Aarushhh/wikipedia-simple-splitted huggingface dataset:
Robert Todd Lincoln, Secretary of War, son of former U.S. President Abraham Lincoln
 Joe Louis, world heavyweight boxing champion
 Allard Lowenstein, U.S. Congressman from New York.
 John R. Lynch, freedman, U.S. Army major, and Member of Congress
 Mike Mansfield, longest-serving Senate Majority Leader, United States Ambassador to Japan
 George C. Marshall, Chief of Staff of the Army, General of the Army, Emissary to China, Secretary of State, and Secretary of Defense. Instrumental in developing the Marshall Plan after World War II
 Lee Marvin, Marine Corps veteran and actor
 Bill Mauldin, editorial cartoonist; noted for World War II–era work satirizing military life in Stars and Stripes
 George B. McClellan, Jr. (1865–1940) Mayor of New York (1904–1909), son of Union Army Major General George B. McClellan
 John C. Metzler, World War II sergeant, former superintendent of Arlington National Cemetery (1951–1972)
 Daniel Patrick Moynihan, U.S. Senator from New York
Phelps Phelps, 38th Governor of American Samoa and United States Ambassador to the Dominican Republic
 Spot Poles, considered among the greatest outfielders of the Negro Leagues
 William Rehnquist, Chief Justice of the United States
 Earl W. Renfroe, orthodontist who helped originate the concept of preventive and interceptive orthodontics.
 Frank Reynolds, ABC television anchorman
 Samuel W. Small, journalist, evangelist, prohibitionist.
 Johnny Micheal Spann, CIA officer, first American killed in Afghanistan. Although Spann had served in the USMC, he was not in the military when killed. However, because he had received the CIA's Intelligence Star, considered the equivalent of the US Military's Silver Star and recognized as such by President George W. Bush, Spann was approved for burial in Arlington National Cemetery.
 Ted Stevens, US Senator from Alaska
 Samuel S. Stratton, 15-term U.S. Representative from New York
William Howard Taft, Secretary of War, President of the United States, Chief Justice of the United States
 George Westinghouse, Civil War veteran, Westinghouse Electric founder
 Harvey W. Wiley, first Commissioner of the Food and Drug Administration, "father" of the Pure Food and Drug Act
 Charles Willeford, World War II veteran and author
 William Christman First soldier to be buried at Arlington Cemetery
References

Further reading
 Poole, Robert M., On Hallowed Ground: The Story of Arlington National Cemetery , Walker & Co, 2009.

Other websites

 
 
 
 
 

1864 establishments in the United States
Military monuments and memorials in the United States
Commonwealth War Graves Commission
19th-century establishments in Virginia
1864 establishments
1864 in the United States
Burials at Arlington National Cemetery
History of Virginia
National Register of Historic Places
United States Army
Buildings and structures in Washington, D.C.
In organic chemistry, torquoselectivity describes electrocyclic reactions that produce one isomer more than the other. An official definition is "the preference for inward or outward rotation of substituents in conrotatory
or disrotatory electrocyclic reactions." In other words, a chemical reaction is torquoselective if the groups of atoms that hang from a ring of atoms are more likely to have rotated in a particular direction during the reaction (instead of being equally likely to rotate in both possible directions.) Torquoselectivity is different from the normal diastereoselectivity of pericyclic reactions. Instead it is more selectivity beyond the Woodward–Hoffmann rules. The name comes from the idea that the substituents in an electrocyclization appear to rotate during the reaction. The reaction produces a single product because only one direction of rotation was allowed (that is, the direction of rotation on the substituents was favored). The concept was originally developed by Kendall N. Houk.
When a chemical reaction closes a ring, its torquoselectivity is the same as enantioselectivity. A single enantiomer of a cyclization product is formed from the selective ring closure of the starting material. In a typical electrocyclic ring closing, selection for either conrotatory or disrotatory reactions modes still produces two enantiomers. Torquoselectivity is a discrimination between these possible enantiomers that requires asymmetric induction.

Torquoselectivity also happens in selective electrocyclic reactions that break open rings. The different directions of rotation produce distinct structural isomers. In these cases, steric strain is often the driving force for the selectivity. Studies have shown that the selectivity can also be changed by the presence of electron donating and electron withdrawing groups.
Torquoselectivity can also apply to other mechanisms, including chiral Lewis acid catalysts, induction by neighboring stereocenters (in which case the torquoselectivity is a case of diastereoselectivity), and axial-to-tetrahedral chirality transfer. An example of axial-to-tetrahedral chirality transfer is shown below for the torquoselective Nazarov cyclization reaction of a chiral allenyl vinyl ketone.

References

Stereochemistry
The 16th Pan American Games were held in 2011 in Guadalajara, Mexico. Over 6,000 athletes from 42 countries competed in 36 sports.

References

Pan American Games
Captain Kidd, or, by his real name, William Kidd, ( 1645 – 23 May 1701) was a Scottish pirate and sailor. It is heard that he buried a treasure chest on a deserted island. The chest had a lot of gold and jewels in it. He was found guilty of murder and was executed by hanging at 'Execution Dock', Wapping, in London on 23 May 1701.

References 

Scottish criminals
People executed by hanging
Pirates
1645 births
1701 deaths
A gripper is something that grips things or makes it easier to grip things. It may refer to:

 Grippers, tools for exercising the muscles in a person's hand
 Robot end effector, the "hand" of a robot
 Grip (job), a job in filmmaking
 Shoes that have cleats, which make it easier to grip the ground
Jeffrey Franklin Kent (born March 7, 1968) was an American baseball player. He played second base. He played for six different teams, including the New York Mets, San Francisco Giants, and Los Angeles Dodgers. He was a five-time All-Star, and the 2000 National League MVP. In his career, he batted .290, with 2,461 hits, 377 home runs and 1,518 RBIs.  He has more home runs than any other second baseman.  He also drove in 90 or more batters in nine straight seasons.

Kent was from Bellflower, California and went to high school in Huntington Beach.

Other websites

1968 births
Baseball players from California
Cleveland Indians players
Houston Astros players
Living people
Los Angeles Dodgers players
National League All-Stars
New York Mets players
San Francisco Giants players
Toronto Blue Jays players
An angelshark is a species of cartilaginous fish in the genus Squatina. They have flattened bodies and wide pectoral fins, which make them look similar to rays. Twenty-three species are known. 

The genus is the only one in its family, Squatinidae, and order Squatiniformes. They are worldwide in temperate and tropical seas.  Most species are in shallow temperate or tropical seas, but one species is found in deeper water, down to 1,300 metres.  Angelsharks are specialised for a kind of predation which is unusual for sharks.
They are ambush predators. They have extensible jaws with long, needle-like teeth. They quickly snap upwards to capture prey. They bury themselves in sand or mud lying in wait for their prey, which includes fish, crustaceans, and many different types of mollusks.
Discription and biology
The front part of the angel sharks' bodies are wide and flattened, but the back part is more muscular. The eyes and spiracles are on the top, and the five gill slits are on its back. Both the pectoral fins and the pelvic fins are large and are held horizontally. There are two dorsal fins, no anal fin. Unusually for sharks, the lower lobe of the caudal fin is longer than the upper lobe. Most types of angel sharks grow to a length of about 1.5 metres: the Japanese angelshark reaches two metres. They are ovoviviparous, and can have up to 13 pups at a time.

Behavior
Although angelsharks are bottom dwellers and appear harmless, they can give painful bites if provoked, due to their powerful jaws and sharp teeth. Angelsharks may bite if a diver approaches the head or grabs the tail. 

thumb|right|200px|An Australian angelshark

References

Cartilaginous fish
The goblin shark (Mitsukurina owstoni) is a rare, poorly-known species of deep-sea shark. Sometimes called a "living fossil", it is the only living species in the family Mitsukurinidae.

The Goblin shark can be easily identified by its long, flattened snout. Males can reach up to lengths of 12.6 feet (3.8 meters), and females can reach up to lengths of 12.2 feet (3.7 meters). The heaviest Goblin shark found weighed 210 kg (460 pounds).

The Goblin shark is a bottom-dwelling shark, being found in waters as deep as 4265 feet (1,300 meters). It has been found in the Atlantic, Indian, and Pacific Ocean.
Description
The Goblin shark can be easily identified by its long, flattened snout. It has a noticeably long head, tiny eyes and five short gill openings. The mouth is large and parabolic in shape. Its body is soft and flabby. This shark has a long caudal fin without a ventral lobe. The pectoral fins are short and wide, and the two dorsal fins are small, round and equal in size. The anal fin is round and smaller than the dorsal fins, while the pelvic fins are larger than the dorsals. The Goblin shark has a long extendable jaw, with long, thin teeth. The shape of its body shows that the Goblin shark is a slow moving species of shark.
Living Goblin sharks are a pinkish-white color with bluish fins. Specimens fade and become a brownish color when preserved in alcohol.
Goblin sharks have 26 long, thin, spike-like teeth on their upper jaw and 24 on their lower jaw. They have three rows of front teeth on each side of both jaws. The teeth in the front upper jaw are separated from the smaller upper side teeth by a gap.
Mature male Goblin sharks have been found to reach lengths ranching from 8.66 to 12.6 feet (2.6 to 3.8 meters) long. Mature females have been found to reach lengths ranging from 11 to 12.2 feet (3.4 to 3.7 meters). The size at birth is not known, but the smallest specimen found was 3.51 feet (1.07 meters) long. The heaviest Goblin shark found weighed 210 kg (460 pounds), and was 3.8 metres (12 feet) long.
Distribution
This species of deep-sea shark is thought to be widely distributed. Specimens have been seen in the Atlantic, off the coast of Guyana, Surinam, French Guiana, France, Madeira, Senegal, Portugal, and the Gulf of Guinea. It has also been reported in the western Pacific off Japan, Australia and New Zealand. In the Indian Ocean it is found off South Africa and Mozambique. It was recently recorded in the U.S.A near San Clemente Island off the coast of California, as well as in the northern Gulf of Mexico, south of Pascagoula, Mississippi.
Habitat
The Goblin shark is a bottom-dwelling shark that is rarely seen at the surface or in shallow coastal waters. This species is found along the outer continental shelves, upper slopes, and off seamounts. Most specimens have been observed near continental slopes, between 885 and 3149 feet (270 and 960 meters) deep. It has been found in waters up to 4265 feet (1,300 meters) deep, and in waters as shallow as 311 to 449 feet (95 to 137 meters). Records show that the Goblin shark could also be an oceanic species.
Feeding
The Goblin shark senses its prey with the help of electro-sensitive organs. The jaws are made for rapid projection to help in the capture of prey. The jaw is thrust forward by a double set of ligaments at the mandibular (lower jaw) joints. When the jaws are withdrawn, the ligaments are stretched and they become relaxed when the jaw is projected forward. The jaws are usually held tightly while swimming, and have a function like a catapult when the Goblin shark wants to feed. The front teeth are made for crushing. The Goblin shark feeds on shrimps, pelagic octopuses, fish, and squids. It is also thought to feed on crabs, and deep-sea rockfish.
Reproduction
There is no proper information about the reproduction habits of the Goblin shark. No pregnant female has been found or captured. It is believed that they are ovoviviparous, meaning that the young are born live, but there is no placental connection, instead the embryos are nourished by egg yolk. There is no real information of when the Goblin shark matures, when and how it mates, and how long the gestation period lasts.

Human interactions
The Goblin shark is fished commercially off Japan, and is sometimes caught along with cutlassfish off Portugal. Elsewhere, they are taken mainly as bycatch of deep-water trawls and occasionally with deep-water longlines, deep-set gillnets, and possibly purse seines.

The Goblin shark is probably harmless, but since it has rarely been encountered by humans it is not yet possible to tell. Although probably common, this species of shark is rarely seen and is therefore poorly known.

References 

Sharks
The blue shark (Prionace glauca) is a species of requiem shark. It has a slim, smooth-looking body with large eyes, and a long, cone-shaped snout. The dorsal surface is a dark blue colour, and the belly is white.

The largest blue sharks can reach lengths of up to 3.8 metres, and weigh as much as 206 kg. The shark is found worldwide in temperate and tropical waters. They range from the surface to as deep as 350 metres, and prefer water with the temperature of 7 to 16 °C.

Description
Description

The blue shark has a slim, smooth-looking body with large eyes, and a long, cone-shaped snout that is longer than the width of its mouth. It has extremely long, pointed pectoral fins. The dorsal fin is moderate in size. It is closer to the pelvic fins than to the pectoral fins. The blue shark's name comes from its distinct dark blue dorsal surface, and bright blue sides. The belly is white. The colours of the blue shark help it to camouflage in the open ocean. The largest blue shark on record measured 3.8 metres (12.5 feet), but they are rumored to get as large as 6.1 metres (20 feet). Males reach maturity at the ages of 4–5 years, when they are at the lengths of between 1.8-2.8 metres (6-9.2 feet). Females mature at slightly older ages from 5–6 years, when they are at the lengths of between 2.2-3.2 metres (7.2-10.5 feet). The largest blue sharks range in weights from 204–206 kg (450-454 pounds).
Habitat
Blue sharks are found worldwide, in temperate and tropical waters. They are a pelagic species that rarely comes near shore. They have been known to frequently swim to inshore areas around oceanic islands, and locations where the continental shelf is narrow. In the western Atlantic they can be found from Newfoundland, Canada to Argentina. In the eastern Atlantic they range from Norway to South Africa, including the Mediterranean. In the Indian Ocean, they range from South Africa to Indonesia. In the western Pacific they are found from Japan to New Zealand. In the eastern Pacific, Blue sharks range from the Gulf of Alaska to Chile.
Being a pelagic species, the shark's habitat consists of open ocean areas, from the surface to 350 metres (1,148 feet) in depth. They prefer cooler water ranging from 7 to 16 °C (45-61 °F) in temperature. They are known to swim in water with the temperature of 21 °C (70 °F) or greater. When in the tropics, the shark usually swims to deeper water with cooler temperatures. This is common in the tropical Indian Ocean, where the majority of Blue sharks are found at depths of 80–220 metres (263–722 feet), where water temperatures range from 12-25 °C (54-77 °F). In the Pacific, at latitudes between 20°N and 50°N, they are known to migrate to higher latitudes during the summer and lower latitudes during the winter. Their populations remain constant throughout the year between 20°N and 20°S latitude.

Behaviour
Behaviour

The blue shark has one of the largest ranges in terms of depths of the water. They can be found from the surface to the bottom. This type of adaption makes it easy for them to be able to find food. Blue sharks are known to migrate thousands of miles for food and for mating. This species of shark often is not found alone. Instead, they form groups based on their gender and on their size. They are often referred to as the "Wolves of the Sea" due to the complex levels of hierarchy that they form within their groups which highly reflects the behaviour of wolves. Due to their territorial instincts and their aggressive behaviours, divers have to be very careful around them. Many of the filmings of these sharks have been done with the divers in cages for the divers' own personal safety.
Feeding
The majority of the blue shark's diet consists of invertebrates such as squid, cuttlefish, and pelagic octopus, and bony fish such as herring and sardines. They also feed on various types of sea birds, crustaceans such as lobster, crab, and shrimp, and they also feed on carrion.

They are very opportunistic when it comes to hunting. They have been known to feed on almost anything that they can find, including prey items which they can find in large numbers such as shrimp. They have been known to feed until they actually can not eat any more. Since they feed on almost anything that they can find, they have been known to feed on garbage and rubbish such as plastic and rubber tires. This can result in the shark falling ill, and even dying.
Reproduction
Blue sharks are viviparous, with the males maturing at the age of 4-5, and females reaching maturity at the age of 5-6. The gestation period lasts from 9 to 12 months. During mating, the males have been known to bite the females, but their thick skin is believed to stop any pain. Pups are 41 to 50 cm (16 to 20 inches) long at birth, with females giving birth to 4-135 pups at a time, but the number of pups depend on the size of the female, with larger females giving birth to more pups. Blue sharks live to up to 20 years.

Predators
Predators of the blue shark include the California sea lion and larger sharks such as the shortfin mako shark, and the great white shark.
Human interaction
Recreationally, blue sharks are considered a sport fish, and large individuals provide a challenge for fishermen. Most commercially caught blue sharks are considered bycatch.  It is estimated that 10 to 20 million are killed each year, possibly having a negative impact on world populations. The salmon, mackerel, and sardine fisheries are affected by Blue shark predation on catches, and entanglement in nets. The fins of blue sharks are sold to Asian markets and are used to make shark-fin soup.
Conservation
Although blue sharks are among the most abundant, widespread, and fast growing shark, they are one of the most heavily fished sharks in the world. With an estimated 10 to 20 million individuals caught and killed each year, there is concern not only about what this is doing to Blue shark populations, but also about the effect the removal of such an important predator might have on the oceanic ecosystem. Blue sharks are one of the most important species in the international shark-fin trade. However, their meat, while eaten in a few countries, is not very popular. The blue shark is listed as Near Threatened by the IUCN.

References

Other websites

 
 
 
 ARKive - Images and movies of the blue shark (Prionace glauca) 
 Canadian Shark research laboratory 
 BBCNews - 'Jaws' comes to a US beach 3 August 2010.
 BBCNews - Footage of shark which closed New Quay (Wales) beach 8 August 2012.

Sharks
"Let's Kill Hitler" is the eighth episode of the sixth series of the British science fiction television series Doctor Who. The episode was broadcast on BBC One, Space and BBC America on 27 August 2011. It is the second episode of a two-part story. The story began with "A Good Man Goes To War" (episode seven). It is the 778th episode. 

The episode centers around River Song and the history of Amy Pond. 

Doctor Who
2011 television episodes
British television episodes
Romano Mattè (Trento, January 17 1939) is an Italian former association football player, who coached the national teams of Mali and Indonesia.

Italian footballers
People from Trento
1939 births
Living people
Mental breakdown (also known as a nervous breakdown) is a non-medical term used to describe an acute, temporary, short phase of a disorder with features of depression or anxiety.

Definition
The terms 'nervous breakdown' and 'mental breakdown' are not formally defined in a diagnostic system such as the DSM-IV or ICD-10. The terms are not often used in the scientific literature on mental illness.

Specific cases are sometimes described as a 'breakdown' only after a person cannot function in day-to-day life. It is a temporary condition.
Causes
Different things can cause a mental breakdown. A study found that problems with intimate relationships, such as divorce or separation, contributed to 24% of nervous breakdowns. Problems at work and school accounted for 17% of cases, and financial problems for 11%. Surveys suggest that in the United States, health problems have decreased in importance as a contributor to nervous breakdowns, as these accounted for 28% of nervous breakdowns in 1957, 12% in 1976, and only 5.6% in 1996.

In themselves, nervous breakdowns are considered a 'health problem' by most professionals.

References 

Mental illnesses
Javier Hernández Balcázar  (born June 1, 1988 in Guadalajara, Mexico), also known as Chicharito, is a Mexican footballer. He plays for the American club, LA Galaxy and the Mexican national team.

Biography
Hernández was born in 1988 in Guadalajara, Mexico. His father Javier Hernández Gutiérrez is a retired footballer.

Honours
Guadalajara
Mexican Primera División: Apertura 2006

Manchester United
Premier League: 2010–11, 2012–13
FA Community Shield: 2010

Real Madrid
FIFA Club World Cup: 2014

Mexico
CONCACAF Gold Cup: 2011
CONCACAF Cup: 2015

Individual
Mexican Primera División Balón de Oro – Best Striker: Bicentenario 2010
Sir Matt Busby Player of the Year: 2010–11
CONCACAF Gold Cup Golden Boot: 2011
CONCACAF Gold Cup MVP: 2011
IFFHS Most Popular Player of the CONCACAF: 2011
Bundesliga Player of the Month: November 2015, December 2015, January 2016, September 2016, February 2017
Bundesliga Idol: 2015
Bundesliga Team of the Season: 2015–16
CONCACAF Player of the Year: 2015

Career statistics

Club
Club

1Includes the InterLiga, FA Cup and DFB-Pokal.
2Includes the Copa Libertadores, Copa Sudamericana, North American SuperLiga, UEFA Champions League and the UEFA Europa League.
3Includes other competitive competitions, including the Primera División playoffs, FA Community Shield, UEFA Super Cup and the FIFA Club World Cup.

International

References

1988 births
Living people
Mexican footballers
A booster seat is a seat cushion that is used to elevate children in cars. Children have to use booster seats so that the seat belt fits better. 
In general most booster seats can be used for children who are between four and twelve years of age and between 40 and 59 inches (100–150 cm) tall. Children under 40 inches are usually too small to use booster seats and have to use a car seat (a child safety seat with an own seat belt system, used for children under the age of 4-6).
Many countries have laws that require the use of booster seats. In the United States of America children  under 57 inches (145 cm) and younger than 9 years old have to use a booster seat. Many European countries require a booster seat until the child is either twelve years old or 59 inches tall. There are some exceptions. In the United Kingdom for example children are allowed to ride without a booster seat when they are 53 inches tall and in Austria children who are not 59 inches tall have to use a booster seat until their 14th birthday. However booster seats are used to keep children safe, not because of a law. In general no child can ride safely in a car without booster seat when he is not 57 inches tall. It is proved that children under 57 inches who do not use a booster seat are more likely to suffer serious injuries or even death in the event of an accident.
References

Child safety
Arthur Rubinstein (January 28, 1887 – December 20, 1982) was a Polish-American pianist. He received praise from around the world for his playing of the music of a selection of composers (many call him the greatest Chopin player of the century).

Rubinstein was born in Łódź, Poland to a family of Jews. He was the youngest child of the family. His father was a rich owner of a factory.

Although his given name is Artur Rubinstein, in English-speaking countries he wanted to be known as Arthur Rubinstein. However, his United States impresario Sol Hurok wanted him to still be billed as Artur, and his recordings were released in the West under both names.

Rubinstein learned the piano at the age of two in Warsaw, before beginning study in Berlin at the age of eight. His debut in Berlin was made in 1898 followed by a debut at Carnegie Hall in the United States in 1906.
Throughout his life, Rubinstein was famous as a solo pianist, a soloist in piano concertos, and even as a chamber musician. He retired from the stage at age eighty-nine, and died in Geneva, Switzerland, on 20 December 1982, at the age of ninety-five, and his body was cremated. On the first anniversary of his death, his ashes were buried in Jerusalem – as specified in his will – in a plot now nicknamed the "Rubinstein Forest" overlooking the Jerusalem Forest.

References

Other websites 

 

1887 births
1982 deaths
American pianists
Jewish American musicians
Polish pianists
People from Łódź
The United States Department of Defense employs civilian firefighters. They are stationed at military bases to work as firefighters. These workers have their own uniforms and equipment. They are not a part of any military unit. They will work alongside military units if needed. Many times, they are the only firefighters at a military facility. The civilian firefighters wear special uniforms, usually a dark blue suit with a badge and with a shoulder patch indicating their firefighting organization.

Firefighters go to special classes to learn firefighting skills. They earn certificates after taking the classes. One major class is called "DoD Fire & Emergency Services Training."

Related pages
 Firefighting

References
References

Other websites
 Military Firefighter Heritage Foundation  website.  
 U.S. Defense Dept. Fire & Emergency Services Certification Program  web page.
 dodfire.com, Organization website
 History web page, dodfire.com 
 Website for US Army civilian firefighter units , U.S. Army Installation Management Command 
 fedfire.org, federal firefighters group in California. 
 Fort Knox firefighters  website
 Fort Knox firefighters patch  website
 US Government document authorizing use of uniforms for civilian firefighters

United States Department of Defense
Firefighting
The bongo (Tragelaphus eurycerus) is a nocturnal antelope. It has two subspecies: the western or lowland bongo, and the eastern or mountain bongo. The western bongo is near threatened and the mountain bongo is critically endangered. Bongos eat plants. They live in forests in Africa. Kenya is the only place eastern bongos live in the wild. Like the west African giraffe, the eastern or mountain bongo is one of the most threatened animals in Africa. Bongos live in both captivity and the wild.

As bongos grow their horns appear. Both male and female bongos have horns.

References

Bovines
Mammals of Africa
A dyotropic reaction is a type of chemical reaction. It is when an organic compound changes its structure. Two substituents jump from one place on the molecule to another. It is a pericyclic valence isomerization when two sigma bonds move at the same time to a new place on the same molecule. Dyotropic reactions are important in organic chemistry. They can explain how certain reactions work. Dyotropic reactions can be a useful step in making large and complicated molecules. Dyotropic reactions were first described by Manfred T. Reetz in 1971. The name "dyotropic reaction" comes from the Greek word dyo meaning "two." "Rearrangement" means that the reaction changes the bonds between atoms on a single molecule.

In a type I reaction, two migrating groups trade their relative positions. A type II reaction   involves migration to new bonding sites without positional interchange.
Type I rearrangements
In type I rearrangements (Y-A-B-X conversion to X-A-B-Y), the two migrating groups are oriented trans to each other. The reaction leaves both groups on the opposite sides. The first example of a dyotropic rearrangement involving a carbon-carbon bond was reported by Cyril A. Grob and Saul Winstein. They saw the exchange of two bromine atoms in a certain steroid. 

In a simple example, the two bromine atoms in 3-tert-butyl-trans-1,2-dibromohexane mutarotate by heating. In the transition state both bromine atoms connect symmetrically two both carbon atoms on opposite sides and the reaction is concerted. Chemists have also investigated stepwise mechanisms in dyotropic reactions.
In organic synthesis, an important dyotropic reaction is the conversion of 4-substituted-gamma-lactones to butyrolactones. Type I dyotropic rearrangements also occur around carbon-oxygen bonds. One example is using heat to change RRSi1R3C-O-Si2R3 to RRSi2R3C-O-Si1R3.  (This reaction can go in both directions depending on temperature.) Another example is the 1,2-Wittig rearrangement. Dyotropic reactions can also happen with N-O bonds or N-N bonds.

Type II rearrangements
Type II rearrangements often involve two hydrogen atoms moving along a carbon skeleton. This reaction type can be found in certain transfer hydrogenations. An example is hydrogen transfer in syn-sesquinorbornene
disulfones.

References

Organic reactions
The Diels–Alder reaction (DA) is a chemical reaction between organic compounds. The reaction causes the compounds to form a new six-sided compound. This is called a cyclohexene. A conjugated diene joins with an alkene to make the cyclohexene. This compound looks like a ring.

This reaction was discovered by Otto Diels and Kurt Alder in 1928. In 1950, they were given the Nobel Prize in Chemistry for their work on this reaction. The DA reaction is very useful as it means cyclohexenes can be made with very little energy. Cyclohexenes are used to make complex organic molecules. One of the first uses of the DA reaction was to make insecticides.
The DA reaction makes a new hexagonal ring-shaped compound. A compound with two double bonds which are one carbon atom apart from each other is joined to another compound with at least one double bond. A DA reaction can also happen if some of the atoms in the newly formed ring are not carbon. Some of the DA reactions are reversible. The reaction caused during this breaking up of the cyclic system is called the retro-Diels–Alder. These retro-Diels–Alder compounds are often seen when they are analyzed by mass spectrometry.

Some chemists call the Diels–Alder reaction the 'Mona Lisa' of organic reactions. Like the simple smile on the painting, the reaction may be far more complex than chemists have so far discovered.

Lewis acids (AlCl3, ZnCl2, and others) act as catalysts to the reaction.

References

Other websites
 Asymmetric Hetero-Diels–Alder Reactions
 Semi-empirical calculations of the Diels–Alder reaction.
 Endo Addition Rule 

Organic reactions
Dagestan is a federal subject of the Russian Federation in the Caucasus region. The name comes from two combined Turkic and Persian words, dag which means mountain in the Turkic languages, and stan which means land in the Persian language. Therefore, the literal translation of Dagestan is Land of the Mountains. Dagestan has a population of nearly 3 million, and its people are known as Dagestani. Its capital city is Makhachkala.
People 
Dagestan has the status of "republic" in Russia and has its own constitution and official languages. Republics in Russia are the home of its ethnic minorities (those who are not Russians), and usually one or two nationalities have a majority of the population in each republic. But in Dagestan, there are over 30 different nationalities (the largest of which are the Avar, Lak, Dargwa, Lezgian, and Tabasaran), and none of these form a majority. This is because the mountains in the region make it hard for people to move around. These people speak 30 different languages, but use Russian as their lingua franca to communicate between each other.

Most people of Dagestan are Muslims and belong to the Shafi`i school of Sunni Islam.

Famous people 
 Rasul Gamzatov
 Imam Shamil
 Shaykh Said afandi al-Chirkawi
 Khabib Abdulmanapovich Nurmagomedov
 Islam Ramazanovich Makhachev

Sources 
 Islam in Dagestan
 Official website of Dagestani government

References
Theoretical chemistry tries to explain data from chemistry experiments. It uses mathematics and computational analysis. Theoretical chemistry predicts what happens when atoms combine to form molecules. It also predicts chemical properties (characteristics) of molecules. An important part of theoretical chemistry is quantum chemistry.

More reading 
 Attila Szabo and Neil S. Ostlund, Modern Quantum Chemistry: Introduction to Advanced Electronic Structure Theory, Dover Publications; New Ed edition (1996) , 
 Robert G. Parr and Weitao Yang, Density-Functional Theory of Atoms and Molecules, Oxford Science Publications; first published in 1989; , 

 
Branches of chemistry
A pebble is a piece of rock with a particle size of 4 to 64 millimetres. They are often made of flint.

Pebbles are larger than granules (2 to 4 millimetres diameter) and smaller than cobbles (64 to 256 millimetres diameter). A rock made predominantly of pebbles is termed a conglomerate. Pebble tools are among the earliest known man-made artifacts, dating from the Palaeolithic period of human history.

A beach composed chiefly of surface pebbles is commonly termed a shingle beach. This type of beach resists wave erosion, and has ecological niches which can provide habitat for animals and plants.

Sedimentary rocks
MESSENGER, MErcury Surface, Space ENvironment, GEochemistry and Ranging, was an unmanned NASA and APL spacecraft. It was orbiting and studying the planet Mercury.  Its mission lasted 10 years, 8 months and 28 days.

It was launched on August 3, 2004 at Cape Canaveral Air Force Station. It was aboard a Boeing Delta II rocket. After launch, the probe did several fly-bys and deep space manoeuvres to gain the right trajectory and speed. 

It completed 30% mapping of Mercury on January 14, 2008. MESSENGER made one more pass by Mercury in 2009, and on March 18, 2011 began to orbit Mercury. 100% mapping was completed in March 2013 and the probe continued its studies. On April 30, 2015, it crashed into Mercury. It crashed near the crater Janáček.

References

NASA spacecraft
Spacecrafts launched in 2000s
Mercury (planet)
In psychology, compensation is a way people hide something that they cannot do well, by doing something else really well. They may not even be aware that they are doing it. Compensation can hide real or imagined problems and personal or physical inferiority. However it does not really solve the cause of the problem. Positive compensations may help a person overcome difficulties. But negative compensations do not, and can even make the problems worse.
 
There are two kinds of negative compensation:
Overcompensation, where a person has a goal to gain superiority. This leads to wanting power, dominance, self-esteem and self-devaluation.
Under compensation which includes a demand for help, leads to a lack of courage and a fear for life.

A well-known example of failing overcompensation, can be seen in people going through a mid life crisis. Approaching midlife many people (especially men) lack the energy to maintain their psychological defenses, including their compensatory acts.
Origin
Alfred Adler, founder of individual psychology, used the word compensation in relation inferiority feelings. In his book Study of Organ Inferiority and Its Physical Compensation (1907) he wrote if a person feels inferior (weak) then they will (usually) try to compensate for it somewhere else.

Adler's reason to explore this was from his own experience. He was shy and yet he pushed himself to give lectures.

Adler also "transferred" this idea of compensation to psychic training.

Cultural implications
Narcissistic people, by compensation theory, hide their feelings of low self-esteem by:
 talking "highly"
 contacting "highly admired" persons

Narcissistic children try to compensate for their jealousy and anger by fantasizing about:
 power
 beauty
 wealth
Christopher Lasch, an American historian and social critic wrote in his book The Culture of Narcissism (1979) that North American society in the 1970s was narcissistic. The narcissistic society:
 worships consumption
 fears dependency, aging, and death. 
Therefore, it is "fascinated" with fame.

Consumption can be an example of compensation (see study by Allison J. Pugh: From compensation to ‘childhood wonder’). Examples:
 use of goods to convey human relationships. 
 parents make up for "bad" conditions (poverty, abuse ...) they lived in
 parents make up for "bad" conditions (divorce, ...) they caused to children

References
 Claude S. Fisher: Comment On “Anxiety”: Compensation In Social History 
 Christopher Lasch (1979). The Culture of Narcissism: American Life in an Age of Diminishing Expectations. New York: Norton.
 Allison J. Pugh: ‘From compensation to ‘childhood wonder’: Why parents buy. 
 http://www.infinityinst.com/articles/alfred_adler.htm
 http://everything2.com/index.pl?node_id=535671
A shingle beach (or pebble beach) is a beach made of pebbles, not sand. The stones may be from  diameter. These beaches strongly resist erosion by waves.

This beach landform is quite common in Western Europe, because the pebbles come from the lines of flint in the chalk. Chesil Bank is an example. When the chalk erodes, the tough flint stays as pebbles.

Other examples are found in Bahrain, North America and in a number of other places. On the east coast of New Zealand's South Island, there are mixed shingle and sand fans in the braided rivers.

References
Puddingstone is a kind of sedimentary rock. It is formed when pebbles, perhaps from a shingle beach, are cemented together by silica coming out of solution.

The rock which forms is extremely hard and resistant to wear. It is used for grindstones and building. The pebbles are usually made of flint, and both they and the matrix are made of silica.

Sedimentary rocks
An eponym is a person's name that is used to name something else. This is common in some fields of knowledge.

References 

Names
In mathematics, a injective function is a function f : A → B with the following property. For every element b in the codomain B, there is at most one element a in the domain A such that f(a)=b, or equivalently, distinct elements in the domain map to distinct elements in the codomain.

The term injection and the related terms surjection and bijection were introduced by Nicholas Bourbaki. In the 1930s, he and a group of other mathematicians published a series of books on modern advanced mathematics.

An injective function is often called a 1-1 (read "one-to-one") function. However, this is to be distinguished from a 1-1 correspondence, which is a bijective function (both injective and surjective).

Basic properties
Formally:
  is an injective function if     or equivalently
  is an injective function if  
The element  is called a pre-image of the element  if  . Injections have one or none pre-images for every element b in B.
Cardinality
Cardinality is the number of elements in a set. The cardinality of A={X,Y,Z,W} is 4. This is written as #A=4.

If the cardinality of the codomain is less than the cardinality of the domain, then the function cannot be an injection. For example, there is no injection from 6 elements to 5 elements, since it is impossible to map 6 elements to 5 elements without a duplicate.

Examples

Elementary functions
Let f(x):ℝ→ℝ be a real-valued function y=f(x) of a real-valued argument x. (This means both the input and output are real numbers.)
Graphic meaning: The function f is an injection if every horizontal line intersects the graph of f in at most one point.
Algebraic meaning: The function f is an injection if f(xo)=f(x1) means xo=x1.
Example: The linear function of a slanted line is 1-1. That is, y=ax+b where a≠0 is an injection. (It is also a surjection and thus a bijection.)
Proof: Let xo and x1 be real numbers. Suppose the line maps these two x-values to the same y-value.  This means a·xo+b=a·x1+b. Subtract b from both sides. We get a·xo=a·x1. Now divide both sides by a (remember a≠0).  We get xo=x1. So we have proved the formal definition and the function y=ax+b where a≠0 is an injection.
 
Example: The polynomial function of third degree: f(x)=x3 is an injection. However, the polynomial function of third degree: f(x)=x3 –3x is not an injection.
Discussion 1: Any horizontal line intersects the graph of f(x)=x3 exactly once. (Also, it is a surjection.)
Discussion 2. Any horizontal line between y=-2 and y=2 intersects the graph in three points so this function is not an injection. (However, it is a surjection.)
Example: The quadratic function f(x) = x2 is not an injection. 
Discussion: Any horizontal line y=c where c>0 intersects the graph in two points. So this function is not an injection. (Also, it is not a surjection.)

Note: One can make a non-injective function into an injective function by eliminating part of the domain. We call this restricting the domain. For example, restrict the domain of f(x)=x² to non-negative numbers (positive numbers and zero). Define 
  where  
This function is now an injection. (See also restriction of a function.)

Example: The exponential function f(x) = 10x is an injection. (However, it is not a surjection.)
Discussion: Any horizontal line intersects the graph in at most one point. The horizontal lines y=c where c>0 cut it in exactly one point. The horizontal lines y=c where c≤0 do not cut the graph at any point.

Note: The fact that an exponential function is injective can be used in calculations. 
   
Example:

Other examples
Other examples 

Example: The logarithmic function base 10  f(x):(0,+∞)→ℝ defined by f(x)=log(x) or y=log10(x) is an injection (and a surjection). (This is the inverse function of 10x.)

Example: The function f:ℕ→ℕ that maps every natural number n to 2n is an injection. Every even number has exactly one pre-image. Every odd number has no pre-image.

Related pages
Function (mathematics)
Surjective function
Bijective function

References

Other websites
  interactive quiz
  interactive

Functions and mappings
Algebra
Lorient is a commune and seaport in the Morbihan department in Brittany.

Sister cities
Lorient is twinned with:
  Galway City, Ireland, since 1978
  Vigo, Spain
  Wirral, United Kingdom
  Ventspils, Latvia
  Ludwigshafen, Germany
  České Budějovice, Czech Republic
  Denizli, Turkey

Communes in Morbihan
Subprefectures in France
Bongo may mean:

In nature:
Bongo (antelope), a species of forest antelope from Africa

In geography:
Bongo Country, the name of several places in Africa
Bongo (Grand-Bassam), Ivory Coast

In entertainment:
Bongo drum, a percussion instrument made up of two small drums attached to each other
The Bongos, an America pop music band
Music Man Bongo, a model of bass guitar
DK Bongos, a video game controller

In vehicles:
Kia Bongo, an automobile
Mazda Bongo, a van

In fiction:
Bongo Comics, a comic book publishing company
Bongo (Dragon Ball) or Krillin, a character in Dragon Ball media

In other uses:
Bongo people (Gabon), a forest people
Bongo people (Sudan), an ethnic group in Sudan
Bongo language, their language, of the Bongo-Baka branch of Central Sudanic languages

People with the family name
Omar Bongo (1935–2009), former president of Gabon
Ali Bongo (1929–2009), British comedy magician
Ali Bongo Ondimba (born 1959), Current president of Gabon and son of Omar Bongo
In mathematics, a surjective or onto function is a  function f : A → B with the following property. For every element b in the codomain B, there is at least one element a in the domain A such that f(a)=b. This means that no element in the codomain is unmapped, and that the range and codomain of f are the same set.

The term surjection and the related terms injection and bijection were introduced by the group of mathematicians that called itself Nicholas Bourbaki. In the 1930s, this group of mathematicians published a series of books on modern advanced mathematics. The French prefix sur means above or onto and was chosen since a surjective function maps its domain on to its codomain.

Basic properties
Formally:
  is a surjective function if   such that 
where the element  is called the image of the element , and the element  a pre-image of the element .
The formal definition can also be interpreted in two ways: 
Every element of the codomain B is the image of at least one element in the domain A.
Every element of the codomain B has at least one pre-image in the domain A.
A pre-image does not have to be unique. In the top image, both {X} and {Y} are pre-images of the element {1}. It is only important that there be at least one pre-image.

Examples

Elementary functions
Let f(x):ℝ→ℝ be a real-valued function y=f(x) of a real-valued argument x. (This means both the input and output are numbers.)
Graphic meaning: The function f is a surjection if every horizontal line intersects the graph of f in at least one point.
Analytic meaning: The function f is a surjection if for every real number yo we can find at least one real number xo such that yo=f(xo). 
Finding a pre-image xo for a given yo is equivalent to either question:

 Does the equation f(x)-yo=0 have a solution? or
 Does the function f(x)-yo have a root?
In mathematics, we can find exact (analytic) roots only of polynomials of first, second (and third) degree. We find roots of all other functions  approximately (numerically). This means a formal proof of surjectivity is rarely direct. So the discussions below are informal.
Example: The linear function of a slanted line is onto. That is, y=ax+b where a≠0 is a surjection. (It is also an injection and thus a bijection.)
Proof: Substitute yo into the function and solve for x. Since a≠0 we get x= (yo-b)/a. This means xo=(yo-b)/a is a pre-image of yo. This proves that the function y=ax+b where a≠0 is a surjection. (Since there is exactly one pre-image, this function is also an injection.)
Practical example: y= –2x+4. What is the pre-image of y=2? Solution: Here a= –2, i.e. a≠0 and the question is: For what x is y=2? We substitute y=2 into the function. We get x=1, i.e. y(1)=2. So the answer is: x=1 is the pre-image of y=2.
 
Example: The cubic polynomial (of third degree) f(x)=x3-3x is a surjection.
Discussion: The cubic equation x3-3x-yo=0 has real coefficients (a3=1, a2=0, a1=–3, a0=–yo). Every such cubic equation has at least one real root. Since the domain of the polynomial is ℝ, the means that ther is at least one pre-image xo in the domain. That is, (x0)3-3x0-yo=0. So the function is a surjection. (However, this function is not an injection. For example, yo=2 has 2 pre-images: x=–1 and x=2. In fact, every y, –2≤y≤2 has at least 2 pre-images.)
Example: The quadratic function f(x) = x2 is not a surjection. There is no x such that x2 = −1. The range of x² is [0,+∞) , that is, the set of non-negative numbers. (Also, this function is not an injection.)

Note: One can make a non-surjective function into a surjection by restricting its codomain to elements of its range. For example, the  new function, fN(x):ℝ → [0,+∞) where fN(x) = x2 is a surjective function. (This is not the same as the restriction of a function which restricts the domain!)

Example: The exponential function f(x) = 10x is not a surjection. The range of 10x is (0,+∞), that is, the set of positive numbers. (This function is an injection.)

Other examples with real-valued functions

Example: The logarithmic function base 10  f(x):(0,+∞)→ℝ defined by f(x)=log(x) or y=log10(x) is a surjection (and an injection). (This is the inverse function of 10x.)

The projection of a Cartesian product  onto one of its factors is a surjection.