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🔗 Physics

The Large Electron–Positron Collider (LEP) was one of the largest particle accelerators ever constructed.

It was built at CERN, a multi-national centre for research in nuclear and particle physics near Geneva, Switzerland. LEP collided electrons with positrons at energies that reached 209 GeV. It was a circular collider with a circumference of 27 kilometres built in a tunnel roughly 100 m (300 ft) underground and passing through Switzerland and France. LEP was used from 1989 until 2000. Around 2001 it was dismantled to make way for the Large Hadron Collider, which re-used the LEP tunnel. To date, LEP is the most powerful accelerator of leptons ever built.

🔗 Internet

Demand Progress is an internet activist-related entity encompassing a 501(c)4 arm sponsored by the 1630 Fund and a 501(c)3 arm sponsored by the New Venture Fund. It specializes in online-intensive and other grassroots activism to support Internet freedom, civil liberties, transparency, and human rights, and in opposition to censorship and corporate control of government. The organization was founded through a petition in opposition to the Combating Online Infringement and Counterfeits Act, sparking the movement that eventually defeated COICA's successor bills, the Stop Online Piracy Act and the PROTECT IP Act, two highly controversial pieces of United States legislation.

The organization has continued to fight for such causes in the wake of the successful shelving of these two acts. Demand Progress has also played key roles in forwarding the passage of net neutrality rules, blocking expansion of the Computer Fraud and Abuse Act, under which co-founder Aaron Swartz was indicted, and other key legislative efforts. Estimated membership numbers in early 2015 weigh in at over two million. As of late 2013, the organization encompasses the Demand Progress, Rootstrikers and Watchdog.net wings/brands.

🔗 Technology 🔗 Aviation 🔗 Military history 🔗 Military history/Military aviation 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry 🔗 Aviation/aircraft 🔗 Military history/World War I 🔗 Firearms

A synchronization gear, or a gun synchronizer, sometimes rather less accurately called an interrupter, is attached to the armament of a single-engine tractor-configuration aircraft so it can fire through the arc of its spinning propeller without bullets striking the blades. The idea presupposes a fixed armament directed by aiming the aircraft in which it is fitted at the target, rather than aiming the gun independently.

There are many practical problems, mostly arising from the inherently imprecise nature of an automatic gun's firing, the great (and varying) velocity of the blades of a spinning propeller, and the very high speed at which any gear synchronizing the two has to operate.

Design and experimentation with gun synchronization had been underway in France and Germany in 1913–1914, following the ideas of August Euler, who seems to have been the first to suggest mounting a fixed armament firing in the direction of flight (in 1910). However, the first practical—if far from reliable—gear to enter operational service was that fitted to the Eindecker monoplane fighters, which entered squadron service with the German Air Service in mid-1915. The success of the Eindecker led to numerous gun synchronization devices, culminating in the reasonably reliable hydraulic British Constantinesco gear of 1917. By the end of the war German engineers were well on the way to perfecting a gear using an electrical rather than a mechanical or hydraulic link between the engine and the gun, with the gun being triggered by a solenoid rather than by a mechanical "trigger motor".

From 1918 to the mid-1930s the standard armament for a fighter aircraft remained two synchronized rifle-calibre machine guns, firing forward through the arc of the propeller. During the late 1930s, however, the main role of the fighter was increasingly seen as the destruction of large, all-metal bombers, for which the "traditional" light armament was inadequate.

Since it was impractical to try to fit more than one or two extra guns in the limited space available in the front of a single-engine aircraft's fuselage, this led to an increasing proportion of the armament being mounted in the wings, firing outside the arc of the propeller. There were in fact some advantages in dispensing with centrally mounted guns altogether. Nevertheless, the conclusive redundancy of synchronization gears did not finally come until the introduction of jet propulsion and the absence of a propeller for guns to be synchronized with.

🔗 History 🔗 Mathematics 🔗 Books 🔗 Greece 🔗 History of Science

The Archimedes Palimpsest is a parchment codex palimpsest, originally a Byzantine Greek copy of a compilation of Archimedes and other authors. It contains two works of Archimedes that were thought to have been lost (the Ostomachion and the Method of Mechanical Theorems) and the only surviving original Greek edition of his work On Floating Bodies. The first version of the compilation is believed to have been produced by Isidorus of Miletus, the architect of the geometrically complex Hagia Sophia cathedral in Constantinople, sometime around AD 530. The copy found in the palimpsest was created from this original, also in Constantinople, during the Macedonian Renaissance (c. AD 950), a time when mathematics in the capital was being revived by the former Greek Orthodox bishop of Thessaloniki Leo the Geometer, a cousin of the Patriarch.

Following the sack of Constantinople by Western crusaders in 1204, the manuscript was taken to an isolated Greek monastery in Palestine, possibly to protect it from occupying crusaders, who often equated Greek script with heresy against their Latin church and either burned or looted many such texts (including at least two other copies of Archimedes). The complex manuscript was not appreciated at this remote monastery and was soon overwritten (1229) with a religious text. In 1899, nine hundred years after it was written, the manuscript was still in the possession of the Greek church, and back in Istanbul, where it was catalogued by the Greek scholar Papadopoulos-Kerameus, attracting the attention of Johan Heiberg. Heiberg visited the church library and was allowed to make detailed photographs in 1906. Most of the original text was still visible, and Heiberg published it in 1915. In 1922 the manuscript went missing in the midst of the evacuation of the Greek Orthodox library in Istanbul, during a tumultuous period following the World War I. Concealed for over 70 years by a Western businessman, forged pictures were painted on top of some text to increase resale value. Unable to sell the book privately, in 1998 the businessman's daughter risked a public auction in New York contested by the Greek church; the U.S. court ruled for the auction, and the manuscript was purchased by an anonymous buyer (rumored to be Jeff Bezos). The texts under the forged pictures, and previously unreadable texts, were revealed by analyzing images produced by ultraviolet, infrared, visible and raking light, and X-ray.

All images and transcriptions are now freely available on the web at the Archimedes Digital Palimpsest under the Creative Commons License CC BY.

🔗 Brands 🔗 Electronics

The Capacitance Electronic Disc (CED) is an analog video disc playback system developed by RCA, in which video and audio could be played back on a TV set using a special needle and high-density groove system similar to phonograph records.

First conceived in 1964, the CED system was widely seen as a technological success which was able to increase the density of a long-playing record by two orders of magnitude. Despite this achievement, the CED system fell victim to poor planning, various conflicts with RCA management, and several technical difficulties that slowed development and stalled production of the system for 17 years—until 1981, by which time it had already been made obsolete by laser videodisc (DiscoVision, later called LaserVision and LaserDisc) as well as Betamax and VHS video cassette formats. Sales for the system were nowhere near projected estimates. In the spring of 1984, RCA announced it was discontinuing player production, but continuing the production of videodiscs until 1986, losing an estimated $600 million in the process. RCA had initially intended to release the SKT425 CED player with their high end Dimensia system in late 1984, but cancelled CED player production prior to the Dimensia system's release.

The format was commonly known as "videodisc", leading to much confusion with the contemporaneous LaserDisc format. LaserDiscs are read optically with a laser beam, whereas CED discs are read physically with a stylus (similar to a conventional gramophone record). The two systems are mutually incompatible.

RCA used the brand "SelectaVision" for the CED system, a name also used for some early RCA brand VCRs, and other experimental projects at RCA.

🔗 Typography

A California job case is a kind of type case: a compartmentalized wooden box used to store movable type used in letterpress printing. It was the most popular and accepted of the job case designs in America. The California job case took its name from the Pacific Coast location of the foundries that made the case popular.

The defining characteristic of the California job case is the layout, documented by J. L. Ringwalt in the American Encyclopaedia of Printing in 1871, as used by San Francisco printers. This modification of a previously popular case, the Italic, it was claimed reduced the compositor's hand travel as he set the pieces of type into his composing stick by more than half a mile per day. In the previous convention, upper- and lowercase type were kept in separate cases, or trays. This is why capital letters are called uppercase and the minuscules are lowercase. The combined case became popular during the western expansion of the United States in the 19th century.

🔗 Biography 🔗 Women scientists 🔗 Biography/science and academia 🔗 Women's History 🔗 Astronomy 🔗 Smithsonian Institution Archives

Cecilia Helena Payne-Gaposchkin (née Payne; (1900-05-10)May 10, 1900 – (1979-12-07)December 7, 1979) was a British-born American astronomer and astrophysicist who proposed in her 1925 doctoral thesis that stars were composed primarily of hydrogen and helium. Her groundbreaking conclusion was initially rejected because it contradicted the scientific wisdom of the time, which held that there were no significant elemental differences between the Sun and Earth. Independent observations eventually proved she was actually correct

🔗 Death 🔗 Classical Greece and Rome 🔗 Archaeology

The Hagia Triada Sarcophagus is a late Minoan 137 cm (54 in)-long limestone sarcophagus, dated to about 1400 BC or some decades later, excavated from a chamber tomb at Hagia Triada, Crete in 1903, and now on display in the Heraklion Archaeological Museum ("AMH") in Crete.

Uniquely for such a piece from this date on Crete, it is coated in plaster and painted in fresco on all faces. Otherwise the Minoans (unlike the ancient Egyptians) only used frescoes to decorate palaces and houses for the enjoyment of the living and not in funerary practice. It is the only limestone sarcophagus of its era discovered to date; there are a number of smaller terracotta "ash-chests" (larnax), painted far more crudely, usually in a single colour. It is the only object with a series of narrative scenes of Minoan funerary ritual (later sarcophagi found in the Aegean were decorated with abstract designs and patterns). It was probably originally used for the burial of a prince.

It provides probably the most comprehensive iconography of a pre-Homeric thysiastikis ceremony and one of the best pieces of information on noble burial customs when Crete was under Mycenaean rule, combining features of Minoan and Mycenaean style and subject matter, as well as probable influence from Ancient Egyptian religion.

🔗 Lists 🔗 Martial arts 🔗 Sumo

Kimarite (決まり手, "Deciding technique") are winning techniques in a sumo bout. For each bout in a Grand Sumo tournament (or honbasho), a sumo referee, or gyōji, will decide and announce the type of kimarite used by the winner. It is possible (although rare) for the judges to modify this decision later. Records of the kimarite are kept and statistical information on the preferred techniques of different wrestlers can be deduced easily. For example, a pie chart of the kimarite used by each sekitori in the past year can be found on the Japan Sumo Association webpage.

Since 2001, the Japan Sumo Association recognizes 82 types of kimarite (and 5 winning non-techniques), but only about a dozen are used regularly. For example, yorikiri, oshidashi and hatakikomi are frequent methods used to win bouts. In addition to kimarite, a bout can end in a disqualification if either wrestler makes a foul (禁手, kinjite), such as striking with a closed fist.

The following is a full list of kimarite. Literal translations of the Japanese are also given.

🔗 Computing 🔗 Computing/Software

In computer programming jargon, a heisenbug is a software bug that seems to disappear or alter its behavior when one attempts to study it. The term is a pun on the name of Werner Heisenberg, the physicist who first asserted the observer effect of quantum mechanics, which states that the act of observing a system inevitably alters its state. In electronics the traditional term is probe effect, where attaching a test probe to a device changes its behavior.

Similar terms, such as bohrbug, mandelbug, hindenbug, and schrödinbug (see the section on related terms) have been occasionally proposed for other kinds of unusual software bugs, sometimes in jest; however, unlike the term heisenbug, they are not widely known or used.