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🔗 Technology 🔗 Physics 🔗 Radio 🔗 Astronomy 🔗 Engineering

In engineering, the terahertz gap is a frequency band in the terahertz region of the electromagnetic spectrum between radio waves and infrared light for which practical technologies for generating and detecting the radiation do not exist. It is defined as 0.1 to 10 THz (wavelengths of 3 mm to 30 µm). Currently, at frequencies within this range, useful power generation and receiver technologies are inefficient and unfeasible.

Mass production of devices in this range and operation at room temperature (at which energy k·T is equal to the energy of a photon with a frequency of 6.2 THz) are mostly impractical. This leaves a gap between mature microwave technologies in the highest frequencies of the radio spectrum and the well developed optical engineering of infrared detectors in their lowest frequencies. This radiation is mostly used in small-scale, specialized applications such as submillimetre astronomy. Research that attempts to resolve this issue has been conducted since the late 20th century.

🔗 Mathematics

A self-tiling tile set, or setiset, of order n is a set of n shapes or pieces, usually planar, each of which can be tiled with smaller replicas of the complete set of n shapes. That is, the n shapes can be assembled in n different ways so as to create larger copies of themselves, where the increase in scale is the same in each case. Figure 1 shows an example for n = 4 using distinctly shaped decominoes. The concept can be extended to include pieces of higher dimension. The name setisets was coined by Lee Sallows in 2012, but the problem of finding such sets for n = 4 was asked decades previously by C. Dudley Langford, and examples for polyaboloes (discovered by Martin Gardner, Wade E. Philpott and others) and polyominoes (discovered by Maurice J. Povah) were previously published by Gardner.

🔗 Classical Greece and Rome 🔗 Greece 🔗 Food and drink 🔗 Wine 🔗 Invention

A Pythagorean cup (also known as a Pythagoras cup, Greedy Cup, Tantalus cup or i koupa tis dikaiosynis) is a practical joke device in a form of a drinking cup, credited to Pythagoras of Samos. When it is filled beyond a certain point, a siphoning effect causes the cup to drain its entire contents through the base.

🔗 Media

The Covox Speech Thing is an external audio device attached to the computer to output digital sound. It was composed of a primitive 8-bit DAC using a resistor ladder and an analogue signal output, and plugged into the printer port of the PC.

The Speech Thing was introduced on December 18, 1987 by Covox, Inc of Eugene, Oregon, for about US$70 (US$79.95 as of 1989), but as its parts were much cheaper than the complete plug, and as its design was fairly simple, people soon started to build their own variants. The plug was used long into the 1990s, as sound cards were still very expensive at that time. The plug was also quite popular in the demoscene.

An inherent problem of the design is that it requires very precise resistors. If normal parts are used, the values get shuffled, especially for quiet sounds, resulting in distortion. Nevertheless, the sound quality of the Covox plug is far superior compared to the PC speaker; even today, a self-built Covox plug is still an inexpensive way to give old computers sound capabilities.

🔗 Physics

Flux pinning is the phenomenon where a superconductor is pinned in space above a magnet. The superconductor must be a type-II superconductor because type-I superconductors cannot be penetrated by magnetic fields. The act of magnetic penetration is what makes flux pinning possible. At higher magnetic fields (above Hc1 and below Hc2) the superconductor allows magnetic flux to enter in quantized packets surrounded by a superconducting current vortex (see Quantum vortex). These sites of penetration are known as flux tubes. The number of flux tubes per unit area is proportional to the magnetic field with a constant of proportionality equal to the magnetic flux quantum. On a simple 76 millimeter diameter, 1-micrometer thick disk, next to a magnetic field of 28 kA/m, there are approximately 100 billion flux tubes that hold 70,000 times the superconductor's weight. At lower temperatures the flux tubes are pinned in place and cannot move. This pinning is what holds the superconductor in place thereby allowing it to levitate. This phenomenon is closely related to the Meissner effect, though with one crucial difference — the Meissner effect shields the superconductor from all magnetic fields causing repulsion, unlike the pinned state of the superconductor disk which pins flux, and the superconductor in place.

🔗 Biography 🔗 England 🔗 Disability 🔗 Biography/arts and entertainment

Jeffrey Hudson (1619 – c. 1682) was a court dwarf of the English queen Henrietta Maria of France. He was famous as the "Queen's dwarf" and "Lord Minimus" and was considered one of the "wonders of the age" because of his extreme but well-proportioned smallness. He fought with the Royalists in the English Civil War and fled with the Queen to France but was expelled from her court when he killed a man in a duel. He was captured by Barbary pirates and spent 25 years enslaved in North Africa before being ransomed back to England.

🔗 Psychology 🔗 Sociology

The Ringelmann effect is the tendency for individual members of a group to become increasingly less productive as the size of their group increases. This effect, discovered by French agricultural engineer Maximilien Ringelmann (1861–1931), illustrates the inverse relationship that exists between the size of a group and the magnitude of group members’ individual contribution to the completion of a task. While studying the relationship between process loss (i.e., reductions in performance effectiveness or efficiency) and group productivity, Ringelmann (1913) found that having group members work together on a task (e.g., pulling a rope) actually results in significantly less effort than when individual members are acting alone. Ringelmann discovered that as more and more people are added to a group, the group often becomes increasingly inefficient, ultimately violating the notion that group effort and team participation reliably leads to increased effort on behalf of the members.

🔗 Japan 🔗 Japan/Culture

Cool Japan (クールジャパン, Kūru Japan) refers to the aspects of Japanese culture that non-Japanese people perceive as "cool". The Cool Japan strategy is part of Japan's overall brand strategy, aiming to disseminate Japan's attractiveness and allure to the world. The target of Cool Japan "encompasses everything from games, manga, anime, and other forms of content, fashion, commercial products, Japanese cuisine, and traditional culture to robots, eco-friendly technologies, and other high-tech industrial products".

Cool Japan has been described as a form of soft power, with the ability to "indirectly influence behavior or interests through cultural or ideological means".

🔗 France 🔗 Military history 🔗 Politics 🔗 Military history/Intelligence 🔗 Judaism 🔗 Military history/French military history 🔗 Jewish history 🔗 European history 🔗 Military history/European military history

The Dreyfus Affair (French: l'affaire Dreyfus, pronounced [lafɛːʁ dʁɛfys]) was a political scandal that divided the Third French Republic from 1894 until its resolution in 1906. "The Affair", as it is known in French, has come to symbolise modern injustice in the Francophone world, and it remains one of the most notable examples of a complex miscarriage of justice and antisemitism. The role played by the press and public opinion proved influential in the conflict.

The scandal began in December 1894 when Captain Alfred Dreyfus was convicted of treason. Dreyfus was a 35-year-old Alsatian French artillery officer of Jewish descent. He was sentenced to life imprisonment for allegedly communicating French military secrets to the German Embassy in Paris, and was imprisoned on Devil's Island in French Guiana, where he spent nearly five years.

In 1896, evidence came to light—primarily through an investigation instigated by Georges Picquart, head of counter-espionage—which identified the real culprit as a French Army major named Ferdinand Walsin Esterhazy. When high-ranking military officials suppressed the new evidence, a military court unanimously acquitted Esterhazy after a trial lasting only two days. The Army laid additional charges against Dreyfus, based on forged documents. Subsequently, Émile Zola's open letter J'Accuse…!, stoked a growing movement of support for Dreyfus, putting pressure on the government to reopen the case.

In 1899, Dreyfus was returned to France for another trial. The intense political and judicial scandal that ensued divided French society between those who supported Dreyfus (now called "Dreyfusards"), such as Sarah Bernhardt, Anatole France, Henri Poincaré and Georges Clemenceau, and those who condemned him (the anti-Dreyfusards), such as Édouard Drumont, the director and publisher of the antisemitic newspaper La Libre Parole. The new trial resulted in another conviction and a 10-year sentence, but Dreyfus was pardoned and released. In 1906, Dreyfus was exonerated and reinstated as a major in the French Army. He served during the whole of World War I, ending his service with the rank of lieutenant-colonel. He died in 1935.

The affair from 1894 to 1906 divided France into pro-republican, anticlerical, Dreyfusards and pro-Army, mostly Catholic "anti-Dreyfusards". It embittered French politics and encouraged radicalisation.