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#2 Re: Ganesh's Puzzles » General Quiz » Today 00:16:41


#8770. What does the term is Biology 'Microevolution' mean?

#8771. What does the term in Biology 'Mitochondrion' mean?

#4 Re: Help Me ! » LaTeX - A Crash Course » Yesterday 22:07:27

Important Notes on Angles

0^o < \ Acute \ angle < \ {90}^o


{90}^o < \ Obtuse \ angle < {180}^o


{180}^o < \ Reflex \ angle < {360}^o


A \ right \ angle \ is \ equal \ to \ {90}^o


A \ straight \ angle \ is \ equal \ to {180}^o.



#5 Dark Discussions at Cafe Infinity » Blue Quotes - I » Yesterday 17:31:10

Replies: 0

Blue Quotes - I

1. There is no blue without yellow and without orange. Vincent Van Gogh

2. All the armies of Europe, Asia and Africa combined, with all the treasure of the earth (our own excepted) in their military chest; with a Buonaparte for a commander, could not by force, take a drink from the Ohio, or make a track on the Blue Ridge, in a trial of a thousand years. - Abraham Lincoln

3. It suddenly struck me that that tiny pea, pretty and blue, was the Earth. I put up my thumb and shut one eye, and my thumb blotted out the planet Earth. I didn't feel like a giant. I felt very, very small. - Neil Armstrong

4. When you look at the light bulb above you, you remember Thomas Alva Edison. When the telephone bell rings, you remember Alexander Graham Bell. Marie Curie was the first woman to win the Nobel Prize. When you see the blue sky, you think of Sir C.V. Raman. - A. P. J. Abdul Kalam

5. Our motto at Blue Origin is 'Gradatim Ferociter': 'Step by Step, Ferociously.' - Jeff Bezos

6. I think I have something tonight that's not quite correct for evening wear. Blue suede shoes. - Elvis Presley

7. Whenever I gaze up at the moon, I feel like I'm on a time machine. I am back to that precious pinpoint of time, standing on the foreboding - yet beautiful - Sea of Tranquility. I could see our shining blue planet Earth poised in the darkness of space. - Buzz Aldrin

8. I would wear the blue overalls of the fieldworker and often wore round, rimless glasses known as Mazzawati teaglasses. I had a car, and I wore a chauffeur's cap with my overalls. The pose of chauffeur was convenient because I could travel under the pretext of driving my master's car. - Nelson Mandela

9. I have very little fashion sense, and to tell you the truth, I give it very little thought. I dress to be as comfortable as I possibly can. Most of my clothing is either black, grey, or dark blue, and I don't really wear a lot of colours. But I do like jackets. I have a little bit of an obsession with them. - Leonardo DiCaprio

10. Only peril can bring the French together. One can't impose unity out of the blue on a country that has 265 different kinds of cheese. - Charles de Gaulle

11. Oh, 1994, April 27. There won't be a day like that ever again. I mean, the sky was blue, with a blueness that had never been there before. - Desmond Tutu

12. I don't know all the future steps, but I know one of them: we need to build a low-cost, highly operable, reusable launch vehicle. No matter which path we take, it has to include that gate, and so that's why that's Blue Origin's mission. - Jeff Bezos

13. We really have the most beautiful planet in our solar system. None other can sustain life like we know it. None other has blue water and white clouds covering colorful landmasses filled with thriving, beautiful, living things like human beings. - Sunita Williams

14. We just think that there are all these different ways that people want to share, and that compressing them all into a single blue app is not the right format of the future. - Mark Zuckerberg

15. But growing as an India cricketer it was about the blue jersey and the pride we all felt wearing that jersey. - Mithali Raj

16. At home, a T-shirt and something loose like harem pants would do. If I'm stepping out, a pair of blue jeans and a white tee are just fine. - Genelia D'Souza

17. A voyage to Europe in the summer of 1921 gave me the first opportunity of observing the wonderful blue opalescence of the Mediterranean Sea. It seemed not unlikely that the phenomenon owed its origin to the scattering of sunlight by the molecules of the water. - C. V. Raman

18. I would like to clarify that the only adoption I am involved is through the Blue Cross Animal Welfare Shelter where we provide healthy and friendly homeless animals for adoption. - Amala Akkineni

19. My body is very shaped, and I like to be simple. I don't like to use so many colors. My best colors are black, white and blue. - Monica Bellucci

20. Nutrition is the topmost priority for me with my pets at home as well as for the team at Blue Cross. - Amala Akkineni.


#6 Dark Discussions at Cafe Infinity » Blown and Blows Quotes » Yesterday 16:16:37

Replies: 0

Blown and Blows Quotes

1. The Flower that once has blown forever dies. - Omar Khayyam

2. A new breeze is blowing, and a world refreshed by freedom seems reborn; for in man's heart, if not in fact, the day of the dictator is over. The totalitarian era is passing, its old ideas blown away like leaves from an ancient, lifeless tree. - George H. W. Bush

3. I've always been more interested in organisms that can move on their own than in stationary plants. But when I canoe or hike along the edge of lakes or oceans and see trees that seem to be growing out of rock faces, I am blown away. How do they do it? - David Suzuki

4. I look around at my peers, and I'm so blown away by their talent and their beauty and their cool style, as well as their ability to be an actress and be a movie star and be good at it. I mean, they're so good, and we're all trying to get the same parts. - Anne Hathaway

5. To me the meanest flower that blows can give thoughts that do often lie too deep for tears. - William Wordsworth

6. A straw vote only shows which way the hot air blows. - O. Henry

7. Most people want to become movie stars and I just want to be in the business. I already was a star. If I get the part of a lifetime and it blows up, then that's wonderful. But if the acting doesn't work, fine. I'll just be a producer. And if the producing doesn't work, fine. I've got a lot of other stuff. - Carl Lewis.


#7 Jokes » One liners - 157 » Yesterday 15:40:42

Replies: 0

I like to hold hands at the movies... which always seems to startle strangers.
* * *
What did the paper say to the pencil? You've got a good point!
* * *
When I was young, I was afraid of the dark. Now when I get my electric bill, I am afraid of the light.
* * *
The person who invented the door knock won the No-bell prize.
* * *
Young riders pick a destination and go... Old riders pick a direction and go.
* * *

#8 Re: Ganesh's Puzzles » Doc, Doc! » Yesterday 15:21:06


#2059. What does the medical term 'Cranial nerves' mean?

#9 Re: Ganesh's Puzzles » English language puzzles » Yesterday 15:04:02


#5007. What does the noun dither mean?

#5008. What does the adjective diurnal mean?

#11 Re: This is Cool » Miscellany » Yesterday 14:12:16

1558) Dentist


What Is a Dentist?

Dentists are trained professionals who help care for the teeth and mouth. Regularly seeing a dentist can help you to maintain a good level of dental health, which may have a direct impact on your overall well-being.

What Does a Dentist Do?

A dentist has many responsibilities, and one of the most important is promoting good dental hygiene. This helps to prevent complications in your mouth or other parts of the body.

A dentist also diagnoses and treats problems of the gums, teeth, and mouth. Dentists use modern technology and equipment like X-ray machines, lasers, drills, brushes, scalpels, and other medical tools when performing dental procedures. They also wear protective equipment like gloves, masks, and safety glasses to prevent the spread of germs or bacteria.

Some common dentistry tasks include:

* Teaching people about dental hygiene
* Filling cavities
* Removing buildup or decay from teeth
* Repairing or removing damaged teeth
* Reviewing X-rays and diagnostics
* Giving anesthesia
* Putting in fillings or sealants
* Checking the growth of teeth and jawbones.

Dentistry requires a team approach, and the dentist is the leader. Working with the dentist are dental assistants, hygienists, and lab technicians. Together, the team ensures that people get quality dental care.


A dentist, also known as a dental surgeon, is a health care professional who specializes in dentistry (the diagnosis, prevention, management, and treatment of diseases and conditions of the oral cavity and other aspects of the craniofacial complex including the temporomandibular joint). The dentist's supporting team aids in providing oral health services. The dental team includes dental assistants, dental hygienists, dental technicians, and sometimes dental therapists.


Middle Ages

In China as well as France, the first people to perform dentistry were barbers. They have been categorized into 2 distinct groups: guild of barbers and lay barbers. The first group, the Guild of Barbers, was created to distinguish more educated and qualified dental surgeons from lay barbers. Guild barbers were trained to do complex surgeries. The second group, the lay barbers, were qualified to perform regular hygienic services such as shaving and tooth extraction as well as basic surgery. However, in 1400, France made decrees prohibiting lay barbers from practicing all types of surgery. In Germany as well as France from 1530 to 1575 publications completely devoted to dentistry were being published. Ambroise Paré, often known as the Father of Surgery, published his own work about the proper maintenance and treatment of teeth. Ambroise Paré was a French barber surgeon who performed dental care for multiple French monarchs. He is often credited with having raised the status of barber surgeons.

Modern dentistry

Pierre Fauchard of France is often referred to as the "father of modern dentistry" for being the first to publish a scientific textbook (1728) on the techniques and practices of dentistry. Over time, trained dentists immigrated from Europe to the Americas to practice dentistry, and by 1760, America had its own native born practicing dentists. Newspapers were used at the time to advertise and promote dental services. In America from 1768 to 1770 the first application of dentistry to verify forensic cases was being pioneered; this was called forensic dentistry. With the rise of dentists, there was also the rise of new methods to improve the quality of dentistry. These new methods included the spinning wheel to rotate a drill and chairs made specifically for dental patients.

In the 1840s the world's first dental school and national dental organization were established. Along with the first dental school came the establishment of the Doctor of Dental Surgery degree, often referred to as a DDS degree. In response to the rise in new dentists as well as dentistry techniques, the first dental practice act was established to regulate dentistry. In the United States, the First Dental Practice Act required dentists to pass each specific state medical board exam in order to practice dentistry in that particular state. However, because the dental act was rarely enforced, some dentists did not obey the act. From 1846 to 1855 new dental techniques were being invented such as the use of ester anesthesia for surgery, and the cohesive gold foil method which enabled gold to be applied to a cavity. The American Dental Association was established in 1859 after a meeting with 26 dentists. Around 1867, the first university-associated dental school was established, Harvard Dental School. Lucy Hobbs Taylor was the first woman to earn a dental degree.

In the 1880s, tube toothpaste was created which replaced the original forms of powder or liquid toothpaste. New dental boards, such as the National Association of Dental Examiners, were created to establish standards and uniformity among dentists. In 1887 the first dental laboratory was established; dental laboratories are used to create dentures and crowns that are specific to each patient. In 1895 the dental X-ray was discovered by a German physicist, Wilhelm Röntgen.

In the 20th century, new dental techniques and technology were invented such as the porcelain crowns (1903), Novocain (a local anesthetic) 1905, precision cast fillings (1907), nylon toothbrushes (1938), water fluoridation (1945), fluoride toothpaste (1950), air driven dental tools (1957), lasers (1960), electric toothbrushes (1960), and home tooth bleaching kits (1989) were invented. Inventions such as the air driven dental tools ushered in a new high-speed dentistry.


By nature of their general training, a licensed dentist can carry out most dental treatments such as restorative (dental restorations, crowns, bridges), orthodontics (braces), prosthodontic (dentures, crown/bridge), endodontic (root canal) therapy, periodontal (gum) therapy, and oral surgery (extraction of teeth), as well as performing examinations, taking radiographs (x-rays) and diagnosis. Additionally, dentists can further engage in oral surgery procedures such as dental implant placement. Dentists can also prescribe medications such as antibiotics, fluorides, pain killers, local anesthetics, sedatives/hypnotics and any other medications that serve in the treatment of the various conditions that arise in the head and neck.

All DDS and DMD degree holders are legally qualified to perform a number of more complex procedures such as gingival grafts, bone grafting, sinus lifts, and implants, as well as a range of more invasive oral and maxillofacial surgery procedures, though many choose to pursue residencies or other post-doctoral education to augment their abilities. A few select procedures, such as the administration of General anesthesia, legally require postdoctoral training in the US. While many oral diseases are unique and self-limiting, poor conditions in the oral cavity can lead to poor general health and vice versa; notably, there is a significant link between periodontal and cardiovascular disease. Conditions in the oral cavity may also be indicative of other systemic diseases such as osteoporosis, diabetes, AIDS, and various blood diseases, including malignancies and lymphoma.

Several studies have suggested that dentists and dental students are at high risk of burnout. During burnout, dentists experience exhaustion, alienate from work and perform less efficiently. A systemic study identified risk factors associated with this condition such as practitioner's young age, personality type, gender, the status of education, high job strain and/or working hours, and the burden of clinical degrees requisites. The authors of this study concluded that intervention programs at an early stage during the undergraduate level may provide practitioners with a good strategy to prepare for / cope with this condition.


Depending on the country, all dentists are required to register with their national or local health board, regulators, and professional indemnity insurance, in order to practice dentistry. In the UK, dentists are required to register with the General Dental Council. In Australia, it is the Dental Board of Australia, while in the United States, dentists are registered according to the individual state board. The main role of a dental regulator is to protect the public by ensuring only qualified dental practitioners are registered, handle any complaints or misconduct, and develop national guidelines and standards for dental practitioners to follow.

Specialty (dentistry)

For many countries, after satisfactory completion of post-graduate training, dental specialists are required to join a specialist board or list, in order to use the title 'specialist'.


#12 Re: This is Cool » Important Laws/Principles in Physics » Yesterday 03:12:58

35) Fermi–Dirac statistics

Fermi–Dirac statistics (F–D statistics) is a type of quantum statistics that applies to the physics of a system consisting of many non-interacting, identical particles that obey the Pauli exclusion principle. A result is the Fermi–Dirac distribution of particles over energy states. It is named after Enrico Fermi and Paul Dirac, each of whom derived the distribution independently in 1926 (although Fermi derived it before Dirac). Fermi–Dirac statistics is a part of the field of statistical mechanics and uses the principles of quantum mechanics.

F–D statistics applies to identical and indistinguishable particles with half-integer spin (1/2, 3/2, etc.), called fermions, in thermodynamic equilibrium. For the case of negligible interaction between particles, the system can be described in terms of single-particle energy states. A result is the F–D distribution of particles over these states where no two particles can occupy the same state, which has a considerable effect on the properties of the system. F–D statistics is most commonly applied to electrons, a type of fermion with spin 1/2.

A counterpart to F–D statistics is Bose–Einstein statistics (B–E statistics), which applies to identical and indistinguishable particles with integer spin (0, 1, 2, etc.) called bosons. In classical physics, Maxwell–Boltzmann statistics (M–B statistics) is used to describe particles that are identical and treated as distinguishable. For both B–E and M–B statistics, more than one particle can occupy the same state, unlike F–D statistics.

#13 Re: Science HQ » Natural Satellite » Yesterday 00:42:11

15) Umbriel

Umbriel is a moon of Uranus discovered on October 24, 1851, by William Lassell. It was discovered at the same time as Ariel and named after a character in Alexander Pope's poem The math of the Lock. Umbriel consists mainly of ice with a substantial fraction of rock, and may be differentiated into a rocky core and an icy mantle. The surface is the darkest among Uranian moons, and appears to have been shaped primarily by impacts. However, the presence of canyons suggests early endogenic processes, and the moon may have undergone an early endogenically driven resurfacing event that obliterated its older surface.

Covered by numerous impact craters reaching 210 km (130 mi) in diameter, Umbriel is the second most heavily cratered satellite of Uranus after Oberon. The most prominent surface feature is a ring of bright material on the floor of Wunda crater. This moon, like all moons of Uranus, probably formed from an accretion disk that surrounded the planet just after its formation. The Uranian system has been studied up close only once, by the spacecraft Voyager 2 in January 1986. It took several images of Umbriel, which allowed mapping of about 40% of the moon's surface.

Discovery and name

Umbriel, along with another Uranian satellite, Ariel, was discovered by William Lassell on October 24, 1851. Although William Herschel, the discoverer of Titania and Oberon, claimed at the end of the 18th century that he had observed four additional moons of Uranus, his observations were not confirmed and those four objects are now thought to be spurious.

All of Uranus's moons are named after characters created by William Shakespeare or Alexander Pope. The names of all four satellites of Uranus then known were suggested by John Herschel in 1852 at the request of Lassell. Umbriel is the "dusky melancholy sprite" in Alexander Pope's The math of the Lock, and the name suggests the Latin umbra, meaning shadow. The moon is also designated Uranus II.


Umbriel orbits Uranus at the distance of about 266,000 km (165,000 mi), being the third farthest from the planet among its five major moons. Umbriel's orbit has a small eccentricity and is inclined very little relative to the equator of Uranus. Its orbital period is around 4.1 Earth days, coincident with its rotational period. In other words, Umbriel is a synchronous or tidally locked satellite, with one face always pointing toward its parent planet.[6] Umbriel's orbit lies completely inside the Uranian magnetosphere. This is important, because the trailing hemispheres of airless satellites orbiting inside a magnetosphere (like Umbriel) are struck by magnetospheric plasma, which co-rotates with the planet. This bombardment may lead to the darkening of the trailing hemispheres, which is actually observed for all Uranian moons except Oberon  Umbriel also serves as a sink of the magnetospheric charged particles, which creates a pronounced dip in energetic particle count near the moon's orbit as observed by Voyager 2 in 1986.

Because Uranus orbits the Sun almost on its side, and its moons orbit in the planet's equatorial plane, they (including Umbriel) are subject to an extreme seasonal cycle. Both northern and southern poles spend 42 years in complete darkness, and another 42 years in continuous sunlight, with the Sun rising close to the zenith over one of the poles at each solstice. The Voyager 2 flyby coincided with the southern hemisphere's 1986 summer solstice, when nearly the entire northern hemisphere was unilluminated. Once every 42 years, when Uranus has an equinox and its equatorial plane intersects the Earth, mutual occultations of Uranus's moons become possible. In 2007–2008 a number of such events were observed including two occultations of Titania by Umbriel on August 15 and December 8, 2007 as well as of Ariel by Umbriel on August 19, 2007.

Currently Umbriel is not involved in any orbital resonance with other Uranian satellites. Early in its history, however, it may have been in a 1:3 resonance with Miranda. This would have increased Miranda's orbital eccentricity, contributing to the internal heating and geological activity of that moon, while Umbriel's orbit would have been less affected. Due to Uranus's lower oblateness and smaller size relative to its satellites, its moons can escape more easily from a mean motion resonance than those of Jupiter or Saturn. After Miranda escaped from this resonance (through a mechanism that probably resulted in its anomalously high orbital inclination), its eccentricity would have been damped, turning off the heat source.

Composition and internal structure

Umbriel is the third-largest and fourth-most massive of the Uranian moons. Although Umbriel is the 13th-largest moon in the solar system, it is only the 14th-most massive. The moon's density is 1.39 g/cm^3, which indicates that it mainly consists of water ice, with a dense non-ice component constituting around 40% of its mass. The latter could be made of rock and carbonaceous material including heavy organic compounds known as tholins. The presence of water ice is supported by infrared spectroscopic observations, which have revealed crystalline water ice on the surface of the moon. Water ice absorption bands are stronger on Umbriel's leading hemisphere than on the trailing hemisphere. The cause of this asymmetry is not known, but it may be related to the bombardment by charged particles from the magnetosphere of Uranus, which is stronger on the trailing hemisphere (due to the plasma's co-rotation). The energetic particles tend to sputter water ice, decompose methane trapped in ice as clathrate hydrate and darken other organics, leaving a dark, carbon-rich residue behind.

Except for water, the only other compound identified on the surface of Umbriel by the infrared spectroscopy is carbon dioxide, which is concentrated mainly on the trailing hemisphere. The origin of the carbon dioxide is not completely clear. It might be produced locally from carbonates or organic materials under the influence of the energetic charged particles coming from the magnetosphere of Uranus or the solar ultraviolet radiation. This hypothesis would explain the asymmetry in its distribution, as the trailing hemisphere is subject to a more intense magnetospheric influence than the leading hemisphere. Another possible source is the outgassing of the primordial CO2 trapped by water ice in Umbriel's interior. The escape of CO2 from the interior may be a result of past geological activity on this moon.

Umbriel may be differentiated into a rocky core surrounded by an icy mantle. If this is the case, the radius of the core (317 km) is about 54% of the radius of the moon, and its mass is around 40% of the moon's mass—the parameters are dictated by the moon's composition. The pressure in the center of Umbriel is about 0.24 GPa (2.4 kbar).The current state of the icy mantle is unclear, although the existence of a subsurface ocean is considered unlikely.

Surface features

Umbriel's surface is the darkest of the Uranian moons, and reflects less than half as much light as Ariel, a sister satellite of similar size. Umbriel has a very low Bond albedo of only about 10% as compared to 23% for Ariel. The reflectivity of the moon's surface decreases from 26% at a phase angle of 0° (geometric albedo) to 19% at an angle of about 1°. This phenomenon is called opposition surge. The surface of Umbriel is slightly blue in color, while fresh bright impact deposits (in Wunda crater, for instance) are even bluer. There may be an asymmetry between the leading and trailing hemispheres; the former appears to be redder than the latter. The reddening of the surfaces probably results from space weathering from bombardment by charged particles and micrometeorites over the age of the Solar System. However, the color asymmetry of Umbriel is likely caused by accretion of a reddish material coming from outer parts of the Uranian system, possibly, from irregular satellites, which would occur predominately on the leading hemisphere. The surface of Umbriel is relatively homogeneous—it does not demonstrate strong variation in either albedo or color.

Mean radius  :  584.7±2.8 km (0.092 Earths).

#16 Re: Ganesh's Puzzles » General Quiz » Yesterday 00:06:21


#8768. What does the term 'Grammatology' mean?

#8769. What does the term 'Graphology' mean?

#17 Re: Dark Discussions at Cafe Infinity » crème de la crème » Yesterday 00:04:02

1186) Ingrid Bergman


Ingrid Bergman (29 August 1915 – 29 August 1982) was a Swedish actress who starred in a variety of European and American films, television movies, and plays. With a career spanning five decades, she is often regarded as one of the most influential screen figures in cinematic history.

According to the St. James Encyclopedia of Popular Culture, upon her arrival in the U.S. Bergman quickly became "the ideal of American womanhood" and a contender for Hollywood's greatest leading actress. David O. Selznick once called her "the most completely conscientious actress" he had ever worked with. In 1999, the American Film Institute recognised Bergman as the fourth greatest female screen legend of Classic Hollywood Cinema.

She won numerous accolades, including three Academy Awards, two Primetime Emmy Awards, a Tony Award, four Golden Globe Awards, BAFTA Award and a Volpi Cup. She is one of only four actresses to have received at least three acting Academy Awards (only Katharine Hepburn has four).

Born in Stockholm to a Swedish father and a German mother, Bergman began her acting career in Swedish and German films. Her introduction to the U.S. audience came in the English-language remake of Intermezzo (1939). Known for her naturally luminous beauty, she starred in Casablanca (1942) as Ilsa Lund, her most famous role, opposite Humphrey Bogart. Bergman's notable performances in the 1940s include the dramas For Whom the Bell Tolls (1943), Gaslight (1944), The Bells of St. Mary's (1945), and Joan of Arc (1948), all of which earned her nominations for the Academy Award for Best Actress; she won for Gaslight. She made three films with Alfred Hitchcock: Spellbound (1945), with Gregory Peck, Notorious (1946), opposite Cary Grant and Under Capricorn (1949), alongside Joseph Cotten.

In 1950, she starred in Roberto Rossellini's Stromboli, released after the revelation she was having an affair with Rossellini; that and her pregnancy prior to their marriage created a scandal in the U.S. that prompted her to remain in Europe for several years. During this time she starred in Rossellini's Europa '51 and Journey to Italy (1954), now critically acclaimed, the former of which won her the Volpi Cup for Best Actress. She had a successful return to working for a Hollywood studio in Anastasia (1956), winning her second Academy Award for Best Actress. Soon after, she co-starred with Grant in the romance Indiscreet (1958). In 1969, she starred in the acclaimed and highly successful film Cactus Flower. In later years, Bergman won her third Academy Award, this one for Best Supporting Actress, for her role in Murder on the Orient Express (1974). In 1978, she starred in Ingmar Bergman's (no relation) Swedish Autumn Sonata receiving her sixth Best Actress nomination. Bergman spoke five languages – Swedish, English, German, Italian and French – and acted in each.

In her final role, she portrayed the late Israeli Prime Minister Golda Meir in the television miniseries A Woman Called Golda (1982) for which she posthumously won her second Emmy Award for Best Actress. In 1974, Bergman discovered she was suffering from breast cancer but continued to work until shortly before her death on her sixty-seventh birthday.


Ingrid Bergman, (born August 29, 1915, Stockholm, Sweden—died August 29, 1982, London, England), was a Swedish actress whose natural charm, freshness, intelligence, and vitality made her the image of sincerity and idealized womanhood. One of cinema’s biggest stars, she appeared in such classics as Casablanca (1942) and Notorious (1946).

Early life

Bergman was only two years old when her mother died, and about a decade later her father also passed away. Although she was shy, she long dreamed of becoming an actress, and she worked assiduously for admission to the Royal Dramatic Theatre School in Stockholm, where she studied for a year. Her first credited film appearance was in Munkbrogreven (1935; The Count of the Old Monk’s Bridge), and it was followed by challenging roles in such Swedish films as the original Intermezzo (1936) and En kvinnas ansikte (1938; A Woman’s Face). In 1939 she starred in the Hollywood version of Intermezzo, which was a box-office hit.

Stardom: Casablanca, Gaslight, and Notorious

Several films later Bergman became a star with Casablanca (1942), one of cinema’s most iconic films. In this romantic drama, Bergman played Ilsa Lund, a woman torn between two men (played by Humphrey Bogart and Paul Henreid) during World War II. Now highly sought after, Bergman appeared in a series of critical and commercial successes that included For Whom the Bell Tolls (1943), which was based on Ernest Hemingway’s novel, and the film noir Gaslight (1944). In the latter movie she starred as a woman whose husband (Charles Boyer) attempts to drive her mad, and her performance earned her an Academy Award for best actress.

Bergman received another Oscar nod for her portrayal of a nun in The Bells of St. Mary’s (1945). During this time she also earned acclaim for two thrillers directed by Alfred Hitchcock: Spellbound (1945), in which she played a psychiatrist attempting to help an amnesiac patient (Gregory Peck), and Notorious (1946), an espionage drama that costarred Cary Grant. Bergman continued to show her impressive range by playing the titular character in Joan of Arc (1948), for which she received her fourth Academy Award nomination.

Scandal and later films

During the filming of Stromboli (1950), Bergman began a love affair with the Italian director Roberto Rossellini, and they had a son before she obtained a divorce from her first husband. A scandal ensued—a U.S. senator notably called her “a horrible example of womanhood and a powerful influence for evil”—and Bergman was banned in Hollywood. She returned to Europe, where she appeared in Italian and French films such as Europa ’51 (1952; The Greatest Love) and Viaggio in Italia (1954; Journey to Italy). During this time she married (1950–57) Rossellini, and the couple had two more children, including Isabella Rossellini, who became a noted model and actress.

Bergman made a triumphant Hollywood comeback in Anastasia (1956), for which she won her second Academy Award. She continued to appear in Hollywood productions, including The Inn of the Sixth Happiness (1958), as well as in European films. She won her third Oscar, for best supporting actress, for her role in the highly successful film Murder on the Orient Express (1974). However, most agree that her greatest performance in her later years was as a concert pianist in the Swedish film Höstsonaten (1978; Autumn Sonata), directed by Ingmar Bergman; she received her seventh and final Academy Award nomination for the drama. Her last role was that of Golda Meir, the Israeli prime minister, in the television play A Woman Called Golda (1981). For this role she was posthumously awarded an Emmy Award in 1982.

In addition to her film work, Bergman also acted on the stage. In 1940 she made her Broadway debut in Liliom. She later appeared in such critically acclaimed plays as Hedda Gabler (Paris, 1962), A Month in the Country (Great Britain, 1965), and Captain Brassbound’s Conversion (London, 1971). She won a Tony Award for her performance in Joan of Lorraine (1946–47), and her last Broadway appearance was in The Constant Wife (1975). She also starred in the television plays The Turn of the Screw (1959) and Hedda Gabler (1963).

My Story (1980) is her autobiography with alternating sections by Alan Burgess.


#18 Re: Help Me ! » LaTeX - A Crash Course » 2022-12-02 19:41:00


A circle is a curved plane figure. Every point on the circle is equidistant from a fixed point known as the center of the circle. It is a 2D shape and is measured in terms of radius. The word ‘Circle’ is derived from the Latin word 'circulus' meaning small ring.

What is Circle?

A circle is a two-dimensional figure formed by a set of points that are at a constant or at a fixed distance (radius) from a fixed point (center) on the plane. The fixed point is called the origin or center of the circle and the fixed distance of the points from the origin is called the radius.

Parts of a Circle

There are many parts or components of a circle that we should know to understand its properties. A circle has mainly the following parts:

* Circumference: It is also referred to as the perimeter of a circle and can be defined as the distance around the boundary of the circle.

* Radius of Circle: Radius is the distance from the center of a circle to any point on its boundary. A circle has many radii as it is the distance from the center and touches the boundary of the circle at various points.

* Diameter: A diameter is a straight line passing through the center that connects two points on the boundary of the circle. We should note that there can be multiple diameters in the circle, but they should:

** pass through the center.
** be straight lines.
** touch the boundary of the circle at two distinct points which lie opposite to each other.

* Chord of a Circle: A chord is any line segment touching the circle at two different points on its boundary. The longest chord in a circle is its diameter which passes through the center and divides it into two equal parts.

* Tangent: A tangent is a line that touches the circle at a unique point and lies outside the circle.

* Secant: A line that intersects two points on an arc/circumference of a circle is called the secant.

* Arc of a Circle: An arc of a circle is referred to as a curve, that is a part or portion of its circumference.

* Segment in a Circle: The area enclosed by the chord and the corresponding arc in a circle is called a segment. There are two types of segments - minor segment, and major segment.

* Sector of a Cirlce: The sector of a circle is defined as the area enclosed by two radii and the corresponding arc in a circle. There are two types of sectors - minor sector, and major sector.

Properties of Circle

Here is a list of properties of a circle:

* A circle is a closed 2D shape that is not a polygon. It has one curved face.
* Two circles can be called congruent if they have the same radius.
* Equal chords are always equidistant from the center of the circle.
* The perpendicular bisector of a chord passes through the center of the circle.
* When two circles intersect, the line connecting the intersecting points will be perpendicular to the line connecting their center points.
* Tangents drawn at the endpoints of the diameter are parallel to each other.

Let's see the list of important formulae pertaining to any circle.

Area of a Circle Formula: The area of a circle refers to the amount of space covered by the circle. It totally depends on the length of its radius :

Area = \pi{r^2} square units

gives .


Circumference of a Circle Formula: The circumference is the total length of the boundary of a circle.

Circumference = 2\pi{r} units


Arc Length Formula: An arc is a section (part) of the circumference.

Length \ of \ an \ arc = \theta \times r. \ Here, \theta \ is \ in \radians.


Area of a Sector Formula: If a sector makes an angle θ (measured in radians) at the center, then the area of the sector of a circle =

(\theta \times r^2) \div 2. \ Here, \theta \ is \ in \ radians.


Length of Chord Formula: It can be calculated if the angle made by the chord at the center and the value of radius is known.

Length \ of \ chord = 2 r sin\dfrac{\theta}{2}. \ Here, \ \theta \ is \ in \ radians.


Area of Segment Formula: The segment of a circle is the region formed by the chord and the corresponding arc covered by the segment.

The \ area \ of \ a \ segment = r^2(\theta − sin\theta) \div 2. Here, \theta \ is \ in \ radians.


#19 Dark Discussions at Cafe Infinity » Blow and Blowing Quotes » 2022-12-02 16:32:16

Replies: 0

Blow and Blowing Quotes

1. An optimist may see a light where there is none, but why must the pessimist always run to blow it out? - Rene Descartes

2. The earth is supported by the power of truth; it is the power of truth that makes the sun shine and the winds blow; indeed all things rest upon truth. - Chanakya

3. To finish a work? To finish a picture? What nonsense! To finish it means to be through with it, to kill it, to rid it of its soul, to give it its final blow the coup de grace for the painter as well as for the picture. - Pablo Picasso

4. Beware of the man who does not return your blow: he neither forgives you nor allows you to forgive yourself. - George Bernard Shaw

5. Never will the doctrine of spontaneous generation recover from the mortal blow struck by this simple experiment. - Louis Pasteur

6. My friends, whoever has had experience of evils knows how whenever a flood of ills comes upon mortals, a man fears everything; but whenever a divine force cheers on our voyage, then we believe that the same fate will always blow fair. - Aeschylus

7. I haven't been as wild with my money as somebody like me might have been. I've been very safe, very conservative with investments. I don't blow money. I don't have a ton of houses. I know things can go away. I've already had that experience. - Jim Carrey

8. We all have insecurities, and the thing that makes them crippling is that we all have the ability to blow them up into such huge issues in our minds, that we might as well have a facial deformity. It keeps us from really going out there and living our lives, and forgetting about hating yourself and just experiencing the world around you. - Christina Ricci

9. I think when you love a child, it's a different kind of love. You think, 'I love more every day. I love more every day, more every day, I couldn't possibly love any more, I'm going to blow up.' And then you blow up. Your chest actually starts to hurt. You love so much, you think I can't love any more. - Sharon Stone

10. I take rejection as someone blowing a bugle in my ear to wake me up and get going, rather than retreat. - Sylvester Stallone

11. Nirvana is not the blowing out of the candle. It is the extinguishing of the flame because day is come. - Rabindranath Tagore

12. I pass my life in preventing the storm from blowing down the tent, and I drive in the pegs as fast as they are pulled up. - Abraham Lincoln

13. A new breeze is blowing, and a world refreshed by freedom seems reborn; for in man's heart, if not in fact, the day of the dictator is over. The totalitarian era is passing, its old ideas blown away like leaves from an ancient, lifeless tree. - George H. W. Bush

14. Terrorists are not following Islam. Killing people and blowing up people and dropping bombs in places and all this is not the way to spread the word of Islam. So people realize now that all Muslims are not terrorists. - Muhammad Ali

15. Asceticism doesn't lie in ascetic robes or in walking staff nor in the ashes. Asceticism doesn't lie in the earring nor in the shaven head nor blowing a conch. Asceticism lies in remaining pure amidst impurities. - Guru Nanak

16. I was punished for blowing the whistle on my father's lifestyle. - Tatum O'Neal.


#20 Re: Ganesh's Puzzles » Doc, Doc! » 2022-12-02 15:38:06


#2058. What does the medical term 'Stress fracture' mean?

#21 Re: Ganesh's Puzzles » English language puzzles » 2022-12-02 15:08:50


#5005. What does the verb (used with object) constrain mean?

#5006. What does the noun consul mean?

#23 Jokes » One liners - 156 » 2022-12-02 14:26:13

Replies: 0

Treat each day as your last, one day you will be right.
* * *
Do skunks celebrate Valentine's Day? Sure, they're very scent-imental!
* * *
You are not even beneath my contempt.
* * *
The most dangerous room in the house really depends on where your wife is at the moment.
* * *
Yesterday I decided to change my WiFi name to "Hack me if you can" and when I woke up this morning I saw the name changed to "Challenge accepted" somebody help.
* * *

#24 Re: This is Cool » Miscellany » 2022-12-02 14:13:19

1557) Bone


A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, and enable mobility. Bones come in a variety of shapes and sizes and have complex internal and external structures.[2] They are lightweight yet strong and hard and serve multiple functions.

Bone tissue (osseous tissue), which is also called bone in the uncountable sense of that word, is hard tissue, a type of specialized connective tissue. It has a honeycomb-like matrix internally, which helps to give the bone rigidity. Bone tissue is made up of different types of bone cells. Osteoblasts and osteocytes are involved in the formation and mineralization of bone; osteoclasts are involved in the resorption of bone tissue. Modified (flattened) osteoblasts become the lining cells that form a protective layer on the bone surface. The mineralized matrix of bone tissue has an organic component of mainly collagen called ossein and an inorganic component of bone mineral made up of various salts. Bone tissue is mineralized tissue of two types, cortical bone and cancellous bone. Other types of tissue found in bones include bone marrow, endosteum, periosteum, nerves, blood vessels and cartilage.

In the human body at birth, there are approximately 300 bones present; many of these fuse together during development, leaving a total of 206 separate bones in the adult, not counting numerous small sesamoid bones. The largest bone in the body is the femur or thigh-bone, and the smallest is the stapes in the middle ear.

The Greek word for bone is "osteon", hence the many terms that use it as a prefix—such as osteopathy. In anatomical terminology, including the Terminologia Anatomica international standard, the word for a bone is os (for example, os breve, os longum, os sesamoideum).


Bone is a rigid body tissue consisting of cells embedded in an abundant hard intercellular material. The two principal components of this material, collagen and calcium phosphate, distinguish bone from such other hard tissues as chitin, enamel, and shell. Bone tissue makes up the individual bones of the human skeletal system and the skeletons of other vertebrates.

The functions of bone include (1) structural support for the mechanical action of soft tissues, such as the contraction of muscles and the expansion of lungs, (2) protection of soft organs and tissues, as by the skull, (3) provision of a protective site for specialized tissues such as the blood-forming system (bone marrow), and (4) a mineral reservoir, whereby the endocrine system regulates the level of calcium and phosphate in the circulating body fluids.

Evolutionary origin and significance

Bone is found only in vertebrates, and, among modern vertebrates, it is found only in bony fish and higher classes. Although ancestors of the cyclostomes and elasmobranchs had armoured headcases, which served largely a protective function and appear to have been true bone, modern cyclostomes have only an endoskeleton, or inner skeleton, of noncalcified cartilage and elasmobranchs a skeleton of calcified cartilage. Although a rigid endoskeleton performs obvious body supportive functions for land-living vertebrates, it is doubtful that bone offered any such mechanical advantage to the teleost (bony fish) in which it first appeared, for in a supporting aquatic environment great structural rigidity is not essential for maintaining body configuration. The sharks and rays are superb examples of mechanical engineering efficiency, and their perseverance from the Devonian Period attests to the suitability of their nonbony endoskeleton.

In modern vertebrates, true bone is found only in animals capable of controlling the osmotic and ionic composition of their internal fluid environment. Marine invertebrates exhibit interstitial fluid compositions essentially the same as that of the surrounding seawater. Early signs of regulability are seen in cyclostomes and elasmobranchs, but only at or above the level of true bone fishes does the composition of the internal body fluids become constant. The mechanisms involved in this regulation are numerous and complex and include both the kidney and the gills. Fresh and marine waters provide abundant calcium but only traces of phosphate; because relatively high levels of phosphate are characteristic of the body fluids of higher vertebrates, it seems likely that a large, readily available internal phosphate reservoir would confer significant independence of external environment on bony vertebrates. With the emergence of terrestrial forms, the availability of calcium regulation became equally significant. Along with the kidney and the various component glands of the endocrine system, bone has contributed to development of internal fluid homeostasis—the maintenance of a constant chemical composition. This was a necessary step for the emergence of terrestrial vertebrates. Furthermore, out of the buoyancy of water, structural rigidity of bone afforded mechanical advantages that are the most obvious features of the modern vertebrate skeleton.

Chemical composition and physical properties

Depending upon species, age, and type of bone, bone cells represent up to 15 percent of the volume of bone; in mature bone in most higher animals, they usually represent only up to 5 percent. The nonliving intercellular material of bone consists of an organic component called collagen (a fibrous protein arranged in long strands or bundles similar in structure and organization to the collagen of ligaments, tendons, and skin), with small amounts of proteinpolysaccharides, glycoaminoglycans (formerly known as mucopolysaccharides) chemically bound to protein and dispersed within and around the collagen fibre bundles, and an inorganic mineral component in the form of rod-shaped crystals. These crystals are arranged parallel with the long axes of collagen bundles and many actually lie in voids within the bundles themselves. Organic material constitutes 50 percent of the volume and 30 percent of the dry weight of the intercellular composite, with minerals making up the remainder. The major minerals of the intercellular composite are calcium and phosphate. When first deposited, mineral is crystallographically amorphous, but with maturation it becomes typical of the apatite minerals, the major component being hydroxyapatite. Carbonate is also present—in amounts varying from 4 percent of bone ash in fish and 8 percent in most mammals to more than 13 percent in the turtle—and occurs in two distinct phases, calcium carbonate and a carbonate apatite. Except for that associated with its cellular elements, there is little free water in adult mammalian bone (approximately 8 percent of total volume). As a result, diffusion from surfaces into the interior of the intercellular substance occurs at the slow rates more typical of diffusion from surfaces of solids than within liquids.

The mineral crystals are responsible for hardness, rigidity, and the great compressive strength of bone, but they share with other crystalline materials a great weakness in tension, arising from the tendency for stress to concentrate about defects and for these defects to propagate. On the other hand, the collagen fibrils of bone possess high elasticity, little compressive strength, and considerable intrinsic tensile strength. The tensile strength of bone depends, however, not on collagen alone but on the intimate association of mineral with collagen, which confers on bone many of the general properties exhibited by two-phase materials such as fibre glass and bamboo. In such materials the dispersion of a rigid but brittle material in a matrix of quite different elasticity prevents the propagation of stress failure through the brittle material and therefore allows a closer approach to the theoretical limiting strength of single crystals.

The fine structure of bone has thus far frustrated attempts to determine the true strength of the mineral-matrix composite at the “unit” structural level. Compact (cortical) bone specimens have been found to have tensile strength in the range of 700–1,400 kg per square cm (10,000–20,000 pounds per square inch) and compressive strengths in the range of 1,400–2,100 kg per square cm (20,000–30,000 pounds per square inch). These values are of the same general order as for aluminum or mild steel, but bone has an advantage over such materials in that it is considerably lighter. The great strength of bone exists principally along its long axis and is roughly parallel both to the collagen fibre axis and to the long axis of the mineral crystals.

Although apparently stiff, bones exhibit a considerable degree of elasticity, which is important to the skeleton’s ability to withstand impact. Estimates of modulus of elasticity of bone samples are of the order of 420 to 700 kg per square cm (6,000 to 10,000 pounds per square inch), a value much less than steel, for example, indicating the much greater elasticity of bone. Perfect elasticity exists with loads up to 30 to 40 percent of breaking strength; above this, “creep,” or gradual deformation, occurs, presumably along natural defects within the bony structure. The modulus of elasticity in bone is strikingly dependent upon the rate at which loads are applied, bones being stiffer during rapid deformation than during slow; this behaviour suggests an element of viscous flow during deformation.

As might be anticipated from consideration of the two-phase composition of bone, variation in the mineral-collagen ratio leads to changes in physical properties: less mineral tends ultimately to greater flexibility and more mineral to increased brittleness. Optimal ratios, as reflected in maximal tensile strength, are observed at an ash content of approximately 66 percent, a value that is characteristic of the weight-bearing bones of mammals.

Bone morphology

Grossly, bone tissue is organized into a variety of shapes and configurations adapted to the function of each bone: broad, flat plates, such as the scapula, serve as anchors for large muscle masses, while hollow, thick-walled tubes, such as the femur, the radius, and the ulna, support weight or serve as a lever arm. These different types of bone are distinguished more by their external shape than by their basic structure.

All bones have an exterior layer called cortex that is smooth, compact, continuous, and of varying thickness. In its interior, bony tissue is arranged in a network of intersecting plates and spicules called trabeculae, which vary in amount in different bones and enclose spaces filled with blood vessels and marrow. This honeycombed bone is termed cancellous or trabecular. In mature bone, trabeculae are arranged in an orderly pattern that provides continuous units of bony tissue aligned parallel with the lines of major compressive or tensile force. Trabeculae thus provide a complex series of cross-braced interior struts arranged so as to provide maximal rigidity with minimal material.

Bones such as vertebrae, subject to primarily compressive or tensile forces, usually have thin cortices and provide necessary structural rigidity through trabeculae, whereas bones such as the femur, subject to prominent bending, shear, or torsional forces, usually have thick cortices, a tubular configuration, and a continuous cavity running through their centres (medullary cavity).

Long bones, distinctive of the body’s extremities, exhibit a number of common gross structural features. The central region of the bone (diaphysis) is the most clearly tubular. At one or commonly both ends, the diaphysis flares outward and assumes a predominantly cancellous internal structure. This region (metaphysis) functions to transfer loads from weight-bearing joint surfaces to the diaphysis. Finally, at the end of a long bone is a region known as an epiphysis, which exhibits a cancellous internal structure and comprises the bony substructure of the joint surface. Prior to full skeletal maturity the epiphysis is separated from the metaphysis by a cartilaginous plate called the growth plate or physis; in bones with complex articulations (such as the humerus at its lower end) or bones with multiple protuberances (such as the femur at its upper end) there may be several separate epiphyses, each with its growth plate.

Additional Information:

Bones: All you need to know

Bones are more than just the scaffolding that holds the body together. Bones come in all shapes and sizes and have many roles. In this article, we explain their function, what they consist of, and the types of cells they involve.

Bones are living, active tissues that the body is constantly remodeling.

Their functions include supporting body structure, protecting vital organs, and allowing the body to move. Also, they provide an environment for bone marrow, where the body creates blood cells, and they act as a storage area for minerals, particularly calcium.

The skeleton accounts for around 15%Trusted Source of body weight. At birth, humans have around 270Trusted Source soft bones. As they grow, some fuse.

By adulthood, people have between 206 and 213 bones. The reason for the difference is that some people have more or fewer bones in their ribs, vertebrae, fingers, and toes.

The largest bone in the human body is the thighbone, or femur, and the smallest is the stapes in the middle ear, at around 3 millimetersTrusted Source long.

Bones consist mostly of the protein collagen, which forms a soft framework. The mineral calcium phosphate hardens this framework, giving it strength. The bones contain 99% of the body’s calcium.

Bones have an internal structure similar to a honeycomb, which makes them rigid yet relatively light.

The structure of bones

Bones are composed of two types.

Compact (cortical) bone is a hard outer layer that is dense, strong, and durable. It makes up around 80% of adult bone mass and forms the outer layer of bone.

Cancellous (trabecular or spongy) bone makes up the remaining 20% of bone and consists of a network of trabeculae, or rod-like, structures. It is lighter, less dense, and more flexible than compact bone.

Bones also contain:

* osteoblasts and osteocytes, responsible for creating bone
*vosteoclasts, or bone-resorbing cells
* osteoid, a mix of collagen and other proteins
* inorganic mineral salts within the matrix
*bnerves and blood vessels
* bone marrow
* cartilage
* membranes, including the endosteum and periosteum

Bone cells

Bones are not static tissue but need constant maintenance and remodeling. There are threeTrusted Source main cell types involved in this process.

Osteoblasts are responsible for generating and repairing bone. They produce a protein mixture that doctors call osteoid, which is mineralized and becomes bone.

Osteocytes are inactive osteoblasts that are mineralized and remain within the bone they have created. They communicate with other bone cells and help support metabolic functions within the bone.

Osteoclasts are large cells with more than one nucleus. They useTrusted Source acids resulting from certain reactions to break down used bone. This process is called resorption. Osteoclasts help remodel injured bones and create pathways for nerves and blood vessels to travel through.

Bone marrow

Bone marrow is present in almost all bones where cancellous, or spongy, bone is present.

Bone marrow produces blood cells, including:

* red blood cells, which deliver oxygen to cells
* white blood cells, essential for the body’s immune system
* platelets, which the body uses for clotting

The marrow produces around 2 million red blood cells every second. It also produces lymphocytes, or the white blood cells involved in the immune response.

Extracellular matrix

Bones are essentially living cells embedded in a mineral-based organic matrix. This extracellular matrix consists of organic components (mostly type 1 collagen) and inorganic components, including hydroxyapatite and other salts, such as calcium and phosphate.

Collagen gives bone its tensile strength, namely resistance to pulling apart. Hydroxyapatite gives the bones compressive strength, or resistance to compression.

What do bones do?

Bones serve various functions that affect the whole body. StudiesTrusted Source show that, in addition to structure and movement, bones support energy metabolism, the production of blood cells, the immune system, and brain function.


Bones provide a frame to support the body. Muscles, tendons, and ligaments attach to bones. Without anchoring to bones, muscles could not move the body.


Some bones protect the body’s internal organs. For instance, the skull protects the brain, and the ribs protect the heart and lungs.


Cancellous bone is a vital reservoir for developing red blood cells, platelets, and white blood cells. Also, the body destroys defective and old red blood cells in bone marrow.


The metabolic functions of bone include:

* Storage: Bones act as a reserve for minerals, particularly calcium and phosphorous. Bone marrow adipose tissue can also store fatty acids.
* Endocrine function: Bones produce the precursors to various hormones, including those involved in growth, insulin production, and brain development. They release hormones that act on the kidneys and influence blood sugar regulation and fat deposition.
* Calcium balance: Bones can raise or reduce calcium in the blood by forming bone, or breaking it down in a process called resorption.
* pH balance: Some research has suggested bones can release or absorb alkaline salts, helping blood to stay at the right pH level, but scientists need more studies to confirm this.
* Detoxification: Bones can absorbTrusted Source heavy metals such as lead, mercury, and math from the blood.

Types of bone

There are five types of bones in the human body:

* Long bones: These are mostly compacted bones with little marrow and include most of the bones in the limbs. They tend to support weight and help movement.
* Short bones: These have a squat, cubed shape and include bones of the wrist and ankle.
* Flat bones: These have a flat, broad surface. They consist of two outer layers of compact bone and an inner layer of spongy bone. The bones of the skull, breastbone, ribs, and shoulder blades are flat bones. They tend to have a protective role.
* Sesamoid bones: These are embeddedTrusted Source in muscles and tendons near the surfaces of joints. They include the patella or kneecap. They protect tendons from wear and stress.
* Irregular bones: These bones do not fit into the first four categories and have an unusual shape. They include the bones of the spine and pelvis. They often protect organs or tissues.

The bones of the skeleton belong to two groups: The appendicular and axial skeletons.

The appendicular skeleton comprises 126 bones, including those of the limbs, shoulders, and pelvic girdle. It provides structure and support to other parts of the body.

The axial skeleton has less range of motion than the appendicular skeleton. It comprises the bones of the skull, vertebral column, and thoracic cage.

Bone remodeling

The body is always remodeling bone. This allows the body to fix damaged bone, reshape the skeleton during growth, and regulate calcium levels.

Remodeling is a two-part process. During formation, the body lays down new bone tissue. In resorption, osteoclasts break down and remove bone.

If one part of the skeleton comes under increased stress over time — for instance, during exercise — the sections of bone under most pressure will become thicker in response.

Osteocytes, osteoclasts, and osteoblasts play key roles, but other elements also contribute. These include parathyroid hormone, vitamin D, estrogen, and testosterone.

What is osteoporosis?

Osteoporosis is a bone disease that involves a reductionTrusted Source in bone mineral density. This increases the risk of fractures.

It most commonly occurs in females after menopause. However, it can affect males too, and it can start before menopause.

Osteoporosis occurs either when removal or resorption of bone happens too quickly, new bone forms too slowly, or for both reasons.

Risk factors include:

* low calcium levels
* vitamin D deficiency
* smoking tobacco
* using corticosteroids
* a high alcohol intake

Screening can help prevent or slow the progression of osteoporosis. Tests can show that osteopenia, the early stage of osteoporosis, is present. At this point, a doctor may recommend dietary measures or supplements.

As bone deterioration worsens, medications are available to slow its progression.

What other bone diseases are there?

Recent research : Currently, researchers are looking into ways to regenerate bone. This could help people with osteoarthritis, osteoporosis, and other conditions. It could also help mend broken bones.

Bone regeneration is a complex process. Scientists are currently looking at various aspects, including ways to:

* speed up mineral production for the generation of new bone
* use natural or synthetic grafts to enhance bone healing
* scaffold new bone and allow growth to occur
* use artificial biomaterials to achieve bone regeneration
* stimulate nerve pathways to encourage authentic bone production
* regenerate bones with surfaces that allow for nutrient absorption
* use stem cells to encourageTrusted Source bone to regenerate

Frequently asked questions

Here are some answers to questions people often ask about bones:

Why are bones important for overall health?

Bones support the body’s structure and protect vital organs, but they also play a key role in blood cell production, the immune system, the storage of calcium, the release of essential hormones, and many other functions.

What things are important for bone health?

Following a varied diet with plenty of calcium, getting enough vitamin D, and exercising are important for bone health. Avoiding smoking and limiting alcohol intake can also help prevent osteoporosis.

How do you know if your bones are unhealthy?

Various health problems can affect the bones. Signs of osteoporosis include a loss of height, an increasingly stooped posture, and fractures that happen often or easily. A screening test can show if a person has reduced bone density.

Bone pain can be a sign of bone damage, infection, or bone cancer. Bones can become soft if there is a vitamin D deficiency. This can lead to bent shins in children, known as rickets. In adults, doctors call this osteomalacia.

A nontraumatic bone fracture in adults over 50 years old may also be an early sign of undiagnosed cancer, such as metastatic breast or lung cancer or multiple myeloma.

In short

Bones play an essential role in the structure and function of the human body.

As well as enabling movement, they maintain appropriate levels of many compounds. They regulate hormonal pathways, contribute to metabolism, support the immune system, and more.


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