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🔗 Computing 🔗 Computing/Software 🔗 Computing/Free and open-source software

xv6 is a modern reimplementation of Sixth Edition Unix in ANSI C for multiprocessor x86 and RISC-V systems. It is used for pedagogical purposes in MIT's Operating Systems Engineering (6.828) course as well as Georgia Tech's (CS 3210) Design of Operating Systems Course, IIIT Hyderabad, IIIT Delhi and as well as many other institutions.

🔗 Computing 🔗 Classical Greece and Rome 🔗 Greece 🔗 Astronomy 🔗 History of Science 🔗 Alternative Views 🔗 Time

The Antikythera mechanism (, ) is an ancient hand powered Greek analogue computer which has also been described as the first example of such device used to predict astronomical positions and eclipses for calendar and astrological purposes decades in advance. It could also be used to track the four-year cycle of athletic games which was similar to an Olympiad, the cycle of the ancient Olympic Games.

This artefact was retrieved from the sea in 1901, and identified on 17 May 1902 as containing a gear by archaeologist Valerios Stais, among wreckage retrieved from a shipwreck off the coast of the Greek island Antikythera. The instrument is believed to have been designed and constructed by Greek scientists and has been variously dated to about 87 BC, or between 150 and 100 BC, or to 205 BC, or to within a generation before the shipwreck, which has been dated to approximately 70–60 BC.

The device, housed in the remains of a 34 cm × 18 cm × 9 cm (13.4 in × 7.1 in × 3.5 in) wooden box, was found as one lump, later separated into three main fragments which are now divided into 82 separate fragments after conservation efforts. Four of these fragments contain gears, while inscriptions are found on many others. The largest gear is approximately 14 centimetres (5.5 in) in diameter and originally had 223 teeth.

It is a complex clockwork mechanism composed of at least 30 meshing bronze gears. A team led by Mike Edmunds and Tony Freeth at Cardiff University used modern computer x-ray tomography and high resolution surface scanning to image inside fragments of the crust-encased mechanism and read the faintest inscriptions that once covered the outer casing of the machine.

Detailed imaging of the mechanism suggests that it had 37 gear wheels enabling it to follow the movements of the Moon and the Sun through the zodiac, to predict eclipses and even to model the irregular orbit of the Moon, where the Moon's velocity is higher in its perigee than in its apogee. This motion was studied in the 2nd century BC by astronomer Hipparchus of Rhodes, and it is speculated that he may have been consulted in the machine's construction.

The knowledge of this technology was lost at some point in antiquity. Similar technological works later appeared in the medieval Byzantine and Islamic worlds, but works with similar complexity did not appear again until the development of mechanical astronomical clocks in Europe in the fourteenth century. All known fragments of the Antikythera mechanism are now kept at the National Archaeological Museum in Athens, along with a number of artistic reconstructions and replicas of the mechanism to demonstrate how it may have looked and worked.

🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry

The demon core was a spherical 6.2-kilogram (14 lb) subcritical mass of plutonium 89 millimetres (3.5 in) in diameter, that was involved in two criticality accidents, on August 21, 1945 and May 21, 1946. The core was intended for use in a third nuclear weapon, but remained in use for testing after Japan's surrender. It was designed with a small safety margin to ensure a successful explosion of the bomb. The device briefly went supercritical when it was accidentally placed in supercritical configurations during two separate experiments intended to guarantee the core was indeed close to the critical point. The incidents happened at the Los Alamos Laboratory in 1945 and 1946, both resulting in the acute radiation poisoning and subsequent deaths of scientists: Harry Daghlian and Louis Slotin. After these incidents the spherical plutonium core was referred to as the "demon core".

🔗 Maps

In cartography, a trap street is a fictitious entry in the form of a misrepresented street on a map, often outside the area the map nominally covers, for the purpose of "trapping" potential copyright violators of the map who, if caught, would be unable to explain the inclusion of the "trap street" on their map as innocent. On maps that are not of streets, other "copyright trap" features (such as nonexistent towns, or mountains with the wrong elevations) may be inserted or altered for the same purpose.

Trap streets are often nonexistent streets; but sometimes, rather than actually depicting a street where none exists, a map will misrepresent the nature of a street in a fashion that can still be used to detect copyright violators but is less likely to interfere with navigation. For instance, a map might add nonexistent bends to a street, or depict a major street as a narrow lane, without changing its location or its connections to other streets.

Trap streets are rarely acknowledged by publishers. One known case is a popular driver's atlas for the city of Athens, Greece, which has a warning inside its front cover that potential copyright violators should beware of trap streets.

🔗 Economics 🔗 Lists

This is a list of some of the major unsolved problems, puzzles, or questions in economics. Some of these are theoretical in origin and some of them concern the inability of orthodox economic theory to explain an empirical observation.

🔗 Technology 🔗 Physics 🔗 Physics/Acoustics

Sonoluminescence is the emission of short bursts of light from imploding bubbles in a liquid when excited by sound.

🔗 Food and drink 🔗 Brands 🔗 Food and drink/Beverages

OK Soda was a soft drink created by The Coca-Cola Company in 1993 that courted the American Generation X demographic with unusual advertising tactics, including neo-noir design, chain letters and deliberately negative publicity. After the soda did not sell well in select test markets, it was officially declared out of production in 1995 before reaching nationwide distribution. The drink's slogan was "Things are going to be OK."

🔗 Internet culture 🔗 Television 🔗 The Simpsons

Flanderization is the process through which a fictional character's essential traits are exaggerated over the course of a serial work. The term flanderization was coined by TV Tropes in reference to Ned Flanders of The Simpsons, who was caricatured over the show's run from a good neighbor who was religious among other characteristics into an evangelical "bible-thumper". Flanderization has been analyzed as an aspect of serial works, especially television comedies, that shows a work's decline.

🔗 Color

Pantone 448 C, also referred to as "the ugliest colour in the world", is a colour in the Pantone colour system. Described as a "drab dark brown", it was selected in 2016 as the colour for plain tobacco and cigarette packaging in Australia, after market researchers determined that it was the least attractive colour. The Australian Department of Health initially referred to the colour as "olive green", but the name was changed after concerns were expressed by the Australian Olive Association.

Since 2016, the same colour has also been used for plain cigarette packaging in France, the United Kingdom, Israel, Norway, New Zealand, Slovenia, Saudi Arabia, and Turkey.

The colour has also been widely but erroneously reported as being known as "opaque couché"; in fact this is simply French for "layered opaque", in reference to being used on coated paper. The confusion appears to have arisen because "PANTONE opaque couché" is the French name of a swatch library (palette) used in Adobe Illustrator containing this colour and intended for printing in solid ink colours on coated paper; in English this library is known as "PANTONE solid coated".