Posts by Jai Ganesh

Jai Ganesh · This is Cool

Time Zone

Gist

Time zones divide the world into 24 segments, each about 15 degrees of longitude wide, to standardize time, as the Earth rotates 15 degrees every hour. They create uniform local times, offset from Coordinated Universal Time (UTC), allowing for synchronized schedules despite different sunrises/sunsets, with political boundaries often adjusting ideal 15-degree lines for practicality and some regions using Daylight Saving Time (DST).

Time zones are primarily based on the Earth's rotation and its division into 24 longitudinal sections, with each representing one hour of the day. The prime meridian, located at Greenwich, England (Greenwich Mean Time or GMT), serves as the starting point for defining time zones.

Summary

A time zone is an area which observes a uniform standard time for legal, commercial, and social purposes. Time zones tend to follow the boundaries between countries and their subdivisions instead of strictly following longitude, because it is convenient for areas in frequent communication to keep the same time.

Each time zone is defined by a standard offset from Coordinated Universal Time (UTC). The offsets range from UTC−12:00 to UTC+14:00, and are usually a whole number of hours, but a few zones are offset by an additional 30 or 45 minutes, such as in India and Nepal. Some areas in a time zone may use a different offset for part of the year, typically one hour ahead during spring and summer, a practice known as daylight saving time (DST).

Details

Time zone is a zone on the terrestrial globe that is approximately 15° longitude wide and extends from pole to pole and within which a uniform clock time is used. Time zones are the functional basis of standard time and were introduced in the late 19th century as railways connected places that had differing local times.

Different time zones occur because of the way in which Earth spins. Earth rotates 360 degrees every 24 hours, and therefore different parts of the planet experience daylight and darkness at different times. To coordinate time with daylight, the globe is divided into 24 segments, each 15 degrees of longitude apart. The prime meridian in Greenwich, England, serves as the starting point for these divisions, creating a global framework for timekeeping.

While the theoretical model of time zones is straightforward, practical adjustments are often made to accommodate political, social, and economic factors. For instance, some regions have chosen to adopt time offsets of 30 or 45 minutes instead of the standard one-hour difference. These adjustments are made to better align with local solar time or to unify time within a country, as seen in places such as Newfoundland, Iran, and India.

Before the concept of time zones, each locality set its time based on the Sun’s position, leading to a chaotic array of local times. This system became impractical with the advent of rapid railway transportation in the late 19th century, which required a more uniform timekeeping system to avoid confusion in scheduling. The introduction of standard time zones was a solution to this problem, allowing regions to adopt a consistent time standard.

International Date Line is an imaginary line extending between the North Pole and the South Pole and arbitrarily demarcating each calendar day from the next. It corresponds along most of its length to the 180th meridian of longitude but deviates eastward through the Bering Strait to avoid dividing Siberia and then deviates westward to include the Aleutian Islands with Alaska. South of the Equator, another eastward deviation allows certain island groups to have the same day as New Zealand.

The International Date Line is a consequence of the worldwide use of timekeeping systems arranged so that local noon corresponds approximately to the time at which the sun crosses the local meridian of longitude. A traveler going completely around the world while carrying a clock that he advanced or set back by one hour whenever he entered a new time zone and a calendar that he advanced by one day whenever his clock indicated midnight would find on returning to his starting point that the date according to his own experience was different by one day from that kept by persons who had remained at the starting point. The International Date Line provides a standard means of making the needed readjustment: travelers moving eastward across the line set their calendars back one day, and those traveling westward set theirs a day ahead.

Coordinated Universal Time (UTC) is the international basis of civil and scientific time, which was introduced on January 1, 1960. The unit of UTC is the atomic second, and UTC is widely broadcast by radio signals. These signals ultimately furnish the basis for the setting of all public and private clocks. Since January 1, 1972, UTC has been modified by adding “leap seconds” when necessary.

UTC serves to accommodate the timekeeping differences that arise between atomic time (which is derived from atomic clocks) and solar time (which is derived from astronomical measurements of Earth’s rotation on its axis relative to the Sun). UTC is thus kept within an exact number of seconds of International Atomic Time and is also kept within 0.9 second of the solar time denoted UT1. Because of the irregular slowing of Earth’s rate of rotation by tidal friction and other forces, there is now about one more (atomic clock-derived) second in a solar year than there are UT1 seconds. To remedy this discrepancy, UTC is kept within 0.9 second of UT1 by adding a leap second to UTC as needed; the last minute of December or June is made to contain 61 seconds. The slowing of Earth’s rotation varies irregularly, and so the number of leap seconds by which UTC must be retarded to keep it in epoch with UT1 cannot be predicted years in advance. Impending leap seconds for UTC are announced at least eight weeks in advance by the International Earth Rotation and Reference Systems Service at the Paris Observatory, however.

Universal Time (UT), the mean solar time of the Greenwich meridian (0° longitude). Universal Time replaced the designation Greenwich Mean Time in 1928; it is now used to denote the solar time (q.v. : quod vide : which see) when an accuracy of about one second suffices. In 1955 the International Astronomical Union defined several categories of Universal Time of successively increasing accuracy. UT0 represents the initial values of Universal Time obtained by optical observations of star transits at various astronomical observatories. These values differ slightly from each other because of the effects of polar motion (q.v.). UT1, which gives the precise angular coordinate of the Earth about its spin axis, is obtained by correcting UT0 for the effects of polar motion. Finally, an empirical correction to take account of annual changes in the Earth’s speed of rotation is added to UT1 to convert it into UT2. Coordinated Universal Time (q.v.), the international basis of civil and scientific time, is obtained from an atomic clock that is adjusted in epoch so as to remain close to UT1; in this way, the solar time that is indicated by Universal Time is kept in close coordination with atomic time.

Standard Time, the time of a region or country that is established by law or general usage as civil time.

The concept was adopted in the late 19th century in an attempt to end the confusion that was caused by each community’s use of its own solar time. Some such standard became increasingly necessary with the development of rapid railway transportation and the consequent confusion of schedules that used scores of different local times kept in separate communities. (Local time varies continuously with change in longitude.) The need for a standard time was felt most particularly in the United States and Canada, where long-distance railway routes passed through places that differed by several hours in local time. Sir Sandford Fleming, a Canadian railway planner and engineer, outlined a plan for worldwide standard time in the late 1870s. Following this initiative, in 1884 delegates from 27 countries met in Washington, D.C., and agreed on a system basically the same as that now in use.

The present system employs 24 standard meridians of longitude (lines running from the North Pole to the South Pole, at right angles to the Equator) 15° apart, starting with the prime meridian through Greenwich, England. These meridians are theoretically the centres of 24 Standard Time zones, although in practice the zones often are subdivided or altered in shape for the convenience of inhabitants; a notable example of such alteration is the eastward extension of the International Date Line around the Pacific island country of Kiribati. Time is the same throughout each zone and differs from the international basis of legal and scientific time, Coordinated Universal Time, by an integral number of hours; minutes and seconds are the same. In a few regions, however, the legal time kept is not that of one of the 24 Standard Time zones, because half-hour or quarter-hour differences are in effect there. In addition, Daylight Saving Time is a common system by which time is advanced one hour from Standard Time, typically to extend daylight hours during conventional waking time and in most cases for part of the year (usually in summer).

Additional Information

Data spotlights represent data and statistics from a specific period of time, and do not reflect ongoing data collection. As individual spotlights are static stories, they are not subject to the Bureau of Transportation Statistics (BTS) web standards and may not be updated after their publication date. Please contact BTS to request updated information.

Before the establishment of time zones in 1883, there were more than 144 local times in North America. The resulting time differences between adjacent towns and cities were not critical when it took days to travel from place to place. With the proliferation of railroads, faster travel became possible across large geographies, and travelers could sometimes arrive at an earlier local time than they had departed. Due to this lack of time standardization, train scheduling proved difficult to coordinate, resulting in missed connections and collisions. As a result, the major railroad companies began to operate on a coordinated system of four time zones starting in 1883.

Because the development of standardized time was transportation-driven, the government coordination of time zones was handled by transportation agencies. In 1918, the federal organization in charge of railroad regulation — the Interstate Commerce Commission (ICC) — was given the power to address coordination concerns. That year, five time zones were officially adopted as the US entered World War I: the Eastern, Central, Mountain, Pacific, and Alaska zones, all of which are still in use today. However, the need for coordination among all transportation modes became increasingly important after World War II. When the Department of Transportation was created by Congress in 1966, it was assigned “the responsibility of regulating, fostering, and promoting widespread and uniform adoption and observance of standardized time” within each time zone.

Daylight Saving Time (DST) was enacted as a legal requirement by the Uniform Time Act of 1966. Motivated by transportation improvements, this act mandated standard time within the existing time zones and established a permanent system of uniform DST, including the dates and times for twice yearly transitions. While State governments cannot independently change time zones or the length of DST, they can exempt themselves from DST, independent of DOT authority or permission. Nonetheless, DST is observed uniformly across the nation except in American Samoa, Guam, Northern Mariana Islands, Puerto Rico, the Virgin Islands, Hawaii, and most of Arizona.

Today, the Department of Transportation continues to oversee standard time due to its historical and contemporary importance in transportation and associated commercial activity. Time zone boundaries, established by law, can only be changed by the Secretary of Transportation upon a determination that the proposed adjustment serves the “convenience of commerce.” Per DOT policy, a petition requesting such a change must come from the highest political authorities in a State or locality. Several communities have requested changes to their time zone designation over the past two decades, the most recent being Mercer County, North Dakota in 2010, which chose to switch from Mountain to Central Time. Authorizing these changes and keeping track of the legally designated time zone for each area of the U.S. are key facets of the DOT’s oversight of uniform time observance, time zones, and DST.

In 2019, the Bureau of Transportation Statistics (BTS), in coordination with the Office of the General Counsel, created a digital geographic representation of the official written time zone delineations defined in the Code of Federal Regulations (CFR), Title 49, Subtitle A, Part 71 - Standard Time Zone Boundaries. Currently the United States and its territories have 9 time zone boundaries: Atlantic, Eastern, Central, Mountain, Pacific, Alaska, Hawaii–Aleutian, Samoa, and Chamorro.

The DOT Time Zone Boundary Geospatial layer is the verified digital representation of the current time zone delineations as written in the CFR, and is part of the National Transportation Atlas Database (NTAD). This layer provides the American public with detailed, reliable, and authoritative information on time-related authorities and time zone boundaries.

Jai Ganesh · This is Cool

2483) Mauritius

Gist

Mauritius is geographically an African island nation in the Indian Ocean, but its majority population (around two-thirds) has Indian ancestry, making it a unique blend of African geography and significant Indian cultural/ethnic influence, with Hinduism being the dominant religion, unlike other African nations.

Mauritius is famous for its stunning tropical scenery with beaches, lagoons, and volcanic mountains, making it a top honeymoon and luxury travel spot, but it's also known for its unique history as the only home of the extinct dodo bird, its rich multicultural heritage (Indian, African, Chinese, European), diverse cuisine, vibrant underwater life for diving, rare endemic wildlife (like the Mauritius kestrel), and UNESCO World Heritage sites like Aapravasi Ghat and Le Morne.

Summary

Mauritius, island country in the Indian Ocean, located off the eastern coast of Africa. Physiographically, it is part of the Mascarene Islands. The capital is Port Louis.

Land

Mauritius lies about 500 miles (800 km) east of Madagascar in the Indian Ocean. Its outlying territories are Rodrigues Island, situated about 340 miles (550 km) eastward, the Cargados Carajos Shoals, 250 miles (400 km) northeastward, and the Agalega Islands, 580 miles (930 km) northward from the main island. Mauritius also claims sovereignty over the Chagos Archipelago (including Diego Garcia), some 1,250 miles (2,000 km) to the northeast, although this claim was long disputed by Britain. A tentative agreement between Mauritius and Britain to resolve the competing claims was announced in October 2024, and a final agreement to cede sovereignty to Mauritius was signed in May 2025.

Capital: Port Louis
Population: (2025 est.) 1,232,000
Currency Exchange Rate: 1 USD equals 45.660 Mauritian rupee

Relief and drainage

The island of Mauritius is volcanic in origin and is almost entirely surrounded by coral reefs. The northern part is a plain that rises to a central plateau, varying in elevation from about 900 to 2,400 feet (270 to 730 meters) above sea level. The plateau is bordered by small mountains that may have formed the rim of an ancient volcano; the highest point (2,717 feet [828 meters]) is Piton de la Petite Rivière Noire in the southwest. The two major rivers, the Grand River South East and the Black River, are the primary sources of hydroelectric power. Lake Vacoas, one of the main reservoirs, is the chief source of water.

Soils and climate

More than half of the country’s area is arable, and it is almost entirely planted in sugarcane, the major export crop. Vegetables and tea for local consumption are also grown.

The climate is maritime subtropical, with fairly uniform temperature throughout the year. Mean temperatures vary from the mid-70s F (low to mid-20s C) at sea level to the upper 60s F (upper 10s C) on the high plateau. Two seasons are recognized: hot (December to April) and cool (June to September). Annual rainfall varies from around 35 inches (900 mm) on the west coast to 60 inches (1,525 mm) on the southeast coast and about 200 inches (5,080 mm) on the central plateau.

Plant and animal life

The vegetation includes some 600 indigenous species, even though little original forest is left. The fauna includes the samber (a long-tailed, dark brown deer), tenrec (a spiny insectivore), and mongoose, as well as a variety of birds and insects. The island was once home to the dodo, a flightless bird that was extinct by 1681. Efforts began in the late 20th century to save several other species of endemic birds that were close to extinction.

Details

Mauritius, officially the Republic of Mauritius, is an island nation in the Indian Ocean, about 2,000 kilometres (1,100 nautical miles) off the southeastern coast of East Africa, east of Madagascar. It includes the main island (also called Mauritius), as well as Rodrigues, Agaléga, St. Brandon (Cargados Carajos shoals). The islands of Mauritius and Rodrigues, along with nearby Réunion (a French overseas department), are part of the Mascarene Islands. The main island of Mauritius, where the population is concentrated, hosts the capital and largest city, Port Louis. The country spans 2,040 square kilometres (790 sq mi) and has an exclusive economic zone covering approximately 2,000,000 square kilometres (580,000 square nautical miles).

The 1502 Portuguese Cantino planisphere has led some historians to speculate that Arab sailors were the first to discover the uninhabited island around 975, naming it Dina Arobi. Called Ilha do Cirne or Ilha do Cerne on early Portuguese maps, the island was visited by Portuguese sailors in 1507. A Dutch fleet, under the command of Admiral Van Warwyck, landed at what is now the Grand Port District and took possession of the island in 1598, renaming it after Maurice, Prince of Orange. Short-lived Dutch attempts at permanent settlement took place over a century aimed at exploiting the local ebony forests, establishing sugar and arrack production using cane plant cuttings from Java together with over three hundred Malagasy slaves, all in vain. When French colonisation began in 1715, the island was renamed "Isle de France". In 1810, the United Kingdom seized the island and under the Treaty of Paris, France ceded Mauritius and its dependencies to the United Kingdom. The British colony of Mauritius now included Rodrigues, Agaléga, St. Brandon, the Chagos Archipelago, and, until 1906, the Seychelles. Mauritius and France dispute sovereignty over the island of Tromelin, the treaty failing to mention it specifically. Mauritius became the British Empire's main sugar-producing colony and remained a primarily sugar-dominated plantation-based colony until independence, in 1968. In 1992, the country abolished the monarchy, replacing it with the president.

In 1965, three years before the independence of Mauritius, the United Kingdom split the Chagos Archipelago away from Mauritius, and the islands of Aldabra, Farquhar, and Desroches from the Seychelles, to form the British Indian Ocean Territory (BIOT). The local population was forcibly expelled and the largest island, Diego Garcia, was leased to the United States restricting access to the archipelago. Ruling on the sovereignty dispute, the International Court of Justice has ordered the return of the Chagos Islands to Mauritius leading to a 2025 bilateral agreement on the recognition of its sovereignty on the islands, signed in May 2025.

Given its geographic location and colonial past, the people of Mauritius are diverse in ethnicity, culture, language and faith. It is the only country in Africa where Hinduism is the most practised religion. Indo-Mauritians make up the bulk of the population with significant Creole, Sino-Mauritian and Franco-Mauritian minorities. The island's government is closely modelled on the Westminster parliamentary system with Mauritius highly ranked for economic and political freedom. The Economist Democracy Index ranks Mauritius as the only country in Africa with full democracy while the V-Dem Democracy Indices classified it as an electoral autocracy. Mauritius ranks 73rd (very high) in the Human Development Index and the World Bank classifies it as a high-income economy. It is amongst the most competitive and most developed economies in the African region. The country is a welfare state. The government provides free universal health care, free education up through the tertiary level, and free public transportation for students, senior citizens, and the disabled. Mauritius is consistently ranked as the most peaceful country in Africa.

Along with the other Mascarene Islands, Mauritius is known for its biodiverse flora and fauna with many unique species endemic to the country. The main island was the only known home of the dodo, which, along with several other avian species, became extinct soon after human settlement. Other endemic animals, such as the echo parakeet, the Mauritius kestrel and the pink pigeon, have survived and are subject to intensive and successful ongoing conservation efforts.

Additional Information

Mauritius is a stable and prosperous Indian Ocean archipelago.

Once dependent on sugar exports, the island has built up a strong outsourcing and financial services sector, as well as an important tourism industry, and now boasts one of Africa's highest per capita incomes.

In the 1960s, hundreds of inhabitants of the Chagos Islands, over which Mauritius claimed sovereignty, were deported to make way for a US military base on the island of Diego Garcia.

The islands had been administered as part of Mauritius from the 18th Century onwards. In 1965, shortly before Mauritian independence the UK separated them along with Aldabra, Farquhar and Desroches in the Seychelles to form the British Indian Ocean Territory.

The latter three islands were returned to Seychelles in 1976 on its independence.

In 2024, after years of negotiations, the UK announced it would hand sovereignty of the Chagos Islands back to Mauritius.

This included the tropical atoll of Diego Garcia, used by the US government as a military base for its navy ships and long-range bomber aircraft.

The US-UK base remains on Diego Garcia - this was a key factor enabling the deal to go forward at a time of growing geopolitical rivalries in the region between Western countries, India, and China.

_129049063_bbcm_mauritius_country_profile_map_160323.png.webp

Jai Ganesh · Dark Discussions at Cafe Infinity

2421) Emilio Segrè

Gist:

Work

The matter around us has a kind of mirror image—antimatter. A particle and its antiparticle have an opposite electrical charge, among other things. The electron’s antiparticle positron was the first to be discovered. With high concentrations of energy, a pair of particles and antiparticles can be created, but when a particle and an antiparticle meet, both are annihilated and their mass is converted into radiation. In a 1955 experiment with a powerful particle accelerator, Emilio Segrè and Owen Chamberlain confirmed the existence of the proton’s antiparticle, the antiproton.

Summary

Emilio Gino Segrè (1 February 1905 – 22 April 1989) was an Italian-American nuclear physicist and radiochemist who discovered the elements technetium and astatine, and the antiproton, a subatomic antiparticle, for which he was awarded the Nobel Prize in Physics in 1959, along with Owen Chamberlain.

Born in Tivoli, near Rome, Segrè studied engineering at the University of Rome La Sapienza before taking up physics in 1927. Segrè was appointed assistant professor of physics at the University of Rome in 1932 and worked there until 1936, becoming one of the Via Panisperna boys. From 1936 to 1938 he was director of the Physics Laboratory at the University of Palermo. After a visit to Ernest O. Lawrence's Berkeley Radiation Laboratory, he was sent a molybdenum strip from the laboratory's cyclotron accelerator in 1937, which was emitting anomalous forms of radioactivity. Using careful chemical and theoretical analysis, Segrè was able to prove that some of the radiation was being produced by a previously unknown element, named technetium, the first artificially synthesized chemical element that does not occur in nature.

In 1938 and while Segrè was visiting the Berkeley Radiation laboratory, Benito Mussolini's fascist government passed antisemitic laws barring Jews from university positions. As a Jew, Segrè was rendered an indefinite émigré. At the Berkeley Radiation Lab, Lawrence offered him an underpaid job as a research assistant. There, Segrè helped discover the element astatine and the isotope plutonium-239, which was later used to make the Fat Man nuclear bomb dropped on Nagasaki. From 1943 to 1946 he worked at the Los Alamos National Laboratory as a group leader for the Manhattan Project. He found in April 1944 that Thin Man, the proposed plutonium gun-type nuclear weapon, would not work due to the presence of plutonium-240 impurities. In 1944, he became a naturalized citizen of the United States. On his return to Berkeley in 1946, he became a professor of physics and of history of science, serving until 1972. Segrè and Owen Chamberlain co-headed a research group at the Lawrence Radiation Laboratory that discovered the antiproton, for which the two shared the 1959 Nobel Prize in Physics.

Segrè was an active photographer who took many pictures documenting events and people in the history of modern science, which were donated to the American Institute of Physics after his death. The American Institute of Physics named its photographic archive of physics history in his honor.

Details

Emilio Segrè (born January 30, 1905, Tivoli, Italy—died April 22, 1989, Lafayette, California, U.S.) was an Italian-born American physicist who, with Owen Chamberlain, received the Nobel Prize for Physics in 1959 for the discovery of the antiproton, an antiparticle having the same mass as a proton but opposite in electrical charge.

Segrè initially began studies in engineering at the University of Rome in 1922 but later studied under Enrico Fermi and received his doctorate in physics in 1928. In 1932 Segrè was appointed assistant professor of physics at the University of Rome, and two years later he participated in neutron experiments directed by Fermi, in which many elements, including uranium, were bombarded with neutrons, and elements heavier than uranium were created. In 1935 they discovered slow neutrons, which have properties important to the operation of nuclear reactors.

Emilio Segrè was born on January 30, 1905, but government records say otherwise. “My father reported my arrival to the civil authorities later than prescribed by law,” Segrè wrote in his autobiography, “and to avoid complications, I was registered as having been born on February 1, which became my official birthday.”

Segrè left Rome in 1936 to become director of the physics laboratory at the University of Palermo. One year later he discovered technetium, the first element to be artificially produced. While visiting California in 1938, Segrè was dismissed from the University of Palermo by the Fascist government, so he remained in the United States as a research associate at the University of California, Berkeley. Continuing his research, he and his associates discovered the element astatine in 1940, and later, with another group, he discovered the isotope plutonium-239, which he found to be fissionable, much like uranium-235. Plutonium-239 was used in the first atomic bomb and in the bomb dropped on Nagasaki.

From 1943 to 1946 Segrè was a group leader at the Los Alamos Scientific Laboratory in Los Alamos, New Mexico. He was naturalized as a U.S. citizen in 1944 and became professor of physics at Berkeley (1946–72). In 1955, using the new bevatron particle accelerator, Segrè and Chamberlain produced and identified antiprotons and thus set the stage for the discovery of many additional antiparticles. He was appointed professor of nuclear physics at the University of Rome in 1974.

Segrè wrote several books, including Experimental Nuclear Physics (1953), Nuclei and Particles (1964), Enrico Fermi: Physicist (1970), and two books on the history of physics, From X-rays to Quarks: Modern Physicists and Their Discoveries (1980) and From Falling Bodies to Radio Waves (1984). His autobiography, A Mind Always in Motion, was published posthumously, in 1993.

Shortly after winning the Nobel Prize, Segrè wrote the entry on the proton for the 1960 printing of the 14th edition of the Encyclopædia Britannica.

Jai Ganesh · This is Cool

Civet

Gist

Is a civet a type of cat?

No, a civet is not a cat, but a nocturnal mammal from the Viverridae family, closely related to mongooses and hyenas, despite its cat-like appearance that earns it the misnomer "civet cat". They have longer snouts, shorter legs, and different feet than true cats (felines), belonging to the broader suborder Feliformia, which includes both cats and viverrids.

Civets are territorial creatures, utilizing scent marking to communicate and defend their territory. While generally shy and elusive, they can become aggressive if cornered or threatened.

Summary

A civet is any of a number of long-bodied, short-legged carnivores of the family Viverridae. There are about 15 to 20 species, placed in 10 to 12 genera. Civets are found in Africa, southern Europe, and Asia. Rather catlike in appearance, they have a thickly furred tail, small ears, and a pointed snout. The coloration varies widely among the species but commonly is buff or grayish with a pattern of black spots or stripes or both. Length ranges from about 40 to 85 cm (16 to 34 inches), with the tail accounting for another 13 to 66 cm (5 to 26 inches), and weight ranges from 1.5 to 11 kg (3.3 to 24 pounds).

Civets are usually solitary and live in tree hollows, among rocks, and in similar places, coming out to forage at night. Except for the arboreal palm civets, such as Paradoxurus (also known as toddy cat because of its fondness for palm juice, or “toddy”) and Nandinia, civets are mainly terrestrial. The Sunda otter civet (Cynogale bennetti), the African civet (Civettictis civetta), and the rare Congo water civet (Genetta piscivora) are semiaquatic. Civets feed on small animals and on vegetable matter. Their litters usually consist of two or three young.

The anal glands of civets open under the tail into a large pouch in which a greasy, musklike secretion accumulates. This secretion, known as civet, is used by the animals in marking territories. The secretion of the small Indian civet, or rasse (Viverricula indica), and of the Oriental civets (Viverra) is employed commercially in the manufacture of perfume. In addition, coffee beans fermented within and excreted from the digestive tracts of civets in the Philippines and Indonesia are sometimes used to enhance the taste of coffee.

The IUCN Red List of Threatened Species lists several civets in danger of extinction; among these are the Malabar civet (Viverra civettina), which lives in the Western Ghats of India, and the Sunda otter civet, which is native to the Malay Peninsula, Sumatra, and Borneo.

Details

A civet is a small, lean, mostly nocturnal mammal native to tropical Asia and Africa, especially the tropical forests. The term civet applies to over a dozen different species, mostly from the family Viverridae. Most of the species's diversity is found in southeast Asia. Civets do not form a monophyletic group, as they consist only of certain members of the Viverridae and Eupleridae.

The African civet, Civettictis civetta, has historically been the main species from which a musky scent used in perfumery, also referred to as "civet", was obtained.

Physical characteristics

Civets have a broadly cat-like general appearance, though the muzzle is extended and often pointed, rather like that of an otter, mongoose or even possibly a ferret. They range in length (excluding the tail) from around 43 to 71 cm (17 to 28 in) and in weight from around 1.4 to 4.5 kg (3 to 10 lb).

The civet produces a musk (named civet after the animal) which is highly valued as a fragrance and stabilizing agent for perfume. Both male and female civets produce the strong-smelling secretion, which is produced by the civet's perineal glands. It is harvested by either killing the animal and removing the glands, or by scraping the secretions from the glands of a live animal. The latter is the preferred method today.

Animal rights groups, such as World Animal Protection, express concern that harvesting musk is cruel to animals. Between these ethical concerns and the availability of synthetic substitutes, the practice of raising civets for musk is dying out. Chanel, maker of the popular perfume Chanel No. 5, claims that natural civet has been replaced with a synthetic substitute since 1998.

Habitat

Viverrids are native to sub-Saharan Africa, Madagascar, the Iberian Peninsula, southern China, South and Southeast Asia. Favoured habitats include woodland, savanna, and mountain biome. In consequence, many are faced with severe loss of habitat; several species are considered vulnerable and the otter civet is classified as endangered. Some species of civet are very rare and elusive and hardly anything is known about them, e.g., the Hose's civet, endemic to the montane forests of northern Borneo, is one of the world's least known carnivores.

Relationship with humans

The Malayan civet is found in many habitats, including forests, secondary habitats, cultivated land, and the outskirts of villages; the species is highly adaptable to human disturbances, including "selective logging" (partial forest removal).

African civets (Civettictis civetta) are listed as Least Concern. However, in certain regions of Africa, the population is declining; this is due to hunting, direct and indirect poisoning, and an increase in large-scale farm fences that limit population flow. They are also seen as comparatively abundant options in the bushmeat trade.

Masked palm civets sold for meat in local markets of Yunnan China, carried the SARS virus from horseshoe bats to humans; this resulted in the 2002–2004 SARS outbreak.

Civets are also raised in captivity by humans for two reasons. In Asia, they are raised to process coffee beans. In Ethiopia, they are raised in captivity to collect their perineal secretions, also called civet, to be used in making perfume.

Urban environments

Palm civets often venture into cities and suburbs, with people often complaining about civet faeces and the noise of the animals' climbing on roofs. Some studies have been undertaken to examine and mitigate such human–animal conflict.

Literature

In William Shakespeare's As You Like It, act II, scene 2, the civet cat is mentioned as the "uncleanly" source of courtiers' perfumes.

original-6-edited.jpg?resize=1536,866

Jai Ganesh · Science HQ

Sternum

Gist

The sternum, or breastbone, is a flat, vertical bone in the center of the chest that forms the front of the rib cage, protecting vital organs like the heart and lungs, and serving as an attachment point for ribs and muscles. It's divided into three parts—the manubrium, body, and xiphoid process—and is crucial for chest stability and breathing.

The sternum is also commonly known as the breastbone, a flat bone in the center of the chest that connects the ribs and protects vital organs like the heart and lungs. Anatomically, it's divided into three parts: the manubrium, the body (or gladiolus), and the xiphoid process.

Summary

The sternum (pl.: sternums or sterna) or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Shaped roughly like a necktie, it is one of the largest and longest flat bones of the body. Its three regions are the manubrium, the body, and the xiphoid process.

Structure

The sternum is a narrow, flat bone, forming the middle portion of the front of the chest. The top of the sternum supports the clavicles (collarbones) and its edges join with the costal cartilages of the first two pairs of ribs. The inner surface of the sternum is also the attachment of the sternopericardial ligaments. Its top is also connected to the sternocleidomastoid muscle. The sternum consists of three main parts, listed from the top:

* Manubrium
* Body (gladiolus)
* Xiphoid process

In its natural position, the sternum is angled obliquely, downward and forward. It is slightly convex in front and concave behind; broad above, shaped like a "T", becoming narrowed at the point where the manubrium joins the body, after which it again widens a little to below the middle of the body, and then narrows to its lower extremity. It is usually longer in the male than in the female.

Details

Your sternum, or breastbone, is a flat, vertical bone at the center of your chest that protects your organs and muscles. It connects to other bones and muscles and forms part of your ribcage, which protects your heart and lungs. Many different conditions can cause sternum pain, but most aren’t serious.

Overview:

What is the sternum?

Your sternum is a flat, T-shaped bone at the center and front of your chest. Your sternum protects the organs and muscles inside your chest from injury. It also connects to other bones and muscles with cartilage. It forms part of your ribcage, which protects your heart and lungs. Another name for your sternum bone is your breastbone.

Function:

What is the function of the sternum in the ribcage?

Your sternum (breastbone) works with your ribcage to protect the organs within your chest. This includes your:

* Stomach.
* Esophagus.
* Lungs.
* Heart.
* Blood vessels.

Your breastbone also provides support — it connects to other parts of your skeletal system, including your clavicle (collarbone) and first six sets of ribs. Other muscles in your chest and upper belly (abdomen) connect to your sternum, as well.

Your sternum doesn’t help with movement in your chest or torso. But cartilage that connects your sternum to your ribs helps with minor motions that occur every time you take a breath.

Anatomy:

Where is the sternum?

The breastbone location is at the center and front of your chest. You can find it in your upper chest in front of your thymus. It connects to your clavicles, which run horizontally (from side to side) above it.

What organ is behind your sternum?

Your thymus gland is located behind your sternum (breastbone). This gland is part of your lymphatic system. It’s in charge of training special white blood cells called T-lymphocytes (T-cells).

What are the parts of the sternum?

Your sternum anatomy consists of three bony parts. These parts include:

* Manubrium: The manubrium of the sternum is the wide, handle-like top portion of the bone. This is where your collarbone and first set of ribs attach. The bottom edge of the manubrium borders the body of your sternum, which is where your second set of ribs attach.
* Body: The body of the sternum is in the center. It’s flat, narrow and the longest part of your sternum. Your third, fourth, fifth, sixth and seventh set of ribs attach to your sternum along the body.
* Xiphoid process: The xiphoid process is the lowest part of the sternum. This pointed end piece of your sternum is made of mostly cartilage. As you age, it begins to calcify and turn to bone.

What is the tip of the sternum?

The tip of the sternum is called the xiphoid process. It’s thinner and narrower than the rest of the sternum. Its shape can vary, but it usually forms into a small point at the bottom of the sternum.

What does the sternum look like?

Your sternum measures about 6 inches long from top to bottom. You could compare the shape of your sternum to an upside-down sword. This is because the wide part at the top resembles a handle. The body of the sternum is long and flat, like the blade of a sword. And the xiphoid process at the end of the sternum looks like the tip of a sword.

Conditions and Disorders:

What does it mean when your sternum hurts?

Many issues with your sternum and its surrounding bones and muscles can cause sternum pain. In addition, you may experience substernal pain — discomfort that occurs below or behind your sternum. This type of pain is usually due to gastrointestinal conditions. Some common causes of sternum or substernal pain include:

* Costochondritis.
* Pectus carinatum.
* Sternum (sternal) fracture.
* Sternoclavicular joint injury.
* Collarbone injury.
* Muscle strain.
* Hiatal hernia.
* Acid reflux.
* Pleurisy.
* Bronchitis.
* Pneumonia.

Costochondritis

Costochondritis is a condition that causes inflammation in the cartilage that attaches your ribs to your sternum. An infection, injury or arthritis can cause the condition. Costochondritis causes sharp, stabbing rib pain and tenderness. You usually feel it in your sternal area and the first three sets of ribs, but it can spread to your arms and shoulders. You may also notice warmth and tenderness in the area.

Pectus carinatum

Pectus carinatum is a condition that causes your sternum to stick out more than it should. Other names for the condition include pigeon chest and keel chest because of how it makes your chest appear. Most people with pectus carinatum don’t have symptoms. But, you may experience chest pain when in specific positions or participating in certain activities.

Sternum (sternal) fracture

A sternal fracture occurs when you break your sternum bone, most often due to blunt force trauma. Sternum fractures commonly occur due to auto accidents. They also happen because of sports injuries and falls. There are two types of sternum fractures:

* Direct: When a direct blow to the front of your chest wall causes a break further back in your chest.
* Indirect: When your sternum is injured in such a way that a break occurs closer to the front of your chest.

Sternoclavicular joint injury

Your sternoclavicular joint is the area in your body where your clavicle connects to your sternum. Although rare, you can sometimes develop problems in this joint area due to infections, injuries or arthritis. You’ll experience pain and discomfort if you have an injury there.

Collarbone injury

Your collarbone (clavicle) connects to the top corners of your sternum. Since the two are closely connected, if you injure your collarbone, you’ll feel pain and discomfort in your sternum, as well. You can injure your collarbone through accidents, sports injuries and falls.

Muscle strain

A muscle strain, or a pulled muscle, can occur when you injure a tendon or muscle. Many tendons and muscles are connected to your sternum. Therefore, injuries to a muscle or tendon can also affect your sternum. Muscle strains occur due to overuse, playing sports and coughing too hard.

Hiatal hernia

A hiatal hernia happens when the top of your stomach moves past your diaphragm and into your chest. This affects the area behind your chest and can cause substernal pain (the area behind your sternum). Hiatal hernias are the most common type of hernia.

Acid reflux

Acid reflux occurs when stomach acid causes irritation and inflammation that wears away the lining of your esophagus. This can cause substernal pain. The condition most often affects people with gastroesophageal reflux disease (GERD).

Pleurisy

Pleurisy is a condition that causes inflammation in your pleurae — the sheets of tissue between your ribcage and lungs. Some autoimmune diseases, lung conditions, and bacterial or viral infections can cause pleurisy. This can also cause substernal pain.

Bronchitis

Bronchitis is a condition that causes inflammation in the primary airways leading to your lungs — your trachea (windpipe) and bronchi — causing substernal pain. This inflammation causes your lungs to fill with mucus, leaving you with a nagging cough that can last for weeks.

Pneumonia

Pneumonia is a condition that causes inflammation in the air sacs (alveoli) in your lungs. After the alveoli inflame, they fill with fluid, which can cause sharp chest pains. You may feel this pain behind your sternum.

Additional Information

Sternum, in the anatomy of tetrapods (four-limbed vertebrates), is an elongated bone in the centre of the chest that articulates with and provides support for the clavicles (collarbones) of the shoulder girdle and for the ribs. Its origin in evolution is unclear. A sternum appears in certain salamanders; it is present in most other tetrapods but lacking in legless lizards, snakes, and turtles (in which the shell provides needed support). In birds an enlarged keel develops, to which flight muscles are attached; the sternum of the bat is also keeled as an adaptation for flight.

In mammals the sternum is divided into three parts, from anterior to posterior: (1) the manubrium, which articulates with the clavicles and first ribs; (2) the mesosternum, often divided into a series of segments, the sternebrae, to which the remaining true ribs are attached; and (3) the posterior segment, called the xiphisternum. In humans the sternum is elongated and flat; it may be felt from the base of the neck to the pit of the abdomen. The manubrium is roughly trapezoidal, with depressions where the clavicles and the first pair of ribs join. The mesosternum, or body, consists of four sternebrae that fuse during childhood or early adulthood. The mesosternum is narrow and long, with articular facets for ribs along its sides. The xiphisternum is reduced to a small, usually cartilaginous xiphoid (“sword-shaped”) process. The sternum ossifies from several centres. The xiphoid process may ossify and fuse to the body in middle age; the joint between manubrium and mesosternum remains open until old age.

Jai Ganesh · Dark Discussions at Cafe Infinity

Combat Quotes - II

1. From when I was a young boy, I read books on weapons and tanks and combat. I was so interested in the army. - MS Dhoni

2. When I arrive at my destination, I like to hit the gym, as I find exercise helps combat jet lag. - Orlando Bloom

3. We aim to encourage investments that ease our supply-side bottlenecks, such as rural roads, cold-storage, and grain-warehouses, which will also help us combat inflation. - Piyush Goyal

4. Our combat mission is ending, but our commitment to Iraq's future is not. - Barack Obama

5. Let's not leave an educational vacuum to be filled by religious extremists who go to families who have no other option and offer meals, housing and some form of education. If we are going to combat extremism then we must educate those very same children. - Hillary Clinton

6. The important thing in life is not victory but combat; it is not to have vanquished but to have fought well. - Pierre de Coubertin

7. Doing all we can to combat climate change comes with numerous benefits, from reducing pollution and associated health care costs to strengthening and diversifying the economy by shifting to renewable energy, among other measures. - David Suzuki

8. As every new breed of virus is conceived, created and released into the wild, another small change is made to the anti-virus software to combat the new threat. - Glenn Turner.

Jai Ganesh · Jokes

Q: What is brown, hairy, and wears sunglasses?
A: A coconut on vacation.
* * *
Q: What do you call a fruit that goes into space?
A: A coco-naut.
* * *
Q: Where do intergalactic coconuts grab a drink?
A: At the "Milky Way".
* * *
Q: What do you call people who like to drink hot chocolate all year long?
A: Cocoa-Nuts.
* * *
Q: What did one coconut say to the other?
A: Got milk?
* * *

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#10723. What does the term in Geography Cove mean?

#10724. What does the term in Geography Crater mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#2556. What does the medical term Cushing's syndrome mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#5919. What does the adjective granular mean?

#5920. What does the noun grapnel mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#9841.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#6335.

Jai Ganesh · Exercises

Hi,

2692.

Jai Ganesh · Dark Discussions at Cafe Infinity

2420) Peter Medawar

Gist:

Work

Our immune system protects us against attacks by microorganisms and rejects foreign tissue. Part of our immunity has a hereditary basis, but part of it is acquired and is not present in the fetus. After Macfarlane Burnet theorized that the ability to distinguish between one’s own and foreign tissue is acquired during the fetus stage, Peter Medawar successfully transplanted tissue between mouse fetuses without rejection in 1951. He could perform new transplants on the mice when they became adults, something that did not work when the transplants were not performed during the fetus stage. The results had significance for organ transplants.

Summary

Sir Peter B. Medawar (born Feb. 28, 1915, Rio de Janeiro, Brazil—died Oct. 2, 1987, London, Eng.) was a Brazilian-born British zoologist who received, with Sir Frank Macfarlane Burnet, the Nobel Prize for Physiology or Medicine in 1960 for developing and proving the theory of acquired immunological tolerance, a model that paved the way for successful organ and tissue transplantation.

Medawar was born in Brazil and moved to England as a young boy. In 1935 he took a degree in zoology from Magdalen College, Oxford, and in 1938 he became a fellow of the college. During World War II at the Burns Unit of the Glasgow Royal Infirmary in Scotland, he carried out research on tissue transplants, particularly skin grafting. That work led him to recognize that graft rejection is an immunological response. After the war, Medawar continued his transplant research and learned of the work done by Australian immunologist Frank Macfarlane Burnet, who first advanced the theory of acquired immunological tolerance. According to that hypothesis, during early embryological development and soon after birth, vertebrates develop the ability to distinguish between substances that belong to its body and those that are foreign. The idea contradicted the view that vertebrates inherit this ability at conception. Medawar lent support to Burnet’s theory when he found that fraternal cattle twins accept skin grafts from each other, indicating that certain substances known as antigens “leak” from the yolk sac of each embryo twin into the sac of the other. In a series of experiments on mice, he produced evidence indicating that, although each animal cell contains certain genetically determined antigens important to the immunity process, tolerance can also be acquired because the recipient injected as an embryo with the donor’s cells will accept tissue from all parts of the donor’s body and from the donor’s twin. Medawar’s work resulted in a shift of emphasis in the science of immunology from one that assumed a fully developed immune mechanism to one that attempts to alter the immune mechanism itself, as in the attempt to suppress the body’s rejection of organ transplants.

Medawar was professor of zoology at the University of Birmingham (1947–51) and University College, London (1951–62), director of the National Institute for Medical Research, London (1962–71), professor of experimental medicine at the Royal Institution (1977–83), and president of the Royal Postgraduate Medical School (1981–87). He was knighted in 1965 and awarded the Order of Merit in 1981.

Medawar’s works include The Uniqueness of the Individual (1957), The Future of Man (1959), The Art of the Soluble (1967), The Hope of Progress (1972), The Life Science (1977), Pluto’s Republic (1982), and his autobiography, Memoir of a Thinking Radish (1986).

Details

Sir Peter Brian Medawar (28 February 1915 – 2 October 1987) was a British biologist and writer, whose works on graft rejection and the discovery of acquired immune tolerance have been fundamental to the medical practice of tissue and organ transplants. For his scientific works, he is regarded as the "father of transplantation". He is remembered for his wit both in person and in popular writings. Richard Dawkins referred to him as "the wittiest of all scientific writers"; Stephen Jay Gould as "the cleverest man I have ever known".

Medawar was the youngest child of a Lebanese father and a British mother, and was both a Brazilian and British citizen by birth. He studied at Marlborough College and Magdalen College, Oxford, and was professor of zoology at the University of Birmingham and University College London. Until he was partially disabled by a cerebral infarction, he was Director of the National Institute for Medical Research at Mill Hill. With his doctoral student Leslie Brent and postdoctoral fellow Rupert E. Billingham, he demonstrated the principle of acquired immunological tolerance (the phenomenon of unresponsiveness of the immune system to certain molecules), which was theoretically predicted by Sir Frank Macfarlane Burnet. This became the foundation of tissue and organ transplantation. He and Burnet shared the 1960 Nobel Prize in Physiology or Medicine "for discovery of acquired immunological tolerance".

Early life and education

Medawar was born in Petrópolis, a town 40 miles north of Rio de Janeiro, Brazil, where his parents were living. He was the third child of Lebanese Nicholas Agnatius Medawar, born in the village of Jounieh, north of Beirut, Lebanon, and British mother Edith Muriel (née Dowling). He had a brother Philip and a sister Pamela. (Pamela was later married to Sir David Hunt, who served as Private Secretary to prime ministers Clement Attlee and Winston Churchill.) His father, a Maronite Catholic, became a naturalised British citizen and worked for a British dental supplies manufacturer that sent him to Brazil as an agent. He later described his father's profession as selling "false teeth in South America". His status as a British citizen was acquired at birth, as he said, "My birth was registered at the British Consulate in good time to acquire the status of 'natural-born British subject'."

Medawar left Brazil with his family for England at the end of World War I, in 1918 and he lived there for the rest of his life. According to other accounts, he moved to England when he was 13 (i.e., 1928–1929) or 14 (i.e., 1929–1930). Under Brazilian nationality law, he had Brazilian citizenship from having been born there (jus soli). When he turned 18, the age at which Brazilians are liable to conscription, he applied for exemption to Joaquim Pedro Salgado Filho, his godfather and the then Minister of Aviation. This was denied by President Eurico Gaspar Dutra, so Medawar renounced his Brazilian citizenship.

In 1928, Medawar went to Marlborough College in Marlborough, Wiltshire. He hated the college because "they were critical and querulous at the same time, wondering what kind of person a Lebanese was—something foreign you can be sure", and also because of its preference for sports, in which he was weak. An experience of bullying and racism made him feel the rest of his life "resentful and disgusted at the manners and mores of [Marlborough's] essentially tribal institution," and likened it to the training schools for the Nazi SS as all "founded upon the twin pillars of sex and sadism." His proudest moments at the college were with his teacher Ashley Gordon Lowndes, to whom he credited the beginning of his career in biology. He said Lowndes was "barely literate" but "a very, very good biology teacher". Lowndes had taught eminent biologists including John Z. Young and Richard Julius Pumphrey. Yet Medawar was inherently weak in dissection and was constantly irked by their dictum: "Bloody foolish is the boy whose drawing of his dissection differs in any way whatsoever from the diagram in the textbook."

In 1932, he went on to Magdalen College, Oxford, graduating with a first-class honours degree in zoology in 1935. Medawar was appointed Christopher Welch scholar and senior demy of Magdalen in 1935. He also worked at the Sir William Dunn School of Pathology supervised by Howard Florey (later Nobel laureate, and who inspired him to take up immunology) and completed his doctoral thesis in 1941. In 1938, he became Fellow of Magdalen through an examination, the position he held until 1944. It was there that he started working with J. Z. Young on the regeneration of nerves. His invention of a nerve glue proved useful in surgical operations of severed nerves during World War II.

The University of Oxford approved his Doctor of Philosophy thesis titled "Growth promoting and growth inhibiting factors in normal and abnormal development" in 1941, but because of the prohibitive cost of supplication (the process by which the degree is officially conferred), he spent the money on his urgent appendicectomy instead. The University of Oxford later awarded him a Doctor of Science degree in 1947.

Career and research

After completing his PhD, Medawar was appointed a Rolleston Prizeman in 1942, senior research fellow of St John's College, Oxford, in 1944, and a university demonstrator in zoology and comparative anatomy, also in 1944. He was re-elected fellow of Magdalen from 1946 to 1947. In 1947, he became Mason Professor of Zoology at the University of Birmingham and worked there until 1951. He transferred to University College London in 1951 as Jodrell Professor of Zoology and Comparative Anatomy.

In 1962, he was appointed director of the National Institute for Medical Research. His predecessor Sir Charles Harrington was an able administrator such that taking over his post was, as he described, "[N]o more strenuous than ... sliding over into the driving-seat of a Rolls-Royce". He was head of the transplantation section of the Medical Research Council's clinical research centre at Harrow from 1971 to 1986. He became professor of experimental medicine at the Royal Institution (1977–1983), and president of the Royal Postgraduate Medical School (1981–1987).

Jai Ganesh · Dark Discussions at Cafe Infinity

27) Girard Desargues

Girard Desargues (21 February 1591 – September 1661) was a French mathematician and engineer, who is considered one of the founders of projective geometry. Desargues' theorem, the Desargues graph, and the crater Desargues on the Moon are named in his honour.

Biography

Born in Lyon, Desargues came from a family devoted to service to the French crown. His father was a royal notary, an investigating commissioner of the Seneschal's court in Lyon (1574), the collector of the tithes on ecclesiastical revenues for the city of Lyon (1583) and for the diocese of Lyon.

Girard Desargues worked as an architect from 1645. Prior to that, he had worked as a tutor and may have served as an engineer and technical consultant in the entourage of Richelieu. Yet his involvement in the Siege of La Rochelle, though alleged by Ch. Weiss in Biographie Universelle (1842), has never been testified.

As an architect, Desargues planned several private and public buildings in Paris and Lyon. As an engineer, he designed a system for raising water that he installed near Paris. It was based on the use of the epicycloidal wheel, the principle of which was unrecognized at the time.

His research on perspective and geometrical projections can be seen as a culmination of centuries of scientific inquiry across the classical epoch in optics that stretched from al-Hasan Ibn al-Haytham (Alhazen) to Johannes Kepler, and going beyond a mere synthesis of these traditions with Renaissance perspective theories and practices.

His work was rediscovered and republished in 1864. A collection of his works was published in 1951, and the 1864 compilation remains in print. One notable work, often cited by others in mathematics, is "Rough draft for an essay on the results of taking plane sections of a cone" (1639).

Late in his life, Desargues published a paper with the cryptic title of DALG. The most common theory about what this stands for is Des Argues, Lyonnais, Géometre (proposed by Henri Brocard).

He died in Lyon.

Jai Ganesh · This is Cool

2482) Skeletal Muscle

Gist

Skeletal muscle is a type of muscle tissue attached to bones by tendons, responsible for voluntary movements like walking, lifting, and maintaining posture, and is characterized by its striped (striated) appearance and control by the nervous system for conscious action. It's a vital organ, making up a significant portion of body weight, and also generates heat, protects organs, and stores nutrients.

People with problems of skeletal muscle usually present with complaints of pain, stiffness or weakness. Muscle pain and pain caused by other structures in the body can be difficult to identify because muscle overlies many different types of structures including the bursa , joints, and bone.

Summary

Skeletal muscle, in vertebrates, is the most common of the three types of muscle in the body. Skeletal muscles are attached to bones by tendons, and they produce all the movements of body parts in relation to each other. Unlike smooth muscle and cardiac muscle, skeletal muscle is under voluntary control. Similar to cardiac muscle, however, skeletal muscle is striated; its long, thin, multinucleated fibres are crossed with a regular pattern of fine red and white lines, giving the muscle a distinctive appearance. Skeletal muscle fibres are bound together by connective tissue and communicate with nerves and blood vessels.

Details

Skeletal muscle (commonly referred to as muscle) is one of the three types of vertebrate muscle tissue, the others being cardiac muscle and smooth muscle. They are part of the voluntary muscular system and typically are attached by tendons to bones of a skeleton. The skeletal muscle cells are much longer than in the other types of muscle tissue, and are also known as muscle fibers. The tissue of a skeletal muscle is striated – having a striped appearance due to the arrangement of the sarcomeres.

A skeletal muscle contains multiple fascicles – bundles of muscle fibers. Each individual fiber and each muscle is surrounded by a type of connective tissue layer of fascia. Muscle fibers are formed from the fusion of developmental myoblasts in a process known as myogenesis resulting in long multinucleated cells. In these cells, the nuclei, termed myonuclei, are located along the inside of the cell membrane. Muscle fibers also have multiple mitochondria to meet energy needs.

Muscle fibers are in turn composed of myofibrils. The myofibrils are composed of actin and myosin filaments called myofilaments, repeated in units called sarcomeres, which are the basic functional, contractile units of the muscle fiber necessary for muscle contraction. Muscles are predominantly powered by the oxidation of fats and carbohydrates, but anaerobic chemical reactions are also used, particularly by fast twitch fibers. These chemical reactions produce adenosine triphosphate (ATP) molecules that are used to power the movement of the myosin heads.

Skeletal muscle comprises about 35% of the body of humans by weight. The functions of skeletal muscle include producing movement, maintaining body posture, controlling body temperature, and stabilizing joints. Skeletal muscle is also an endocrine organ. Under different physiological conditions, subsets of 654 different proteins as well as lipids, amino acids, metabolites and small RNAs are found in the secretome of skeletal muscles.

Skeletal muscles are substantially composed of multinucleated contractile muscle fibers (myocytes). However, considerable numbers of resident and infiltrating mononuclear cells are also present in skeletal muscles. In terms of volume, myocytes make up the great majority of skeletal muscle. Skeletal muscle myocytes are usually very large, being about 2–3 cm long and 100 μm in diameter. By comparison, the mononuclear cells in muscles are much smaller. Some of the mononuclear cells in muscles are endothelial cells (which are about 50–70 μm long, 10–30 μm wide and 0.1–10 μm thick), macrophages (21 μm in diameter) and neutrophils (12-15 μm in diameter). However, in terms of nuclei present in skeletal muscle, myocyte nuclei may be only half of the nuclei present, while nuclei from resident and infiltrating mononuclear cells make up the other half.

Additional Information

Skeletal muscles comprise 30% to 40% of your total body mass. They’re the muscles that connect to your bones and allow you to perform a wide range of movements and functions. Skeletal muscles are voluntary, meaning you control how and when they work. It’s important to keep your skeletal muscles as strong and healthy as possible.

Overview:

What is skeletal muscle?

The majority of the muscles in your body are skeletal muscles (striated muscles). They make up between 30% and 40% of your total body mass. Tendons (tough bands of connective tissue) attach skeletal muscle tissue to bones throughout your body. Your shoulder muscles, hamstring muscles and abdominal muscles are all examples of skeletal muscles.

There are three types of muscles in your body: skeletal, cardiac and smooth muscle. Skeletal muscles are voluntary muscles, meaning you control how and when they move and work. Nerves in your somatic nervous system send signals to make them function. If you reach for a book on a shelf, you’re using skeletal muscles in your neck, arm and shoulder.

Cardiac and smooth muscle are involuntary muscles that your autonomic nervous system controls. That means they work without you having to think about it. For example, muscles in your urinary system help rid your body of waste and toxins.

Skeletal muscle mass varies from person to person. Males have more skeletal muscle mass than females. People who are tall or have overweight also tend to have higher muscle mass. Muscle mass decreases with age.

Function:

What do skeletal muscles do?

Your striated muscles are a vital part of your musculoskeletal system. They serve a variety of functions, including:

* Chewing and swallowing, which are the first parts of digestion
* Expanding and contracting your chest cavity so you can inhale and exhale
* Maintaining body posture
* Moving the bones in different parts of your body
* Protecting your joints and holding them in place
* Storing nutrients
* Sustaining body temperature

Anatomy:

Where are the skeletal muscles located?

Your skeletal muscles are located between the bones (skeletal system) throughout your body. They consist of flexible muscle fibers that range from less than half an inch to just over 3 inches in diameter. These fibers usually span the length of the muscle. The fibers contract (tighten), which allows the muscles to move bones so you can perform lots of different movements.

What are the parts of skeletal muscles?

Each muscle can contain thousands of fibers. Different types of sheaths, or coverings, surround the fibers:

* Epimysium. The outermost layer of tissue surrounding the entire muscle.
* Perimysium. The middle layer surrounding bundles of muscle fibers.
* Endomysium. The innermost layer surrounding individual muscle fibers.

What do skeletal muscles look like?

Skeletal muscle fibers are red and white. They look striated, or striped, so they’re often called striated muscles. Cardiac muscles are also striated, but smooth muscles aren’t.

Conditions and Disorders:

What are the common conditions and disorders that affect striated muscles?

A wide range of conditions can affect skeletal muscles, from mild injuries to serious or even life-threatening myopathies (diseases that affect skeletal muscles). A few are:

* Muscular dystrophies
* Myasthenia gravis (MG)
* Rhabdomyolysis
* Sarcopenia
* Strains
* Tendonitis.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#10721. What does the term in Geography County mean?

#10722. What does the term in Geography Course mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#2555. What does the medical term Dental fluorosis mean?

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#5917. What does the noun designation mean?

#5918. What does the noun desperado mean?

Jai Ganesh · Dark Discussions at Cafe Infinity

Combat Quotes - I

1. Errors of opinion may be tolerated where reason is left free to combat it. - Thomas Jefferson

2. Virtue is a state of war, and to live in it we have always to combat with ourselves. - Jean-Jacques Rousseau

3. There should be an honest attempt at the reconciliation of differences before resorting to combat. - Jimmy Carter

4. In the re-creation of combat situations, and this is coming from a director who's never been in one, being mindful of what these veterans have actually gone through, you find that the biggest concern is that you don't look at war as a geopolitical endeavor. - Steven Spielberg

5. I think I'd be a better president because I was in combat. - George H. W. Bush

6. I exhort you also to take part in the great combat, which is the combat of life, and greater than every other earthly conflict. - Plato

7. One thing that was amazing about World War II was that everybody signed up for the duration plus six months. Fliers got to leave combat after 25 missions, or 35 missions, but other than that, you were in it. You were part of the great effort, until, oh boy, six months after it was over. - Tom Hanks

8. I've led a life of such structured discipline and always had a goal in mind of knowing what I was doing, from West Point to the Air Force combat, MIT, looking for new things to study and get involved in. And then I got into the space program, and how disciplined can you get? - Buzz Aldrin.

Jai Ganesh · Jokes

Q: Why does the jellybean go to school?
A: Because he wants to become a smartie.
* * *
Q: What do you get when you cross Ice, chocolate, a big strawberry, a giant pineapple, and cold milk?
A: The world's best Sundae!
* * *
Q: How many grams of protein are there in that slice of chocolate pie?
A: 3.14159265...
* * *
Q: What do you call people who like to drink hot chocolate all year long?
A: Cocoa-Nuts.
* * *
Life is like a box of chocolates, It doesn't last too long for fat people.
* * *

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#9840.

Jai Ganesh · Jai Ganesh's Puzzles

Hi,

#6334.

Jai Ganesh · Exercises

Hi,

2691.

Jai Ganesh · This is Cool

Madagascar

Gist

Madagascar, an island nation off Africa's southeastern coast in the Indian Ocean, is the world's fourth-largest island, renowned for its incredible biodiversity, with over 90% of its wildlife—including lemurs—found nowhere else on Earth. Known for baobabs and unique landscapes, its capital is Antananarivo, and it features a blend of Malagasy, African, and Asian cultural influences.

Madagascar is known for its extraordinary biodiversity, especially its unique wildlife like lemurs and chameleons, found nowhere else, alongside unique landscapes such as the Avenue of the Baobabs, tropical rainforests, and spiny deserts, making it a biodiversity hotspot and a top destination for nature lovers seeking adventure. Its rich culture blends Indonesian and African influences, while it's also famous for vanilla and pepper production.

Summary

Details

Madagascar is an island country lying off the southeastern coast of Africa. Madagascar is the fourth largest island in the world, after Greenland, New Guinea, and Borneo.

Although located some 250 miles (400 km) from the African continent, Madagascar’s population is primarily related not to African peoples but rather to those of Indonesia, more than 3,000 miles (4,800 km) to the east. The Malagasy peoples, moreover, do not consider themselves to be Africans, but, because of the continuing bond with France that resulted from former colonial rule, the island developed political, economic, and cultural links with the French-speaking countries of western Africa. The animal life and vegetation of the island are equally anomalous, differing greatly from that of nearby Africa and being in many respects unique. Although the coastlands have been known to Europeans for more than 400 years and to Arabs for much longer, recent historical development has been more intense and concentrated in the central plateau, which contains the capital city of Antananarivo (formerly Tananarive).

Land

Madagascar is located in the southwestern Indian Ocean and is separated from the African coast by the 250-mile- (400-km-) wide Mozambique Channel.

Relief

Madagascar consists of three parallel longitudinal zones—the central plateau, the coastal strip in the east, and the zone of low plateaus and plains in the west.

Situated between 2,500 and 4,500 feet (800 and 1,400 metres) above sea level, the plateau has been uplifted and worn down several times and is tilted to the west. Three massifs are more than 8,500 feet (2,600 metres) high. The Tsaratanana region in the north is separated from the rest of the plateau by the Tsaratanana Massif, whose summit, Maromokotro, reaches 9,436 feet (2,876 metres) and is the highest point on the island. Ankaratra Massif in the centre is an enormous volcanic mass whose summit, Tsiafajavona, is 8,671 feet (2,643 metres) high. Ankaratra is a major watershed divide separating three main river basins. Farther south, Andringitra is a vast granite massif north of Tôlan̈aro (Faradofay); it rises to 8,720 feet (2,658 metres) at Boby Peak.

The plateau slopes with some regularity toward the extreme southern plain, but its boundaries to the east and west are more abrupt. To the east it descends in a sharp fault, by vertical steps of 1,000 to 2,000 feet (300 to 600 metres). This cliff, which is called the Great Cliff or the Cliff of Angavo, is often impassable and is itself bordered by the Betsimisaraka Escarpment, a second and lower cliff to the east, which overhangs the coastal plain. Behind the scarp face are the remains of ancient lakes, including one called Alaotra. To the south the two steep gradients meet and form the Mahafaly and the Androy plateaus, which overhang the sea in precipitous cliffs. Toward the west the descent is made in a series of steps. However, in places the central plateau is bordered by an impassable escarpment, such as the Cliff of Bongolava in the west-central part of the island. To the extreme north the plateau is bordered by the low belt of the Ambohitra Mountains, which include a series of volcanic craters.

The coastal strip has an average width of about 30 miles (50 km). It is a narrow alluvial plain that terminates in a low coastline bordered with lagoons linked together by the Pangalanes (Ampangalana) Canal, which is more than 370 miles (600 km) long. To the south of Farafangana the coast becomes rocky, and in the southeast there occur many little bays. To the northeast is the deep Bay of Antongil (Antongila).

The western zone is between 60 and 125 miles (100 and 200 km) wide. Its sedimentary layers slope toward the Mozambique Channel and produce a succession of hills. The inland (eastern) side of these steep hills dominates the hollows formed in the soft sediments of the interior, while the other side descends to the sea in rocky slopes. The coastline is straight, bordered by small dunes and fringed with mangroves. The currents in the Mozambique Channel have favoured the offshore deposit of alluvium and the growth of river deltas. On the northwestern coast there are a number of estuaries and bays. This coast is bordered by coral reefs and volcanic islands, such as Nosy Be (Nossi-Bé), which protects Ampasindava Bay.

Drainage

The steep eastern face of the plateau is drained by numerous short, torrential rivers, such as the Mandrare, the Mananara, the Faraony, the Ivondro, and the Maningory, which discharge either into the coastal lagoons or directly into the sea over waterfalls and rapids. The more gently sloping western side of the plateau is crossed by longer and larger rivers, including the Onilahy, the Mangoky, the Tsiribihina, and the Betsiboka, which bring huge deposits of fertile alluvium down into the vast plains and many-channeled estuaries; the river mouths, while not completely blocked by this sediment, are studded with numerous sandbanks.

There are many lakes of volcanic origin on the island, such as Lake Itasy. Alaotra is the last surviving lake of the eastern slope. Lake Tsimanampetsotsa, near the coast south of Toliara (formerly Tuléar), is a large body of saline water that has no outlet.

Soils

The central plateau and the eastern coast are mainly composed of gneiss, granite, quartz, and other crystalline rock formations. The gneiss decomposes into red murrum, laterite, and deeper and more fertile red earths, giving Madagascar its colloquial name the Great Red Island. Fertile alluvial soils in the valleys support intensive cultivation. There also are scattered volcanic intrusions that produce fertile but easily erodible soils. Lake Alaotra is a large sedimentary pocket in the central plateau containing some of the island’s most productive farmland. The western third of the island consists entirely of deposits of sedimentary rock, giving rise to soils of medium to low fertility.

Climate of Madagascar

The hot, wet season extends from November to April and the cooler, drier season from May to October. The climate is governed by the combined effects of the moisture-bearing southeast trade and northwest monsoon winds as they blow across the central plateau. The trade winds, which blow throughout the year, are strongest from May to October. The east coast is to the windward and has a high annual rate of precipitation, reaching nearly 150 inches (3,800 mm) at Maroantsetra on the Bay of Antongil. As the winds cross the plateau, they lose much of their humidity, causing only drizzle and mists on the plateau itself and leaving the west in a dry rain shadow. The southwest in particular is almost desert, with the dryness aggravated by a cold offshore current.

The monsoon, bringing rain to the northwest coast of Madagascar and the plateau, is most noticeable during the hot, humid season. The wind blows obliquely onto the west coast, which receives a moderate amount of precipitation annually; the southwest, which is protected, remains arid. Annual precipitation drops from about 80 inches (about 2,000 mm) on the northwestern island of Nosy Be to about 40 inches (1,000 mm) at Maintirano on the west coast to about 14 inches (360 mm) at Toliara in the southwest. The plateau receives moderate levels of precipitation, with about 50 inches (1,200 mm) falling annually at both Antananarivo and Fianarantsoa, which lies about 200 miles (320 km) farther south.

July is the coolest month, with mean monthly temperatures around the island ranging from the low 50s F (low 10s C) to the high 70s F (mid-20s C), and December is the hottest month, with temperatures between the low 60s and mid-80s F (mid 10s and high 20s C). Temperatures generally decrease with elevation, being highest on the northwest coast and lowest on the plateau.

Tropical cyclones are an important climatic feature. They form far out over the Indian Ocean, especially from December to March, and approach the eastern coast, bringing torrential rains and destructive floods.

Plant and animal life

Much of the island was once covered with evergreen and deciduous forest, but little now remains except on the eastern escarpment and in scattered pockets in the west. The plateau is particularly denuded and suffers seriously from erosion. The forest has been cut in order to clear rice fields, to obtain fuel and building materials, and to export valuable timber such as ebony, rosewood, and sandalwood. About seven-eighths of the island is covered with prairie grasses and bamboo or small thin trees. There also are screw pines, palms, and reeds on the coasts. In the arid south of the island grow thorn trees, giant cacti, dwarf baobab trees, pachypodium succulents, and other xerophytes (drought-resistant plants) that are peculiar to the island.

Because of the island’s isolation, many zoologically primitive primates have survived and evolved into unique forms. About 40 species of lemurs are indigenous to Madagascar. Several unique hedgehoglike insectivores, such as the tenrec, have evolved there, and there are also many kinds of chameleons of varying size. Birds are numerous and include guinea fowl, partridges, pigeons, herons, ibis, flamingos, egrets, cuckoos, Asian robins, and several kinds of birds of prey. There are about 800 species of butterflies, many moths, and a variety of spiders. The only large or dangerous animals are the crocodiles, which occupy the rivers. The snakes, including the do, which is 10 to 13 feet (3 to 4 metres) in length, are harmless.

Inland waters contain tilapia (an edible perchlike fish), rainbow trout, and black bass. Marine fish and crustaceans abound on the coasts and in the lagoons, estuaries, and even in some upland streams. They include groupers, giltheads, tuna, sharks, sardines, whitings, crayfish, crabs, shrimps, mussels, and oysters. The coelacanth, referred to as a living fossil and once thought extinct for millions of years, inhabits offshore waters.

Additional Information

Located off the east coast of Africa in the Southwest Indian Ocean, Madagascar is the world’s fourth largest island; at 146 million acres, it’s almost the size of Texas. Madagascar’s climate is tropical along the coast, temperate inland, and arid in the south. The island harbors lush rain forests, tropical dry forests, plateaus, and deserts. Its more than 3,000 miles of coastline and over 250 islands are home to some of the world’s largest coral reef systems, tidal marshes, seagrass beds, and most extensive mangrove areas in the Western Indian Ocean.

More than 11,000 endemic plant species, including seven species of baobab tree and all lemur species, share Madagascar with a vast variety of mammals, reptiles, fish, amphibians, and birds. Along the Northern Mozambique Channel, in the northwest, is Nosy Hara National Park, a world hotspot of marine diversity where an incredible 265 species of corals can be found. The country’s interior has several critically threatened species including the smallest chameleon in the world, Brookesia micra, and Verreaux’s sifaka, a lemur found in the southwest forests.

People and communities of Madagascar

Madagascar has a population of more than 21 million people with a wide array of faiths and customs, more than 20 ethnic groups coexist on the island. A majority of the population—70 percent of which is estimated to live below the international poverty line—depends completely on natural resources via subsistence farming and fishing. The ocean surrounding Madagascar has long been an important resource for coastal populations. 1.5 million people depend on fishing for their livelihoods and marine ecotourism is a growing sector of the national economy. Well over half of fishers are women and women are the primary cleaners, processors, and sellers of marine products.

Climate change

Climate change is causing increased and more severe drought in the south and more intense cyclones and flooding in the middle and north regions of Madagascar. This extreme weather forces millions of people to migrate across the country and puts added pressure on resources, including forests and fisheries. Warming oceans due to climate change is also leading to mass mortality in coral reefs.

Deforestation

The small-scale but widespread clearance of inland forest and coastal mangroves, primarily for firewood and charcoal production, is jeopardizing the island’s habitats and species such as lemurs and chameleons. Deforestation increases sediment flow out to the ocean and can smother coral reefs and reduce the productivity of fisheries.

Climate change has also increased the severity of droughts. Droughts are causing a surge in migration towards the country’s coastal areas and people are transitioning from agriculture to fishing, putting additional pressure on coastal environments and increasing demand for mangrove charcoal and timber. Over 12,000 acres of mangroves have been lost since 1996.

Governance and security

Only 3.1% of marine areas are formally protected in Madagascar and limited staff capacity and resources to manage and create marine protected areas hinder effective legislation. Management issues can impact distribution of industrial fisheries licenses and fish trader permits while inadequate monitoring, control, surveillance, and enforcement can exacerbate overfishing and illegal fishing.

The complicated history of Madagascar and its legal system contributes to significant policy variations across the country, complicating integration across economic sectors and with the broader Southwest Africa region to address cross-cutting policy and governance issues.

Unsustainable Fishing

It is estimated that some 130,000 tons of fish are illegally fished from Madagascar’s marine territories every year, amounting to a loss of $142.8 million in potential income. Bottom trawling and seine netting degrade and damage coral reefs, threatening the long-term resource availability and food security for coastal communities. As reefs degrade, fishers are forced to find different, less exploited reefs and may repeat the same damaging practices. Under weak governance and rising insecurity, unsustainable fishing practices thrive and threaten coastal livelihoods and food security. Illegal, unreported, and unregulated fishing is a pervasive problem and contributes to overfishing.

Math Is Fun Forum

#1 This is Cool » Time Zone » Yesterday 21:56:39

#2 Re: This is Cool » Miscellany » Yesterday 18:28:25

#3 Re: Dark Discussions at Cafe Infinity » crème de la crème » Yesterday 18:06:46

#4 This is Cool » Civet » Yesterday 17:41:38

#5 Science HQ » Sternum » Yesterday 17:10:37

#6 Dark Discussions at Cafe Infinity » Combat Quotes - II » Yesterday 16:09:46

#7 Jokes » Coconut Jokes - I » Yesterday 15:41:00

#8 Re: Jai Ganesh's Puzzles » General Quiz » Yesterday 15:27:06

#9 Re: Jai Ganesh's Puzzles » Doc, Doc! » Yesterday 15:15:34

#10 Re: Jai Ganesh's Puzzles » English language puzzles » Yesterday 15:07:03

#11 Re: Jai Ganesh's Puzzles » 10 second questions » Yesterday 14:26:14

#12 Re: Jai Ganesh's Puzzles » Oral puzzles » Yesterday 14:17:43

#13 Re: Exercises » Compute the solution: » Yesterday 14:06:51

#14 Re: Dark Discussions at Cafe Infinity » crème de la crème » 2026-01-31 20:14:08

#15 Re: Dark Discussions at Cafe Infinity » Greatest Mathematicians from 1 CE ... » 2026-01-31 19:38:27

#16 Re: This is Cool » Miscellany » 2026-01-31 19:04:04

#17 Re: Jai Ganesh's Puzzles » General Quiz » 2026-01-31 18:24:04

#18 Re: Jai Ganesh's Puzzles » Doc, Doc! » 2026-01-31 18:10:10

#19 Re: Jai Ganesh's Puzzles » English language puzzles » 2026-01-31 17:57:32

#20 Dark Discussions at Cafe Infinity » Combat Quotes - I » 2026-01-31 17:42:36

#21 Jokes » Chocolate Jokes - V » 2026-01-31 17:18:12

#22 Re: Jai Ganesh's Puzzles » 10 second questions » 2026-01-31 17:05:46

#23 Re: Jai Ganesh's Puzzles » Oral puzzles » 2026-01-31 16:50:42

#24 Re: Exercises » Compute the solution: » 2026-01-31 16:40:21

#25 This is Cool » Madagascar » 2026-01-31 16:22:03

Board footer