakers, there seems to be some link between stuttering and normal disfluency (pauses, repetition).

The causes of stuttering are unclear, although various factors have been implicated. For example, stuttering tends to run in families, indicating that genetics may contribute in part to its development. Researchers suspect that persons who are genetically predisposed to stuttering may be more susceptible to environmental factors, such as stress or excitement, that trigger stuttering than persons who do not have a family history of the disorder.

Three primary forms of stuttering have been described: developmental, neurogenic, and psychogenic. Developmental stuttering occurs in young children and typically manifests when a child is first learning to speak but lacks the speech and language skills necessary to express himself or herself through speech. In this instance stuttering may be precipitated by excitement, stress, or anxiety. For most children developmental stuttering is temporary, with recovery occurring within four years of symptom onset.

Neurogenic stuttering is defined by abnormalities in signaling between the brain and the nerve fibres and muscles controlling speech. This form of stuttering is associated with structural damage in the motor speech area of the brain. Damage to this area may occur as a result of stroke or other forms of brain trauma or in rare cases as a result of congenital defects of the brain.

Psychogenic stuttering is a rare condition that appears to occur almost exclusively in individuals who have experienced severe emotional trauma or who have a history of psychiatric illness. This form of stuttering is characterized primarily by the rapid repetition of initial word sounds.

Between 75 and 80 percent of children who stutter recover spontaneously. Recovery is probably the result of increased self-esteem, acceptance of the problem, and consequent relaxation. When stuttering persists, the condition may require diagnosis and treatment by a speech-language pathologist, who is trained to discern even minor disfluencies in speech that may underlie stuttering. Treatment frequently entails speech therapy, such as controlled fluency with self-monitoring of stuttering. Parental involvement, particularly with regard to ensuring a relaxed speaking environment and slow speech, plays an important supportive role in stuttering therapy.

Most adult stutterers can predict many of the words they will stutter in reading aloud a given passage. Supposedly taking their cue from past difficulties, they anticipate difficulty with certain words and avoid their use, instead relying on word substitutions and other forms of speech and sentence revision.

Throughout history a number of prominent individuals, including writers, orators, and actors, have been affected by stuttering in either childhood or adulthood. Included among these individuals are English novelist Lewis Carroll, King George VI of the United Kingdom, humanitarian and founder of the American Red Cross Clara Barton, and American actor Bruce Willis.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1878 2023-08-23 01:03:29

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1882) Beta blocker


Beta-blocker, in full beta-adrenergic blocking agent, is any of a group of synthetic drugs used in the treatment of a wide range of diseases and conditions of the sympathetic nervous system. Stimulation by epinephrine of beta-adrenoreceptors, which are predominately found in cells of the heart and also are present in vascular and other smooth muscles, results in excitation of the sympathetic nervous system. Beta-blockers diminish reaction at the beta-adrenoreceptors, thereby preventing or decreasing excitation. The drugs are prescribed to control anxiety and hypertension and to treat a variety of cardiac conditions, including angina pectoris and cardiac arrythmias. They are also used in the treatment of glaucoma and to reduce the incidence of migraine headaches. The drugs have proved to be successful in reducing a person’s risk of a second heart attack.


What are beta-blockers?

Beta-blockers are a class of medication used to block the effects of stress hormones such as adrenaline on the heart. They’re often prescribed for irregular heartbeat, high blood pressure, and after heart attacks.

Less commonly, beta-blockers may be used to treat:

* glaucoma
* migraine
* anxiety disorders
* hyperthyroidism
* tremors

Doctors typically turn to beta-blockers for high blood pressure when other medications, such as diuretics, aren’t working or have too many side effects.

Beta-blockers may be used with other blood pressure-lowering medications, including ACE (Angiotensin-converting Enzyme) inhibitors and calcium channel blockers.

Beta-blockers have been shown to have some health benefits outside of helping the heart. For example, they protect bones by preventing the kidneys from excreting calcium into urine, and block stress hormones that could otherwise cause bone thinning over time.

Types of beta-blockers and how they work

Because of the way they work in the body, beta-blockers are also called beta-adrenergic blocking substances.

Different types of beta-blockers work differently. In general, these medications enhance the heart’s ability to relax. Your heart will beat slower and less forcefully when beta-blockers are working. This can help reduce blood pressure and alleviate irregular heart rhythms.

Some beta-blockers work only on the heart itself, while others affect the heart and blood vessels.

Your doctor may prescribe beta-blockers even if you have few symptoms of heart problems or heart failure. These medications can actually improve the heart’s ability to beat.

Commonly prescribed beta-blockers include:

* acebutolol (Sectral)
* atenolol (Tenormin)
* bisoprolol (Zebeta)
* carteolol (Cartrol)
* esmolol (Brevibloc)
* metoprolol (Lopressor, Toprol XL)
* nadolol (Corgard)
* nebivolol (Bystolic)
* propranolol (Inderal LA)

Beta-blockers are available in different formulas with different routes of administration, including oral, intravenous, and ophthalmic.

Beta-blockers are usually taken once or twice a day with meals, and should generally be taken at the same time every day.

Always take your medication as prescribed. Let your doctor know if you’re having side effects. You should not stop taking your beta-blocker without consulting with your doctor first.

What are beta-blockers used for?

Beta-blockers are used to reduce the speed of your heartbeat and lower your blood pressure. They do so by preventing the hormone adrenaline, as well as other stress hormones, from binding to beta receptors throughout your body.

Beta-blockers are Food and Drug Administration (FDA) approvedTrusted Source for the treatment of heart- and blood pressure-related conditions, including:

* tachycardia
* high blood pressure (hypertension)
* heart attack (myocardial infarction)
* congestive heart failure
* cardiac arrhythmias
* coronary artery disease
* overactive thyroid (hyperthyroidism)
* essential tremor
* aortic dissection
* portal hypertension

Beta-blockers are sometimes prescribed by doctors for off-label use to treat other conditions, including:

* glaucoma
* migraine
* anxiety disorders
* hyperthyroidism
* tremors

Side effects

Side effects of these medications can vary. Many people will experience:

* fatigue
* cold hands
* headache
* digestive problems
* constipation
* diarrhea
* dizziness

Rarely, you may experience:

* shortness of breath
* trouble sleeping
* decreased libido
* depression

If you accidentally take a larger dose than recommended, you may experience:

* difficulty breathing
* changes in vision
* dizziness
* irregular heartbeat
* confusion

If you know that an overdose has occurred, call your doctor or local poison control center.

Some older beta-blockers — such as atenolol and metoprolol — have been reported to cause weight gain. Fluid retention and accompanying weight gain can be signs of have heart failure, or that heart failure is getting worse.

Be sure to let your doctor know if you gain more than 2 to 3 pounds within a day, gain more than 5 pounds within a week, or your symptoms worsen.

You may also notice some changes in the way your heart works during day-to-day life. For example, beta-blockers prevent spikes in heart rate. You may notice that your heart rate doesn’t climb as high as it normally would during exercise.

Speak with your doctor if you’re concerned about your workouts while taking this medication. They may recommend a stress test to determine your target heart rate during cardio.

Stress tests can also help your doctor determine how hard you feel you’re working during a workout. This is known as the rate of perceived exertion.

Interactions and cautions

Other medications can increase or decrease the effect of beta-blockers, so be sure to tell your doctor about all medications, vitamins, and herbal supplements you may be taking.

Beta-blockers can interact with medications such as:

* ACE inhibitors
* allergy medications such as ephedrine, noradrenaline, or adrenaline
* alpha-blockers
* anesthetics
* anti-arrhythmics
* anti-ulcer medications
* antidepressants
* antihypertensive and antianginal drugs
* asthma drugs
* calcium channel blockers
* digitalis glycosides
* HMG-CoA reductase inhibitors
* inotropic agents
* isoproterenol and dobutamine
* neuroleptic drugs
* nonsteroidal anti-inflammatory drugs (NSAIDs)
* oral hypoglycemics
* other blood pressure medications
* psychotropic drugs
* reserpine
* rifampicin (also known as rifampin)
* thyroxine
* warfarin

Beta-blockers should not be used by people with:

* a history of fluid retention without diuretic use
* severe heart failure
* Raynaud’s disease

Historically, beta-blockers have been contraindicated in people with asthma, but this group can safely use cardio-selective beta-blockers, also known as beta-1 selective.

Because beta-blockers may affect blood sugar management, they’re not usually recommended for people with diabetes.

Tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding while taking beta-blockers.

If you’re having surgery, including dental surgery while taking beta-blockers, tell your doctor or dentist.

Can you stop beta-blockers?

Do not stop taking a beta-blocker without consulting with your doctor. Stopping beta-blockers suddenly could cause health complications, including:

* heart palpitations
* raised blood pressure
* chest pain (angina)


Beta-blockers are a commonly prescribed medication used to lower blood pressure, protect against heart attacks, and treat various heart-related conditions. They’re also prescribed off-label for glaucoma, migraine, and anxiety.

Beta-blockers lower your blood pressure by blocking the effects of stress hormones on your heart. Follow the directions on your prescription when taking beta-blockers.

Be sure to tell your doctor about any other drugs, herbs, or supplements you’re taking, as these could affect how beta-blockers work.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1879 2023-08-24 00:14:35

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1883) Advertisement


An advertisement is a piece of information in a newspaper, on television, a picture on a wall, etc. that tries to persuade people to buy something, to interest them in a new job, etc.


Advertisement, also called ad, is a public announcement—generally print, audio, or video—made to promote a commodity, service, or idea through various media, including billboards, direct mail, print magazines and newspapers, radio, television, and the World Wide Web. While advertising is used to a limited extent in every modern society, often by some agency or service of government, it is in countries with economies based on competition that advertising is ubiquitous.

The first ads were generally circulated by public criers, who in ancient times announced the sale of various products to passersby. An advertisement offering a reward for a runaway slave, discovered in the ruins of Thebes and estimated to be 3,000 years old, demonstrated that printed advertisements also existed during this period. The oral advertisement, however, remained the most popular form of advertising until the invention of the printing press about 1450, after which advertisements became more plentiful and sophisticated, the advertiser using persuasion and suggestion to increase patronage. During the 18th and 19th centuries, advertisements were still carried on handbills, posters, and leaflets; however, such media lacked the tremendous circulation of newspapers and magazines, which carried the majority of advertisements during that period.

Newspaper and magazine advertisements popularized jingles and slogans, offered the latest fashions, and guaranteed cures with patent medicines. Advertising media expanded with the development of radio in the 1920s and television in the 1940s, and advertisements became more influential and complex, often based on the results of motivational research. In the second half of the 20th century, television was rivaled only by periodicals as the most popular medium for advertisements, which had so pervaded modern society that there was hardly a public or private area in which they were not seen—from billboards, shop signs, and clothing labels to mail-order catalogs and brochures.

In the early 21st century, with an intensely competitive consumer market, advertisers increasingly used digital technology to call greater attention to products. In 2009, for example, the world’s first video advertisements to be embedded in a print publication appeared in Entertainment Weekly magazine. A thin battery-powered screen implanted in a page could store up to 40 minutes of video via chip technology and would automatically begin to play when the reader opened the page.


Advertising is the practice and techniques employed to bring attention to a product or service. Advertising aims to put a product or service in the spotlight in hopes of drawing it attention from consumers. It is typically used to promote a specific good or service, but there are wide range of uses, the most common being the commercial advertisement.

Commercial advertisements often seek to generate increased consumption of their products or services through "branding", which associates a product name or image with certain qualities in the minds of consumers. On the other hand, ads that intend to elicit an immediate sale are known as direct-response advertising. Non-commercial entities that advertise more than consumer products or services include political parties, interest groups, religious organizations and governmental agencies. Non-profit organizations may use free modes of persuasion, such as a public service announcement. Advertising may also help to reassure employees or shareholders that a company is viable or successful.

In the 19th century, soap businesses were among the first to employ large-scale advertising campaigns. Thomas J. Barratt was hired by Pears to be its brand manager—the first of its kind—and in addition to creating slogans and images he recruited West End stage actress and socialite Lillie Langtry to become the poster-girl for Pears, making her the first celebrity to endorse a commercial product. Modern advertising originated with the techniques introduced with tobacco advertising in the 1920s, most significantly with the campaigns of Edward Bernays, considered the founder of modern, "Madison Avenue" advertising.

Worldwide spending on advertising in 2015 amounted to an estimated US$529.43 billion. Advertising's projected distribution for 2017 was 40.4% on TV, 33.3% on digital, 9% on newspapers, 6.9% on magazines, 5.8% on outdoor and 4.3% on radio. Internationally, the largest ("Big Five") advertising agency groups are Omnicom, WPP, Publicis, Interpublic, and Dentsu.

In Latin, advertere means "to turn towards".


Egyptians used papyrus to make sales messages and wall posters. Commercial messages and political campaign displays have been found in the ruins of Pompeii and ancient Arabia. Lost and found advertising on papyrus was common in ancient Greece and ancient Rome. Wall or rock painting for commercial advertising is another manifestation of an ancient advertising form, which is present to this day in many parts of Asia, Africa, and South America. The tradition of wall painting can be traced back to Indian rock art paintings that date back to 4000 BC.

In ancient China, the earliest advertising known was oral, as recorded in the Classic of Poetry (11th to 7th centuries BC) of bamboo flutes played to sell confectionery. Advertisement usually takes in the form of calligraphic signboards and inked papers. A copper printing plate dated back to the Song dynasty used to print posters in the form of a square sheet of paper with a rabbit logo with "Jinan Liu's Fine Needle Shop" and "We buy high-quality steel rods and make fine-quality needles, to be ready for use at home in no time" written above and below is considered the world's earliest identified printed advertising medium.

In Europe, as the towns and cities of the Middle Ages began to grow, and the general population was unable to read, instead of signs that read "cobbler", "miller", "tailor", or "blacksmith", images associated with their trade would be used such as a boot, a suit, a hat, a clock, a diamond, a horseshoe, a candle or even a bag of flour. Fruits and vegetables were sold in the city square from the backs of carts and wagons and their proprietors used street callers (town criers) to announce their whereabouts. The first compilation of such advertisements was gathered in "Les Crieries de Paris", a thirteenth-century poem by Guillaume de la Villeneuve.

18th-19th century: Newspaper Advertising

In the 18th century advertisements started to appear in weekly newspapers in England. These early print advertisements were used mainly to promote books and newspapers, which became increasingly affordable with advances in the printing press; and medicines, which were increasingly sought after. However, false advertising and so-called "quack" advertisements became a problem, which ushered in the regulation of advertising content.

In the United States, newspapers grew quickly in the first few decades of the 19th century, in part due to advertising. By 1822, the United States had more newspaper readers than any other country. About half of the content of these newspapers consisted of advertising, usually local advertising, with half of the daily newspapers in the 1810s using the word "advertiser" in their name.

In June 1836, French newspaper La Presse was the first to include paid advertising in its pages, allowing it to lower its price, extend its readership and increase its profitability and the formula was soon copied by all titles. Around 1840, Volney B. Palmer established the roots of the modern day advertising agency in Philadelphia. In 1842 Palmer bought large amounts of space in various newspapers at a discounted rate then resold the space at higher rates to advertisers. The actual ad – the copy, layout, and artwork – was still prepared by the company wishing to advertise; in effect, Palmer was a space broker. The situation changed when the first full-service advertising agency of N.W. Ayer & Son was founded in 1869 in Philadelphia. Ayer & Son offered to plan, create, and execute complete advertising campaigns for its customers. By 1900 the advertising agency had become the focal point of creative planning, and advertising was firmly established as a profession.  Around the same time, in France, Charles-Louis Havas extended the services of his news agency, Havas to include advertisement brokerage, making it the first French group to organize. At first, agencies were brokers for advertisement space in newspapers.

Late 19th century: Modern Advertising

Thomas J. Barratt of London has been called "the father of modern advertising". Working for the Pears soap company, Barratt created an effective advertising campaign for the company products, which involved the use of targeted slogans, images and phrases. One of his slogans, "Good morning. Have you used Pears' soap?" was famous in its day and into the 20th century. In 1882, Barratt recruited English actress and socialite Lillie Langtry to become the poster-girl for Pears, making her the first celebrity to endorse a commercial product.

Becoming the company's brand manager in 1865, listed as the first of its kind by the Guinness Book of Records, Barratt introduced many of the crucial ideas that lie behind successful advertising and these were widely circulated in his day. He constantly stressed the importance of a strong and exclusive brand image for Pears and of emphasizing the product's availability through saturation campaigns. He also understood the importance of constantly reevaluating the market for changing tastes and mores, stating in 1907 that "tastes change, fashions change, and the advertiser has to change with them. An idea that was effective a generation ago would fall flat, stale, and unprofitable if presented to the public today. Not that the idea of today is always better than the older idea, but it is different – it hits the present taste."

Enhanced advertising revenues was one effect of the Industrial Revolution in Britain. Thanks to the revolution and the consumers it created, by the mid-19th century biscuits and chocolate became products for the masses, and British biscuit manufacturers were among the first to introduce branding to distinguish grocery products. One the world's first global brands, Huntley & Palmers biscuits were sold in 172 countries in 1900, and their global reach was reflected in their advertisements.

20th century

Advertising revenue as a percent of US GDP shows a rise in audio-visual and digital advertising at the expense of print media.

As a result of massive industrialization, advertising increased dramatically in the United States. In 1919 it was 2.5 percent of gross domestic product (GDP) in the US, and it averaged 2.2 percent of GDP between then and at least 2007, though it may have declined dramatically since the Great Recession.

Industry could not benefit from its increased productivity without a substantial increase in consumer spending. This contributed to the development of mass marketing designed to influence the population's economic behavior on a larger scale. In the 1910s and 1920s, advertisers in the U.S. adopted the doctrine that human instincts could be targeted and harnessed – "sublimated" into the desire to purchase commodities. Edward Bernays, a nephew of Sigmund Freud, became associated with the method and is sometimes called the founder of modern advertising and public relations.
Bernays claimed that:
"[The] general principle, that men are very largely actuated by motives which they conceal from themselves, is as true of mass as of individual psychology. It is evident that the successful propagandist must understand the true motives and not be content to accept the reasons which men give for what they do."

In other words, selling products by appealing to the rational minds of customers (the main method used prior to Bernays) was much less effective than selling products based on the unconscious desires that Bernays felt were the true motivators of human action.

In the 1920s, under Secretary of Commerce Herbert Hoover, the American government promoted advertising. Hoover himself delivered an address to the Associated Advertising Clubs of the World in 1925 called 'Advertising Is a Vital Force in Our National Life." In October 1929, the head of the U.S. Bureau of Foreign and Domestic Commerce, Julius Klein, stated "Advertising is the key to world prosperity." This was part of the "unparalleled" collaboration between business and government in the 1920s, according to a 1933 European economic journal.

The tobacco companies became major advertisers in order to sell packaged cigarettes. The tobacco companies pioneered the new advertising techniques when they hired Bernays to create positive associations with tobacco smoking.

Advertising was also used as a vehicle for cultural assimilation, encouraging workers to exchange their traditional habits and community structure in favor of a shared "modern" lifestyle. An important tool for influencing immigrant workers was the American Association of Foreign Language Newspapers (AAFLN). The AAFLN was primarily an advertising agency but also gained heavily centralized control over much of the immigrant press.

At the turn of the 20th century, advertising was one of the few career choices for women. Since women were responsible for most household purchasing done, advertisers and agencies recognized the value of women's insight during the creative process. In fact, the first American advertising to use a sexual sell was created by a woman – for a soap product. Although tame by today's standards, the advertisement featured a couple with the message "A skin you love to touch".

In the 1920s, psychologists Walter D. Scott and John B. Watson contributed applied psychological theory to the field of advertising. Scott said, "Man has been called the reasoning animal but he could with greater truthfulness be called the creature of suggestion. He is reasonable, but he is to a greater extent suggestible". He demonstrated this through his advertising technique of a direct command to the consumer.

Radio from the 1920s

In the early 1920s, the first radio stations were established by radio equipment manufacturers, followed by non-profit organizations such as schools, clubs and civic groups who also set up their own stations. Retailer and consumer goods manufacturers quickly recognized radio's potential to reach consumers in their home and soon adopted advertising techniques that would allow their messages to stand out; slogans, mascots, and jingles began to appear on radio in the 1920s and early television in the 1930s.

The rise of mass media communications allowed manufacturers of branded goods to bypass retailers by advertising directly to consumers. This was a major paradigm shift which forced manufacturers to focus on the brand and stimulated the need for superior insights into consumer purchasing, consumption and usage behaviour; their needs, wants and aspirations. The earliest radio drama series were sponsored by soap manufacturers and the genre became known as a soap opera. Before long, radio station owners realized they could increase advertising revenue by selling 'air-time' in small time allocations which could be sold to multiple businesses. By the 1930s, these advertising spots, as the packets of time became known, were being sold by the station's geographical sales representatives, ushering in an era of national radio advertising.

By the 1940s, manufacturers began to recognize the way in which consumers were developing personal relationships with their brands in a social/psychological/anthropological sense. Advertisers began to use motivational research and consumer research to gather insights into consumer purchasing. Strong branded campaigns for Chrysler and Exxon/Esso, using insights drawn research methods from psychology and cultural anthropology, led to some of the most enduring campaigns of the 20th century.

Commercial television in the 1950s

In the early 1950s, the DuMont Television Network began the modern practice of selling advertisement time to multiple sponsors. Previously, DuMont had trouble finding sponsors for many of their programs and compensated by selling smaller blocks of advertising time to several businesses. This eventually became the standard for the commercial television industry in the United States. However, it was still a common practice to have single sponsor shows, such as The United States Steel Hour. In some instances the sponsors exercised great control over the content of the show – up to and including having one's advertising agency actually writing the show. The single sponsor model is much less prevalent now, a notable exception being the Hallmark Hall of Fame.

Cable television from the 1980s

The late 1980s and early 1990s saw the introduction of cable television and particularly MTV. Pioneering the concept of the music video, MTV ushered in a new type of advertising: the consumer tunes in for the advertising message, rather than it being a by-product or afterthought. As cable and satellite television became increasingly prevalent, specialty channels emerged, including channels entirely devoted to advertising, such as QVC, Home Shopping Network, and ShopTV Canada.

Internet from the 1990s

With the advent of the ad server, online advertising grew, contributing to the "dot-com" boom of the 1990s. Entire corporations operated solely on advertising revenue, offering everything from coupons to free Internet access. At the turn of the 21st century, some websites, including the search engine Google, changed online advertising by personalizing ads based on web browsing behavior. This has led to other similar efforts and an increase in interactive advertising.

The share of advertising spending relative to GDP has changed little across large changes in media since 1925. In 1925, the main advertising media in America were newspapers, magazines, signs on streetcars, and outdoor posters. Advertising spending as a share of GDP was about 2.9 percent. By 1998, television and radio had become major advertising media; by 2017, the balance between broadcast and online advertising had shifted, with online spending exceeding broadcast. Nonetheless, advertising spending as a share of GDP was slightly lower – about 2.4 percent.

Guerrilla marketing involves unusual approaches such as staged encounters in public places, giveaways of products such as cars that are covered with brand messages, and interactive advertising where the viewer can respond to become part of the advertising message. This type of advertising is unpredictable, which causes consumers to buy the product or idea. This reflects an increasing trend of interactive and "embedded" ads, such as via product placement, having consumers vote through text messages, and various campaigns utilizing social network services such as Facebook or Twitter.

The advertising business model has also been adapted in recent years. In media for equity, advertising is not sold, but provided to start-up companies in return for equity. If the company grows and is sold, the media companies receive cash for their shares.

Domain name registrants (usually those who register and renew domains as an investment) sometimes "park" their domains and allow advertising companies to place ads on their sites in return for per-click payments. These ads are typically driven by pay per click search engines like Google or Yahoo, but ads can sometimes be placed directly on targeted domain names through a domain lease or by making contact with the registrant of a domain name that describes a product. Domain name registrants are generally easy to identify through WHOIS records that are publicly available at registrar websites.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1880 2023-08-25 01:03:42

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1884) Hunger


i) a compelling need or desire for food.
ii) the painful sensation or state of weakness caused by the need of food.
iii) a shortage of food; famine.


World Food Programme (WFP) is an organization established in 1961 by the United Nations (UN) to help alleviate world hunger. Its headquarters are in Rome, Italy. In 2020 the World Food Programme (WFP) was awarded the Nobel Prize for Peace “for its efforts to combat hunger, for its contribution to bettering conditions for peace in conflict-affected areas and for acting as a driving force in efforts to prevent the use of hunger as a weapon of war and conflict.”

The WFP’s programs are aimed at helping the nearly 11 percent of the world’s population that does not have enough to eat. The organization works to achieve the second of the UN’s 17 Sustainable Development Goals, Zero Hunger, which pledges to end hunger, achieve food security and improve nutrition, and promote sustainable agriculture worldwide. The WFP aids victims of both natural and human-made disasters by collecting and transporting food to crisis areas. It helps people affected by wars and other conflicts, epidemics and pandemics, crop failures, and disasters such as floods, droughts, earthquakes, and storms. In addition to distributing food aid in emergencies, the WFP provides food assistance to meet longer-term needs. The WFP focuses particularly on assisting vulnerable groups such as children, pregnant and nursing women, and the elderly. To stimulate their economies, the WFP purchases more goods and services from developing countries than any other UN agency.

The WFP’s Executive Board consists of 36 states, half elected by the UN’s Economic and Social Council (ECOSOC) and half elected by the council of the Food and Agriculture Organization (FAO).


In politics, humanitarian aid, and the social sciences, hunger is defined as a condition in which a person does not have the physical or financial capability to eat sufficient food to meet basic nutritional needs for a sustained period. In the field of hunger relief, the term hunger is used in a sense that goes beyond the common desire for food that all humans experience, also known as an appetite. The most extreme form of hunger, when malnutrition is widespread, and when people have started dying of starvation through lack of access to sufficient, nutritious food, leads to a declaration of famine.

Throughout history, portions of the world's population have often suffered sustained periods of hunger. In many cases, hunger resulted from food supply disruptions caused by war, plagues, or adverse weather. In the decades following World War II, technological progress and enhanced political cooperation suggested it might be possible to substantially reduce the number of people suffering from hunger. While progress was uneven, by 2014, the threat of extreme hunger had receded for a large portion of the world's population. According to the FAO's 2021 The State of Food Security and Nutrition in the World (SOFI) report, the number of people suffering from chronic hunger began to rise gradually between 2014 and 2019. In 2020, due to the COVID-19 pandemic, there was a massive increase, resulting in nearly 770 million people suffering from malnutrition.

While most of the world's people continue to live in Asia, much of the increase in hunger since 2015 occurred in Africa and South America. The FAO's 2017 report discussed three principal reasons for the recent increase in hunger: climate, conflict, and economic slowdowns. The 2018 edition focused on extreme weather as a primary driver of the increase in hunger, finding rising rates to be especially severe in countries where agricultural systems were most sensitive to extreme weather variations. The 2019 SOFI report found a strong correlation between increases in hunger and countries that had suffered an economic slowdown. The 2020 edition instead looked at the prospects of achieving the hunger related Sustainable Development Goal (SDG). It warned that if nothing was done to counter the adverse trends of the past six years, the number of people suffering from chronic hunger could rise by over 150 million by 2030. The 2021 report reported a sharp jump in hunger caused by the COVID-19 pandemic.

Many thousands of organizations are engaged in the field of hunger relief, operating at local, national, regional, or international levels. Some of these organizations are dedicated to hunger relief, while others may work in several different fields. The organizations range from multilateral institutions to national governments, to small local initiatives such as independent soup kitchens. Many participate in umbrella networks that connect thousands of different hunger relief organizations. At the global level, much of the world's hunger relief efforts are coordinated by the UN and geared towards achieving SDG 2 of Zero Hunger by 2030.

Definition and related terms

There is one globally recognized approach for defining and measuring hunger generally used by those studying or working to relieve hunger as a social problem. This is the United Nation's FAO measurement, which is typically referred to as chronic undernourishment (or in older publications, as 'food deprivation,' 'chronic hunger,' or just plain 'hunger.') For the FAO:

* Hunger or chronic undernourishment exists when "caloric intake is below the minimum dietary energy requirement (MDER). The MDER is the amount of energy needed to perform light activity and to maintain a minimum acceptable weight for attained height." The FAO use different MDER thresholds for different countries, due to variations in climate and cultural factors. Typically a yearly "balance sheet" approach is used, with the minimum dietary energy requirement tallied against the estimated total calories consumed over the year. The FAO definitions differentiate hunger from malnutrition and food insecurity.
* Malnutrition results from "deficiencies, excesses or imbalances in the consumption of macro- and/or micro-nutrients." In the FAO definition, all hungry people suffer from malnutrition, but people who are malnourished may not be hungry. They may get sufficient raw calories to avoid hunger but lack essential micronutrients, or they may even consume an excess of raw calories and hence suffer from obesity.
* Food insecurity occurs when people are at risk, or worried about, not being able to meet their preferences for food, including in terms of raw calories and nutritional value. In the FAO definition, all hungry people are food insecure, but not all food-insecure people are hungry (though there is a very strong overlap between hunger and severe food insecurity.). The FAO have reported that food insecurity quite often results in simultaneous stunted growth for children, and obesity for adults. For hunger relief actors operating at the global or regional level, an increasingly commonly used metric for food insecurity is the IPC scale.
* Acute hunger is typically used to denote famine like hunger, though the phrase lacks a widely accepted formal definition. In the context of hunger relief, people experiencing 'acute hunger' may also suffer from 'chronic hunger'. The word is used mainly to denote severity, not long-term duration.

Not all of the organizations in the hunger relief field use the FAO definition of hunger. Some use a broader definition that overlaps more fully with malnutrition. The alternative definitions do however tend to go beyond the commonly understood meaning of hunger as a painful or uncomfortable motivational condition; the desire for food is something that all humans frequently experience, even the most affluent, and is not in itself a social problem.

Very low food supply can be described as "food insecure with hunger." A change in description was made in 2006 at the recommendation of the Committee on National Statistics (National Research Council, 2006) in order to distinguish the physiological state of hunger from indicators of food availability. Food insecure is when food intake of one or more household members was reduced and their eating patterns were disrupted at times during the year because the household lacked money and other resources for food. Food security statistics is measured by using survey data, based on household responses to items about whether the household was able to obtain enough food to meet their needs.

(The Integrated Food Security Phase Classification (IPC), also known as IPC scale, is a tool for improving food security analysis and decision-making. It is a standardised scale that integrates food security, nutrition and livelihood information into a statement about the nature and severity of a crisis and implications for strategic response.

The IPC was originally developed in 2004 for use in Somalia by the United Nations Food and Agriculture Organization's Food Security Analysis Unit (FSAU). Several national governments and international agencies, including CARE International, European Commission Joint Research Centre (EC JRC), Food and Agricultural Organization of the United Nations (FAO), USAID/FEWS NET, Oxfam GB, Save the Children UK/US, and United Nations World Food Programme (WFP), have been working together to adapt it to other food security contexts.)

Additional Information

Much has changed since 1974, when FAO first began reporting on the extent of hunger in the world. The world population is growing steadily and is increasingly urbanized. Technology is evolving incessantly and the economy is more and more globalized. At the same time, there are worrying global trends in malnutrition, including a rapid rise in overweight and obesity, even as forms of undernutrition persist. The way food is produced, distributed and consumed worldwide has also changed dramatically. This vastly different world calls for new ways of thinking about hunger and food insecurity.

As part of its mandate, FAO strives to eradicate hunger, food insecurity and all forms of malnutrition. Supporting the livelihoods of small-scale food producers, improving the resilience of food production systems and encouraging the sustainable use of natural resources are all key to fulfilling this mandate and achieving Sustainable Development Goal 2 (SDG2), a world without hunger, food insecurity and malnutrition.

What is hunger?

Hunger is an uncomfortable or painful physical sensation caused by insufficient consumption of dietary energy. It becomes chronic when the person does not consume a sufficient amount of calories (dietary energy) on a regular basis to lead a normal, active and healthy life. For decades, FAO has used the Prevalence of Undernourishment indicator to estimate the extent of hunger in the world, thus “hunger” may also be referred to as undernourishment.

What is food insecurity?

A person is food insecure when they lack regular access to enough safe and nutritious food for normal growth and development and an active and healthy life. This may be due to unavailability of food and/or lack of resources to obtain food. Food insecurity can be experienced at different levels of severity.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1881 2023-08-26 00:44:25

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1885) Electrician


A electrician is a person whose job is to make and repair electrical systems and equipment.


The Electrician will install and maintain the electrical wiring, fixtures, and systems in buildings.


* Installs and repairs electrical wiring, systems, and fixtures in buildings.
* Installs conduits and pipes to house electrical wires and cables.
* Ensures piping complies with electrical codes.
* Installs circuit breakers and other electrical hardware and connects wiring to them.
* Connects electrical systems to powerlines to provide electricity to the building.
* Tests electrical systems to ensure proper installation and operation.
* Inspects electrical systems to determine whether repairs are needed.
* Replaces conduit and wiring as needed.
* Replaces circuit breakers as needed.
* Performs other related duties as assigned.

Required Skills/Abilities:

* Ability to read blueprints.
* Extensive knowledge of electrical systems and wiring.
* Ability to use hand tools and power tools.
* Proficient in the use of test meters and other diagnostic equipment.
* Excellent analytical and problem-solving skills.

Education and Experience:

* High school diploma or equivalent required.
* Completion of a formal apprenticeship and valid electricians license required.

Physical Requirements:

* Must be able to see color to discern color-coded wiring.
* Prolonged periods standing, kneeling, bending, and climbing ladders or scaffolding.
* Must be physically capable of pulling wires and cables through conduits.
* Must be able to lift up to 50 pounds at a time.


An electrician is a tradesperson specializing in electrical wiring of buildings, transmission lines, stationary machines, and related equipment. Electricians may be employed in the installation of new electrical components or the maintenance and repair of existing electrical infrastructure. Electricians may also specialize in wiring ships, airplanes, and other mobile platforms, as well as data and cable lines.


Electricians were originally people who demonstrated or studied the principles of electricity, often electrostatic generators of one form or another.

In the United States, electricians are divided into two primary categories: lineperson, who work on electric utility company distribution systems at higher voltages, and wiremen, who work with the lower voltages utilized inside buildings. Wiremen are generally trained in one of five primary specialties: commercial, residential, light industrial, industrial, and low-voltage wiring, more commonly known as Voice-Data-Video, or VDV. Other sub-specialties such as control wiring and fire-alarm may be performed by specialists trained in the devices being installed, or by inside wiremen.

Electricians are trained to one of three levels: Apprentice, Journeyperson, and Master Electrician. In the US and Canada, apprentices work and receive a reduced compensation while learning their trade. They generally take several hundred hours of classroom instruction and are contracted to follow apprenticeship standards for a period of between three and six years, during which time they are paid as a percentage of the Journeyperson's pay. Journeymen are electricians who have completed their Apprenticeship and who have been found by the local, State, or National licensing body to be competent in the electrical trade. Master Electricians have performed well in the trade for a period of time, often seven to ten years, and have passed an exam to demonstrate superior knowledge of the National Electrical Code, or NEC.

Service electricians are tasked to respond to requests for isolated repairs and upgrades. They have skills troubleshooting wiring problems, installing wiring in existing buildings, and making repairs. Construction electricians primarily focus on larger projects, such as installing all new electrical system for an entire building, or upgrading an entire floor of an office building as part of a remodeling process. Other specialty areas are marine electricians, research electricians and hospital electricians. "Electrician" is also used as the name of a role in stagecraft, where electricians are tasked primarily with hanging, focusing, and operating stage lighting. In this context, the Master Electrician is the show's chief electrician. Although theater electricians routinely perform electrical work on stage lighting instruments and equipment, they are not part of the electrical trade and have a different set of skills and qualifications from the electricians that work on building wiring.

In the film industry and on a television crew the head electrician is referred to as a Gaffer.

Electrical contractors are businesses that employ electricians to design, install, and maintain electrical systems. Contractors are responsible for generating bids for new jobs, hiring tradespeople for the job, providing material to electricians in a timely manner, and communicating with architects, electrical and building engineers, and the customer to plan and complete the finished product.

Many jurisdictions have regulatory restrictions concerning electrical work for safety reasons due to the many hazards of working with electricity. Such requirements may be testing, registration or licensing. Licensing requirements vary between jurisdictions.


An electrician's license entitles the holder to carry out all types of electrical installation work in Australia without supervision. However, to contract, or offer to contract, to carry out electrical installation work, a licensed electrician must also be registered as an electrical contractor. Under Australian law, electrical work that involves fixed wiring is strictly regulated and must almost always be performed by a licensed electrician or electrical contractor. A local electrician can handle a range of work including air conditioning, light fittings and installation, safety switches, smoke alarm installation, inspection and certification and testing and tagging of electrical appliances.

To provide data, structured cabling systems, home automation & theatre, LAN, WAN and VPN data solutions or phone points, an installer must be licensed as a Telecommunications Cable Provider under a scheme controlled by Australian Communications and Media Authority.

Electrical licensing in Australia is regulated by the individual states. In Western Australia, the Department of Commerce tracks licensee's and allows the public to search for individually named/licensed Electricians.

Currently in Victoria the apprenticeship lasts for four years, during three of those years the apprentice attends trade school in either a block release of one week each month or one day each week. At the end of the apprenticeship the apprentice is required to pass three examinations, one of which is theory based with the other two practically based. Upon successful completion of these exams, providing all other components of the apprenticeship are satisfactory, the apprentice is granted an A Class licence on application to Energy Safe Victoria (ESV).

An A Class electrician may perform work unsupervised but is unable to work for profit or gain without having the further qualifications necessary to become a Registered Electrical Contractor (REC) or being in the employment of a person holding REC status. However, some exemptions do exist.

In most cases a certificate of electrical safety must be submitted to the relevant body after any electrical works are performed.

Safety equipment used and worn by electricians in Australia (including insulated rubber gloves and mats) needs to be tested regularly to ensure it is still protecting the worker. Because of the high risk involved in this trade, this testing needs to be performed regularly and regulations vary according to state. Industry best practice is the Queensland Electrical Safety Act 2002, and requires six-monthly testing.


Training of electricians follows an apprenticeship model, taking four or five years to progress to fully qualified journeyperson level. Typical apprenticeship programs consists of 80-90% hands-on work under the supervision of journeymen and 10-20% classroom training. Training and licensing of electricians is regulated by each province, however professional licenses are valid throughout Canada under Agreement on Internal Trade. An endorsement under the Red Seal Program provides additional competency assurance to industry standards. In order for individuals to become a licensed electricians, they need to have 9000 hours of practical, on the job training. They also need to attend school for 4 terms and pass a provincial exam. This training enables them to become journeyperson electricians. Furthermore, in British Columbia, an individual can go a step beyond that and become a "FSR", or field safety representative. This credential gives the ability to become a licensed electrical contractor and to pull permits. Notwithstanding this, some Canadian provinces only grant "permit pulling privileges" to current Master Electricians, that is, a journeyperson who has been engaged in the industry for three years and has passed the Master's examination (i.e. Alberta). The various levels of field safety representatives are A, B and C. The only difference between each class is that they are able to do increasingly higher voltage and current work.

United Kingdom

The two qualification awarding organisations are City and Guilds and EAL. Electrical competence is required at Level 3 to practice as a 'qualified electrician' in the UK. Once qualified and demonstrating the required level of competence an Electrician can apply to register for a Joint Industry Board Electrotechnical Certification Scheme card in order to work on building sites or other controlled areas.

Although partly covered during Level 3 training, more in depth knowledge and qualifications can be obtained covering subjects such as Design and Verification or Testing and Inspection among others. These additional qualifications can be listed on the reverse of the JIB card. Beyond this level is additional training and qualifications such as EV charger installations or training and working in specialist areas such as street furniture or within industry.

The Electricity at Work Regulations are a statutory document that covers the use and proper maintenance of electrical equipment and installations within businesses and other organisations such as charities. Parts of the Building Regulations cover the legal requirements of the installation of electrical technical equipment with Part P outlining most of the regulations covering dwellings.

Information regarding design, selection, installation and testing of electrical structures is provided in the non-statutory publication 'Requirements for Electrical Installations, IET Wiring Regulations, Eighteenth Edition, BS 7671:2018' otherwise known as the Wiring Regulations or 'Regs'. Usual amendments are published on an ad hoc bases when minor changes occur. The first major update of the 18th Edition were published during February 2020 mainly covering the section covering Electric vehicles charger installations although an addendum was published during December 2019 correcting some minor mistakes and adding some small changes. The IET also publish a series of 'Guidance Notes' in book form that provide further in-depth knowledge.

With the exception of the work covered by Part P of the Building Regulations, such as installing consumer units, new circuits or work in bathrooms, there are no laws that prevent anyone from carrying out some basic electrical work in the UK.

In British English, an electrician is colloquially known as a "spark".

United States

The United States does not offer nationwide licensing and electrical licenses are issued by individual states. There are variations in licensing requirements, however, all states recognize three basic skill categories: level electricians. Journeyperson electricians can work unsupervised provided that they work according to a master's direction. Generally, states do not offer journeyperson permits, and journeyperson electricians and other apprentices can only work under permits issued to a master electrician. Apprentices may not work without direct supervision.

Before electricians can work unsupervised, they are usually required to serve an apprenticeship lasting three to five years under the general supervision of a master electrician and usually the direct supervision of a journeyperson electrician. Schooling in electrical theory and electrical building codes is required to complete the apprenticeship program. Many apprenticeship programs provide a salary to the apprentice during training. A journeyperson electrician is a classification of licensing granted to those who have met the experience requirements for on the job training (usually 4,000 to 6,000 hours) and classroom hours (about 144 hours). Requirements include completion of two to six years of apprenticeship training and passing a licensing exam.


An electrician's license is valid for work in the state where the license was issued. In addition, many states recognize licenses from other states, sometimes called interstate reciprocity participation, although there can be conditions imposed. For example, California reciprocates with Arizona, Nevada, and Utah on the condition that licenses are in good standing and have been held at the other state for five years. Nevada reciprocates with Arizona, California, and Utah. Maine reciprocates with New Hampshire and Vermont at the master level, and the state reciprocates with New Hampshire, North Dakota, Idaho, Oregon, Vermont, and Wyoming at the journeyperson level. Colorado maintains a journeyperson alliance with Alaska, Arkansas, the Dakotas, Idaho, Iowa, Minnesota, Montana, Nebraska, New Hampshire, New Mexico, Oklahoma, Utah, and Wyoming.


Electricians use a range of hand and power tools and instruments.

Some of the more common tools are:

* Conduit Bender: Bender used to bend various types of Electrical Conduit. These come in many variations including hand, electrical, and hydraulic powered.
* Non-Contact Voltage Testers
* Lineperson's Pliers: Heavy-duty pliers for general use in cutting, bending, crimping and pulling wire.
* Diagonal Pliers (also known as side cutters or Dikes): Pliers consisting of cutting blades for use on smaller gauge wires, but sometimes also used as a gripping tool for removal of nails and staples.
* Needle-Nose Pliers: Pliers with a long, tapered gripping nose of various size, with or without cutters, generally smaller and for finer work (including very small tools used in electronics wiring).
* Wire Strippers: Plier-like tool available in many sizes and designs featuring special blades to cut and strip wire insulation while leaving the conductor wire intact and without nicks. Some wire strippers include cable strippers among their multiple functions, for removing the outer cable jacket.
* Cable Cutters: Highly leveraged pliers for cutting larger cable.
* Armored Cable Cutters: Commonly referred to by the trademark 'Roto-Split', is a tool used to cut the metal sleeve on MC (Metal Clad) cable.
* Multimeter: An instrument for electrical measurement with multiple functions. It is available as analog or digital display. Common features include: voltage, resistance, and current. Some models offer additional functions.
* Unibit or Step-Bit: A metal-cutting drill bit with stepped-diameter cutting edges to enable convenient drilling holes in preset increments in stamped/rolled metal up to about 1.6mm (1/16 inch) thick. Commonly used to create custom knock-outs in a breaker panel or junction box.
* Cord, Rope or Fish Tape. Used to manipulate cables and wires through cavities. The fishing tool is pushed, dropped, or shot into the installed raceway, stud-bay or joist-bay of a finished wall or in a floor or ceiling. Then the wire or cable is attached and pulled back.
* Crimping Tools: Used to apply terminals or splices. These may be hand or hydraulic powered. Some hand tools have ratchets to insure proper pressure. Hydraulic units achieve cold welding, even for aluminum cable.
* Insulation Resistance Tester: Commonly referred to as a Megger, these testers apply several hundred to several thousand volts to cables and equipment to determine the insulation resistance value.
* Knockout Punch: For punching holes into boxes, panels, switchgear, etc. for inserting cable & pipe connectors.
* GFI/GFCI Testers: Used to test the functionality of Ground-Fault Interrupting receptacles.
* Voltmeter: An electrician's tool used to measure electrical potential difference between two points in an electric circuit.

Other general-use tools include screwdrivers, hammers, reciprocating saws, drywall saws, flashlights, chisels, tongue and groove pliers (Commonly referred to as 'Channellock®' pliers, a famous manufacturer of this tool) and drills.


In addition to the workplace hazards generally faced by industrial workers, electricians are also particularly exposed to injury by electricity. An electrician may experience electric shock due to direct contact with energized circuit conductors or due to stray voltage caused by faults in a system. An electric arc exposes eyes and skin to hazardous amounts of heat and light. Faulty switchgear may cause an arc flash incident with a resultant blast. Electricians are trained to work safely and take many measures to minimize the danger of injury. Lockout and tagout procedures are used to make sure that circuits are proven to be de-energized before work is done. Limits of approach to energized equipment protect against arc flash exposure; specially designed flash-resistant clothing provides additional protection; grounding (earthing) clamps and chains are used on line conductors to provide a visible assurance that a conductor is de-energized. Personal protective equipment provides electrical insulation as well as protection from mechanical impact; gloves have insulating rubber liners, and work boots and hard hats are specially rated to provide protection from shock. If a system cannot be de-energized, insulated tools are used; even high-voltage transmission lines can be repaired while energized, when necessary.

Electrical workers, which includes electricians, accounted for 34% of total electrocutions of construction trades workers in the United States between 1992 and 2003.

Working conditions

Working conditions for electricians vary by specialization. Generally an electrician's work is physically demanding such as climbing ladders and lifting tools and supplies. Occasionally an electrician must work in a cramped space or on scaffolding, and may frequently be bending, squatting or kneeling, to make connections in awkward locations. Construction electricians may spend much of their days in outdoor or semi-outdoor loud and dirty work sites. Industrial electricians may be exposed to the heat, dust, and noise of an industrial plant. Power systems electricians may be called to work in all kinds of adverse weather to make emergency repairs.

Trade organizations

Some electricians are union members and work under their union's policies.


Electricians can choose to be represented by the Electrical Trade Union (ETU). Electrical Contractors can be represented by the National Electrical & Communications Association or Master Electricians Australia.

North America

Some electricians are union members. Some examples of electricians' unions include the International Brotherhood of Electrical Workers, Canadian Union of Public Employees, and the International Association of Machinists and Aerospace Workers.

The International Brotherhood of Electrical Workers provides its own apprenticeships through its National Joint Apprenticeship and Training Committee and the National Electrical Contractors Association. Many merit shop training and apprenticeship programs also exist, including those offered by such as trade associations as Associated Builders and Contractors and Independent Electrical Contractors. These organizations provide comprehensive training, in accordance with U.S. Department of Labor regulations.

United Kingdom/Ireland

In the United Kingdom, electricians are represented by several unions including Unite the Union

In the Republic of Ireland there are two self-regulation/self certification bodies RECI Register of Electrical Contractors of Ireland and ECSSA.

Auto electrician

An auto electrician is a tradesperson specializing in electrical wiring of motor vehicles. Auto electricians may be employed in the installation of new electrical components or the maintenance and repair of existing electrical components. Auto electricians specialize in cars and commercial vehicles. The auto electrical trade is generally more difficult than the electrical trade due to the confined spaces, engineering complexity of modern automotive electrical systems, and working conditions (often roadside breakdowns or on construction sites, mines, quarries to repair machinery etc.) Also the presence of high-current DC electricity makes injury from burns and arc-flash injury possible.

Additional Information

Electricians work with electrical power. They install, test, and maintain wiring, lighting systems, and fixtures in homes and businesses.

Electricians work indoors and outdoors. They work in new construction and in existing buildings. Electricians should have a basic understanding of mathematics, including algebra, and good problem-solving skills. Experienced electricians can work with architects and help design electrical systems for new buildings. Electricians also work with alternative energy sources that turn wind or sunlight into electricity.

It takes commitment to gain the proper training to become an electrician. Electricians need to have a license to be able to work in most states. Most electricians earn their licenses by participating in an apprenticeship program. An apprenticeship is when a student is taught a trade with hands-on experience by a master. This program lasts about 4–5 years. In addition to working on projects during this time the apprentice must also take hundreds of hours of technical courses.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1882 2023-08-27 00:19:06

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1886) Health insurance


Health insurance or medical insurance (also known as medical aid in South Africa) is a type of insurance that covers the whole or a part of the risk of a person incurring medical expenses. As with other types of insurance, risk is shared among many individuals. By estimating the overall risk of health risk and health system expenses over the risk pool, an insurer can develop a routine finance structure, such as a monthly premium or payroll tax, to provide the money to pay for the health care benefits specified in the insurance agreement. The benefit is administered by a central organization, such as a government agency, private business, or not-for-profit entity.

According to the Health Insurance Association of America, health insurance is defined as "coverage that provides for the payments of benefits as a result of sickness or injury. It includes insurance for losses from accident, medical expense, disability, or accidental death and dismemberment".


Health insurance is a contract between a company and a consumer. The company agrees to pay all or some of the insured person's healthcare costs in return for payment of a monthly premium.

The contract is usually a one-year agreement, during which the insurer will be responsible for paying specific expenses related to illness, injury, pregnancy, or preventative care.

Health insurance agreements in the U.S. generally come with exceptions to coverage including:

* A deductible that requires the consumer to pay certain healthcare costs "out-of-pocket" up to a maximum amount before the company coverage begins
* One or more co-payments that require the consumer to pay a set share of the cost for specific services or procedures


* Health insurance pays most medical and surgical expenses and preventative care costs incurred by the insured person in return for a monthly premium payment.

* Generally, the higher the monthly premium is the lower the out-of-pocket costs are to the insured.

* Virtually all insurance plans have deductibles and co-pays but these out-of-pocket expenses are now capped by federal law.

* Since 2010, the Affordable Care Act has prohibited insurance companies from denying coverage to patients with preexisting conditions and has allowed children to remain on their parents' insurance plan until they reach the age of 26.

* Medicare, Medicaid, and the Children's Health Insurance Program (CHIP) are federal health insurance plans that extend coverage to older, disabled, and low-income people.

How Health Insurance Works

In the United States, health insurance is tricky to navigate. It is a business with a number of regional and national competitors whose coverage, pricing, and availability vary from state to state and even by county.

About half of the population has health insurance coverage as an employment benefit, with premiums partially covered by the employer.

The cost to the employer is tax-deductible to the payer, and the benefits to the employee are tax-free, with certain exceptions for S corporation employees.

Self-employed people, freelancers, and gig workers can buy insurance directly on their own. The Affordable Care Act of 2010, commonly called Obamacare, mandated the creation of a national database, called, which allows individuals to search for standard plans from private insurers that are available where they live. The costs of the coverage are subsidized for taxpayers whose incomes are between 100% and 400% of the federal poverty threshold.

Some, but not all, states created their own versions of that are tailored to their residents.

People over the age of 65 and those with disabilities, End-Stage Renal Disease, or ALS qualify to receive federally-subsidized care through Medicare, while families whose incomes are near the poverty level are eligible for subsidized Medicaid coverage.

Types of Health Insurance

Health insurance can be tricky to navigate in the U.S.

So-called managed care insurance plans require policyholders to get their care from a network of designated healthcare providers. If patients seek care outside the network, they must pay a higher percentage of the cost. The insurer may even refuse payment outright for services obtained out of network.

Many managed care plans—for example, health maintenance organizations (HMOs) and point-of-service plans (POS)—require patients to choose a primary care physician who oversees the patient's care, makes recommendations about treatment, and provides referrals for medical specialists.

Preferred-provider organizations (PPOs), by contrast, don't require referrals but do set lower rates for using in-network practitioners and services.

Insurance companies may deny coverage for certain services that were obtained without preauthorization. They may refuse payment for name-brand drugs if a generic version or comparable medication is available at a lower cost.

All these rules should be stated in the material provided by the insurance company. It's worth checking with the company directly before incurring a major expense.

What Are Copays, Deductibles, and Coinsurance?

Most health insurance plans require their customers to pick up some of the costs of their coverage in various ways:

* The deductible is the amount that the customer must pay out of pocket every year before the insurer begins to meet the costs. This is now capped by federal law.
* Copays are set fees that subscribers must pay for specific services such as doctor visits and prescription drugs even after the deductible is met.
* Coinsurance is the percentage of healthcare costs that the insured must pay even after they've met the deductible (but only until they reach the out-of-pocket maximum for the year).
* Insurance plans with higher out-of-pocket costs generally have smaller monthly premiums. When shopping for plans, weigh the benefit of lower monthly payments against the potential risk of large out-of-pocket expenses in the case of a major illness or accident.


If you're self-employed, you may be able to deduct up to 100% of health insurance premiums you pay out of pocket.

High-Deductible Health Plans (HDHP)

One increasingly popular type of health insurance is the high-deductible health plan (HDHP). These plans have higher deductibles and lower monthly premiums. Their users are the only ones eligible to open a Health Savings Account (HSA) that has substantial federal tax benefits.

For 2023, the IRS defines a high-deductible health plan as one that has deductibles of at least $1,500 for an individual or $3,000 for a family. Total out-of-pocket maximums are $7,500 for an individual and $15,000 for a family.

For 2024, a high-deductible health plan is one that has deductibles of at least $1,600 for an individual or $3,100 for a family. Total out-of-pocket maximums are $8,050 for an individual and $16,100 for a family.

High-deductible health plans offer a unique advantage in that if you have one, you're permitted to open—and contribute pretax income to—a health savings account, which can be used to pay for qualified medical expenses. These plans offer a triple tax benefit in that:

* Contributions are tax-deductible
* Contributions grow on a tax-deferred basis
* Qualified withdrawals for healthcare expenses are tax-free


You can withdraw money from an HSA after age 65 for any reason with no tax penalty, but you will pay income tax on the withdrawal if the money is not used for qualified medical expenses.

Federal Health Insurance Plans

Not all health insurance in the US is provided by private companies. Medicare, Medicaid, and the Children's Health Insurance Program (CHIP) are federal health insurance plans that extend coverage to older, disabled, and low-income people.

The Affordable Care Act (ACA)

In 2010, President Barack Obama signed the Affordable Care Act (ACA) into law. In participating states, the act expanded Medicaid, a government program that provides medical care for individuals with low incomes.

The Affordable Care Act has prohibited insurance companies from denying coverage to patients with preexisting conditions and has allowed children to remain on their parents' insurance plan until they reach the age of 26.

In addition to these changes, the ACA established the federal Health Insurance Marketplace. It also prohibits insurance companies from denying coverage to patients with preexisting conditions and allows children to remain on their parents' insurance plan until they reach age 26.

The Marketplace helps individuals and businesses shop for quality insurance plans at affordable rates. Insurance available through the ACA Marketplace is required to cover 10 essential health benefits.

Through the website, shoppers can find the Marketplace in their state, if it has one.

Under the ACA, tax-payers were required to carry medical insurance that meets federally designated minimum standards or face a tax penalty, but the Tax Cuts and Job Act removed that penalty after December 31, 2018.

A Supreme Court ruling in 2012 struck down an ACA provision that required states to expand Medicaid eligibility as a condition for receiving federal Medicaid funding, and a number of states chose to refuse to expand their Medicaid programs.

As of 2023, an estimated 40 million people have health coverage through the Affordable Care Act.

Medicare and CHIP

Two public health insurance plans, Medicare and the Children's Health Insurance Program (CHIP), provide subsidized coverage for disabled individuals and children. Medicare, which is available to people age 65 or older, also serves people with certain disabilities, End-Stage Renal Disease, and ALS. The CHIP plan provides health coverage for low-income children under the age of 19.

Medicaid can help older seniors to pay for long-term care in a nursing home, but Medicare does not. This is why Medicare recipients often pay for supplemental coverage through a private insurer.

What Is Health Insurance and Why Do You Need It?

Health insurance is an agreement in which an insurance company agrees to pay for some or all of your medical expenses in exchange for a monthly premium payment.

If you're young, healthy, and lucky, the monthly premium may exceed the costs of your insurance.

If you (or someone in your family) have a recurring condition that needs treatment or develop one, are injured in an accident, or develop a disease, you may well incur medical bills that you cannot possibly pay.

Who Needs Health Insurance?

The simple answer is everyone. Health insurance offsets the costs of minor medical issues and major ones, including surgeries and treatment for life-threatening ailments and debilitating conditions.

How Do You Get Health Insurance?

If your employer offers health insurance as part of an employee benefits package, you will be covered, although you will probably have to pay a portion of the costs.

If you are self-employed, you can purchase health insurance through a federal or state Health Insurance Marketplace.

People over the age of 65 qualify for federal Medicare insurance, although many of them supplement its coverage.

Low-income individuals and families qualify for subsidized coverage through the federal Medicaid or Medicare programs.

How Much Does Health Insurance Cost?

The cost of health insurance varies widely based on the scope of coverage, the type of plan you have, the deductible, and your age when you sign up. Copays and coinsurance also add to your expenses.

You can get a good sense of the costs of plans by looking at the four levels of coverage offered by the federal Health Insurance Marketplace. It categorizes plans as bronze, silver, gold, or platinum, with each category priced according to the level of coverage provided and their corresponding costs to the user.

The Bottom Line

Unlike many countries, the U.S. does not have a universal government health care system. Instead, it has a complicated system of subsidies and tax incentives that make health care affordable for most people most of the time.

If you are employed, you probably have health insurance that is subsidized by your employer. If you are self-employed, you can get insurance directly from a private insurer. If your income is low, you can get a subsidy for the costs. If you are elderly or disabled, you can get coverage through the federal Medicare or Medicaid programs.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1883 2023-08-28 00:50:04

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1887) Veterinarian


Veterinarian is a person qualified to treat diseased or injured animals; a veterinary surgeon.


Veterinary medicine, also called veterinary science, is a medical specialty concerned with the prevention, control, diagnosis, and treatment of diseases affecting the health of domestic and wild animals and with the prevention of transmission of animal diseases to people. Veterinarians ensure a safe food supply for people by monitoring and maintaining the health of food-producing animals.

Persons serving as doctors to animals have existed since the earliest recorded times, and veterinary practice was already established as a specialty as early as 2000 BCE in Babylonia and Egypt. The ancient Greeks had a class of physicians who were called “horse-doctors,” and the Latin term for the specialty, veterinarius (“pertaining to beast of burden”), came to denote the field in modern times. Today veterinarians serve worldwide in private and corporate clinical practice, academic programs, private industry, government service, public health, and military services. They often are supported in their work by other veterinary medicine professionals, such as veterinary nurses and veterinary technicians.

Veterinary medicine has made many important contributions to animal and human health. Included are dramatic reductions in animal sources of human exposure to tuberculosis and brucellosis. Safe and effective vaccines have been developed for prevention of many companion (pet) animal diseases—e.g., canine distemper and feline distemper (panleukopenia). The vaccine developed for control of Marek’s disease in chickens was the first anticancer vaccine. Veterinarians developed surgical techniques, such as hip-joint replacement and organ transplants, that were later applied successfully to people.

A major challenge to veterinary medicine is adequately attending to the diversity of animal species. Veterinarians address the health needs of domestic animals, including cats, dogs, chickens, horses, cows, sheep, pigs, and goats; wildlife; zoo animals; pet birds; and ornamental fish. The sizes of animals that are treated vary from newborn hamsters to adult elephants, as do their economic values, which range from the undefinable value of pet animal companionship to the high monetary value of a winning racehorse. Medicating this variety of tame and wild animals requires special knowledge and skills.

On the basis of recognition by the World Health Organization (WHO) or the government of a country, there are about 450 veterinary degree programs worldwide. The level of veterinary training varies greatly among the various countries, and only about one-third of these programs designate the degree awarded as a doctor’s degree. Professional training of veterinarians is commonly divided into two phases. The first, or basic science, phase consists of classroom study and laboratory work in the preclinical sciences, including the fields of anatomy, physiology, pathology, pharmacology, toxicology, nutrition, microbiology, and public health. The second phase focuses on the clinical sciences and includes classroom study of infectious and noninfectious diseases, diagnostic and clinical pathology, obstetrics, radiology, anesthesiology, surgery, and practice management and hands-on clinical experience in the college’s veterinary teaching hospital. The clinical experience gives students the opportunity to treat sick animals, perform surgery, and communicate with animal owners. Student activities in the clinical setting are conducted under the supervision of graduate veterinarians on the faculty. Several important opportunities for additional training are available to graduate veterinarians. Internship (one-year) and residency (two-to-five-year) programs enable veterinarians to gain clinical proficiency in one or two medical specialties. Graduate veterinarians can also pursue advanced degree programs. Usually the field of advanced study is medically oriented, but some seek advanced degrees in areas such as business.

Most clinical-practice veterinarians treat only companion animals and usually within the practice’s clinic, or animal hospital. A small proportion treat only food-producing animals or horses, most often by traveling to the location of the animal in a vehicle equipped for veterinary services in the field. Most of the remainder in clinical practice are in mixed practices, which deal with both small animals and large domestic animals such as cattle or horses. Some small-animal practices offer services for special species such as ornamental fish, caged birds, and reptiles. Some practices may limit work to a specific medical area such as surgery, dentistry, dermatology, or ophthalmology. Corporate-owned animal hospitals have increased in number and are often combined with a retail outlet for pet supplies.

Veterinarians in academia administer the basic and clinical science programs of veterinary colleges. In addition, they conduct basic and clinical research, the latter of which may involve application of new instrumentation technologies for diagnosis and treatment of animal diseases. Included are echocardiography, laser lithotripsy, endoscopy, nuclear scintigraphy, ultrasonography, computed tomography (CT) scans, and magnetic resonance imaging (MRI; magnetic resonance).

Veterinary medicine intersects with private industry in such areas as marketing of animal-health products, monitoring of animal health in large commercial animal-production programs, and biomedical research. Veterinary specialists in industry work in the fields of toxicology, laboratory animal medicine, pathology, molecular biology, and genetic engineering. Pharmaceutical companies employ veterinarians in the development, safety testing, and clinical evaluation of drugs, chemicals, and biological products such as antibiotics and vaccines for animals and people.

National and local governments employ veterinarians in those agencies charged with public health, protection of the environment, agricultural research, food and drug safety, food-animal inspection, the health of imported animals, and the humane treatment of animals. Veterinarians working in public-health programs, for example, evaluate the safety of food-processing plants, restaurants, and water supplies. They also monitor and help control animal and human disease outbreaks. The increased threat of bioterrorism has given veterinarians vital roles in the protection of the food supply for animals and people and in early detection of use of zoonotic organisms as weapons. Veterinarians also work in aerospace; e.g., they have been scientific advisers on animal use in the U.S. space program and have been members of U.S. space shuttle crews. Veterinarians in military service perform biomedical research, care for military dogs, and protect troops through food-inspection and communicable-disease monitoring-and-control programs.


A veterinarian (vet) is a medical professional who practices veterinary medicine. They manage a wide range of health conditions and injuries in non-human animals. Along with this, veterinarians also play a role in animal reproduction, health management, conservation, husbandry and breeding and preventive medicine like nutrition, vaccination and parasitic control as well as biosecurity and zoonotic disease surveillance and prevention.


In many countries, the local nomenclature for a veterinarian is a regulated and protected term, meaning that members of the public without the prerequisite qualifications and/or license are not able to use the title. This title is selective in order to produce the most knowledgeable veterinarians that pass these qualifications. In many cases, the activities that may be undertaken by a veterinarian (such as treatment of illness or surgery in animals) are restricted only to those professionals who are registered as a veterinarian. For instance, in the United Kingdom, as in other jurisdictions, animal treatment may only be performed by registered veterinarians (with a few designated exceptions, such as paraveterinary workers), and it is illegal for any person who is not registered to call themselves a veterinarian, prescribe any drugs, or perform treatment.

Most veterinarians work in clinical settings, treating animals directly. These veterinarians may be involved in a general practice, treating animals of all types; they may be specialized in a specific group of animals such as companion animals, livestock, zoo animals or equines; or may specialize in a narrow medical discipline such as surgery, dermatology or internal medicine. As with other healthcare professionals, veterinarians face ethical decisions about the care of their patients. Current debates within the profession include the ethics of certain procedures believed to be purely cosmetic or unnecessary for behavioral issues, such as declawing of cats, docking of tails, cropping of ears and debarking on dogs.

Etymology and nomenclature

The word "veterinary" comes from the Latin veterinae meaning "working animals". "Veterinarian" was first used in print by Thomas Browne in 1646. Although "vet" is commonly used as an abbreviation in all English-speaking countries, the occupation is formally referred to as a veterinary surgeon in the United Kingdom and Ireland and now as a veterinarian in most of the rest of the English-speaking world.


Ancient Indian sage and veterinarian Shalihotra (mythological estimate c. 2350 BCE), the son of a sage, Hayagosha, is considered the founder of veterinary sciences.

The first veterinary college was founded in Lyon, France, in 1762 by Claude Bourgelat. According to Lupton, after observing the devastation being caused by cattle plague to the French herds, Bourgelat devoted his time to seeking out a remedy. This resulted in his founding a veterinary college in Lyon in 1761, from which establishment he dispatched students to combat the disease; in a short time, the plague was stayed and the health of stock restored, through the assistance rendered to agriculture by veterinary science and art.

The Odiham Agricultural Society was founded in 1783 in England to promote agriculture and industry, and played an important role in the foundation of the veterinary profession in Britain. A 1785 Society meeting resolved to "promote the study of Farriery upon rational scientific principles."

The professionalization of the veterinary trade was finally achieved in 1790, through the campaigning of Granville Penn, who persuaded the Frenchman Charles Vial de Sainbel to accept the professorship of the newly established Veterinary College in London. The Royal College of Veterinary Surgeons was established by royal charter in 1844.

Veterinary science came of age in the late 19th century, with notable contributions from Sir John McFadyean, credited by many as having been the founder of modern Veterinary research.

Roles and responsibilities

Veterinarians treat disease, disorder or injury in animals, which includes diagnosis, treatment and aftercare. The scope of practice, specialty and experience of the individual veterinarian will dictate exactly what interventions they perform, but most will perform surgery (of differing complexity).

Unlike in human medicine, veterinarians must rely primarily on clinical signs, as animals are unable to vocalize symptoms as a human would. In some cases, owners may be able to provide a medical history and the veterinarian can combine this information along with observations, and the results of pertinent diagnostic tests such as radiography, CT scans, MRI, blood tests, urinalysis and others.

Veterinarians must consider the appropriateness of euthanasia ("putting to sleep") if a condition is likely to leave the animal in pain or with a poor quality of life, or if treatment of a condition is likely to cause more harm to the patient than good, or if the patient is unlikely to survive any treatment regimen. Additionally, there are scenarios where euthanasia is considered due to the constraints of the client's finances.

As with human medicine, much veterinary work is concerned with prophylactic treatment, in order to prevent problems occurring in the future. Common interventions include vaccination against common animal illnesses, such as distemper or rabies, and dental prophylaxis to prevent or inhibit dental disease. This may also involve owner education so as to avoid future medical or behavioral issues.

Additionally, veterinarians can play important roles in public health and the prevention of zoonoses.

Impact on human medicine

Some veterinarians pursue post-graduate training and enter research careers and have contributed to advances in many human and veterinary medical fields, including pharmacology and epidemiology. Research veterinarians were the first to isolate oncoviruses, Salmonella species, Brucella species, and various other pathogenic agents. Veterinarians were in the forefront in the effort to suppress malaria and yellow fever in the United States. Veterinarians identified the botulism disease-causing agent, developed a widely used anesthetic induction drug, produced an anticoagulant used to treat human heart disease, and developed surgical techniques for humans, such as hip-joint replacement, limb and organ transplants.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1884 2023-08-29 00:08:30

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1888) Ladder


A device used for climbing that has two long pieces of wood, metal, or rope with a series of steps or rungs between them


A ladder is a vertical or inclined set of rungs or steps used for climbing or descending. There are two types: rigid ladders that are self-supporting or that may be leaned against a vertical surface such as a wall, and rollable ladders, such as those made of rope or aluminium, that may be hung from the top. The vertical members of a rigid ladder are called stringers or rails (US) or stiles (UK). Rigid ladders are usually portable, but some types are permanently fixed to a structure, building, or equipment. They are commonly made of metal, wood, or fiberglass, but they have been known to be made of tough plastic.

Historical usages

Ladders are ancient tools and technology. A ladder is featured in a Mesolithic rock painting that is at least 10,000 years old, depicted in the Spider Caves in Valencia, Spain. The painting depicts two humans using a ladder to reach a wild honeybee nest to harvest honey. The ladder is depicted as long and flexible, possibly made out of some sort of grass.


Rigid ladders

Rigid ladders are available in many forms, such as:

* Accommodation ladder, portable steps down the side of a ship for boarding.
* Assault ladder, used in siege warfare to assist in climbing walls and crossing moats.
* Attic ladder, pulled down from the ceiling to allow access to an attic or loft.
* Bridge ladder, a ladder laid horizontally to act as a passage between two points separated by a drop.
* Boarding ladder, a ladder used to climb onto a vehicle. May be rigid or flexible, also boarding step(s), and swim ladder.
* Cat ladder (US chicken ladder), a lightweight ladder frame used on steep roofs to prevent workers from sliding.
* Chicken ladder, a ladder comprising a single central stile with each rung projecting on either side and used by chickens to climb into a coop.
* Christmas tree ladder, a type of boarding ladder for divers which has a single central rail and is open at the sides to allow the diver to climb the ladder while wearing swimfins.
* Counterbalanced ladder, a fixed ladder with a lower sliding part. A system of counterweights is used to let the lower sliding part descend gently when released.
* Extension ladder or "telescopic ladder", a fixed ladder divided into two or more lengths for more convenient storage; the lengths can be slid together for storage or slid apart to expand the length of the ladder; a pulley system may be fitted so that the ladder can be easily extended by an operator on the ground then locked in place using the dogs and pawls. 65 ft (20 m), 50 ft (15 m) and some 35 ft (10 m) extension ladders for fire service use "bangor poles", "tormentor poles" or "stay poles" to help raise, pivot, steady, extend, place, retract and lower them due to the heavy weight.
* Fixed ladder, two side members joined by several rungs; affixed to structure with no moving parts.
* Folding ladder, a ladder in the step ladder style with one or more (usually no more than three) one-way hinges. Ideal for use on uneven ground (e.g. stairs), as a trestle or when fully extended a Fixed ladder. Some variations feature a central one-way hinge with extensible locking legs.
* Hook ladder or pompier ladder, a rigid ladder with a hook at the top to grip a windowsill; used by firefighters.
* Mobile Safety Steps are self-supporting structures that have wheels or castors making them easy to move. They sometimes have a small upper platform and a hand rail to assist in moving up and down the steps.
* Orchard ladder, a three legged step ladder with the third leg made so that it can be inserted between tree branches for fruit picking.
* Platform ladder, a step ladder with a large platform area and a top handrail for the user to hold while working on the platform.
* Retractable ladder, a ladder that looks like a drainpipe but can be deployed instantly when required.
* Roof ladder, a rigid ladder with a large hook at the top to grip the ridge of a pitched roof.
* Sectional ladder, also known as a builder's ladder, has sections that come apart and are interchangeable so that any number of sections can be connected.
* Step ladder, a self-supporting portable ladder hinged in the middle to form an inverted V, with stays to keep the two halves at a fixed angle. Step ladders have flat steps and a hinged back.
* Swim ladder, a ladder used by swimmers to get out of the water, often on boats.
* Telescoping ladder, commonly used to refer to a hybrid between a step ladder and an extension ladder with 360-degree hinges; has three parts and can be taken apart to form two step ladders; e.g. Little Giant.
* Trestle ladder, an "A-Frame"-style ladder with a telescoping center section.
* Turntable ladder, an extension ladder fitted to rotating platform on top of a fire truck.
* Vertically rising ladder, designed to climb high points and facilitate suspending at said high points.
* X-deck ladder, a US patented ladder design that is a combination ladder and scaffold.

Rigid ladders were originally made of wood, but in the 20th century aluminium became more common because of its lighter weight. Ladders with fiberglass stiles are used for working on or near overhead electrical wires, because fiberglass is an electrical insulator. Henry Quackenbush patented the extension ladder in 1867.

Flexible ladders

Rope ladders or Jacob's ladders are used where storage space is extremely limited, weight must be kept to a minimum, or in instances where the object to be climbed is too curved to use a rigid ladder. They may have rigid or flexible rungs. Climbing a rope ladder requires more skill than climbing a rigid ladder, because the ladder tends to swing like a pendulum. Jacob's ladders used on a ship are used mostly for emergencies or for temporary access to the side of a ship. Steel and aluminum wire ladders are sometimes used in vertical caving, having developed from rope ladders with wooden rungs. Flexible ladders are also sometimes used as swim ladders on boats.


Dissipative ladders are portable ladders built to ESD (Electrostatic Discharge) standard. Electrostatic Discharge is a natural occurrence in which electricity is passed through the body, or other conductors, and discharges onto some object. For example, the shock sometimes felt when a doorknob is touched is an ESD. This natural occurrence is a very important topic in the field of electronics assembly due to the costly damage ESDs can cause to sensitive electronic equipment. Dissipative ladders are ladders with controlled electrical resistance: the resistance slows the transfer of charge from one point to another, offering increased protection during ESD events: ≥105 and < 1012 Ω / square.
Boarding and pool ladders, also swim ladders and dive ladders. A ladder may be used on the side or stern of a boat, to climb into it from the water, and in a swimming pool, to climb out and sometimes in. Swimming pool ladders are usually made from plastic, wood or metal steps with a textured upper surface for grip and metal rails at the sides to support the steps and as handrails for the user, and are usually fixed in place. Boarding ladders for boats may be fixed, but are usually portable, and often fold away when not in use to avoid drag when under way. Boarding ladders may also be used for other types of vehicle, or boarding steps which are supported directly by the vehicle structure.

Assault ladders:


The most common injury made by ladder climbers is bruising from falling off a ladder, but bone fractures are common and head injuries are also likely, depending on the nature of the accident. Ladders can cause injury if they slip on the ground and fall. To avoid this, they tend to have plastic feet or base pads which increase friction with the ground. However, if the plastic is badly worn, the aluminium may contact the ground increasing the chance of an accident. Ladder stabilizers are also available to increase the ladder's grip on the ground. One of the first ladder stabilizers or ladder feet was offered in 1936 and today they are standard equipment on most large ladders.

A ladder standoff, or stay, is a device fitted to the top of a ladder to hold it away from the wall. This enables the ladder to clear overhanging obstacles, such as the eaves of a roof, and increases the safe working height for a given length of ladder because of the increased separation distance of the two contact points at the top of the ladder.

It has become increasingly common to provide anchor points on buildings to which the top rung of an extension ladder can be attached, especially for activities like window cleaning, especially if a fellow worker is not available for "footing" the ladder. Footing occurs when another worker stands on the lowest rung and so provides much greater stability to the ladder when being used. However footing a ladder should be seen as a last resort for a safe placement. The anchor point is usually a ring cemented into a slot in the brick wall to which the rungs of a ladder can be attached using rope for example, or a carabiner.

If a leaning ladder is placed at the wrong angle, the risk of a fall is greatly increased. The safest angle for a ladder is 75.5°; if it is too shallow, the bottom of the ladder is at risk of sliding, and if it is too steep, the ladder may fall backwards. This angle is achieved by following the 4 to 1 rule for a ladder placed on a vertical wall: for every four feet of vertical height, the ladder foot should move one foot from the wall. Both scenarios can cause significant injury, and are especially important in industries like construction, which require heavy use of ladders.

Ladder classes

The European Union and the United Kingdom established a ladder certification system – ladder classes – for any ladders manufactured or sold in Europe. The certification classes apply solely to ladders that are portable such as stepladders and extension ladders and are broken down into three types of certification. Each ladder certification is colour-coded to indicate the amount of weight the ladder is designed to hold, the certification class and its use. The color of the safety label specifies the class and use.

Class 1 ladder – for heavy-duty industrial uses, maximum load of 175 kg. Colour-coded blue to identify.
Class EN141 ladders – for commercial uses, maximum load of 150 kg. No specific colour code..
Class III ladders – for light, domestic uses, maximum load of 125 kg. Colour-coded red to identify.

Society and culture

A common superstition in English-speaking countries is that walking under a ladder is seen as bad luck. Some sources claim that this stems from the image of a ladder being propped up against a wall looking similar to a gallows, while others attribute it to ancient Egyptian traditions involving pyramids and triangles representing the trinity of the gods, and passing through the triangular shape made by a ladder against a wall was seen as desecration. Ladders have also been linked to the crucifixion of Christ, with author and scientist Charles Panati noting that many believe a ladder rested against the crucifix that Christ hung from, making it a symbol of wickedness, betrayal and death. In comedic children's media, the image of a character walking under a ladder being the cause or result of bad luck has become a common trope.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1885 2023-08-30 00:30:56

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1889) Flashlight


Flashlight is a small light that is held in the hand and usually gets its power from batteries.

Also called, especially British, torch . a small, portable electric lamp powered by dry batteries, LEDs, or a tiny generator.


A flashlight (US, CA) or torch (UK, AU) is a portable hand-held electric lamp. Formerly, the light source typically was a miniature incandescent light bulb, but these have been displaced by light-emitting diodes (LEDs) since the mid-2000s. A typical flashlight consists of the light source mounted in a reflector, a transparent cover (sometimes combined with a lens) to protect the light source and reflector, a battery, and a switch, all enclosed in a case.

The invention of the dry cell and miniature incandescent electric lamps made the first battery-powered flashlights possible around 1899. Today, flashlights use mostly light-emitting diodes and run on disposable or rechargeable batteries. Some are powered by the user turning a crank, shaking the lamp, or squeezing it. Some have solar panels to recharge the battery. Flashlights are used as a light source outdoors, in places without permanently installed lighting, during power outages, or when a portable light source is needed.

In addition to the general-purpose, hand-held flashlight, many forms have been adapted for special uses. Head- or helmet-mounted flashlights designed for miners and campers leave both hands free. Some flashlights can be used under water or in flammable atmospheres.


Early flashlights ran on zinc–carbon batteries, which could not provide a steady electric current and required periodic "rest" to continue functioning. Because these early flashlights also used energy-inefficient carbon-filament bulbs, "resting" occurred at short intervals. Consequently, they could be used only in brief flashes, hence the common North American name "flashlight".


The first dry cell battery was invented in 1887. Unlike previous batteries, it used a paste electrolyte instead of a liquid. This was the first battery suitable for portable electrical devices, as it did not spill or break easily and worked in any orientation. The first mass-produced dry cell batteries came in 1896, and the invention of portable electric lights soon followed. Portable hand-held electric lights offered advantages in convenience and safety over (combustion) torches, candles and lanterns. The electric lamp was odorless, smokeless, and emitted less heat than combustion-powered lighting. It could be instantly turned on and off, and avoided fire risk.

On January 10, 1899, British inventor David Misell obtained U.S. Patent No. 617,592, assigned to American Electrical Novelty and Manufacturing Company. This "electric device" designed by Misell was powered by "D" batteries laid front to back in a paper tube with the light bulb and a rough brass reflector at the end. The company donated some of these devices to the New York City police, who responded favorably to them.

Carbon-filament bulbs and fairly crude dry cells made early flashlights an expensive novelty, with low sales and low manufacturer interest. Development of the tungsten-filament lamp in 1904, with three times the efficacy of carbon filament types, and improved batteries, made flashlights more useful and popular. The advantage of instant control, and the absence of flame, meant that hand-held electric lights began to replace combustion-based lamps such as the hurricane lantern. By 1922 several types were available; the tubular hand-held variety, a lantern style that could be set down for extended use, pocket-size lamps for close work, and large reflector searchlight-type lamps for lighting distant objects. In 1922 there were an estimated 10 million flashlight users in the United States, with annual sales of renewal batteries and flashlights at $20 million, comparable to sales of many line-operated electrical appliances. Flashlights became very popular in China; by the end of the 1930s, 60 companies made flashlights, some selling for as little as one-third the cost of equivalent imported models. Miniature lamps developed for flashlight and automotive uses became an important sector of the incandescent lamp manufacturing business.

LED flashlights were made in the early 2000s. Maglite made their first LED flashlight in 2006.


Incandescent flashlights use incandescent light bulbs, which consists of a glass bulb and a tungsten filament. The bulbs are under vacuum or filled with argon, krypton, or xenon. Some high-power incandescent flashlights use a halogen lamp where the bulb contains a halogen gas such as iodine or bromine to improve the life and efficacy of the bulb. In all but disposable or novelty flashlights, the bulb is user-replaceable; the bulb life may be only a few hours.

The light output of an incandescent lamp in a flashlight varies widely depending on the type of lamp. A miniature keychain lamp produces one or two lumens. A two-D-cell flashlight using a common prefocus-style miniature lamp produces on the order of 15 to 20 lumens of light and a beam of about 200 candlepower. One popular make of rechargeable focusing flashlight uses a halogen lamp and produces 218 lumens. By comparison, a 60-watt household incandescent lamp will produce about 900 lumens. The luminous efficacy or lumens produced per watt of input of flashlight bulbs varies over the approximate range of 8 to 22 lumens/watt, depending on the size of the bulb and the fill gas, with halogen-filled 12-volt lamps having the highest efficiency.


Powerful white-light-emitting diodes (LEDs) have mostly replaced incandescent bulbs in practical flashlights. LEDs existed for decades, mainly as low-power indicator lights. In 1999, Lumileds Corporation of San Jose, California, introduced the Luxeon LED, a high-power white-light emitter. This made possible LED flashlights with power and running time better than incandescent lights. The first Luxeon LED flashlight was the Arc LS, designed in 2001. White LEDs in 5 mm diameter packages produce only a few lumens each; many units may be grouped together to provide additional light. Higher-power LEDs, drawing more than 100 milliamperes each, simplify the optical design problem of producing a powerful and tightly controlled beam.

LEDs can be significantly more efficient than incandescent lamps, with white LEDs producing on the order of 100 lumens for every watt, compared to 8-10 lumens per watt of small incandescent bulbs. An LED flashlight has a longer battery life than an incandescent flashlight with comparable output. LEDs are also less fragile than glass lamps. LED lamps have different spectra of light compared to incandescent sources, and are made in several ranges of color temperature and color rendering index. Since the LED has a long life compared to the usual life of a flashlight, very often it is permanently installed. Flashlights made for an incandescent lamp can often be upgraded to a more efficient LED lamp.

LEDs generally must have some kind of control to limit current through the diode. Flashlights using one or two disposable 1.5-volt cells require a boost converter to provide the higher voltage required by a white LED, which needs around 3.4 volts to function. Flashlights using three or more dry cells may only use a resistor to limit current. Some flashlights electronically regulate the current through the LEDs to stabilize light output as the batteries discharge. LEDs maintain nearly constant color temperature regardless of input voltage or current, while the color temperature of an incandescent bulb rapidly declines as the battery discharges, becoming redder and less visible. Regulated LED flashlights may also have user-selectable levels of output appropriate to a task, for example, low light for reading a map and high output for checking a road sign. This would be difficult to do with a single incandescent bulb since efficacy of the lamp drops rapidly at low output.

LED flashlights may consume 1 watt or much more from the battery, producing heat as well as light. In contrast to tungsten filaments, which must be hot to produce light, both the light output and the life of an LED decrease with temperature. Heat dissipation for the LED often dictates that small, high-power LED flashlights have aluminium or other high heat-conductivity bodies, reflectors, and other parts to dissipate heat; they can become warm during use.

Light output from LED flashlights varies even more widely than for incandescent lights. "Keychain" type lamps operating on button batteries, or lights using a single 5 mm LED, may only produce a few lumens. Even a small LED flashlight operating on an AA cell, but equipped with an LED, can emit 100 lumens. The most powerful LED flashlights produce more than 100,000 lumens and may use multiple LEDs.

LEDs are highly efficient at producing colored light compared with incandescent lamps and filters. An LED flashlight may contain different LEDs for white and colored light, selectable by the user for different purposes. Colored LED flashlights are used for signalling, special inspection tasks, forensic examination, or to track the blood trail of wounded game animals. A flashlight may have a red LED intended to preserve dark adaptation of vision. Ultraviolet LEDs may be used for inspection lights, for example, detecting fluorescent dyes added to air conditioning systems to detect leakage, examining paper currency, or checking UV-fluorescing marks on laundry or event ticket holders. Infrared LEDs can be used for illuminators for night-vision systems. LED flashlights may be specified to be compatible with night vision devices.


A less common type of flashlight uses a high-intensity discharge lamp (HID lamp) as the light source. An HID gas discharge lamp uses a mixture of metal halide salts and noble gas as a filler. HID lamps produce more light than a traditional incandescent flashlight using the same amount of electricity, though not as much as high power LEDs. The lamp lasts longer and is more shock resistant than a regular incandescent bulb, since it lacks the relatively fragile electrical filament found in incandescent bulbs. However, they are much more expensive than incandescent, due to the ballast circuit required to start and operate the lamp. An HID lamp requires a short warm-up time before it reaches full output.


LEP stands for Laser Excited Phospor. LEP modules are used in professional grade flashlights. Unlike LED or HID, the light source is a blue laser. With the first mainstream LEP flashlight available in 2018, there are currently a few dozen LEP flashlights, mainly from China. There are currently 2 types of LEP modules, namely a mirror-type as well as a shine-though type. The former one using a mirror to shine the blue laser onto a laser of phosphor, which then turns the blue light into a white-ish looking beam. The latter is having the blue laser located behind a translucent layer of phospor, and emits the laser through the phosphor layer to turn it into a white-ish beam. Besides these 2 differences, the mirror-type is built inside a plastic module, while the shine-through models are usually built with a copper/aluminum shell, and much smaller than the plastic type. They are classes as Class 1 lasers, up to Class 3 lasers. In many countries, Class 3 lasers are only allowed to be used by professionals. However, flashlights like the Fenix TK30, Fenix HT30, are sold worldwide, as being Class 1 laser flashlights, and therefore available to the general public. Some lesser known flashlight brands sell LEP flashlights online, and often don't use a laser classification.


Certain accessories for a flashlight allow the color of the light to be altered or allow light to be dispersed differently. Translucent colored plastic cones slipped over the lens of a flashlight increase the visibility when looking at the side of the light. Such marshalling wands are frequently used for directing automobiles or aircraft at night. Colored lenses placed over the end of the flashlight are used for signalling, for example, in railway yards. Colored light is occasionally useful for hunters tracking wounded game after dusk, or for forensic examination of an area. A red filter helps preserve night vision after the flashlight is turned off, and can be useful to observe animals (such as nesting loggerhead sea turtles) without disturbing them.

Detachable light guides, consisting of rigid, bent plastic rods or semirigid or flexible tubes containing optical fibers, are available for some flashlights for inspection inside tanks, or within walls or structures; when not required, the light guide can be removed and the light used for other purposes.

Formats and specialized designs

A penlight is a small, pen-sized flashlight, often containing two AA or AAA batteries. In some types, the incandescent light bulb has an integral lens that focuses the light, so no reflector is built into the penlight. Others use incandescent bulbs mounted in reflectors. LED penlights are becoming increasingly common. Low-cost units may be disposable with no provision to replace batteries or bulbs and are sometimes imprinted with advertising for promotional purposes.

A headlamp is designed to be worn on the head, often having separate lamp and battery components. The battery pack may be attached at the back of the head or in a pocket to improve balance. Headlamps leave the users' hands' free. A headlamp can be clipped to the brim of a hat, or built to mount on a hard hat, instead of using straps; other types resemble eyeglass frames. Similar to the headlamp, an angle-head flashlight emits light perpendicular to the length of the battery tube; it can be clipped to a headband, belt, or webbing or set on a flat surface. Some types allow the user to adjust the angle of the head. The Fulton MX991/U Flashlight was an angle-head flashlight issued to US military personnel; similar style lights remain popular.

Tactical lights are sometimes mounted to a handgun or rifle. They allow momentary illumination of a target. They are small enough to be easily rail-mounted to a gun barrel. Tactical lights must withstand the impact of recoil and must be easily controlled while holding the weapon.

Although most flashlights are designed for user replacement of the batteries and the bulb as needed, fully sealed disposable flashlights, such as inexpensive keyring lights, are made. When the batteries are depleted or the bulb fails, the entire product is discarded.

Diving lamps must be watertight under pressure and are used for night diving and supplemental illumination where surface light cannot reach. The battery compartment of a dive lamp may have a catalyst to recombine any hydrogen gas emitted from the battery since gas cannot be vented in use.

People working in hazardous areas with significant concentrations of flammable gases or dusts, such as mines, engine rooms of ships, chemical plants, or grain elevators, use "nonincendive", "intrinsically safe", or "explosion-proof" flashlights constructed so that any spark in the flashlight is not likely to set off an explosion outside the light. The flashlight may require approval by an authority for the particular service and particular gases or dusts expected. The external temperature rise of the flashlight must not exceed the autoignition point of the gas, so substitution of more powerful lamps or batteries may void the approval.

Flashlight in the shape of a gun (mid-20th century) from the permanent collection of the Museo del Objeto del Objeto
Inspection flashlights have permanently mounted light guides containing optical fibers or plastic rods. Another style has a lamp mounted at the end of a flexible cable, or a semirigid or articulated probe. Such lamps are used for inspection inside tanks, or inside structures such as aircraft. Where used for inspecting the interior of tanks containing flammable liquids, the inspection lights may also be rated as flame-proof (explosion-proof) so that they cannot ignite liquids or vapors.

Otoscopes and ophthalmoscopes are medical instruments that combine a hand-held light source and magnifying lenses for examination of the ear canal and eyes, respectively.

Aboard naval ships, battle lanterns may be used as emergency portable lighting. Installed in major compartments of the ship, a battle lantern can be detached from its mounting and used as portable lighting in the event primary lighting is out of service. Battle lanterns may use either incandescent or LED lamps and may have either disposable primary or rechargeable batteries.

Many flashlights are cylindrical in design, with the lamp assembly attached to one end. However, early designs came in a variety of other shapes. Some resembled candlesticks, with a bulb mounted at the top of a battery tube fixed to a flat base, with a handle. Many resembled lanterns, consisting of a battery box with a handle and the lamp and reflector attached to the front. Electric lanterns are used for lighting the broad area immediately around the lantern, as opposed to forming a narrow beam; they can be set down on a level surface or attached to supports. Some electric lanterns use miniature fluorescent lamps for higher efficiency than incandescent bulbs. Portable hand-held electric spotlights can provide larger reflectors and lamps and more powerful batteries than tubular flashlights meant to fit in a pocket.

Multifunction portable devices may include a flashlight as one of their features, for example, a portable radio/flashlight combination. Many smartphones have a button or software application available to turn up their screen backlights to full intensity or to switch on the camera flash or video light, providing a "flashlight" function.

In addition to utilitarian flashlights, novelty, toy, and ornamental portable electric lights have been made in a myriad of shapes; in the 1890s, one of the earliest portable battery light applications was a type of novelty porcelain tie pin with a concealed bulb and battery.

Power sources:


The most common power source for flashlights is the battery. Primary battery (disposable) types used in flashlights include button cells, carbon-zinc batteries in both regular and heavy duty types, alkaline, and lithium.

Secondary, rechargeable types include lead-acid batteries, NiMH, NiCd batteries and lithium-ion batteries. The choice of batteries plays a determining role in the size, weight, run time, and shape of the flashlight. Flashlight users may prefer a common battery type to simplify replacement.

Primary cells are most economical for infrequent use. Some types of lithium primary cell can be stored for years with less risk of leakage compared with zinc-type batteries. Long storage life is useful where flashlights are required only in emergencies. Lithium primary batteries are also useful at lower temperatures than zinc batteries, all of which have water-based electrolytes. Lithium primary batteries have a lower internal resistance than zinc primary batteries, so are more efficient in high-drain flashlights.

Flashlights used for extended periods every day may be more economically operated on rechargeable (secondary) batteries. Flashlights designed for rechargeable batteries may allow charging without removing the batteries; for example, a light kept in a vehicle may be trickle-charged and always ready when needed. Some rechargeable flashlights have indicators for the state of charge of the battery. Power-failure lights are designed to keep their batteries charged from a wall plug and to automatically turn on after an AC power failure; the power-failure light can be removed from the wall socket and used as a portable flashlight. Solar powered flashlights use energy from solar cells to charge an on-board battery for later use.

Mechanical power

One type of mechanically powered flashlight has a winding crank and spring connected to a small electrical generator (dynamo). Some types use the dynamo to charge a capacitor or battery, while others only light while the dynamo is moving. Others generate electricity using electromagnetic induction. They use a strong permanent magnet that can freely slide up and down a tube, passing through a coil of wire as it does. Shaking the flashlight charges a capacitor or a rechargeable battery that supplies current to a light source. Such flashlights can be useful during an emergency, when utility power and batteries may not be available. Dynamo-powered flashlights were popular during the Second World War since replacement batteries were difficult to find.


At least one manufacturer makes a rechargeable flashlight that uses a supercapacitor to store energy. The capacitor can be recharged more rapidly than a battery and can be recharged many times without loss of capacity; however, the running time is limited by the relative bulk of capacitors compared to electrochemical batteries.

Reflectors and lenses

A reflector with an approximately parabolic shape concentrates the light emitted by the bulb into a directed beam. Some flashlights allow the user to adjust the relative position of the lamp and reflector, giving a variable-focus effect from a wide floodlight to a narrow beam. Reflectors may be made of polished metal, glass, or plastic with an aluminized reflective finish. Some manufacturers use a pebbled or "orange peel", instead of a smooth reflector, to improve the uniformity of the light beam emitted. Where multiple LEDs are used, each one may be put in its own parabolic reflector. Flashlights using a "total internal reflection" assembly have a transparent optical element (light pipe) to guide light from the source into a beam; no reflector surface is required. For a given size of light source, a larger reflector or lens allows a tighter beam to be produced, while capturing the same fraction of the emitted light. Some flashlights use Fresnel lenses, which allow the weight of the lens to be reduced.

The reflector may have a flat transparent cover to keep out dirt and moisture, but some designs have a plastic or glass "bulls-eye" lens to form a concentrated beam. The lens or reflector cover must resist impacts and the heat of the lamp, and must not lose too much of the transmitted light to reflection or absorption. Very small flashlights may not have a reflector or lens separate from the lamp. Some types of penlight bulbs or small LEDs have a built-in lens.

A reflector forms a narrow beam called the "throw" in hobbyist parlance, while light emitted forward misses the reflector and forms a wide flood or "spill" of light. Because LEDs emit most light in a hemisphere, lens lights with the LED facing forward or reflector lights with it facing backwards radiate less spill. Variable focus "zoom" or "flood to throw" lights may move the reflector or lens or they may move the emitter; moving the emitter presents the designer with the problem of maintaining heat dissipation for the LED.

Control switch

The original 1890s flashlights used a metal ring around the fiber body of the flashlight as one contact of a switch; the second contact was a movable metal loop that could be flipped down to touch the ring, completing the circuit. A wide variety of mechanical switch designs using slide switches, rocker switches, or side-mounted or end-mounted pushbuttons has been used in flashlights. A common combination is a slide switch that allows the light to be left on for an extended time, combined with a momentary button for intermittent use or signalling. (On earlier models, the button was a switch and the slider simply locked the button down.) Since voltages and currents are low, switch design is limited only by the available space and desired cost of production. Switches may be covered with a flexible rubber boot to exclude dirt and moisture and may be backlit for easy location. Another common type of switch relies on twisting the head of the light. Weapon-mounted lights may have remote switches for convenience in operation.

Electronic controls allow the user to select variable output levels or different operating modes such as pre-programmed flashing beacon or strobe modes. Electronic controls may be operated by buttons, sliders, magnets, rotating heads, or rotating control rings. Some models of flashlight include an acceleration sensor to allow them to respond to shaking, or to select modes based on what direction the light is held when switched on. At least one manufacturer allows user programming of the features of the flashlight through a USB port. An electronic control may also provide an indication of remaining battery capacity, voltage, or provide information regarding recharging or automatic step-down of brightness as the battery nears full discharge.


Early flashlights used vulcanized fiber or hard rubber tubes with metal end caps. Many other materials including drawn steel, plated brass, copper, or silver, and even wood and leather have been used. Modern flashlights are generally made of plastic or aluminum. Plastics range from low-cost polystyrene and polyethylene to more complex mixtures of ABS or glass-reinforced epoxies. Some manufacturers have proprietary plastic formulations for their products. A desirable plastic for manufacturing flashlights allows for ease of molding and adequate mechanical properties of the finished flashlight case. Aluminum, either plain, painted or anodized, is a popular choice. It is electrically conductive, can be easily machined, and dissipates heat well. Several standard alloys of aluminum are used. Other metals include copper, stainless steel, and titanium, which can be polished to provide a decorative finish. Zinc can be die-cast into intricate shapes. Magnesium and its alloys provide strength and heat dissipation similar to aluminum with less weight, but they corrode easily.

Metals may be drawn into a tubular shape, or tubular extruded stock can be machined to add threads for the head and tail cap, knurling for grip, and decorative and functional flats or holes in the body. LED flashlights may have cooling fins machined into their metal cases. Plastics are often injection molded into nearly final shape, requiring only a few more process steps to complete assembly. Metal cases provide better heat dissipation for the LED, but plastics are not electrically conductive and may resist corrosion and wear.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1886 2023-08-31 00:22:46

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1890) Wakefulness


Wakefulness is a daily recurring brain state and state of consciousness in which an individual is conscious and engages in coherent cognitive and behavioral responses to the external world. Being awake is the opposite of being asleep, in which most external inputs to the brain are excluded from neural processing.


Unlike being awake, a vigilant consciousness, sleep corresponds to a withdrawal of cathexis from the outside world accompanied by a suspension of motor activity. It is an active phenomenon, and although at the beginning of life the opposition wakefulness/sleep is closely dependent upon that of satisfactions and needs; wishes, the capacity for regression, and the nature of the infant's relations to the mother soon modify this binary rhythm. In the waking state, excitation begins with sensory perception and in a sense traverses the psychic apparatus to emerge any motility; whereas during sleep the reverse happens: excitation passes from ideation to sensory perception, the dream.

Sigmund Freud approached the issue of waking and sleep through the analysis of dreams. In The Interpretation of Dreams (1900a), he advanced the hypothesis that dreams are the guardians of sleep. Unconscious excitation, linked to previous day's residues, is liable to disturb sleep. The dream is responsible for bringing this free energy under the control of the Preconscious; it diverts this energy, serves as a safety valve, and thus, with a minimal effort of vigilance, ensures sleep.

Freud did not modify this hypothesis, but later did flesh it out, most notably in the article "A Metapsychological Supplement to the Theory of Dreams" (1916-1917 [1915]), where he introduces the concept of a wish to sleep emanating from the ego, a veritable sleep drive that impels the sleeper to return to intrauterine life. Sleep must be understood as a period of withdrawal toward primary narcissism: The mind renounces most of its acquisitions via a return to its developmental starting point as a way of reliving of its stay in the maternal body, some of the conditions of which are reproduced in sleep. It is as if a kind of inversion happens in sleep: The subject turns toward his or her inner world by almost totally withdrawing interest in the outer world of waking reality.

As Freud pointed out in the introduction to his "supplement," sleep, like mourning or being in love, can be considered the normal prototype of a pathological state. Regression and backward steps in development are observed. There are two types of regression. First, a temporal regression involving the organization of the ego, which, through this step backward, moves closer to the id. Second, a regression of libidinal development at the level of the drives which goes so far as to restore primary narcissism during sleep. Associated with a relaxation of repression during sleep, which is conducive to the emergence of the Id's drive energies, this state leads to the formation of dreams through hallucinatory wish-fulfillments. The dreamer is only interested in external reality to the degree it may threaten to bring about an end to the sleeping state by awakening.

After Freud, and until the early 1950s, this conception of the opposition sleep waking remained unchanged, and made enriched by concepts such as Bertram D. Lewin's 1949 postulation of the "screen dream," the result of introjecting the good maternal breast, which opens up "the dream space" and actualizes the matrix in which the dream's binding activity can occur. In 1953, when electroencephalographic images revealed the alternation between periods of slow sleep (also called non-rapid eye movement, or NREM sleep), which has a reparative function, and periods of paradoxical sleep (or REM sleep), in which dreams occur, attempts were made to distinguish between the somatic and psychic aspects of hypnic phenomena. As André Green emphasized, it appears to be essential to not transpose concepts from one domain to the other. However, it is both legitimate and productive to explore points of convergence between the two.

Authors do agree that sleep plays an organizing role in the case of both the physiological paradoxical sleep, and the psychological dreams. Dream phenomena seem to have binding functions: maintaining the continuity of sleep, connecting waking mental life to sleeping mental life, and integrating lived experiences by binding them to libidinal needs. Masud Khan called this linking function the "capacity for dreaming," and Didier Houzel suggested that this involves a process of stabilization, not in the form of a return to a fixed energy level of zero, but rather as a form of "structural stability," that is, a dynamic equilibrium that assumes constant exchange with the environmental milieu.


Wakefulness is a daily recurring brain state and state of consciousness in which an individual is conscious and engages in coherent cognitive and behavioral responses to the external world.

Being awake is the opposite of being asleep, in which most external inputs to the brain are excluded from neural processing.

Effects upon the brain

The longer the brain has been awake, the greater the synchronous firing rates of cerebral cortex neurons. After sustained periods of sleep, both the speed and synchronicity of the neurons firing are shown to decrease.

Another effect of wakefulness is the reduction of glycogen held in the astrocytes, which supply energy to the neurons. Studies have shown that one of sleep's underlying functions is to replenish this glycogen energy source.

Maintenance by the brain

Wakefulness is produced by a complex interaction between multiple neurotransmitter systems arising in the brainstem and ascending through the midbrain, hypothalamus, thalamus and basal forebrain. The posterior hypothalamus plays a key role in the maintenance of the cortical activation that underlies wakefulness. Several systems originating in this part of the brain control the shift from wakefulness into sleep and sleep into wakefulness. Histamine neurons in the tuberomammillary nucleus and nearby adjacent posterior hypothalamus project to the entire brain and are the most wake-selective system so far identified in the brain. Another key system is that provided by the orexins (also known as hypocretins) projecting neurons. These exist in areas adjacent to histamine neurons and like them project widely to most brain areas and associate with arousal. Orexin deficiency has been identified as responsible for narcolepsy.

Research suggests that orexin and histamine neurons play distinct, but complementary roles in controlling wakefulness with orexin being more involved with wakeful behavior and histamine with cognition and activation of cortical EEG.

It has been suggested the fetus is not awake, with wakefulness occurring in the newborn due to the stress of being born and the associated activation of the locus coeruleus.

Additional Information

Sleep is an important part of your overall health and quality of life. How well you sleep affects how well you feel when you’re awake.

Both the length and quality of your sleep are important. Most people spend nearly a third of their lives sleeping, and this is necessary for good productivity and health.

Too little or too much sleep can have adverse health effects and impact your quality of life. Plus, some chronic conditions that cause altered sleep patterns may get worse from lack of sleep, which could result in a shortened life expectancy.

But it is possible to get your sleep back on track or improve the quality of sleep you get each night. Read on for more about the benefits of sleep, sleep disorders, and ways to get a better sleep.

What are the benefits of sleep?

Sleep is important. When you’re asleep, your body replenishes and repairs itself, both mentally and physically. It needs this time to:

* repair muscles
* consolidate memories
* release hormones that maintain growth and digestion

Good-quality sleep helps:

* control your appetite
* support your immune system
* promote good overall health

Many adults are chronically sleep-deprived from going to bed too late or waking up too early.

Getting too little high-quality sleep can leave you feeling fatigued, unable to concentrate, and mentally foggy. It can also raise your risk of accidental injury and certain health conditions.

The amount of sleep you need depends on your age. Children and teens generally need more sleep than adults.

For most adults, the National Heart, Lung, and Blood Institute recommends getting 7 to 8 hours of sleep per night. Getting too little or too much (typically defined as more than 10 hours per night on most nights) can lead to health concerns.

Stages of sleep

Your sleep cycle can be broken into two main types of sleep: nonrapid eye movement (NREM) and rapid eye movement (REM) stages.

NREM stages typically make up 75 to 80 percentTrusted Source of your time asleep. Most adults will enter sleep from a drowsy state via NREM sleep.

NREM sleep is divided into three substages:

* stage N1
* stage N2
* stage N3

Older research had identified four stages of NREM sleep; however, experts currently combine the third NREM stage and the former fourth stage as stage N3.

Here’s more about the three NREM stages:

* Stage N1. This is the typical transition from wakefulness to sleep. Is the lightest stage of sleep; people awakened from it usually don’t realize they were actually asleep. Stage N1 sleep typically accounts for 5 to 10 percent or less of the total sleep time in young adults
* Stage N2. This generally comprises the largest percentage of total sleep time in middle-age adults, typically 45 to 55 percent of the night
* Stage N3. This is frequently referred to as “deep sleep” or “slow wave sleep.” During N3 sleep, blood flow to your muscles increases, growth hormones are released, and tissues can repair themselves. Stage N3 typically accounts for 10 to 20 percent of the total sleep time in young to middle-age adults and decreases with age. It tends to occur more in the first half of the night, particularly at the beginning of the night, and it’s often more difficult to arouse sleepers from, compared with stages N1 and N2.

REM sleep has typically been associated with vivid dreaming, based on early studies in which patients were awoken out of REM sleep. REM sleep typically accounts for less than a quarter of total sleep time and plays an important role in memory consolidation.

Sleep disorders

Some people have sleep disorders that make it difficult to get good a quantity and quality of sleep. Sleep disorders include:

* insomnia
* sleep apnea
* circadian rhythm disorders
* parasomnias


Insomnia is a common condition characterized by difficulty falling asleep or staying asleep or waking up too early.

You may experience insomnia for several reasons. Common causes include:

* stress
* anxiety
* an inconsistent sleep schedule
* overall poor “sleep hygiene”

Insomnia may also be an underlying component of depression or generalized anxiety, which often requires treatment.

Obstructive sleep apnea (OSA)

OSA, often referred to as sleep apnea, occurs when your airways briefly collapse while you’re sleeping. This interrupts (or obstructs) your breathing.

OSA can potentially happen multiple times per night. It can wake you up suddenly and cause stress, resulting in poor sleep, though some people aren’t aware they’re waking up during the night.

Symptoms may include:

* fatigue
* headaches
* snoring

Sleep apnea can have adverse effects on your long-term health, so it’s important to contact a doctor if you think you’re experiencing OSA.

Circadian rhythm disorders

Circadian rhythm disorders occur when your sleep schedule becomes irregular. The most common type of circadian rhythm sleep disorder is called “shift work disorder” or “jet lag“

People who work during the night are at risk of this condition. It occurs when you feel tired at night while you’re working, but you have difficulty sleeping during the day when you’re not working.

Jet lag can also disrupt your sleep rhythms.


Parasomnia is a catchall term for strange and unusual behaviors that people experience prior to falling asleep, while asleep, or during the arousal period between sleep and wakefulness. These behaviors vary considerably in terms of characteristics, severity, and frequency.

Parasomnias include:

* sleepwalking
* talking during sleep
* grinding your teeth during sleep
* having nightmares

Tips for sleeping well

Sleeping well is necessary for good health. But for many people, it’s hard to do. Try these simple strategies to enjoy better quality sleep.

Get treatment for sleep disorders

If you suspect you have insomnia, sleep apnea, or another sleep disorder, talk with your doctor. Many sleep disorders can be managed through lifestyle changes or other treatments.

For example, your doctor may advise you to:

* Change your sleep environment or habits.
* Practice meditation or other relaxation strategies.
* Take prescription medications.
* Undergo a sleep study, known as a polysomnogram, to further evaluate the cause of your sleep disturbance.

OSA can be treated with a continuous positive airway pressure (CPAP) machine.

This is a noninvasive ventilator that helps keep your airways open while you sleep. You’ll wear a mask that allows pressured air to be delivered to your airways.

Practice healthy sleep hygiene

Healthy sleep habits can help you fall asleep, stay asleep, or enjoy better quality sleep.

For example, a consistent sleep schedule is important. Try to go to bed and wake up at the same times each day, even on weekends and holidays.

Making your bedroom more sleep-appropriate and comfortable can also help. Take steps to keep it dark, cool, comfortable, and quiet, such as the following:

* Consider limiting indoor sources of light, buying dark curtains, and using earplugs.
* Update your mattress, pillows, and bedding as needed.
* Limit use of screens (TV, phone, tablet, or computer) 30 to 60 minutes before sleep.
* Shop our expert-verified products for achieving deeper sleep.

Developing a pre-sleep routine can also help prepare your body and mind for sleep. This routine should include relaxing activities, such as:

* taking a warm bath
* drinking herbal tea
* reading a calming book
* listening to calming music
* writing in a journal
* practicing restorative yoga
* meditating

Avoid loud noises, bright lights, glowing computer screens, and other stimulating things before bedtime.

Since stress often causes sleep deprivation, efforts to reduce stress are also important. For example, consider:

* simplifying your lifestyle
* setting priorities
* delegating tasks
* taking regular breaks

Prioritize self-care by eating a well-balanced diet, getting regular exercise, and making time for activities you enjoy.

It may also help to:

* Avoid caffeine, especially late in the day.
* Avoid alcohol, which can disrupt sleep stages.
* Don’t drink too many liquids at night to lessen your need for bathroom trips.
* Avoid exercise late in the day.

Avoid daytime naps, or limit them to 30 minutes or fewer.

If these lifestyle changes don’t help you get the sleep you need, talk with a healthcare professional.

You may have an underlying health condition that’s keeping you awake at night. A doctor can recommend next steps and strategies to improve your sleep.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1887 2023-09-01 00:07:23

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1891) Telemarketing


Telemarketing is the direct marketing of goods or services to potential customers over the telephone, internet, or fax. Telemarketing may either be carried out by telemarketers or increasingly by automated telephone calls or "robocalls."


What Is Telemarketing?

Telemarketing is the direct marketing of goods or services to potential customers over the telephone, internet, or fax. Telemarketing may either be carried out by telemarketers or increasingly by automated telephone calls or "robocalls."

The intrusive nature of telemarketing, as well as reports of scams and fraud perpetrated over the telephone, has spurred a growing backlash against this direct marketing practice. Telemarketing may also be referred to as "telesales" or "inside sales."


* Telemarketing is the direct marketing of goods or services to potential customers over the telephone or the internet.
* Four common kinds of telemarketing include outbound calls, inbound calls, lead generation, and sales calls.
* Due to the intrusive nature of telemarketing, including spam calls, many customers are against it.
* Countries such as the U.S. and Canada have federal "Do Not Call" lists where individuals can register their phone numbers to avoid telemarketing calls.

How Telemarketing Works

Telemarketing is the practice of contacting, vetting, and approaching potential customers. It does not include the use of direct mail marketing methods.

Telemarketing may take place from a call center, an office, or, increasingly, a home. Many times, telemarketing can involve a single call to assess interest or suitability, and then follow-up calls to pursue a sale. Various data may be used to narrow down large databases of names to a small number of higher-probability customer prospects.

Telemarketing is used by for-profit businesses, nonprofit charities, political groups and candidates, surveying, donation solicitation, marketing research, and other kinds of organizations.

The term telemarketing was first used in the 1970s with the advent of a new, cheaper class of outbound long-distance telephone services and inbound toll-free services.

Types of Telemarketing Activities

The act of telemarketing can be divided into four subcategories:

* Outbound: Companies actively reach out to customer prospects and existing customers via outbound telemarketing calls, also known as "cold" calls.
* Inbound: These telemarketing calls are based on inbound inquiries about products or services as prompted by advertising or sales efforts. These are considered "warm" calls as customers will typically have submitted an interest form online or already be familiar with the company.
* Lead generation: This is the collection of intelligence about the profiles, interests, and demographic data of potential customers.
* Sales: Telemarketers who are trained salespeople engage in this persuasive activity. They aim to close a deal on the phone.

Telemarketing may entail a variety of activities, such as surveying, appointment-setting, telesales, database maintenance and cleaning, and providing a call to action.

Numerous North American companies outsource their telemarketing functions to lower-cost jurisdictions such as India, Mexico, and the Philippines.

Telemarketing: Criticism and Regulation

The intrusive nature of telemarketing, together with its association with scams and fraud, has turned a vast number of people against this direct marketing method. Often, telemarketing phone calls are unwelcome, and the companies that operate in this space are persistent.

Suspicious activity together with a backlash from the public has led many countries to lay down laws and police how telemarketers can operate.

Do Not Call (DNC) Registries

The United States and Canada have national "Do Not Call" (DNC) registries that give their residents a choice about whether to receive telemarketing calls at home. In the U.S., the registry is managed by the Federal Trade Commission (FTC) and enforced by the FTC, Federal Communications Commission, and state law enforcement officials.

Consumers who are registered in the DNC database can file a complaint if they receive a call from a telemarketer, which could lead to a stiff fine and sanctions for the telemarketing firm. However, calls from charities, political organizations, and telephone surveyors are permitted and therefore may be received by a consumer despite having their number listed on the DNC registry. Also permitted are calls from businesses with whom the consumer has an existing relationship, as well as those businesses where consent to call has been provided in writing.

Telemarketing Sales Rule in the U.S.

Other than giving people living in America the option to not be called by certain telemarketers, the FTC also:

* Has banned most forms of robocalling
* Requires telemarketers to make specific disclosures of material information
* Prohibits misrepresentations
* Sets limits on the times telemarketers can call consumers
* Prohibits calls to a consumer who has asked not to be called again
* Sets payment restrictions for the sale of certain goods and services

What Is an Example of Telemarketing?

If you receive a call from somebody you don’t know who seeks to sell you products or services, you are talking to a telemarketer. These individuals contact people usually with the intention of selling something and can be very persuasive.

Is Telemarketing an Easy Job?

Telemarketing isn’t for everyone. People working in this profession are generally hung up on continuously throughout the day. After being told where to shove it, you’ll be expected to quickly make another call without losing any enthusiasm. Not everyone is capable of dealing with such rejection or able to bounce back immediately. It takes a special kind of person to be able to deal with that and stay upbeat for eight-odd hours a day. You’ll also need to be really good at selling things.

Do Telemarketers Make Money?

Yes, though how much varies by company. Telemarketers are paid by the hour, by sale, or a combination of both. Commission is often a key component of salaries as it incentivizes staff to make sales. Usually, to earn a decent wage and avoid getting fired you’ll need to make your employer money.

The Bottom Line

It’s always wise to be extra diligent when you get a cold call about purchasing a good or service. Don't be pushed into doing anything you don’t feel comfortable with. Telemarketers can be very persuasive and talk us into doing something that maybe isn’t in our best interests.

Know your rights, don’t be afraid to ask questions, and take some time to make a decision if you need to. Most telemarketers are honest people but there are a few scammers out there, which is why we sadly always need to treat unknown callers with an element of suspicion.

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Additional Information

Telemarketing (sometimes known as inside sales, or telesales in the UK and Ireland) is a method of direct marketing in which a salesperson solicits prospective customers to buy products, subscriptions or services, either over the phone or through a subsequent face to face or web conferencing appointment scheduled during the call. Telemarketing can also include recorded sales pitches programmed to be played over the phone via automatic dialing.

Telemarketing is defined as contacting, qualifying, and canvassing prospective customers using telecommunications devices such as telephone, fax, and internet. It does not include direct mail marketing.


The term telemarketing was first used extensively in the late 1970s to describe Bell System communications which related to new uses for the outbound WATS and inbound Toll-free services.


The rise of telemarketing can be traced back to the 19th century telephonists, or switchboard operators. Trans-cultural hiring of switchboard operators (mostly women) became especially popular in North America throughout the 20th century, partially due to popularity gained through advertising.  After the shift from public switched telephone network to computer-based electronic switching system, the job of switchboard operators gradually diminished. However, with the rise of advertising and with the popularity of the telephone use, new jobs, including telemarketing jobs, were created.

Women in telemarketing

Telemarketing, as was the case with telephone operators, is one of the fields known to be occupied mostly by women. The central reason for hiring women operators lay in the fact that women's work was considered a form of cheap labor: female telemarketers earned about one-half to one-quarter of men's wages.  Women were also considered as more polite and well mannered than male operators.  Moreover, the calming, more delicate nature of a woman's voice was considered to be women's natural quality, although no scientific evidence supports this statement. This naturalization led to normalizing the perception of women as telephone operators and consultants, which is currently reflected in the telemarketing industry.


The two major categories of telemarketing are business-to-business and business-to-consumer.


* Lead generation, the gathering of information and contacts.
* Sales, using persuasion to sell a product or service.
* Outbound, proactive marketing in which prospective and preexisting customers are contacted directly,
* Inbound, reception of incoming orders and requests for information. Demand is generally created by advertising, publicity, or the efforts of outside salespeople.

Telemarketing office

Service Styles

* Call to Action, the implementation of outbound telemarketing to "activate" or elicit an action or response from prospects (i.e., entice prospects to visit a client's website).
* Appointment Setting, utilizing inbound or outbound telemarketing to create face-to-face or telephone appointments for sales purposes.
* Database Cleansing, the outbound calling of databases with the particular purpose to clean and prepare data (i.e. removing outdated and incorrect data) and contact details for future telemarketing campaigns.
* Surveys, the implementation of telemarketing (can be inbound or outbound) with the particular purpose of collecting data and information from specific target markets for qualitative research purposes.
* Telesales, telemarketing (inbound or outbound) with the specific intention of making an actual sale/transaction over the phone. Often includes the collection of credit card details over the phone for payment purposes, which allows for faster sales cycles and payment confirmation.


Telemarketing may be done from a company office, from a call center, or from home. It may involve a live operator voice broadcasting which is most frequently associated with political messages.

An effective telemarketing campaign often involves two or more calls. The first call (or series of calls) determines the customer's needs. The final call (or series of calls) motivates the customer to make a purchase. Prospective customers are identified by various means, including past purchase history, previous requests for information, credit limit, competition entry forms, and application forms. Names may also be purchased from another company's consumer database or obtained from a telephone directory or another public list. The qualification process is intended to determine which customers are most likely to purchase the product or service.

In business-to-business lead generation scenarios, telemarketing often targets perceived decision-makers who might be good prospects for a business product or service. The telemarketing approach is often combined with outreach via email or social media, typically referred to as a cadence. Calls are usually made by sales development representatives with the goal of this outreach being a subsequent meeting—often with an account executive at the vendor organization.

Charitable organizations, alumni associations, and political parties often use telemarketing to solicit donations. Marketing research companies use telemarketing techniques to survey the prospective or past customers of a client's business in order to assess market acceptance of or satisfaction with a particular product, service, brand, or company. Public opinion polls are conducted in a similar manner.

Telemarketing techniques are also applied to other forms of electronic marketing using e-mail or fax messages, in which case they are frequently considered spam by receivers.

Telemarketing agent sitting in a cubicle. The brightly colored rebuttal sheets are used to answer most questions a customer might have.

Negative perceptions and criticism

Telemarketing has been negatively associated with various scams and frauds, such as pyramid schemes, and with deceptively overpriced products and services. Fraudulent telemarketing companies are frequently referred to as "telemarketing boiler rooms" or simply "boiler rooms". Telemarketing is often criticized as an unethical business practice due to the perception of high-pressure sales techniques during unsolicited calls. Telemarketers marketing telephone companies may participate in telephone slamming, the practice of switching a customer's telephone service without their knowledge or authorization.

Telemarketing calls are often considered an annoyance, especially when they occur during the dinner hour, early in the morning, or late in the evening. Some companies have capitalized on these negative emotions. Since 2007 several forums have sprouted and act as complaint boards where consumers can voice their concerns and criticism. In response some telemarketing companies have filed lawsuits against these portals. The current legal system in the U.S grants such forums a certain degree of protection through "Communications Decency Act, 47 U.S.C 230" and California's Anti-SLAPP law.

Robotic telemarketing and ringless voicemail

A recent trend in telemarketing is to use robocalls: automated telephone calls that use both computerized autodialers and computer-delivered pre-recorded messages in a sales pitch. Some can simulate a personalized phone call through personalized pre-recorded messages.

Telemarketing has recently been advanced to implement a programmed women's voice as the operator instead of hiring a real woman to perform the task. This attempt has been shown to be unsuccessful. However, some scholars argue that such technological advancements reinforce commoditization of a woman's speech as a marketable entity and lead to "gendered hierarchy of communication".

Others tactics, such as ringless voicemail, can directly deliver a voice message directly to a landline's or cellphone's voicemail. Its original purpose was to provide a nonintrusive method of delivering valuable messages. There has been debate on ringless voicemail causing issues relating to "hijacking" of the voicemail by companies, which would disallow family and friends to access the voicemail.


In some countries telemarketing is subject to regulatory and legislative controls related to consumer privacy and protection.

United States

Telemarketing in the United States of America is restricted at the federal level by the Telephone Consumer Protection Act of 1991 (TCPA) (47 U.S.C. § 227) and the FTC's Telemarketing Sales Rule (TSR). The FCC derives regulatory authority from the TCPA, adopted as CFR 64.1200 and the Telemarketing and Consumer Fraud and Abuse Prevention Act, 15 U.S.C. 6101–6108. Many professional associations of telemarketers have codes of ethics and standards that member businesses follow to encourage public confidence.

Some jurisdictions have implemented "Do Not Call" lists through industry organizations or legislation; telemarketers are restricted from initiating contact with participating consumers. Legislative versions often provide for heavy penalties on companies which call individuals on these listings. The U.S. Federal Trade Commission has implemented a National Do Not Call Registry in an attempt to reduce intrusive telemarketing nationwide. Telemarketing corporations and trade groups challenged this as a violation of commercial speech rights. However, the U.S. 10th Circuit Court of Appeals upheld the National Do Not Call Registry on February 17, 2004.

Companies that use telemarketing as a sales tool are governed by the United States Federal regulations outlined in the TSR (amended on January 29, 2003 originally issued in 1995) and the TCPA. In addition to these Federal regulations, telemarketers calling nationally must also adhere to separate state regulations. Most states have adapted "do not call" files of their own, of which only some states share with the U.S. Federal Do Not Call registry. Each U.S. state also has its own regulations concerning: permission to record, permission to continue, no rebuttaling statutes, Sunday and Holiday calls; as well as the fines and punishments exacted for violations.

September 1, 2009, FTC regulations banning most robocalls went into effect.

Since many telemarketing calls now originate offshore, beyond the reach of US legal or regulatory agencies, the National Do Not Call Registry is usually ignored, as well as FTC regulations, and every possible number is called in an area code block. Some automated services are sophisticated enough to analyze the audio from the answering party, and if it determines that a human did not respond, will call repeatedly until one does or a limit is reached. This may be coupled with a fake Caller ID display ("spoofing") to mislead the call recipient into answering, or even thinking it is a local number calling. These are not actions of legitimate businesses.

Telemarketing techniques are increasingly used in political campaigns. Because of free-speech issues, the laws governing political phone calls are much less stringent than those applying to commercial messages. Even so, a number of states have barred or restricted political robocalls.

The National Do Not Call Registry has helped to substantially curb telemarketing calls to landlines and has also helped with the increasing trend for telemarketers to target mobile phones. As a result, there has been a greater push for mobile applications to help with unwanted calls from telemarketers, like PrivacyStar. These companies have helped to log thousands of complaints to the DNC Registry, since the inception of the registry itself.


Telemarketing in Canada is regulated by the Canadian Radio-television and Telecommunications Commission (CRTC), an agency of the federal department Innovation, Science and Economic Development Canada. Canadians can register with the National Do Not Call List (DNCL) to reduce the number of telemarketing calls received. Anyone who has received a telemarketing call which is in violation of one or more of the Unsolicited Telecommunications Rules may file a complaint to the national DNCL. The national DNCL operator then forwards all complaints to the CRTC, which determines whether a complaint warrants further investigation, based on their initial assessment.


Telemarketing in Australia is restricted by the Australian Federal Government and policed by the Australian Communications and Media Authority (ACMA). Australian Federal legislation provides for a restriction in calling hours for both Research and Marketing calls.

In 2007 a Do Not Call Register was established for Australian inbound telephone numbers. The register allows a user to register private use telephone numbers. Australian Federal Legislation limits the types of marketing calls that can be made to these registered telephone numbers; however, research calls are allowed. Other exemptions include calls made by charities and political members, parties and candidates however any organisation that is instructed by the recipient of a telemarketing call, not to call that number again, is legally obliged to comply, and must remove the phone number from the organisations calling list(s).

Inbound telemarketing is another major industry. It involves both live operators and IVR—Interactive Voice Response. IVR is also known as audio text or automated call processing. Usually, major television campaigns and advertisers use toll-free telephone number that are answered by IVR service bureaus. Such service bureaus have the technology and call capacity to process the large amounts of simultaneous calls that occur when a toll-free telephone number is advertised on television.


British police, after noting the high rate of pensioners affected, recommended use of do-not-call registry enrollment to enhance "phone security." Specific mention was also made of calls from "overseas companies."


Telemarketing restrictions in the UK are in place to protect consumers from unwanted and intrusive marketing calls. The use of predictive dialers, which are computer programs that dial telephone numbers automatically and connect the calls to an available agent, can make compliance with these restrictions more challenging. The Information Commissioner's Office (ICO), the UK's independent regulator for data protection and privacy, has issued guidelines on the use of predictive dialers for telemarketing, which require explicit consent from individuals, clear information about the purpose of the call and the business making the call, an option for individuals to opt-out of future calls, and an accurate and up-to-date call list. Additionally, businesses must ensure that their predictive dialer does not generate abandoned calls at a rate higher than 3% of live calls and must comply with the General Data Protection Regulation (GDPR) when processing personal data for marketing purposes. Failure to comply with these regulations can result in severe penalties, including fines and damage to a business's reputation.


In Finland, call centers employ an estimated 100,000 people, but most work with customer relations in larger companies. 10,000 people are working for companies involved with telemarketing. Telemarketing often is the first job young people get. But it is also a way out or back to the labour market for handicapped, immigrants and pensioners, In Finland, the profession has had a bad reputation because of work-related injuries. The strain on neck, shoulders, eyes and ears can be considerable. Health problems have however been reduced considerably thanks to lightweight headsets, ergonomic working stations and more tasks, like documentation, done automatically by computers.


The ability to cause a French phone number to appear on a Caller ID display, when the call originates outside of France was removed by a law passed in July 2018; implementation was delayed until August 1 of the following year.

* Technology
* Agent-assisted automation
* Autodialer
* Automatic call distributor
* Customer relationship management
* Predictive dialer
* Private Branch eXchange
* Teleblock
* Natural predictive dialing
* Ringless voicemail.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1888 2023-09-02 00:12:08

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1892) Accidents


An accident is an unpleasant event that happens unexpectedly and causes damage, injury or death.


An accident is an unintended, normally unwanted event that was not directly caused by humans. The term accident implies that nobody should be blamed, but the event may have been caused by unrecognized or unaddressed risks. Most researchers who study unintentional injury avoid using the term accident and focus on factors that increase risk of severe injury and that reduce injury incidence and severity. For example, when a tree falls down during a wind storm, its fall may not have been caused by humans, but the tree's type, size, health, location, or improper maintenance may have contributed to the result. Most car wrecks are not true accidents; however English speakers started using that word in the mid-20th century as a result of media manipulation by the US automobile industry.


Physical and non-physical

Physical examples of accidents include unintended motor vehicle collisions, tongue biting while eating, electric shock by accidentally touching bare electric wire, drowning, falls, being injured by touching something sharp or hot, or bumping into something while walking.

Non-physical examples are unintentionally revealing a secret or otherwise saying something incorrectly, accidental deletion of data, or forgetting an appointment.

Accidents by activity

Accidents during the execution of work or arising out of it are called work accidents. According to the International Labour Organization (ILO), more than 337 million accidents happen on the job each year, resulting, together with occupational diseases, in more than 2.3 million deaths annually.

In contrast, leisure-related accidents are mainly sports injuries.

Accidents by vehicle

Vehicle collisions are not usually accidents; they are mostly caused by preventable causes such as drunk driving and intentionally driving too fast. The use of the word accident to describe car wrecks was promoted by the US National Automobile Chamber of Commerce in the middle of the 20th century, as a way to make vehicle-related deaths and injuries seem like an unavoidable matter of fate, rather than a problem that could be addressed. The automobile industry accomplished this by writing customized articles as a free service for newspapers that used the industry's preferred language. Since 1994, the US National Highway Traffic Safety Administration has asked media and the public to not use the word accident to describe vehicle collisions.

* Aviation
* Bicycles
* Sailing ships
* Traffic collisions
* Train wrecks
* Trams

Domino effect accidents

In the process industry, a primary accident may propagate to nearby units, resulting in a chain of accidents, which is called domino effect accident.

Common causes

Incidence of accidents (of a severity of resulting in seeking medical care), sorted by activity (in Denmark in 2002)
Poisons, vehicle collisions and falls are the most common causes of fatal injuries. According to a 2005 survey of injuries sustained at home, which used data from the National Vital Statistics System of the United States National Center for Health Statistics, falls, poisoning, and fire/burn injuries are the most common causes of death.

The United States also collects statistically valid injury data (sampled from 100 hospitals) through the National Electronic Injury Surveillance System administered by the Consumer Product Safety Commission. This program was revised in 2000 to include all injuries rather than just injuries involving products. Data on emergency department visits is also collected through the National Health Interview Survey. In The U.S. the Bureau of Labor Statistics has available on their website extensive statistics on workplace accidents.


An accident is an unexpected event, typically sudden in nature and associated with injury, loss, or harm. Accidents are a common feature of the human experience and result in injury or permanent disability to large numbers of people worldwide every year. Many accidents also involve damage to or loss of property. Accidents can occur anywhere, including in the home, during transportation, in the hospital, on the sports field, or in the workplace. With appropriate safety precautions and awareness of one’s actions and environment, many accidents can be avoided or prevented.

Motor vehicle accidents

Worldwide, motor vehicle accidents are a major cause of death, and, despite improvements in automobile safety, projections have indicated that deaths from traffic crashes will increase significantly by 2030 because of increased motor vehicle ownership. Examples of causes of traffic accidents include speeding, drunk driving, distracted driving, and inexperienced driving. Although seat belts can save lives, millions of people fail to use them. Likewise, helmets are an effective means of protecting motorcyclists from traumatic brain injury and death, yet many riders choose not to wear a helmet.

Motor vehicle accidents result in a wide range of injuries and often in permanent disability. In an attempt to limit some of this damage, laws in places around the world have been enacted specifically to improve road safety. For example, some U.S. states have imposed universal helmet laws, requiring all motorcycle riders and passengers to wear protective helmets. Some governments impose fines on automobile drivers and passengers who do not use seat belts. Accidents involving buses are also responsible for injuries to large numbers of people, and this has led to mandatory seat belt use in some places. Safety features on cars, including seat belts, side-impact reinforcement, and air bags, have contributed to fewer injuries and deaths. Certain changes in the design of car bumpers and windshields have been aimed at causing less harm to pedestrians who may be hit. Preventive measures, such as campaigns on the dangers of drunk driving, enforcement of speed limits, the use of cameras to catch traffic law violators, and education of children about road safety, have helped raise public awareness about the importance of safety precautions on the road.

Sports accidents

Accidents during sports have long been the cause of debilitating injuries. Since the rise of modern organized sports in the 18th century, all sports—especially those involving contact, such as boxing, American football, and rugby—have witnessed crippling injuries, disability, and death. Sports in which an individual is elevated off the ground, such as horseback riding, mountain climbing, and rappelling, account for a high number of head and spinal injuries as well as fractures. From the latter part of the 20th century, the number of sports that deliberately court danger, the so-called extreme sports, grew rapidly and resulted in a concomitant number of injuries.

For some sports, changes in rules and safety equipment have helped to reduce the incidence and severity of accidents on the sports field. However, such action does not eradicate injury. For example, despite more stringent penalties for illegal checking in ice hockey and helmet-to-helmet contact in American football, concussion remains a major source of long-term disability in those sports.

Accidents in the home

The home is a site for many accidents. Stairways, bathrooms, and kitchens pose special hazards, as do utility closets, medicine cabinets, gardens, and swimming pools. Among children under age five, falls, burns, choking, poisoning, and drowning are common causes of injury or death at home. Falls are also common among older individuals.

A number of factors may precipitate accidents in the home. Poor supervision or poor housing conditions can increase the risk of accidents in the home for children. For example, unsupervised children may choke on small objects that have been within their reach. Likewise, poor electrical wiring and a lack of fire safety can result in significant injury and loss of property to fire.

Accidents in the hospital

Accidents involving procedures or medication can occur in hospitals and sometimes lead to permanent disability. For example, the use of instruments such as forceps can in rare instances result in brain trauma at birth. In some cases, medication errors may occur in which patients are given the wrong medication or too much or too little of a medication while in a hospital. Such errors can have severe adverse effects on patients. Hospitalized individuals also are susceptible to nosocomial, or health care-associated, infections, which in extreme cases can end in death.

Accidents in the workplace

Occupational hazards have always existed, but they became especially pronounced with the rise of modern factories, mines, and foundries in the 19th century. Industries such as construction and mining, in which heavy equipment is used, are associated with an elevated risk for severe injury. Constant and repetitive work can produce injuries such as prepatellar bursitis (or beat knee, caused by constant kneeling) and hand-arm vibration syndrome (or vibration white finger, caused by the handling of vibrating tools for long periods). Long-term exposure to materials such as asbestos can lead to chronic diseases such as mesothelioma. Occupations that involve sitting for long periods or typing constantly come with their own sets of risks. Carpal tunnel syndrome, for example, which can be caused by leaning the wrists on a desk while working at a computer, is one of the most-common repetitive stress injuries in the modern workplace.

Historically, there was little in the way of safety equipment to prevent accidents, and long-term exposure to dangerous chemicals could cause severe disablement and death. Before factory owners were called on to make their workplaces safer, many workers were injured in accidents. When permanent disability was the result, often that worker was doomed to a life of poverty, since there was often little in the way of compensation for his or her injury. The rise of occupational medicine in the industrial era, accompanied by an increased recognition of occupational hazards, led to improved measures of protection for workers.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1889 2023-09-03 00:33:56

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1893) Surgeon


A surgeon is a doctor who specializes in evaluating and treating conditions that may require surgery, or physically changing the human body. Surgeries can be done to diagnose or treat disease or injury. In the operating room, surgeons lead a team of other doctors and nurses to make sure that a procedure goes smoothly.


In modern medicine, a surgeon is a medical doctor who performs surgery. Although there are different traditions in different times and places, a modern surgeon is also a licensed physician or received the same medical training as physicians before specializing in surgery. There are also surgeons in podiatry, dentistry, and veterinary medicine. It is estimated that surgeons perform over 300 million surgical procedures globally each year.


The first person to document a surgery was the 6th century BC Indian physician-surgeon, Sushruta. He specialized in cosmetic plastic surgery and even documented an open rhinoplasty procedure. His magnum opus Suśruta-saṃhitā is one of the most important surviving ancient treatises on medicine and is considered a foundational text of both Ayurveda and surgery. The treatise addresses all aspects of general medicine, but the translator G. D. Singhal dubbed Sushruta "the father of surgical intervention" on account of the extraordinarily accurate and detailed accounts of surgery to be found in the work.

After the eventual decline of the Sushruta School of Medicine in India, surgery was largely ignored until the Islamic Golden Age surgeon Al-Zahrawi (936–1013) re-established surgery as an effective medical practice. He is considered the greatest medieval surgeon to have appeared from the Islamic World, and has also been described as the father of surgery. His greatest contribution to medicine is the Kitab al-Tasrif, a thirty-volume encyclopedia of medical practices. He was the first physician to describe an ectopic pregnancy, and the first physician to identify the hereditary nature of haemophilia.

His pioneering contributions to the field of surgical procedures and instruments had an enormous impact on surgery but it was not until the 18th century that surgery emerged as a distinct medical discipline in England.

In Europe, surgery was mostly associated with barber-surgeons who also used their hair-cutting tools to undertake surgical procedures, often at the battlefield and also for their employers. With advances in medicine and physiology, the professions of barbers and surgeons diverged; by the 19th century barber-surgeons had virtually disappeared, and surgeons were almost invariably qualified doctors who had specialized in surgery. Surgeon continued, however, to be used as the title for military medical officers until the end of the 19th century, and the title of Surgeon General continues to exist for both senior military medical officers and senior government public health officers.

Titles in the Commonwealth

In 1950, the Royal College of Surgeons of England (RCS) in London began to offer surgeons a formal status via RCS membership. The title Mister became a badge of honour, and today, in many Commonwealth countries, a qualified doctor who, after at least four years' training, obtains a surgical qualification (formerly Fellow of the Royal College of Surgeons, but now also Member of the Royal College of Surgeons or a number of other diplomas) is given the honour of being allowed to revert to calling themselves Mr, Miss, Mrs or Ms in the course of their professional practice, but this time the meaning is different. It is sometimes assumed that the change of title implies consultant status (and some mistakenly think non-surgical consultants are Mr too), but the length of postgraduate medical training outside North America is such that a qualified surgeon may be years away from obtaining such a post: many doctors previously obtained these qualifications in the senior house officer grade, and remained in that grade when they began sub-specialty training. The distinction of Mr (etc.) is also used by surgeons in the Republic of Ireland, some states of Australia, Barbados, New Zealand, South Africa, Zimbabwe, and some other Commonwealth countries. In August 2021, the Royal Australasian College of Surgeons announced that it was advocating for this practice to be phased out and began encouraging the use of the gender neutral title Dr or appropriate academic titles such as Professor.

Military titles

In many English-speaking countries the military title of surgeon is applied to any medical practitioner, due to the historical evolution of the term. The US Army Medical Corps retains various surgeon United States military occupation codes in the ranks of officer pay grades, for military personnel dedicated to performing surgery on wounded soldiers.


* Cardiac surgery (in the United States considered part of cardiothoracic surgery)
* Colon and rectal surgery
* Craniofacial surgery
* Dental surgery
* Endocrine surgery
* General surgery
* Neurological surgery
* Obstetrics and gynaecology
* Ophthalmology
* Oral and maxillofacial surgery
* Orthopedic surgery
* Otorhinolaryngology
* Pediatric surgery
* Plastic surgery
* Podiatric surgery
* Surgical oncology
* Thoracic surgery (in the United States considered part of cardiothoracic surgery)
* Transplant surgery
* Trauma surgery
* Upper gastrointestinal surgery
* Urology
* Vascular surgery

Some physicians who are general practitioners or specialists in family medicine or emergency medicine may perform limited ranges of minor, common, or emergency surgery. Anesthesia often accompanies surgery, and anesthesiologists and nurse anesthetists may oversee this aspect of surgery. Surgeon's assistant, surgical nurses, surgical technologists are trained professionals who support surgeons.

In the United States, the Department of Labor description of a surgeon is "a physician who treats diseases, injuries, and deformities by invasive, minimally-invasive, or non-invasive surgical methods, such as using instruments, appliances, or by manual manipulation".


Surgeons use instruments to change or move live tissue, including:

* Lasers
* Ultrasound
* Ionizing
* Radiation
* Scalpels
* Probes
* Needles

What Does a Surgeon Do?

There are two main types of surgery. Open surgery requires a cut into the skin so the surgeon can see into the body. Minimally invasive surgery requires smaller entry points to make repairs and take tissue samples. It generally has less recovery time than open surgery. But not all surgeries have a minimally-invasive option.

There are different surgeons for each area of your body, and each uses a variety of techniques. Some of the most common surgery specialties are:

* General surgeon. A general surgeon operates on a wide range of conditions that can affect almost any part of your body.
* Colon and rectal surgeon. Patients with issues in any part of their intestines will probably see this specialist.
* Neurosurgeon. Neurosurgeons deal with disorders and illnesses related to your brain and nervous system.
* Obstetrician and gynecologist (OB/GYN). OB/GYNs have two areas of expertise. The first involves working with pregnant women, delivering babies, and caring for babies after they're born. The second is treating conditions related to the female reproductive system.
* Ophthalmologist. One of the duties of this kind of eye doctor is doing surgical procedures to correct eye and visual problems. 
* Oral and maxillofacial surgeon. This surgeon operates on the head, neck, face, and jaw.
* Orthopedic surgeon. Orthopedic surgeons treat issues of the musculoskeletal system, which includes bones, muscles, joints, arteries, associated nerves, and overlying skin.
* Otolaryngologist. Otolaryngologists are also called ear, nose, and throat (ENT) doctors because they specialize in those three body parts.
* Pediatric surgeon. Pediatric surgeons work with children, from newborns to teenagers.
* Plastic and maxillofacial surgeon. Plastic surgeons do cosmetic surgeries as well as handle the repair, replacement, and reconstruction of the body.
* Thoracic surgeon. Also called cardiac or cardiothoracic surgeons, these doctors specialize in operating on your heart and other chest organs.
* Urologist. An urologist typically operates on your kidneys, ureters, bladder, prostate, urethra, and testes.
* Vascular surgeon. Vascular surgeons operate on your circulatory system.

Education and Training

The path to becoming a surgeon is long and intense. It involves:

* College. The first step is to earn an undergraduate degree, typically in pre-med or another science-oriented subject.
* Medical College Admission Test (MCAT). Those who hope to be surgeons must pass this exam. Many students take it during their final years of college so they have plenty of time to apply for medical school before graduating.
* Medical school. The next step is 4 years of medical school. Many medical schools offer specific tracks of study.
Surgical specialty and residency. Around graduation, doctors need to decide which specialty area they want to pursue and find a residency program. Some specialties may require additional exams.
* Surgical residencies last at least 5 years, longer than other areas of medicine. After residency, doctors may begin working as surgeons.

Reasons to See a Surgeon

Surgery can be emergent or elective. Emergent surgeries are done for an urgent life-threatening condition, such as a serious injury. Elective surgeries can be scheduled in advance and don't need to be performed right away, although they aren’t always optional.

You may have surgery to:

* Learn more about a condition to get an accurate diagnosis
* Get a tissue sample from a suspicious area
* Repair or remove diseased tissue or organs
* Take out an obstruction
* Move body parts back to their correct position
* Redirect blood vessels
* Transplant organs
* Put mechanical or electronic devices inside the body
* Change your appearance

Additional Information

Surgery is branch of medicine that is concerned with the treatment of injuries, diseases, and other disorders by manual and instrumental means. Surgery involves the management of acute injuries and illnesses as differentiated from chronic, slowly progressing diseases, except when patients with the latter type of disease must be operated upon.

A general treatment of surgery follows.


Surgery is as old as humanity, for anyone who has ever stanched a wound has acted as a surgeon. In some ancient civilizations surgery reached a rather high level of development, as in India, China, Egypt, and Hellenistic Greece. In Europe during the Middle Ages, the practice of surgery was not taught in most universities, and ignorant barbers instead wielded the knife, either on their own responsibility or upon being called into cases by physicians. The organization of the United Company of Barber Surgeons of London in 1540 marked the beginning of some control of the qualifications of those who performed operations. This guild was the precursor of the Royal College of Surgeons of England.

In the 18th century, with increasing knowledge of anatomy, such operative procedures as amputations of the extremities, excision of tumours on the surface of the body, and removal of stones from the urinary bladder had helped to firmly establish surgery in the medical curriculum. Accurate anatomical knowledge enabled surgeons to operate more rapidly; patients were sedated with opium or made drunk with alcohol, tied down, and a leg amputation, for example, could then be done in three to five minutes. The pain involved in such procedures, however, continued to limit expansion of the field until the introduction of ether anesthesia in 1846. The number of operations thereafter increased markedly, but only to accentuate the frequency and severity of “surgical infections.”

In the mid-19th century the French microbiologist Louis Pasteur developed an understanding of the relationship of bacteria to infectious diseases, and the application of this theory to wound sepsis by the British surgeon Joseph Lister from 1867 resulted in the technique of antisepsis, which brought about a remarkable reduction in the mortality rate from wound infections after operations. The twin emergence of anesthesia and antisepsis marked the beginning of modern surgery.

Wilhelm Conrad Röntgen’s discovery of X-rays at the turn of the 20th century added an important diagnostic tool to surgery, and the discovery of blood types in 1901 by Austrian biologist Karl Landsteiner made transfusions safer. New techniques of anesthesia involving not only new agents for inhalation but also regional anesthesia accomplished by nerve blocking (spinal and local anesthesia) were also introduced. The use of positive pressure and controlled respiration techniques (to prevent the lung from collapsing when the pleural cavity was opened) made chest surgery practical and relatively safe for the first time. The intravenous administration (injection into the veins) of anesthetic agents was also adopted. In the period from the 1930s to the 1960s, the replenishment of body fluids by intravenous infusion, the introduction of chemicals and antibiotics to fight infection and to treat the metabolically disturbed body, and the development of heart-lung machines helped bring surgery to a state in which every body cavity, system, organ, and area could safely be operated on.

Present-day surgery

Contemporary surgical therapy is greatly helped by monitoring devices that are used during surgery and during the postoperative period. Blood pressure and pulse rate are monitored during an operation because a fall in the former and a rise in the latter give evidence of a critical loss of blood. Other items monitored are the heart contractions as indicated by electrocardiograms; tracings of brain waves recorded by electroencephalograms, which reflect changes in brain function; the oxygen level in arteries and veins; carbon dioxide partial pressure in the circulating blood; and respiratory volume and exchange. Intensive monitoring of the patient usually continues into the critical postoperative stage.

Asepsis, the freedom from contamination by pathogenic organisms, requires that all instruments and dry goods coming in contact with the surgical field be sterilized. This is accomplished by placing the materials in an autoclave, which subjects its contents to a period of steam under pressure. Chemical sterilization of some instruments is also used. The patient’s skin is sterilized by chemicals, and members of the surgical team scrub their hands and forearms with antiseptic or disinfectant soaps. Sterilized gowns, caps, and masks that filter the team’s exhaled air and sterilized gloves of disposable plastic complete the picture. Thereafter, attention to avoiding contact with nonsterilized objects is the basis of maintaining asepsis.

During an operation, hemostasis (the arresting of bleeding) is achieved by use of the hemostat, a clamp with ratchets that grasps blood vessels or tissue; after application of hemostats, suture materials are tied around the bleeding vessels. Absorbent sterile napkins called sponges, made of a variety of natural and synthetic materials, are used for drying the field. Bleeding may also be controlled by electrocautery, the use of an instrument heated with an electric current to cauterize, or burn, vessel tissue. The most commonly used instruments in surgery are still the scalpel (knife), hemostatic forceps, flexible tissue-holding forceps, wound retractors for exposure, crushing and noncrushing clamps for intestinal and vascular surgery, and the curved needle for working in depth.

The most common method of closing wounds is by sutures. There are two basic types of suture materials; absorbable ones such as catgut (which comes from sheep intestine) or synthetic substitutes; and nonabsorbable materials, such as nylon sutures, steel staples, or adhesive tissue tape. Catgut is still used extensively to tie off small blood vessels that are bleeding, and since the body absorbs it over time, no foreign materials are left in the wound to become a focus for disease organisms. Nylon stitches and steel staples are removed when sufficient healing has taken place.

There are three general techniques of wound treatment; primary intention, in which all tissues, including the skin, are closed with suture material after completion of the operation; secondary intention, in which the wound is left open and closes naturally; and third intention, in which the wound is left open for a number of days and then closed if it is found to be clean. The third technique is used in badly contaminated wounds to allow drainage and thus avoid the entrapment of microorganisms. Military surgeons use this technique on wounds contaminated by shell fragments, pieces of clothing, and dirt.

The 20th and 21st centuries witnessed several new surgical technologies to supplement the techniques of manual incision. Lasers became widely used to destroy tumours and other pigmented lesions, some of which are inaccessible by conventional surgery. They are also used to surgically weld detached retinas back in place and to coagulate blood vessels to stop them from bleeding. Stereotaxic surgery uses a three-dimensional system of coordinates obtained by X-ray photography to accurately focus high-intensity radiation, cold, heat, or chemicals on tumours located deep in the brain that could not otherwise be reached. Cryosurgery uses extreme cold to destroy warts and precancerous and cancerous skin lesions and to remove cataracts. Some traditional techniques of open surgery were replaced by the use of a thin flexible fibre-optic tube equipped with a light and a video connection; the tube, or endoscope, is inserted into various bodily passages and provides views of the interior of hollow organs or vessels. Accessories added to the endoscope allow small surgical procedures to be executed inside the body without making a major incision.

Preoperative and postoperative care both have the same object: to restore patients to as near their normal physiologic state as possible. Blood transfusions, intravenous administration of fluids, and the use of measures to prevent common complications such as lung infection and blood clotting in the legs are the principal features of postoperative care.

There are four major categories of surgery: (1) wound treatment, (2) extirpative surgery, (3) reconstructive surgery, and (4) transplantation surgery. The technical aspects of wound surgery, already partly discussed, centre on procuring good healing and the avoidance of infection. Extirpative surgery involves the removal of diseased tissue or organs. Cancer surgery usually falls into this category, with mastectomy (removal of the breast), cholecystectomy (removal of the gallbladder), and hysterectomy (removal of the uterus) among the most frequent procedures. Reconstructive surgery deals with the replacement of lost tissues, whether from fractures, burns, or degenerative-disease processes, and is especially prominent in the practice of plastic surgery and orthopedic surgery. Grafts from the patient or from others are frequently used to replace lost tissues. Reconstructive surgery also uses artificial devices (prostheses) to replace damaged or diseased organs or tissues. Common examples are the use of metal in reconstructing hip joints and the use of plastic valves to replace heart valves. Transplantation surgery involves the use of organs transplanted from other bodies to replace diseased organs in patients. Kidneys are the most commonly transplanted organs.

The major medical specialties involving surgery are general surgery, plastic surgery, orthopedic surgery, obstetrics and gynecology, neurosurgery, thoracic surgery, colon and rectal surgery, otolaryngology, ophthalmology, and urology. General surgery is the parent specialty and now centres on operations involving the stomach, intestines, breast, blood vessels in the extremities, endocrine glands, tumours of soft tissues, and amputations. Plastic surgery is concerned with the bodily surface and with reconstructive work of the face and exposed parts. Orthopedic surgery deals with the bones, tendons, ligaments, and muscles; fractures of the extremities and congenital skeletal defects are common targets of treatment. Obstetricians perform cesarean sections, while gynecologists operate to remove tumours from the uterus and ovaries. Neurosurgeons operate to remove brain tumours, treat injuries to the brain resulting from skull fractures, and treat ruptured intravertebral disks that affect the spinal cord. Thoracic surgeons treat disorders of the lungs; the subspecialty of cardiovascular surgery is concerned with the heart and its major blood vessels and has become a major field of surgical endeavour. Colon and rectal surgery deals with disorders of the large intestine. Otolaryngologic surgery is performed in the area of the ear, nose, and throat (e.g., tonsillectomy), while ophthalmologic surgery deals with disorders of the eyes. Urologic surgery treats diseases of the urinary tract and, in males, of the genital apparatus.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1890 2023-09-04 00:42:02

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1894) Stock Market


A stock market, equity market, or share market is the aggregation of buyers and sellers of stocks (also called shares), which represent ownership claims on businesses; these may include securities listed on a public stock exchange, as well as stock that is only traded privately, such as shares of private companies which are sold to investors through equity crowdfunding platforms. Investment is usually made with an investment strategy in mind.

Size of the market

The total market capitalization of all publicly traded securities worldwide rose from US$2.5 trillion in 1980 to US$93.7 trillion at the end of 2020.

As of 2016, there are 60 stock exchanges in the world. Of these, there are 16 exchanges with a market capitalization of $1 trillion or more, and they account for 87% of global market capitalization. Apart from the Australian Securities Exchange, these 16 exchanges are all in North America, Europe, or Asia.

By country, the largest stock markets as of January 2022 are in the United States of America (about 59.9%), followed by Japan (about 6.2%) and United Kingdom (about 3.9%).

Stock exchange

A stock exchange is an exchange (or bourse) where stockbrokers and traders can buy and sell shares (equity stock), bonds, and other securities. Many large companies have their stocks listed on a stock exchange. This makes the stock more liquid and thus more attractive to many investors. The exchange may also act as a guarantor of settlement. These and other stocks may also be traded "over the counter" (OTC), that is, through a dealer. Some large companies will have their stock listed on more than one exchange in different countries, so as to attract international investors.

Stock exchanges may also cover other types of securities, such as fixed-interest securities (bonds) or (less frequently) derivatives, which are more likely to be traded OTC.

Trade in stock markets means the transfer (in exchange for money) of a stock or security from a seller to a buyer. This requires these two parties to agree on a price. Equities (stocks or shares) confer an ownership interest in a particular company.

Participants in the stock market range from small individual stock investors to larger investors, who can be based anywhere in the world, and may include banks, insurance companies, pension funds and hedge funds. Their buy or sell orders may be executed on their behalf by a stock exchange trader.

Some exchanges are physical locations where transactions are carried out on a trading floor, by a method known as open outcry. This method is used in some stock exchanges and commodities exchanges, and involves traders shouting bid and offer prices. The other type of stock exchange has a network of computers where trades are made electronically. An example of such an exchange is the NASDAQ.

A potential buyer bids a specific price for a stock, and a potential seller asks a specific price for the same stock. Buying or selling at the Market means you will accept any ask price or bid price for the stock. When the bid and ask prices match, a sale takes place, on a first-come, first-served basis if there are multiple bidders at a given price.

The purpose of a stock exchange is to facilitate the exchange of securities between buyers and sellers, thus providing a marketplace. The exchanges provide real-time trading information on the listed securities, facilitating price discovery.

The New York Stock Exchange (NYSE) is a physical exchange, with a hybrid market for placing orders electronically from any location as well as on the trading floor. Orders executed on the trading floor enter by way of exchange members and flow down to a floor broker, who submits the order electronically to the floor trading post for the Designated market maker ("DMM") for that stock to trade the order. The DMM's job is to maintain a two-sided market, making orders to buy and sell the security when there are no other buyers or sellers. If a bid–ask spread exists, no trade immediately takes place – in this case, the DMM may use their own resources (money or stock) to close the difference. Once a trade has been made, the details are reported on the "tape" and sent back to the brokerage firm, which then notifies the investor who placed the order. Computers play an important role, especially for program trading.

The NASDAQ is an electronic exchange, where all of the trading is done over a computer network. The process is similar to the New York Stock Exchange. One or more NASDAQ market makers will always provide a bid and ask the price at which they will always purchase or sell 'their' stock.

The Paris Bourse, now part of Euronext, is an order-driven, electronic stock exchange. It was automated in the late 1980s. Prior to the 1980s, it consisted of an open outcry exchange. Stockbrokers met on the trading floor of the Palais Brongniart. In 1986, the CATS trading system was introduced, and the order matching system was fully automated.

People trading stock will prefer to trade on the most popular exchange since this gives the largest number of potential counter parties (buyers for a seller, sellers for a buyer) and probably the best price. However, there have always been alternatives such as brokers trying to bring parties together to trade outside the exchange. Some third markets that were popular are Instinet, and later Island and Archipelago (the latter two have since been acquired by Nasdaq and NYSE, respectively). One advantage is that this avoids the commissions of the exchange. However, it also has problems such as adverse selection. Financial regulators have probed dark pools.

Market participant

Market participants include individual retail investors, institutional investors (e.g., pension funds, insurance companies, mutual funds, index funds, exchange-traded funds, hedge funds, investor groups, banks and various other financial institutions), and also publicly traded corporations trading in their own shares. Robo-advisors, which automate investment for individuals are also major participants.

Demographics of market participation:

Indirect vs. Direct Investment

Indirect investment involves owning shares indirectly, such as via a mutual fund or an exchange traded fund. Direct investment involves direct ownership of shares.

Direct ownership of stock by individuals rose slightly from 17.8% in 1992 to 17.9% in 2007, with the median value of these holdings rising from $14,778 to $17,000. Indirect participation in the form of retirement accounts rose from 39.3% in 1992 to 52.6% in 2007, with the median value of these accounts more than doubling from $22,000 to $45,000 in that time. Rydqvist, Spizman, and Strebulaev attribute the differential growth in direct and indirect holdings to differences in the way each are taxed in the United States. Investments in pension funds and 401ks, the two most common vehicles of indirect participation, are taxed only when funds are withdrawn from the accounts. Conversely, the money used to directly purchase stock is subject to taxation as are any dividends or capital gains they generate for the holder. In this way, the current tax code incentivizes individuals to invest indirectly.

Participation by income and wealth strata

Rates of participation and the value of holdings differ significantly across strata of income. In the bottom quintile of income, 5.5% of households directly own stock and 10.7% hold stocks indirectly in the form of retirement accounts. The top decile of income has a direct participation rate of 47.5% and an indirect participation rate in the form of retirement accounts of 89.6%. The median value of directly owned stock in the bottom quintile of income is $4,000 and is $78,600 in the top decile of income as of 2007. The median value of indirectly held stock in the form of retirement accounts for the same two groups in the same year is $6,300 and $214,800 respectively. Since the Great Recession of 2008 households in the bottom half of the income distribution have lessened their participation rate both directly and indirectly from 53.2% in 2007 to 48.8% in 2013, while over the same period households in the top decile of the income distribution slightly increased participation 91.7% to 92.1%. The mean value of direct and indirect holdings at the bottom half of the income distribution moved slightly downward from $53,800 in 2007 to $53,600 in 2013. In the top decile, mean value of all holdings fell from $982,000 to $969,300 in the same time. The mean value of all stock holdings across the entire income distribution is valued at $269,900 as of 2013.

Participation by race and gender

The racial composition of stock market ownership shows households headed by whites are nearly four and six times as likely to directly own stocks than households headed by blacks and Hispanics respectively. As of 2011 the national rate of direct participation was 19.6%, for white households the participation rate was 24.5%, for black households it was 6.4% and for Hispanic households it was 4.3%. Indirect participation in the form of 401k ownership shows a similar pattern with a national participation rate of 42.1%, a rate of 46.4% for white households, 31.7% for black households, and 25.8% for Hispanic households. Households headed by married couples participated at rates above the national averages with 25.6% participating directly and 53.4% participating indirectly through a retirement account. 14.7% of households headed by men participated in the market directly and 33.4% owned stock through a retirement account. 12.6% of female-headed households directly owned stock and 28.7% owned stock indirectly.

Determinants and possible explanations of stock market participation

In a 2003 paper by Vissing-Jørgensen attempts to explain disproportionate rates of participation along wealth and income groups as a function of fixed costs associated with investing. Her research concludes that a fixed cost of $200 per year is sufficient to explain why nearly half of all U.S. households do not participate in the market. Participation rates have been shown to strongly correlate with education levels, promoting the hypothesis that information and transaction costs of market participation are better absorbed by more educated households. Behavioral economists Harrison Hong, Jeffrey Kubik and Jeremy Stein suggest that sociability and participation rates of communities have a statistically significant impact on an individual's decision to participate in the market. Their research indicates that social individuals living in states with higher than average participation rates are 5% more likely to participate than individuals that do not share those characteristics. This phenomenon also explained in cost terms. Knowledge of market functioning diffuses through communities and consequently lowers transaction costs associated with investing.

(The Nasdaq Stock Market (National Association of Securities Dealers Automated Quotations Stock Market) is an American stock exchange based in New York City. It is the most active stock trading venue in the US by volume, and ranked second on the list of stock exchanges by market capitalization of shares traded, behind the New York Stock Exchange. The exchange platform is owned by Nasdaq, Inc., which also owns the Nasdaq Nordic stock market network and several U.S.-based stock and options exchanges.)

Additional Information:

What Are Stock Exchanges?

A stock exchange does not own shares. Instead, it acts as a market where stock buyers connect with stock sellers. Stocks can be traded on several exchanges such as the New York Stock Exchange (NYSE) or the Nasdaq.

Although most stocks are traded through a broker, it is important to understand the relationship between exchanges and the companies that trade. Also, there are various requirements for different exchanges designed to protect investors.


A stock exchange is a centralized location that brings corporations and governments so that investors can buy and sell equities.

Auction-based exchanges such as the New York Stock Exchange allow traders and brokers to physically and verbally communicate buy and sell orders.

Electronic exchanges take place on electronic platforms, so they don't require a centralized physical location for trades.
Electronic communication networks connect buyers and sellers directly by bypassing market makers.

The OTCBB has been closed by FINRA.

How Stock Exchanges Work

A stock exchange is where different financial instruments are traded, including equities, commodities, and bonds. Exchanges bring corporations and governments, together with investors. Exchanges help provide liquidity in the market, meaning there are enough buyers and sellers so that trades can be processed efficiently without delays.

Exchanges also ensure that trading occurs in an orderly and fair manner so important financial information can be transmitted to investors and financial professionals.

Stocks first become available on an exchange after a company conducts its initial public offering (IPO). A company sells shares to an initial set of public shareholders in an IPO known as the primary market. After the IPO floats shares into the hands of public shareholders, these shares can be sold and purchased on an exchange or the secondary market.

The general public can trade shares on the secondary market after a company's initial public offering.

The exchange tracks the flow of orders for each stock, and it's the flow of supply and demand that establishes a stock's price. Depending on the type of brokerage account, you may be able to view this flow of price action. For example, if a stock's bid price is $40, this means an investor is telling the exchange that they are willing to buy the stock for $40. At the same time, you may see an asking price of $41, meaning somebody else is willing to sell the stock for $41. The difference between the two is the bid-ask spread.

Auction Exchanges

Auction exchanges—or the auction market—is a place where buyers and sellers put in competitive bids and offers simultaneously. In an auction exchange, the current stock price is the highest price a buyer is willing to spend on a security, while the lowest price is what the seller will accept. Trades are then matched, and when paired together, the order is executed.

The auction market is also referred to as the open outcry system. Brokers and traders communicate physically and verbally on the trading floor or pit to buy and sell securities. Although this system is slowly being phased out by electronic systems, some exchanges still use the auction system, including the New York Stock Exchange  (NYSE).

The NYSE Closing Auction is the last event of the trading day when the closing price for each stock is determined by bringing all buyers and sellers together to establish a price for all those involved.

The NYSE closing auction is one of the busiest trading times in the U.S. equity markets when nearly 223 million shares are traded.

New York Stock Exchange (NYSE)

The New York Stock Exchange is the world's largest equities exchange.

The parent company of the New York Stock Exchange is Intercontinental Exchange (ICE) as a result of the merger with the European exchange Euronext in 2007.

Although some of its functions have been transferred to electronic trading platforms, it remains one of the world's leading auction markets, meaning specialists (called "Designated Market Makers") are physically present on its trading floors.

Each specialist specializes in a particular stock, buying and selling the stock in the auction.

These professionals are under competitive threat by electronic-only exchanges that claim to be more efficient—that is, they execute faster trades and exhibit smaller bid-ask spreads—by eliminating human intermediaries.

Companies listed on the NYSE have great credibility because they have to meet initial listing requirements and comply with annual maintenance requirements. To keep trading on the exchange, companies must keep their price above $4 per share.

Investors who trade on the NYSE benefit from a set of minimum protections. Among several of the requirements that the NYSE has enacted, the following two are especially significant:

Equity incentive plans must receive shareholder approval.

A majority of the board of directors' members must be independent, the compensation committee must be entirely composed of independent directors, and the audit committee must include at least one person who possesses "accounting or related financial management expertise."

Electronic Exchanges

Many exchanges now allow trading electronically. There are no traders and no physical trading activity. Instead, trading takes place on an electronic platform and doesn't require a centralized location where buyers and sellers can meet.

These exchanges are considered more efficient and much faster than traditional exchanges and carry out billions of dollars in trades each day. The Nasdaq is one of the world's leading electronic exchanges.

The Nasdaq

The Nasdaq is sometimes called screen-based because buyers and sellers are only connected by computers over a telecommunications network. Market makers, also known as dealers, carry their own inventory of stock. They stand ready to buy and sell stocks on the Nasdaq and are required to post their bid and ask prices.

The exchange has listing and governance requirements similar to the NYSE. For example, a stock must maintain a $4 minimum price. If a company does not maintain these requirements, it can be delisted to an over-the-counter (OTC) market.

For example, on the New York Stock Exchange (NYSE), if a security's price closed below $1.00 for 30 consecutive trading days, that exchange would initiate the delisting process.

On average, more than 5 million trades are executed via the Nasdaq on a daily basis.

Electronic Communication Networks (ECNs)

Electronic communication networks (ECNs) are part of an exchange class called alternative trading systems (ATSs). ECNs connect buyers and sellers directly because they allow a direct connection between the two; ECNs bypass market makers.

Think of them as an alternative means to trade stocks listed on the Nasdaq and, increasingly, other exchanges such as the NYSE or foreign exchanges.

There are several innovative and entrepreneurial ECNs that are generally good for customers because they pose a competitive threat to traditional exchanges, and therefore push down transaction costs. Although some ECNs allow retail investors to trade, ECNs are mostly used by institutional investors, which are firms that invest large sums for other investors, such as pension fund managers.

Examples of ECNs include Nasdaq's Interbank Network Electronic Transfer (INET) and Arca Options, which are overseen by the NYSE.

Electronic communication networks (ECN) enable brokerage firms and traders from various geographical regions of the world to trade outside the normal trading hours of major exchanges.

Over-the-Counter (OTC)

The term over-the-counter (OTC) refers to markets other than the organized exchanges described above. OTC markets generally list small companies, many of which have fallen off to the OTC market because they were delisted. Two of the major OTC markets include:

Over-the-Counter Bulletin Board (OTCBB)

The Over-the-Counter Bulletin Board (OTCBB) was an electronic community of market makers. Companies that fall off the Nasdaq often ended up here. Once on the OTCBB, there were no quantitative minimums or no minimum annual sales or assets required to list.

The OTC Bulletin Board was closed in November 2021.

Pink Sheets

The second OTC market is referred to as the Pink Sheets, a listing service that doesn't require companies to register with the Securities and Exchange Commission (SEC). Liquidity is often minimal, and these companies are not required to submit quarterly 10Qs.

OTC Risks

Some individual investors are wary of OTC stocks because of the extra risks involved. On the other hand, some strong companies trade on the OTC. In fact, several larger companies have deliberately switched to OTC markets to avoid the administrative burden and costly fees that accompany regulatory oversight laws such as the Sarbanes-Oxley Act.

You should also be careful when investing in the OTC if you do not have experience with penny stocks, as these primarily trade over-the-counter.

Other Exchanges

There are many other exchanges located throughout the world, including exchanges that trade stocks and bonds as well as those that exchange digital currencies.


The TSE has more than 3,800 listed companies, with a combined market capitalization of more than $5.6 trillion.

The Shanghai Stock Exchange (SSE) is the largest in mainland China. Many investments are traded on the exchange, including stocks, bonds, and mutual funds. The Shenzhen Stock Exchange (SZSE) is the second-largest stock exchange operating independently in China.


Euronext is Europe's largest stock exchange, and although it has undergone multiple mergers, it was initially formed by the mergers of the Amsterdam, Paris, and Brussels stock exchanges. The London Stock Exchange (LSE) is located in the United Kingdom and is the second-largest exchange in Europe.

The most popular index within the LSE is the Financial Times Stock Exchange (FTSE) 100 Share Index. The “Footsie” contains the top 100 well-established publicly traded companies or blue-chip stocks.

Digital Exchanges

Coinbase is the leading cryptocurrency exchange in the United States. Coinbase has an advanced trading platform that facilitates cryptocurrency trades for retail investors and custodial accounts for institutions. Although Bitcoin is the most popular cryptocurrency, others are traded via Coinbase, such as Ethereum and Litecoin. Coinbase is licensed as a cryptocurrency exchange in 42 U.S. states.

Binance is the leading global exchange for cryptocurrencies with an average trading volume of 2 billion per day.

In the past, Binance accounts weren't able to be funded with USD but that changed, and you can make deposits via SWIFT transfer.

Kraken is a San Francisco-based cryptocurrency exchange where investors can buy or sell cryptocurrencies using various fiat currencies, including U.S. dollars, euros, Canadian dollars, and the Japanese yen. More than a dozen virtual currencies can be traded via the Kraken exchange, including Bitcoin, Ethereum, EOS, and Monero.

As in the case of most crypto exchanges, investors need to establish and fund their digital wallet, which links to the trading account.

What Is a Simple Definition of Stock Exchange?

A stock exchange is a market that brings together buyers and sellers to facilitate investments in stocks.

What Are the 3 Major Stock Exchanges in the U.S.?

The New York Stock Exchange (NYSE) is the largest stock exchange in the U.S. and the world by market capitalization. The NASDAQ is the second-largest stock exchange in the U.S. while the American Stock Exchange, which is now known as NYSE Amex Equities after the acquisition by NYSE Euronext in 2008, is the third-largest in the U.S.

What Is the Difference Between Stock Exchange and Stock Market?

A stock exchange is a marketplace or the infrastructure that facilitates equity trading. On the other hand, a stock market is an umbrella term representing all of the stocks that trade in a particular region or country. A stock market is often represented as an index or grouping of various stocks such as the S&P 500.

What Is the Purpose of a Stock Exchange?

A stock exchange brings companies and investors together. A stock exchange helps companies raise capital or money by issuing equity shares to be sold to investors. The companies invest those funds back into their business, and investors, ideally, earn a profit from their investment in those companies.

The Bottom Line

Every stock must list on an exchange where buyers and sellers meet. The two big U.S. exchanges are the NYSE and the Nasdaq. Companies listed on either of these exchanges must meet various minimum requirements and baseline rules concerning the "independence" of their boards.

But these are by no means the only legitimate exchanges. Electronic communication networks are relatively new, but they are sure to grab a bigger slice of the transaction pie in the future. Finally, the OTC market is a fine place for experienced investors with an itch to speculate and the know-how to conduct a little extra due diligence.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1891 2023-09-05 00:08:01

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1895) Optician


Optician (UK also ophthalmic optician); (US optometrist) is someone whose job is examining people's eyes and selling glasses or contact lenses to correct sight problems.


An optician is an eye care specialist who helps you choose the right eyeglasses, contact lenses or other vision correction devices. They can’t diagnose or treat conditions that affect your eyes or vision. They’ll work with you to get the right corrective lenses after your optometrist or ophthalmologist gives you a prescription.

What is an optician?

An optician is an eye care specialist who helps you choose the right eyeglasses, contact lenses and other vision correction devices. They work with ophthalmologists and optometrists to take care of your eyes.

Your optician will help you find the right glasses or contacts after your optometrist or ophthalmologist prescribes them.

Is an optician a doctor?

Opticians aren’t medical doctors (MD) or doctors of osteopathy (DO). They don’t diagnose or treat issues that affect your eyes and vision.

Opticians are technicians who receive specialized training to help ophthalmologists and optometrists before, during and after your eye exam.

What are the educational requirements to be an optician?

In the U.S., every state has different laws and requirements for someone to be an optician. Opticians usually need a high school or equivalent diploma, depending on where they work.

Opticians in most states need a license to practice. License requirements are different in each state, but they usually require opticians to have a technical degree (like an associate’s degree). Many states require opticians to work a set amount of time (either a number of years or hours) before they’re fully licensed.

What does an optician do?

Opticians help you choose eyeglasses and contacts that fit your vision needs.

They’ll explain which options are available based on your prescription and any other conditions you have. Your optician will also fit your corrective lenses. They’ll adjust your eyeglass frames to fit your face and can show you how to wear your contacts safely.

Your optician will also assist your eye care specialist before, during and after your routine eye exam.

What kinds of eye problems does an optician treat?

Opticians can’t diagnose or treat conditions that affect your eyes. They work with optometrists and ophthalmologists, but don’t provide medical care.

Opticians use prescriptions from your optometrist or ophthalmologist to make and fit corrective lenses that will give you as close to 20/20 vision as possible.

When should I have my eyes examined?

Having your eyes and vision checked regularly can help an eye care specialist identify problems right away. How often you should get your eyes checked usually depends on your age:

Kids: A pediatrician should check your child’s eyes at every well-child visit until they’re old enough to start school, and then every one to two years.
Adults younger than 40: Every five to 10 years.
Adults between 40 and 54: Every two to four years.
Adults older than 55: Every one to three years.

You might need your eyes checked more often than this if you wear glasses or contacts or need another type of visual aid. People with diabetes also need their eyes checked more often than what’s listed here.

Ask an eye care specialist how often you need an eye exam.

How do I take care of my eyes?

Tell your provider about any changes in your vision. If you wear glasses or contact lenses, have your eyes examined regularly so your provider can adjust your prescription as often as necessary.

Talk to your provider if you notice any symptoms in your eyes, including:

Blurry vision.
Double vision (diplopia).
New pain that doesn’t go away in a few days.
Light sensitivity.
Your vision is getting noticeably worse.


What is the difference between an optician and an optometrist?

Opticians and optometrists work together to take care of your eyes and vision.

Optometrists can diagnose and treat issues in your eyes. They’ll also conduct your regular eye exams. They can’t perform surgery on your eyes. If you need eye surgery, your optometrist will refer you to an ophthalmologist.

Opticians work with optometrists and ophthalmologists. They’ll fit you for glasses, contacts or other vision correction aids. They can also adjust or replace your glasses, lenses or frames.

A note from a Clinic

An optician will work with you to make sure your glasses, contacts or other corrective lenses fit properly. They’ll show you how to use and care for your corrective lenses, and can adjust them if something doesn’t feel quite right.

Opticians don’t diagnose or treat new symptoms, so visit an optometrist, ophthalmologist or your regular healthcare provider if you notice your vision changing or experience new symptoms in or around your eyes.


An optician is an individual who fits eyeglasses or contact lenses by filling a refractive prescription from an optometrist or ophthalmologist. They are able to translate and adapt ophthalmic prescriptions, dispense products, and work with accessories. There are several specialties within the field.


Dispensing Optician or Ophthalmic Dispenser

A dispensing optician is anyone who prepares, fits, and dispenses prescription lenses, spectacles, eyeglasses, contact lenses, or any other type of vision-correcting optical device to the intended user. They may interpret optical prescriptions issued by an ophthalmologist, optometrist, or physician for the lab optician who fabricates vision-correcting optical lenses. They also measure inter-ocular or pupillary distances, vertex distances, pupil fitting heights, and frame angles to determine the proper position of vision-correcting lenses. In addition, they adapt, modify or align frames with vision-correcting lenses to the face of the intended wearer, Dispensing opticians must have a basic knowledge of laboratory techniques such as lens surfacing and lens preparation.

Mechanical Optician, Lab Optician, or Ophthalmic Lab Technician

Ophthalmic laboratory technicians must understand optics and how to use machinery in order to surface, coat, edge, or finish lenses according to specifications provided by dispensing opticians. They typically insert lenses into frames, also called glazing, to produce finished glasses and conduct all quality and safety testing required by the respective local and country regulations. Although most lenses are designed with fully automated equipment, such as computer-based generators, automatic edgers, and lens measurement instruments, a highly-skilled lab optician will often finish lenses by hand for more difficult prescriptions and lens designs in order to have the best-finished outcome.

Contact Lens Fitter or Contact Lens Technician

Contact Lens Fitters may work independently or under the direction of an ophthalmologist or optometrist to fill a doctor's prescription for contact lenses. A patient must obtain a prescription for contact lenses from a physician and then the fitter will review contact lens handling, fitting, and follow-up care. Contact lens fitters must have computer skills, communication skills, and an understanding of medical-legal implications.


An ocularist is a trained technician who specializes in fitting a patient with a prosthetic eye after management by an ophthalmologist. Ocularists are trained in assessing the status of the orbit, fabricating and fitting a cosmetic ocular prosthesis, and periodically monitoring the prosthesis and related tissues. They ensure the correct fitting, shaping, and painting of ocular prostheses. The ocularist also educates the patient on handling and care of the prosthesis. Ocularists provide long-term care through follow-up examinations for evaluation and polishing of prostheses.

Work Environment:

Corporate Practice

Corporate practices may require more night and weekend work hours than other work environments due to the longer hours of the corporate chains. Many who work for them report the trade-off is greater room for growth, higher pay, and better benefits due to the larger scale of the employer. Purchasing of goods is conducted by the corporate headquarters and not by individuals at the locations.

Independent Practice

Owned by the optician themselves, opticians who operate independent practices have all of the responsibilities of an entrepreneur/business owner as well as an optician. In the United States, due to certain local and state regulations, opticians cannot employ optometrists in various areas and are limited in some vision discount plans they can accept. This means they must rely more heavily on walk-in consumers than those who are owned by a doctor.

Optometrist or Ophthalmologist Office

A smaller, more intimate environment than corporate or clinical, doctor-owned practices usually do not require as many evening or weekend hours as corporate locations; however, every medical office is different and will have a unique set of features and characteristics.

Hospitals / Clinics Program Description

Opticians working in a hospital or clinic typically oversee patient care, administer treatment and operate medical equipment under the supervision of an ophthalmologist or optometrist.

Lab Manufacturing

This role typically does not work directly with patients and it is centered around the use of high-tech equipment and hand-held tools.

History of opticians and spectacle makers

The first known artistic representation of eyeglasses was painted by Tommaso da Modena in 1352. He did a sequence of frescoes of brothers efficiently reading or replicating manuscripts; one holds a magnifying glass while the other has glasses suspended on his nose. Once Tommaso had established the example, other painters positioned spectacles on the noses of many of subjects, almost certainly as a representation of wisdom and respect.

One of the most noteworthy developments in spectacle production in the 15th century was the introduction of concave lenses for the myopic or nearsighted. Pope Leo X, who was very myopic, wore concave spectacles when hunting and professed they enabled him to see clearer than his cohorts.

The first spectacles utilized quartz lenses since optical glass had not been developed. The lenses were set into bone, metal and leather mountings, frequently fashioned like two small magnifying glasses with handles riveted together and set in an inverted V shape that could be balanced on the bridge of the nose. The use of spectacles extended from Italy to Germany, Spain, France and Portugal.

From their inception, eyeglasses posed a dilemma that wasn't solved for almost 350 years: how to keep them on the bridge of the nose without falling. Spanish spectacle makers of the 17th century experimented with ribbons of silk that could be attached to the frames and then looped over the ears. Spanish and Italian missionaries carried the new models to spectacle wearers in China. The Chinese attached little ceramic or metal weights to the strings instead of making loops. In 1730 a London optician named Edward Scarlett perfected the use of rigid sidepieces that rested atop the ears. This perfection rapidly spread across the continent. In 1752 James Ayscough publicized his latest invention, spectacles with double hinged side pieces. These became very popular and appear more often than any other kind in paintings and prints of the period. Lenses were fabricated of tinted glass as well as clear. Ayscough felt that the clear glass lenses gave an unpleasant glare. In Spain in 1763 Pablo Minguet recommended turquoise, green, or yellow lenses but not amber or red.

Europeans, in particular the French, were self-conscious about the use of eyeglasses. Parisian aristocrats used reading aids only in private. The gentry of England and France used a "perspective glass” or monocular which could be concealed from view easily. In Spain, however, spectacles were popular amongst all classes since they considered eyeglasses made them look more important and dignified.

Far-sighted or aging colonial Americans imported spectacles from Europe. Spectacles were primarily for the affluent and literate colonists, who required a valuable and precious appliance. Benjamin Franklin in the 1780s developed the bifocals. Bifocal lenses advanced little in the first half of the 19th century. The terms bifocal and trifocal were introduced in London by John Isaac Hawkins, whose trifocals were patented in 1827. In 1884 B. M. Hanna was granted patents on two forms of bifocals which become commercially standardized as the "cemented" and "perfection" bifocals. Both had the serious faults of ugly appearance, fragility, and dirt-collection at the dividing line. At the end of the 19th century the two sections of the lens were fused instead of cemented At the turn of the 20th century, there was a considerable increase in the use of bifocals.

Between 1781 and 1789, silver spectacles with sliding extension temples were being fabricated in France; however it was not until the 19th century that they gained extensive popularity. John McAllister of Philadelphia began fabricating spectacles with sliding temples containing looped ends which were much easier to use with the then-popular wigs. The loops supplement the inadequacy of stability, by allowing the addition of a cord or ribbon which could be tied behind the head, thus holding the eyeglasses firmly in place.

In 1826, William Beecher moved to Massachusetts from Connecticut to establish a jewellery-optical manufacturing shop. The first ophthalmic pieces he fabricated were silver spectacles, which were later followed by blue steel. In 1869 the American Optical Company was incorporated and acquired the holdings of William Beecher. In 1849 J. J. Bausch immigrated to the United States from Germany. He had already served an apprenticeship as an optician in his native land and had found work in Berne. His reimbursement for the labor on a complete pair of spectacles was equal to six cents. Mr. Bausch encountered difficult times in America from 1849 until 1861, at which time war broke out. When the war prevented import of eyeglass frames, demand for his hard rubber frames skyrocketed. Continuous expansion followed and the large Bausch and Lomb Company was formed.

The monocle, which was first called an "eye-ring", was initially introduced in England in the early 19th century; although it had been developed in Germany during the 18th century. A young Austrian named Johann Friedrich Voigtländer [de] studied optics in London and took the monocle idea back to Germany with him. He started making monocles in Vienna about 1814 and the fashion spread and took particularly strong roots in Germany and in Russia. The first monocle wearers were upper-class gentlemen, which may account for the aura of arrogance the monocle seemed to confer on the wearer. After World War I, the monocle fell into disrepute, its downfall in the allied sphere hastened, no doubt, by its association with the German military.

The lorgnette, two lenses in a frame the user held with a lateral handle, was another 18th-century development (by Englishman George Adams). The lorgnette almost certainly developed from the scissors-glass, which was a double eyeglass on a handle. Given that the two branches of the handle came together under the nose and looked as if they were about to cut it off, they were known as binocles-ciseaux or scissors glasses. The English altered the size and form of the scissors-glasses and produced the lorgnette. The frame and handle were often artistically embellished, given that they were used mostly by women and more often as a piece of jewellery than as a visual aid. The lorgnette maintained its popularity with ladies of fashion, who chose not to wear spectacles. The lorgnette maintained its popularity to the end of the 19th century.

Pince-nez are believed to have appeared in the 1840s, but in the latter part of the century there was a great upsurge in the popularity of the pince-nez for both men and women. Gentlemen wore any style which suited them—heavy or delicate, round, or oval, straight, or drooping—usually on a ribbon, cord, or chain about the neck or attached to the lapel. Ladies more often than not wore the oval rimless style on a fine gold chain which could be reeled automatically into a button-size eyeglass holder pinned to the dress. Whatever the disadvantage of the pince-nez, it was convenient.

In the 19th century, the responsibility of choosing the correct lens lay, as it always had, with the customer. Even when the optician was asked to choose, it was often on a rather casual basis. Spectacles were still available from travelling salesmen. Spectacles with large round lenses and tortoise shell frames became the fashion around 1914. The enormous round spectacles and the pince-nez continued to be worn in the twenties. In the thirties there was increased emphasis on style in glasses with a variety of spectacles available. Meta Rosenthal wrote in 1938 that the pince-nez was still being worn by dowagers, headwaiters, old men, and a few others. The monocle was worn by only a minority in the United States. Sunglasses, however, became very popular in the late '30s.


Opticians use a variety of equipment to fit, adjust and dispense eyewear, contact lenses, and low-vision aids.

Manual Lensmeter

Technically identified by the generic term manual lensmeter, opticians may often refer to this piece of equipment as a lensometer, focimeter, or vertometer. The modern lensmeter was invented in 1922 by Edgar Derry Tillyer of American Optical to determine "whether lenses have the refraction and power prescribed." Proper use of the lensometer by a dispensing optician or a lab optician includes verifying back or front vertex power, orientating uncut lenses for finishing and glazing, and confirming the mounting of lenses into the frame. Manual lensmeters can also be outfitted with an attachment to read the back vertex power of a contact lens for modification and verification purposes.

The optician uses the refracted, or bent light, displayed within a lensmeter to interpret the sphere, cylinder, and add powers (if prescribed), axis orientation, prismatic effect, and locate the major reference point of the lens. Correct interpretation of these readings is critical to the performance of the eyewear and user satisfaction.

Automated Lensmeter

An automated lensmeter uses the reflected wavelength of green light off of the lens surface along every lens meridian in order to determine all of the data points that the optician interprets with the manual lensometer. The benefits of an automated lensmeter are increased speed, adjustments for variables in the index of refraction in the lens material, the ability to measure UV and light transmittance, and a decrease in training time while on the job. The drawbacks of automated lensmeters in comparison to manual lensmeters are greater difficulty identifying higher prismatic errors, aberrations, and surfacing power errors (optic waves), and the necessity of the optician not to tip the lens to avoid an erroneous result.

Corneal Reflex Pupilometer

A corneal reflex pupilometer is a digital device used to measure Interpupillary Distance (IPD), otherwise known as Pupillary Distance (PD). The measurement is used to align the Major Reference Point (MRP) of the lenses along the visual axis to reduce unwanted prismatic effect, eyestrain, and lens aberrations.

A PD can be taken Binocularly (from the corneal reflex of one pupil to the corneal reflex of the other) or Monocularly (from the center of the spectacle bridge to the center of the corneal reflex of each eye independently with the non-measured eye being occluded). By providing a rest point on the bridge similar to an eyeglass frame, pupilometers provided a proper reference point for obtaining an accurate monocular PD value.

PDs are also taken in relation to focus point. The eyes can be focused at infinity (distance), focused near (approximately 16 inches or 40 centimeters), or intermediate (a working distance in between near and distance. Because a pupilometer can be dialed to a specific distance and easily occluded, it is often easier to work with. This does not mean that it is more accurate than a skilled optician with a corneal reflex light, a millimeter ruler called a PD stick, and fully adjusted eyewear for certain age groups and pathologies. While a ruler alone is susceptible to parallax error, when it is used in conjunction with the other tools previously mentioned the accuracy can exceed the pupilometer for these certain patient groups.

The fitting and dispensing of contact lenses requires the use of additional equipment, all with very specific purposes. A keratometer is a diagnostic instrument for measuring the curvature of the anterior surface of the cornea, particularly for assessing the extent and axis of astigmatism. It was invented by the French ophthalmologist Samuel Hankins in 1880. Opticians, like ophthalmologists and optometrists, also use a slit-lamp/bio-microscope to examine the anterior segment, or frontal structures and posterior segment, of the human eye, which includes the eyelid, sclera, conjunctiva, iris, natural crystalline lens, and cornea. The binocular slit-lamp examination provides stereoscopic magnified view of the eye structures in detail, enabling anatomical diagnoses to be made for a variety of eye conditions.

While a patient is seated in the examination chair, he rests his chin and forehead on a support to steady the head. Using the biomicroscope, the optician then proceeds to examine the patient's eye. A fine strip of paper, stained with fluorescein, a fluorescent dye, may be touched to the side of the eye; this stains the tear film on the surface of the eye to aid examination. The dye is naturally rinsed out of the eye by tears. Adults need no special preparation for the test; however children may need some preparation, depending on age, previous experiences, and level of trust.

The list of equipment used by an optician is extensive and is often specified in jurisdiction specific Professional Standards of Practice.[ The standards of the College of Opticians of British Columbia serve as an example.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1892 2023-09-06 00:12:13

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1896) Ophthalmology


Ophthalmology is the branch of medicine concerned with the diagnosis and treatment of disorders of the eye.


Ophthalmology is the medical specialty dealing with the diagnosis and treatment of diseases and disorders of the eye. The first ophthalmologists were oculists. These paramedical specialists practiced on an itinerant basis during the Middle Ages. Georg Bartisch, a German physician who wrote on eye diseases in the 16th century, is sometimes credited with founding the medical practice of ophthalmology. Many important eye operations were first developed by oculists, as, for example, the surgical correction of strabismus, first performed in 1738. The first descriptions of visual defects included those of glaucoma (1750), night blindness (1767), colour blindness (1794), and astigmatism (1801).

The first formal course in ophthalmology was taught at the medical school of the University of Göttingen in 1803, and the first medical eye clinic with an emphasis on teaching, the London Eye Infirmary, was opened in 1805, initiating the modern specialty. Advances in optics by the Dutch physician Frans Cornelis Donders in 1864 established the modern system of prescribing and fitting eyeglasses to a particular vision problem. The invention of the ophthalmoscope for looking at the interior of the eye created the possibility of relating eye defects to internal medical conditions.

In the 20th century, advances in the field have chiefly involved the prevention of eye disease through regular eye examinations and the early treatment of congenital eye defects. Another major development was the eye bank, first established in 1944 in New York, which made corneal tissues for transplantation more generally available.

The function of the human eye is to receive visual images. Whatever adversely affects vision is the concern of the ophthalmologist, whether it be caused by faulty development of the eye, disease, injury, degeneration, senescence, or refraction. He makes tests of visual function and examines the interior of the eye as part of a general physical examination for symptoms of systemic or neurologic diseases. He prescribes medical treatment for eye disease and glasses for refraction and performs surgical operations where indicated.


Ophthalmology  is a surgical subspecialty within medicine that deals with the diagnosis and treatment of eye disorders.

An ophthalmologist is a physician who undergoes subspecialty training in medical and surgical eye care. Following a medical degree, a doctor specialising in ophthalmology must pursue additional postgraduate residency training specific to that field. This may include a one-year integrated internship that involves more general medical training in other fields such as internal medicine or general surgery. Following residency, additional specialty training (or fellowship) may be sought in a particular aspect of eye pathology.

Ophthalmologists prescribe medications to treat ailments, such as eye diseases, implement laser therapy, and perform surgery when needed. Ophthalmologists provide both primary and specialty eye care - medical and surgical. Most ophthalmologists participate in academic research on eye diseases at some point in their training and many include research as part of their career. Ophthalmology has always been at the forefront of medical research with a long history of advancement and innovation in eye care.

Ophthalmology/Ophthalmologist is in the same field as Optometry/Optometrists, but the activities differ.


A brief list of some of the most common diseases treated by ophthalmologists:

* Cataract
* Excessive tearing (tear duct obstruction)
* Proptosis (bulged eyes)
* Thyroid eye disease
* Eye tumors
* Ptosis
* Diabetic retinopathy
* Dry eye syndrome
* Glaucoma
* Macular degeneration
* Retinal detachment
* Endophthalmitis
* Refractive errors
* Strabismus (misalignment or deviation of eyes)
* Uveitis
* Ocular trauma
* Ruptured globe injury
* Orbital fracture

The most valued pharmaceutical companies worldwide whose leading products are in Ophthalmology are Regeneron (United States) for AMD treatment and Bausch Health (Canada) for Front of eye.


Eye examination

Following are examples of examination methods performed during an eye examination that enables diagnosis:

* Visual acuity assessment
* Ocular tonometry to determine intraocular pressure
* Extraocular motility and ocular alignment assessment
* Slit lamp examination
* Dilated fundus examination
* Gonioscopy
* Refraction

Specialized tests

* Optical coherence tomography (OCT) is a medical technological platform used to assess ocular structures. The information is then used by physicians to assess staging of pathological processes and confirm clinical diagnoses. Subsequent OCT scans are used to assess the efficacy of managing diabetic retinopathy, age-related macular degeneration, and glaucoma.

* Optical coherence tomography angiography (OCTA) and Fluorescein angiography to visualize the vascular networks of the retina and choroid.

* Electroretinography (ERG) measures the electrical responses of various cell types in the retina, including the photoreceptors (rods and cones), inner retinal cells (bipolar and amacrine cells), and the ganglion cells.

* Electrooculography (EOG) is a technique for measuring the corneo-retinal standing potential that exists between the front and the back of the human eye. The resulting signal is called the electrooculogram. Primary applications are in ophthalmological diagnosis and in recording eye movements.

* Visual field testing to detect dysfunction in central and peripheral vision which may be caused by various medical conditions such as glaucoma, stroke, pituitary disease, brain tumours or other neurological deficits.

* Corneal topography is a non-invasive medical imaging technique for mapping the anterior curvature of the cornea, the outer structure of the eye.

* Ultrasonography of the eyes may be performed by an ophthalmologist.

Ophthalmic surgery

Eye surgery, also known as ocular surgery, is surgery performed on the eye or its adnexa by an ophthalmologist. The eye is a fragile organ, and requires extreme care before, during, and after a surgical procedure. An eye surgeon is responsible for selecting the appropriate surgical procedure for the patient and for taking the necessary safety precautions.


Ophthalmology includes subspecialities that deal either with certain diseases or diseases of certain parts of the eye. Some of them are:

* Anterior segment surgery
* Cornea, ocular surface, and external disease
* Glaucoma
* Neuro-ophthalmology
* Ocular oncology
* Oculoplastics and orbit surgery
* Ophthalmic pathology
* Paediatric ophthalmology/strabismus (misalignment of the eyes)
* Refractive surgery
* Medical retina, deals with treatment of retinal problems through non-surgical means
* Uveitis
* Veterinary specialty training programs in veterinary ophthalmology exist in some countries.
* Vitreo-retinal surgery, deals with surgical management of retinal and posterior segment diseases

Medical retina and vitreo-retinal surgery sometimes are combined and together they are called posterior segment  subspecialisation.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1893 2023-09-07 00:06:02

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1897) Optometry


Optometry is health-care profession concerned with examining the eyes for defects of vision and diagnosing and treating such conditions. Optometrists prescribe and supply eyeglasses, contact lenses, and other optical aids that correct the focusing of the eyes.


Optometry is a health-care profession concerned with examining the eyes for defects of vision and diagnosing and treating such conditions. Optometrists prescribe and supply eyeglasses, contact lenses, and other optical aids that correct the focusing of the eyes. They also examine the eyes to detect such disorders as glaucoma and cataracts. In addition, optometrists counsel people on the correct use and care of the eyes, supervise exercise and training programs that are designed to treat problems of vision, and help rehabilitate patients who have low or severely restricted vision. Unlike the ophthalmologist, who is a physician with a specialization in the diagnosis and treatment of eye diseases (and who may also test vision and prescribe corrective lenses), the optometrist generally is not trained to perform surgery. In some areas, however, optometrists are licensed to use topical therapeutic drugs and to treat glaucoma and other eye diseases with systemic drugs.

Requirements for the practice of optometry vary. In the United States professional optometrists must complete a four-year course of study in addition to two to four years of undergraduate work and must be licensed by the state in which they practice. Schools of optometry are accredited nationally by the Council on Optometric Education and grant the Doctor of Optometry (O.D.) degree.

The optician, another optical specialist, makes, fits, and sells optical devices, particularly the corrective lenses prescribed by optometrists and ophthalmologists.


Optometry is a specialized health care profession that involves examining the eyes and related structures for defects or abnormalities. Optometrists are health care professionals who typically provide comprehensive primary eye care.

In the United States and Canada, optometrists are those that hold a Doctor of Optometry degree. They are trained and licensed to practice medicine for eye related conditions, in addition to providing refractive (optical) eye care. In the United Kingdom, optometrists may also practice medicine (and provide refractive care) for eye related conditions. The Doctor of Optometry title can also be used in the UK for those that hold the postgraduate O.D. degree. Within their scope of practice, optometrists are considered physicians and bill medical insurance(s) (example: Medicare) accordingly. Moreover, many participate in academic research for eye-related conditions and diseases. Optometrists are the only health care professionals with a first professional degree specific to eye care; ophthalmologists are physicians who typically hold a four-year college degree, a medical degree, and at least three years of residency training after medical school, obviating the need for an eye-specific qualification.


The term "optometry" comes from the Greek words (opsis; "view") and (metron; "something used to measure", "measure", "rule"). The word entered the language when the instrument for measuring vision was called an optometer, (before the terms phoropter or refractor were used). The root word opto is a shortened form derived from the Greek word ophthalmos meaning, "eye." Like most healthcare professions, the education and certification of optometrists are regulated in most countries. Optometric professionals and optometry-related organizations interact with governmental agencies, other healthcare professionals, and the community to deliver eye and vision care.

Definition of optometry and optometrist

The World Council of Optometry, World Health Organization and about 75 optometry organizations from over 40 countries have adopted the following definition, to be used to describe optometry and optometrist.

Optometry is a healthcare profession that is autonomous, educated, and regulated (licensed/registered), and optometrists are the primary healthcare practitioners of the eye and visual system who provide comprehensive eye and vision care, which includes refraction and dispensing, detection/diagnosis and management of disease in the eye, and the rehabilitation of conditions of the visual system.


A partial list of the common diseases Optometrists diagnose/manage:

* Cataracts
* Dry Eye Syndrome
* Eye tumors
* Glaucoma
* Diabetic retinopathy
* Hypertensive retinopathy
* Macular degeneration
* Refractive errors
* Corneal disease
* Strabismus
* Amblyopia
* Uveitis


Eye examination

Following are examples of examination methods performed during an eye examination that enables diagnosis

* Ocular tonometry to determine intraocular pressure
* Refraction assessment
* Retina examination
* Slit lamp examination
* Visual acuity

Specialized tests

Optical coherence tomography (OCT) is a medical technological platform used to assess ocular structures. The information is then used by eye doctors to assess staging of pathological processes and confirm clinical diagnoses. Subsequent OCT scans are used to assess the efficacy of managing diabetic retinopathy, age-related macular degeneration, and glaucoma.

Additional Information

Optometrists are self-reliant superior healthcare specialists, who are licensed to detect, diagnose, and provide treatment for diseases and disorders related to the eyes and the visual system. Optometrists were formerly known as ophthalmic opticians.

They performed all the work that was performed by ophthalmologists, except surgery. Optometrists work in hospitals, clinics, the ophthalmic industry, teaching institutions, and on research projects; however, they majorly contribute their services in clinical practice, hospitals, and public health centers.

Role of optometrists in clinical practice

Clinically, optometrists aim to provide solutions to patients with eye disorders. First, patients are subjected to general eye examinations in which the optometrist takes the patient’s medical history of his eye problems. Following this, the eyes are checked for refractive errors and a visual acuity test is carried out to evaluate the eyesight. if required, spectacles or contact lenses of the calculated refractive status of the eyes are prescribed, in order to attain proper vision.

Role of optometrists in clinical practice
Clinically, optometrists aim to provide solutions to patients with eye disorders. First, patients are subjected to general eye examinations in which the optometrist takes the patient’s medical history of his eye problems. Following this, the eyes are checked for refractive errors and a visual acuity test is carried out to evaluate the eyesight. if required, spectacles or contact lenses of the calculated refractive status of the eyes are prescribed, in order to attain proper vision.

In addition to visual testing, optometrists perform the following functions:

* Observance of eye disease: Using the ophthalmoscope, optometrists detect diseases related to the eyes such as glaucoma, macular degeneration, and other diseases that are associated with eye functions such as diabetes and hypertension. If irregularities persist in the detection, the patient is subjected to further special tests. For example, estimation of eye pressure in patients with glaucoma.

* Prescribing drugs for diseases: For management of ocular disorders and treatment of glaucoma, optometrists are certified to prescribe the topical form of pharmaceutical drugs like antibiotics, antihistamines, non-steroidal anti-inflammatory, and some scheduled analgesics. Only optometrists in Florida, New York, and Massachusetts can prescribe the oral form of these drugs.

* Independent prescribing: Optometrists, after certification by an independent prescribing qualification, are authorized to prescribe all licensed drugs except parenterals (injectables). This kind of practice is followed among optometrists in the UK.

* Contact lens professionals: Optometrists who are professionals in handling contact lenses for abnormal shape of cornea also prescribe special contact lenses like toric and varifocal lenses for patients.

Role of optometrists in the hospital

The duties of optometrists inside the hospital are vast. They perform functions identical to those done in the clinic in addition to many others. They provide outpatient care for a portion of the patients in eye hospitals.

Provide primary eye care for outpatients: An optometrist basically tests the vision sharpness, prescribes corrective lenses, and is an expert in handling equipment that is used to examine the eyes of the patient.

* Optometrists in low vision care: Optometrists routinely deal with patients with irreversible eyesight, and provide low vision care medication to enhance recovery. They also educate the patient about the regular visual exercises to be practiced to improve their vision.
* Optometrists in binocular vision care: Optometrists personalize vision therapy for patients suffering from binocular abnormalities; these are required by students and sportspersons involved in this field.
* Counseling and review of patients: Optometrists provide counseling to cataract patients undergoing pre- or postsurgical operation and also counsel patients about the appropriate usage of contact lens. Previous medical records of the patient are reviewed to assess their vision status.
* Work with other medical specialists: Complete assessment of eye functions by optometrists enables the pediatric ophthalmologist to efficaciously address amblyopia in children. The integrated eye care model enables both optometrists and ophthalmologists to work together to enhance good care of patients.
* Research and training: Optometrists involve in research practices on vision disorders that arise due to neurological defects. Their work is to provide evidence of their findings on patients with binocular vision, amblyopia, and other vision disorders. Experienced optometrists provide teaching and training to new professionals in the field.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1894 2023-09-08 00:12:37

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1898) Mask


Mase is a covering for all or part of the face that protects, hides, or decorates the person wearing it.


Layered prevention strategies — like staying up to date on vaccines and wearing masks — can help prevent severe illness and reduce the potential for strain on the healthcare system. Wear a mask with the best fit, protection, and comfort for you.

It is important to wear a mask or respirator when you are sick or caring for someone who is sick with COVID-19. When caring for someone who is sick with COVID-19, a respirator will provide you the best level of protection.

Considerations for specific groups of people:

People at higher risk for severe illness

Some people are more likely to become very sick with COVID-19

* People who are older
* People with certain medical conditions
* Pregnant and recently pregnant people

People at increased risk, and those who live with or visit them, should

* Talk to their healthcare provider about whether they and the people around them should wear a mask or respirator when the COVID-19 hospital admission level is medium. 

* Wear a mask or respirator that provides them with greater protection when the COVID-19 hospital admission level is high.


Children ages 2 years and older can wear masks or respirators to protect themselves and others from COVID-19.

Choose a high-quality and comfortable mask or respirator that your child can wear properly. A poorly fitting or uncomfortable mask or respirator might be worn incorrectly or removed often, and that would reduce its intended benefits.

* Choose a size that fits over the child’s nose and under the chin but does not impair vision.
* Follow the user instructions for the mask or respirator. These instructions may show how to make sure the product fits properly.
* Some types of masks and respirators may feel different if your child is used to wearing cloth or disposable procedure masks.

Parents and caregivers may have questions about NIOSH-approved respirators (such as N95s), and international respirators (such as KN95s and KF94s) for children. Although respirators may be available in smaller sizes, they are typically designed to be used by adults in workplaces, and therefore may not have been tested for broad use in children.

Safety precautions

* If your child has a medical condition, such as a heart or lung problem, ask their healthcare provider before they use methods to improve mask fit or use an ASTM F3502 mask or a respirator.

* If your child has a hard time breathing, gets dizzy, or has other symptoms while you are trying to get the mask to fit better or when using an ASTM F3502 mask or a respirator, choose a cloth or disposable mask. They should continue to protect themselves and others. Consult your healthcare provider if these symptoms do not resolve.

People with disabilities

Certain groups of people may find it difficult to wear a mask, including people of any age with certain disabilities.

Challenges may be caused by being sensitive to materials on the face, difficulty understanding the importance of mask wearing for protection, or having difficulty controlling behavior to keep the mask in place.

People with certain disabilities or their caregivers can assess whether they need to wear a mask. They should do this by considering the person’s ability to:

* Wear a mask correctly (proper mask size and fit)
* Avoid frequent touching of the mask and face
* Limit sucking, drooling, or having excess saliva on the mask
* Remove the mask without assistance

People who are deaf or hard of hearing

These individuals may consider:

* Wearing a clear mask or a cloth mask with a clear panel
* If a clear mask is not available, using written communication, closed captioning, or decreasing background noise to make communication possible while wearing a mask that blocks lips


Wearing a high-quality mask while you travel can help protect you and others.

Disposable masks and cloth masks: Untie the strings behind your head or stretch the ear loops and fold the outside corners together.

Respirators: Follow the manufacturer’s instructions.

1. If your cloth mask is wet or dirty, put it in a sealed plastic bag until you can wash it. This will keep it from getting moldy.

2. (i) If your cloth mask is dry and clean, you can store it in a breathable bag (like a paper or mesh fabric bag) to keep it clean between uses in the same day.

(ii) Cloth masks should be washed at least once a day or as soon as they become wet or dirty. You can either wash and dry your masks by hand or use a washer and dryer.

(iii) Wash or sanitize your hands after removing any mask.

Taking off your mask while you eat or drink

If you are taking off your mask to eat or drink outside of your home, you can place it somewhere safe to keep it clean, such as your pocket, purse, or paper bag. After eating, put the mask back on with the same side facing out. Be sure to wash or sanitize your hands again after taking off your mask and after putting your mask back on.

When to throw away or change your mask

* Disposable masks should be thrown away after they’re worn once.
* If you use respirators, check the manufacturer’s instructions to learn how long they can be worn before they should be thrown away.
* Disposable masks and respiratorsthat become wet or dirty should be thrown away in the trash right away. Do not continue to wear a wet or dirty mask. Replace it with a dry, clean mask.


Masks in theatre

Masks play a key part within world theatre traditions, particularly non-western theatre forms. They also continue to be a vital force within contemporary theatre, and their usage takes a variety of forms.

In many cultural traditions, the masked performer is a central concept and is highly valued. In the western tradition, actors in Ancient Greek theatre wore masks, as they do in traditional Japanese Noh drama. In some Greek masks, the wide and open mouth of the mask contained a brass megaphone enabling the voice of the wearer to be projected into the large auditoria. In medieval Europe, masks were used in mystery and miracle plays to portray allegorical creatures, and the performer representing God frequently wore a gold or gilt mask. During the Renaissance, masques and ballet de cour developed – courtly masked entertainments that continued as part of ballet conventions until the late eighteenth century. The masked characters of the Commedia dell'arte included the ancestors of the modern clown. In contemporary western theatre, the mask is often used alongside puppetry to create a theatre that is essentially visual, rather than verbal, and many of its practitioners have been visual artists.

Masks are an important part of many theatre forms throughout world cultures, and their usage in theatre has often developed from, or continues to be part of old, highly sophisticated, stylized theatrical traditions.

Contemporary theatre

Masks and puppets were often incorporated into the theatre work of European avant-garde artists from the turn of the nineteenth century. Alfred Jarry, Pablo Picasso, Oskar Schlemmer, other artists of the Bauhaus School, as well as surrealists and Dadaists, experimented with theatre forms and masks in their work.

In the 20th century, many theatre practitioners, such as Meyerhold, Edward Gordon Craig, Jacques Copeau, and others in their lineage, attempted to move away from Naturalism. They turned to sources such as Oriental Theatre (particularly Japanese Noh theatre) and commedia dell'arte, both of which forms feature masks prominently.

Edward Gordon Craig (1872–1966) in A Note on Masks (1910) proposed the virtues of using masks over the naturalism of the actor. Craig was highly influential, and his ideas were taken up by Brecht, Cocteau, Genet, Eugene O'Neill – and later by Arden, Grotowski, Brook, and others who "attempted to restore a ritualistic if not actually religious significance to theatre".

Copeau, in his attempts to "Naturalise" actors, decided to use masks to liberate them from their "excessive awkwardness". In turn, Copeau's work with masks was taken on by his students including Etienne Decroux and later, via Jean Daste and Jacques Lecoq. Lecoq, having worked as movement director at Teatro Piccalo in Italy, was influenced by the Commedia tradition. Lecoq met Amleto Satori, a sculptor, and they collaborated on reviving the techniques of making traditional leather Commedia masks. Later, developing Copeau's "noble mask", Lecoq would ask Satori to make him masques neutre (the neutral mask). For Lecoq, masks became an important training tool, the neutral mask being designed to facilitate a state of openness in the student-performers, moving gradually on to character and expressive masks, and finally to "the smallest mask in the world" the clown's red-nose. One highly important feature of Lecoq's use of mask, wasn't so much its visual impact on stage, but how it changed the performers movement on stage. It was a body-based approach to mask work, rather than a visually led one. Lecoq's pedagogy has been hugely influential for theatre practitioners in Europe working with mask and has been exported widely across the world. This work with masks also relates to performing with portable structures and puppetry. Students of Lecoq have continued using masks in their work after leaving the school, such as in John Wright's Trestle Theatre.

In America, mask-work was slower to arrive, but the Guerrilla Theatre movement, typified by groups such as the San Francisco Mime Troupe and Bread and Puppet Theatre took advantage of it. Influenced by modern dance, modern mime, Commedia dell'arte and Brecht such groups took to the streets to perform highly political theatre. Peter Schumann, the founder of Bread and Puppet theatre, made particular use of German Carnival masks. Bread and Puppet inspired other practitioners around the world, many of whom used masks in their work. In the US and Canada, these companies include In the Heart of the Beast Puppet and Mask Theater of Minneapolis; Arm-of-the Sea Theatre from New York State; Snake Theater from California; and Shadowland Theatre of Toronto, Ontario. These companies, and others, have a strong social agenda, and combine masks, music and puppetry to create a visual theatrical form. Another route masks took into American Theatre was via dancer/choreographers such as Mary Wigman, who had been using masks in dance and had emigrated to America to flee the Nazi regime.

In Europe, Schumann's influence combined with the early avant-garde artists to encourage groups such as Moving Picture Mime Show and Welfare State (both in the UK). These companies had a big influence on the next generation of groups working in visual theatre, including IOU and Horse and Bamboo Theatre, who create a theatre in which masks are used along with puppets, film and other visual forms, with an emphasis on the narrative structure.

Functional masks

Masks are also familiar as pieces of kit associated with practical functions, usually protective. There has been a proliferation of such masks recently but there is a long history of protective armour and even medical masks to ward off plague. The contrast with performance masks is not always clear-cut. Ritual and theatrical masks themselves can be considered to be practical, and protective masks in a sports context in particular are often designed to enhance the appearance of the wearer.


Some masks are used for medical purposes:

* Oxygen mask, a piece of medical equipment that assists breathing.
* Anesthetic mask.
* Burn mask, a piece of medical equipment that protects the burn tissue from contact with other surfaces, and minimises the risk of infection.
* Surgical mask, a piece of medical equipment that helps to protect both the surgeon and patient from acquiring infection from each other.
* Face shield, to protect a medical professional from bodily fluids.
* Pocket mask or CPR mask, used to safely deliver rescue breaths during a cardiac arrest or respiratory arrest.
* Cloth face mask, an alternative to a surgical mask for reducing the spread of infectious agents.


Protective masks are pieces of kit or equipment worn on the head and face to afford protection to the wearer, and today usually have these functions:

* Providing a supply of air or filtering the outside air (respirators and dust masks).
* Protecting the face against flying objects or dangerous environments, while allowing vision.

In Roman gladiatorial tournaments masks were sometimes used. From archaeological evidence it is clear that these were not only protective but also helped make the wearer appear more intimidating. In medieval Europe and in Japan soldiers and samurai wore similarly ferocious-looking protective armour, extending to face-masks. In the 16th century, the Visard was worn by women to protect from sunburn. Today this function is attributed to thin balaclavas.

In sport the protective mask will often have a secondary function to make the wearer appear more impressive as a competitor.

Before strong transparent materials such as polycarbonate were invented, visors to protect the face had to be opaque with small eyeslits, and were a sort of mask, as often in mediaeval suits of armour, and (for example) Old Norse grímr meant "mask or visor".


Masks are sometimes used to avoid recognition. As a disguise the mask acts as a form of protection for the wearer who wishes to assume a role or task without being identified by others.

Robbers and other criminal perpetrators may wear masks as a means in concealing their faces and thus identities from their victims and from law enforcement.

Occasionally a witness for the prosecution appears in court in a mask to avoid being recognized by associates of the accused.

Participants in a black bloc at protests usually wear masks, often bandannas, to avoid recognition, and to try to protect against any riot control agents used.

Masks are also used to prevent recognition while showing membership of a group:

* Masks are use by penitents in ceremonies to disguise their identity in order to make the act of penitence more selfless. * The Semana Santa parades throughout Spain and in Hispanic or Catholic countries throughout the world are examples of this, with their cone-shaped masks known as capirote.
* Masks are used by vigilante groups.
* The cone-shaped mask in particular is identified with the Ku Klux Klan in a self-conscious effort to combine the hiding of personal identity with the promotion of a powerful and intimidating image.
* Members of the group Anonymous frequently wear masks (usually Guy Fawkes masks, best known from V for Vendetta) when they attend protests.

While the niqāb usually shows membership of some Islamic community, its purpose is not to hinder recognition, although it falls under some anti-mask laws such as the French ban on face covering.


* Beaked masks containing herbs in the beak were worn in early modern Europe by plague doctors to try to ward off the Black Death.
* Filter mask, a piece of safety equipment.
* Full-face diving mask as part of self-contained breathing apparatus for divers and others; some let the wearer talk to others through a built-in communication device
* Respirator (gas or particulate mask), a mask worn on the face to protect the body from airborne pollutants and toxic materials, and fine particulate matter or infectious particles.
* Oxygen mask worn by high-altitude pilots, or used in medicine to deliver oxygen, anesthetic, or other gases to patients
* Welding mask to protect the welder's face and eyes from the brightness and sparks created during welding


* Balaclava, also known as a "ski mask", to protect the face against cold air.
* Baseball catcher's mask.
* Diving mask, an item of diving equipment that allows scuba divers, free-divers, and snorkelers to see clearly underwater.
* Fencing mask.
* Goaltender mask, a mask worn by an ice or field hockey goaltender to protect the head and face from injury.
* Hurling helmets were made mandatory in 2010, and have a wire mask on the front to protect the player's face.
* Kendo, a mask called Men is used in this Japanese sword-fighting martial art.
* Paintball mask.
* Visor (ice hockey).

An interesting example of a sports mask that confounds the protective function is the wrestling mask, a mask most widely used in the Mexican/Latin lucha libre style of wrestling. In modern lucha libre, masks are colourfully designed to evoke the images of animals, gods, ancient heroes, and other archetypes. The mask is considered "sacred" to some degree, placing its role closer to the ritual and performance function.


Masks are sometimes used to punish the wearer either by signalling their humiliation or causing direct suffering:

* Particularly uncomfortable types, such as an iron mask, for example the Scold's bridle, are fit as devices for humiliation, corporal punishment or torture.
* Masks were used to alienate and silence prisoners in Australian jails in the late 19th century. They were made of white cloth and covered the face, leaving only the eyes visible.


Decorative masks may be worn as part of a costume outside of ritual or ceremonial functions. This is often described as a masque, and relates closely to carnival styles. For example, attendants of a costume party will sometimes wear masks as part of their costumes.

Several artists in the 20th and 21st century, such as Isamaya Ffrench and Damselfrau, create masks as wearable art.

Wrestling masks are used most widely in Mexican and Japanese wrestling. A wrestler's mask is usually related to a wrestler's persona (for example, a wrestler known as 'The Panda' might wear a mask with a panda's facial markings). Often, wrestlers will put their masks on the line against other wrestlers' masks, titles or an opponent's hair. While in Mexico and Japan, masks are a sign of tradition, they are looked down upon in the United States and Canada.
Several bands and performers, notably members of the groups Slipknot, Mental Creepers and Gwar, and the guitarist Buckethead, wear masks when they perform on stage. Several other groups, including Kiss, Alice Cooper, and Dimmu Borgir simulate the effect with facepaint. Hollywood Undead also wears masks but often remove them mid-performance.
Leather-working, steampunk, and other methods and themes are occasionally used to create artisanal gas masks.
One user of masks in fashion is musician and fashion designer Kanye West. West has donned masks from Balenciaga and Maison Margiela, most notably on his Yeezus Tour.

In works of fiction

Masks have been used in many horror films to conceal the identities of the killer. Notable examples include Jason Voorhees of the Friday the 13th series, Jigsaw Killer from Saw, Ghostface of the Scream series, and Michael Myers of the Halloween series.

Other types

* A "buccal mask" is a mask that covers only the cheeks (hence the adjective "buccal") and mouth.
* A death mask is a mask either cast from or applied to the face of a recently deceased person.
* A "facial" (short for facial mask) is a temporary mask, not solid, used in cosmetics or as therapy for skin treatment.
* A "life mask" is a plaster cast of a face, used as a model for making a painting or sculpture.
* An animal roleplay mask is used for people to create a more animal-like image.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1895 2023-09-09 00:08:07

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1899) Tailor


A tailor is a person whose job is to make clothes, especially for men.


A tailor is a person whose occupation is making or altering garments (such as suits, jackets, and dresses) typically to fit a particular person.


A tailor is a person who makes or alters clothing, particularly in men's clothing. The Oxford English Dictionary dates the term to the thirteenth century.


Although clothing construction goes back to prehistory, there is evidence of tailor shops in Ancient Greece and Rome, as well as tailoring tools such as irons and shears. The profession of tailor in Europe became formalized in the High Middle Ages through the establishment of guilds. Tailors' guilds instituted a system of masters, journeymen, and apprentices. Guild members established rules to limit competition and establish quality standards. In 1244, members of the tailor's guild in Bologna established statutes to govern their profession and required anyone working as a tailor to join the guild.

In England, the Statute of Artificers, passed in 1563, included the profession of tailor as one of the trades that could be entered only by serving a term of apprenticeship, typically seven years.

A typical tailor shop would have a master, a foreman, several journeymen and apprentices. The apprentices, often beginning their training as young adolescents and indentured to the master by their parents (for a fee), performed menial tasks such as cleaning, managing the fires to heat the pressing-irons, running errands, and matching fabric and trims. Apprentices were also taught the "tailor's posture", to sit cross-legged on a raised board or bench while they sewed. A tailoring establishment then generally consisted of a well-appointed room in which the master would measure customers. Cutting, sewing, buttonholes, and finishing work were performed in adjoining rooms.

In England, there were many negative associations with the profession of tailoring. Tailors were often called "snips", "bodkins", "thimbles", "shreds", "stiches", and "geese" (referring to the tailor's "goose" or iron). In William Shakespeare's plays, a tailor was variously called a "thread", a "thimble", and a "rag". By reputation, tailors were generally presumed to drink to excess and to have effeminate tendencies (likely because of the view of sewing as a woman's activity). Tailors were presumed to be physically weak and to have delicate constitutions. It was commonly asserted that their diets consisted of cabbage. In comics, they were portrayed as henpecked husbands. A common saying at the time was "Nine tailors make a man".

As with other artisanal trades, tailors relied on the "house of call" or "call houses", a trade club at which they could procure workmen. Sometimes, a skilled journeyman assigned by the call house would be taken on permanently by the master. Master tailors who failed to comply with laws of wages or hours could lose access to the call houses, and journeymen whose work was reported as poor could be removed from the call book. Many tailors became virtually blind from the extensive hours of stitching by hand with only candelight to illumine the work. The call for tailoring peaked in the winter, and tailors were often unemployed for several months over the summer.

During the 18th century, the profession began to shift toward large-scale and specialized production. A hierarchy of skills resulted, with the most prestigious level reserved for those who cut the cloth. "Mere sewers" ranked below the "cutters". More respect was given to those who worked in a master's workshop than those who took in piecework in their own home. Tasks grew more specialized; by the end of the century, one individual might focus solely on collars and sleeves.

The trade was one of the first in England to exhibit labor disputes, with tailors frequently on strike against lengthy working hours, low wages, and the use of laborers outside the workshop such as women and children. The strikes generally failed; some participants were imprisoned or transported to America or Australia. The unrest eventually influenced Parliament to establish rules for wages, hours, and working conditions in the tailoring industry.[7] Tailors were one of the first trades in England to form a labor union.

The British census in 1851 identified 152,672 tailors, more than the entire railway industry at the time, and that number increased throughout the century. By then, living and working conditions of many tailors had deteriorated, but the trade was still the fourth largest of London professions. One factor was the growing availability and popularity of "slops": cheap ready-made clothing. Another was a shift from the vast majority of tailors being engaged in workshops to most working outside the shops of employers. Master tailors who relied on outside workers saved themselves the costs of lighting and heating, as well as some supplies. Rather than pay for foremen to supervise the work, masters would fine the outside workers for inferior products. Using outside workers also freed masters from the legal constraints that dictated hours and wages. Tailors who worked outside of workshops began to use their wives and family members in manufacturing garments, which increased their production to maximize their incomes. Some tailors would subcontract aspects of the work to laborers. The house of call system was abandoned. When the Statute of Artificers was repealed in 1814, it abolished the apprenticeship requirement and so tailors could no longer control admission to the trade. Tailor strikes in 1827 and 1834 were largely motivated by opposition to employing women as outworkers. Unlike other industries, in which technological advances contributed to decline of trades, the changes to the work methods in the tailoring industry that led to its decline had occurred several decades before the development of the mechanical sewing machine.


Tailoring men's jackets by adding underlayers of padding became fashionable in Europe by the 14th century. Over the years, additional areas were padded to provide an understructure that helped the garment lie neatly on the body. By the 19th century, well-tailored garments were carefully fit to the wearer with a more subtly shaped understructure. Even with the advent of modern machines, nearly 75 percent of a custom-tailored suit's stitching is still done by hand.

The earliest extant work on cutting by tailors is from Spain in 1580. Juan de Alcega, a Spanish tailor in the 16th century, published Libro de Geometría, practica, y traça (Book on Geometry, Practice, and Pattern) which documented methods of laying out patterns to achieve the most economical use of the fabric. Alcega illustrated 163 patterns to scale in 23 categories of men's and women's garments.

Master tailors used proprietary methods for creating their clothing patterns. Up until approximately 1790, patterns to be used for cutting were considered trade secrets to be exclusively owned by the masters. By the late 18th century, publications that not only printed patterns but also gave directions for cutting and layout were widely available.

In addition to patterns and templates, some master tailors and cutters use the rock of eye method of cutting: which is a freehand way of drafting a pattern by trusting your eye and experience rather than focusing on numbers. Instead of using pencil to draft the pattern, the rock of eye typically involves chalk to mark.

Regional styles

Just as there are various methods of tailoring, there are also styles that differ regionally. This is due to different climates and cultures in the world, causing "house style" cuts of the trade.

British cut

The silhouette of a British cut suit is influenced by military tailoring, with a defined waist and shoulders. The target image is that of an upper-class gentleman.

The British cut of tailoring can be defined by various ways of inner construction. Since the United Kingdom has a cooler climate than (for example) the Mediterranean, the cut of the British is more heavy, with a more military influence. This style of canvassing has 3 layers, a wool or camel-hair canvas for the body, a horsehair chest piece for the breast area, and a flannel domette for a more masculine pronounced bulk. The shoulders of the British are more padded. The fabrics used by the British are in the range of 9-13 oz due to the colder climate. This style of cut can be credited to Henry Poole & Co, and H. Huntsman & Sons. The British are also credited in creating their ever-so-popular trademark, the Drape cut, credited to Frederick Scholte who trained the founders of Anderson & Sheppard.

Italian cut

An Italian cut suit offers a flattering shape with soft tailoring, aiming for the most attractive appearance for the wearer. A suit jacket in northern Italy will usually have a square shoulder, while in southern Italy, the preference is for a more natural shoulder.

Like the British cut, the Italian cut is defined by its inner construction. Since Italy lies in southern Europe and has a warm climate, the Italian tailors developed a cut that was light and cooler to coincide with the conditions. What they developed is called the Italian/European cut. This cut is more light, with fabrics ranging from 7-9 oz. This way of doing canvas has a range of 1-2 layers, a linen body canvas, and a light horsehair canvas. The Italian shoulder is more natural, and sometimes has a “shirt sleeve” with a roping head. The cut is also slimmer than the British, with a more casual setting. The tailors credited with these cuts are Brioni and Rubinacci.

Bespoke suits created by an Italian tailor are called su misura. The average cost of a su misura suit is between €1,700 and €3,000, although one might cost more than €5,000 from the finest tailoring houses. A master tailor can create a suit in approximately 40 hours. The number of tailors in Italy decreases at a rate of 8 percent annually, with fewer than 750 tailors as of 2016.

American cut

The American cut of tailoring is a mix of the Italian and the British ways. The American cut is more baggy and full, with a natural shoulder that is lightly padded. American tailoring usually involves doing light canvas, where only the canvas and the flannel domette are used. The most well-known cut developed by the Americans is the Ivy League cut. The tailors credited with this cut remain anonymous.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1896 2023-09-10 00:08:16

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1900) Museum


A museum is a not-for-profit, permanent institution in the service of society that researches, collects, conserves, interprets and exhibits tangible and intangible heritage. Open to the public, accessible and inclusive, museums foster diversity and sustainability. They operate and communicate ethically, professionally and with the participation of communities, offering varied experiences for education, enjoyment, reflection and knowledge sharing.


A museum is a community service that displays and preserves objects of significance. Many museums have exhibitions of these objects in public display, and some have private collections that are used by researchers and specialists. Compared to a library, a museum hosts a much wider ranges of objects and usually focus around a specific theme such as the arts, science, natural history, local history, and other topics. Public museums that host exhibitions and interactive demonstrations are often considered to be tourist attractions, and many museums attract large numbers of visitors from outside their host country, with the most visited museums in the world regularly attracting millions of visitors annually.

Since the establishment of the earliest known museum in ancient times, museums have been associated with academia and the preservation of rare items. Museums originated as private collections of interesting items, and only much later did the emphasis on educating the public take root.


The English "museum" comes from the Latin word, and is pluralized as "museums" (or rarely, "musea"). It is originally from the Ancient Greek Μουσεῖον (Mouseion), which denotes a place or temple dedicated to the muses (the patron divinities in Greek mythology of the arts), and hence was a building set apart for study and the arts, especially the Musaeum (institute) for philosophy and research at Alexandria, built under Ptolemy I Soter about 280 BC.


The purpose of modern museums is to collect, preserve, interpret, and display objects of artistic, cultural, or scientific significance for the study and education of the public. To city leaders, an active museum community can be seen as a gauge of the cultural or economic health of a city, and a way to increase the sophistication of its inhabitants. To museum professionals, a museum might be seen as a way to educate the public about the museum's mission, such as civil rights or environmentalism. Museums are, above all, storehouses of knowledge. In 1829, James Smithson's bequest funding the Smithsonian Institution stated that he wanted to establish an institution "for the increase and diffusion of knowledge".

Museums of natural history in the late 19th century exemplified the scientific desire for the classification of life and for interpretations of the world. Gathering all examples for each field of knowledge for research and display was the purpose. As American colleges grew in the 19th century, they developed their own natural history collections for the use of their students. By the last quarter of the 19th century, scientific research in universities was shifting toward biological research on a cellular level, and cutting-edge research moved from museums to university laboratories. While many large museums, such as the Smithsonian Institution, are still respected as research centers, research is no longer a main purpose of most museums. While there is an ongoing debate about the purposes of interpretation of a museum's collection, there has been a consistent mission to protect and preserve cultural artifacts for future generations. Much care, expertise, and expense is invested in preservation efforts to retard decomposition in aging documents, artifacts, artworks, and buildings. All museums display objects that are important to a culture. As historian Steven Conn writes, "To see the thing itself, with one's own eyes and in a public place, surrounded by other people having some version of the same experience, can be enchanting."

Museum purposes vary from institution to institution. Some favor education over conservation, or vice versa. For example, in the 1970s, the Canada Science and Technology Museum favored education over the preservation of their objects. They displayed objects as well as their functions. One exhibit featured a historical printing press that a staff member used for visitors to create museum memorabilia. Some museums seek to reach a wide audience, such as a national or state museum, while others have specific audiences, like the LDS Church History Museum or local history organizations. Generally speaking, museums collect objects of significance that comply with their mission statement for conservation and display. Apart from questions of provenance and conservation, museums take into consideration the former use and status of an object. Religious or holy objects, for instance, are handled according to cultural rules. Jewish objects that contain the name of God may not be discarded, but need to be buried.

Although most museums do not allow physical contact with the associated artifacts, there are some that are interactive and encourage a more hands-on approach. In 2009, Hampton Court Palace, a palace of Henry VIII, in England opened the council room to the general public to create an interactive environment for visitors. Rather than allowing visitors to handle 500-year-old objects, however, the museum created replicas, as well as replica costumes. The daily activities, historic clothing, and even temperature changes immerse the visitor in an impression of what Tudor life may have been.


Major professional organizations from around the world offer some definitions as to what constitutes a museum, and their purpose. Common themes in all the definitions are public good and the care, preservation, and interpretation of collections.

The International Council of Museums' current definition of a museum (adopted in 2022): "A museum is a not-for-profit, permanent institution in the service of society that researches, collects, conserves, interprets and exhibits tangible and intangible heritage. Open to the public, accessible and inclusive, museums foster diversity and sustainability. They operate and communicate ethically, professionally and with the participation of communities, offering varied experiences for education, enjoyment, reflection and knowledge sharing."

The Canadian Museums Association's definition: "A museum is a non-profit, permanent establishment, that does not exist primarily for the purpose of conducting temporary exhibitions and that is open to the public during regular hours and administered in the public interest for the purpose of conserving, preserving, studying, interpreting, assembling and exhibiting to the public for the instruction and enjoyment of the public, objects and specimens or educational and cultural value including artistic, scientific, historical and technological material."

The United Kingdom's Museums Association's definition: "Museums enable people to explore collections for inspiration, learning and enjoyment. They are institutions that collect, safeguard and make accessible artifacts and specimens, which they hold in trust for society."

While the American Alliance of Museums does not have such a definition, their list of accreditation criteria to participate in their Accreditation Program states a museum must: "Be a legally organized nonprofit institution or part of a nonprofit organization or government entity; Be essentially educational in nature; Have a formally stated and approved mission; Use and interpret objects or a site for the public presentation of regularly scheduled programs and exhibits; Have a formal and appropriate program of documentation, care, and use of collections or objects; Carry out the above functions primarily at a physical facility or site; Have been open to the public for at least two years; Be open to the public at least 1,000 hours a year; Have accessioned 80 percent of its permanent collection; Have at least one paid professional staff with museum knowledge and experience; Have a full-time director to whom authority is delegated for day-to-day operations; Have the financial resources sufficient to operate effectively; Demonstrate that it meets the Core Standards for Museums; Successfully complete the Core Documents Verification Program".

Additionally, there is a legal definition of museum in United States legislation authorizing the establishment of the Institute of Museum and Library Services: "Museum means a public, tribal, or private nonprofit institution which is organized on a permanent basis for essentially educational, cultural heritage, or aesthetic purposes and which, using a professional staff: Owns or uses tangible objects, either animate or inanimate; Cares for these objects; and Exhibits them to the general public on a regular basis." (Museum Services Act 1976).


A museum is an institution dedicated to preserving and interpreting the primary tangible evidence of humankind and the environment. In its preserving of this primary evidence, the museum differs markedly from the library, with which it has often been compared, for the items housed in a museum are mainly unique and constitute the raw material of study and research. In many cases they are removed in time, place, and circumstance from their original context, and they communicate directly to the viewer in a way not possible through other media. Museums have been founded for a variety of purposes: to serve as recreational facilities, scholarly venues, or educational resources; to contribute to the quality of life of the areas where they are situated; to attract tourism to a region; to promote civic pride or nationalistic endeavour; or even to transmit overtly ideological concepts. Given such a variety of purposes, museums reveal remarkable diversity in form, content, and even function. Yet, despite such diversity, they are bound by a common goal: the preservation and interpretation of some material aspect of society’s cultural consciousness.


As institutions that preserve and interpret the material evidence of humankind, human activity, and the natural world, museums have a long and varied history, springing from what may be an innate human desire to collect and interpret and having discernible origins in large collections built up by individuals and groups before the modern era.


From mouseion to museum

The word museum has classical origins. In its Greek form, mouseion, it meant “seat of the Muses” and designated a philosophical institution or a place of contemplation. Use of the Latin derivation, museum, appears to have been restricted in Roman times mainly to places of philosophical discussion. Thus, the great Museum at Alexandria, founded by Ptolemy I Soter early in the 3rd century BCE, with its college of scholars and its famous library, was more a prototype university than an institution to preserve and interpret material aspects of one’s heritage. The word museum was revived in 15th-century Europe to describe the collection of Lorenzo de’ Medici in Florence, but the term conveyed the concept of comprehensiveness rather than denoting a building. By the 17th century, museum was being used in Europe to describe collections of curiosities. Ole Worm’s collection in Copenhagen was so called, and in England visitors to John Tradescant’s collection in Lambeth (now a London borough) called the array there a museum; the catalog of this collection, published in 1656, was titled Musaeum Tradescantianum. In 1675 the collection, having become the property of Elias Ashmole, was transferred to the University of Oxford. A building was constructed to receive it, and this, soon after being opened to the public in 1683, became known as the Ashmolean Museum. Although there is some ambivalence in the use of museum in the legislation, drafted in 1753, founding the British Museum, nevertheless the idea of an institution called a museum and established to preserve and display a collection to the public was well established in the 18th century. Indeed, Denis Diderot outlined a detailed scheme for a national museum for France in the ninth volume of his Encyclopédie, published in 1765.

Use of the word museum during the 19th and most of the 20th century denoted a building housing cultural material to which the public had access. Later, as museums continued to respond to the societies that created them, the emphasis on the building itself became less dominant. Open-air museums, comprising a series of buildings preserved as objects, and ecomuseums, involving the interpretation of all aspects of an outdoor environment, provide examples of this. In addition, so-called virtual museums exist in electronic form on the Internet. Although virtual museums provide interesting opportunities for and bring certain benefits to existing museums, they remain dependent upon the collection, preservation, and interpretation of material things by the real museum.

Museology and museography

Along with the identification of a clear role for museums in society, there gradually developed a body of theory the study of which is known as museology. For many reasons, the development of this theory was not rapid. Museum personnel were nearly always experienced and trained in a discipline related to a particular collection, and therefore they had little understanding of the museum as a whole, its operation, and its role in society. As a result, the practical aspects of museum work—for example, conservation and display—were achieved through borrowing from other disciplines and other techniques, whether or not they particularly met the requirements of the museum and its public.

Thus, not only was the development of theory slow, but the theory’s practical applications—known as museography—fell far short of expectations. Museums suffered from a conflict of purpose, with a resulting lack of clear identity. Further, the apprenticeship method of training for museum work gave little opportunity for the introduction of new ideas. This situation prevailed until other organizations began to coordinate, develop, and promote museums. In some cases, museums came to be organized partly or totally as a government service; in others, professional associations were formed, while an added impetus arose where universities and colleges took on responsibilities for museum training and research.

The words derived from museum have a respectable, if confused, history. Emanuel Mendes da Costa, in his Elements of Conchology, published in 1776, referred to “museographists,” and a Zeitschrift für Museologie und Antiquitätenkunde (“Journal of Museology and Antique Studies”) appeared in Dresden in 1881. But the terms museology and museography have been used indiscriminately in the literature, and there is a tendency, particularly in English-speaking countries, to use museology or museum studies to embrace both the theory and practice of museums.

Museum activities:


Acquisition policies

Relatively few museums have been established with the specific goal of forming a collection; instead, most have been created to receive an existing collection. With the existing collection as its base, the museum then traditionally works to fill in gaps in the collection or extend its activities into other, usually related, fields. For this reason, many museums have heterogeneous collections, at best accumulated under an “encyclopaedic” philosophy (which has rarely been successful unless major resources were available to achieve it) and at worst continuing a “cabinet of curiosities” approach (which may amuse and entertain the clientele but does little to engender scholarship or research). Often the collections made depended on the expertise or whim of the curator and were sure to change when that curator was succeeded by someone with different interests. This method has produced some outstanding special collections, but these resulted from circumstance rather than long-term planning.

Explicit collection policies are now more common. Indeed, where national codes of practice exist, a strong recommendation is normally to be found on the need for a clear statement of collecting activity. This arose for a number of reasons. Not only should a public institution’s policies be available for scrutiny, but the cost of maintaining collections of ever-increasing size must be justified, a factor highlighted at times of economic pressure. Further, although a museum may have arisen from circumstance, an assessment of its available resources, the clientele it attracts or intends to attract, and the role it can serve in society generally must be matched against its primary resource, its collections.


Every museum is responsible for ensuring the legality of its acquisitions. Laws regulating collection vary from country to country, but, whether or not a state has enacted its own legislation or ratified relevant international conventions, museum staff are expected to conform to generally recognized professional codes of ethics. Most regulation of collecting activity embodies principles established in the 1954 Convention for the Protection of Cultural Property in the Event of Armed Conflict and the 1970 Convention on the Means of Prohibiting and Preventing the Illicit Import, Export, and Transfer of Ownership of Cultural Property, both approved by member states of UNESCO. However, a number of countries involved in international trade found it difficult to ratify the 1970 convention, and certain difficulties arose over the definition of cultural property. The 1995 Unidroit Convention on Stolen or Illegally Exported Cultural Objects was intended to resolve these issues. Similar conventions exist on the regional level as well: for instance, in 1976 the Organization of American States adopted the San Salvador Convention on the Protection of the Archaeological, Historical, and Artistic Heritage of the American Nations, and, with a similar purpose in mind, in 1992 the Council of Europe issued a revised European Convention on the Protection of the Archaeological Heritage.

Given the number and variety of legal regulations and professional codes, it is unlikely that a museum with clearly stated academic objectives will acquire illicit material. Indeed, methods of collection reflect the fact that a museum is concerned not only with collections per se but also with the information inherent in or associated with them. Where applicable, direct acquisition through fieldwork is much preferred. This involves collecting material through archaeological excavation, ethnological expeditions, or natural science fieldwork, and the collecting either is undertaken by the staff of the museum or is sponsored by it. Indirect acquisition is handled through purchases, gifts, bequests, and loans of objects. Where objects are thus acquired, art museums often stipulate that staff must assess a number of qualifications, notably the provenance (a record of the object’s ownership) of each piece, and that a committee must approve the acquisition.

Protection of cultural property

Conventions such as those cited above reflect the fact that the collecting activities of the industrialized world are markedly different from those available to the developing nations. In some instances the significant cultural property of entire nations has been dispersed to private collections and museums in different parts of the world, leaving the developing museums to rely on casts and replicas to convey the area’s cultural achievements. The international community has had only limited success in encouraging the return, through exchange or loan, of such material to its country of origin.

The true significance of cultural property, collectively the universal heritage of humankind, places on museums a considerable responsibility. The acceptance of objects or collections into their care implies a permanence not associated with the acceptance of other types of property. Some museum legislation acknowledges this, declaring such collections inalienable. The disposal of museum collections in part or in full therefore normally only occurs in cases where items no longer serve a useful scholarly or interpretative purpose. The case for deaccessioning, as it is known, can only otherwise have any validity where it is done to correct the imbalances of earlier indiscriminate collecting, and in that case the material concerned should first be made available to other suitable museums before disposal. The Baltimore Museum of Art, for example, sold several pieces in the 2010s to acquire work by previously underrepresented populations. During this time, however, the Berkshire Museum in Pittsfield, Massachusetts, caused controversy when it announced that it would use proceeds from the sale of dozens of artworks not for the care of its collection or for acquisition purposes, as recommended by the American Alliance of Museums, but for the operation of the institution.


A museum’s prime responsibility must be to maintain its collections and to do everything possible to delay the natural laws of deterioration. The acquisition of an item almost certainly brings it into a new and potentially alien environment. Material that has been recovered from the ground through archaeological excavation may need immediate treatment to stabilize it. Many of the materials from which objects are made are inherently unstable and undergo chemical or structural change as they age. A new or shifting environment can accelerate these changes, and temperature, light, humidity, and human and other biological factors all need to be controlled. In addition, conservation involves the treatment and, where feasible and acceptable, the restoration of objects as nearly as possible to their former condition.

Most large museums have their own laboratories where preservation and restoration work is carried out, and some take on projects for other museums as well. In some cases, as at the British Museum, a separate department of scientific research supports the museum’s academic and conservation work, providing advanced scientific equipment for the analysis, dating, and identification of materials. Some museums are served by independent conservation laboratories, an example of which is the Canadian Conservation Institute in Ottawa, which uses a fleet of mobile laboratories to attend to museum collections in many parts of the country.


Documentation is a significant function of any museum, whether it holds only a few hundred objects or many millions of items. Quite apart from the need for records to maintain adequate control of its collections, a museum’s documentation system provides an indispensable record of the information associated with the objects for research. The documentation system also may include records to facilitate the museum’s interpretative and other work.

The form of a museum’s documentation system may vary considerably, but to meet these requirements it should provide the fullest possible information about each item and its history. There are no generally accepted classification schemes for museum objects, although certain subjects have developed schemes with numeric or alphanumeric notations to facilitate the ordering and retrieval of information. For the natural sciences, taxonomic names are normally used.

A number of museums have developed computerized documentation systems, some online but others relying on machine-generated indexes, periodically updated, to meet most of their information requirements. The advantages of computerized documentation have been exploited in a number of ways—for instance, in exchanging data between museums to facilitate study and research or in making collection information available for public use in the museum gallery or over the Internet.


Because they hold the primary material evidence for a number of subjects concerned with an understanding of humankind and the environment, museums clearly have an important role in research. A museum’s research program is related to its objectives as an institution. A program may be concerned directly with the public services provided, in preparing exhibitions, catalogs, and other publications, or with promoting a better understanding of the discipline or region that it serves. In large museums, and in university museums in particular, pure and applied research may be of national or international significance and may be associated with fieldwork or study visits. Active research and publication on a given topic, apart from contributing to the academic standing of the institution, may attract further collections relevant to the topic.

Many museums provide facilities, apart from those used by casual visitors, for researchers to study collections and associated documentation. Such facilities may include study rooms with a supporting library and equipment to assist in the examination of collections. Certain museums have accommodations for visiting foreign scholars; this feature is particularly helpful at site museums that are difficult to reach.


Many museums have abandoned the traditional view of exhibition, by which storage and display are ends in themselves, in favour of an approach that enhances the setting of the object or collection. To this end museums use the expertise of a number of specialists—designers, educators, sociologists, and interpreters as well as curators—to improve communication through objects. The result has been a remarkable transformation in the presentation of museum displays. Far greater use is made of colour and light (within the bounds prescribed by conservation requirements), in the way material is interpreted through a variety of mediums (sound, video, interaction between visitor and exhibit, virtual reality, as well as more traditional methods), and in the provision of a more relaxing environment in which to enjoy the exhibits. A result of museums’ increased awareness of the needs of their visitors has been a considerable increase in museum attendance.

As the museum’s cultural role has developed, so its exhibition work has diversified. Large international exhibitions have been organized by cooperating nations and have been shown in the major museums of the participating countries. Exhibitions organized for national circulation are also increasingly common. Museums concerned with a particular region have arranged topical exhibitions to tour the area, and, in places without suitable premises for display or in sparsely populated areas, exhibitions have toured in specially adapted buses or trains. Some countries have developed multipurpose cultural centres, and collaboration with museums has resulted in exhibition programs successfully reaching a wide audience.

Interest in the historic and natural environment globally has involved museums in the preservation and interpretation of sites, monuments, and landscapes (as in the Slave House museum at Gorée Island, Senegal). Here the conflict inherent in imposing an interpretive medium into a natural or historical context has to be resolved. In its simplest form, interpretation may be conveyed through nature or history trails in which information is provided in written or recorded form. With a historic property there are also opportunities to reenact events associated with the property, such as period battle scenes and banquets, to demonstrate industrial or craft techniques, or to use theatre and son et lumière performances to interpret the site.

Educational services

The contribution that museums can make to education is widely acknowledged. The majority of their clientele learn by looking at exhibitions and displays. There has been, however, a long association with schools, and many museums provide services specifically designed to meet schools’ needs. Services include facilities for use both in the museum and at the school, many of which are administered by separate departments of museum education employing teachers for the purpose.

Special rooms equipped for teaching and for handling specimens are provided in many museums. By allowing the study and handling of objects from its collections, the museum can give substance and form to the bare facts of art, history, and science. Some museums build special collections for this purpose. Teaching may be undertaken by the museum’s educational staff or, more often, by the schoolteacher, who will have been advised and instructed by the staff. For advanced studies, particularly in subjects like archaeology and geology, the availability of museum collections can be indispensable.

Although opinion differs as to the value of school loan collections, many museums do provide small exhibit cases or kits that may be borrowed by the school for a limited period for classroom teaching. Unlike libraries, museums are not able to provide extensive loan services (which would conflict with their prime purpose), but, for rural schools unable to visit the museum, such a facility, albeit limited, meets a need. In some areas museums include the larger community schools within their traveling exhibition schedules.

As a better-educated adult population with increased leisure time seeks purposeful outlets, museums are well placed to provide activities. Many museums offer lectures, courses, demonstrations, field excursions, and extensive travel-abroad opportunities.

Information services

A museum acts as an information centre for its community. In addition to its displays and exhibitions, its data banks and publications, it has a staff of specialists, who in most cases are available by appointment to provide information on request.

Museum publications may be educational or cultural or may be designed for a popular market. They may take the form of periodicals, handbooks, catalogs, research papers, or general guides to aspects of the museum and are an important medium for disseminating information to the lay public and scholar alike; such information and products are now commonly available via the museum’s Web site. Many museums also offer an opinion on items brought to them for identification. This can be of value to both the inquirer and the museum because it provides an awareness of local discoveries and holdings that aids the museum’s efforts to build up a picture of its area of responsibility. At the same time it provides an informed opinion as a public service. Museums rarely provide valuations, however, and some, to avoid conflicts of interest, decline to have any connection with the antiques trade.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1897 2023-09-11 00:09:18

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1901) Planetarium


A planetarium is a theatre devoted to popular education and entertainment in astronomy and related fields, especially space science, and traditionally constructed with a hemispheric domed ceiling that is used as a screen onto which images of stars, planets, and other celestial objects are projected. The term planetarium may also refer to an institution in which such a theatre functions as the principal teaching arrangement or to the specialized projector employed. Planetarium is applied in yet another sense to describe computer software or Internet sites that allow the user to simulate views of the night sky and various celestial phenomena.

Permanent planetarium installations vary greatly. Those within a large supporting institution may coexist with extensive exhibit space and museum collections and have sizable professional and support staffs. Their projection theatres can be 25 metres (82 feet) or more in diameter and have capacities in excess of 600 persons. On the other hand, community or local college planetariums may accommodate only small groups of people. In a separate class are portable planetariums comprising inflatable domes and lightweight projectors that can be set up at schools and can hold several dozen students at a time.

At the heart of every planetarium theatre is the projection instrument. The first modern electromechanical planetarium projector was built by the German optical firm Carl Zeiss in 1923 for the new Deutsches Museum in Munich. Current descendants of these instruments are technically complex, computer-controlled combinations of lamps, lenses, fibre optics, and motor drives designed to place the planets, Sun, and Moon in their correct locations among the stars for thousands of years past and future and to reproduce their motions through the sky, typically as seen from a selected latitude on Earth. The instruments also can add such details as horizon scenes, the Milky Way, nebulae, comets, meteors, and various reference lines and scales used for teaching descriptive astronomy and celestial navigation.

Increasingly, institution-based planetariums are complementing or replacing electromechanical projectors with other technologies, including all-digital projector systems equipped with fish-eye lenses and laser projection systems that scan their images on the screen with colour-controlled laser beams. Digital and laser systems allow a seamless blending of sky images, photos, artwork, video, and computer-generated animations. They also can simulate accurate views from any perspective in space and take viewers on virtual flights through and beyond the solar system and into interstellar and intergalactic space. Variations in screen configuration and seating arrangements also are becoming common, ranging from the traditional horizontal domed screen and concentric seating around a central projector to tilted or distorted domes or giant wraparound screens and auditorium-style seating.

In a typical planetarium theatre, programs—commonly called sky shows—are offered to the public on a regular schedule. Show themes may focus on straightforward astronomical and space topics or take up related issues such as the cosmologies of ancient cultures, the extinction of the dinosaurs, or the future of life on Earth. The trend, especially for large audiences and multiple daily shows, is toward total computer automation of the program, combining visual display, cued music and sound effects, and prerecorded narration. Large planetariums with technologically advanced multimedia installations often supplement their science programs with shows featuring pure entertainment based on light, video, and music. In significant ways, in both technology and public program content, the distinction has lessened between planetarium theatres and other giant-screen “total immersion” entertainment centres.

When the Deutsches Museum’s planetarium, featuring the Zeiss projector, was publicly unveiled in 1923 (two years before the museum’s formal opening), it was described as a “schoolroom under the vault of the heavens.” Special educational sky shows for schoolchildren remain an essential part of the program in most installations; astronomy lectures are given to college classes; and the facilities are commonly used for courses or lectures in adult continuing-education programs.

The term planetarium was originally used to describe a type of mechanical model designed to portray the orbital motions of the planets and their moons. Made for teaching and exhibition, such tabletop devices consisted of small globes, representing the Sun and planets, that were mounted on wire rods supported and geared at a central pedestal. Many included the major moons known at the time of construction. Also called orreries (after the English sponsor of one built in 1712), they could be quite elaborate and accurate.

Additional Information

A planetarium (pl: planetariums or planetaria) is a theatre built primarily for presenting educational and entertaining shows about astronomy and the night sky, or for training in celestial navigation.

A dominant feature of most planetariums is the large dome-shaped projection screen onto which scenes of stars, planets, and other celestial objects can be made to appear and move realistically to simulate their motion. The projection can be created in various ways, such as a star ball, slide projector, video, fulldome projector systems, and lasers. Typical systems can be set to simulate the sky at any point in time, past or present, and often to depict the night sky as it would appear from any point of latitude on Earth.

Planetaria range in size from the 37 meter dome in St. Petersburg, Russia (called “Planetarium No 1”) to three-meter inflatable portable domes where attendees sit on the floor. The largest planetarium in the Western Hemisphere is the Jennifer Chalsty Planetarium at Liberty Science Center in New Jersey, its dome measuring 27 meters in diameter. The Birla Planetarium in Kolkata, India is the largest by seating capacity, having 630 seats. In North America, the Hayden Planetarium at the American Museum of Natural History in New York City has the greatest number of seats, at 423.

The term planetarium is sometimes used generically to describe other devices which illustrate the Solar System, such as a computer simulation or an orrery. Planetarium software refers to a software application that renders a three-dimensional image of the sky onto a two-dimensional computer screen, or in a virtual reality headset for a 3D representation. The term planetarian is used to describe a member of the professional staff of a planetarium.



The ancient Greek polymath Archimedes is attributed with creating a primitive planetarium device that could predict the movements of the Sun and the Moon and the planets. The discovery of the Antikythera mechanism proved that such devices already existed during antiquity, though likely after Archimedes' lifetime. Campanus of Novara described a planetary equatorium in his Theorica Planetarum, and included instructions on how to build one. The Globe of Gottorf built around 1650 had constellations painted on the inside. These devices would today usually be referred to as orreries (named for the Earl of Orrery). In fact, many planetariums today have projection orreries, which project onto the dome the Solar System (including the Sun and planets up to Saturn) in their regular orbital paths.

In 1229, following the conclusion of the Fifth Crusade, Holy Roman Emperor Frederick II of Hohenstaufen brought back a tent with scattered holes representing stars or planets. The device was operated internally with a spinnable table that rotated the tent.

The small size of typical 18th century orreries limited their impact, and towards the end of that century a number of educators attempted to create a larger sized version. The efforts of Adam Walker (1730–1821) and his sons are noteworthy in their attempts to fuse theatrical illusions with education. Walker's Eidouranion was the heart of his public lectures or theatrical presentations. Walker's son describes this "Elaborate Machine" as "twenty feet high, and twenty-seven in diameter: it stands vertically before the spectators, and its globes are so large, that they are distinctly seen in the most distant parts of the Theatre. Every Planet and Satellite seems suspended in space, without any support; performing their annual and diurnal revolutions without any apparent cause". Other lecturers promoted their own devices: R E Lloyd advertised his Dioastrodoxon, or Grand Transparent Orrery, and by 1825 William Kitchener was offering his Ouranologia, which was 42 feet (13 m) in diameter. These devices most probably sacrificed astronomical accuracy for crowd-pleasing spectacle and sensational and awe-provoking imagery.

The oldest, still working planetarium can be found in the Dutch town Franeker. It was built by Eise Eisinga (1744–1828) in the living room of his house. It took Eisinga seven years to build his planetarium, which was completed in 1781.

In 1905 Oskar von Miller (1855–1934) of the Deutsches Museum in Munich commissioned updated versions of a geared orrery and planetarium from M Sendtner, and later worked with Franz Meyer, chief engineer at the Carl Zeiss optical works in Jena, on the largest mechanical planetarium ever constructed, capable of displaying both heliocentric and geocentric motion. This was displayed at the Deutsches Museum in 1924, construction work having been interrupted by the war. The planets travelled along overhead rails, powered by electric motors: the orbit of Saturn was 11.25 m in diameter. 180 stars were projected onto the wall by electric bulbs.

While this was being constructed, von Miller was also working at the Zeiss factory with German astronomer Max Wolf, director of the Landessternwarte Heidelberg-Königstuhl observatory of the University of Heidelberg, on a new and novel design, inspired by Wallace W. Atwood's work at the Chicago Academy of Sciences and by the ideas of Walther Bauersfeld and Rudolf Straubel at Zeiss. The result was a planetarium design which would generate all the necessary movements of the stars and planets inside the optical projector, and would be mounted centrally in a room, projecting images onto the white surface of a hemisphere. In August 1923, the first (Model I) Zeiss planetarium projected images of the night sky onto the white plaster lining of a 16 m hemispherical concrete dome, erected on the roof of the Zeiss works. The first official public showing was at the Deutsches Museum in Munich on October 21, 1923.

After World War II

Opened in 1955, the Surveyor Germán Barbato Municipal Planetarium in Montevideo, Uruguay, is the oldest planetarium in Latin America and the southern hemisphere.

When Germany was divided into East and West Germany after the war, the Zeiss firm was also split. Part remained in its traditional headquarters at Jena, in East Germany, and part migrated to West Germany. The designer of the first planetariums for Zeiss, Walther Bauersfeld, also migrated to West Germany with the other members of the Zeiss management team. There he remained on the Zeiss West management team until his death in 1959.

The West German firm resumed making large planetariums in 1954, and the East German firm started making small planetariums a few years later. Meanwhile, the lack of planetarium manufacturers had led to several attempts at construction of unique models, such as one built by the California Academy of Sciences in Golden Gate Park, San Francisco, which operated 1952–2003. The Korkosz brothers built a large projector for the Boston Museum of Science, which was unique in being the first (and for a very long time only) planetarium to project the planet Uranus. Most planetariums ignore Uranus as being at best marginally visible to the naked eye.

A great boost to the popularity of the planetarium worldwide was provided by the Space Race of the 1950s and 60s when fears that the United States might miss out on the opportunities of the new frontier in space stimulated a massive program to install over 1,200 planetariums in U.S. high schools.

Early Spitz star projector

Armand Spitz recognized that there was a viable market for small inexpensive planetaria. His first model, the Spitz A, was designed to project stars from a dodecahedron, thus reducing machining expenses in creating a globe. Planets were not mechanized, but could be shifted by hand. Several models followed with various upgraded capabilities, until the A3P, which projected well over a thousand stars, had motorized motions for latitude change, daily motion, and annual motion for Sun, Moon (including phases), and planets. This model was installed in hundreds of high schools, colleges, and even small museums from 1964 to the 1980s.

Japan entered the planetarium manufacturing business in the 1960s, with Goto and Minolta both successfully marketing a number of different models. Goto was particularly successful when the Japanese Ministry of Education put one of their smallest models, the E-3 or E-5 (the numbers refer to the metric diameter of the dome) in every elementary school in Japan.

Phillip Stern, as former lecturer at New York City's Hayden Planetarium, had the idea of creating a small planetarium which could be programmed. His Apollo model was introduced in 1967 with a plastic program board, recorded lecture, and film strip. Unable to pay for this himself, Stern became the head of the planetarium division of Viewlex, a mid-size audio-visual firm on Long Island. About thirty canned programs were created for various grade levels and the public, while operators could create their own or run the planetarium live. Purchasers of the Apollo were given their choice of two canned shows, and could purchase more. A few hundred were sold, but in the late 1970s Viewlex went bankrupt for reasons unrelated to the planetarium business.

During the 1970s, the OmniMax movie system (now known as IMAX Dome) was conceived to operate on planetarium screens. More recently, some planetariums have re-branded themselves as dome theaters, with broader offerings including wide-screen or "wraparound" films, fulldome video, and laser shows that combine music with laser-drawn patterns.

Learning Technologies Inc. in Massachusetts offered the first easily portable planetarium in 1977. Philip Sadler designed this patented system which projected stars, constellation figures from many mythologies, celestial coordinate systems, and much else, from removable cylinders (Viewlex and others followed with their own portable versions).

When Germany reunified in 1989, the two Zeiss firms did likewise, and expanded their offerings to cover many different size domes.

Computerized planetaria

In 1983, Evans & Sutherland installed the first digital planetarium projector displaying computer graphics (Hansen planetarium, Salt Lake City, Utah)—the Digistar I projector used a vector graphics system to display starfields as well as line art. This gives the operator great flexibility in showing not only the modern night sky as visible from Earth, but as visible from points far distant in space and time. The newest generations of planetarium projectors, beginning with Digistar 3, offer fulldome video technology. This allows for the projection of any image.


Planetarium domes range in size from 3 to 35 m in diameter, accommodating from 1 to 500 people. They can be permanent or portable, depending on the application.

* Portable inflatable domes can be inflated in minutes. Such domes are often used for touring planetariums visiting, for example, schools and community centres.

* Temporary structures using glass-reinforced plastic (GRP) segments bolted together and mounted on a frame are possible. As they may take some hours to construct, they are more suitable for applications such as exhibition stands, where a dome will stay up for a period of at least several days.

* Negative-pressure inflated domes are suitable in some semi-permanent situations. They use a fan to extract air from behind the dome surface, allowing atmospheric pressure to push it into the correct shape.

* Smaller permanent domes are frequently constructed from glass reinforced plastic. This is inexpensive but, as the projection surface reflects sound as well as light, the acoustics inside this type of dome can detract from its utility. Such a solid dome also presents issues connected with heating and ventilation in a large-audience planetarium, as air cannot pass through it.

* Older planetarium domes were built using traditional construction materials and surfaced with plaster. This method is relatively expensive and suffers the same acoustic and ventilation issues as GRP.

* Most modern domes are built from thin aluminium sections with ribs providing a supporting structure behind. The use of aluminium makes it easy to perforate the dome with thousands of tiny holes. This reduces the reflectivity of sound back to the audience (providing better acoustic characteristics), lets a sound system project through the dome from behind (offering sound that seems to come from appropriate directions related to a show), and allows air circulation through the projection surface for climate control.

The realism of the viewing experience in a planetarium depends significantly on the dynamic range of the image, i.e., the contrast between dark and light. This can be a challenge in any domed projection environment, because a bright image projected on one side of the dome will tend to reflect light across to the opposite side, "lifting" the black level there and so making the whole image look less realistic. Since traditional planetarium shows consisted mainly of small points of light (i.e., stars) on a black background, this was not a significant issue, but it became an issue as digital projection systems started to fill large portions of the dome with bright objects (e.g., large images of the sun in context). For this reason, modern planetarium domes are often not painted white but rather a mid grey colour, reducing reflection to perhaps 35-50%. This increases the perceived level of contrast.

A major challenge in dome construction is to make seams as invisible as possible. Painting a dome after installation is a major task, and if done properly, the seams can be made almost to disappear.

Traditionally, planetarium domes were mounted horizontally, matching the natural horizon of the real night sky. However, because that configuration requires highly inclined chairs for comfortable viewing "straight up", increasingly domes are being built tilted from the horizontal by between 5 and 30 degrees to provide greater comfort. Tilted domes tend to create a favoured "sweet spot" for optimum viewing, centrally about a third of the way up the dome from the lowest point. Tilted domes generally have seating arranged stadium-style in straight, tiered rows; horizontal domes usually have seats in circular rows, arranged in concentric (facing center) or epicentric (facing front) arrays.

Planetaria occasionally include controls such as buttons or joysticks in the arm rests of seats to allow audience feedback that influences the show in real time.

Often around the edge of the dome (the "cove") are:

* Silhouette models of geography or buildings like those in the area round the planetarium building.
* Lighting to simulate the effect of twilight or urban light pollution.

Traditionally, planetariums needed many incandescent lamps around the cove of the dome to help audience entry and exit, to simulate sunrise and sunset, and to provide working light for dome cleaning. More recently, solid-state LED lighting has become available that significantly decreases power consumption and reduces the maintenance requirement as lamps no longer have to be changed on a regular basis.

The world's largest mechanical planetarium is located in Monico, Wisconsin. The Kovac Planetarium. It is 22 feet in diameter and weighs two tons. The globe is made of wood and is driven with a variable speed motor controller. This is the largest mechanical planetarium in the world, larger than the Atwood Globe in Chicago (15 feet in diameter) and one third the size of the Hayden.

Some new planetariums now feature a glass floor, which allows spectators to stand near the center of a sphere surrounded by projected images in all directions, giving the impression of floating in outer space. For example, a small planetarium at AHHAA in Tartu, Estonia features such an installation, with special projectors for images below the feet of the audience, as well as above their heads.

Traditional electromechanical/optical projectors

Traditional planetarium projection apparatus use a hollow ball with a light inside, and a pinhole for each star, hence the name "star ball". With some of the brightest stars (e.g. Sirius, Canopus, Vega), the hole must be so big to let enough light through that there must be a small lens in the hole to focus the light to a sharp point on the dome. In later and modern planetarium star balls, the individual bright stars often have individual projectors, shaped like small hand-held torches, with focusing lenses for individual bright stars. Contact breakers prevent the projectors from projecting below the "horizon".

The star ball is usually mounted so it can rotate as a whole to simulate the Earth's daily rotation, and to change the simulated latitude on Earth. There is also usually a means of rotating to produce the effect of precession of the equinoxes. Often, one such ball is attached at its south ecliptic pole. In that case, the view cannot go so far south that any of the resulting blank area at the south is projected on the dome. Some star projectors have two balls at opposite ends of the projector like a dumbbell. In that case all stars can be shown and the view can go to either pole or anywhere between. But care must be taken that the projection fields of the two balls match where they meet or overlap.

Smaller planetarium projectors include a set of fixed stars, Sun, Moon, and planets, and various nebulae. Larger projectors also include comets and a far greater selection of stars. Additional projectors can be added to show twilight around the outside of the screen (complete with city or country scenes) as well as the Milky Way. Others add coordinate lines and constellations, photographic slides, laser displays, and other images.

Each planet is projected by a sharply focused spotlight that makes a spot of light on the dome. Planet projectors must have gearing to move their positioning and thereby simulate the planets' movements. These can be of these types:-

* Copernican. The axis represents the Sun. The rotating piece that represents each planet carries a light that must be arranged and guided to swivel so it always faces towards the rotating piece that represents the Earth. This presents mechanical problems including:

The planet lights must be powered by wires, which have to bend about as the planets rotate, and repeatedly bending copper wire tends to cause wire breakage through metal fatigue.

When a planet is at opposition to the Earth, its light is liable to be blocked by the mechanism's central axle. (If the planet mechanism is set 180° rotated from reality, the lights are carried by the Earth and shine towards each planet, and the blocking risk happens at conjunction with Earth.)

* Ptolemaic. Here the central axis represents the Earth. Each planet light is on a mount which rotates only about the central axis, and is aimed by a guide which is steered by a deferent and an epicycle (or whatever the planetarium maker calls them). Here Ptolemy's number values must be revised to remove the daily rotation, which in a planetarium is catered for otherwise. (In one planetarium, this needed Ptolemaic-type orbital constants for Uranus, which was unknown to Ptolemy.)

* Computer-controlled. Here all the planet lights are on mounts which rotate only about the central axis, and are aimed by a computer.

Despite offering a good viewer experience, traditional star ball projectors suffer several inherent limitations. From a practical point of view, the low light levels require several minutes for the audience to "dark adapt" its eyesight. "Star ball" projection is limited in education terms by its inability to move beyond an Earth-bound view of the night sky. Finally, in most traditional projectors the various overlaid projection systems are incapable of proper occultation. This means that a planet image projected on top of a star field (for example) will still show the stars shining through the planet image, degrading the quality of the viewing experience. For related reasons, some planetariums show stars below the horizon projecting on the walls below the dome or on the floor, or (with a bright star or a planet) shining in the eyes of someone in the audience.

However, the new breed of Optical-Mechanical projectors using fiber-optic technology to display the stars show a much more realistic view of the sky.

Digital projectors

An increasing number of planetariums are using digital technology to replace the entire system of interlinked projectors traditionally employed around a star ball to address some of their limitations. Digital planetarium manufacturers claim reduced maintenance costs and increased reliability from such systems compared with traditional "star balls" on the grounds that they employ few moving parts and do not generally require synchronisation of movement across the dome between several separate systems. Some planetariums mix both traditional opto-mechanical projection and digital technologies on the same dome.

In a fully digital planetarium, the dome image is generated by a computer and then projected onto the dome using a variety of technologies including cathode ray tube, LCD, DLP, or laser projectors. Sometimes a single projector mounted near the centre of the dome is employed with a fisheye lens to spread the light over the whole dome surface, while in other configurations several projectors around the horizon of the dome are arranged to blend together seamlessly.

Digital projection systems all work by creating the image of the night sky as a large array of pixels. Generally speaking, the more pixels a system can display, the better the viewing experience. While the first generation of digital projectors were unable to generate enough pixels to match the image quality of the best traditional "star ball" projectors, high-end systems now offer a resolution that approaches the limit of human visual acuity.

LCD projectors have fundamental limits on their ability to project true black as well as light, which has tended to limit their use in planetaria. LCOS and modified LCOS projectors have improved on LCD contrast ratios while also eliminating the “screen door” effect of small gaps between LCD pixels. “Dark chip” DLP projectors improve on the standard DLP design and can offer relatively inexpensive solution with bright images, but the black level requires physical baffling of the projectors. As the technology matures and reduces in price, laser projection looks promising for dome projection as it offers bright images, large dynamic range and a very wide color space.

Show content

Worldwide, most planetariums provide shows to the general public. Traditionally, shows for these audiences with themes such as "What's in the sky tonight?", or shows which pick up on topical issues such as a religious festival (often the Christmas star) linked to the night sky, have been popular. Live format is preferred by many venues as a live speaker or presenter can answer questions raised by the audience.

Since the early 1990s, fully featured 3-D digital planetariums have added an extra degree of freedom to a presenter giving a show because they allow simulation of the view from any point in space, not only the Earth-bound view which we are most familiar with. This new virtual reality capability to travel through the universe provides important educational benefits because it vividly conveys that space has depth, helping audiences to leave behind the ancient misconception that the stars are stuck on the inside of a giant celestial sphere and instead to understand the true layout of the Solar System and beyond. For example, a planetarium can now 'fly' the audience towards one of the familiar constellations such as Orion, revealing that the stars which appear to make up a co-ordinated shape from an Earth-bound viewpoint are at vastly different distances from Earth and so not connected, except in human imagination and mythology. For especially visual or spatially aware people, this experience can be more educationally beneficial than other demonstrations.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1898 2023-09-12 00:05:19

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1902) Button


Buttons are small hard objects sewn on to shirts, coats, or other pieces of clothing. You fasten the clothing by pushing the buttons through holes called buttonholes.


A button is usually disklike piece of solid material having holes or a shank through which it is sewed to one side of an article of clothing and used to fasten or close the garment by passing through a loop or hole in the other side. Purely decorative, nonutilitarian buttons are also frequently used on clothing.

In medieval Europe, garments were laced together or fastened with brooches or clasps and points, until buttonholes were invented in the 13th century. Then buttons became so prominent that in some places sumptuary laws were passed putting limits on their use.

By the 14th century buttons were worn as ornaments and fastenings from the elbow to the wrist and from the neckline to the waist. The wearing of gold, silver, and ivory buttons was an indication of wealth and rank. Expensive buttons were also made of copper and its alloys. The metalsmith frequently embellished such buttons with insets of ivory, tortoiseshell, and jewels. More commonly, buttons were made of bone or wood. Button forms of these materials were also used as foundations for fabric-covered buttons. Thread buttons were made by wrapping the thread over a wire ring.

In the 18th century luxury metals and ivory largely replaced fabric, although embroidered buttons in designs to complement particular garments were popular. Pewter, the familiar metal of the age, was used to make molded or stamped-out buttons, but these were scorned by the wealthy. Cast brass buttons, particularly calamine brass, with ornamental and distinguishing designs, also became popular on both military and civilian dress.

In the middle of the 18th century, Matthew Boulton, the English manufacturer and partner of James Watt, introduced the bright, costly, cut-steel button, which was made by attaching polished steel facets to a steel blank. In France the facets of the cut-steel button were elaborated by openwork designs. During the first quarter of the 19th century, a less costly stamped steel button was made in an openwork pattern. Brass buttons that were gilded by dipping in an amalgam of mercury and gold also became popular.

The two-shell metal button was introduced about the same time as the stamped-steel type by B. Sanders, a Danish manufacturer in England. The two shells, thin metal disks enclosing a small piece of cloth or pasteboard, were crimped together on the edges. Sanders also originated the canvas shank. By 1830 fabric-covered buttons were being made mechanically. Also coming into use were animal horns and hoofs, which could be made malleable by heating and then could be cut, dyed, and molded.

Buttons were also made of ceramics and glass. Porcelain buttons became a French specialty; they were decorated by hand painting or by transfer printing designs using coloured inks. Bohemia, in the present-day Czech Republic, produced most of the coloured glass used in button manufacture.

In Japan, ceramic buttons, hand painted in traditional motifs, were developed. Buttons with an intricately carved thickness of vermilion lacquer on a wooden base became a Chinese specialty, and decorated and lacquered papier-mâché buttons became popular in Europe in the late 1800s.

The use of the pearly shells of sea mollusks in button making increased with the mechanization of production. Shell was separated into its component layers by treatment with a nitric acid solution, and blanks were cut out by tubular saws. Holes were bored in the blanks for sewing, and an engraved decoration was mechanically applied. At first only seashell was used, but in the 1890s the American manufacturer John F. Boepple began to use the less iridescent but abundant freshwater mussel shells found along the Mississippi River and its tributaries.

In the 20th century, buttons became primarily utilitarian, not decorative, and in many applications were supplanted by the zipper. Buttons began to be made of plastics such as cellulose, polystyrene, and polyvinyl resins; designs tended to be abstract or geometric. Mass-production machines produce molded buttons either by compressing powdered plastics or by injection—forcing liquid plastic into individual molds through small openings.

Some old buttons are considered valuable and are collected for their art and workmanship. The place, date, and name of the maker are usually marked on their backs.


A button is a fastener that joins two pieces of fabric together by slipping through a loop or by sliding through a buttonhole.

In modern clothing and fashion design, buttons are commonly made of plastic but also may be made of metal, wood, or seashell. Buttons can also be used on containers such as wallets and bags. Buttons may be sewn onto garments and similar items exclusively for purposes of ornamentation. In the applied arts and craft, a button can be an example of folk art, studio craft, or even a miniature work of art. In archaeology, a button can be a significant artifact.


Buttons and button-like objects used as ornaments or seals rather than fasteners have been discovered in the Indus Valley civilization during its Kot Diji phase (c. 2800–2600 BC), at the Tomb of the Eagles, Scotland (2200-1800 BC), and at Bronze Age sites in China (c. 2000–1500 BC) and Ancient Rome.

Buttons made from seashell were used in the Indus Valley Civilization for ornamental purposes by 2000 BC. Some buttons were carved into geometric shapes and had holes pierced into them so that they could be attached to clothing with thread. Ian McNeil (1990) holds that "the button was originally used more as an ornament than as a fastening, the earliest known being found at Mohenjo-daro in the Indus Valley. It is made of a curved shell and about 5000 years old."

Egypt’s Eighteenth Dynasty left behind ornate wig covers, fabricated through sewing buttons formed of precious metals onto strips of backing material.

Leatherwork from the Roman Empire incorporates some of the first buttonholes, with the legionary Loculus (satchel) closed through the insertion of a metallic buckle, or button into a leather slit. A similar mechanism would later feature in early medieval footwear. Buttons appeared as a means to close cuffs in the Byzantine Empire and to fasten the necks of Egyptian tunics by no later than the 5th century.

As containers

Since at least the seventeenth century, when box-like metal buttons were constructed especially for the purpose, buttons have been one of the items in which drug smugglers have attempted to hide and transport illegal substances. At least one modern smuggler has tried to use this method.

Also making use of the storage possibilities of metal buttons, during the World Wars, British and U.S. military locket buttons were made, containing miniature working compasses.

Materials and manufacture

Because buttons have been manufactured from almost every possible material, both natural and synthetic, and combinations of both, the history of the material composition of buttons reflects the timeline of materials technology.

Buttons can be individually crafted by artisans, craftspeople or artists from raw materials or found objects (for example fossils), or a combination of both. Alternatively, they can be the product of low-tech cottage industry or can be mass-produced in high-tech factories. Buttons made by artists are art objects, known to button collectors as "studio buttons" (or simply "studios", from studio craft).

In 1918, the US government made an extensive survey of the international button market, which listed buttons made of vegetable ivory, metal, glass, galalith, silk, linen, cotton-covered crochet, lead, snap fasteners, enamel, rubber, buckhorn, wood, horn, bone, leather, paper, pressed cardboard, mother-of-pearl, celluloid, porcelain, composition, tin, zinc, xylonite, stone, cloth-covered wooden forms, and papier-mâché. Vegetable ivory was said to be the most popular for suits and shirts, and papier-mâché far and away the commonest sort of shoe button.

Nowadays, hard plastic, seashell, metals, and wood are the most common materials used in button-making; the others tending to be used only in premium or antique apparel, or found in collections.

Over 60% of the world's button supply comes from Qiaotou, Yongjia County, China.

Decoration and coating techniques

Historically, fashions in buttons have also reflected trends in applied aesthetics and the applied visual arts, with buttonmakers using techniques from jewellery making, ceramics, sculpture, painting, printmaking, metalworking, weaving and others. The following are just a few of the construction and decoration techniques that have been used in button-making:

* Arita porcelain
* Cloisonné
* Daguerreotype
* Electroplating
* Embroidery
* Filigree
* Intaglio
* Lacquerware
* Lithography
* Metallizing
* Metal openwork
* Opus interassile
* Passementerie
* Portrait miniatures
* Satsuma ware
* Vitreous enamel

Styles of attachment

* Flat or sew-through buttons have holes through which thread is sewn to attach the button. Flat buttons may be attached by sewing machine rather than by hand, and may be used with heavy fabrics by working a thread shank to extend the height of the button above the fabric.

* Shank buttons have a hollow protrusion on the back through which thread is sewn to attach the button. Button shanks may be made from a separate piece of the same or a different substance as the button itself, and added to the back of the button, or be carved or moulded directly onto the back of the button, in which latter case the button is referred to by collectors as having a 'self-shank'.

* Stud buttons (also push-through buttons or just studs) are composed from an actual button, connected to a second, button-like element by a narrow metal or plastic bar. Pushed through two opposing holes within what is meant to be kept together, the actual button and its counterpart press it together, keeping it joined. Popular examples of such buttons are shirt studs and cufflinks.

* Snap fasteners (also pressure buttons or press studs) are metal (usually brass) round discs pinched through the fabric. They are often found on clothing, in particular on denim pieces such as pants and jackets. They are more securely fastened to the material. As they rely on a metal rivet attached securely to the fabric, pressure buttons are difficult to remove without compromising the fabric's integrity. They are made of two couples: the male stud couple and the female stud couple. Each couple has one front (or top) and rear (or bottom) side (the fabric goes in the middle).
Short stick on a cord (attached centrally), with both ends of the stick passed through a seperate loop of cord.

* Toggles are stick-like, with a cord attached at the center. They are passed endways through a hole and then rotated sideways.

* Magnetic buttons, as the name implies, are buttons that attach to each other by being magnetic.[25] The buttons can be attached either by sewing or snapping them into the fabric.

Fabric buttons

* Covered buttons are fabric-covered forms with a separate back piece that secures the fabric over the knob.
* Mandarin buttons or frogs are knobs made of intricately knotted strings. Mandarin buttons are a key element in Mandarin dress (Qi Pao and cheongsam in Chinese), where they are closed with loops. Pairs of mandarin buttons worn as cuff links are called silk knots.
* Worked or cloth buttons are created by embroidering or crocheting tight stitches (usually with linen thread) over a knob or ring called a form. Dorset buttons, handmade from the 17th century to 1750, and Death head buttons are of this type.

Button sizes

The size of the button depends on its use. Shirt buttons are generally small, and spaced close together, whereas coat buttons are larger and spaced further apart. Buttons are commonly measured in lignes (also called lines and abbreviated L), with 40 lines equal to 1 inch. For example, some standard sizes of buttons are 16 lignes (10.16 mm, standard buttons of men's shirts) and 32 lignes (20.32 mm, typical button on suit jackets).

In museums and galleries

Some museums and art galleries hold culturally, historically, politically, and/or artistically significant buttons in their collections. The Victoria and Albert Museum has many buttons, particularly in its jewellery collection, as does the Smithsonian Institution.

Hammond Turner & Sons, a button-making company in Birmingham, hosts an online museum with an image gallery and historical button-related articles, including an 1852 article on button-making by Charles Dickinson. In the US, large button collections are on public display at the Waterbury Button Museum of Waterbury, Connecticut, the Keep Homestead Museum of Monson, Massachusetts, which also hosts an extensive button archive, and in Gurnee, Illinois, at The Button Room.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1899 2023-09-13 00:13:37

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1903) Balloon


A balloon is a small, thin rubber bag that you blow air into or fill with a light gas until it is round in shape, used for decoration, as a children's toy, or for other purposes such as medical treatment or scientific research.


A balloon is a large airtight bag filled with hot air or a lighter-than-air gas, such as helium or hydrogen, to provide buoyancy so that it will rise and float in the atmosphere. Transport balloons have a basket or container hung below for passengers or cargo. A self-propelled steerable balloon is called an airship or a dirigible.

Balloons were used in the first successful human attempts at flying. Experimentation with balloonlike craft may have begun as early as 1709 with the work of Bartolomeu Lourenço de Gusmão, a Brazilian priest and inventor. In 1783 Joseph and Étienne Montgolfier at Annonay, France, confirmed that a fabric bag filled with hot air would rise. On June 4 of that year they launched an unmanned balloon that traveled more than 1.5 miles (2.4 km). At Versailles they repeated the experiment with a larger balloon on September 19, 1783, sending a sheep, rooster, and duck aloft.

On November 21, 1783, the first manned flight took place when Jean-François Pilâtre de Rozier and François Laurent, marquis d’Arlandes, sailed over Paris in a Montgolfier balloon. They burned wool and straw to keep the air in the balloon hot; their flight covered 5.5 miles (almost 9 km) in about 23 minutes. In December of that year the physicist Jacques Charles, accompanied by Nicolas-Louis Robert, flew a balloon filled with hydrogen on a two-hour flight.

Military uses for balloons were soon developed. Anchored observation balloons were used by Napoleon in some of his battles and by both sides in the American Civil War and in World War I. The powered airship developed from balloons, but, while the airship was eventually supplanted by the airplane, balloons have continued to find useful applications. During World War II, balloons were anchored over many parts of Britain to defend against low-level bombing or dive-bombing.

Balloons have also proved enormously valuable to science. As early as 1911–12, Victor Francis Hess, an Austrian physicist, made a daring series of balloon ascents as high as 5,000 metres (about 3 miles) to prove the existence of cosmic rays. Advances in weather science since 1900 have resulted in great part from intensive exploration of the upper air by instrumented free balloons, which have risen to an altitude of 30 km (19 miles). Auguste Piccard, Swiss physicist and educator, set a world’s altitude record in May 1931 in a balloon of his own design, which featured the first pressurized cabin used in flight. Jean-Felix Piccard, twin brother of Auguste, experimented with plastic balloons and helped to design the polyethylene Skyhook series of high-altitude balloons with which the U.S. Air Force sent manned flights to more than 100,000 feet (30,000 metres) to collect data on the upper atmosphere. Sport ballooning has gained in popularity over the years.


A balloon is a flexible bag that can be inflated with a gas, such as helium, hydrogen, nitrous oxide, oxygen, and air. For special tasks, balloons can be filled with smoke, liquid water, granular media (e.g. sand, flour or rice), or light sources. Modern day balloons are made from materials such as rubber, latex, polychloroprene, or a nylon fabric, and can come in many different colors. Some early balloons were made of dried animal bladders, such as the pig bladder. Some balloons are used for decorative purposes or entertaining purposes, while others are used for practical purposes such as meteorology, medical treatment, military defense, or transportation. A balloon's properties, including its low density and low cost, have led to a wide range of applications.

The rubber balloon was invented by Michael Faraday in 1824, during experiments with various gases. He invented them for use in the lab.



A toy balloon or party balloon is a small balloon mostly used for decoration, advertising and children's toys. Toy balloons are usually made of rubber or aluminized plastic, and inflated with air or helium. They come in a great variety of sizes and shapes, but are most commonly 10 to 30 centimetres (3.9 to 11.8 in) in diameter. Toy balloons are not considered to include "sky lanterns" (hot-air paper balloons), although these too are or were used as child toys in some parts of the world.

According to The Journal of the American Medical Association, out of 373 children who died in the US between 1972 and 1992 after choking on children's products, nearly a third choked on latex balloons. The Consumer Products Safety Commission found that children had inhaled latex balloons whole (often while trying to inflate them) or choked on fragments of broken balloons. Parents, a monthly magazine about raising children, advised parents to buy Mylar balloons instead of latex balloons.


Decorations made of balloons with a combination of stacking and twisting techniques showcasing the deco-twisting style.
Balloons are used for decorating birthday parties, weddings, corporate functions, school events, and for other festive gatherings. The artists who use the round balloons to build are called "stackers" and the artists who use pencil balloons to build are called "twisters." Most commonly associated with helium balloon decor, more recently balloon decorators have been moving towards the creation of air-filled balloon decorations due to the non-renewable natural resource of helium limited in supply. The most common types of balloon decor include arches, columns, centerpieces, balloon drops, sculptures, and balloon bouquets. With the increased aptitude for balloon twisting as well as balloon stacking, the rise of the deco-twister manifests itself as the combination of stacking techniques as well as twisting techniques to create unique and interesting balloon decor options.

Party Balloons

Party balloons are mostly made of a natural latex tapped from rubber trees, and can be filled with air, helium, water, or any other suitable liquid or gas. The rubber's elasticity makes the volume adjustable.

Twisting balloons can be used to create decor centerpieces for events and to create a more unique look than can be provided by foil balloons.

Often the term "party balloon" will refer to a twisting balloon or pencil balloon. These balloons are manipulated to create shapes and figures for parties and events, typically along with entertainment.

Filling the balloon with air can be done with the mouth, a manual or electric inflater (such as a hand pump), or with a source of compressed gas.

When rubber or plastic balloons are filled with helium so that they float, they typically retain their buoyancy for only a day or so, sometimes longer. The enclosed helium atoms escape through small pores in the latex which are larger than the helium atoms. However, some types of balloons are labelled "helium-grade". These balloons are often thicker and have less porosity. Balloons filled with air usually hold their size and shape much longer, sometimes for up to a week.

However, a rubber balloon eventually loses gas to the outside. The process by which a substance or solute migrates from a region of high concentration, through a barrier or membrane, to a region of lower concentration is called diffusion. The inside of balloons can be treated with a special gel (for instance, the polymer solution sold under the "Hi Float" brand) which coats the inside of the balloon to reduce the helium leakage, thus increasing float time to a week or longer.

Animal-shaped balloons

Beginning in the late 1970s, some more expensive (and longer-lasting) foil balloons made of thin, unstretchable, less permeable metallised films such as Mylar (BoPET) started being produced. These balloons have attractive shiny reflective surfaces and are often printed with color pictures and patterns for gifts and parties. The most important attributes of metallised nylon for balloons are its light weight, increasing buoyancy, and its ability to keep the helium gas from escaping for several weeks. Foil balloons have been criticized for interfering with power lines.


Balloon artists are entertainers who twist and tie inflated tubular balloons into sculptures such as animals. The balloons used for sculpture are made of extra-stretchy rubber so that they can be twisted and tied without bursting. Since the pressure required to inflate a balloon is inversely proportional to the diameter of the balloon, these tiny tubular balloons are extremely hard to inflate initially. A pump is usually used to inflate these balloons.

Decorators may use helium balloons to create balloon sculptures. Usually the round shape of the balloon restricts these to simple arches or walls, but on occasion more ambitious "sculptures" have been attempted. It is also common to use balloons as table decorations for celebratory events. Balloons can sometimes be modeled to form shapes of animals. Table decorations normally appear with three or five balloons on each bouquet. Ribbon is curled and added with a weight to keep the balloons from floating away.

Drops and releases

A decorative use for balloons is in balloon drops. In a balloon drop, a plastic bag or net filled with air-inflated balloons is suspended from a fixed height. Once released, the balloons fall onto their target area below. Balloon drops are commonly performed at New Year's Eve celebrations and at political rallies and conventions, but may also be performed at celebrations, including graduations and weddings.

For decades, people have also celebrated with balloon releases. This practice has been discouraged by the balloon industry, as it has posed problematic for the environment and cities. In recent years, legislation such as the California Balloon Law has been enacted to enforce consumers and retailers to tether helium-filled foil (BoPET) balloons with a balloon weight. This ensures that the helium-filled balloons do not float into the atmosphere, which is potentially injurious to animals, the environment, and power lines. Many states now have banned balloon releases.

It is becoming more common for balloons to be filled with air instead of helium, as air-filled balloons will not release into the atmosphere or deplete the earthly helium supply. There are numerous party games and school-related activities that can use air-filled balloons as opposed to helium balloons. When age appropriate, these activities often include the added fun of blowing the balloons up. In many events, the balloons will contain prizes, and party-goers can pop the balloons to retrieve the items inside.


Balloons are used for publicity at major events. Screen printing processes can be used to print designs and company logos onto the balloons. Custom built printers inflate the balloon and apply ink with elastic qualities through a silk screen template. In January 2008, the Jewish Community Relations Council of New York organized a display of 4,200 red balloons outside the United Nations Headquarters.

Also in the 1950s at the start of the Cold War, activists in Western Europe uses balloons for propaganda purposes that would float east over Eastern Europe, which would release newspapers and pamphlets. In 2014, South Korean activists used the same balloon method to get information to those in North Korea.

Paolo Scannavino set the record of 11 for the most giant balloons entered in 2 minutes.

Water projection

Water balloons are thin, small rubber balloons filled with a liquid, usually water, instead of a gas, and intended to be easily broken. They are usually used by children, who throw them at each other, trying to get each other wet, as a game, competition, or practical joke. By forcing water out the open end of a water balloon, it is possible to use it as a makeshift water gun.

Solar lift

Solar balloons are thin, large balloons filled with air that is heated by the sun in order to decrease its density to obtain lift.


Balloons are often deliberately released, creating a so-called balloon rocket. Balloon rockets work because the elastic balloons contract on the air within them, and so when the mouth of the balloon is opened, the gas within the balloon is expelled out, and due to Newton's third law of motion, the balloon is propelled forward. This is the same way that a rocket works.

Flying machines

Balloons filled with hot air or a buoyant gas have been used as flying machines since the 18th century. The earliest flights were made with hot air balloons using air heated with a flame, or hydrogen as the lifting gas. Later, coal gas and later still helium were used. An unpowered balloon travels with the wind. A balloon which has an engine to propel it is called a dirigible balloon or airship.


Angioplasty is a surgical procedure in which very small balloons are inserted into blocked or partially blocked blood vessels near the heart. Once in place, the balloon is inflated to clear or compress arterial plaque, and to stretch the walls of the vessel, thus preventing myocardial infarction. A small stent can be inserted at the angioplasty site to keep the vessel open after the balloon's removal.

Balloon catheters are catheters that have balloons at their tip to keep them from slipping out. For example, the balloon of a Foley catheter is inflated when the catheter is inserted into the urinary bladder and secures its position.

Insertion of balloons subsequently filled with air or liquid can be used to stop bleeding in hollow internal organs such as stomach or uterus.


Humans have intentionally filled bladders, especially actual animal bladders, with air since prehistory. In Ancient Greece, these had a number of recorded uses. The Aztecs inflated cat intestines to make shapes to present as sacrifices to the gods. By the 18th century, people were inflating balloons of cloth or canvas with hot air and sending it aloft, the Montgolfier brothers going so far as to experiment with first animals in 1782, and then, when altitude did not kill them, human beings in 1783.

The first hydrogen-filled gas balloon was flown in the 1790s. A century later the first hydrogen-filled weather balloons were launched in France.

The first modern rubber balloons on record were made by Michael Faraday in 1824. He used these to contain gasses he was experimenting with, especially hydrogen. By 1825 similar balloons were being sold by Thomas Hancock, but like Faraday's they came disassembled, as two circles of soft rubber. The user was expected to lay the circles one on top of the other and rub their edges until the soft, gummy rubber stuck, leaving the powdered inner part loose for inflation. Modern, preassembled balloons were being sold in the US by the early 20th century.

Safety and environmental concerns

There has been some environmental concern over metallised Mylar balloons, as they do not biodegrade or shred as rubber balloons do. Release of these types of balloons into the atmosphere is considered harmful to the environment. This type of balloon can also conduct electricity on its surface and released foil balloons can become entangled in power lines and cause power outages.

Released balloons can land anywhere, including on nature reserves or other areas where they can pose a hazard to animals through ingestion or entanglement. Because of the potential harm to wildlife and the effect of litter on the environment, some jurisdictions even legislate to control mass balloon releases. Legislation proposed in Maryland, US, was named after Inky, a pygmy sperm whale who needed six operations after swallowing debris, the largest piece of which was a Mylar balloon. The Balloon Council, a trade organization that represents the interests of balloon businesses, claims that there is no documentary evidence to suggest that the death of any sea mammal has been attributed to foil balloons as a sole cause, to date. In the United Kingdom, foil balloons sold at major theme parks and zoos have balloon weights attached to help prevent accidental release into the environment.

When balloons eventually return to the ground, they begin the degradation process. Latex balloons are the most used because of their ability to biodegrade. The problem with this is that it can take at least 4 weeks to show substantial degradation of the polymer in the environment, and around 6 months in aquatic environments. This issue can have an effect on the wildlife on both land and in aquatic systems because animals will confuse deflated balloons as food, nesting material, or simply something to play with. When that happens, it can lead to negative effects for the animals. For example, a bird can use a deflated balloon as a component for its nest. When the eggs hatch, they will get tangled in the balloon and that can lead to death.

Anthony Andrady says that releases of latex balloons that descend into the sea pose a serious ingestion and/or entanglement hazard to marine animals because balloons exposed floating in seawater deteriorate much more slowly than those exposed in air. Balloon manufacturers will often state that a latex balloon is perfectly safe to release into the environment as it is made from a natural substance and will biodegrade over time. A latex balloon can take up to a year to degrade if it lands in the sea and during this time it is possible for a marine animal to ingest the balloon and die from slow starvation if its digestive system is blocked.

NABAS (National Association of Balloon Artists and Suppliers), an organisation that styles itself "The Balloon and Party Professionals Association" and represents the UK balloon industry, publishes guidelines for people holding balloon releases. some of the leading balloon manufacturers have started to recommend avoiding balloon releasing, instead preferring to tie balloons down with weights in order to prevent them from floating away. These recommendations have also been adopted by some industry professionals working with balloons in the fields of design and entertainment.


Traditionally balloons are manufactured from plastic. With the rise of worldwide awareness for environmental conservation, some balloon manufacturers started making balloons out of biodegradable materials, which are made entirely of natural recyclable rubber trees. These balloons manufacturing processes preserve the natural state of the material in such a way that allows it to degrade relatively quickly. Some of the manufacturers only use rubber trees that are grown in plantations that receive the Rainforest Alliance's approval, and at which its representatives conduct regular inspections in order to make sure that the farmers meet several criteria set to ascertain that the biological diversity in the area is maintained, and that no worker or natural resource is abused in the material manufacturing process.

Another environmental problem with latex balloons is not the effects the balloons have on the environment once they are decomposed, but when they are being made. When latex is being produced, it produces greenhouse gases, such as CO2, CH4, N2O. This is becoming an increasing problem, especially in Thailand which is responsible for 35% of the worlds natural rubber production.

At the start of the 21st century, balloon recycling or reuse for other purposes was in its infancy. As of 2020, several balloon manufacturers have developed methods for effective balloon waste disposal, and some manufacturers use recycled balloons to produce other products, such as toys for pets.

Air pressure

Once inflated with regular, atmospheric air, the air inside the balloon will have a greater air pressure than the original atmospheric air pressure.

Air pressure, technically, is a measurement of the amount of collisions against a surface at any time. In the case of balloon, it's supposed to measure how many particles at any in any given time space collide with the wall of the balloon and bounce off. Since this is nearly impossible to measure, air pressure seems to be more easily described as density. The similarity comes from the idea that when there are more molecules in the same space, more of them will be heading towards a collision course with the wall.

The first concept of air pressure within a balloon that is necessary to know is that air pressures "try" to even out. With all the bouncing against the balloon wall (both interior and exterior) there will be a certain amount of expansion/contraction. As air pressure itself is a description of the total forces against an object, each of these forces, on the outside of the balloon, causes the balloon to contract a tiny bit, while the inside forces cause the balloon to expand. With this knowledge, one would immediately assume that a balloon with high air pressure inside would expand based on the high amount of internal forces, and vice versa. This would make the inside and outside air pressures equal.

Balloons have a certain elasticity to them that needs to be taken into account. The act of stretching a balloon fills it with potential energy. When it is released, the potential energy is converted to kinetic energy and the balloon snaps back into its original position, though perhaps a little stretched out. When a balloon is filled with air, the balloon is being stretched. While the elasticity of the balloon causes tension that would have the balloon collapse, it is also being pushed back out by the constant bouncing of the internal air molecules. The internal air has to exert force not only to counteract the external air to keep the air pressures "even", but it also has to counteract the natural contraction of the balloon. Therefore, it requires more air pressure (or force) than the air outside the balloon wall. Because of this, when helium balloons are left and they float higher, as atmospheric pressure decreases, the air inside it exerts more pressure than outside it so the balloon pops from tension. In some cases, the helium leaks out from pores and the balloon deflates, falling down.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


#1900 2023-09-14 00:12:22

Jai Ganesh
Registered: 2005-06-28
Posts: 46,162

Re: Miscellany

1904) Hot air ballooning


Hot air ballooning entails the pilot riding inside a wicker basket attached to a huge balloon made of rip-stop nylon. The balloon has a burner which is positioned between he wicker basket and the balloon. The flame of the burner heats the air inside the balloon and makes it rise. The degree to which the balloon air is heated depends on the atmospheric conditions, also on how high the pilot wants the balloon to go, and, of course, the fuel. To descend, the pilot allows the air to cool, and with the balloon becoming heavier than air, it loses height. Thus, by controlling the heat in the balloon, the pilot has complete control of the up-and-down movement of the balloon. Once the hot air balloon has taken off, the wind conditions decide its direction. But this does not mean that the pilot does not have control over its course. The different layers of air are usually moving in different directions and the pilot has to move up and down to find a layer that would take him or her in the desired direction. This is where the skill of the pilot comes into play, where, without physically steering the balloon, the pilot controls the direction of the balloon.


Hot air ballooning is the recreational and competitive adventure sport of flying hot air balloons. Attractive aspects of ballooning include the exceptional quiet (except when the propane burners are firing), the lack of a feeling of movement, and the bird's-eye view. Since the balloon moves with the direction of the winds, the passengers feel absolutely no wind, except for brief periods during the flight when the balloon climbs or descends into air currents of different direction or speed. Hot air ballooning has been recognized by Fédération Aéronautique Internationale (FAI) as the safest air sport in aviation, and fatalities in hot air balloon accidents are rare, according to statistics from the National Transportation Safety Board (NTSB).


The first clearly recorded instance of a balloon carrying passengers used hot air to generate buoyancy and was built by the brothers Joseph-Michel and Jacques-Etienne Montgolfier in Annonay, France. After experimenting with unmanned balloons and flights with animals, the first tethered balloon flight with humans on board took place on October 19, 1783, with the scientist Jean-François Pilâtre de Rozier, the manufacture manager, Jean-Baptiste Réveillon and Giroud de Villette, at the Folie Titon in Paris. The first free flight with human passengers was on November 21, 1783. King Louis XVI had originally decreed that condemned criminals would be the first pilots, but de Rozier, along with Marquis Francois d'Arlandes, successfully petitioned for the honor.

Modern revival

Modern hot air ballooning was born in 1960, when Ed Yost launched a balloon with a new nylon envelope and propane burner system of his own invention. Yost's first balloon was basketless, with nothing but a seat for him to ride on, but in a few years he and other balloon enthusiasts would develop balloons much like the ones used today.

Today, hot air balloons are used primarily for recreation. According to the FAA's General Aviation Survey data, in 2012, there were about 2,300 personally owned and flown balloons, and about 495 commercial sightseeing ride operators in the United States. Balloon rides are available in many locations around the world and are especially popular in tourist areas. At balloon festivals many balloons will fly at once, with other entertainment available.

Hot air balloons in flight

Hot air balloons are able to fly to extremely high altitudes. On November 26, 2005, Vijaypat Singhania set the world altitude record for highest hot air balloon flight, reaching 21,290 meters (69,850 feet). He took off from downtown Mumbai, India and landed 240 km (150 mi) south in Panchale. The previous record of 19,811 meters (64,997 feet) had been set by Per Lindstrand on June 6, 1988, in Plano, Texas. However, as with all unpressurised aircraft, oxygen is needed for all crew and passengers on any balloon flight that reaches and exceeds an altitude of 3,810 meters (12,500 feet).

On January 15, 1991, a balloon called the Pacific Flyer carrying Per Lindstrand (born in Sweden, but resident in the UK) and Richard Branson of the UK flew from Japan to Northern Canada, completing 7,671.91 km. With a volume of 74,000 m3 (2,600,000 cu ft), the balloon envelope was the largest ever built for a hot air craft. Designed to fly in the trans-oceanic jetstreams the Pacific Flyer recorded the highest ground speed for a manned balloon of 245 mph (394 km/h).

The distance record was broken on March 21, 1999, when the Breitling Orbiter 3 carrying Bertrand Piccard and Brian Jones touched down in Egypt, having circumnavigated the globe and set records for duration (19 days, 21 hours and 55 minutes) and distance (46,759 km).

Flight techniques

Most hot air balloon launches are made during the cooler hours of the day, at dawn or two to three hours before sunset. At these times of day, the winds are typically light making for easier launch and landing of the balloon. Flying at these times also avoids thermals, which are vertical air currents caused by ground heating that make it more difficult to control the balloon. In the extreme, the downdrafts associated with strong thermals can exceed the ability of a balloon to climb and can thus force a balloon into the ground.


Preflight preparation

Before a safe hot air balloon flight can begin, the pilot must check the weather and select a suitable take-off point. The current and forecast weather must have sufficient visibility for the pilot to see and avoid obstructions (little or no fog or low clouds) and sufficiently slow winds to allow take off and landing (less than 5 or 10 mph depending on skill and experience of pilot, passengers, and ground crew).

The take-off point must be large enough to lay out and inflate the envelope and clear of obstructions such as power lines and poles, trees, and buildings to allow lift-off under the predicted wind conditions. Finally, the take-off point must be situated such that the predicted winds will move the balloon in the direction of suitable landing sites. Taking off from a location that is directly up wind of a hazard, such as a large body of water, a large metropolitan area, or a large uninterrupted forest, without sufficient fuel to pass over the hazard is not safe.

Set up

The next step in a hot air balloon flight is unpacking the balloon from its carrying bag, laying it out on the ground, and connecting it to the basket and burner. A fan, often gasoline-powered, is used to blow cold (outside) air into the envelope. The cold air partially inflates the balloon to establish its basic shape before the burner flame is aimed into the mouth heating the air inside. A crew member stationed opposite the mouth, holds a rope (crown line) tied to the apex (crown) of the envelope. Some balloons, AX7 and larger, may have two (or more) crown lines. The "crown-man" role is twofold: one is to prevent the envelope from excessive sway, and two is to prevent the envelope from rising before it is sufficiently buoyant. Once the balloon is upright, pilot and passengers climb into the basket. When the pilot is ready for launch, more heat is directed into the envelope and the balloon lifts off.

The crew then pack up inflation equipment and follow the balloon with the retrieve vehicle (also called a chase vehicle).


During the flight, the pilot's only ability to steer the balloon is the ability to climb or descend into winds going different directions. Thus, it is important for the pilot to determine what direction the wind is blowing at altitudes other than the balloon's altitude. To do this, the pilot uses a variety of techniques. For example, to determine wind directions beneath the balloon a pilot might simply spit or release a squirt of shaving cream and watch this indicator as it falls to determine where possible turns are (and their speed). Pilots are also looking for other visual clues such as flags on flagpoles, smoke coming from chimneys, etc. To determine wind directions above the balloon, the pilot will obtain a weather forecast prior to the flight which includes upper-level wind forecasts. The pilot will also send up a helium pilot balloon, known as a met-balloon in the UK and pibal in the US, prior to launch to get information about what the wind is actually doing. Another way to determine actual wind directions is to watch other hot air balloons, which are the equivalent of a large met-balloon.


The direction of flight depends on the wind, but the altitude of the balloon can be controlled by changing the temperature of the air inside the envelope. The pilot may open one or more burner blast valves to increase the temperature inside the envelope, thereby increasing lift, and thus ascend or slow or stop a descent. The pilot may also open a vent, if the envelope is so equipped, to let hot air escape, decreasing the temperature inside the envelope, thereby decreasing lift, and thus descend or slow or stop an ascent. Unless the pilot intervenes, the air inside the envelope will slowly cool, by seepage or by contact with cooler outside air, and slowly provide less lift.

Delayed response

One of the tricks involved in flying a balloon is learning to deal with the delayed response. To slow or stop a descent requires the pilot to open a burner blast valve. This sends hot combustion exhaust through the mouth into the envelope where it expands and forces some cooler air out of the mouth. This lightens the total weight of the system and increases its buoyancy, but not immediately. From the time that the burner is lit until the balloon slows or stops its descent can take 30 seconds or more, depending on its rate of descent, how cold it has become, and how powerful the burner. This delay requires a great deal of anticipation on the part of the pilot.


The ability to change direction with altitude is called steerage. In the ideal case, in the northern hemisphere, wind direction turns to the right with an increase in altitude. This is due to the Coriolis effect. Winds spiral clockwise, when seen from above, out of a high pressure system and counter clockwise into a low pressure system. However, air travelling close to the ground will tend to move in more of a straight line from high to low pressure due to drag with the ground. Thus, a pilot may hope to find a turn to the left during the descent to landing. In the southern hemisphere, the direction of the spirals is reversed. In reality, interaction with an uneven terrain may lessen or eliminate this phenomenon.

Level flight

The burner is designed to create enough heat to warm up the balloon quickly. It is most efficient only when wide open. There is no good way to maintain the exact temperature required to maintain equilibrium.

Add to that the fact that when a hot air balloon is not actively being heated, it is cooling off. This means that it is in perfect equilibrium only momentarily. The rest of the time it is either too warm or too cool and so either climbing or descending.

These two facts together mean that under most conditions level flight is anything but. The goal of the pilot is to light the burner at the right interval and for the right duration (a few seconds) to keep the balloon slowly drifting up and down about the desired altitude.

An exception is made when flying close to the ground, as in an approach to a landing. Then the burner may be lit for very short bursts at a much higher frequency, thus sacrificing efficiency for accuracy.


While it is certainly possible to enjoy the sport of hot air ballooning without a chase vehicle, returning from the landing site by foot, bicycle, or hitch hiking, many balloonists opt to be followed by their ground crew in some sort of chase vehicle. Crew at the landing site can aid with the landing itself, by catching a drop line and guiding the balloon into a tight space; with extracting the balloon system from a remote location, such as deep in a farmer's field; and with packing up all the equipment.

Sometimes, a chase vehicle may be equipped with a trailer, which can provide more room at the cost of being more difficult to maneuver. A pickup truck or van by itself can be more maneuverable but at the cost of squeezing all the equipment, crew, pilot, and passengers into a single vehicle. Many chase vehicles are fitted with a cargo liftgate to aid in loading heavy equipment into the cargo space (the envelope itself can weigh 250 lbs or more).

Communication between the balloon and chase vehicle can be accomplished by two-way radio, or even shouting, when they are close enough together. The use of cell phones for this purpose, while the balloon is flying, may violate local telecommunication laws and should therefore be avoided except in an emergency situation.


Most pilots try to perform as smooth a landing as possible. This becomes difficult if the air at ground level is moving at more than 5 mph (2.2 m/s) or so. If the balloon is moving at this speed or more when it contacts the ground, the basket (which usually does not have wheels of any kind on the bottom) may drag for a bit or even tip over. Even the presence of ground crew may not help much. The combined weight (for an average passenger-carrying system as calculated above) can easily exceed the weight of a large automobile. (It is best not to be on the downwind side of a landing balloon to avoid being pinned between it and a hard place.) Pilots can improve the situation by landing in a spot protected from the wind, such as behind a line of trees or in a small valley.

Once the balloon has landed, the envelope is deflated and detached from the basket. The envelope is then packed into its carrying bag. The burner and the basket may be separated and all components are packed into the retrieve vehicle.


In competition, the pilots need to be able to read different wind directions at different altitudes. Balloon competitions are often called "races" but they are most often a test of accuracy, not speed. For most competitive balloon flights, the goal is to fly as close as possible to one or more exact points called "targets". Once a pilot has directed the balloon as close as possible to a target, a weighted marker with an identifying number written on it is dropped. The distance between a pilot's marker and that target determines his or her score. During some competitive flights, pilots will be required to fly to 5 or more targets before landing. To assist with navigation, topographic maps and GPS units are used. Another common form of competition is the "Hare and Hound" race. The Hare balloon takes off a set amount of time before the Hound balloons and typically flies with multiple altitude changes to make it more difficult for the chasing balloons to match its flight path. After a set amount of flight time, the Hare will land and typically lay out a target cross for the Hounds to drop their weighted markers near. As above, the distance between a pilot's marker and the target determines his or her score.

A balloonist prepares to drop a marker on a competition target, in this case the centre of a road intersection.
Some experienced pilots are able to take a flight in one direction then rise to a different altitude to catch wind in a returning direction. With experience, luck, and the right conditions, some pilots are able to control a precision landing at the destination. On rare occasions, they may be able to return to the launch site at the end of the flight. This is sometimes called a box effect, when winds at altitude flow in the opposite direction of surface winds.


The dangers of the sport include excessive (vertical or horizontal) speed during landing, mid-air collisions that may collapse the balloon, and colliding with high voltage power lines. It is the last of these, contact with power lines, that poses the greatest danger. One of the most common causes of serious ballooning accidents in the US is power line strikes. One reason for the high frequency of such incidents is the fact that pilots often attempt to land their balloons on or near roads in order to reduce the amount of off-road driving necessary to recover the balloon. However, in most rural areas where balloons fly, roads usually have power lines running along with them.

Of the 11 accidents involving fatalities recorded by the NTSB between 1997 and 2007, 4 involved contact with power lines, 3 involved falling after hanging onto the outside of a rising balloon, 3 involved striking an object on landing (boulder, wall, or tree), and 1 involved an equipment failure (an eyebolt).

Winter flight

The ability to fly hot air balloons in the winter is limited mostly by the ability of the participants to withstand the cold. The balloons themselves fly well in cold air. Because the temperature difference between inside and outside the balloon, not the absolute inside temperature, determines the lift it develops, a much lower internal temperature is sufficient to fly in cold weather.

However, if the liquid propane in the fuel tanks is too cold (0 °C [ 32 °F ]/ or less) it does not generate sufficient vapor pressure to adequately feed the burner(s). This can be overcome by charging the fuel tanks with inert gas such as nitrogen or by warming them, with electric heat tapes for example, and insulating them against the cold.


Sometimes, especially at balloon festivals or other special events, balloons are flown while tied to the ground with ropes (tethers). This enables quick rides to many passengers, instead of long rides drifting with the wind away from the event with one load of passengers. Tethering techniques depend on the balloon manufacturer's instructions and wind conditions. Tethers can be attached to the basket, burner support, or the top of the envelope. A "night glow" is a tethered flight in darkness to enhance visual effects. While typical day flights use the main valve, using an efficient blue flame, at night tethered pilots use the liquid valve "whisper burner" ("cow burner", as it does not startle livestock), creating a spectacular bright orange flame.

Though tethered, a balloon is considered a registered flying aircraft when it leaves the ground.


There are many regular gatherings of balloons and balloonists around the world. Most of these events are held on an annual basis. The festivities provide both a place for balloonists to interact as well as a venue for entertaining spectators. Events range in size from a few balloons and no spectators to hundreds of balloons with hundreds of thousands of spectators. The largest such event in the world is the Albuquerque International Balloon Fiesta, held every October in Albuquerque, New Mexico, followed by the Grand Est Mondial Air in France. The Bristol International Balloon Fiesta is another notable European event of this nature.

Additional Information

Hot-air balloons are commonly used for recreational purposes. In addition to quiet morning or afternoon flights drifting cross-country to enjoy the view, many balloonists enjoy competitive sporting events and attempting to set new records. A balloonist may fly alone in the basket or carry several passengers. Often several balloons meet to launch together without any competitive goals. Individual flights generally last from one to three hours and may go several kilometres, though they often land very close to the take-off point.

Balloon rallies may consist of just a few balloons for a one-day outing or up to several hundred balloons for a weeklong festival. Competitive events include distance within a time limit, spot landing, and “hare and hound” races. Hare and hound races are easy to organize and judge since they only require one (hare) balloon to launch first and fly a reasonable distance. The competitors attempt to land as close as possible to the hare’s landing position. In crowded conditions, markers are often dropped to simulate the landings, and the balloons fly on to more open locations.

Commercial ride operators are in business almost everywhere in the world. Some ride balloons carry 10 to 20 passengers at a time in gigantic partitioned baskets. In California and France, wine-country flights are popular tourist attractions. African safari flights, at low altitude over vast game preserves, are perhaps the pinnacle of ride ballooning.

Hot-air balloon components:

Envelope design

Hot-air balloons vary considerably in design and materials. Lightweight coated-nylon and polyester fabrics are the most common materials for envelopes. Cotton is very serviceable but has a comparatively poor weight-to-strength ratio. Specially shaped balloons, which are literally pneumatic sculptures, are popular at public events. They utilize special tailoring and many internal baffles and cords to attain the desired designs.

Sport balloons typically have a silhouette similar to the natural shape of fully inflated gas balloons. They can be assembled with many vertical gores (fabric sections, or panels) or fewer horizontal gores. The gore material can be cut straight (with the fabric’s natural grain) or on the bias (diagonal to the fabric’s natural grain). If straight gores are used, excess material can be gathered to create a fluted pattern that provides some flexibility. Gores made of bias-cut materials have greater stretch, which provides a natural flexibility. With horizontal gores, the individual panels can be gathered to provide a bulbous gore, which gives even greater flexibility. Because of the greatly reduced effective radius of curvature, a bulbous gore balloon experiences much less stress on the envelope fabric.

With bias gores, load tapes known as tensors are generally sewn loosely into ducts formed in the vertical seams, much like the shroud lines sewn into a parachute’s radial seams. With other balloons, the load is carried in tapes sewn or heat-sealed directly to the vertical seams. One load tape can and should have more than enough strength to carry the whole load without an excessive weight penalty. The stress in the skin of the balloon is so low that normal handling will cause visible damage if the fabric is weakened by wear or exposure long before it would fail in normal flight. The importance of load tapes and adequate excess strength in them in balloon construction cannot be overemphasized. Catastrophic failure in a properly designed balloon is extremely rare.

Deflation systems

Landing a bag with some four tons of air in it at 30 km (20 miles) per hour without wheels, steering gear, or brakes presents some problems. Prior to John Wise’s discovery of the rip panel deflation system in the mid-19th century, a gas balloon could be dragged along for several kilometres before coming to a stop. In particular, balloons on extended flights seemed to be drawn into low pressure systems, which often resulted in stormy landings.

The basic hot-air balloon rip panel is a simple large sleeve at the apex that is drawn into a bunch and tied off with a cord. The cord is typically cut remotely by an electrically actuated explosive squib cannon or released with a pull cord moments before touchdown in order to deflate the envelope rapidly. This configuration is known as a pop top. Other balloon models use a circular panel held in place with a hook-and-loop (e.g., Velcro) closure that can be opened and closed progressively for finer adjustments in buoyancy. That system is more often replaced with Tracy Barnes’s “parachute top,” which is a combination venting and deflation panel. The parachute top consists of a simple hole at the apex of the balloon, usually about one-quarter of the balloon’s diameter, plugged with a parachute of slightly greater diameter. The parachute is positioned by cords radiating out a few metres from the parachute’s edge to anchors located on the puffy gore centres. A venting cord leads from the juncture of the parachute’s shroud lines to the basket. Sometimes a mechanical advantage is gained by a pulley system. Pulling the cord draws the parachute down into the balloon, thereby letting hot air escape. Releasing the cord snaps the parachute back into the closed position with the force of the hot air. If the parachute is pulled far enough into the balloon, it will collapse, letting the balloon completely deflate rapidly. This is a great advantage in high-wind landings, where it might be difficult to maintain tension on the cord. Some versions use separate retracting cords to force the opening to close, redundant cinch cords to bunch the parachute for hands-off deflation, and elastic centring cords to provide automatic rapid setting and resetting of the parachute.


Hot-air balloons today use liquid propane burners exclusively. The burner’s vaporizing coils are generally made of steel, but copper tubing has been used with good results. A secondary system without vaporization and slower air mixing can provide much quieter operation and give redundancy for safety. Many designs have used multiple duplicate burners and fuel supplies because there has been a history of leaking seals on control valves and occasionally contaminated fuel.


Passenger baskets, or gondolas, vary as much in design as envelopes. For easy transportation, collapsible tubular frames with stout fabric covers can meet minimum requirements. Originally, wicker baskets had manila rope woven into the basket for suspension, but because of the potential for rot, these were replaced with synthetic or steel cables. Heavy wickerwork frames, using rattan up to a few centimetres in diameter, typically have also been replaced with metal or plastic framing.

Wicker construction has an advantage over metal skeletons and hard fibreglass shells in its absorption of the kinetic energy of impacts, however. Wicker is also favoured for its nostalgic artistic appearance. Any basket can have closed-cell foam padding on the inside for passenger safety and comfort.

Metallic components present hazards in the event of contact with electrical power lines. However, wickerwork by itself provides little protection to the passengers or fuel tanks from such contact. Vacuum-formed monocoque plastic baskets are slowly coming into use. They provide advanced impact and electrical contact resistance.

High-altitude ballooning

Beginning with the 18th century, ballooning has continually achieved higher altitudes. From Charles’s 3,000-metre (10,000-foot) ascent in 1783 to U.S. Army Air Corps Capt. Hawthorne C. Gray’s fatal ascent to 12,950 metres (42,470 feet) in 1927, the maximum altitude was only limited by the pilot’s need for oxygen. Lacking confidence in the ability to seal an aircraft hermetically, American aviation pioneer Wiley Post and others concentrated on individual pressure suits. Even as late as 1937, prominent aeronautical engineers publicly derided the concept of building airplane pressure cabins.

The Piccard invention of the stratosphere balloon (see above Balloons reach the stratosphere) opened up new heights for exploration. The first stratosphere flights were mounted to study cosmic rays, which are absorbed as they enter Earth’s atmosphere. Early high-altitude work with plastic balloons continued cosmic ray research, air sampling for detecting atomic explosions, photographic flights over foreign terrain, astronomical observations above the disturbances of the troposphere, and even aerodynamic testing of free-falling payloads. A balloon is the only stable platform for any type of observation above the range of airplanes and below the range of orbital spacecraft. It is also the only aircraft that does not affect its environment and the only device that can sit relatively motionless above heights obtainable by helicopters.

High-altitude plastic balloons are only partially inflated at launch to allow for gas expansion as the balloon climbs. This expansion is roughly tenfold for each 15,000 metres (50,000 feet) of altitude. When the balloon is at the designated altitude, the envelope takes on the natural shape—an inverted teardrop with the load attached at the bottom point. If the balloon were pressurized with no payload, the envelope would be spherical. There is a complete series of envelope shapes that depend on the ratio of payload-to-skin weight and internal pressure. Normally, the internal pressure is zero and the envelope weight is a high percentage of the total balloon weight. This gives a very fat balloon with an almost flat top. The included angle at the base can approach 45 degrees.

Some heavy-payload high-altitude balloons have been made of nylon laminated to polyester film, but most research balloons use very thin polyethylene. Some of these polyethylene films are less than a tenth of a millimetre thick. In order to carry a payload, the seams are reinforced with load-bearing tape.

In flight the payload is generally suspended from an open extended parachute connected at its apex to the base of the balloon. The parachute can be released by radio control. At the moment of release, the elasticity of the parachute snaps it open almost instantly. A radio-controlled gas valve can be used at the top of the balloon. Excess gas is vented by ducts high on the side of the balloon, with their openings at the base level. If the duct is placed high enough on the balloon, it is impossible for outside air to enter the balloon.

Contamination of the lifting gas by outside air will lower the possible ceiling of the balloon and, in the case of hydrogen, create a fire hazard. The design must assure that flow resistance in the duct does not create adverse back pressure, which would burst the balloon. The diameter of the duct, its length, and any possible kinks must be considered. The weight of the duct itself can pull it down enough to block the opening into the balloon in some cases. With the duct design, any entrained air from mishandling during inflation or minute leaks in the balloon below the base of the lifting gas will pool in the base of the balloon and lower the ceiling accordingly.

The natural shape gives a balloon very low skin stress under static conditions. At altitude the balloon is very stable and not generally subject to turbulence or dynamic loads. On the way up, the balloon is only partially inflated and has great flexibility to distort, relieving any stress.

The first manned stratosphere balloon used a spherical aluminum cabin. Following ones used magnesium alloys and spun aluminum. Current high-altitude pressure cabins are made with various composite materials. Internal pressure is maintained by onboard liquid oxygen supplies and air scrubbers to remove carbon dioxide, moisture, and other body products.

Several flights have been made with no cabin at all. Crews in open gondolas wear space suits similar to those that astronauts wear.

Long-distance ballooning

Flying for ever greater distances has always been a goal of balloonists. The first successful aerial crossing of the English Channel occurred on January 7, 1785, in a gas balloon piloted by French balloonist Jean-Pierre Blanchard and American balloonist John Jeffries. Another early long-distance flight was by the English balloonist Charles Green, accompanied by the Irish musician Thomas (“Monck”) Mason, aboard the Great Balloon of Nassau in November 1836. Taking off from London, they traveled about 750 km (480 miles) in 18 hours to land in the Duchy of Nassau (now in Germany). Paul (“Ed”) Yost and Donald Piccard made the first hot-air balloon crossing of the English Channel in 1963.

The New York Sun newspaper reported on April 13, 1844, that Monck Mason had made the first transatlantic balloon crossing, but the report turned out to be a hoax by Edgar Allan Poe. The actual first transatlantic balloon crossing occurred in 1978 aboard the Double Eagle II, a helium-filled balloon built by Yost, with piloting duties shared by three New Mexico businessmen, Ben L. Abruzzo, Maxie Anderson, and Larry M. Newman. The first transpacific balloon flight was made in 1981 by Americans Abruzzo, Newman, Ron Clark, and Rocky Aoki aboard the helium-filled Double Eagle V.

In 1987 British entrepreneur Richard Branson and Swedish aeronaut Per Lindstrand, aboard the Virgin Atlantic Flyer, made the first transatlantic flight in a hot-air balloon. And in 1991, aboard the Otsuka Flyer, they made the first transpacific flight in a hot-air balloon. In 1984 American aviator Joseph W. Kittinger, aboard the helium-filled Rosie O’Grady’s Balloon of Peace, made the first solo transatlantic balloon flight. In 1995 American adventurer Steve Fossett, aboard the helium-filled Solo Challenger, made the first solo transpacific balloon flight.

Several around-the-world balloon flights were attempted with various systems, but success was finally achieved in 1999 by Swiss balloonist Bertrand Piccard (son of Jacques Piccard, grandson of Auguste Piccard, and second cousin of Donald Piccard) and British balloonist Brian Jones aboard a combination hot-air and helium balloon, the Breitling Orbiter III, with a pressurized cabin. The first solo around-the-world balloon flight was made by Fossett aboard a combination helium and hot-air balloon, the Bud Light Spirit of Freedom, in 2002.

The success of the Breitling depended on several independent factors. Balloon design, cabin design, and meteorological technique were all unique and individually critical. While it may be possible to use other techniques, all manned major long-distance efforts have utilized the jet stream. This limits the altitude, track, and season for a successful attempt to the winter months in mid-latitudes at elevations of about 6,000 to 10,000 metres (about 20,000 to 35,000 feet).

In order to navigate a balloon on a long-distance flight, the pilot must take advantage of meteorological conditions. Sensitive attention to altitude, rate of climb, and global positioning instrumentation is essential in order to follow minute-by-minute advice from ground-based weather coaches. Information, including complete weather maps, can be communicated by wireless Internet e-mail connections. For an intercontinental flight, which may take several days, reevaluation of computer-generated weather predictions is important; for global circumnavigation it is essential.

For a successful global voyage only a general meteorological condition can be chosen. It is impossible to calculate weather conditions two and three weeks in advance at locations around the world. The general condition and the immediate forecast govern the decision to launch. Once the balloon is airborne and on its way, the weather model must be constantly updated and the balloon navigated precisely to take advantage of varying conditions. While the aeronauts of the 19th century had balloons that could theoretically cross the Atlantic, all attempts failed because they lacked the meteorology to make accurate predictions and the means to communicate predictions to the balloonist.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.


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