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🔗 Mathematics

Gabriel's horn (also called Torricelli's trumpet) is a geometric figure which has infinite surface area but finite volume. The name refers to the Abrahamic tradition identifying the archangel Gabriel as the angel who blows the horn to announce Judgment Day, associating the divine, or infinite, with the finite. The properties of this figure were first studied by Italian physicist and mathematician Evangelista Torricelli in the 17th century.

🔗 History 🔗 Military history 🔗 Military history/Early Modern warfare 🔗 European history

The "General Crisis" is the term used by some historians to describe the period of widespread conflict and instability that occurred from the early 17th century to the early 18th century in Europe and in more recent historiography in the world at large. The concept is much debated by historians; there is no consensus.

The term was coined by Eric Hobsbawm in his pair of 1954 articles entitled "The Crisis of the Seventeenth Century" published in Past and Present.

🔗 Brands 🔗 Time

Atmos is the brand name of a mechanical torsion pendulum clock manufactured by Jaeger-LeCoultre in Switzerland which does not need to be wound manually. It gets the energy it needs to run from temperature and atmospheric pressure changes in the environment, and can run for years without human intervention.

The clock is driven by a mainspring, which is wound by the expansion and contraction of liquid and gaseous ethyl chloride in an internal hermetically sealed bellows. The ethyl chloride vaporises into an expansion chamber as the temperature rises, compressing a spiral spring; with a fall in temperature the gas condenses and the spring slackens. This motion constantly winds the mainspring. A temperature variation of only one degree in the range between 15 °C (59 °F) and 30 °C (86 °F), or a pressure variation of 3 mmHg, is sufficient for two days' operation.

In order to run the clock on this small amount of energy, everything inside the Atmos has to work in as friction-free a manner as possible. For timekeeping it uses a torsion pendulum, which consumes less energy than an ordinary pendulum. The torsion pendulum has a period of precisely one minute; thirty seconds to rotate in one direction and thirty seconds to return to the starting position. This is thirty times slower than the 0.994 m (39.1 in) seconds pendulum typically found in a longcase clock, where each swing (or half-period) takes one second.

🔗 Iran

Taarof or Tarof (also transliterated as Taʿârof; Persian: تعارف‎) is a Persian word which refers to an Iranian form of civility or art of etiquette that emphasizes both deference and social rank.

Etymologically the origins of the word trace back to an Arabic word meaning "acquaintance" or "knowledge", but Iranians have transformed taarof into something "uniquely Iranian" and tend to understand it as a ritual politeness that levels the playing field and promotes equality in a hierarchical culture. Taarof between friends, or a host and guest, emphasizes the value of friendship as a priority to everything else in the world. Another understanding is that taarof is a way of managing social relations with decorous manners. It could be used as a basis for mutual goodwill (positively) or as "a social or political weapon that confuses the recipient and puts him at a disadvantage" (negatively). Those who are intimately familiar with Iranian culture seem to agree that taarof is one of the most fundamental things to understand about Iranian culture.

According to Middle East scholar William O. Beeman, "Taarof is an extraordinarily difficult concept encompassing a broad complex of behaviors which mark and underscore differences in social status." For example, in Iranian culture, whoever walks through a doorway first gets a form of status, but the person who makes the other go through the door first also gains status by having made the other person do it through their show of grace and deference. When it comes to matters of rank, "one defers to superiors (tribute), and confers on inferiors (favor), presses honor on equals (neither tribute nor favor) or accepts the honor from a proper source, and thereby "wins". Status is relative for individuals in different interactions, according to Beeman, and rights and obligations shift constantly with changes in social environments.

🔗 United States 🔗 Biography 🔗 California 🔗 Computing 🔗 Computing/Software 🔗 United States/Washington - Seattle 🔗 United States/Washington

Gary Arlen Kildall (; May 19, 1942 – July 11, 1994) was an American computer scientist and microcomputer entrepreneur who created the CP/M operating system and founded Digital Research, Inc. (DRI). Kildall was one of the first people to see microprocessors as fully capable computers, rather than equipment controllers, and to organize a company around this concept. He also co-hosted the PBS TV show The Computer Chronicles. Although his career in computing spanned more than two decades, he is mainly remembered in connection with IBM's unsuccessful attempt in 1980 to license CP/M for the IBM Personal Computer.

🔗 Psychology

Psychohistory is an amalgam of psychology, history, and related social sciences and the humanities. It examines the "why" of history, especially the difference between stated intention and actual behavior. Psychobiography, childhood, group dynamics, mechanisms of psychic defense, dreams, and creativity are primary areas of research. It works to combine the insights of psychology, especially psychoanalysis, with the research methodology of the social sciences and humanities to understand the emotional origin of the behavior of individuals, groups and nations, past and present. Work in the field has been done in the areas of childhood, creativity, dreams, family dynamics, overcoming adversity, personality, political and presidential psychobiography. There are major psychohistorical studies of studies of anthropology, art, ethnology, history, politics and political science, and much else.

🔗 United States 🔗 United States/Arizona 🔗 London Transport

London Bridge is a bridge in Lake Havasu City, Arizona. It was built in the 1830s and formerly spanned the River Thames in London, England. It was dismantled in 1967 and relocated to Arizona. The Arizona bridge is a reinforced concrete structure clad in the original masonry of the 1830s bridge, which was purchased by Robert P. McCulloch from the City of London. McCulloch had exterior granite blocks from the original bridge numbered and transported to America to construct the present bridge in Lake Havasu City, a planned community he established in 1964 on the shore of Lake Havasu. The bridge was completed in 1971 (along with a canal), and links an island in the Colorado River with the main part of Lake Havasu City.

🔗 China

Counting rods (traditional Chinese: 籌; simplified Chinese: 筹; pinyin: chóu; Japanese: 算木; rōmaji: sangi; Korean: sangaji) are small bars, typically 3–14 cm long, that were used by mathematicians for calculation in ancient East Asia. They are placed either horizontally or vertically to represent any integer or rational number.

The written forms based on them are called rod numerals. They are a true positional numeral system with digits for 1–9 and a blank for 0, from the Warring states period (circa 475 BCE) to the 16th century.

🔗 Novels 🔗 Radio 🔗 Novels/Science fiction 🔗 Novels/Short story

"The Machine Stops" is a science fiction short story (12,300 words) by E. M. Forster. After initial publication in The Oxford and Cambridge Review (November 1909), the story was republished in Forster's The Eternal Moment and Other Stories in 1928. After being voted one of the best novellas up to 1965, it was included that same year in the populist anthology Modern Short Stories. In 1973 it was also included in The Science Fiction Hall of Fame, Volume Two.

The story, set in a world where humanity lives underground and relies on a giant machine to provide its needs, predicted technologies similar to instant messaging and the Internet.

🔗 Biography 🔗 Aviation 🔗 France 🔗 Biography/science and academia 🔗 Brazil 🔗 Aviation/aerospace biography 🔗 Brazil/Education and Science in Brazil

Alberto Santos-Dumont (Brazilian Portuguese: [awˈbɛɾtu ˈsɐ̃tus duˈmõ]; 20 July 1873 – 23 July 1932) was a Brazilian inventor and aviation pioneer, one of the very few people to have contributed significantly to the development of both lighter-than-air and heavier-than-air aircraft.

The heir of a wealthy family of coffee producers, Santos-Dumont dedicated himself to aeronautical study and experimentation in Paris, where he spent most of his adult life. In his early career he designed, built, and flew hot air balloons and early dirigibles, culminating in his winning the Deutsch de la Meurthe prize on 19 October 1901 for a flight that rounded the Eiffel Tower. He then turned to heavier-than-air machines, and on 23 October 1906 his 14-bis made the first powered heavier-than-air flight in Europe to be certified by the Aéro-Club de France and the Fédération Aéronautique Internationale. His conviction that aviation would usher in an era of worldwide peace and prosperity led him to freely publish his designs and forego patenting his various innovations.

Santos-Dumont is a national hero in Brazil, where it is popularly held that he preceded the Wright brothers in demonstrating a practical airplane. Countless roads, plazas, schools, monuments, and airports there are dedicated to him, and his name is inscribed on the Tancredo Neves Pantheon of the Fatherland and Freedom. He was a member of the Brazilian Academy of Letters from 1931 until his suicide in 1932.