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🔗 Mathematics

The hairy ball theorem of algebraic topology (sometimes called the hedgehog theorem in Europe) states that there is no nonvanishing continuous tangent vector field on even-dimensional n-spheres. For the ordinary sphere, or 2‑sphere, if f is a continuous function that assigns a vector in R³ to every point p on a sphere such that f(p) is always tangent to the sphere at p, then there is at least one p such that f(p) = 0. The theorem was first stated by Henri Poincaré in the late 19th century, and first proven in 1912 by Luitzen Egbertus Jan Brouwer.

The theorem has been expressed colloquially as "you can't comb a hairy ball flat without creating a cowlick" or "you can't comb the hair on a coconut".

🔗 Engineering

Ephemeralization, a term coined by R. Buckminster Fuller in 1938, is the ability of technological advancement to do "more and more with less and less until eventually you can do everything with nothing," that is, an accelerating increase in the efficiency of achieving the same or more output (products, services, information, etc.) while requiring less input (effort, time, resources, etc.). Fuller's vision was that ephemeralization will result in ever-increasing standards of living for an ever-growing population despite finite resources. The concept has been embraced by those who argue against Malthusian philosophy. The subsequently coined economics term "dematerialization" refers to essentially the same concept as also does eco-economic decoupling.

🔗 Biology

The thermal grill illusion is a sensory illusion originally demonstrated in 1896 by the Swedish physician Torsten Thunberg. The illusion is created by an interlaced grill of warm (e.g., 40°C/104°F) and cool (20°C/68°F) bars. When someone presses a hand against the grill, they experience the illusion of burning heat. But if the person presses against only a cool bar, only coolness is experienced; if the person presses against only a warm bar, only warmth is experienced.

Researchers have used the illusion to demonstrate that burning pain sensation is in fact a mixture of both cold and heat pain and that it is only the inhibition of the cold pain "channel" that reveals the heat component.

The illusion is demonstrated by positioning the middle finger in cold water and the ring and index fingers in warm water. Due to shortcomings in the body map - multisensory representation of the body - and this particular sensory input configuration, the brain is tricked into thinking the middle finger is in the warm water and the index and ring fingers in cold water.

In an fMRI experiment of the illusion, researchers recently observed an activation of the thalamus not seen for control stimuli. Also, activity in a portion of the right mid/anterior insula correlated with the perceived unpleasantness of the illusion.

🔗 Human rights 🔗 China 🔗 Islam 🔗 Central Asia 🔗 Correction and Detention Facilities 🔗 2010s

The Xinjiang internment camps are internment camps operated by the government of Xinjiang and the Chinese Communist Party Provincial Standing Committee. Human Rights Watch says that they have been used to indoctrinate Uyghurs since 2017 as part of a "Strike Hard Campaign Against Violent Terrorism", a policy announced in 2014 after the May 2014 Ürümqi attack. Xinjiang internment camps have been described as "the most extreme example of China's inhumane policies against Uighurs". They were established as what are officially called vocational education and training centers by the government of the People's Republic of China. According to researcher Adrian Zenz, mass internments peaked in 2018 and have abated somewhat since then, with officials shifting focus towards forced labor programs. Since then, the Chinese government has claimed the centers have been closed. Individuals in the camps have been shifted into the formal penal system, with remaining camps being converted into prisons or factories using forced labor.

The camps were established in 2017 by the administration of CCP general secretary Xi Jinping. Between 2017 and 2021 operations were led by CCP Politburo member and Xinjiang Party secretary Chen Quanguo. The camps are reportedly operated outside the Chinese legal system; many Uyghurs have reportedly been interned without trial and no charges have been levied against them (held in administrative detention). Local authorities are reportedly holding hundreds of thousands of Uyghurs in these camps as well as members of other ethnic minority groups in China, for the stated purpose of countering extremism and terrorism and promoting social integration.

In July 2019, UN ambassadors of 37 countries, predominantly in Africa and Asia, signed a joint letter to the United Nations Human Rights Council defending China's policies in Xinjiang while 22 countries, mostly in North America and Europe, opposed them. In October 2020, 16 countries that defended China's policies in 2019 did not do so.

The internment of Uyghurs and other Turkic Muslims in the camps constituted the largest-scale arbitrary detention of ethnic and religious minorities since World War II. In 2020, it was estimated that Chinese authorities may have detained up to 1.8 million people, mostly Uyghurs but also including Kazakhs, Kyrgyz and other ethnic Turkic Muslims, Christians, as well as some foreign citizens including Kazakhstanis, in these secretive internment camps located throughout the region. In September 2020, the Australian Strategic Policy Institute (ASPI) reported in its Xinjiang Data Project that construction of camps continued despite government claims that their function was winding down. There have been comparisons between the Xinjiang camps and the Cultural Revolution.

🔗 Technology 🔗 Physics 🔗 Physics/Acoustics

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

🔗 United States 🔗 Africa 🔗 African diaspora 🔗 United States/Kentucky 🔗 Africa/Liberia

Kentucky in Africa was a colony in present-day Montserrado County, Liberia, founded in 1828 and settled by American free people of color, many of them former slaves. A state affiliate of the American Colonization Society, the Kentucky State Colonization Society raised money to transport people of color from Kentucky—freeborn volunteers as well as enslaved individuals set free on the condition that they leave the United States for Liberia. The Kentucky society bought a 40-square-mile (100 km²) site along the Saint Paul River (quite near the site of the present-day capital city of Monrovia) and named it Kentucky in Africa. Clay-Ashland. named after Henry Clay's Ashland Plantation, was the colony's primary settlement.

Notable residents of Kentucky in Africa include Alfred Francis Russell, the 10th President of Liberia, and William D. Coleman, the 13th President of Liberia, whose family settled in Clay-Ashland after emigrating from Fayette County, Kentucky.

Kentucky in Africa was annexed by Liberia in about 1847.

🔗 Middle Ages 🔗 Middle Ages/History 🔗 Celts 🔗 Writing systems 🔗 Ireland 🔗 Medieval Scotland

Ogham (Modern Irish: [ˈoː(ə)mˠ]; Middle Irish: ogum, ogom, later ogam [ˈɔɣəmˠ]) is an Early Medieval alphabet used primarily to write the early Irish language (in the "orthodox" inscriptions, 4th to 6th centuries AD), and later the Old Irish language (scholastic ogham, 6th to 9th centuries). There are roughly 400 surviving orthodox inscriptions on stone monuments throughout Ireland and western Britain, the bulk of which are in southern Munster. The largest number outside Ireland are in Pembrokeshire, Wales.

The vast majority of the inscriptions consist of personal names.

According to the High Medieval Bríatharogam, the names of various trees can be ascribed to individual letters. For this reason, ogam is sometimes known as the Celtic tree alphabet.

The etymology of the word ogam or ogham remains unclear. One possible origin is from the Irish og-úaim 'point-seam', referring to the seam made by the point of a sharp weapon.

🔗 Education

The Dreyfus model of skill acquisition is a model of how learners acquire skills through formal instruction and practicing, used in the fields of education and operations research. Brothers Stuart and Hubert Dreyfus proposed the model in 1980 in an 18-page report on their research at the University of California, Berkeley, Operations Research Center for the United States Air Force Office of Scientific Research. The model proposes that a student passes through five distinct stages and was originally determined as: novice, competence, proficiency, expertise, and mastery.

🔗 California 🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Military history/World War II 🔗 Paranormal 🔗 California/Southern California

The Battle of Los Angeles, also known as the Great Los Angeles Air Raid, is the name given by contemporary sources to a rumored attack on the mainland United States by Imperial Japan and the subsequent anti-aircraft artillery barrage which took place from late 24 February to early 25 February 1942, over Los Angeles, California. The incident occurred less than three months after the U.S. entered World War II in response to the Imperial Japanese Navy's surprise attack on Pearl Harbor, and one day after the bombardment of Ellwood near Santa Barbara on 23 February. Initially, the target of the aerial barrage was thought to be an attacking force from Japan, but speaking at a press conference shortly afterward, Secretary of the Navy Frank Knox called the purported attack a "false alarm". Newspapers of the time published a number of reports and speculations of a cover-up.

When documenting the incident in 1949, the United States Coast Artillery Association identified a meteorological balloon sent aloft at 1:00 am as having "started all the shooting" and concluded that "once the firing started, imagination created all kinds of targets in the sky and everyone joined in". In 1983, the U.S. Office of Air Force History attributed the event to a case of "war nerves" triggered by a lost weather balloon and exacerbated by stray flares and shell bursts from adjoining batteries.

🔗 Technology 🔗 Computing 🔗 France 🔗 Computing/Computer hardware 🔗 Telecommunications 🔗 Popular Culture 🔗 Computing/Networking

Minitel, officially known as TELETEL, was an interactive videotex online service accessible through telephone lines. It was the world's first and most successful mass-market online service prior to the World Wide Web. It was developed in Cesson-Sévigné, Brittany, by government-owned France Télécom.

The service was initially launched on an experimental basis in July 1980 in Saint-Malo and extended to other regions in late 1980. It was commercially introduced throughout France in 1982 by the Postes, Télégraphes et Téléphones (PTT), since 1991, divided into France Télécom and La Poste. From its inception, users were able to make online purchases, book train tickets, access business information services, search the telephone directory, maintain a mailbox, and utilize chat functionalities similar to those now supported by the World Wide Web.

In February 2009, France Télécom reported that the Minitel network still maintained 10 million monthly connections. The service was discontinued by France Télécom on 30 June 2012.