Miscellany

Jai Ganesh · 2020-04-24 01:26:25

531) Reinforced Cement Concrete

Advantages, Uses, Types, & Purpose.

Reinforced cement concrete (R.C.C) is the combination of ordinary concrete with the reinforcement to increase its compressive and tensile strength to a great extent.
Concrete is a versatile material for modern construction which is prepared by mixing well-proportioned quantities of cement (even lime in some cases), sand, crushed rock or gravel, and water.

It has been used from foundations to the rooftops of buildings, in the construction of highways roads traffic, and hydro-power tunnels, irrigation canals, drains, and all other conceivable structures.

Purpose of Reinforcement in Concrete.

As you know that, Concrete has a very high compressive strength, but it is low in tensile strength.

Thus, when only the compressive loads are acting on the concrete surface, then there is no need of using reinforcement in it.

But where tensile forces are also involved, as in, beams and slabs, there is a very high risk of its failure when plain concrete is used.

Steel, however, as we know, has a very high tensile strength (and also have good compressive strength).

Hence, when these two (concrete and steel) are combined together, a material of construction is obtained that is capable of withstanding all the three types of forces likely to act upon a structure, i.e., compressive loads, tensile stresses, and shear forces.

Such a material is known as Reinforced Cement Concrete.

It has proved extremely useful and reliable in engineering construction.

Nature of Reinforced Cement Concrete:

The main principle in the preparation of the reinforced cement concrete is to make a structural material in which

(i) Steel serves the purpose of bearing the main tensile stresses;
(ii) concrete bears the main compressive forces, both acting in complete unison;

Concrete and steel are compatible in following aspects:

(i) Concrete is basically alkaline in nature, (the principal component being Calcium hydroxide) and this prevents rusting of the steel reinforcement used within it;

(ii) The bond or ‘grip’ between the steel and concrete is established easily;

(iii) The coefficient of thermal expansion of concrete is almost identical with that of steel.

This prevents the risk of cracking due to expansion at different rates.

Types of Reinforcement used in R.C.C:

Reinforcement used in concrete is principally made of steel of different types.

Further, it may be made in required shape and volume.

Some common types of reinforcement are:

(i) Mild Steel Bars:

These come in various diameters and are required to possess a characteristic strength in tension which is specified in relevant codes.
This steel bar used as reinforcement can be commonly bent easily without cracking at the bends.

(ii) Hot Rolled Bars and Cold Worked Bars:

They are specially prepared reinforcements.
The first type has a characteristic strength in tension which is almost double than that of mild steel bars.
Further, as these come commonly in thick sections.
They can be bent by heating (up to 100°C) without developing any defects.
This is not possible with the ordinary mild steel bars.
Similarly, the cold worked steel bars come in twisted or stretched forms having elongated ribs or such structures along their length.
They also have a much higher characteristic strength of the order of 425 N/square mm against 250 N/square mm for mild steel bars.

Such bars may not be heated for bending and re-bending.

(iii) Steel Fabric:

This is made from a variety of bars and wires.
These may include plain round wires, indented and deformed wires, deformed steel bars of cold-worked type.
The mesh from such wires is made by welding together straightened lengths very carefully and strictly in accordance with the specifications.
Otherwise, the mechanical properties of reinforcement may be affected adversely.

Placement of Reinforcement:

It requires very complex and careful design considerations for each member of reinforcement concrete.

Thus, the size, shape, spacing, and location of reinforcement will be entirely different in a slab or beam or a column.

In beams, for example, steel bars may be required more in the lower sections and in fixed beams, in the end, sections as well where the tensile stresses are most effective.

The top section of the beam may need no reinforcement.
The horizontal reinforcements are often tied up with square stirrups at suitable intervals.
These stirrups also provide additional strength to the Reinforced Cement Concrete against shearing stresses.
The reinforcement requires the minimum prescribed covering of concrete.
The covering is essential to protect the reinforcement from deterioration under attack from weathering agencies and also from casual fires.
The concrete covering varies from 25 mm to 80 mm depending on the environment in which the RCC member has been placed.
It is also important that the reinforcement must be clear of rust, dust, and grease at the time of placement.
This will ensure a better bond between concrete and reinforcement.

Advantages of Reinforced Concrete : (RCC).

There are 100s of advantages of Reinforced Concrete, but here we will discuss some important advantages of Reinforced Concrete.

(i) Structures made from Reinforced Concrete are durable.
(ii) It has a high compressive strength (due to concrete).
(iii) It has a high tensile strength (due to reinforcement).
(iv) It is resistant to fire and other climate changes.
(v) Easily available almost anywhere in the world.
(vi) Too much expertise is not required for working on it, normal skilled labor can also do it.
(vii) It can be molded in any form, shape.
(viii) It can be used in any part of the structure i.e., from foundation to the top roofing.
(ix) Repairing cost is almost nil.
(x) It is more economical compared to other materials.

Jai Ganesh · 2020-04-25 00:57:08

532) Swallow

Swallow, any of the approximately 90 species of the bird family Hirundinidae (order Passeriformes). A few, including the bank swallow, are called martins. Swallows are small, with pointed narrow wings, short bills, and small weak feet; some species have forked tails. Plumage may be plain or marked with metallic blue or green; the genders look alike in most species.

Swallows spend much time in the air, capturing insects; they are among the most agile of passerine birds. For nesting, swallows may use a hole or cranny in a tree, burrow into a sandbank, or plaster mud onto a wall or ledge to house three to seven white, sometimes speckled, eggs.
Swallows occur worldwide except in the coldest regions and remotest islands. Temperate-zone species include long-distance migrants.

The common swallow (Hirundo rustica) is almost worldwide in migration; an American species, called barn swallow, may summer in Canada and winter in Argentina. The 10 species of Petrochelidon, which make flask-shaped mud nests, include the cliff swallow (P. pyrrhonota), the bird of San Juan Capistrano Mission, in California; as with other swallows, it has strong homing instincts.

Jai Ganesh · 2020-04-26 01:19:34

533) Viola (violet)

Viola, genus of about 500 species of herbs or low shrubs, including the small, solid-coloured violets and the larger-flowered, often multicoloured violas and pansies. Viola occur naturally worldwide but are found most abundantly in temperate climates, with the greatest variety occurring in the Andes Mountains of South America.

Wild Viola may be annuals or perennials. Because Viola freely hybridize, however, it is often difficult to identify their species. The flower, variable in colour, but not red, usually grows singly on a stalk and has five petals, four arranged in unlike pairs, the fifth with a spur. The leaves may grow on the same stalk as the flower (stemmed violets) or on separate stalks (stemless violets). Though the best-known Viola have heart-shaped leaves, the leaves of other species may have different shapes.

Typically, Viola grow in meadows or damp woods. All wild species bloom early in the spring, but some cultivated varieties bloom later. Many species have two types of flowers. One type is showy and appears in the spring but often does not produce seeds in some species. The fertile, less conspicuous flower appears in the early summer and is completely closed and self-fertilizing.

Among the most common North American species are the common blue, or meadow, violet (V. papilionacea) and the bird’s-foot violet (V. pedata). The common blue violet grows up to 20 cm (8 inches) tall and has heart-shaped leaves with finely toothed margins. The flowers range in colour from light to deep violet, or they may be white. The bird’s-foot violet, a perennial named for its deeply cleft leaves, has variably coloured flowers, with lilac and purple combinations.

Species of Viola have been widely cultivated in gardens and nurseries. The popular florist’s violets, consisting of several hybrids (many of them V. odorata) are usually called sweet violets.

The pansy is a hybrid that has been grown in gardens for centuries. The so-called African violet belongs not to Violaceae, in the order Malpighiales, but to Gesneriaceae, in the order Lamiales.

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Jai Ganesh · 2020-04-27 00:44:37

534) Chimney

Chimney, structure designed to carry off smoke from a fireplace or furnace. A chimney also induces and maintains a draft that provides air to the fire.

In western Europe before the 12th century, heating fires were almost invariably placed in the middle of a room, and chimneys were therefore rare. Most of the characteristic forms of modern chimneys originated in northern Europe, when masonry techniques were developed that allowed the construction of a hearth along a wall with a fireproof backstop and flue. Some medieval chimney stacks were tubular, and some had ingenious conical caps with hooded side vents to shield against rain. During the 15th and 16th centuries, tall chimneys elaborately decorated with carvings, niches, and inlays formed an important part of the architectural ensemble. As housing grew more commodious and many rooms in a single dwelling were equipped with fireplaces, flues were grouped to carry smoke to a central chimney of masonry. In English housing of this time, each flue emerging at the roof line was treated as a separate columnar structure with base, cap, and polygonal shaft, generally of elaborately shaped bricks. Chimneys of the 17th and 18th centuries tended to be rectangular and to have projecting top courses that formed protective caps. In North America a massive chimney of this type became the central feature of the colonial New England farmhouse. As coal was introduced for domestic heating, chimney construction became the subject of serious study, and in the late 18th century Sir Benjamin Thompson established the definitive forms and proper relationships of the chimney’s essential parts.

An ordinary domestic chimney consists of three parts: the throat, the smoke chamber, and the flue. The throat is the opening immediately above the fire; it usually narrows to a few inches in width just below the damper, a door that can be closed when the furnace or fireplace is not in use. Above the damper is the smoke chamber. At the bottom of the smoke chamber is a smoke shelf formed by setting back the masonry at the top of the throat to the line of the back wall of the flue; its function is to deflect downdrafts that might otherwise blow smoke out into the room. The smoke chamber narrows uniformly toward the top; it slows down drafts and acts as a reservoir for smoke trapped in the chimney by gusts across the chimney top. The flue, the main length of the chimney, is usually of masonry, often brick, and metal-lined. Vertical flues perform best, though a bend is sometimes included to reduce rain splash; bends are also necessary when several flues are united in a common outlet.

Industrial chimneys are usually free-standing single flues with cylindrical cores of firebrick and outer jackets of steel, brick, or reinforced concrete, often with an insulating air space between to allow for differential expansion. Because the taller the chimney, the better the draft, some industrial chimneys are more than 300 feet (91.5 m) in height.

Jai Ganesh · 2020-04-28 01:09:09

535) Pyorrhea

Pyorrhea, more popularly known as periodontitis, is one of the most widespread dental conditions for humans. This type of dental sickness occurs when the periodontium tissues that surround and support your teeth become compromised. When left untreated, pyorrhea can lead to you lose teeth or outright ending up losing teeth when push comes to shove. Tooth loss happens because you start losing the alveolar bone surrounding the teeth as your periodontium deteriorates.

It’s also important to note that before you get full-blown pyorrhea, you first end up with gingivitis and it gets worse from there. Once you have symptoms of this gum condition, you should treat it to avoid it worsening to periodontitis or some other form of periodontal disease.

Signs and Symptoms of Pyorrhea

There are no symptoms to pyorrhea in its initial stages. However, keep in mind that you’re already at risk if you have bad dental hygiene habits or tend to neglect your teeth cleanliness.

As the disease progresses from gingivitis, it starts showing major signs and symptoms you should pay attention to, such as the following.

• Bad breath
• Loose teeth
• Painful chewing
• Swollen or puffy gums
• Gums that bleed easily
• Bad breath or halitosis
• Recurrent gum swelling
• Pus between your teeth and gums
• Bright red, dusky red or purplish gums
• New spaces developing between your teeth
• Gums that feel tender or sensitive when touched
• A change in the way your teeth fit together when you bite
• Tooth or gum redness or bleeding when flossing or brushing
• Blood when you bite into hard fruits like pears, apples, or guava
• Deep pockets or spaces formed between the gums and the teeth
• Loose teeth that move in place when you touch it with your finger or tongue
• Gums that pull away from your teeth (recede), making your teeth look longer than normal

If these symptoms were to persist then you should consult your dentist or doctor ASAP. The more you ignore pyorrhea and allow it to progress the likelier you’ll get its most notable symptom, with is outright tooth loss.

Causes of Pyorrhea

Pyorrhea typically happens when you lack dental hygiene. It can also be hereditary in the case of aggressive pyorrhea or caused being immunocompromised, as in the case of cancer or HIV patients. Letting bacteria stick to your teeth in the form of filmy plaque or tartar will deteriorate your teeth from its enamel to its periodontium tissues.

At any rate, here are the most common causes of pyorrhea:

• Poor Dental Hygiene: Bacteria tend to spread if you don’t kill them with mouthwash that kills 99.9 percent of them or brush your teeth clean off all plaque and food bits. Flossing also helps a lot in scraping the plaque and the remnants of rotting food in between the spaces of your teeth. If you don’t brush and floss twice daily and mouthwash occasionally, you’re in for a rude awakening.
• Complacency and Neglect: Complacency is a slow but sure killer in and of itself. When you’re complacent with your dental habits to the point where the coating of plaque on your teeth has become tartar or seemingly enamel (it’s not, by the way), then that leads to dental destruction of the highest order. You don’t realize how neglect can affect your teeth and gums until it’s usually too late.
• Plaque and Tartar: When bad oral bacteria are allowed to run rampant in your mouth, they tend to form off-white or yellow film of protein and leftover food that’s teeming with germs called plaque. When this plaque hardens due to calcium deposits being put in the mix, it turns into calculus or tartar. The longer plaque stays on tooth enamel, the worse off your teeth and periodontium will become down the line.
• Periodontal Destruction: The disease is caused by the destruction of the periodontium tissue or the supportive tissue that keeps the teeth anchored to the gums and jawbone. Improper dental hygiene is what kills this tissue since that allows bacteria and their acidic waste products to proliferate. Bacterial populations should be kept low by ridding your mouth of leftover food, starch, and sugar and washing it with antiseptic mouthwash.
• Gingivitis or Mild Periodontal Disease: Great things start from small beginnings. Bad things too. Plaque left on your teeth can cause gingivitis, which is the mildest form of periodontal disease. This condition is defined as inflammation and irritation of the gum around the base of your teeth, which is also known as the gingiva. Gingivitis is reversible with good home oral care and professional dental treatment, as with periodontitis.
• Periodontitis or Severe Periodontal Disease: By failing to reverse gingivitis, it can worsen and develop all the way into pyorrhea or periodontitis. In other words, gingivitis can directly result into periodontitis, which causes pockets to develop between teeth and gums as your periodontium tissues die out. These pockets where the periodontium and gingiva used to be will then be filled with plaque, tartar, and (of course) bacteria.
• Diabetes and Pyorrhea: Certain conditions can cause other conditions to surface in your body. This is the case with diabetes and pyorrhea. If you have diabetes, your chances of also developing periodontitis also increase. Diabetics are often asked to observe dental hygiene to save themselves from further complications like dental disease.
• Smoking: Smoking tobacco is bad for you in many ways, including its impact on your dental health. Yes, there are links between smoking cigarettes and pyorrhea development. Continuing to smoke while your periodontitis is being treated also interferes with the treatment so you better get a nicotine patch and wean yourself from smoking altogether.

Types of Pyorrhea

Pyorrhea or periodontitis come in several variations or types. The thing they have in common is the fact that having them usually leads to bacteria eating away at your periodontium to the point where your teeth loses its anchors to your jaw, making it easier for them to loosen and fall off.
The most common types of pyorrhea include the following.

• Chronic Pyorrhea: The most common type of pyorrhea is the chronic kind. It affects mostly adults but it’s not unusual for children to suffer from this either. This condition is caused by plaque buildup that includes slow periodontal, gum, and bone deterioration that might get worse or improve over time depending on what the patient does about it.
• Aggressive Pyorrhea: Aggressive periodontitis typically starts at early adulthood or childhood and affects only a select number of the population. It’s a hereditary type of periodontal disease that affects families for the most part. If left untreated, this destructive pyorrhea type will cause rapid progression of tooth and bone loss when push comes to shove. It should be dealt with ASAP.
• Necrotizing Pyorrhea: Necrotizing periodontitis or periodontal disease is the worst type of pyorrhea that involves the death of supporting bone, tooth ligaments, and gum tissue caused by necrosis or lack of blood supply. This then results in severe infection. This condition usually occurs in people who have a suppressed immune system such as from cancer treatment, HIV infection, and so forth. It’s also caused by malnutrition.

Treatment of Pyorrhea

Periodontal disease or pyorrhea is curable but there is a point of no return you should be aware of with this disease. You might not be able to save some or all of your teeth if your pyorrhea is particularly bad, despite it being curable or reversible.

Long story short, you should brush and floss daily as well as gargle with mouthwash in order to keep bacterial populations low and your pyorrhea risk even lower. Here are important things to remember:
• Brushing: You should brush twice a day or even three times a day to avoid developing pyorrhea or any other kind of oral disease. You should also brush properly and don’t scrape too hard with your brush. Move the brush in a circular pattern and do it thoroughly but gently instead of roughly and shoddily. Brush at least 2-3 minutes daily and don’t forget to regularly change your toothbrush as well every 3-4 months.
• Flossing: Kids nowadays know flossing as a dance but these Millennials and Gen Z children should also be aware of how to properly floss in the dental sense. Many simply slip the floss between the teeth then pull it out in mere seconds, thinking they’re done. What they’re supposed to do is use a piece of floss on each individual tooth and then scrape not only the stuck bits of food but also the plaque on the tooth surface until all the teeth have been properly flossed.
• Mouthwash: Mouthwash is at least a bit more self-explanatory than flossing or brushing. Just gargle with the mouthwash and then spit it out, right? In certain situations, like when you have a bacterial infection or swelling infected gums, you might need to let that mouthwash stay in your mouth for at least 30 seconds before spitting it out. Ideally, you should use antiseptic mouthwash and use it after brushing and flossing. It also helps get rid of bad breath.
• Home-Made Remedies: You can also make use of home-made remedies to help fight or prevent pyorrhea. For example, you can chew an onion in order to kill germs that assist in periodontitis development. Onion also helps treat the bleeding gums symptom of both gingivitis and periodontal disease. You even have the option to eat fruits enriched with Vitamin C such as lemon and guava. Lemon prevents gum inflammation as well.
• Dentist Visit: You should regularly visit your dentist. This is important because he’s the one who’ll keep tabs on the healthiness of your gums. He can also do thorough cleaning of your teeth and gums that are even more effective than everyday brushing and flossing known as prophylaxis for at least every 6 months. Your dentist knows best and can provide the right treatment for your issues.
• Deep Cleaning: If you’re a patient with advanced pyorrhea and deep periodontal pockets where there used to be gum tissue, bone, and ligaments, you should avail of this treatment. It’s a package deal to treat chronic gum disease using the services of scaling and root planning.
• Scaling: This procedure involves the dentist removing tartar and plaque on your teeth, gums, and periodontal pockets. This buildup of yellowish and brownish material is directly causing your pyorrhea. Special debridement tools are needed to access these areas because they’re beyond the reach of flossing, tooth brushing, or prophylaxis treatments.
• Root Planing: The infected root is then smoothened out using dental instruments like a drill or a laser. The bacteria usually collects at the root and the pockets caused by your receding gumline, thus necessitating cleanup and removal. What’s more, infected tooth roots need to be planed in order to begin their healing.
• Aftercare: Your dentist will likely prescribe an over-the-counter (OTC) painkiller and antibiotic for your infection. He might also recommend follow-up visits to determine whether or not your deep-cleaned teeth require more scaling and root planning. These additional appointments also help him check the progress of your gingival and dental healing.

In Conclusion

Periodontal disease, like dental caries or tooth decay, is caused by neglect and not maintaining proper dental hygiene for the most part. Your food intake as well as whether you smoke and drink are also contributing factors. Therefore, observe proper dental hygiene and visit your dentist regularly. Keep him updated with your dental condition and what treatments you might need to prevent this sickness from happening or progressing.

If left untreated, pyorrhea can cause a lot of bone and tissue damage, to the point where you’ll outright lose teeth. You might end up having no choice but to wear dentures or get an expensive dental implant operation. Your immune system can also get quite strained when dealing with a chronic type of inflammation or infection, leading to extra complications if you’re not careful.

It’s also common sense to observe dental hygiene on top of getting periodontitis treatment from your dental professional because as always, an ounce of prevention will always trump a pound of cure.

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Jai Ganesh · 2020-04-29 00:42:52

536) Goat

Goat, any ruminant and hollow-horned mammal belonging to the genus Capra. Related to the sheep, the goat is lighter of build, has horns that arch backward, a short tail, and straighter hair. Male goats, called bucks or billys, usually have a beard. Females are called does or nannys, and immature goats are called kids. Wild goats include the ibex and markhor.

Domesticated goats are descended from the pasang (Capra aegagrus), which is probably native to Asia, the earliest records being Persian. In China, Great Britain, Europe, and North America, the domestic goat is primarily a milk producer, with a large portion of the milk being used to make cheese. One or two goats will supply sufficient milk for a family throughout the year and can be maintained in small quarters, where it would be uneconomical to keep a cow. For large-scale milk production, goats are inferior to cattle in the temperate zone but superior in the torrid and frigid zones. Goat flesh is edible, that from young kids being quite tender and more delicate in flavour than lamb, which it resembles. Some breeds, notably the Angora and Cashmere, are raised for their wool; young goats are the source of kid leather.

Angora goat

Angora goat, breed of domestic goat originating in ancient times in the district of Angora in Asia Minor. The goat’s silky coat yields the mohair of commerce. The Angora had been widely but unsuccessfully imported into Europe by the mid-18th century, but not until the animal was established in South Africa a century later did the Western mohair industry develop. Importation of the Angora goat to the United States followed shortly, with development centring in Texas and the Southwest.

The Angora is generally smaller than other domestic goats and sheep. Both males and females are horned, and the ears are long and drooping. The strong elastic fibre of the coat differs from wool primarily in its smoothness and lustre.

Boer

Boer, South African breed of goat, the most productive meat goat in the world. Millions of Boer goats are raised across southern Africa as well as in Australia and New Zealand, the United States and Canada, the United Kingdom, and elsewhere. They are prized for their size, rapid weight gain, carcass quality, hardiness, and docility. These qualities can be passed on even when Boer bucks are bred to does of other breeds. Boer does are renowned for kidding as often as two times in three years, frequently bearing twins and sometimes triplets.

Boer (Dutch: “farmer”) goats were bred by Afrikaner farmers who crossed various European and Indian breeds with breeds raised by Bantu and Khoekhoe people. In 1959, breeders in what is now Eastern Cape province founded the South African Boer Goat Breeders’ Association. This society has established the standards followed by breeders around the world. The most-prized Boer goats are large, stocky animals with a white body and a red head, brown eyes, lop (downward-hanging) ears, backward-curving horns, and strong, well-placed legs. Adult males often reach 160 kg (350 pounds), and females can weigh as much as 110 kg (about 250 pounds).

Cashmere

Cashmere, animal-hair fibre forming the downy undercoat of the Kashmir goat and belonging to the group of textile fibres called specialty hair fibres. Although the word cashmere is sometimes incorrectly applied to extremely soft wools, only the product of the Kashmir goat is true cashmere.

The fibre, known as pashm or pashmina in some parts of Asia, became known for its use in beautiful shawls and other handmade items produced in Kashmir, India. In the early 19th century cashmere shawls reached their greatest popularity, and the shawls of England, France, and the town of Paisley, Scot., were made to imitate the original Kashmir shawls.

The cashmere goat has a protective outer coat of coarse fibre that is 4 to 20 cm (1.5 to 8 inches) in length. The downy undercoat is made up of the fine, soft fibre commonly called cashmere, which ranges from 2.5 to 9 cm (1 to 3.5 inches) long. Most of this down fibre is plucked or combed out by hand during the molting season. Iranian cashmere, however, is obtained by shearing. The annual yield per animal ranges from a few grams to about 0.5 kilogram. A sweater requires the fleece of 4 to 6 goats; an overcoat uses the production of 30 to 40. Some fibre, called pulled cashmere, is taken from the skins of slaughtered animals.

The fleece is cleaned to remove such impurities as grease and vegetable matter. Coarse hairs are removed by various mechanical dehairing processes that are frequently kept secret by their developers. Processing reduces the final yield by about 50 percent. The amount of coarse hair remaining greatly affects price, with fibre having the lowest hair content commanding the highest price. High-quality cashmere-coating fabrics usually contain less than 5 percent of the coarse hair; fine-quality sweaters contain less than 1 percent. The scales forming the outer layer, or epidermis, of the fine fibre are less distinct than those of wool although more definite than in mohair; the cortical layer is striated and contains varying amounts of pigment that produce the fibre colour; and there is no distinct medulla (central canal). The fibres have diameters finer than those of the best wools. The Kashmir goats of China and Mongolia yield fibre with diameters ranging from 14.5 to 16.5 micrometres; that of Iranian goats is 17.5 to 19.5 micrometres. Colour, usually gray or tan, varies from white to black.

Fabric made of cashmere is warm and comfortable to the wearer, and it has excellent draping qualities and soft texture. The fibre, which absorbs and retains moisture much like wool, is somewhat weaker than fine wool and considerably weaker than mohair. It is highly susceptible to damage by strong alkalies and high temperatures. Dark fibres are bleached to obtain light shades, although the process may reduce strength and softness. Cashmere fabrics are subject to abrasion in wearing; pilling, or bunching together of surface fibres, is a problem in knitwear.

Cashmere is used mainly for fine coat, dress, and suit fabrics and for high-quality knitwear and hosiery. It is sometimes blended with other fibres. The strong, coarse hair separated from the down is used locally for grain bags, ropes, blankets, and tent curtains. Because world production is so small and gathering and processing are costly, cashmere is a luxury fibre. Demand and, consequently, price are affected by fashion trends. New man-made fibres with similar texture and fineness, produced at much lower cost, have become a source of competition.

The major producers of cashmere are China, Mongolia, and Iran. Cashmere is also produced on the Indian subcontinent and in Afghanistan and Turkey. The United States, the United Kingdom, and Japan are leading consumers.

LaMancha

LaMancha, American breed of dairy goat known for its much-reduced external ears. The lineage of LaManchas is uncertain; their relation to goats of the La Mancha region of Spain is not proven. The breed was developed in the early 20th century on the West Coast of the United States from unusually short-eared goats believed to be descended from goats brought to California by Spanish missionaries. Those goats were bred to several other breeds, including Nubians and Alpines, until a distinctive American LaMancha breed was developed. Official recognition by the American Dairy Goat Association came in 1958.

True-bred LaManchas must have one of only two distinct ear types: “gopher ears,” which may be up to 1 inch (2.5 cm) in length but preferably are nonexistent; or “elf ears,” which have a maximum length of 2 inches (5 cm). Only bucks with gopher ears are accepted for breeding, as bucks with elf ears may sire “throwback” kids with standard longer ears. The face must be long and straight; a curved nose of the Nubian type disqualifies a specimen from the show ring.

LaManchas have a short and glossy coat with numerous colour variations and patterns. They are considered a docile breed and are excellent producers of a milk that is high in fat and protein.

Nubian

Nubian, breed of goat, probably native to Africa but common also in India and the Middle East since ancient times. Imported Nubian goats figured prominently in crossbreeding with English varieties in the 19th century; the Anglo-Nubian was developed during this period.

Pendulous ears and a Roman nose are characteristic features of the Nubian, often described as an aristocratic animal. The goat’s short coat may be of any solid colour, parti-coloured, or spotted. Milk of the Nubian is higher in fat than that of most other goats.

Oberhasli

Oberhasli, breed of dairy goat from Switzerland, particularly Bern canton, where it is known as the Oberhasli-Brienzer. The most distinctive feature of the Oberhasli is its colour pattern, known as chamoisée. The short, glossy coat is a deep reddish bay broken by black markings on the muzzle and forehead, with a black stripe running down the back to the tail, a black belly, and black legs below the knees. Oberhaslis are occasionally born all black; of these, only the females are accepted as purebred.

Oberhaslis are medium-sized goats with long, upright ears, a straight nose, large eyes, and an alert appearance. The does are reliable milk producers, and the bucks and wethers (castrated males) have been used as pack animals because of their strength and sure-footedness. They have been bred in North America since the early 20th century, though for years they were categorized as Swiss Alpines and were often crossed with other Alpine breeds. In 1979, following a determined campaign of strict breeding, Oberhaslis were officially recognized as a distinct breed in North America.

Saanen

Saanen, popular breed of dairy goat originating in the Saanen Valley of Switzerland. The coat of the Saanen is fine and light-coloured, white being generally preferred. In build it is similar to the Toggenburg, with a medium-to-large frame, straight or dished face, and erect ears. The adult Saanen weighs roughly 65 kg (143 pounds). The milk of the Saanen, like that of other goats, is more easily digestible than cow’s milk. The breed is highly valued in Europe and the United States as an even, persistent producer.

Toggenburg

Toggenburg, breed of dairy goat originating in the Toggenburg valley of Switzerland. The oldest breed of dairy goat in the United States, the Toggenburg has proved widely adaptable. It is characterized by a comparatively small, solid-coloured body of any shade of brown, white ears with a dark central spot, two white stripes down the face, and predominantly white legs. As is that of other goats, milk of the Toggenburg is whiter and more easily digestible than cow’s milk.

Jai Ganesh · 2020-04-30 01:02:54

537) Aztec

Aztec, self name Culhua-Mexica, Nahuatl-speaking people who in the 15th and early 16th centuries ruled a large empire in what is now central and southern Mexico. The Aztecs are so called from Aztlán (“White Land”), an allusion to their origins, probably in northern Mexico. They were also called the Tenochca, from an eponymous ancestor, Tenoch, and the Mexica, probably from Metzliapán (“Moon Lake”), the mystical name for Lake Texcoco. From Tenochca was derived the name of their great city, Tenochtitlán, and from Mexica came the name for the city that superseded the Aztecs capital and for the surrounding valley, which was applied later to the whole Mexican nation. The Aztecs referred to themselves as Culhua-Mexica, to link themselves with Colhuacán, the centre of the most-civilized people of the Valley of Mexico.

The origin of the Aztec people is uncertain, but elements of their own tradition suggest that they were a tribe of hunters and gatherers on the northern Mexican plateau before their appearance in Mesoamerica in perhaps the 12th century CE; Aztlán, however, may be legendary. It is possible that their migration southward was part of a general movement of peoples that followed, or perhaps helped trigger, the collapse of the Toltec civilization. They settled on islands in Lake Texcoco and in 1325 founded Tenochtitlán, which remained their chief centre. The basis of Aztec success in creating a great state and ultimately an empire was their remarkable system of agriculture, which featured intensive cultivation of all available land, as well as elaborate systems of irrigation and reclamation of swampland. The high productivity gained by those methods made for a rich and populous state.

Under the ruler Itzcóatl (1428–40), Tenochtitlán formed alliances with the neighbouring states of Texcoco and Tlacopan and became the dominant power in central Mexico. Later, by commerce and conquest, Tenochtitlán came to rule an empire of 400 to 500 small states, comprising by 1519 some 5,000,000 to 6,000,000 people spread over 80,000 square miles (207,200 square km). At its height, Tenochtitlán itself covered more than 5 square miles (13 square km) and had upwards of 140,000 inhabitants, making it the most densely populated settlement ever achieved by a Mesoamerican civilization. The Aztec state was a despotism in which the military arm played a dominant role. Valour in war was, in fact, the surest path to advancement in Aztec society, which was caste- and class-divided but nonetheless vertically fluid. The priestly and bureaucratic classes were involved in the administration of the empire, while at the bottom of society were classes of serfs, indentured servants, and outright slaves.

Aztec religion was syncretistic, absorbing elements from many other Mesoamerican cultures. At base, it shared many of the cosmological beliefs of earlier peoples, notably the Maya, such as that the present earth was the last in a series of creations and that it occupied a position between systems of 13 heavens and 9 underworlds. Prominent in the Aztec pantheon were Huitzilopochtli, god of war; Tonatiuh, god of the sun; Tlaloc, god of rain; and Quetzalcóatl, the Feathered Serpent, who was part deity and part culture hero. Human sacrifice, particularly by offering a victim’s heart to Tonatiuh, was commonly practiced, as was bloodletting. Closely entwined with Aztec religion was the calendar, on which the elaborate round of rituals and ceremonies that occupied the priests was based. The Aztec calendar was the one common to much of Mesoamerica, and it comprised a solar year of 365 days and a sacred year of 260 days; the two yearly cycles running in parallel produced a larger cycle of 52 years.

The Aztec empire was still expanding, and its society still evolving, when its progress was halted in 1519 by the appearance of Spanish explorers. The ninth emperor, Montezuma II (reigned 1502–20), was taken prisoner by Hernán Cortés and died in custody. His successors, Cuitláhuac and Cuauhtémoc, were unable to stave off Cortés and his forces, and, with the Spanish capture of Tenochtitlán in 1521, the Aztec empire came to an end.

Jai Ganesh · 2020-05-01 01:18:45

538) Chicken

Chicken, (Gallus gallus), any of more than 60 breeds of medium-sized poultry that are primarily descended from the wild red jungle fowl (Gallus gallus, family Phasianidae, order Galliformes) of India. The chicken is perhaps the most widely domesticated fowl, raised worldwide for its meat and eggs.

Despite the chicken’s close relationship with the red jungle fowl, there is evidence that the gray jungle fowl (G. sonneratii) of southern India and other jungle fowl species, also members of Gallus, may have contributed to the bird’s ancestry. There is some debate about what the chicken’s scientific name should be. Although many taxonomists and ornithologists consider it as a domesticated form of the wild red jungle fowl, some classify it as a subspecies of the red jungle fowl (i.e., G. gallus domesticus), whereas others, including the U.S. Department of Agriculture, classify the bird as G. domesticus.

Natural History

Chickens have a squat and rounded appearance. They stand less than 70 cm (27.6 inches) tall and weigh approximately 2.6 kg (5.7 pounds) on average. Males (called roosters) and females (hens) are known for their fleshy combs, lobed wattles hanging below the bill, and high-arched tails. In some roosters, the tail can extend more than 30 cm (12 inches) in length.

Chickens breed in the spring and summer months. Egg laying is stimulated by the long stretches of daylight that occur during the warmer months; however, artificial lights placed in chicken coops can trigger a hen’s egg laying response throughout the year. The time between ovulation and egg-laying is approximately 23–26 hours. Subsequent ovulations may occur within an hour after the previous egg was laid, allowing some hens to produce as many as 300 eggs per year.

Fertilized embryos develop quickly, and chicks hatch approximately 21 days later. Chicks are born covered in down, but they mature quickly, becoming fully feathered after four to five weeks. At about six months, males produce viable male gamete, and females produce viable eggs. Members of free-ranging flocks may live for six to eight years under the best conditions, but most chickens used in the poultry industry serve as egg layers for two to three years before being slaughtered for their meat, with much of it being used in pet food. Chickens in captivity have been known to live for up to 30 years.

Social Hierarchy

Each flock of chickens develops a social hierarchy that determines access to food, nesting sites, mates, and other resources. A flock usually includes one dominant adult male, a few subdominant males, and two or more females that are carefully watched over by the dominant male. Social hierarchies in chickens are segregated by male/female and manifest as a pecking order, in which individuals of higher social rank may strike out at individuals of lower rank with their beaks (pecking) to ensure access to food and other resources. Altercations, however, may also include pummeling with wings and scratching with claws.

Chickens belonging to the same age cohort and males/females are often kept together in industrial production settings. The pecking order is established within groups of female chicks by the 10th week of life. In groups of male chicks, however, fights for dominance may continue into adulthood. In situations where one adult bird challenges another—which happens most often when a new bird is introduced into the flock—fights involving males risk injury and death more often than fights involving females.

Domestication And Economic Production

Chicken domestication likely occurred more than once in Southeast Asia and possibly India over the most recent 7,400 years, and the first domestications may have been for religious reasons or for the raising of fighting birds. Descendants of those domestications have spread throughout the world in several waves for at least the last 2,000 years. For most of that period, chickens were a common part of the livestock complement of farms and ranches throughout Eurasia and Africa. Only in the early 20th century, however, did chicken meat and eggs become mass-production commodities.

Modern high-volume poultry farms, with rows of cages stacked indoors for control of heat, light, and humidity, began to proliferate in Great Britain about 1920 and in the United States after World War II. Females (mature hens and younger chickens, called pullets) are raised for meat and for their edible eggs. Farmers have developed numerous breeds and varieties to fulfill commercial requirements.

Originally, meat production was a by-product of egg production. Only hens that could no longer produce enough eggs were killed and sold for meat. By the mid-20th century, however, meat production had outstripped egg production as a specialized industry. The market for chicken meat has grown dramatically since then, with worldwide exports reaching nearly 12.5 million metric tons (about 13.8 million tons) by the early 21st century.

Mature males have long been used for sport (now outlawed in many jurisdictions) as well as for breeding. Many immature males are castrated) to become meat birds (capons).

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Jai Ganesh · 2020-05-02 01:31:39

539) Amethyst

Amethyst, a transparent, coarse-grained variety of the silica mineral quartz that is valued as a semiprecious gem for its violet colour. Its physical properties are those of quartz, but it contains more iron oxide (Fe2O3) than any other variety of quartz, and experts believe that its colour arises from its iron content. Other theories attribute the colour to contained manganese or hydrocarbons. Heating removes the colour from amethyst or changes it to the yellow of citrine; most commercial citrine is made in this manner. Notable occurrences of amethyst include those in Brazil, Uruguay, Ontario, and North Carolina.

The name, derived from the Greek amethystos, “not intoxicated,” expresses the ancient folk belief that the stone protects its owner against drunkenness. In ancient writings the Latin name amethystus was used for amethyst, purple corundum, and purple garnet. Amethyst is the birthstone for February and is usually facetted with step cuts or emerald cuts, but it has been used for carved intaglios since ancient times. Amethyst is mentioned in the Bible (Exodus 28:19; 39:12) as one of the 12 stones adorning the breastplate (ḥoshen) of the high priests of Yahweh.

Jai Ganesh · 2020-05-02 18:50:31

540) McLeod gauge

A McLeod gauge is a scientific instrument used to measure very low pressures, down to (10)^{−6} Torr. It was invented in 1874 by Herbert McLeod (1841–1923). McLeod gauges were once commonly found attached to equipment that operates under vacuum, such as a lyophilizer. Today, however, these gauges have largely been replaced by electronic vacuum gauges.

The design of a McLeod gauge is somewhat similar to that of a mercury-column manometer. Typically it is filled with mercury. If used incorrectly, this mercury can escape and contaminate the vacuum system attached to the gauge.

McLeod gauges operate by taking in a sample volume of gas from a vacuum chamber, then compressing it by tilting and infilling with mercury. The pressure in this smaller volume is then measured by a mercury manometer, and knowing the compression ratio (the ratio of the initial and final volumes), the pressure of the original vacuum can be determined by applying Boyle's law.

This method is fairly accurate for non-condensible gases, such as oxygen and nitrogen. However, condensible gases, such as water vapour, ammonia, carbon dioxide, and pump-oil vapors may be in gaseous form in the low pressure of the vacuum chamber, but will condense when compressed by the McLeod gauge. The result is an erroneous reading, showing a pressure much lower than actually present. A cold trap may be used in conjunction with a McLeod gauge to condense these vapors before they enter the gauge.

The McLeod gauge has the advantage that it is simple to use and that its calibration is nearly the same for all non-condensable gases. The device can be manually operated and the scale read visually, or the process can be automated in various ways. For example, a small electric motor can periodically rotate the assembly to collect a gas sample. If a fine platinum wire is in the capillary tube, its resistance indicates the height of the mercury column around it.

Modern electronic vacuum gauges are simpler to use, less fragile, and do not present a mercury hazard, but their reading is highly dependent on the chemical nature of the gas being measured, and their calibration is unstable. For this reason, McLeod gauges continue to be used as a calibration standard for electronic gauges.

(In vacuum applications, a cold trap is a device that condenses all vapors except the permanent gases into a liquid or solid. The most common objective is to prevent vapors being evacuated from an experiment from entering a vacuum pump where they would condense and contaminate it. Particularly large cold traps are necessary when removing large amounts of liquid as in freeze drying.

Cold traps also refer to the application of cooled surfaces or baffles to prevent oil vapours from flowing from a pump and into a chamber. In such a case, a baffle or a section of pipe containing a number of cooled vanes, will be attached to the inlet of an existing pumping system. By cooling the baffle, either with a cryogen such as liquid nitrogen, or by use of an electrically driven Peltier element, oil vapour molecules that strike the baffle vanes will condense and thus be removed from the pumped cavity.)

Jai Ganesh · 2020-05-03 12:41:52

541) Jasmine

Jasmine, (genus Jasminum), also spelled jessamine, genus of about 200 species of fragrant-flowered shrubs and vines of the olive family (Oleaceae). The plants are native to tropical and to some temperate areas of the Old World. Several are cultivated as ornamentals.

Physical Description

Most true jasmines have climbing branches without tendrils. The white, yellow, or rarely pink flowers are tubular with a flaring, lobed, pinwheel-like form; some double-flowered varieties have been developed. The leaves can be evergreen or deciduous and usually are composed of two or more leaflets, although some species have simple leaves. The fruit in most species is a two-lobed black berry.

Major Species

Common jasmine, or poet’s jasmine (Jasminum officinale), native to Iran, produces fragrant white flowers that are the source of attar of jasmine used in perfumery. It is widely cultivated for its shining leaves and clusters of flowers that bloom in summer. Winter jasmine (J. nudiflorum), a Chinese species with solitary yellow flowers, is used as a cover plant on hillsides. Japanese, or primrose, jasmine (J. mesnyi) is a similar plant with larger flowers that bloom during the winter. Italian jasmine (J. humile), a vinelike shrub with yellow flowers, has many cultivated varieties. The fragrant dried flowers of Arabian jasmine (J. sambac) are used to make jasmine tea.

Other “Jasmines”

Many fragrant-flowered plants from other families are given the name jasmine, including the star, or Confederate, jasmine (Trachelospermum jasminoides), Cape jasmine (Gardenia jasminoides), Madagascar jasmine (Marsdenia floribunda), jasmine tobacco (Nicotiana alata), Carolina, or allspice, jasmine (Gelsemium sempervirens), Chilean jasmine (Mandevilla suaveolens), orange jasmine (various species of the genus Murraya), night or day jasmine (various species of Cestrum), and the crepe jasmine (Tabernaemontana divaricata).

Jai Ganesh · 2020-05-04 13:23:13

542) Electroencephalography

Electroencephalography, technique for recording and interpreting the electrical activity of the brain. The nerve cells of the brain generate electrical impulses that fluctuate rhythmically in distinct patterns. In 1929 German scientist Hans Berger published the results of the first study to employ an electroencephalograph, an instrument that measures and records these brain-wave patterns. The recording produced by such an instrument is called an electroencephalogram, commonly abbreviated EEG.

To record the electrical activity of the brain, 8 to 16 pairs of electrodes are attached to the scalp. Each pair of electrodes transmits a signal to one of several recording channels of the electroencephalograph. This signal consists of the difference in the voltage between the pair. The rhythmic fluctuation of this potential difference is shown as peaks and troughs on a line graph by the recording channel. The EEG of a normal adult in a fully conscious but relaxed state is made up of regularly recurring oscillating waves known as alpha waves. When a person is excited or startled, the alpha waves are replaced by low-voltage rapid irregular waves. During sleep, the brain waves become extremely slow. Such is also the case when a person is in a deep coma. Other abnormal conditions are associated with particular EEG patterns. For example, irregular slow waves known as delta waves arise from the vicinity of a localized area of brain damage.

Electroencephalography provides a means of studying how the brain works and of tracing connections between one part of the central nervous system and another. However, its effectiveness as a research tool is limited, because it records only a small sample of electrical activity from the surface of the brain. Many of the more complex functions of the brain, such as those that underlie emotions and thought, cannot be related closely to EEG patterns. Furthermore, the EEG is of no use in diagnosing psychiatric illness.

Electroencephalography has proved more useful as a diagnostic aid in cases of serious head injuries, brain tumours, cerebral infections, sleep disorders, epilepsy, and various degenerative diseases of the nervous system. Electroencephalography is also useful in the assessment of patients with suspected brain death. This is particularly important if organs are to be saved for transplantation as soon as brain death has been confirmed. Sleep deprivation and other provocative tests, including photic (light) stimulation and hyperventilation, can be used to accentuate borderline findings.

Jai Ganesh · 2020-05-06 00:02:08

543) Respiratory therapy

Respiratory therapy, also called respiratory care, medical profession primarily concerned with assisting respiratory function of individuals with severe acute or chronic lung disease.

One of the conditions frequently dealt with is obstruction of breathing passages, in which chest physiotherapy is used to facilitate clearing the airway of mucus or liquid secretion by suction. Chest percussion, performed manually or by means of a handheld percussor or vest, produces vibrations that help to loosen and mobilize secretions. Postural drainage is a technique in which the forces of gravity are used to promote the drainage of obstructing secretions.

Aerosol treatments are used to relieve bronchospasm and mucous membrane swelling and to mobilize secretions for easy removal. Water is a major therapeutic agent in bronchopulmonary disease and may be used in the form of cold steam, hot steam, or a fog (as in an oxygen tent or a croup tent). Aerosol humidifiers called nebulizers may be powered by compressor machinery or by a hand-squeezed bulb to project medication or water spray into the airway. Ultrasonic equipment may be used to propel very fine particles directly into the lungs, as in treatment of cystic fibrosis. Medications, such as bronchodilators, mucolytics, and antibiotics, can also be administered in an inhaled mist by means of an ultrasonic nebulizer.

Therapy may involve the administration of gases for inhalation. Oxygen may be administered in controlled amounts to assist laboured breathing. A mixture of helium and oxygen is used to treat some diseases of airway obstruction.

In addition, respiratory therapists are experts in the setup, adjustment, and maintenance of mechanical ventilators.

Jai Ganesh · 2020-05-07 01:05:17

544) Bougainvillea

Bougainvillea, (genus Bougainvillea), genus of about 18 species of shrubs, vines, or small trees, belonging to the four-o’clock family (Nyctaginaceae), native to South America. Many species are thorny. Only the woody vines have attained wide popularity; several species have produced very showy cultivated varieties, which are often grown indoors and in conservatories.

The inconspicuous flowers are surrounded by brightly coloured papery bracts, for which one species, B. glabra, from Brazil, is called paperflower; the bracts are purple or magenta to lighter tints in certain varieties. The stem of B. glabra may be 20 to 30 metres (about 60 to 100 feet) long in warm climates, and the plant is in flower throughout most of the year. The stem of B. spectabilis is covered with many short hairs, and the flowers are relatively short-lived. The combination of bract plus inconspicuous flower itself resembles a flower with conspicuous petals. B. peruviana, from Colombia to Peru, has rose to magenta bracts. B. × buttiana, a probable hybrid of B. glabra and B. peruviana, has given rise to varieties having lemon yellow (“Golden Glow”), orange (“Louis Wathen”), and crimson bracts. Bougainvilleas are hardy in warm climates.

Jai Ganesh · 2020-05-08 00:40:50

545) Chemotherapy

Chemotherapy, the treatment of diseases by chemical compounds. Chemotherapeutic drugs were originally those employed against infectious microbes, but the term has been broadened to include anticancer and other drugs.

Until the end of the 19th century, most drugs were derived either from minerals or from plants. The researches of Louis Pasteur in France and Robert Koch in Germany laid the foundations of bacteriology. It was Paul Ehrlich, however, who made the greatest contribution to the science (chemotherapy) he named. The problem facing medical scientists was to produce a disinfectant that would destroy parasites within a living animal without serious damage to the host.

William H. Perkin, in England, made the first aniline dye (1856) as a result of abortive attempts to synthesize quinine, the sole antimalarial drug available at that time. About 30 years later, Ehrlich found that a synthetic dye, methylene blue, has antimalarial properties. He had been led to this by a study of the specific staining of organs of an animal or of a parasite following the injection of a synthetic dye. From these studies there emerged (1901–04) Ehrlich’s well-known “side-chain” theory, in which he sought for the first time to correlate the chemical structure of a synthetic drug with its biological effects. In 1903 Ehrlich invented a dye, trypan red, which was the first drug to show activity against trypanosomal infections in mice. Ehrlich’s greatest triumph, however, was the discovery (1910) of the organic drug Salvarsan, which proved to be effective in the treatment of syphilis. The discovery of other chemotherapeutic agents followed, including mepacrine, proguanil, and chloroquine.
The discovery of Prontosil in the early 1930s proved that antibacterial agents could be developed. Prontosil was the forerunner of the sulfonamide drugs, which came to be widely used for the treatment of bacterial infections in humans and domestic animals.

The discovery of penicillin by Sir Alexander Fleming in 1928, and its practical development by Sir Howard Florey and Ernst Chain, marked another important advance in bacterial chemotherapy. Penicillin, which did not become widely used until World War II, was the first of the so-called antibiotics, and it was followed by other important antibiotics such as streptomycin, the tetracyclines, and the macrolides.

Antibiotics, whether they are produced by living organisms (usually fungi or bacteria) or artificially synthesized, have transformed the modern management of diseases caused by bacteria and most other microorganisms. Paradoxically, the more widely they are used, the greater the likelihood that drug-resistant bacteria will emerge. Bacteria may develop resistance to drugs in several ways: mutation changes in genetic composition; transduction, whereby resistance is transferred from a resistant to a nonresistant strain; transformation, in which a bacterial cell takes from its environment the genes from a resistant form to acquire resistance; and conjugation, in which the organism acquires resistance by cell-to-cell contact.

Another comparative failure of chemotherapy is the lack of drugs to combat viruses (although viral infections can be controlled through prophylactic measures).

Drug modes of action vary. For example, some may act on the bacterial wall, others affect cell membranes, some modify the molecular mechanism for duplication, some change the nucleic acid metabolism, and others change the intermediary metabolism of two interacting organisms.

Cancer chemotherapy is an increasingly important aspect of drug treatment. Alkylating agents (that work by impairing cell division) and antimetabolites (that interfere with enzymes and thus block vital cell processes) are used cytotoxically to attack malignant cells. Steroid hormones are used in the treatment of breast and prostate cancers, and corticosteroids are used to treat leukemia and lymphatic cancers. The periwinkle plant derivatives vincristine and vinblastine have been used effectively in treating Hodgkin’s disease and leukemia.

The alkylating agents and antimetabolites have serious drawbacks. As they cannot distinguish between healthy and malignant cells, these drugs also interfere with actively multiplying noncancerous cells. They also reduce the body’s resistance to infection. Work is being done on tumour-specific agents that attack only cancer cells.

Another area where chemotherapy has had a major, albeit controversial, impact is mental illness. Severe depression, anxiety, and schizophrenia are now treated with various drugs.

Concomitant with the successes of drug therapy has come increasing concern about attendant dangers. Stringent controls are operated by such regulatory agencies as the Food and Drug Administration in the United States and the Committee on Safety of Medicines in the United Kingdom. These bodies ensure the safety of pharmaceuticals before they are placed on the market and monitor any side effects thereafter. Public demands for “watchdog” agencies were triggered in large part by the 1962 Thalidomide tragedy, when thousands of severely deformed children were born to users of that insufficiently tested drug.

Jai Ganesh · 2020-05-09 01:09:43

546) Banjo

Banjo, stringed musical instrument of African origin, popularized in the United States by slaves in the 19th century, then exported to Europe. Several African stringed instruments have similar names—e.g., bania, banju. The banjo has a tambourine-like body with a hoop and a screw that secure the vellum belly to the frame. Screw stretchers are used to vary the tension of the belly. The strings pass over a violin-type, or pressure, bridge and are hitched to a tailpiece. In the 1890s, frets were added to the long neck, and a machine head with screws replaced the tuning pegs.

The earliest banjos had four gut strings; later, from five to nine metal strings were used. The standard banjo has five metal strings. Four are tuned from the head, usually to C′–G′–B′–D″ upward from (notated) middle C. Preceding the C string is the chanterelle (drone, or thumb), a shorter string fastened to a screw midway in the banjo neck. It is tuned to the (notated) second G above middle C. The actual pitch is an octave lower than notated.

Variants of the standard banjo abound. Banjos played with a plectrum, or pick, rather than fingers lack the chanterelle. On a zither banjo the vellum is suspended in a resonator that throws the sound forward; the chanterelle, tuned from the head, passes under the fingerboard to emerge at the fifth fret. The banjo is widely played in U.S. folk music and has also been used in jazz ensembles.

Jai Ganesh · 2020-05-10 00:39:32

547) Escalator

Escalator, moving staircase used as transportation between floors or levels in subways, buildings, and other mass pedestrian areas.

An inclined belt, invented by Jesse W. Reno of the United States in 1891, provided transportation for passengers riding on cleats attached to the belt, which was inclined at an angle of 25°; the handrail was stationary, but an improved version with a moving handrail was introduced the same year.

The name escalator was first applied to a moving stairway shown at the Paris Exposition of 1900. Originally a trademark of the Otis Elevator Company, the word was adjudged in 1949 to have become public property through popular use.

Modern escalators are usually inclined at 30°, limited in rise to about 60 feet (18 m), with floor-to-floor rise of about 12 feet (3.5 m). They are electrically powered, driven by chain and sprocket, and held in the proper plane by two tracks. As the treads approach the landing, they pass through a comb device; a deflection switch is actuated to cut off power if an object becomes jammed between the tread and the comb.

Escalators move at a rate of up to 120 feet (36 m) per minute; larger types have a capacity of 6,000 passengers per hour. If a chain breaks, the release of tension stops the escalator. A safety switch also halts the device if a handrail is broken or comes loose or if a side panel is deflected.

Moving ramps or sidewalks, sometimes called travelators, are specialized forms of escalators developed to carry people and materials horizontally or along slight inclines. Ramps may have either solid or jointed treads or a continuous belt. Ramps can move at any angle of up to 15°; beyond this incline the slope becomes too steep and escalators are favoured.

Jai Ganesh · 2020-05-11 01:24:35

548) Leukemia

Leukemia, a cancer of the blood-forming tissues characterized by a large increase in the numbers of white blood cells (leukocytes) in the circulation or bone marrow. A number of different leukemias are classified according to the course of the disease and the predominant type of white blood cell involved. Some types of leukemia have been related to radiation exposure, as noted in the Japanese population exposed to the first atomic bomb at Hiroshima; other evidence suggests hereditary susceptibility.

Leukemias are defined as either acute or chronic and as either myelogenous (from bone marrow) or lymphocytic (involving lymphocytes). These characteristics are used to designate almost all cases as one of four types—acute myelogenous, acute lymphocytic, chronic myelogenous, and chronic lymphocytic leukemia. Acute leukemias affect immature cells; the disease develops rapidly, with symptoms including anemia, fever, bleeding, and swelling of the lymph nodes. Immature leukemia cells continue to divide in the bone marrow, which leads to rapid death if left untreated. In chronic leukemia the cells develop and are transported to the tissues, but the cells do not function normally. Myelogenous leukemia affects granulocytes and monocytes, white blood cells that destroy bacteria and some parasites.

The most common form in children, acute lymphocytic leukemia, once killed more than 90 percent of its victims within six months. With new drug therapies, the majority of acute lymphocytic patients now achieve complete remission, with no evidence of malignant cells in the blood. With continued therapy, more than half remain free of disease for five years or longer. These patients are presumed to be cured.

Results of treatment for other leukemias have not been as positive. In acute myelogenous leukemia, which is more common in adults, patients can experience complete remission, but recurrence is common. Chronic leukemias also occur more frequently in adults. These are characterized by a more gradual onset and a more protracted course. Chronic myelogenous leukemia (CML), which has a peak incidence among adults in their 40s, may remain quiescent for long periods before symptoms such as weight loss, low fever, and weakness develop. Left untreated, CML may culminate in a fatal phase known as a blast crisis, which occurs when one-fifth to one-third of the cells in the blood or bone marrow are immature blood cells, or blast cells. This phase of CML can last four to six months and is characterized by fever, weakness, and an enlarged spleen.

Chronic lymphocytic leukemia occurs primarily in elderly people and may be inactive for months or years. The leukemia itself is rarely the cause of death, but it renders the patient vulnerable to infection or hemorrhage.

Jai Ganesh · 2020-05-12 00:47:37

549) Maya

Maya, Mesoamerican Indians occupying a nearly continuous territory in southern Mexico, Guatemala, and northern Belize. In the early 21st century some 30 Mayan languages were spoken by more than five million people, most of whom were bilingual in Spanish. Before the Spanish conquest of Mexico and Central America, the Maya possessed one of the greatest civilizations of the Western Hemisphere. They practiced agriculture, built great stone buildings and pyramid temples, worked gold and copper, and used a form of hieroglyphic writing that has now largely been deciphered.

As early as 1500 BCE the Maya had settled in villages and had developed an agriculture based on the cultivation of corn (maize), beans, and squash; by 600 CE cassava (sweet manioc) was also grown. (See also origins of agriculture: Early development: The Americas.) They began to build ceremonial centres, and by 200 CE these had developed into cities containing temples, pyramids, palaces, courts for playing ball, and plazas. The ancient Maya quarried immense quantities of building stone (usually limestone), which they cut by using harder stones such as chert. They practiced mainly slash-and-burn agriculture, but they used advanced techniques of irrigation and terracing. They also developed a system of hieroglyphic writing and highly sophisticated calendrical and astronomical systems. The Maya made paper from the inner bark of wild fig trees and wrote their hieroglyphs on books made from this paper. Those books are called codices. The Maya also developed an elaborate and beautiful tradition of sculpture and relief carving. Architectural works and stone inscriptions and reliefs are the chief sources of knowledge about the early Maya. Early Mayan culture showed the influence of the earlier Olmec civilization.

The rise of the Maya began about 250 CE, and what is known to archaeologists as the Classic Period of Mayan culture lasted until about 900 CE. At its height, Mayan civilization consisted of more than 40 cities, each with a population between 5,000 and 50,000. Among the principal cities were Tikal, Uaxactún, Copán, Bonampak, Dos Pilas, Calakmul, Palenque, and Río Bec. The peak Mayan population may have reached two million people, most of whom were settled in the lowlands of what is now Guatemala. After 900 CE, however, the Classic Maya civilization declined precipitously, leaving the great cities and ceremonial centres vacant and overgrown with jungle vegetation. Some scholars have suggested that armed conflicts and the exhaustion of agricultural land were responsible for the sudden decline. Discoveries in the 21st century led scholars to posit a number of additional reasons for the destruction of Mayan civilization. One cause was probably the war-related disruption of river and land trade routes. Other contributors may have been deforestation and drought. During the Post-Classic Period (900–1519), cities such as Chichén Itzá, Uxmal, and Mayapán in the Yucatán Peninsula continued to flourish for several centuries after the great lowland cities had become depopulated. By the time the Spaniards conquered the area in the early 16th century, most of the Maya had become village-dwelling agriculturists who practiced the religious rites of their forebears.

The major extant Mayan cities and ceremonial centres feature a variety of pyramidal temples or palaces overlain with limestone blocks and richly ornamented with narrative, ceremonial, and astronomical reliefs and inscriptions that have ensured the stature of Mayan art as premier among Native American cultures. But the true nature of Mayan society, the meaning of its hieroglyphics, and the chronicle of its history remained unknown to scholars for centuries after the Spaniards discovered the ancient Mayan building sites.

Systematic explorations of Mayan sites were first undertaken in the 1830s, and a small portion of the writing system was deciphered in the early and mid-20th century. Those discoveries shed some light on Mayan religion, which was based on a pantheon of nature gods, including those of the Sun, the Moon, rain, and corn. A priestly class was responsible for an elaborate cycle of rituals and ceremonies. Closely related to Mayan religion—indeed, inextricable from it—was the impressive development of mathematics and astronomy. In mathematics, positional notation and the use of the zero represented a pinnacle of intellectual achievement. Mayan astronomy underlay a complex calendrical system involving an accurately determined solar year (18 months of 20 days each, plus a 5-day period considered unlucky by the Mayans), a sacred calendar of 260 days (13 cycles of 20 named days), and a variety of longer cycles culminating in the Long Count, a continuous marking of time, based on a zero date in 3113 BCE. Mayan astronomers compiled precise tables of positions for the Moon and Venus and were able to accurately predict solar eclipses.

On the basis of these discoveries, scholars in the mid-20th century mistakenly thought that Mayan society was composed of a priestly class of peaceful stargazers and calendar keepers supported by a devout peasantry. The Maya were thought to be utterly absorbed in their religious and cultural pursuits, in favourable contrast to the more warlike and sanguinary indigenous empires of central Mexico. But the progressive decipherment of nearly all of the Mayan hieroglyphic writing has provided a truer if less-elevating picture of Mayan society and culture. Many of the hieroglyphs depict the histories of the Mayan dynastic rulers, who waged war on rival Mayan cities and took their aristocrats captive. Those captives were then tortured, mutilated, and sacrificed to the gods. Indeed, torture and human sacrifice were fundamental religious rituals of Mayan society; they were thought to guarantee fertility, demonstrate piety, and propitiate the gods, and, if such practices were neglected, cosmic disorder and chaos were thought to result. The drawing of human blood was thought to nourish the gods and was thus necessary for achieving contact with them; hence, the Mayan rulers, as the intermediaries between the Mayan people and the gods, had to undergo ritual bloodletting and self-torture.

The present-day Mayan peoples can be divided on linguistic and geographic grounds into the following groups: the Yucatec Maya, inhabiting Mexico’s Yucatán Peninsula and extending into northern Belize and northeastern Guatemala; the Lacandón, very few in number, occupying a territory in southern Mexico between the Usumacinta River and the Guatemalan border, with small numbers in Guatemala and Belize; the K’ichean-speaking peoples of the eastern and central highlands of Guatemala (Q’eqchi’, Poqomchi’, Poqomam, Uspanteko, K’iche’, Kaqchikel, Tz’utujil, Sakapulteko [Sacapultec], and Sipacapa [Sipacapeño]); the Mamean peoples of the western Guatemalan highlands (Mam, Teco [Tektiteko], Awakateko, and Ixil); the Q’anjobalan peoples of Huehuetenango and adjacent parts of Mexico (Motocintlec [Mocho’], Tuzantec, Jakalteko, Akateko, Tojolabal, and Chuj); the Tzotzil and Tzeltal peoples of Chiapas in southern Mexico; the Cholan peoples, including the Chontal and Chol speakers in northern Chiapas and Tabasco and the linguistically related Chortí of the extreme eastern part of Guatemala; and the Huastec of northern Veracruz and adjoining San Luís Potosí in east-central Mexico. The chief division in Mayan cultural types is between highland and lowland cultures. Yucatec, Lacandón, and Chontal-Chol are lowland groups. The Huastec, a linguistically and geographically separated group living in Veracruz and San Luis Potosí, who never were Mayan culturally, and the other Mayan peoples live in highlands across Guatemala.

Contemporary Maya are basically agricultural, raising crops of corn, beans, and squash. They live in communities organized around central villages, which may be permanently occupied but more commonly are community centres with public buildings and houses that generally stand vacant; the people of the community live on farm homesteads except during fiestas and markets. Dress is largely traditional, particularly for women; men are more likely to wear modern ready-made clothing.
Domestic spinning and weaving, once common, are becoming rare, and most clothing is made of factory-woven cloth. Cultivation is with the hoe and, where the soil is tough, the digging stick. The Yucatec usually keep pigs and chickens and, rarely, oxen that are used for farming. Industries are few, and crafts are oriented toward domestic needs. Usually some cash crop or item of local manufacture is produced for sale outside the region in order to provide cash for items not otherwise obtainable.

Most Maya are nominal Roman Catholics—though, beginning in the late 20th century, many converted to Evangelical Protestantism. Their Christianity, however, is generally overlaid upon the native religion. Its cosmology is typically Mayan, and Christian figures are commonly identified with Mayan deities. Public religion is basically Christian, with masses and saint’s day celebrations. The native pre-Columbian religion is observed in domestic rites.

Jai Ganesh · 2020-05-13 01:40:36

550) Spondylitis

Spondylitis, inflammation of one or more of the vertebrae. Spondylitis takes several forms; the most widely occurring forms are ankylosing spondylitis, hypertrophic spondylitis, and tuberculous spondylitis.

Ankylosing spondylitis (also called Bekhterev spondylitis, deforming spondylitis, or Marie-Strümpell arthritis) is a disease of the spine that is characteristically seen chiefly in adolescent boys and young men. Its earliest symptom is chronic lower back pain. The progression of the disease can be noted in stiffness and limitation of movement, swollen joints (often indistinguishable from rheumatoid arthritis), fusion (ankylosis) and deformity of the spine, and anemia. Treatment is similar to that for rheumatoid arthritis and may include the use of nonsteroidal anti-inflammatory drugs.

Hypertrophic spondylitis, also known as osteoarthritis of the spine, is a degenerative disease seen mostly in individuals over the age of 50. It is characterized by the destruction of intervertebral disks and the growth of spurs on the vertebrae themselves. Treatment includes rest, the application of heat, and exercises to maintain a normal range of movement.

Tuberculous spondylitis (also called tuberculosis of the spine) is caused by infection of the vertebral column by the tuberculosis bacillus, Mycobacterium tuberculosis.

Pott disease

Pott disease, also called tuberculous spondylitis or tuberculosis of the spine, disease caused by infection of the spinal column, or vertebral column, by the tuberculosis bacillus, Mycobacterium tuberculosis. Pott disease is characterized by softening and collapse of the vertebrae, often resulting in a hunchback curvature of the spine. The condition is named after an English surgeon, Sir Percivall Pott, who described it in a monograph published in 1779. The infection begins in the body of the vertebra (the most common site of bone tuberculosis) and spreads slowly to contiguous structures. Abscesses may form and drain into soft tissues adjacent to the spine, causing pain in sites distant from the infection. Occasionally the spinal nerves are affected, and paralysis may result. Affected persons complain of pain on movement and tend to assume a protective, stiff position. The course of the disease is slow, lasting months or years. Treatment includes chemotherapy against the M. tuberculosis bacillus and orthopedic care of the spinal column. Modern treatment has made Pott disease rare in developed countries, but in less-developed countries it still accounts for up to 2 percent of all tuberculosis cases and particularly affects children.

Jai Ganesh · 2020-05-14 01:17:47

551) Sumer

Sumer was an ancient civilization founded in the Mesopotamia region of the Fertile Crescent situated between the Tigris and Euphrates rivers. Known for their innovations in language, governance, architecture and more, Sumerians are considered the creators of civilization as modern humans understand it. Their control of the region lasted for short of 2,000 years before the Babylonians took charge in 2004 B.C.

Sumerian Civilization

Sumer was first settled by humans from 4500 to 4000 B.C., though it is probable that some settlers arrived much earlier.

This early population—known as the Ubaid people—was notable for strides in the development of civilization such as farming and raising cattle, weaving textiles, working with carpentry and pottery and even enjoying beer. Villages and towns were built around Ubaid farming communities.

The people known as Sumerians were in control of the area by 3000 B.C. Their culture was comprised of a group of city-states, including Eridu, Nippur, Lagash, Kish, Ur and the very first true city, Uruk. At its peak around 2800 BC, the city had a population between 40,000 and 80,000 people living between its six miles of defensive walls, making it a contender for the largest city in the world.

Each city-state of Sumer was surrounded by a wall, with villages settled just outside and distinguished by the worship of local deities.

Sumerian Language And Literature

The Sumerian language is the oldest linguistic record. It first appeared in archaeological records around 3100 B.C. and dominated Mesopotamia for the next thousand years. It was mostly replaced by Akkadian around 2000 B.C. but held on as a written language in cuneiform for another 2,000 years.

Cuneiform, which is used in pictographic tablets, appeared as far back as 4000 B.C., but was later adapted into Akkadian, and expanded even further outside of Mesopotamia beginning in 3000 B.C.

Writing remains one of the most important cultural achievements of the Sumerians, allowing for meticulous record keeping from rulers down to farmers and ranchers. The oldest written laws date back to 2400 B.C. in the city of Ebla, where the Code of Er-Nammu was written on tablets.

The Sumerians were considered to have a rich body of literary works, though only fragments of these documents exist.

Sumerian Art and Architecture

Architecture on a grand scale is generally credited to have begun under the Sumerians, with religious structures dating back to 3400 B.C., although it appears that the basics of the structures began in the Ubaid period as far back as 5200 B.C. and were improved upon through the centuries. Homes were made from mud bricks or bundled marsh reeds. The buildings are noted for their arched doorways and flat roofs.

Elaborate construction, such as terra cotta ornamentation with bronze accents, complicated mosaics, imposing brick columns and sophisticated mural paintings all reveal the society’s technical sophistication.

Sculpture was used mainly to adorn temples and offer some of the earliest examples of human artists seeking to achieve some form of naturalism in their figures. Facing a scarcity of stone, Sumerians made leaps in metal-casting for their sculpture work, though relief carving in stone was a popular art form.

Under the Akkadian dynasty, sculpture reached new heights, as evidenced by intricate and stylized work in diorite dated to 2100 B.C.

Ziggurats began to appear around 2200 B.C. These impressive pyramid-like, stepped temples, which were either square or rectangular, featured no inner chambers and stood about 170 feet high. Ziggurats often featured sloping sides and terraces with gardens. The Hanging Gardens of Babylon was one of these.

Palaces also reach a new level of grandiosity. In Mari around 1779 B.C., an ambitious 200-room palace was constructed.

Sumerian Science

Sumerians had a system of medicine that was based in magic and herbalism, but they were also familiar with processes of removing chemical parts from natural substances. They are considered to have had an advanced knowledge of anatomy, and surgical instruments have been found in archeological sites.

One of the Sumerians greatest advances was in the area of hydraulic engineering. Early in their history they created a system of ditches to control flooding, and were also the inventors of irrigation, harnessing the power of the Tigris and Euphrates for farming. Canals were consistently maintained from dynasty to dynasty.

Their skill at engineering and architecture both point to the sophistication of their understanding of math. The structure of modern time keeping, with sixty seconds in a minute and sixty minutes in an hour, is attributed to the Sumerians.

Sumerian Culture

Schools were common in Sumerian culture, marking the world’s first mass effort to pass along knowledge in order to keep a society running and building on itself.
Sumerians left behind scores of written records, but they are more renowned for their epic poetry, which influenced later works in Greece and Rome and sections of the Bible, most notably the story of the Great Flood, the Garden of Eden, and the Tower of Babel. The Sumerians were musically inclined and a Sumerian hymn, “Hurrian Hymn No. 6,” is considered the world’s oldest musically notated song.

Gilgamesh

The very first ruling body of Sumer that has historical verification is the First Dynasty of Kish. The earliest ruler mentioned is Etana of Kish, who, in a document from the time, is credited as having “stabilized all the lands.” One thousand years later, Etana would be memorialized in a poem that told of his adventures in heaven.

The most famous of the early Sumerian rulers is Gilgamesh, king of Uruk, who took control around 2700 B.C. and is still remembered for his fictional adventures in the ‘Epic of Gilgamesh’, the first epic poem in history and inspiration for later Roman and Greek myths and Biblical stories.

A devastating flood in the region was used as a pivotal point in the epic poem and later reused in the Old Testament story of Noah.

Sumerian Power Struggles

Somewhere around 2600 B.C., a power struggle erupted between the leaders of Kish, Erech and Ur, which set off a “musical-chairs” scenario of rulers for the region for the next 400 years.

The first conflict resulted in the kingdom of Awan seizing control and shifting the ruling body outside of Sumer until the kingship was returned to the Kish.
The Kish kept control briefly until the rise of Uruk King Enshakushanna, whose brief dynasty was followed by Adabian conqueror Lugalannemundu, who held power for 90 years and is said to have expanded his kingdom up to the Mediterranean. Lugalannemundu also conquered the Gutian people, who lived in the Eastern Iraqi mountains and who would later come to rule Sumer.

In 2500 B.C. the only woman to rule the Sumerians, Kubaba, took the throne. She is the only female listed on the Sumerian King List, which names all rulers of Sumer and their accomplishments. Kubaba’s son, Puzur-Suen, eventually reigned, bringing in the fourth dynasty of Kish, following a brief ascendency of Unzi, the first in the Akshak Dynasty.

This last Kish dynasty ruled for a century before Uruk king Lugal-zage-si ruled for 25 years before Sargon took control in 2234.

Sargon

Sargon was an Akkadian whose past is shrouded in legends that some claim were ignited by Sargon himself. The claim is that he was the secret child of a high priestess who placed him in a basket and cast him off into a river, a story that was later utilized for Moses in the Old Testament.

Sumerian tradition says that Sargon was the son of a gardener who rose to the position of cupbearer for Ur-Zababa, king of Kish, which was not a servant position but a high official.

Ur-Zababa was defeated by the king of Uruk, who was, in turn, overtaken by Sargon. Sargon followed that victory by seizing the cities of Ur, Umma and Lagash, and establishing himself as ruler. His militaristic reign reached to the Persian Gulf.

Sargon built the city of Agade as his base, south of Kish, which became an important center in the ancient world and a prominent port. Agade was also home to Sargon’s army, which is considered the first organized standing army in history and the earliest to use chariots in warfare.

Sargon took control of the religious cultures of the Akkadians and the Sumerians, making his daughter Enhedu-anna the head priestess of the moon god cult of Ur. Enheduanna is best remembered for her transcriptions of temple hymns, which she also wrote and preserved in her writings.

Sargon ruled for 50 years, and after his death, his son Rimush faced widespread rebellion and was killed. Rimush’s brother Manishtushu met the same fate.
Sargon’s grandson, Naram-Sin, took the throne in 2292 B.C. Naram-Sin considered himself divine and was leveled with charges of sacrilege.

The Gutians invaded in 2193 B.C. following the reign of the last Akkadian king, Naram-Sin’s son Sharkalisharri. Their era is marked by decentralized chaos and neglect. It was during Gutian reign that the grand city of Agade decayed into wreckage and disappeared from history.

Ur-Nammu

The final gasp of Sumer leadership came in 2100 B.C. when Utuhegal, king of Ur, overthrew the Gutians. Utuhegal’s reign was brief, with Ur-Nammu, the former governor of Ur, taking the throne, starting a dynasty that would rule for about a century.

Ur-Nammu was known as a builder. Figurines from the time depict him carrying building materials. During his reign, he started massive projects to build walls around his capital city, to create more irrigation canals, construct new temples and rebuild old ones.

Ur-Nammu also did the considerable work of constructing an organized and complicated legal code that is considered the first in history. Its purpose was to ensure that everyone in the kingdom, no matter what city they lived in, received the same justice and punishments, rather than rely on the whims of individual governors.

Ur-Nammu also created an organized school system for state administrators. Called the Edubba, it kept an archive of clay tablets for learning.

What Happened to Sumer?

In 2004 B.C., the Elamites stormed Ur and took control. At the same time, Amorites had begun overtaking the Sumerian population.

The ruling Elamites were eventually absorbed into Amorite culture, becoming the Babylonians and marking the end of the Sumerians as a distinct body from the rest of Mesopotamia.

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Jai Ganesh · 2020-05-15 01:40:10

552) Anise seed

Anise seeds lend a licorice flavor to baked goods and more. This spice is widely used in Middle Eastern, Italian, German, Indian, and Mexican cooking. Anise seed is used in Italian biscotti, desserts, and charcuterie. Its extract flavors alcohol including anisette and ouzo.

What Is Anise?

Anise seed is used as a spice, either ground or whole. Anise essential oil and extract are also made from the seeds. The seeds are produced by the Pimpinella anisum plant, which has been cultivated in Egypt, the Middle East, and Europe for many centuries. The seeds are small, brownish-gray, and slightly curved, with an aroma of licorice. The plant also has aromatic leaves and stems that can be used as an herb, tasting like licorice, fennel or tarragon.

Anise vs. Star Anise vs. Fennel

Despite its similar name, anise is not related to star anise (Illicium verum), which is another spice from a different family of plants. Either can be used to make anise extract as both contain anethole, which produces the characteristic anise flavor. Anise (Pimpinella anisum) is the source of the extract and seeds used in European, Mediterranean, and Middle Eastern cuisine. The star anise is native to China. As star anise is cheaper to produce, today much of the essential oil of anise is from star anise rather than anise.

Star Anise, Not to Be Confused With Anise Seed

Anise is not the same thing as fennel, although the two do have a similar flavor, and the plants are somewhat similar looking. Anise and fennel are from the same family of plants (along with caraway, parsley, cilantro, and others), but they are different species. In general, fennel is served as a vegetable, while anise is used as a spice in seed form, either whole or ground.

What Does It Taste Like?

Anise has a licorice flavor that is sweet, mildly spicy, and very aromatic. This flavor is produced by anethole, an organic compound related to estragole, which produces flavors in tarragon and basil. One key characteristic of anethole is that it is very soluble in alcohol but only slightly soluble in water. As a result, when you add water to liqueurs that contain anise extract, the drink turns cloudy. This is known as the ouzo effect after one of the characteristic anise-flavored liqueurs.

Cooking

Anise seed (whole or ground) can be added to the dough for baked goods, fruit fillings for pies, and ground meat before baking. Anise extract can be used in baked goods and to flavor drinks such as coffee or hot chocolate. The seeds can also be used to brew a licorice-flavored tea.

Anise seed is the flavoring for a number of alcoholic beverages, including anisette, ouzo, sambuca, and absinthe. The slight candy-like flavor has made them popular as after dinner or dessert drinks. They can also be used to add flavor to coffee.

Recipes

You will find anise seed and its extract used in baked goods, savory dishes, and drinks in both the Old World and the New World. A few good ones are Pan Chuta sweet anise bread, double anise biscotti, and anise cinnamon sugar cookies.

Substitutions

If you don't have anise seed available for a recipe, the best substitution would be fennel seed, a few drops of anise extract, or star anise. Any of these would add the licorice flavor. If you have whole star anise, it should be ground before using if it's going to remain in the finished food, as it is woody and can't be chewed.

Buying Tips

Look for ground and whole anise seed in the spice section of the supermarket. It is sold in small jars similarly to nutmeg, cinnamon, and cloves. Anise extract may be found in the baking section, sold in small bottles.

How to Make Your Own Anise Extract

If you have anise seeds, vodka, and a small jar, you can make anise extract. Then you can use it for making biscotti or add it to a shot of espresso for some extra gusto.
1. Sterilize a 4-ounce jar.
2. Add 1 teaspoon of anise seeds to the jar, then 1/2 cup of vodka.
3. Seal the jar tightly and store it someplace cool and dark for two to three months.
4. Then strain out the seeds by pouring it through cheesecloth into another bottle or jar.
5. Store in a cool, dark place. The extract should be good for up to five years.

Storage

Whole or ground anise seed should be stored in a cool, dark place for the best shelf life. The whole seeds will be of the best quality for three to four years. Ground anise seed will lose its potency faster but still be good to use.

Benefits

Anise seeds are regarded as assisting digestion and helping prevent intestinal gas and flatulence. In India, anise seed is often offered to chew after the meal. Because it can have estrogen-like effects, it is being investigated for various uses as a supplement. But that could have a negative effect by stimulating hormone-dependent tumors and endometriosis, so caution is needed.

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Jai Ganesh · 2020-05-16 00:39:25

553) Chrysanthemum

Chrysanthemum, (genus Chrysanthemum), genus of about 40 species of flowering plants in the aster family (Asteraceae), native primarily to subtropical and temperate areas of the Old World. Chrysanthemums are especially common in East Asia, where they are often depicted in art. Cultivated species, often called mums, are grown as fall-blooming ornamentals and are important in the floral industry. Florists’ chrysanthemum (Chrysanthemum ×morifolium) has more than 100 cultivars, including button, pompon, daisy, and spider forms.

Most plants of the genus are perennial herbs or subshrubs. Many have simple aromatic leaves that alternate along the stem. Some have both disk and ray flowers in the heads, but others lack ray or disk flowers. Cultivated species and hybrids usually have large flower heads; those of wild species are much smaller.

The taxonomy of the genus is contentious and has undergone a number of revisions. Species formerly included in the genus Chrysanthemum include corn marigold (Glebionis segetum); costmary (Tanacetum balsamita); feverfew (T. parthenium); tansy (T. vulgare); Marguerite, or Paris daisy (Argyranthemum frutescens); and Shasta daisy (hybrid forms of Leucanthemum maximum).

Jai Ganesh · 2020-05-17 00:47:08

554) Binocular

Binocular, optical instrument, usually handheld, for providing a magnified stereoscopic view of distant objects, consisting of two similar telescopes, one for each eye, mounted on a single frame. A single thumbwheel may control the focus of both telescopes simultaneously, and provision may be made for adjusting the focus of each separately to allow for varying characteristics in the two eyes. Binoculars are designed to give an upright view that is correctly oriented left-to-right. Because they allow use of both eyes in a natural way, they are more comfortable than single telescopes, provide depth perception, and improve visual acuity by giving the human visual system two sets of data to process and combine.

In most binoculars, each telescope is provided with two reflecting prisms. The prisms reinvert, or erect, the inverted image supplied by the objective of each telescope. They prescribe a folded path for the light rays, allowing a shorter overall length for the instrument. When the prisms used are of the Porro type, they also provide better depth perception at greater distances by allowing the two objectives to be set farther apart than the eyepieces.

A binocular’s primary optical characteristics are commonly described by two numbers, the first of which is followed by a multiplication sign—for instance, 7×50. The first number indicates the magnification (e.g., 7×, meaning “7 times”) and the second the diameter of the objective in millimetres (1 inch is about 25 millimetres). This latter figure is a measure of the light-gathering power of the instrument. For a given magnification, larger objectives produce a brighter image in dim light but also create a more massive binocular. Handheld binoculars designed for typical uses such as hunting, sports watching, nature study, or amateur astronomy range from about 6×30 to 10×50. Instruments having greater magnifications and light-gathering power are too heavy to hold steady, especially for long periods, but they can be fixed to a tripod or other mount.

In applications in which depth perception is not important, a single telescope, called a monocular, may be employed. It is essentially one-half of a binocular and usually incorporates prisms in the light path.

Opera glasses and field glasses are binoculars with simple, often inexpensive lens systems and narrow fields of view and are usually made with magnifications of 2.5× to 5×. The lenses used in most binoculars are coated on some or all of their air-to-glass surfaces to reduce reflections.

Jai Ganesh · 2020-05-18 01:05:59

555) Chronic obstructive pulmonary disease

Overview

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory lung disease that causes obstructed airflow from the lungs. Symptoms include breathing difficulty, cough, mucus (sputum) production and wheezing. It's caused by long-term exposure to irritating gases or particulate matter, most often from cigarette smoke. People with COPD are at increased risk of developing heart disease, lung cancer and a variety of other conditions.

Emphysema and chronic bronchitis are the two most common conditions that contribute to COPD. Chronic bronchitis is inflammation of the lining of the bronchial tubes, which carry air to and from the air sacs (alveoli) of the lungs. It's characterized by daily cough and mucus (sputum) production.

Emphysema is a condition in which the alveoli at the end of the smallest air passages (bronchioles) of the lungs are destroyed as a result of damaging exposure to cigarette smoke and other irritating gases and particulate matter.

COPD is treatable. With proper management, most people with COPD can achieve good symptom control and quality of life, as well as reduced risk of other associated conditions.

Symptoms

COPD symptoms often don't appear until significant lung damage has occurred, and they usually worsen over time, particularly if smoking exposure continues. For chronic bronchitis, the main symptom is a daily cough and mucus (sputum) production at least three months a year for two consecutive years.

Other signs and symptoms of COPD may include:
• Shortness of breath, especially during physical activities
• Wheezing
• Chest tightness
• Having to clear your throat first thing in the morning, due to excess mucus in your lungs
• A chronic cough that may produce mucus (sputum) that may be clear, white, yellow or greenish
• Blueness of the lips or fingernail beds (cyanosis)
• Frequent respiratory infections
• Lack of energy
• Unintended weight loss (in later stages)
• Swelling in ankles, feet or legs

People with COPD are also likely to experience episodes called exacerbations, during which their symptoms become worse than usual day-to-day variation and persist for at least several days.

Causes

The main cause of COPD in developed countries is tobacco smoking. In the developing world, COPD often occurs in people exposed to fumes from burning fuel for cooking and heating in poorly ventilated homes.

Only about 20 to 30 percent of chronic smokers may develop clinically apparent COPD, although many smokers with long smoking histories may develop reduced lung function. Some smokers develop less common lung conditions. They may be misdiagnosed as having COPD until a more thorough evaluation is performed.

How your lungs are affected
Air travels down your windpipe (trachea) and into your lungs through two large tubes (bronchi). Inside your lungs, these tubes divide many times — like the branches of a tree — into many smaller tubes (bronchioles) that end in clusters of tiny air sacs (alveoli).

The air sacs have very thin walls full of tiny blood vessels (capillaries). The oxygen in the air you inhale passes into these blood vessels and enters your bloodstream. At the same time, carbon dioxide — a gas that is a waste product of metabolism — is exhaled.

Your lungs rely on the natural elasticity of the bronchial tubes and air sacs to force air out of your body. COPD causes them to lose their elasticity and overexpand, which leaves some air trapped in your lungs when you exhale.

Causes of airway obstruction

Causes of airway obstruction include:
• Emphysema. This lung disease causes destruction of the fragile walls and elastic fibers of the alveoli. Small airways collapse when you exhale, impairing airflow out of your lungs.
• Chronic bronchitis. In this condition, your bronchial tubes become inflamed and narrowed and your lungs produce more mucus, which can further block the narrowed tubes. You develop a chronic cough trying to clear your airways.

Cigarette smoke and other irritants

In the vast majority of cases, the lung damage that leads to COPD is caused by long-term cigarette smoking. But there are likely other factors at play in the development of COPD, such as a genetic susceptibility to the disease, because only about 20 to 30 percent of smokers may develop COPD.

Other irritants can cause COPD, including cigar smoke, secondhand smoke, pipe smoke, air pollution and workplace exposure to dust, smoke or fumes.

Alpha-1-antitrypsin deficiency

In about 1 percent of people with COPD, the disease results from a genetic disorder that causes low levels of a protein called alpha-1-antitrypsin. Alpha-1-antitrypsin (AAt) is made in the liver and secreted into the bloodstream to help protect the lungs. Alpha-1-antitrypsin deficiency can affect the liver as well as the lungs. Damage to the lung can occur in infants and children, not only adults with long smoking histories.

For adults with COPD related to AAt deficiency, treatment options include those used for people with more-common types of COPD. In addition, some people can be treated by replacing the missing AAt protein, which may prevent further damage to the lungs.

Risk factors

Risk factors for COPD include:
• Exposure to tobacco smoke. The most significant risk factor for COPD is long-term cigarette smoking. The more years you smoke and the more packs you smoke, the greater your risk. Pipe smokers, cigar smokers and marijuana smokers also may be at risk, as well as people exposed to large amounts of secondhand smoke.
• People with asthma who smoke. The combination of asthma, a chronic inflammatory airway disease, and smoking increases the risk of COPD even more.
• Occupational exposure to dusts and chemicals. Long-term exposure to chemical fumes, vapors and dusts in the workplace can irritate and inflame your lungs.
• Exposure to fumes from burning fuel. In the developing world, people exposed to fumes from burning fuel for cooking and heating in poorly ventilated homes are at higher risk of developing COPD.
• Age. COPD develops slowly over years, so most people are at least 40 years old when symptoms begin.
• Genetics. The uncommon genetic disorder alpha-1-antitrypsin deficiency is the cause of some cases of COPD. Other genetic factors likely make certain smokers more susceptible to the disease.

Complications

COPD can cause many complications, including:
• Respiratory infections. People with COPD are more likely to catch colds, the flu and pneumonia. Any respiratory infection can make it much more difficult to breathe and could cause further damage to lung tissue. An annual flu vaccination and regular vaccination against pneumococcal pneumonia can prevent some infections.
• Heart problems. For reasons that aren't fully understood, COPD can increase your risk of heart disease, including heart attack. Quitting smoking may reduce this risk.
• Lung cancer. People with COPD have a higher risk of developing lung cancer. Quitting smoking may reduce this risk.
• High blood pressure in lung arteries. COPD may cause high blood pressure in the arteries that bring blood to your lungs (pulmonary hypertension).
• Depression. Difficulty breathing can keep you from doing activities that you enjoy. And dealing with serious illness can contribute to development of depression. Talk to your doctor if you feel sad or helpless or think that you may be experiencing depression.

Prevention

Unlike some diseases, COPD has a clear cause and a clear path of prevention. The majority of cases are directly related to cigarette smoking, and the best way to prevent COPD is to never smoke — or to stop smoking now.

If you're a longtime smoker, these simple statements may not seem so simple, especially if you've tried quitting — once, twice or many times before. But keep trying to quit. It's critical to find a tobacco cessation program that can help you quit for good. It's your best chance for preventing damage to your lungs.

Occupational exposure to chemical fumes and dust is another risk factor for COPD. If you work with this type of lung irritant, talk to your supervisor about the best ways to protect yourself, such as using respiratory protective equipment.

Diagnosis

COPD is commonly misdiagnosed — former smokers may sometimes be told they have COPD, when in reality they may have simple deconditioning or another less common lung condition. Likewise, many people who have COPD may not be diagnosed until the disease is advanced and interventions are less effective.

To diagnose your condition, your doctor will review your signs and symptoms, discuss your family and medical history, and discuss any exposure you've had to lung irritants — especially cigarette smoke. Your doctor may order several tests to diagnose your condition.

Tests may include:
• Lung (pulmonary) function tests. Pulmonary function tests measure the amount of air you can inhale and exhale, and if your lungs are delivering enough oxygen to your blood.

Spirometry is the most common lung function test. During this test, you'll be asked to blow into a large tube connected to a small machine called a spirometer. This machine measures how much air your lungs can hold and how fast you can blow the air out of your lungs.

Spirometry can detect COPD even before you have symptoms of the disease. It can also be used to track the progression of disease and to monitor how well treatment is working. Spirometry often includes measurement of the effect of bronchodilator administration. Other lung function tests include measurement of lung volumes, diffusing capacity and pulse oximetry.
• Chest X-ray. A chest X-ray can show emphysema, one of the main causes of COPD. An X-ray can also rule out other lung problems or heart failure.
• CT scan. A CT scan of your lungs can help detect emphysema and help determine if you might benefit from surgery for COPD. CT scans can also be used to screen for lung cancer.
• Arterial blood gas analysis. This blood test measures how well your lungs are bringing oxygen into your blood and removing carbon dioxide.
• Laboratory tests. Laboratory tests aren't used to diagnose COPD, but they may be used to determine the cause of your symptoms or rule out other conditions. For example, laboratory tests may be used to determine if you have the genetic disorder alpha-1-antitrypsin (AAt) deficiency, which may be the cause of some cases of COPD. This test may be done if you have a family history of COPD and develop COPD at a young age, such as under age 45.

Treatment

A diagnosis of COPD is not the end of the world. Most people have mild forms of the disease for which little therapy is needed other than smoking cessation. Even for more advanced stages of disease, effective therapy is available that can control symptoms, reduce your risk of complications and exacerbations, and improve your ability to lead an active life.

Smoking cessation

The most essential step in any treatment plan for COPD is to stop all smoking. It's the only way to keep COPD from getting worse — which can eventually reduce your ability to breathe. But quitting smoking isn't easy. And this task may seem particularly daunting if you've tried to quit and have been unsuccessful.

Talk to your doctor about nicotine replacement products and medications that might help, as well as how to handle relapses. Your doctor may also recommend a support group for people who want to quit smoking. It's also a good idea to avoid secondhand smoke exposure whenever possible.

Medications

Doctors use several kinds of medications to treat the symptoms and complications of COPD. You may take some medications on a regular basis and others as needed.

Bronchodilators

These medications — which usually come in an inhaler — relax the muscles around your airways. This can help relieve coughing and shortness of breath and make breathing easier. Depending on the severity of your disease, you may need a short-acting bronchodilator before activities, a long-acting bronchodilator that you use every day or both.

Short-acting bronchodilators include albuterol (ProAir HFA, Ventolin HFA, others), levalbuterol (Xopenex HFA), and ipratropium (Atrovent). The long-acting bronchodilators include tiotropium (Spiriva), salmeterol (Serevent), formoterol (Foradil, Perforomist), arformoterol (Brovana), indacaterol (Arcapta) and aclidinium (Tudorza).

Inhaled steroids

Inhaled corticosteroid medications can reduce airway inflammation and help prevent exacerbations. Side effects may include bruising, oral infections and hoarseness.
These medications are useful for people with frequent exacerbations of COPD. Fluticasone (Flovent HFA, Flonase, others) and budesonide (Pulmicort Flexhaler, Uceris, others) are examples of inhaled steroids.

Combination inhalers

Some medications combine bronchodilators and inhaled steroids. Salmeterol and fluticasone (Advair) and formoterol and budesonide (Symbicort) are examples of combination inhalers.

Oral steroids

For people who have a moderate or severe acute exacerbation, short courses (for example, five days) of oral corticosteroids prevent further worsening of COPD. However, long-term use of these medications can have serious side effects, such as weight gain, diabetes, osteoporosis, cataracts and an increased risk of infection.

Phosphodiesterase-4 inhibitors

A new type of medication approved for people with severe COPD and symptoms of chronic bronchitis is roflumilast (Daliresp), a phosphodiesterase-4 inhibitor. This drug decreases airway inflammation and relaxes the airways. Common side effects include diarrhea and weight loss.

Theophylline

This very inexpensive medication may help improve breathing and prevent exacerbations. Side effects may include nausea, headache, fast heartbeat and tremor. Side effects are dose related, and low doses are recommended.

Antibiotics

Respiratory infections, such as acute bronchitis, pneumonia and influenza, can aggravate COPD symptoms. Antibiotics help treat acute exacerbations, but they aren't generally recommended for prevention. However, a recent study shows that the antibiotic azithromycin prevents exacerbations, but it isn't clear whether this is due to its antibiotic effect or its anti-inflammatory properties.

Lung therapies

Doctors often use these additional therapies for people with moderate or severe COPD:
• Oxygen therapy. If there isn't enough oxygen in your blood, you may need supplemental oxygen. There are several devices to deliver oxygen to your lungs, including lightweight, portable units that you can take with you to run errands and get around town.
Some people with COPD use oxygen only during activities or while sleeping. Others use oxygen all the time. Oxygen therapy can improve quality of life and is the only COPD therapy proven to extend life. Talk to your doctor about your needs and options.
• Pulmonary rehabilitation program. These programs generally combine education, exercise training, nutrition advice and counseling. You'll work with a variety of specialists, who can tailor your rehabilitation program to meet your needs.

Pulmonary rehabilitation may shorten hospitalizations, increase your ability to participate in everyday activities and improve your quality of life. Talk to your doctor about referral to a program.

Managing exacerbations

Even with ongoing treatment, you may experience times when symptoms become worse for days or weeks. This is called an acute exacerbation, and it may lead to lung failure if you don't receive prompt treatment.

Exacerbations may be caused by a respiratory infection, air pollution or other triggers of inflammation. Whatever the cause, it's important to seek prompt medical help if you notice a sustained increase in coughing, a change in your mucus or if you have a harder time breathing.

When exacerbations occur, you may need additional medications (such as antibiotics, steroids or both), supplemental oxygen or treatment in the hospital. Once symptoms improve, your doctor will talk with you about measures to prevent future exacerbations, such as quitting smoking, taking inhaled steroids, long-acting bronchodilators or other medications, getting your annual flu vaccine, and avoiding air pollution whenever possible.

Surgery

Surgery is an option for some people with some forms of severe emphysema who aren't helped sufficiently by medications alone. Surgical options include:

• Lung volume reduction surgery. In this surgery, your surgeon removes small wedges of damaged lung tissue from the upper lungs. This creates extra space in your chest cavity so that the remaining healthier lung tissue can expand and the diaphragm can work more efficiently. In some people, this surgery can improve quality of life and prolong survival.
• Lung transplant. Lung transplantation may be an option for certain people who meet specific criteria. Transplantation can improve your ability to breathe and to be active. However, it's a major operation that has significant risks, such as organ rejection, and it's necessary to take lifelong immune-suppressing medications.
• Bullectomy. Large air spaces (bullae) form in the lungs when the walls of the air sacs are destroyed. These bullae can become very large and cause breathing problems. In a bullectomy, doctors remove bullae from the lungs to help improve air flow.

Clinical trials

Lifestyle and home remedies

If you have COPD, you can take steps to feel better and slow the damage to your lungs:
• Control your breathing. Talk to your doctor or respiratory therapist about techniques for breathing more efficiently throughout the day. Also be sure to discuss breathing positions and relaxation techniques that you can use when you're short of breath.
• Clear your airways. With COPD, mucus tends to collect in your air passages and can be difficult to clear. Controlled coughing, drinking plenty of water and using a humidifier may help.
• Exercise regularly. It may seem difficult to exercise when you have trouble breathing, but regular exercise can improve your overall strength and endurance and strengthen your respiratory muscles. Discuss with your doctor which activities are appropriate for you.
• Eat healthy foods. A healthy diet can help you maintain your strength. If you're underweight, your doctor may recommend nutritional supplements. If you're overweight, losing weight can significantly help your breathing, especially during times of exertion.
• Avoid smoke and air pollution. In addition to quitting smoking, it's important to avoid places where others smoke. Secondhand smoke may contribute to further lung damage. Other types of air pollution also can irritate your lungs.
• See your doctor regularly. Stick to your appointment schedule, even if you're feeling fine. It's important to steadily monitor your lung function. And be sure to get your annual flu vaccine in the fall to help prevent infections that can worsen your COPD. Ask your doctor when you need the pneumococcal vaccine. Let your doctor know if you have worsening symptoms or you notice signs of infection.

Coping and support

Living with COPD can be a challenge — especially as it becomes harder to catch your breath. You may have to give up some activities you previously enjoyed. Your family and friends may have difficulty adjusting to some of the changes.

It can help to share your fears and feelings with your family, friends and doctor. You may also want to consider joining a support group for people with COPD. And you may benefit from counseling or medication if you feel depressed or overwhelmed.

Preparing for your appointment

If your primary care doctor suspects that you have COPD, you'll likely be referred to a pulmonologist — a doctor who specializes in lung disorders.

What you can do:
Before your appointment, you might want to write a list of answers to the following questions:
• What symptoms are you experiencing? When did they start?
• What makes your symptoms worse? Better?
• Does anyone in your family have COPD?
• Have you had any treatment for COPD? If so, what was it and did it help?
• Have you ever taken beta blockers for your high blood pressure or heart?
• Are you being treated for any other medical conditions?
• What medications and supplements do you take regularly?

You might want to have a friend or family member accompany you to your appointment. Often, two sets of ears are better than one when you're learning about a complicated medical problem, such as COPD. Take notes if this helps.
What to expect from your doctor
Your doctor may ask some of the following questions:
• How long have you had a cough?
• Do you get short of breath easily?
• Have you noticed any wheezing when you breathe?
• Do you or have you ever smoked cigarettes?
• Would you like help in quitting?

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