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π Williams syndrome
Williams syndrome (WS) is a genetic disorder that affects many parts of the body. Facial features frequently include a broad forehead, short nose and full cheeks, an appearance that has been described as "elfin". While mild to moderate intellectual disability with particular problems with visual spatial tasks such as drawing is typical, verbal skills are generally relatively unaffected. Those affected often have an outgoing personality, interact readily with strangers, and appear happy. Problems with teeth, heart problems, especially supravalvular aortic stenosis, and periods of high blood calcium are common.
Williams syndrome is caused by a genetic abnormality, specifically a deletion of about 27 genes from the long arm of one of the two chromosome 7s. Typically this occurs as a random event during the formation of the egg or sperm from which a person develops. In a small number of cases, it is inherited from an affected parent in an autosomal dominant manner. The different characteristic features have been linked to the loss of specific genes. The diagnosis is typically suspected based on symptoms and confirmed by genetic testing.
Treatment includes special education programs and various types of therapy. Surgery may be done to correct heart problems. Dietary changes or medications may be required for high blood calcium. The syndrome was first described in 1961 by New Zealander John C. P. Williams. Williams syndrome affects between 1 in 7,500 to 1 in 20,000 people at birth. Life expectancy is less than that of the general population, mostly due to the increased rates of heart disease.
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- "Williams syndrome" | 2020-01-18 | 13 Upvotes 7 Comments
π Verlan: French slang that inverses words
Verlan (French pronunciation:Β β[vΙΚlΙΜ]), (verlan is the reverse of the expression "l'envers") is a type of argot in the French language, featuring inversion of syllables in a word, and is common in slang and youth language. It rests on a long French tradition of transposing syllables of individual words to create slang words. The name verlan itself is an example: it is derived from inverting the sounds of the syllables in l'envers ([lΙΜvΙΚ], "the inverse", frequently used in the sense of "back-to-front").
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- "Verlan: French slang that inverses words" | 2020-02-02 | 178 Upvotes 240 Comments
π Cupellation
Cupellation is a refining process in metallurgy where ores or alloyed metals are treated under very high temperatures and have controlled operations to separate noble metals, like gold and silver, from base metals, like lead, copper, zinc, arsenic, antimony, or bismuth, present in the ore. The process is based on the principle that precious metals do not oxidise or react chemically, unlike the base metals, so when they are heated at high temperatures, the precious metals remain apart, and the others react, forming slags or other compounds.
Since the Early Bronze Age, the process was used to obtain silver from smelted lead ores. By the Middle Ages and the Renaissance, cupellation was one of the most common processes for refining precious metals. By then, fire assays were used for assaying minerals, that is, testing fresh metals such as lead and recycled metals to know their purity for jewellery and coin making. Cupellation is still in use today.
Discussed on
- "Cupellation" | 2021-11-25 | 24 Upvotes 2 Comments
π Facebook unceremoniously kills off Meta brand
Meta is a company performing big data analysis of scientific literature. Company is headquartered in Redwood City, California (formerly Toronto, Ontario, Canada) and operates Meta Science, a literature discovery platform. The company was acquired by the Chan Zuckerberg Initiative in 2017.
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- "Facebook unceremoniously kills off Meta brand" | 2021-10-29 | 37 Upvotes 7 Comments
π List of Assassination Attempts on Adolf Hitler
This is an incomplete list of documented attempts to assassinate Adolf Hitler.
All attempts occurred in the German Reich, except where noted. All attempts involved citizens of the German Reich, except where noted. No fewer than 42 plots have been uncovered by historians. However, the true numbers cannot be accurately determined due to an unknown number of undocumented cases.
Discussed on
- "List of Assassination Attempts on Adolf Hitler" | 2019-11-06 | 55 Upvotes 30 Comments
π Tupolev Tu-144
The Tupolev Tu-144 (Russian: TyΠΏΠΎΠ»Π΅Π² Π’Ρ-144; NATO reporting name: Charger) is a retired jet airliner and commercial supersonic transport aircraft (SST). It was the world's first commercial SST (maiden flight β 31 December 1968), the second being the Anglo-French Concorde (maiden flight β 2 March 1969). The design was a product of the Tupolev design bureau, headed by Alexei Tupolev, of the Soviet Union and manufactured by the Voronezh Aircraft Production Association in Voronezh, Russia. It conducted 102 commercial flights, of which only 55 carried passengers, at an average service altitude of 16,000 metres (52,000Β ft) and cruised at a speed of around 2,000 kilometres per hour (1,200Β mph) (Mach 1.6).
The prototype's first flight was made on 31 December 1968, near Moscow from Zhukovsky Airport, two months before the first flight of Concorde. The Tu-144 first went supersonic on 5 June 1969 (Concorde first went supersonic on 1 October 1969), and on 26 May 1970 became the world's first commercial transport to exceed Mach 2. The aircraft used a new construction technique which resulted in large unexpected cracks, which resulted in several crashes. A Tu-144 crashed in 1973 at the Paris Air Show, delaying its further development. The aircraft was introduced into commercial service on 26 December 1975. In May 1978, another Tu-144 (an improved version, the Tu-144D) crashed on a test flight while being delivered. The aircraft remained in use as a cargo aircraft until 1983, when the Tu-144 commercial fleet was grounded. The Tu-144 was later used by the Soviet space program to train pilots of the Buran spacecraft, and by NASA for supersonic research until 1999, when the Tu-144 made its last flight (26 June 1999).
Discussed on
- "Tupolev Tu-144" | 2013-10-20 | 39 Upvotes 18 Comments
π Paige Compositor
The Paige Compositor was an invention developed by James W. Paige (1842β1917) between 1872 and 1888. It was designed to replace the human typesetter of a lead type-composed printing form with a mechanical arm. In the early 1890s, a group of inventors signed a contract with Towner K. Webster in Chicago to produce 3000 compositors. However, the machine was not nearly as precise as it should have been and never turned a profit because of its complexity and continual need for adjustment based upon trial and error. As a result, it was the Linotype typesetting machine, which composed in a hot metal typesetting process, that became the new popular typesetting machine.
The Paige typesetting machine is notable for substantial investment that the prominent writer Mark Twain made into the failed endeavor: $300,000 ($6,000,000 today). Twain, a former printer, invested not only the bulk of his book profits but also a large portion of the inheritance of Olivia Clemens, his wife. Many point to his over-investment in the Paige typesetting machine and other inventions as the cause of not only his family's financial decline but also the decline of his wit and humor.
Webster Manufacturing made fewer than six machines costing $15,000 apiece, over three times as much as the initial production estimates. One was donated by Cornell University for a scrap metal drive during World War II. The only surviving machine is displayed at the Mark Twain House in Hartford, Connecticut.
Discussed on
- "Paige Compositor" | 2021-07-29 | 12 Upvotes 1 Comments
π Gibbs Phenomenon
In mathematics, the Gibbs phenomenon, discovered by Henry WilbrahamΒ (1848) and rediscovered by J. Willard GibbsΒ (1899), is the peculiar manner in which the Fourier series of a piecewise continuously differentiable periodic function behaves at a jump discontinuity. The nth partial sum of the Fourier series has large oscillations near the jump, which might increase the maximum of the partial sum above that of the function itself. The overshoot does not die out as n increases, but approaches a finite limit. This sort of behavior was also observed by experimental physicists, but was believed to be due to imperfections in the measuring apparatus.
This is one cause of ringing artifacts in signal processing.
Discussed on
- "Gibbs Phenomenon" | 2021-06-01 | 40 Upvotes 27 Comments
π Satellite Babies
Satellite babies (also called Satellite Children) refer to immigrantsβ children who are temporarily sent back to their home country by their parents to be reared by extended family. Typically, the satellite babies are born in the host country and sent back as infants, returning to their parents in time to start schooling or when their parents have established financial stability. Research and media articles on satellite babies have predominantly focused on the topic from a Chinese-American context. Satellite babies have become more prevalent in recent decades due to globalisation, prompting researchers and social workers to raise concerns about the psychological impacts of repeated attachment disruptions and acculturation associated with satellite babies.
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- "Satellite Babies" | 2020-05-11 | 33 Upvotes 20 Comments
π Pareto Front
In multi-objective optimization, the Pareto front (also called Pareto frontier or Pareto curve) is the set of all Pareto efficient solutions. The concept is widely used in engineering.:β111β148β It allows the designer to restrict attention to the set of efficient choices, and to make tradeoffs within this set, rather than considering the full range of every parameter.:β63β65β:β399β412β