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🔗 Biography 🔗 Mathematics 🔗 Biography/science and academia 🔗 History of Science 🔗 Switzerland 🔗 Genealogy

The Bernoulli family (German pronunciation: [bɛʁˈnʊli]) of Basel was a patrician family, notable for having produced eight mathematically gifted academics who, among them, contributed substantially to the development of mathematics and physics during the early modern period.

🔗 Aviation 🔗 Military history 🔗 Military history/Military aviation 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Aviation/aircraft

The North American F-82 Twin Mustang is the last American piston-engine fighter ordered into production by the United States Air Force. Based on the P-51 Mustang, the F-82 was originally designed as a long-range escort fighter in World War II. The war ended well before the first production units were operational.

In the postwar era, Strategic Air Command used the planes as a long-range escort fighter. Radar-equipped F-82s were used extensively by the Air Defense Command as replacements for the Northrop P-61 Black Widow as all-weather day/night interceptors. During the Korean War, Japan-based F-82s were among the first USAF aircraft to operate over Korea. The first three North Korean aircraft destroyed by U.S. forces were shot down by F-82s, the first being a North-Korean Yak-11 downed over Gimpo Airfield by the USAF 68th Fighter Squadron.

🔗 Chess

Kasparov versus the World was a game of chess played in 1999 over the Internet. Conducting the white pieces, Garry Kasparov faced the rest of the world in consultation, with the World Team moves to be decided by plurality vote. Over 50,000 people from more than 75 countries participated in the game.

The host and promoter of the match was the MSN Gaming Zone, with sponsorship from First USA bank. After 62 moves played over four months, Kasparov won the game. Contrary to expectations, the game produced a mixture of deep tactical and strategic ideas, and although Kasparov won, he admitted that he had never expended as much effort on any other game in his life. He later said, "It is the greatest game in the history of chess. The sheer number of ideas, the complexity, and the contribution it has made to chess make it the most important game ever played."

🔗 Physics

In materials science, disappearing polymorphs (or perverse polymorphism) describes a phenomenon in which a seemingly stable crystal structure is suddenly unable to be produced, instead transforming into a polymorph, or differing crystal structure with the same chemical composition, during nucleation. Sometimes the resulting transformation is extremely hard or impractical to reverse, because the new polymorph may be more stable. It is hypothesized that contact with a single microscopic seed crystal of the new polymorph can be enough to start a chain reaction causing the transformation of a much larger mass of material. Widespread contamination with such microscopic seed crystals may lead to the impression that the original polymorph has "disappeared."

This is of concern to both the pharmaceutical and computer hardware industry, where disappearing polymorphs can ruin the effectiveness of their products, and make it impossible to manufacture the original product if there is any contamination. There have been cases of laboratories growing crystals of a particular structure and when they try to recreate this, the original crystal structure isn't created but a new crystal structure is. The drug paroxetine was subject to a lawsuit that hinged on such a pair of polymorphs, and multiple life-saving drugs, such as ritonavir, have been recalled due to unexpected polymorphism. Although it may seem like a so-called disappearing polymorph has disappeared for good, it is believed that it is always possible in principle to reconstruct the original polymorph, though doing so may be impractically difficult. Disappearing polymorphs are generally metastable forms, that are replaced by a more stable form.

It is hypothesized that "unintentional seeding" may also be responsible for the phenomenon in which it often becomes easier to crystallize synthetic compounds over time.

🔗 Canada 🔗 Geology 🔗 Canada/Ontario 🔗 Canada/Manitoba 🔗 Canada/Geography of Canada 🔗 Lakes 🔗 Canada/Saskatchewan

Lake Agassiz was a very large glacial lake in central North America. Fed by glacial meltwater at the end of the last glacial period, its area was larger than all of the modern Great Lakes combined though its mean depth was not as great as that of many major lakes today.

First postulated in 1823 by William H. Keating, it was named by Warren Upham in 1879 after Louis Agassiz, when Upham recognized that the lake was formed by glacial action.

🔗 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.

Below is a mostly comprehensive gallery of all images — illustrations, diagrams and animations — that I have created for Wikipedia over the years, some of which have been selected as featured pictures, or even picture of the day. As you'll probably notice, they're mostly related to physics and mathematics, which are my main areas of interest.

If you have any comments, requests, suggestions or corrections, feel free to drop me a message on my talk page. But please, before making a suggestion, first take a look and see what sort of stuff I can do. Due to time, knowledge and complexity constraints, I cannot guarantee I'll be able to make a good illustration of any topic.

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🔗 Business 🔗 Parliamentary Procedure

Robert's Rules of Order, often simply referred to as Robert's Rules, is a manual of parliamentary procedure by U.S. Army officer Henry Martyn Robert. "The object of Rules of Order is to assist an assembly to accomplish the work for which it was designed [...] Where there is no law [...] there is the least of real liberty". The term "Robert's Rules of Order" is also used more generically to refer to any of the more recent editions, by various editors and authors, based on any of Robert's original editions, and the term is used more generically in the United States to refer to parliamentary procedure.

Robert's manual was first published in 1876 as an adaptation of the rules and practice of the United States Congress to the needs of non-legislative societies. Robert's Rules is the most widely used manual of parliamentary procedure in the United States. It governs the meetings of a diverse range of organizations—including church groups, county commissions, homeowners associations, nonprofit associations, professional societies, school boards, and trade unions—that have adopted it as their parliamentary authority. Robert published four editions of the manual before his death in 1923, the last being the thoroughly revised and expanded Fourth Edition published as Robert's Rules of Order Revised in May 1915.

🔗 Iran 🔗 Alternative Views 🔗 Iraq

The Baghdad Battery or Parthian Battery is a set of three artifacts which were found together: a ceramic pot, a tube of copper, and a rod of iron. It was discovered in modern Khujut Rabu, Iraq, close to the metropolis of Ctesiphon, the capital of the Parthian (150 BC – 223 AD) and Sasanian (224–650 AD) empires of Persia, and it is considered to date from either of these periods.

Its origin and purpose remain unclear. It was hypothesized by some researchers that the object functioned as a galvanic cell, possibly used for electroplating, or some kind of electrotherapy, but there is no electroplated object known from this period. An alternative explanation is that it functioned as a storage vessel for sacred scrolls.

🔗 Technology 🔗 Physics 🔗 Telecommunications 🔗 Radio 🔗 Electronics 🔗 Engineering

In antenna theory, a phased array usually means an electronically scanned array, a computer-controlled array of antennas which creates a beam of radio waves that can be electronically steered to point in different directions without moving the antennas. The general theory of an electromagnetic phased array also finds applications in ultrasonic and medical imaging application (phased array ultrasonics) and in optics optical phased array.

In a simple array antenna, the radio frequency current from the transmitter is fed to multiple individual antenna elements with the proper phase relationship so that the radio waves from the separate elements combine (superpose) to form beams, to increase power radiated in desired directions and suppress radiation in undesired directions. In a phased array, the power from the transmitter is fed to the radiating elements through devices called phase shifters, controlled by a computer system, which can alter the phase or signal delay electronically, thus steering the beam of radio waves to a different direction. Since the size of an antenna array must extend many wavelengths to achieve the high gain needed for narrow beamwidth, phased arrays are mainly practical at the high frequency end of the radio spectrum, in the UHF and microwave bands, in which the operating wavelengths are conveniently small.

Phased arrays were originally conceived for use in military radar systems, to steer a beam of radio waves quickly across the sky to detect planes and missiles. These systems are now widely used and have spread to civilian applications such as 5G MIMO for cell phones. The phased array principle is also used in acoustics, and phased arrays of acoustic transducers are used in medical ultrasound imaging scanners (phased array ultrasonics), oil and gas prospecting (reflection seismology), and military sonar systems.

The term "phased array" is also used to a lesser extent for unsteered array antennas in which the phase of the feed power and thus the radiation pattern of the antenna array is fixed. For example, AM broadcast radio antennas consisting of multiple mast radiators fed so as to create a specific radiation pattern are also called "phased arrays".