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🔗 Computer science

In computer architecture, Amdahl's law (or Amdahl's argument) is a formula which gives the theoretical speedup in latency of the execution of a task at fixed workload that can be expected of a system whose resources are improved. It is named after computer scientist Gene Amdahl, and was presented at the AFIPS Spring Joint Computer Conference in 1967.

Amdahl's law is often used in parallel computing to predict the theoretical speedup when using multiple processors. For example, if a program needs 20 hours to complete using a single thread, but a one-hour portion of the program cannot be parallelized, therefore only the remaining 19 hours (p = 0.95) of execution time can be parallelized, then regardless of how many threads are devoted to a parallelized execution of this program, the minimum execution time cannot be less than one hour. Hence, the theoretical speedup is limited to at most 20 times the single thread performance, ${\displaystyle \left({\dfrac {1}{1-p}}=20\right)}$.

🔗 Biography 🔗 Mathematics 🔗 Environment 🔗 Iran 🔗 Biography/science and academia 🔗 Astronomy 🔗 Geography 🔗 History of Science 🔗 Astrology 🔗 Middle Ages 🔗 Islam 🔗 Middle Ages/History 🔗 Central Asia 🔗 Maps 🔗 Iraq 🔗 Biography/Core biographies 🔗 Islam/Muslim scholars

Muḥammad ibn Mūsā al-Khwārizmī (Persian: Muḥammad Khwārizmī محمد بن موسی خوارزمی‎; c. 780 – c. 850), Arabized as al-Khwarizmi with al- and formerly Latinized as Algorithmi, was a Persian polymath who produced works in mathematics, astronomy, and geography. Around 820 CE he was appointed as the astronomer and head of the library of the House of Wisdom in Baghdad.

Al-Khwarizmi's popularizing treatise on algebra (The Compendious Book on Calculation by Completion and Balancing, c. 813–833 CE) presented the first systematic solution of linear and quadratic equations. One of his principal achievements in algebra was his demonstration of how to solve quadratic equations by completing the square, for which he provided geometric justifications. Because he was the first to treat algebra as an independent discipline and introduced the methods of "reduction" and "balancing" (the transposition of subtracted terms to the other side of an equation, that is, the cancellation of like terms on opposite sides of the equation), he has been described as the father or founder of algebra. The term algebra itself comes from the title of his book (specifically the word al-jabr meaning "completion" or "rejoining"). His name gave rise to the terms algorism and algorithm. His name is also the origin of (Spanish) guarismo and of (Portuguese) algarismo, both meaning digit.

In the 12th century, Latin translations of his textbook on arithmetic (Algorithmo de Numero Indorum) which codified the various Indian numerals, introduced the decimal positional number system to the Western world. The Compendious Book on Calculation by Completion and Balancing, translated into Latin by Robert of Chester in 1145, was used until the sixteenth century as the principal mathematical text-book of European universities.

In addition to his best-known works, he revised Ptolemy's Geography, listing the longitudes and latitudes of various cities and localities. He further produced a set of astronomical tables and wrote about calendaric works, as well as the astrolabe and the sundial. He also made important contributions to trigonometry, producing accurate sine and cosine tables, and the first table of tangents.

🔗 Lists 🔗 Brands

The following three lists of generic and genericized trademarks are:

• marks which were originally legally protected trademarks, but have been genericized and have lost their legal status due to becoming generic terms,
• marks which have been abandoned and are now generic terms
• marks which are still legally protected as trademarks, at least in some jurisdictions

🔗 Biography 🔗 Medicine 🔗 Biography/science and academia 🔗 History of Science 🔗 Hungary 🔗 Medicine/Society and Medicine 🔗 Project-independent assessment

Ignaz Philipp Semmelweis (German: [ˈɪɡnaːts ˈzɛml̩vaɪs]; Hungarian: Semmelweis Ignác Fülöp [ˈsɛmmɛlvɛjs ˈiɡnaːts ˈfyløp]; 1 July 1818 – 13 August 1865) was a Hungarian physician and scientist of German descent who was an early pioneer of antiseptic procedures and was described as the "saviour of mothers". Postpartum infection, also known as puerperal fever or childbed fever, consists of any bacterial infection of the reproductive tract following birth and in the 19th century was common and often fatal. Semmelweis discovered that the incidence of infection could be drastically reduced by requiring healthcare workers in obstetrical clinics to disinfect their hands. In 1847, he proposed hand washing with chlorinated lime solutions at Vienna General Hospital's First Obstetrical Clinic, where doctors' wards had thrice the mortality of midwives' wards. The maternal mortality rate dropped from 18% to less than 2%, and he published a book of his findings, Etiology, Concept and Prophylaxis of Childbed Fever, in 1861.

Despite his research, Semmelweis's observations conflicted with the established scientific and medical opinions of the time and his ideas were rejected by the medical community. He could offer no theoretical explanation for his findings of reduced mortality due to hand-washing, and some doctors were offended at the suggestion that they should wash their hands and mocked him for it. In 1865, the increasingly outspoken Semmelweis allegedly suffered a nervous breakdown and was committed to an asylum by his colleagues. In the asylum, he was beaten by the guards. He died 14 days later from a gangrenous wound on his right hand that may have been caused by the beating.

His findings earned widespread acceptance only years after his death, when Louis Pasteur confirmed the germ theory, giving Semmelweis' observations a theoretical explanation, and Joseph Lister, acting on Pasteur's research, practised and operated using hygienic methods with great success.

🔗 Biography 🔗 Mathematics 🔗 Australia 🔗 Biography/science and academia

Terence Chi-Shen Tao (born 17 July 1975) is an Australian-American mathematician who has worked in various areas of mathematics. He currently focuses on harmonic analysis, partial differential equations, algebraic combinatorics, arithmetic combinatorics, geometric combinatorics, probability theory, compressed sensing and analytic number theory. As of 2015, he holds the James and Carol Collins chair in mathematics at the University of California, Los Angeles.

Tao was a recipient of the 2006 Fields Medal and the 2014 Breakthrough Prize in Mathematics. He is also a 2006 MacArthur Fellow. Tao has been the author or co-author of 275 research papers.

Tao is the second mathematician of Han Chinese descent to win the Fields medal after Shing-Tung Yau, and the first Australian citizen to win the medal.

🔗 History 🔗 Lists 🔗 Philosophy 🔗 Philosophy/Philosophical literature 🔗 Bibliographies

This is a list of important publications in philosophy, organized by field. The publications on this list are regarded as important because they have served or are serving as one or more of the following roles:

• Foundation – A publication whose ideas would go on to be the foundation of a topic or field within philosophy.
• Breakthrough – A publication that changed or added to philosophical knowledge significantly.
• Influence – A publication that has had a significant impact on the academic study of philosophy or the world.

🔗 Philosophy 🔗 Skepticism 🔗 Psychology

Brandolini's law, also known as the bullshit asymmetry principle, is an internet adage which emphasizes the difficulty of debunking bullshit: "The amount of energy needed to refute bullshit is an order of magnitude bigger than to produce it."

🔗 Human rights 🔗 History 🔗 Military history 🔗 Crime 🔗 Death 🔗 China 🔗 Politics 🔗 Socialism 🔗 Law Enforcement 🔗 Sociology 🔗 Guild of Copy Editors 🔗 Military history/Cold War 🔗 Military history/Asian military history 🔗 Military history/Chinese military history 🔗 Crime and Criminal Biography

The Tiananmen Square protests, also known as the June Fourth Incident (Chinese: 六四事件; pinyin: liùsì shìjiàn) in China, were student-led demonstrations held in Tiananmen Square, Beijing during 1989. In what is known as the Tiananmen Square Massacre (Chinese: 天安门大屠杀; pinyin: Tiān'ānmén dà túshā), troops armed with assault rifles and accompanied by tanks fired at the demonstrators and those trying to block the military's advance into Tiananmen Square. The protests started on 15 April and were forcibly suppressed on 4 June when the government declared martial law and sent the People's Liberation Army to occupy parts of central Beijing. Estimates of the death toll vary from several hundred to several thousand, with thousands more wounded. The popular national movement inspired by the Beijing protests is sometimes called the '89 Democracy Movement (Chinese: 八九民运; pinyin: Bājiǔ mínyùn) or the Tiananmen Square Incident (Chinese: 天安门事件; pinyin: Tiān'ānmén shìjiàn).

The protests were precipitated by the death of pro-reform Chinese Communist Party (CCP) general secretary Hu Yaobang in April 1989 amid the backdrop of rapid economic development and social change in post-Mao China, reflecting anxieties among the people and political elite about the country's future. The reforms of the 1980s had led to a nascent market economy that benefited some people but seriously disadvantaged others, and the one-party political system also faced a challenge to its legitimacy. Common grievances at the time included inflation, corruption, limited preparedness of graduates for the new economy, and restrictions on political participation. Although they were highly disorganized and their goals varied, the students called for greater accountability, constitutional due process, democracy, freedom of the press, and freedom of speech. At the height of the protests, about one million people assembled in the Square.

As the protests developed, the authorities responded with both conciliatory and hardline tactics, exposing deep divisions within the party leadership. By May, a student-led hunger strike galvanized support around the country for the demonstrators, and the protests spread to some 400 cities. Among the CCP's top leadership, Premier Li Peng and Party Elders Li Xiannian and Wang Zhen called for decisive action through violent suppression of the protesters, and ultimately managed to win over Paramount Leader Deng Xiaoping and President Yang Shangkun to their side. On 20 May, the State Council declared martial law. They mobilized as many as ~300,000 troops to Beijing. The troops advanced into central parts of Beijing on the city's major thoroughfares in the early morning hours of 4 June, killing both demonstrators and bystanders in the process. The military operations were under the overall command of General Yang Baibing, half-brother of President Yang Shangkun.

The international community, human rights organizations, and political analysts condemned the Chinese government for the massacre. Western countries imposed arms embargoes on China. The Chinese government made widespread arrests of protesters and their supporters, suppressed other protests around China, expelled foreign journalists, strictly controlled coverage of the events in the domestic press, strengthened the police and internal security forces, and demoted or purged officials it deemed sympathetic to the protests. More broadly, the suppression ended the political reforms begun in 1986 and halted the policies of liberalization of the 1980s, which were only partly resumed after Deng Xiaoping's Southern Tour in 1992. Considered a watershed event, reaction to the protests set limits on political expression in China that have lasted up to the present day. Remembering the protests is widely associated with questioning the legitimacy of CCP rule and remains one of the most sensitive and most widely censored topics in China.

🔗 Chemicals

Fluoroantimonic acid is a mixture of hydrogen fluoride and antimony pentafluoride, containing various cations and anions (the simplest being H
₂F⁺
and SbF⁻
₆). This substance is a superacid that can be excess of a quadrillion times stronger than 100% pure sulfuric acid, depending on proportion of its ingredients. It has been shown to protonate even hydrocarbons to afford pentacoordinate carbocations (carbonium ions). Extreme caution needs to be in place when handling fluoroantimonic acid. It is exceptionally corrosive, but can be stored in containers lined with PTFE (Teflon).

🔗 Economics

The Sam Vimes "Boots" theory of socioeconomic unfairness, often called simply the boots theory, is an economic theory first popularised by English fantasy writer Terry Pratchett in his 1993 Discworld novel Men at Arms. In the novel, Sam Vimes, the captain of the Ankh-Morpork City Watch, reasons that poverty causes greater expenses to the poor than to those who are richer. Since its publication, the theory has received wider attention, especially in regard to the effect of increasing prices of daily necessities.