title: Aero L-39 Albatros

text: Iraq became the first export customer for the L-39 Albatros. By mid 1970, the Iraqi Air Force had procured a considerable number of L-39 trainers, having transferred the bulk of their training activities onto the Czechoslovak aircraft. During the American-led invasion of Iraq in 2003, on 14 April 2003, a pair of United States Navy McDonnell Douglas F/A-18 Hornets attacked several L-29 and L-39 aircraft on the ground at an airfield near the city of Tikrit; these had been believed to have been modified to perform as delivery platforms for weapons.


title: Aero L-39 Albatros

text: Libya acquired some 180 L-39ZOs around 1978 which served at Sabha and Okba Ben Nafi flying schools along with Yugoslav-made G-2 Galeb for advanced jet training and Italian-made SF.260s (for primary training).


title: Aero L-39 Albatros

text: The L-39s were deployed during the Chadian-Libyan conflict, mainly to Ouadi Doum air base. During the final Chadian offensive in March 1987, the Chadians captured Ouadi Doum along with several aircraft (11 L-39s included) and Soviet SAM systems and tanks. A Chadian report to the UN, reported the aforementioned capture on 11 L-39s and the destruction (or downing) of at least four of them.


title: Aero L-39 Albatros

text: In the midst of that conflict, on 21 April 1983, three LARAF Ilyushin Il-76TDs and one Lockheed C-130 Hercules landed at Manaus Airport, Brazil after one of the Il-76s developed technical problems while crossing the Atlantic Ocean. The aircraft were then searched by the Brazilian authorities: instead of medical supplies – as quoted in the transport documentation – the crate of the first of 17 L-39s bound for Nicaragua together with arms and parachutes, to support the country's war against US-backed Contras, were found. The cargo was impounded for some time before being returned to Libya, while the transports were permitted to return to their country. During the 1990s and 2000s, Libya made multiple attempts to get components and services for its air force in spite of an embargo placed upon the country by United Nations Security Council Resolution 748; by 2001, only half of Libya's L-39s were serviceable as a consequence.


title: Aero L-39 Albatros

text: Following the dissolution of the Soviet Union and the formation of the Russian Air Force in 1991, the newly formed service found itself with hundreds of L-39 aircraft, the majority of which were surplus to their training requirements. According to author Stephan Wilkinson, by 2005, Russia was seeking to potentially sell up to 800 of their L-39s, which were receiving only a basic level of maintenance once per month while their fate was being decided. Starting in the early 1990s, the Russian Air Force has pursued the development of a domestically-built jet trainer, for which the Yakovlev Yak-130 was selected; the Yak-130 shall eventually replace the L-39 in Russian service within its operational roles.


title: Aero L-39 Albatros

text: The Syrian Arab Air Force has operated a number of armed L-39ZA light attack variants. Since the early stages of the Syrian civil war, the Syrian Air Force's L-39 aircraft have been routinely deployed in counter-insurgency operations against various rebel ground forces, a number of these aircraft have also been shot down by ground fire. They were first used operationally during the Battle of Aleppo, launching several strikes upon rebel-held positions. It has been claimed the L-39 was the first fixed-wing aircraft to be employed against the rebels.


title: Aero L-39 Albatros

text: In February 2013, insurgents successfully captured a number of intact L-39s, along with their support equipment, after raiding and later taking over the Al-Jarrah airbase. In late 2013, reports emerged of claims by Islamist fighters that they had successfully flown two of the captured L-39s. In October 2014, the Syrian Government claimed that at least two rebel-held L-39s had been airworthy and had recently been destroyed by Syrian Air Force aircraft.


title: Aero L-39 Albatros

text: According to Reuters, by 2014, the L-39 had allegedly become one of the favoured platforms of the Syrian Air Force for performing ground attack missions due to its slower speed and higher agility over other aircraft in its inventory. In December 2015, following the securing of the Kweiris airbase by government forces, the resumption of ground-attack missions by L-39s in the vicinity of Aleppo commenced shortly thereafter.


title: Aero L-39 Albatros

text: On 3 March 2020, a Syrian Arab Army Air Force L-39 was shot down by a Turkish Air Force F-16 over Idlib province. Both Syrian and Turkish forces confirmed the downing.


title: Aero L-39 Albatros

text: While newer versions are now replacing older L-39s in service, thousands remain in active service as trainers, and many are finding new homes with private warbird owners all over the world. It has been claimed that the L-39's desirability stems from the fact that it is "the only available second-generation jet trainer". This trend is particularly evident in the United States, where their $200,000–$300,000 price puts them in range of moderately wealthy pilots looking for a fast, agile personal jet. Their popularity led to a purely L-39 Jet class being introduced at the Reno Air Races in 2002, though it has since been expanded to include other, similar aircraft.


title: Aero L-39 Albatros

text: In September 2012, there were 255 L-39s registered with the U.S. Federal Aviation Administration and four registered with Transport Canada. Several display teams use the L-39 such as the Patriots Jet Team (6 L-39s), the Breitling Jet Team (7 L-39s) and the Black Diamond Jet Team (5 L-39s). There are also several L-39s that have been made available for private jet rides by various operators in Australia, Czech Republic, France, Germany, Spain and the USA. These L-39s are mostly in private hands, but some also belong to government agencies, such as those in Vyazma, Russia. In March 2018 there were five L-39s on the civilian register in New Zealand. One registered as an L-39 and four others registered as L-39C


title: Aero L-39 Albatros

text: Since 2004, the Defence & MRO Division of Aero Vodochody has performed a general maintenance, repair and modernisation program of civil-operated L-39s, as well as performing the demilitarisation of ex-military aircraft. Services offered to civil operators include life-extension programs, support for civil registration/certification, training of ground/flight crew, logistics and analysis, customization, routine inspection, condition-based maintenance support, and providing general expertise/consultancy work.


title: Balut (food)

text: Balut ( , ; also spelled as balot) is a fertilized developing egg embryo that is boiled or steamed and eaten from the shell. It is commonly sold as street food in South China and Southeast Asian countries, notably the Philippines, Cambodia (, ) and Vietnam (). The term comes from the Filipino language.


title: Balut (food)

text: The length of incubation before the egg is cooked is a matter of local preference, but generally ranges between 14 and 21 days.


title: Balut (food)

text: A balut is a fertilized bird egg (usually a duck) which is incubated for a period of 30 to 53 days, depending on the local culture, and then steamed. The contents are eaten directly from the shell. Balut that is incubated for longer periods have a well-developed embryo and the features of the duckling are recognizable. The partially-developed embryo bones are soft enough to chew and swallow as a whole. The mallard duck ("Anas platyrhynchus"), also known as the "Pateros duck", is often used to make balut.


title: Balut (food)

text: Balut is common street food in the Philippines and other localities, and is also sold in stores and malls. It is a relatively cheap source of protein and calcium. Balut was introduced to the Philippines by the Chinese in 1565 or around 1885 and since then, balut has been included as a traditional part of the culture. Wherever Filipinos migrated for work, a large market for balut would develop. Controversies arose as knowledge of the food spread around the Southeast Asian countries and then globally. People questioned the ethics of eating balut.


title: Balut (food)

text: Traditionally, the fertilized eggs are incubated in the sun or buried in sand, and stored in baskets to retain warmth. In order for the embryo to develop normally, it must be exposed to heat for the correct period of time, while ensuring that the temperature is not too hot to harm the eggs or too cold to permit growth. The embryo is very sensitive to high temperatures, and is easily killed upon cooking in the sun. After nine days, the eggs are held to a light, in a process called candling, to reveal the embryo inside. The production of balut depends on egg maturation cycles, where the egg begins developing and changes in texture. Throughout these various maturation periods, different temperatures are required to accentuate the specific egg and embryo characteristics. Within the first few stages of maturation, balut is known as "balut sa puti" ("wrapped in white") when it is white; the embryo inside is insufficiently developed to show a beak, feathers or claws, and the bones are undeveloped. These are made from very specific egg types, less than five days old and with no visible surface cracks.


title: Balut (food)

text: The duration of egg incubation is a matter of local preference. In the Philippines, balut is generally incubated for 14 to 18 days before being boiled for consumption. At about 14 to 16 days of incubation, the embryo floats on top of the egg white and yolk, and the balut is called "mamatong". For most balut makers, the ideal incubation is said to be 17 days old.


title: Balut (food)

text: There are other versions of balut. In the Cambodian version, "pong tea khon", the egg is incubated for 18 to 20 days. In the Vietnamese version, "trứng vịt lộn", the egg is incubated for 19 to 21 days, when the embryo is old enough to be recognizable as a baby duck and has bones that will be firm but tender when cooked. Some men prefer to eat an embryo that is much more developed, "...so that it looks gross, because that is a way to prove your manhood."


title: Balut (food)

text: During the cooking process, changes occur in the food chemistry of balut, such as the sol dispersion of water molecules within the embryonic fluid. This liquid becomes the broth for the solid which are parts of the duck within the egg. Although balut mainly consists of protein, fat is present and is emulsified within the fertilized embryo. After cooking, it can be considered a protein gel (depending on the length of time it was cooked). Heating high-protein food such as balut can cause the chemical changes to take place and fully or partially denature proteins, causing the surface to become thick and causing an irreversible gel protein to form.


title: Balut (food)

text: Temperature has a significant impact on the final taste and texture of the cooked balut. Warm temperatures of change the taste and texture of the yolk by making it more grainy. This can be attributed to the changes in proteins, and their partial denaturation, during the heating and incubation process. When boiling or cooking eggs, the white of the egg tends to solidify because the proteins are denatured in an irreversible reaction and turn from transparent to an opaque white. Physical and chemical changes in the final balut product can also be attributed to microbial infections and the rate that microbes infect the balut at various stages.


title: Balut (food)

text: There are many chemical changes that occur inside the duck egg as it is being processed, which can vary depending on how or what it is cooked with. While boiling, added salt can contribute to a number of chemical changes; it seems to increase the proportional weight of egg white within the shell, which can be due to the weight differences between the embryo and the egg white itself. Added salt can also increase the hardness of the egg yolk and affect the overall texture of the final balut product. Other chemical changes observed in nutrient content of the duck egg as it is processed are a slight decrease in the amount of available amino acids, water-soluble vitamins and minerals after the processing is complete.


title: Balut (food)

text: The Balut nutrition specifications between chicken and duck have minor differences, but both eggs have around 14 grams of crude protein, 188 calories each, and around 100 milligrams of calcium. A duck egg might have a higher value of nutrition than a chicken egg but overall, both chicken and duck balut have approximately the same nutritional value.


title: Balut (food)

text: In folk medicine, according to popular Vietnamese belief, these eggs are a nutritious and restorative food for pregnant or delivering women.


title: Balut (food)

text: Balut eggs are savored for their balance of textures and flavors. The broth surrounding the embryo is sipped from the egg before the shell is peeled, and the yolk and young chick inside can be eaten. All of the contents of the egg may be consumed, although the white albumen may remain uneaten depending on the age of the fertilized egg. This white albumen may have an unappetizing cartilaginous taste and is tough and rubbery in texture.


title: Balut (food)

text: In the Philippines, balut have recently entered "haute cuisine" by being served as appetizers in restaurants, cooked adobo style, fried in omelettes, or even used as filling in baked pastries. In Vietnam, balut is eaten with a pinch of pepper salt with lime/kumquat or ginger and rau răm (also known as laksa leaf). In Cambodia, balut is eaten while still warm in the shell and served with nothing more than a little garnish, which is usually a mixture of lime juice and ground pepper.


title: Balut (food)

text: A similar preparation is known in China as "maodan" (), "modan" (), "wangjidan" () or "huozhuzi" (). Chinese traders and migrants are said to have brought the idea of eating fertilized duck eggs to the Philippines. However, the knowledge and craft of balut-making has been localized by the balut-makers ("magbabalut"). Today, balut production has not been mechanized in favor of the traditional production by hand.


title: Balut (food)

text: Vendors sell cooked balut from buckets of sand (used to retain warmth) accompanied by small packets of salt. Uncooked balut are rarely sold in Southeast Asia. In the United States, Asian markets occasionally carry uncooked balut eggs. Alternatively, they can be ordered by mail. The cooking process is identical to that of hard-boiled chicken eggs, and baluts are eaten while still warm.


title: Balut (food)

text: Duck eggs that are not properly developed after nine to twelve days are sold as "penoy", which look, smell and taste similar to a regular hard-boiled egg. In Filipino cuisine, these are occasionally beaten and fried, similar to scrambled eggs, and served with a vinegar dip.


title: Balut (food)

text: Balut is consumed in high amounts within countries in Southeast Asia, including Laos, Cambodia, Vietnam, Thailand, and the Philippines. Pateros is a first-class municipality in Metro Manila, Philippines that is famous for its duck-raising industry and balut production. The Pateros municipality was actually named for its duck farmers by speakers of Spanish.


title: Balut (food)

text: Balut is recognized as a national food of the Philippines. It is commonly sold as a street food and served as an appetizer in restaurants. The taste of balut is similar to chicken soup. It has an unusual texture.


title: Balut (food)

text: Balut is found in some countries and locations of North America. While it cannot be found in every store in North America, specialty stores such as T&T, and, in particular, Filipino stores in the Greater Vancouver area, often sell balut. In the United States, growers such as Metzer Farms specialize in balut production, spreading the knowledge of balut and its awareness.


title: Balut (food)

text: A reason it may not be found or consumed as frequently in North America is that the majority of people outside of Southeast Asia still recognize balut as a novel and taboo food and often are anxious about trying it.


title: Balut (food)

text: In the Philippines, balut is often eaten with salt or a chili, garlic and vinegar (white or coconut sap) mixture to season, depending on personal preference. Balut can be served in many ways and may be cooked, boiled, and fried. It may be cooked adobo-style, fried in omelets, and used as filling in pastries. Although balut is globally recognized as a Filipino food, it is being consumed less and less in the Philippines. This is partly due to increasingly Western tastes, but also because balut is often associated with poverty.


title: Balut (food)

text: Some countries and locations will serve balut raw, although this is not a common practice. "Raw," in this sense, could mean the balut was lightly boiled or cooked very briefly. This is potentially dangerous since it increases the risk of spoiling and of ingesting harmful microorganisms.


title: Balut (food)

text: In Saigon, Vietnam, balut can be found in the streets where vendors operate on the back of motorbikes in alleys. Balut is served as quail eggs. First it is steamed and then served with salt, chili and pepper.


title: Balut (food)

text: Balut is considered to be a street food, and as with many street foods, balut should be eaten as soon as it is prepared. Sources suggest that at most, the shelf-life of a cooked balut is one day, but can be kept in the refrigerator for up to one week.


title: Balut (food)

text: According to the FDA Food Code, balut can perish over time or due to temperature changes. After being cooked, balut should be handled either at and above, or kept at or below .


title: Balut (food)

text: While most countries have specific regulations and standards for food, Canada has certain egg regulations pertaining to what products can be labelled as an egg. Balut eggs are not subjected to the egg regulations in Canada under the Canadian Food Inspection Agency, meaning they do not require the specific labeling requirements and rules of the traditional chicken egg.


title: Balut (food)

text: Eating balut is forbidden for some religious groups. Both Judaism and Islam have strict prohibitions on consuming food that is prepared in manners incompatible with religiously prescribed dietary laws. In Judaism, the embryo of a chick inside an egg of a bird, even a kosher bird, is forbidden for consumption. The Quran forbids consumption of meat if the animal has not been slaughtered properly, making the animal or animal-product "maytah". Because balut is an egg containing a partly-developed embryo, this makes it "haram", or "forbidden".


title: Balut (food)

text: In Christianity, the Members Church of God International forbids their members to eat "balut" for it is written in Acts 15:20, "But that we write unto them, that they abstain from pollutions of idols, and "from" fornication, and "from" things strangled, and "from" blood." According to them, the word "strangled" refers to those animals who died without pouring their blood upon the ground as written in Deut. 15:23. "Only thou shalt not eat the blood thereof; thou shalt pour it upon the ground as water."


title: Balut (food)

text: Information relating to whether boiling a partially-developed embryo is ethically acceptable or not can be found in the legislation relating to the euthanasia and treatment of research animals. Bird embryos that have reached greater than 50% of their incubation have developed a neural tube sufficient for pain perception; therefore, they should be euthanized by similar methods used in avian neonates such as anesthetic overdose, decapitation, or prolonged exposure to carbon dioxide. Similarly, in the UK, embryonic birds are "protected animals" once they have reached the last third of their incubation period. There are specified methods of humanely killing protected animals used in research, but boiling is not one of these. Depending on the species of duck, some eggs used for balut would be boiled within the last half or third of embryo development. Duck embryos are often taken off incubation in order to stunt the growth process; the embryos no longer develop, and become readily available for purchasing. The RSPCA Australia recommends against boiling the duck embryo from the 18th day of incubation onwards due to the potential for suffering beyond that point, and notes that it is "an area that is yet to be further researched".


title: Balut (food)

text: Several groups wish to ban balut. A petition has been raised to get 5,000 signatures to have balut labeled "fertilized duck egg with embryo" and taken off the menu in the Maharlika restaurant, New York. , the restaurant was selling balut for $5 each. As a response to this petition, Filipino New Yorkers have created a counter petition asking to leave the food item alone.


title: Balut (food)

text: The incubation temperatures and environment required for the proper development of balut during processing are ideal growth conditions for many bacteria including "Salmonella enteritidis". In addition, faecal pathogens can be deposited on the egg shell surface during laying. Balut is therefore labelled as a "Hazardous Food" in Canada. Warnings have been published to obtain balut only from safe, well-known producers.


title: Balut (food)

text: Outside of Southeast Asia, balut has been featured on reality television shows, such as in season 1 of "Bizarre Foods with Andrew Zimmern", or as part of eating challenges, such as on "Fear Factor" in 2002, "Hell's Kitchen" in 2013, "The Amazing Race Asia 2", "The Amazing Race Australia 2", "The Amazing Race Ukraine", "", "", "", and "".


title: Balut (food)

text: In the United States, eggs are sold at Asian markets. However, to get the right age eggs and to ensure freshness, it is recommended that they be purchased from a professional or an egg vendor at Asian farmers markets.


title: Balut (food)

text: On April 10, 2015, former Pateros mayor Jaime C. Medina collaborated with Center for Culinary Arts (CCA, Manila) and the History Channel to attempt to set the record for the world's largest serving of balut. The CCA chefs, headed by Tristan Encarnacion, prepared 1,000 pieces of balut into an adobo dish that was recorded to have weighed 117.5 kilograms. The resulting dish was enjoyed by the townsfolk in a symbolic boodle fight, with tables topped with banana leaves stretching along B. Morcilla Street.


title: Abacus

text: The abacus ("plural" abaci or abacuses), also called a counting frame, is a calculating tool which has been used since ancient times. It was used in the ancient Near East, Europe, China, and Russia, centuries before the adoption of the Hindu-Arabic numeral system. The exact origin of the abacus has not yet emerged. It consists of rows of movable beads, or similar objects, strung on a wire. They represent digits. One of the two numbers is set up, and the beads are manipulated to perform an operation such as addition, or even a square or cubic root.


title: Abacus

text: In their earliest designs, the rows of beads could be loose on a flat surface or sliding in grooves. Later the beads were made to slide on rods and built into a frame, allowing faster manipulation. Abacuses are still made, often as a bamboo frame with beads sliding on wires. In the ancient world, particularly before the introduction of positional notation, abacuses were a practical calculating tool. The abacus is still used to teach the fundamentals of mathematics to some children, for example, in Russia.


title: Abacus

text: Designs such as the Japanese soroban have been used for practical calculations of up to multi-digit numbers. Any particular abacus design supports multiple methods to perform calculations, including addition, subtraction, multiplication, division, and square and cube roots. Some of these methods work with non-natural numbers (numbers such as and ).


title: Abacus

text: Although calculators and computers are commonly used today instead of abacuses, abacuses remain in everyday use in some countries. Merchants, traders, and clerks in some parts of Eastern Europe, Russia, China, and Africa use abacuses. The abacus remains in common use as a scoring system in non-electronic table games. Others may use an abacus due to visual impairment that prevents the use of a calculator.


title: Abacus

text: The word "abacus" dates to at least AD 1387 when a Middle English work borrowed the word from Latin that described a sandboard abacus. The Latin word is derived from ancient Greek ("abax") which means something without a base, and colloquially, any piece of rectangular material. Alternatively, without reference to ancient texts on etymology, it has been suggested that it means "a square tablet strewn with dust", or "drawing-board covered with dust (for the use of mathematics)" (the exact shape of the Latin perhaps reflects the genitive form of the Greek word, ("abakos")). While the table strewn with dust definition is popular, some argue evidence is insufficient for that conclusion. Greek probably borrowed from a Northwest Semitic language like Phoenician, evidenced by a cognate with the Hebrew word "ʾābāq" (), or “dust” (in the post-Biblical sense "sand used as a writing surface").


title: Abacus

text: Both "abacuses" and "abaci" (soft or hard "c") are used as plurals. The user of an abacus is called an "abacist".


title: Abacus

text: The Sumerian abacus appeared between 2700–2300 BC. It held a table of successive columns which delimited the successive orders of magnitude of their sexagesimal (base 60) number system.


title: Abacus

text: Some scholars point to a character in Babylonian cuneiform that may have been derived from a representation of the abacus. It is the belief of Old Babylonian scholars, such as Ettore Carruccio, that Old Babylonians "seem to have used the abacus for the operations of addition and subtraction; however, this primitive device proved difficult to use for more complex calculations".


title: Abacus

text: Greek historian Herodotus mentioned the abacus in Ancient Egypt. He wrote that the Egyptians manipulated the pebbles from right to left, opposite in direction to the Greek left-to-right method. Archaeologists have found ancient disks of various sizes that are thought to have been used as counters. However, wall depictions of this instrument are yet to be discovered.


title: Abacus

text: At around 600 BC, Persians first began to use the abacus, during the Achaemenid Empire. Under the Parthian, Sassanian, and Iranian empires, scholars concentrated on exchanging knowledge and inventions with the countries around them – India, China, and the Roman Empire- which is how the abacus may have been exported to other countries.


title: Abacus

text: The earliest archaeological evidence for the use of the Greek abacus dates to the 5th century BC. Demosthenes (384 BC–322 BC) complained that the need to use pebbles for calculations was too difficult. A play by Alexis from the 4th century BC mentions an abacus and pebbles for accounting, and both Diogenes and Polybius use the abacus as a metaphor for human behavior, stating "that men that sometimes stood for more and sometimes for less" like the pebbles on an abacus. The Greek abacus was a table of wood or marble, pre-set with small counters in wood or metal for mathematical calculations. This Greek abacus was used in Achaemenid Persia, the Etruscan civilization, Ancient Rome, and the Western Christian world until the French Revolution.


title: Abacus

text: A tablet found on the Greek island Salamis in 1846 AD (the Salamis Tablet) dates to 300 BC, making it the oldest counting board discovered so far. It is a slab of white marble in length, wide, and thick, on which are 5 groups of markings. In the tablet's center is a set of 5 parallel lines equally divided by a vertical line, capped with a semicircle at the intersection of the bottom-most horizontal line and the single vertical line. Below these lines is a wide space with a horizontal crack dividing it. Below this crack is another group of eleven parallel lines, again divided into two sections by a line perpendicular to them, but with the semicircle at the top of the intersection; the third, sixth and ninth of these lines are marked with a cross where they intersect with the vertical line. Also from this time frame, the Darius Vase was unearthed in 1851. It was covered with pictures, including a "treasurer" holding a wax tablet in one hand while manipulating counters on a table with the other.


title: Abacus

text: The normal method of calculation in ancient Rome, as in Greece, was by moving counters on a smooth table. Originally pebbles ("calculi") were used. Later, and in medieval Europe, jetons were manufactured. Marked lines indicated units, fives, tens, etc. as in the Roman numeral system. This system of 'counter casting' continued into the late Roman empire and in medieval Europe and persisted in limited use into the nineteenth century. Due to Pope Sylvester II's reintroduction of the abacus with modifications, it became widely used in Europe again during the 11th century This abacus used beads on wires, unlike the traditional Roman counting boards, which meant the abacus could be used much faster and was more easily moved.


title: Abacus

text: Writing in the 1st century BC, Horace refers to the wax abacus, a board covered with a thin layer of black wax on which columns and figures were inscribed using a stylus.


title: Abacus

text: One example of archaeological evidence of the Roman abacus, shown nearby in reconstruction, dates to the 1st century AD. It has eight long grooves containing up to five beads in each and eight shorter grooves having either one or no beads in each. The groove marked I indicates units, X tens, and so on up to millions. The beads in the shorter grooves denote fives –five units, five tens, etc., essentially in a bi-quinary coded decimal system, related to the Roman numerals. The short grooves on the right may have been used for marking Roman "ounces" (i.e. fractions).


title: Abacus

text: The Chinese abacus, also known as the "suanpan" (算盤/算盘, lit. "calculating tray"), is typically tall and comes in various widths, depending on the operator. It usually has more than seven rods. There are two beads on each rod in the upper deck and five beads each in the bottom one. The beads are usually rounded and made of hardwood. The beads are counted by moving them up or down towards the beam; beads moved toward the beam are counted, while those moved away from it are not. One of the top beads is 5, while one of the bottom beads is 1. Each rod has a number under it, showing the place value. The "suanpan" can be reset to the starting position instantly by a quick movement along the horizontal axis to spin all the beads away from the horizontal beam at the center.


title: Abacus

text: The prototype of the Chinese abacus appeared during the Han Dynasty, and the beads are oval. The Song Dynasty and earlier used the 1:4 type or four-beads abacus similar to the modern abacus including the shape of the beads commonly known as Japanese-style abacus.


title: Abacus

text: In the early Ming Dynasty, the abacus began to appear in a 1:5 ratio. The upper deck had one bead and the bottom had five beads. In the late Ming Dynasty, the abacus styles appeared in a 2:5 ratio. The upper deck had two beads, and the bottom had five.


title: Abacus

text: Various calculation techniques were devised for "Suanpan" enabling efficient calculations. Some schools teach students how to use it.


title: Abacus

text: In the long scroll "Along the River During the Qingming Festival" painted by Zhang Zeduan during the Song dynasty (960–1297), a "suanpan" is clearly visible beside an account book and doctor's prescriptions on the counter of an apothecary's (Feibao).


title: Abacus

text: The similarity of the Roman abacus to the Chinese one suggests that one could have inspired the other, given evidence of a trade relationship between the Roman Empire and China. However, no direct connection has been demonstrated, and the similarity of the abacuses may be coincidental, both ultimately arising from counting with five fingers per hand. Where the Roman model (like most modern Korean and Japanese) has 4 plus 1 bead per decimal place, the standard "suanpan" has 5 plus 2. Incidentally, this allows use with a hexadecimal numeral system (or any base up to 18) which may have been used for traditional Chinese measures of weight. (Instead of running on wires as in the Chinese, Korean, and Japanese models, the Roman model used grooves, presumably making arithmetic calculations much slower.)


title: Abacus

text: Another possible source of the "suanpan" is Chinese counting rods, which operated with a decimal system but lacked the concept of zero as a placeholder. The zero was probably introduced to the Chinese in the Tang dynasty (618–907) when travel in the Indian Ocean and the Middle East would have provided direct contact with India, allowing them to acquire the concept of zero and the decimal point from Indian merchants and mathematicians.


title: Abacus

text: The "Abhidharmakośabhāṣya" of Vasubandhu (316-396), a Sanskrit work on Buddhist philosophy, says that the second-century CE philosopher Vasumitra said that "placing a wick (Sanskrit "vartikā") on the number one ("ekāṅka") means it is a one while placing the wick on the number hundred means it is called a hundred, and on the number one thousand means it is a thousand". It is unclear exactly what this arrangement may have been. Around the 5th century, Indian clerks were already finding new ways of recording the contents of the abacus. Hindu texts used the term "śūnya" (zero) to indicate the empty column on the abacus.


title: Abacus

text: In Japan, the abacus is called "soroban" (, lit. "counting tray"). It was imported from China in the 14th century. It was probably in use by the working class a century or more before the ruling class adopted it, as the class structure obstructed such changes. The 1:4 abacus, which removes the seldom-used second and fifth bead became popular in the 1940s.


title: Abacus

text: Today's Japanese abacus is a 1:4 type, four-bead abacus, introduced from China in the Muromachi era. It adopts the form of the upper deck one bead and the bottom four beads. The top bead on the upper deck was equal to five and the bottom one is similar to the Chinese or Korean abacus, and the decimal number can be expressed, so the abacus is designed as a one:four device. The beads are always in the shape of a diamond. The quotient division is generally used instead of the division method; at the same time, in order to make the multiplication and division digits consistently use the division multiplication. Later, Japan had a 3:5 abacus called 天三算盤, which is now in the Ize Rongji collection of Shansi Village in Yamagata City. Japan also used a 2:5 type abacus.


title: Abacus

text: The four-bead abacus spread, and became common around the world. Improvements to the Japanese abacus arose in various places. In China an aluminium frame plastic bead abacus was used. The file is next to the four beads, and pressing the "clearing" button put the upper bead in the upper position, and the lower bead in the lower position.


title: Abacus

text: The abacus is still manufactured in Japan even with the proliferation, practicality, and affordability of pocket electronic calculators. The use of the soroban is still taught in Japanese primary schools as part of mathematics, primarily as an aid to faster mental calculation. Using visual imagery can complete a calculation as quickly as a physical instrument.


title: Abacus

text: The Chinese abacus migrated from China to Korea around 1400 AD. Koreans call it "jupan" (주판), "supan" (수판) or "jusan" (주산). The four-beads abacus (1:4) was introduced during the Goryeo Dynasty. The 5:1 abacus was introduced to Korea from China during the Ming Dynasty.


title: Abacus

text: Some sources mention the use of an abacus called a "nepohualtzintzin" in ancient Aztec culture. This Mesoamerican abacus used a 5-digit base-20 system. The word Nepōhualtzintzin comes from Nahuatl, formed by the roots; "Ne" – personal -; "pōhual" or "pōhualli" – the account -; and "tzintzin" – small similar elements. Its complete meaning was taken as: counting with small similar elements. Its use was taught in the Calmecac to the "temalpouhqueh" , who were students dedicated to taking the accounts of skies, from childhood.


title: Abacus

text: The Nepōhualtzintzin was divided into two main parts separated by a bar or intermediate cord. In the left part were four beads. Beads in the first row have unitary values (1, 2, 3, and 4), and on the right side, three beads had values of 5, 10, and 15, respectively. In order to know the value of the respective beads of the upper rows, it is enough to multiply by 20 (by each row), the value of the corresponding count in the first row.


title: Abacus

text: The device featured 13 rows with 7 beads, 91 in total. This was a basic number for this culture. It had a close relation to natural phenomena, the underworld, and the cycles of the heavens. One Nepōhualtzintzin (91) represented the number of days that a season of the year lasts, two Nepōhualtzitzin (182) is the number of days of the corn's cycle, from its sowing to its harvest, three Nepōhualtzintzin (273) is the number of days of a baby's gestation, and four Nepōhualtzintzin (364) completed a cycle and approximated one year. When translated into modern computer arithmetic, the Nepōhualtzintzin amounted to the rank from 10 to 18 in floating point, which precisely calculated large and small amounts, although round off was not allowed.


title: Abacus

text: The rediscovery of the Nepōhualtzintzin was due to the Mexican engineer David Esparza Hidalgo, who in his travels throughout Mexico found diverse engravings and paintings of this instrument and reconstructed several of them in gold, jade, encrustations of shell, etc. Very old Nepōhualtzintzin are attributed to the Olmec culture, and some bracelets of Mayan origin, as well as a diversity of forms and materials in other cultures.


title: Abacus

text: Sanchez wrote in "Arithmetic in Maya" that another base 5, base 4 abacus had been found in the Yucatán Peninsula that also computed calendar data. This was a finger abacus, on one hand, 0, 1, 2, 3, and 4 were used; and on the other hand 0, 1, 2, and 3 were used. Note the use of zero at the beginning and end of the two cycles.


title: Abacus

text: The quipu of the Incas was a system of colored knotted cords used to record numerical data, like advanced tally sticks – but not used to perform calculations. Calculations were carried out using a yupana (Quechua for "counting tool"; see figure) which was still in use after the conquest of Peru. The working principle of a yupana is unknown, but in 2001 Italian mathematician De Pasquale proposed an explanation. By comparing the form of several yupanas, researchers found that calculations were based using the Fibonacci sequence 1, 1, 2, 3, 5 and powers of 10, 20, and 40 as place values for the different fields in the instrument. Using the Fibonacci sequence would keep the number of grains within any one field at a minimum.


title: Abacus

text: The Russian abacus, the "schoty" (, plural from , counting), usually has a single slanted deck, with ten beads on each wire (except one wire with four beads for quarter-ruble fractions). 4-bead wire was introduced for quarter-kopeks, which were minted until 1916. The Russian abacus is used vertically, with each wire running horizontally. The wires are usually bowed upward in the center, to keep the beads pinned to either side. It is cleared when all the beads are moved to the right. During manipulation, beads are moved to the left. For easy viewing, the middle 2 beads on each wire (the 5th and 6th bead) usually are of a different color from the other eight. Likewise, the left bead of the thousands wire (and the million wire, if present) may have a different color.


title: Abacus

text: The Russian abacus was in use in shops and markets throughout the former Soviet Union, and its usage was taught in most schools until the 1990s. Even the 1874 invention of mechanical calculator, Odhner arithmometer, had not replaced them in Russia; according to Yakov Perelman. Some businessmen attempting to import calculators into the Russian Empire were known to leave in despair after watching a skilled abacus operator. Likewise, the mass production of Felix arithmometers since 1924 did not significantly reduce abacus use in the Soviet Union. The Russian abacus began to lose popularity only after the mass production of domestic microcalculators in 1974.


title: Abacus

text: The Russian abacus was brought to France around 1820 by mathematician Jean-Victor Poncelet, who had served in Napoleon's army and had been a prisoner of war in Russia. The abacus had fallen out of use in western Europe in the 16th century with the rise of decimal notation and algorismic methods. To Poncelet's French contemporaries, it was something new. Poncelet used it, not for any applied purpose, but as a teaching and demonstration aid. The Turks and the Armenian people used abacuses similar to the Russian schoty. It was named a "coulba" by the Turks and a "choreb" by the Armenians.


title: Abacus

text: Around the world, abacuses have been used in pre-schools and elementary schools as an aid in teaching the numeral system and arithmetic.


title: Abacus

text: In Western countries, a bead frame similar to the Russian abacus but with straight wires and a vertical frame is common (see image).


title: Abacus

text: The wireframe may be used either with positional notation like other abacuses (thus the 10-wire version may represent numbers up to 9,999,999,999), or each bead may represent one unit (e.g. 74 can be represented by shifting all beads on 7 wires and 4 beads on the 8th wire, so numbers up to 100 may be represented). In the bead frame shown, the gap between the 5th and 6th wire, corresponding to the color change between the 5th and the 6th bead on each wire, suggests the latter use. Teaching multiplication, e.g. 6 times 7, may be represented by shifting 7 beads on 6 wires.


title: Abacus

text: The red-and-white abacus is used in contemporary primary schools for a wide range of number-related lessons. The twenty bead version, referred to by its Dutch name "rekenrek" ("calculating frame"), is often used, either on a string of beads or on a rigid framework.


title: Abacus

text: Physicist Richard Feynman was noted for facility in mathematical calculations. He wrote about an encounter in Brazil with a Japanese abacus expert, who challenged him to speed contests between Feynman's pen and paper, and the abacus. The abacus was much faster for addition, somewhat faster for multiplication, but Feynman was faster at division. When the abacus was used for a really difficult challenge, i.e. cube roots, Feynman won easily. However, the number chosen at random was close to a number Feynman happened to know was an exact cube, allowing him to use approximate methods.


title: Abacus

text: Learning how to calculate with the abacus may improve capacity for mental calculation. Abacus-based mental calculation (AMC), which was derived from the abacus, is the act of performing calculations, including addition, subtraction, multiplication, and division, in the mind by manipulating an imagined abacus. It is a high-level cognitive skill that runs calculations with an effective algorithm. People doing long-term AMC training show higher numerical memory capacity and experience more effectively connected neural pathways. They are able to retrieve memory to deal with complex processes. AMC involves both visuospatial and visuomotor processing that generate the visual abacus and move the imaginary beads. Since it only requires that the final position of beads be remembered, it takes less memory and less computation time.


title: Abacus

text: The binary abacus is used to explain how computers manipulate numbers. The abacus shows how numbers, letters, and signs can be stored in a binary system on a computer, or via ASCII. The device consists of a series of beads on parallel wires arranged in three separate rows. The beads represent a switch on the computer in either an "on" or "off" position.


title: Abacus

text: An adapted abacus, invented by Tim Cranmer, and called a Cranmer abacus is commonly used by visually impaired users. A piece of soft fabric or rubber is placed behind the beads, keeping them in place while the users manipulate them. The device is then used to perform the mathematical functions of multiplication, division, addition, subtraction, square root, and cube root.


title: Abacus

text: Although blind students have benefited from talking calculators, the abacus is often taught to these students in early grades. Blind students can also complete mathematical assignments using a braille-writer and Nemeth code (a type of braille code for mathematics) but large multiplication and long division problems are tedious. The abacus gives these students a tool to compute mathematical problems that equals the speed and mathematical knowledge required by their sighted peers using pencil and paper. Many blind people find this number machine a useful tool throughout life.


title: California Gold Rush

text: The California Gold Rush (1848–1855) was a gold rush that began on January 24, 1848, when gold was found by James W. Marshall at Sutter's Mill in Coloma, California. The news of gold brought approximately 300,000 people to California from the rest of the United States and abroad. The sudden influx of gold into the money supply reinvigorated the American economy; the sudden population increase allowed California to go rapidly to statehood, in the Compromise of 1850. The Gold Rush had severe effects on Native Californians and accelerated the Native American population's decline from disease, starvation and the California genocide.


title: California Gold Rush

text: The effects of the Gold Rush were substantial. Whole indigenous societies were attacked and pushed off their lands by the gold-seekers, called "forty-niners" (referring to 1849, the peak year for Gold Rush immigration). Outside of California, the first to arrive were from Oregon, the Sandwich Islands (Hawaii) and Latin America in late 1848. Of the approximately 300,000 people who came to California during the Gold Rush, about half arrived by sea and half came overland on the California Trail and the Gila River trail; forty-niners often faced substantial hardships on the trip. While most of the newly arrived were Americans, the gold rush attracted thousands from Latin America, Europe, Australia and China. Agriculture and ranching expanded throughout the state to meet the needs of the settlers. San Francisco grew from a small settlement of about 200 residents in 1846 to a boomtown of about 36,000 by 1852. Roads, churches, schools and other towns were built throughout California. In 1849 a state constitution was written. The new constitution was adopted by referendum vote; the future state's interim first governor and legislature were chosen. In September 1850, California became a state.


title: California Gold Rush

text: At the beginning of the Gold Rush, there was no law regarding property rights in the goldfields and a system of "staking claims" was developed. Prospectors retrieved the gold from streams and riverbeds using simple techniques, such as panning. Although mining caused environmental harm, more sophisticated methods of gold recovery were developed and later adopted around the world. New methods of transportation developed as steamships came into regular service. By 1869, railroads were built from California to the eastern United States. At its peak, technological advances reached a point where significant financing was required, increasing the proportion of gold companies to individual miners. Gold worth tens of billions of today's US dollars was recovered, which led to great wealth for a few, though many who participated in the California Gold Rush earned little more than they had started with.


title: California Gold Rush

text: Gold was discovered in California as early as March 9, 1842, at Rancho San Francisco, in the mountains north of present-day Los Angeles. Californian native Francisco Lopez was searching for stray horses and stopped on the bank of a small creek (in today's Placerita Canyon), about east of present-day Newhall, California, and about northwest of L.A. While the horses grazed, Lopez dug up some wild onions and found a small gold nugget in the roots among the bulbs. He looked further and found more gold. Lopez took the gold to authorities who confirmed its worth. Lopez and others began to search for other streambeds with gold deposits in the area. They found several in the northeastern section of the forest, within present-day Ventura County. In November, some of the gold was sent to the U.S. Mint, although otherwise attracted little notice. In 1843, Lopez found gold in San Feliciano Canyon near his first discovery. Mexican miners from Sonora worked the placer deposits until 1846. Minor finds of gold in California were also made by Mission Indians prior to 1848. The friars instructed them to keep its location secret to avoid a gold rush.


title: California Gold Rush

text: In January 1847, nine months into the Mexican–American War, the Treaty of Cahuenga was signed, leading to the resolution of the military conflict in Alta California (Upper California). On January 24, 1848, James W. Marshall found shiny metal in the tailrace of a lumber mill he was building for Sacramento pioneer John Sutter—known as Sutter's Mill, near Coloma on the American River. Marshall brought what he found to Sutter, and the two privately tested the metal. After the tests showed that it was gold, Sutter expressed dismay, wanting to keep the news quiet because he feared what would happen to his plans for an agricultural empire if there were a gold rush in the region. The Mexican–American War ended on February 2 with the signing of the Treaty of Guadalupe Hidalgo, which formally transferred California to the United States.


title: California Gold Rush

text: Having sworn all concerned at the mill to secrecy, in February 1848, Sutter sent Charles Bennett to Monterey to meet with Colonel Mason, the chief U.S. official in California, to secure the mineral rights of the land where the mill stood. Bennett was not to tell anyone of the discovery of gold, but when he stopped at Benicia, he heard talk about the discovery of coal near Mount Diablo, and he blurted out the discovery of gold. He continued to San Francisco, where again, he could not keep the secret. At Monterey, Mason declined to make any judgement of title to lands and mineral rights, and Bennett for the third time revealed the gold discovery.


title: California Gold Rush

text: By March 1848, rumors of the discovery were confirmed by San Francisco newspaper publisher and merchant Samuel Brannan. Brannan hurriedly set up a store to sell gold prospecting supplies, and he walked through the streets of San Francisco, holding aloft a vial of gold, shouting "Gold! Gold! Gold from the American River!"


title: California Gold Rush

text: On August 19, 1848, the "New York Herald" was the first major newspaper on the East Coast to report the discovery of gold. On December 5, 1848, US President James K. Polk confirmed the discovery of gold in an address to Congress. As a result, individuals seeking to benefit from the gold rush—later called the "forty-niners"—began moving to the Gold Country of California or "Mother Lode" from other countries and from other parts of the United States. As Sutter had feared, his business plans were ruined after his workers left in search of gold, and squatters took over his land and stole his crops and cattle.


title: California Gold Rush

text: San Francisco had been a tiny settlement before the rush began. When residents learned about the discovery, it at first became a ghost town of abandoned ships and businesses, but then boomed as merchants and new people arrived. The population of San Francisco increased quickly from about 1,000 in 1848 to 25,000 full-time residents by 1850. Miners lived in tents, wood shanties, or deck cabins removed from abandoned ships.


title: California Gold Rush

text: In what has been referred to as the "first world-class gold rush," there was no easy way to get to California; forty-niners faced hardship and often death on the way. At first, most s, as they were also known, traveled by sea. From the East Coast, a sailing voyage around the tip of South America would take four to five months, and cover approximately . An alternative was to sail to the Atlantic side of the Isthmus of Panama, take canoes and mules for a week through the jungle, and then on the Pacific side, wait for a ship sailing for San Francisco. There was also a route across Mexico starting at Veracruz. The companies providing such transportation created vast wealth among their owners and included the U.S. Mail Steamship Company, the federally subsidized Pacific Mail Steamship Company, and the Accessory Transit Company. Many gold-seekers took the overland route across the continental United States, particularly along the California Trail. Each of these routes had its own deadly hazards, from shipwreck to typhoid fever and cholera. In the early years of the rush, much of the population growth in the San Francisco area was due to steamship travel from New York City through overland portages in Nicaragua and Panama and then back up by steamship to San Francisco.


title: California Gold Rush

text: While traveling, many steamships from the eastern seaboard required the passengers to bring kits, which were typically full of personal belongings such as clothes, guidebooks, tools, etc. In addition to personal belongings, Argonauts were required to bring barrels full of beef, biscuits, butter, pork, rice, and salt. While on the steamships, travelers could talk to each other, smoke, fish, and other activities depending on the ship they traveled. Still, the dominant activity held throughout the steamships was gambling, which was ironic because segregation between wealth gaps was prominent throughout the ships. Everything was segregated between the rich vs. the poor. There were different levels of travel one could pay for to get to California. The cheaper steamships tended to have longer routes. In contrast, the more expensive would get passengers to California quicker. There were clear social and economic distinctions between those who traveled together, being that those who spent more money would receive accommodations that others were not allowed. They would do this with the clear intent to distinguish their higher class power over those that could not afford those accommodations.


title: California Gold Rush

text: Supply ships arrived in San Francisco with goods to supply the needs of the growing population. When hundreds of ships were abandoned after their crews deserted to go into the goldfields, many ships were converted to warehouses, stores, taverns, hotels, and one into a jail. As the city expanded and new places were needed on which to build, many ships were destroyed and used as landfill.


title: California Gold Rush

text: Within a few years, there was an important but lesser-known surge of prospectors into far Northern California, specifically into present-day Siskiyou, Shasta and Trinity Counties. Discovery of gold nuggets at the site of present-day Yreka in 1851 brought thousands of gold-seekers up the Siskiyou Trail and throughout California's northern counties.


title: California Gold Rush

text: Settlements of the Gold Rush era, such as Portuguese Flat on the Sacramento River, sprang into existence and then faded. The Gold Rush town of Weaverville on the Trinity River today retains the oldest continuously used Taoist temple in California, a legacy of Chinese miners who came. While there are not many Gold Rush era ghost towns still in existence, the remains of the once-bustling town of Shasta have been preserved in a California State Historic Park in Northern California.


title: California Gold Rush

text: By 1850, most of the easily accessible gold had been collected, and attention turned to extracting gold from more difficult locations. Faced with gold increasingly difficult to retrieve, Americans began to drive out foreigners to get at the most accessible gold that remained. The new California State Legislature passed a foreign miners tax of twenty dollars per month ($ per month as of 2022), and American prospectors began organized attacks on foreign miners, particularly Latin Americans and Chinese.


title: California Gold Rush

text: In addition, the huge numbers of newcomers were driving Native Americans out of their traditional hunting, fishing and food-gathering areas. To protect their homes and livelihood, some Native Americans responded by attacking the miners. This provoked counter-attacks on native villages. The Native Americans, out-gunned, were often slaughtered. Those who escaped massacres were many times unable to survive without access to their food-gathering areas, and they starved to death. Novelist and poet Joaquin Miller vividly captured one such attack in his semi-autobiographical work, "Life Amongst the Modocs."


title: California Gold Rush

text: The first people to rush to the goldfields, beginning in the spring of 1848, were the residents of California themselves—primarily agriculturally oriented Americans and Europeans living in Northern California, along with Native Californians and some "Californios" (Spanish-speaking Californians; at the time, commonly referred to in English as simply 'Californians'). These first miners tended to be families in which everyone helped in the effort. Women and children of all ethnicities were often found panning next to the men. Some enterprising families set up boarding houses to accommodate the influx of men; in such cases, the women often brought in steady income while their husbands searched for gold.


title: California Gold Rush

text: Word of the Gold Rush spread slowly at first. The earliest gold-seekers were people who lived near California or people who heard the news from ships on the fastest sailing routes from California. The first large group of Americans to arrive were several thousand Oregonians who came down the Siskiyou Trail. Next came people from the Sandwich Islands, and several thousand Latin Americans, including people from Mexico, from Peru and from as far away as Chile, both by ship and overland. By the end of 1848, some 6,000 Argonauts had come to California.


title: California Gold Rush

text: Only a small number (probably fewer than 500) traveled overland from the United States that year. Some of these "forty-eighters", as the earliest gold-seekers were sometimes called, were able to collect large amounts of easily accessible gold—in some cases, thousands of dollars worth each day. Even ordinary prospectors averaged daily gold finds worth 10 to 15 times the daily wage of a laborer on the East Coast. A person could work for six months in the goldfields and find the equivalent of six years' wages back home. Some hoped to get rich quick and return home, and others wished to start businesses in California.


title: California Gold Rush

text: By the beginning of 1849, word of the Gold Rush had spread around the world, and an overwhelming number of gold-seekers and merchants began to arrive from virtually every continent. The largest group of forty-niners in 1849 were Americans, arriving by the tens of thousands overland across the continent and along various sailing routes (the name "forty-niner" was derived from the year 1849). Many from the East Coast negotiated a crossing of the Appalachian Mountains, taking to riverboats in Pennsylvania, poling the keelboats to Missouri River wagon train assembly ports, and then travelling in a wagon train along the California Trail. Many others came by way of the Isthmus of Panama and the steamships of the Pacific Mail Steamship Company. Australians and New Zealanders picked up the news from ships carrying Hawaiian newspapers, and thousands, infected with "gold fever", boarded ships for California.


title: California Gold Rush

text: Forty-niners came from Latin America, particularly from the Mexican mining districts near Sonora and Chile. Gold-seekers and merchants from Asia, primarily from China, began arriving in 1849, at first in modest numbers to "Gum San" ("Gold Mountain"), the name given to California in Chinese. The first immigrants from Europe, reeling from the effects of the Revolutions of 1848 and with a longer distance to travel, began arriving in late 1849, mostly from France, with some Germans, Italians, and Britons.


title: California Gold Rush

text: It is estimated that approximately 90,000 people arrived in California in 1849—about half by land and half by sea. Of these, perhaps 50,000 to 60,000 were Americans, and the rest were from other countries. By 1855, it is estimated at least 300,000 gold-seekers, merchants, and other immigrants had arrived in California from around the world. The largest group continued to be Americans, but there were tens of thousands each of Mexicans, Chinese, Britons, Australians, French, and Latin Americans, together with many smaller groups of miners, such as African Americans, Filipinos, Basques and Turks.


title: California Gold Rush

text: People from small villages in the hills near Genova, Italy were among the first to settle permanently in the Sierra Nevada foothills; they brought with them traditional agricultural skills, developed to survive cold winters. A modest number of miners of African ancestry (probably less than 4,000) had come from the Southern States, the Caribbean and Brazil.


title: California Gold Rush

text: A number of immigrants were from China. Several hundred Chinese arrived in California in 1849 and 1850, and in 1852 more than 20,000 landed in San Francisco. Their distinctive dress and appearance was highly recognizable in the goldfields. Chinese miners suffered enormously, enduring violent racism from white miners who aimed their frustrations at foreigners. Further animosity toward the Chinese led to legislation such as the Chinese Exclusion Act and Foreign Miners Tax.


title: California Gold Rush

text: There were also women in the Gold Rush. However, their numbers were small. Of the 40,000 people who arrived by ship to the San Francisco Bay in 1849, only 700 were women (including those who were poor, wealthy, entrepreneurs, prostitutes, single, and married). They were of various ethnicities including Anglo-American, African-American, Hispanic, Native, European, Chinese, and Jewish. The reasons they came varied: some came with their husbands, refusing to be left behind to fend for themselves, some came because their husbands sent for them, and others came (singles and widows) for the adventure and economic opportunities. On the trail many people died from accidents, cholera, fever, and myriad other causes, and many women became widows before even setting eyes on California. While in California, women became widows quite frequently due to mining accidents, disease, or mining disputes of their husbands. Life in the goldfields offered opportunities for women to break from their traditional work.


title: California Gold Rush

text: When the Gold Rush began, the California goldfields were peculiarly lawless places. When gold was discovered at Sutter's Mill, California was still technically part of Mexico, under American military occupation as the result of the Mexican–American War. With the signing of the treaty ending the war on February 2, 1848, California became a possession of the United States, but it was not a formal "territory" and did not become a state until September 9, 1850. California existed in the unusual condition of a region under military control. There was no civil legislature, executive or judicial body for the entire region. Local residents operated under a confusing and changing mixture of Mexican rules, American principles, and personal dictates. Lax enforcement of federal laws, such as the Fugitive Slave Act of 1850, encouraged the arrival of free blacks and escaped slaves.


title: California Gold Rush

text: While the treaty ending the Mexican–American War obliged the United States to honor Mexican land grants, almost all the goldfields were outside those grants. Instead, the goldfields were primarily on "public land", meaning land formally owned by the United States government. However, there were no legal rules yet in place, and no practical enforcement mechanisms.


title: California Gold Rush

text: The benefit to the forty-niners was that the gold was simply "free for the taking" at first. In the goldfields at the beginning, there was no private property, no licensing fees, and no taxes. The miners informally adapted Mexican mining law that had existed in California. For example, the rules attempted to balance the rights of early arrivers at a site with later arrivers; a "claim" could be "staked" by a prospector, but that claim was valid only as long as it was being actively worked.


title: California Gold Rush

text: Miners worked at a claim only long enough to determine its potential. If a claim was deemed as low-value—as most were—miners would abandon the site in search of a better one. In the case where a claim was abandoned or not worked upon, other miners would "claim-jump" the land. "Claim-jumping" meant that a miner began work on a previously claimed site. Disputes were often handled personally and violently, and were sometimes addressed by groups of prospectors acting as arbitrators. This often led to heightened ethnic tensions. In some areas the influx of many prospectors could lead to a reduction of the existing claim size by simple pressure.


title: California Gold Rush

text: Approximately four hundred million years ago, California lay at the bottom of a large sea; underwater volcanoes deposited lava and minerals (including gold) onto the sea floor. By tectonic forces these minerals and rocks came to the surface of the Sierra Nevada, and eroded. Water carried the exposed gold downstream and deposited it in quiet gravel beds along the sides of old rivers and streams. The forty-niners first focused their efforts on these deposits of gold.


title: California Gold Rush

text: Because the gold in the California gravel beds was so richly concentrated, early forty-niners were able to retrieve loose gold flakes and nuggets with their hands, or simply "pan" for gold in rivers and streams. Panning cannot take place on a large scale, and industrious miners and groups of miners graduated to placer mining, using "cradles" and "rockers" or "long-toms" to process larger volumes of gravel. Miners would also engage in "coyoteing", a method that involved digging a shaft deep into placer deposits along a stream. Tunnels were then dug in all directions to reach the richest veins of pay dirt.


title: California Gold Rush

text: In the most complex placer mining, groups of prospectors would divert the water from an entire river into a sluice alongside the river and then dig for gold in the newly exposed river bottom. Modern estimates are that as much as 12 million ounces (370 t) of gold were removed in the first five years of the Gold Rush.


title: California Gold Rush

text: In the next stage, by 1853, hydraulic mining was used on ancient gold-bearing gravel beds on hillsides and bluffs in the goldfields. In a modern style of hydraulic mining first developed in California, and later used around the world, a high-pressure hose directed a powerful stream or jet of water at gold-bearing gravel beds. The loosened gravel and gold would then pass over sluices, with the gold settling to the bottom where it was collected. By the mid-1880s, it is estimated that 11 million ounces (340 t) of gold (worth approximately US$15 billion at December 2010 prices) had been recovered by hydraulic mining.


title: California Gold Rush

text: A byproduct of these extraction methods was that large amounts of gravel, silt, heavy metals, and other pollutants went into streams and rivers. many areas still bear the scars of hydraulic mining, since the resulting exposed earth and downstream gravel deposits do not support plant life.


title: California Gold Rush

text: After the Gold Rush had concluded, gold recovery operations continued. The final stage to recover loose gold was to prospect for gold that had slowly washed down into the flat river bottoms and sandbars of California's Central Valley and other gold-bearing areas of California (such as Scott Valley in Siskiyou County). By the late 1890s, dredging technology (also invented in California) had become economical, and it is estimated that more than 20 million ounces (620 t) were recovered by dredging.


title: California Gold Rush

text: Both during the Gold Rush and in the decades that followed, gold-seekers also engaged in "hard-rock" mining, extracting the gold directly from the rock that contained it (typically quartz), usually by digging and blasting to follow and remove veins of the gold-bearing quartz. Once the gold-bearing rocks were brought to the surface, the rocks were crushed and the gold separated, either using separation in water, using its density difference from quartz sand, or by washing the sand over copper plates coated with mercury (with which gold forms an amalgam). Loss of mercury in the amalgamation process was a source of environmental contamination.


title: California Gold Rush

text: Eventually, hard-rock mining became the single largest source of gold produced in the Gold Country. The total production of gold in California from then until now is estimated at 118 million ounces (3700 t).


title: California Gold Rush

text: Recent scholarship confirms that merchants made far more money than miners during the Gold Rush. The wealthiest man in California during the early years of the rush was Samuel Brannan, a tireless self-promoter, shopkeeper and newspaper publisher. Brannan opened the first supply stores in Sacramento, Coloma, and other spots in the goldfields. Just as the rush began he purchased all the prospecting supplies available in San Francisco and re-sold them at a substantial profit.


title: California Gold Rush

text: Some gold-seekers made a significant amount of money. On average, half the gold-seekers made a modest profit, after taking all expenses into account; economic historians have suggested that white miners were more successful than black, Indian, or Chinese miners. However, taxes such as the California foreign miners tax passed in 1851, targeted mainly Latino miners and kept them from making as much money as whites, who did not have any taxes imposed on them. In California most late arrivals made little or wound up losing money. Similarly, many unlucky merchants set up in settlements that disappeared, or which succumbed to one of the calamitous fires that swept the towns that sprang up. By contrast, a businessman who went on to great success was Levi Strauss, who first began selling denim overalls in San Francisco in 1853.


title: California Gold Rush

text: Other businessmen reaped great rewards in retail, shipping, entertainment, lodging, or transportation. Boardinghouses, food preparation, sewing, and laundry were highly profitable businesses often run by women (married, single, or widowed) who realized men would pay well for a service done by a woman. Brothels also brought in large profits, especially when combined with saloons and gaming houses.


title: California Gold Rush

text: By 1855, the economic climate had changed dramatically. Gold could be retrieved profitably from the goldfields only by medium to large groups of workers, either in partnerships or as employees. By the mid-1850s, it was the owners of these gold-mining companies who made the money. Also, the population and economy of California had become large and diverse enough that money could be made in a wide variety of conventional businesses.


title: California Gold Rush

text: Once extracted, the gold itself took many paths. First, much of the gold was used locally to purchase food, supplies and lodging for the miners. It also went towards entertainment, which consisted of anything from a traveling theater to alcohol, gambling, and prostitutes. These transactions often took place using the recently recovered gold, carefully weighed out. These merchants and vendors, in turn, used the gold to purchase supplies from ship captains or packers bringing goods to California.


title: California Gold Rush

text: The gold then left California aboard ships or mules to go to the makers of the goods from around the world. A second path was the Argonauts themselves who, having personally acquired a sufficient amount, sent the gold home, or returned home taking with them their hard-earned "diggings". For example, one estimate is that some US$80 million worth of California gold (equivalent to US$ billion today) was sent to France by French prospectors and merchants.


title: California Gold Rush

text: As the Gold Rush progressed, local banks and gold dealers issued "banknotes" or "drafts"—locally accepted paper currency—in exchange for gold, and private mints created private gold coins. With the building of the San Francisco Mint in 1854, gold bullion was turned into official United States gold coins for circulation. The gold was also later sent by California banks to U.S. national banks in exchange for national paper currency to be used in the booming California economy.


title: California Gold Rush

text: The arrival of hundreds of thousands of new people in California within a few years, compared to a population of some 15,000 Europeans and "Californios" beforehand, had many dramatic effects.


title: California Gold Rush

text: A 2017 study attributes the record-long economic expansion of the United States in the recession-free period of 1841–1856 primarily to "a boom in transportation-goods investment following the discovery of gold in California."


title: California Gold Rush

text: The Gold Rush propelled California from a sleepy, little-known backwater to a center of the global imagination and the destination of hundreds of thousands of people. The new immigrants often showed remarkable inventiveness and civic-mindedness. For example, in the midst of the Gold Rush, towns and cities were chartered, a state constitutional convention was convened, a state constitution written, elections held, and representatives sent to Washington, D.C. to negotiate the admission of California as a state.


title: California Gold Rush

text: Large-scale agriculture (California's second "Gold Rush") began during this time. Roads, schools, churches, and civic organizations quickly came into existence. The vast majority of the immigrants were Americans. Pressure grew for better communications and political connections to the rest of the United States, leading to statehood for California on September 9, 1850, in the Compromise of 1850 as the state of the United States.


title: California Gold Rush

text: Between 1847 and 1870, the population of San Francisco increased from 500 to 150,000. The Gold Rush wealth and population increase led to significantly improved transportation between California and the East Coast. The Panama Railway, spanning the Isthmus of Panama, was finished in 1855. Steamships, including those owned by the Pacific Mail Steamship Company, began regular service from San Francisco to Panama, where passengers, goods and mail would take the train across the Isthmus and board steamships headed to the East Coast. One ill-fated journey, that of the S.S. "Central America", ended in disaster as the ship sank in a hurricane off the coast of the Carolinas in 1857, with approximately three tons of California gold aboard.


title: California Gold Rush

text: The human and environmental costs of the Gold Rush were substantial. Native Americans, dependent on traditional hunting, gathering and agriculture, became the victims of starvation and disease, as gravel, silt and toxic chemicals from prospecting operations killed fish and destroyed habitats. The surge in the mining population also resulted in the disappearance of game and food gathering locales as gold camps and other settlements were built amidst them. Later farming spread to supply the settlers' camps, taking more land away from the Native Americans.


title: California Gold Rush

text: In some areas, systematic attacks against tribespeople in or near mining districts occurred. Various conflicts were fought between natives and settlers. Miners often saw Native Americans as impediments to their mining activities. Ed Allen, interpretive lead for Marshall Gold Discovery State Historic Park, reported that there were times when miners would kill up to 50 or more Natives in one day. Retribution attacks on solitary miners could result in larger scale attacks against Native populations, at times tribes or villages not involved in the original act. During the 1852 Bridge Gulch Massacre, a group of settlers attacked a band of Wintu Indians in response to the killing of a citizen named J. R. Anderson. After his killing, the sheriff led a group of men to track down the Indians, whom the men then attacked. Only three children survived the massacre that was against a different band of Wintu than the one that had killed Anderson.


title: California Gold Rush

text: Historian Benjamin Madley recorded the numbers of killings of California Indians between 1846 and 1873 and estimated that during this period at least 9,400 to 16,000 California Indians were killed by non-Indians, mostly occurring in more than 370 massacres (defined as the "intentional killing of five or more disarmed combatants or largely unarmed noncombatants, including women, children, and prisoners, whether in the context of a battle or otherwise"). According to demographer Russell Thornton, between 1849 and 1890, the Indigenous population of California fell below 20,000 – primarily because of the killings. According to the government of California, some 4,500 Native Americans suffered violent deaths between 1849 and 1870. Furthermore, California stood in opposition of ratifying the eighteen treaties signed between tribal leaders and federal agents in 1851. The state government, in support of miner activities funded and supported death squads, appropriating over 1 million dollars towards the funding and operation of the paramilitary organizations.


title: California Gold Rush

text: Peter Burnett, California's first governor declared that California was a battleground between the races and that there were only two options towards California Indians, extermination or removal. "That a war of extermination will continue to be waged between the two races until the Indian race becomes extinct, must be expected. While we cannot anticipate the result with but painful regret, the inevitable destiny of the race is beyond the power and wisdom of man to avert." For Burnett, like many of his contemporaries, the genocide was part of God's plan, and it was necessary for Burnett's constituency to move forward in California. The Act for the Government and Protection of Indians, passed on April 22, 1850, by the California Legislature, allowed settlers to capture and use Native people as bonded workers, prohibited Native peoples' testimony against settlers, and allowed the adoption of Native children by settlers, often for labor purposes.


title: California Gold Rush

text: After the initial boom had ended, explicitly anti-foreign and racist attacks, laws and confiscatory taxes sought to drive out foreigners—in addition to Native Americans—from the mines, especially the Chinese and Latin American immigrants mostly from Sonora, Mexico and Chile. The toll on the American immigrants was severe as well: one in twelve forty-niners perished, as the death and crime rates during the Gold Rush were extraordinarily high, and the resulting vigilantism also took its toll.


title: California Gold Rush

text: The Gold Rush stimulated economies around the world as well. Farmers in Chile, Australia, and Hawaii found a huge new market for their food; British manufactured goods were in high demand; clothing and even prefabricated houses arrived from China. The return of large amounts of California gold to pay for these goods raised prices and stimulated investment and the creation of jobs around the world. Australian prospector Edward Hargraves, noting similarities between the geography of California and his home country, returned to Australia to discover gold and spark the Australian gold rushes. Preceding the Gold Rush, the United States was on a bi-metallic standard, but the sudden increase in physical gold supply increased the relative value of physical silver and drove silver money from circulation. The increase in gold supply also created a monetary supply shock.


title: California Gold Rush

text: Within a few years after the end of the Gold Rush, in 1863, the groundbreaking ceremony for the western leg of the First transcontinental railroad was held in Sacramento. The line's completion, some six years later, financed in part with Gold Rush money, united California with the central and eastern United States. Travel that had taken weeks or even months could now be accomplished in days.


title: California Gold Rush

text: As the California Gold Rush brought a disproportionate population of men and set an environment of experimental lawlessness separate from the bounds of standard society, conventional American gender roles came into question. In the large absence of women, these migrant young men were made to reorganize their social and sexual practices, leading to cross-gender practices that most often took place as cross-dressing. Dance events were a notable social space for cross-dressing, where a piece of cloth (such as a handkerchief or sackcloth patch) would denote a 'woman.' Beyond social events, these subverted gender expectations continued into domestic duties as well. Though cross-dressing occurred most frequently with men as women, the reverse also applied.


title: California Gold Rush

text: These miners and merchants of various genders and gendered appearances, encouraged by the social fluidity and population limitations of the Wild West, shaped the beginnings of San Francisco's prominent queer history.


title: California Gold Rush

text: California's name became indelibly connected with the Gold Rush, and fast success in a new world became known as the "California Dream." California was perceived as a place of new beginnings, where great wealth could reward hard work and good luck. Historian H. W. Brands noted that in the years after the Gold Rush, the California Dream spread across the nation:


title: California Gold Rush

text: Overnight California gained the international reputation as the "golden state". Generations of immigrants have been attracted by the California Dream. California farmers, oil drillers, movie makers, airplane builders, computer and microchip makers, and "dot-com" entrepreneurs have each had their boom times in the decades after the Gold Rush.


title: California Gold Rush

text: In addition, the standard route shield of state highways in California is in the shape of a miner's spade to honor the California Gold Rush. Today, the aptly named State Route 49 travels through the Sierra Nevada foothills, connecting many Gold Rush-era towns such as Placerville, Auburn, Grass Valley, Nevada City, Coloma, Jackson, and Sonora. This state highway also passes very near Columbia State Historic Park, a protected area encompassing the historic business district of the town of Columbia; the park has preserved many Gold Rush-era buildings, which are presently occupied by tourist-oriented businesses.


title: California Gold Rush

text: The literary history of the Gold Rush is reflected in the works of Mark Twain ("The Celebrated Jumping Frog of Calaveras County"), Bret Harte ("A Millionaire of Rough-and-Ready"), Joaquin Miller ("Life Amongst the Modocs"), and many others.


title: Adrenal gland

text: The adrenal glands (also known as suprarenal glands) are endocrine glands that produce a variety of hormones including adrenaline and the steroids aldosterone and cortisol. They are found above the kidneys. Each gland has an outer cortex which produces steroid hormones and an inner medulla. The adrenal cortex itself is divided into three main zones: the zona glomerulosa, the zona fasciculata and the zona reticularis.


title: Adrenal gland

text: The adrenal cortex produces three main types of steroid hormones: mineralocorticoids, glucocorticoids, and androgens. Mineralocorticoids (such as aldosterone) produced in the zona glomerulosa help in the regulation of blood pressure and electrolyte balance. The glucocorticoids cortisol and cortisone are synthesized in the zona fasciculata; their functions include the regulation of metabolism and immune system suppression. The innermost layer of the cortex, the zona reticularis, produces androgens that are converted to fully functional sex hormones in the gonads and other target organs. The production of steroid hormones is called steroidogenesis, and involves a number of reactions and processes that take place in cortical cells. The medulla produces the catecholamines, which function to produce a rapid response throughout the body in stress situations.


title: Adrenal gland

text: A number of endocrine diseases involve dysfunctions of the adrenal gland. Overproduction of cortisol leads to Cushing's syndrome, whereas insufficient production is associated with Addison's disease. Congenital adrenal hyperplasia is a genetic disease produced by dysregulation of endocrine control mechanisms. A variety of tumors can arise from adrenal tissue and are commonly found in medical imaging when searching for other diseases.


title: Adrenal gland

text: The adrenal glands are located on both sides of the body in the retroperitoneum, above and slightly medial to the kidneys. In humans, the right adrenal gland is pyramidal in shape, whereas the left is semilunar or crescent shaped and somewhat larger. The adrenal glands measure approximately 5 cm in length, 3 cm in width, and up to 1 cm in thickness. Their combined weight in an adult human ranges from 7 to 10 grams. The glands are yellowish in colour.


title: Adrenal gland

text: The adrenal glands are surrounded by a fatty capsule and lie within the renal fascia, which also surrounds the kidneys. A weak septum (wall) of connective tissue separates the glands from the kidneys. The adrenal glands are directly below the diaphragm, and are attached to the crura of the diaphragm by the renal fascia.


title: Adrenal gland

text: Each adrenal gland has two distinct parts, each with a unique function, the outer adrenal cortex and the inner medulla, both of which produce hormones.


title: Adrenal gland

text: The adrenal cortex is the outer region and also the largest part of an adrenal gland. It is divided into three separate zones: zona glomerulosa, zona fasciculata and zona reticularis. Each zone is responsible for producing specific hormones.


title: Adrenal gland

text: The adrenal cortex is the outermost layer of the adrenal gland. Within the cortex are three layers, called "zones". When viewed under a microscope each layer has a distinct appearance, and each has a different function. The adrenal cortex is devoted to production of hormones, namely aldosterone, cortisol, and androgens.


title: Adrenal gland

text: The outermost zone of the adrenal cortex is the zona glomerulosa. It lies immediately under the fibrous capsule of the gland. Cells in this layer form oval groups, separated by thin strands of connective tissue from the fibrous capsule of the gland and carry wide capillaries.


title: Adrenal gland

text: This layer is the main site for production of aldosterone, a mineralocorticoid, by the action of the enzyme aldosterone synthase. Aldosterone plays an important role in the long-term regulation of blood pressure.


title: Adrenal gland

text: The zona fasciculata is situated between the zona glomerulosa and zona reticularis. Cells in this layer are responsible for producing glucocorticoids such as cortisol. It is the largest of the three layers, accounting for nearly 80% of the volume of the cortex. In the zona fasciculata, cells are arranged in columns radially oriented towards the medulla. Cells contain numerous lipid droplets, abundant mitochondria and a complex smooth endoplasmic reticulum.


title: Adrenal gland

text: The innermost cortical layer, the zona reticularis, lies directly adjacent to the medulla. It produces androgens, mainly dehydroepiandrosterone (DHEA), DHEA sulfate (DHEA-S), and androstenedione (the precursor to testosterone) in humans. Its small cells form irregular cords and clusters, separated by capillaries and connective tissue. The cells contain relatively small quantities of cytoplasm and lipid droplets, and sometimes display brown lipofuscin pigment.


title: Adrenal gland

text: The adrenal medulla is at the centre of each adrenal gland, and is surrounded by the adrenal cortex. The chromaffin cells of the medulla are the body's main source of the catecholamines, such as adrenaline and noradrenaline, released by the medulla. Approximately 20% noradrenaline (norepinephrine) and 80% adrenaline (epinephrine) are secreted here.


title: Adrenal gland

text: The adrenal medulla is driven by the sympathetic nervous system via preganglionic fibers originating in the thoracic spinal cord, from vertebrae T5–T11. Because it is innervated by preganglionic nerve fibers, the adrenal medulla can be considered as a specialized sympathetic ganglion. Unlike other sympathetic ganglia, however, the adrenal medulla lacks distinct synapses and releases its secretions directly into the blood.


title: Adrenal gland

text: The adrenal glands have one of the greatest blood supply rates per gram of tissue of any organ: up to 60 small arteries may enter each gland. Three arteries usually supply each adrenal gland:


title: Adrenal gland

text: These blood vessels supply a network of small arteries within the capsule of the adrenal glands. Thin strands of the capsule enter the glands, carrying blood to them.


title: Adrenal gland

text: The central adrenomedullary vein, in the adrenal medulla, is an unusual type of blood vessel. Its structure is different from the other veins in that the smooth muscle in its tunica media (the middle layer of the vessel) is arranged in conspicuous, longitudinally oriented bundles.


title: Adrenal gland

text: The adrenal glands may not develop at all, or may be fused in the midline behind the aorta. These are associated with other congenital abnormalities, such as failure of the kidneys to develop, or fused kidneys. The gland may develop with a partial or complete absence of the cortex, or may develop in an unusual location.


title: Adrenal gland

text: The adrenal gland secretes a number of different hormones which are metabolised by enzymes either within the gland or in other parts of the body. These hormones are involved in a number of essential biological functions.


title: Adrenal gland

text: Corticosteroids are a group of steroid hormones produced from the cortex of the adrenal gland, from which they are named.


title: Adrenal gland

text: The adrenal gland produces aldosterone, a mineralocorticoid, which is important in the regulation of salt ("mineral") balance and blood volume. In the kidneys, aldosterone acts on the distal convoluted tubules and the collecting ducts by increasing the reabsorption of sodium and the excretion of both potassium and hydrogen ions. Aldosterone is responsible for the reabsorption of about 2% of filtered glomerular filtrate. Sodium retention is also a response of the distal colon and sweat glands to aldosterone receptor stimulation. Angiotensin II and extracellular potassium are the two main regulators of aldosterone production. The amount of sodium present in the body affects the extracellular volume, which in turn influences blood pressure. Therefore, the effects of aldosterone in sodium retention are important for the regulation of blood pressure.


title: Adrenal gland

text: Cortisol is the main glucocorticoid in humans. In species that do not create cortisol, this role is played by corticosterone instead. Glucocorticoids have many effects on metabolism. As their name suggests, they increase the circulating level of glucose. This is the result of an increase in the mobilization of amino acids from protein and the stimulation of synthesis of glucose from these amino acids in the liver. In addition, they increase the levels of free fatty acids, which cells can use as an alternative to glucose to obtain energy. Glucocorticoids also have effects unrelated to the regulation of blood sugar levels, including the suppression of the immune system and a potent anti-inflammatory effect. Cortisol reduces the capacity of osteoblasts to produce new bone tissue and decreases the absorption of calcium in the gastrointestinal tract.


title: Adrenal gland

text: The adrenal gland secretes a basal level of cortisol but can also produce bursts of the hormone in response to adrenocorticotropic hormone (ACTH) from the anterior pituitary. Cortisol is not evenly released during the day – its concentrations in the blood are highest in the early morning and lowest in the evening as a result of the circadian rhythm of ACTH secretion. Cortisone is an inactive product of the action of the enzyme 11β-HSD on cortisol. The reaction catalyzed by 11β-HSD is reversible, which means that it can turn administered cortisone into cortisol, the biologically active hormone.


title: Adrenal gland

text: All corticosteroid hormones share cholesterol as a common precursor. Therefore, the first step in steroidogenesis is cholesterol uptake or synthesis. Cells that produce steroid hormones can acquire cholesterol through two paths. The main source is through dietary cholesterol transported via the blood as cholesterol esters within low density lipoproteins (LDL). LDL enters the cells through receptor-mediated endocytosis. The other source of cholesterol is synthesis in the cell's endoplasmic reticulum. Synthesis can compensate when LDL levels are abnormally low. In the lysosome, cholesterol esters are converted to free cholesterol, which is then used for steroidogenesis or stored in the cell.


title: Adrenal gland

text: The initial part of conversion of cholesterol into steroid hormones involves a number of enzymes of the cytochrome P450 family that are located in the inner membrane of mitochondria. Transport of cholesterol from the outer to the inner membrane is facilitated by steroidogenic acute regulatory protein and is the rate-limiting step of steroid synthesis.


title: Adrenal gland

text: The layers of the adrenal gland differ by function, with each layer having distinct enzymes that produce different hormones from a common precursor. The first enzymatic step in the production of all steroid hormones is cleavage of the cholesterol side chain, a reaction that forms pregnenolone as a product and is catalyzed by the enzyme P450scc, also known as "cholesterol desmolase". After the production of pregnenolone, specific enzymes of each cortical layer further modify it. Enzymes involved in this process include both mitochondrial and microsomal P450s and hydroxysteroid dehydrogenases. Usually a number of intermediate steps in which pregnenolone is modified several times are required to form the functional hormones. Enzymes that catalyze reactions in these metabolic pathways are involved in a number of endocrine diseases. For example, the most common form of congenital adrenal hyperplasia develops as a result of deficiency of 21-hydroxylase, an enzyme involved in an intermediate step of cortisol production.


title: Adrenal gland

text: Glucocorticoids are under the regulatory influence of the hypothalamus-pituitary-adrenal (HPA) axis. Glucocorticoid synthesis is stimulated by adrenocorticotropic hormone (ACTH), a hormone released into the bloodstream by the anterior pituitary. In turn, production of ACTH is stimulated by the presence of corticotropin-releasing hormone (CRH), which is released by neurons of the hypothalamus. ACTH acts on the adrenal cells first by increasing the levels of StAR within the cells, and then of all steroidogenic P450 enzymes. The HPA axis is an example of a negative feedback system, in which cortisol itself acts as a direct inhibitor of both CRH and ACTH synthesis. The HPA axis also interacts with the immune system through increased secretion of ACTH at the presence of certain molecules of the inflammatory response.


title: Adrenal gland

text: Mineralocorticoid secretion is regulated mainly by the renin–angiotensin–aldosterone system (RAAS), the concentration of potassium, and to a lesser extent the concentration of ACTH. Sensors of blood pressure in the juxtaglomerular apparatus of the kidneys release the enzyme renin into the blood, which starts a cascade of reactions that lead to formation of angiotensin II. Angiotensin receptors in cells of the zona glomerulosa recognize the substance, and upon binding they stimulate the release of aldosterone.


title: Adrenal gland

text: Cells in zona reticularis of the adrenal glands produce male sex hormones, or androgens, the most important of which is DHEA. In general, these hormones do not have an overall effect in the male body, and are converted to more potent androgens such as testosterone and DHT or to estrogens (female sex hormones) in the gonads, acting in this way as a metabolic intermediate.


title: Adrenal gland

text: Primarily referred to in the United States as epinephrine and norepinephrine, adrenaline and noradrenaline are catecholamines, water-soluble compounds that have a structure made of a catechol group and an amine group. The adrenal glands are responsible for most of the adrenaline that circulates in the body, but only for a small amount of circulating noradrenaline. These hormones are released by the adrenal medulla, which contains a dense network of blood vessels. Adrenaline and noradrenaline act by interacting with adrenoreceptors throughout the body, with effects that include an increase in blood pressure and heart rate. Actions of adrenaline and noradrenaline are responsible for the fight or flight response, characterised by a quickening of breathing and heart rate, an increase in blood pressure, and constriction of blood vessels in many parts of the body.