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๐Ÿ”— Aosta Valley Autonomus Region

๐Ÿ”— Italy ๐Ÿ”— Geography

The Aosta Valley (Italian: Valle d'Aosta [หˆvalle daหˆษ”sta] (official) or Val d'Aosta (usual); French: Vallรฉe d'Aoste; Arpitan: Val d'Outa; Walser: Augschtalann or Ougstalland; Piedmontese: Val d'Osta) is a mountainous autonomous region in northwestern Italy. It is bordered by Auvergne-Rhรดne-Alpes, France, to the west, Valais, Switzerland, to the north, and by Piedmont, Italy, to the south and east. The regional capital is Aosta.

Covering an area of 3,263ย km2 (1,260ย sqย mi) and with a population of about 128,000 it is the smallest, least populous, and least densely populated region of Italy. The province of Aosta having been dissolved in 1945, the Aosta Valley region was the first region of Italy to abolish provincial subdivisions. Provincial administrative functions are provided by the regional government. The region is divided into 74 comuni (French: communes).

Italian and French are the official languages, though the native population also speak Valdรดtain, a dialect of Franco-Provenรงal. Italian is spoken as a mother tongue by 77.29% of population, Valdรดtain by 17.91%, and French by 1.25%. In 2009, reportedly 50.53% of the population could speak all three languages.

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๐Ÿ”— Ask HN: using only static magnetism - impossible to stably levitate against gravity?

๐Ÿ”— Mathematics ๐Ÿ”— Physics

Earnshaw's theorem states that a collection of point charges cannot be maintained in a stable stationary equilibrium configuration solely by the electrostatic interaction of the charges. This was first proven by British mathematician Samuel Earnshaw in 1842. It is usually referenced to magnetic fields, but was first applied to electrostatic fields.

Earnshaw's theorem applies to classical inverse-square law forces (electric and gravitational) and also to the magnetic forces of permanent magnets, if the magnets are hard (the magnets do not vary in strength with external fields). Earnshaw's theorem forbids magnetic levitation in many common situations.

If the materials are not hard, Braunbeck's extension shows that materials with relative magnetic permeability greater than one (paramagnetism) are further destabilising, but materials with a permeability less than one (diamagnetic materials) permit stable configurations.

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๐Ÿ”— Janet Airlines

๐Ÿ”— Aviation ๐Ÿ”— Aviation/airline

Janet, sometimes called Janet Airlines, is the unofficial name given to a highly classified fleet of passenger aircraft operated for the United States Department of the Air Force as an employee shuttle to transport military and contractor employees. The purpose is to pick up the employees at their home airport, and take them to their place of work. Then, in the afternoon, they take the employees back to their home airports. The airline mainly serves the Nevada National Security Site (most notably Area 51 and the Tonopah Test Range), from a private terminal at Las Vegas's McCarran International Airport.

The airline's aircraft are generally unmarked, but do have a red paint strip along the windows of the aircraft, which gives some sort of hint at Janet being the operator.

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๐Ÿ”— High Efficiency Image File Format (HEIF/.heic)

๐Ÿ”— Technology ๐Ÿ”— Computing ๐Ÿ”— Computing/Software ๐Ÿ”— Computing/Free and open-source software

High Efficiency Image File Format (HEIF) is a container format for storing individual digital images and image sequences. The standard covers multimedia files that can also include other media streams, such as timed text, audio and video.

HEIF can store images encoded with multiple coding formats, for example both SDR and HDR images. HEVC is an image and video encoding format and the default image codec used with HEIF. HEIF files containing HEVC-encoded images are also known as HEIC files. Such files require less storage space than the equivalent quality JPEG.

HEIF files are a special case of the ISO Base Media File Format (ISOBMFF, ISO/IEC 14496-12), first defined in 2001 as a shared part of MP4 and JPEG 2000. Introduced in 2015, it was developed by the Moving Picture Experts Group (MPEG) and is defined as Part 12 within the MPEG-H media suite (ISO/IEC 23008-12).

HEIF was adopted by Apple in 2017 with the introduction of iOS 11.

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๐Ÿ”— Burr conspiracy

๐Ÿ”— United States History ๐Ÿ”— Past Political Scandals and Controversies

The Burr conspiracy was a suspected treasonous cabal of US planters, politicians, and army officers in the early 19th century. The alleged cabal was led by Aaron Burr, the former Vice President of the United States (1801โ€“1805). According to the accusations against him, his goal was to create an independent country in the center of North America including the Southwestern United States and parts of Mexico. Burr's version was that he intended to farm 40,000 acres (160ย km2) in the Texas Territory which had been leased to him by the Spanish Crown.

President Thomas Jefferson ordered Burr arrested and indicted for treason, despite a lack of firm evidence. Burr's true intentions remain unclear to historians; some claim that he intended to take parts of Texas and the Louisiana Purchase for himself, others, that he intended to conquer Mexico, and yet others, that he planned to conquer most of the North American continent. The number of men backing him is also unclear, with accounts varying from fewer than forty to over seven thousand. He was acquitted of treason, but the trial destroyed his already faltering political career.

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๐Ÿ”— Cagot: a persecuted and despised minority found in the west of France

๐Ÿ”— France ๐Ÿ”— Basque

The Cagots (pronouncedย [ka.ษกo]) were a persecuted minority found in the west of France and northern Spain: the Navarrese Pyrenees, Basque provinces, Bรฉarn, Aragรณn, Gascony and Brittany. Their name differed by province and the local language: Cagots, Gรฉzitains, Gahets, and Gafets in Gascony; Agotes, Agotak, and Gafos in Basque country; Capots in Anjou and Languedoc; and Cacons, Cahets, Caqueux, and Caquins in Brittany. Evidence of the group exists back as far as AD 1000.

Cagots were shunned and hated; while restrictions varied by time and place, they were typically required to live in separate quarters in towns, called cagoteries, which were often on the far outskirts of the villages. Cagots were excluded from all political and social rights. They were not allowed to marry non-Cagots, enter taverns, hold cabarets, use public fountains, sell food or wine, touch food in the market, work with livestock, or enter mills. They were allowed to enter a church only by a special door and, during the service, a rail separated them from the other worshippers. Either they were altogether forbidden to partake of the sacrament, or the Eucharist was given to them on the end of a wooden spoon, while a holy water stoup was reserved for their exclusive use. They were compelled to wear a distinctive dress to which, in some places, was attached the foot of a goose or duck (whence they were sometimes called "Canards"). So pestilential was their touch considered that it was a crime for them to walk the common road barefooted or to drink from the same cup as non-Cagots. The Cagots were often restricted to the trades of carpenter, butcher, and rope-maker.

The Cagots were not an ethnic nor a religious group. They spoke the same language as the people in an area and generally kept the same religion as well. Their only distinguishing feature was their descent from families long identified as Cagots. Few consistent reasons were given as to why they were hated; accusations varied from Cagots being cretins, lepers, heretics, cannibals, to simply being intrinsically evil. The Cagots did have a culture of their own, but very little of it was written down or preserved; as a result, almost everything that is known about them relates to their persecution. The repression lasted through the Middle Ages, Renaissance, and Industrial Revolution, with the prejudice fading only in the 19th and 20th centuries.

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๐Ÿ”— Tom Preston-Werner (this page has been deleted)

๐Ÿ”— Biography ๐Ÿ”— Computing ๐Ÿ”— Biography/science and academia

Thomas Preston-Werner (born October 28, 1979) is an American billionaire software developer and entrepreneur. He is an active contributor within the open-source development community, most prominently in the San Francisco Bay Area, where he lives.

He is best known as the founder and former CEO of GitHub, a Git repository web-based hosting service, which he co-founded in 2008 with Chris Wanstrath and PJ Hyett. He resigned from GitHub in 2014 when an internal investigation concluded that he and his wife harassed an employee. Preston-Werner is also the creator of the avatar service Gravatar, the TOML configuration file format and the Semantic Versioning Specification (SemVer)

Preston-Werner lives in San Francisco with his wife Theresa and their sons.

His wife is a former graduate student in cultural anthropology known for her involvement in historical research and social subjects.

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๐Ÿ”— Tuffi

๐Ÿ”— Mammals

Tuffi (born 1946, India โ€“ died 1989, Paris, France) was a female Asian elephant that became famous in West Germany during 1950 when she accidentally fell from the Wuppertal Schwebebahn into the River Wupper underneath.

On 21 July 1950, the circus director Franz Althoff (de) had Tuffi, then four years old, traveled on the suspended monorail in Wuppertal, as a publicity stunt. The elephant trumpeted wildly and ran through the carriage, broke through a window and fell 12 metres (39ย ft) down into the River Wupper, suffering only minor injuries. A panic had broken out in the carriage and some passengers were injured. Althoff helped the elephant out of the water. Both the circus director and the official who had allowed the ride were fined. Tuffi was sold to Cirque Alexis Gruss (fr) in 1968; she died there in 1989.

No photograph of the incident is known; a widely circulated postcard picture is a montage. A building near the location of the incident, between the stations Alter Markt and Adlerbrรผcke, features a painting of Tuffi. A local milk-factory has chosen the name as a brand.

The Wuppertal tourist information keeps an assortment of Tuffi-related souvenirs, local websites show original pictures.

In 1970 Marguerita Eckel and Ernst-Andreas Ziegler published a children's picture book about the incident titled Tuffi und die Schwebebahn (โ€œTuffi and the suspension railwayโ€).

๐Ÿ”— Flexagon

๐Ÿ”— Mathematics ๐Ÿ”— Toys

In geometry, flexagons are flat models, usually constructed by folding strips of paper, that can be flexed or folded in certain ways to reveal faces besides the two that were originally on the back and front.

Flexagons are usually square or rectangular (tetraflexagons) or hexagonal (hexaflexagons). A prefix can be added to the name to indicate the number of faces that the model can display, including the two faces (back and front) that are visible before flexing. For example, a hexaflexagon with a total of six faces is called a hexahexaflexagon.

In hexaflexagon theory (that is, concerning flexagons with six sides), flexagons are usually defined in terms of pats.

Two flexagons are equivalent if one can be transformed to the other by a series of pinches and rotations. Flexagon equivalence is an equivalence relation.

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๐Ÿ”— Sand Theft

๐Ÿ”— Crime ๐Ÿ”— Mining

Sand theft or unauthorised or illegal sand mining leads to a widely unknown global example of natural and non-renewable resource depletion problem comparable in extent to global water scarcity. Beach theft is illegal removal of large quantities of sand from a beach leading to full or partial disappearance of the beach.

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