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π Musaeum Clausum
Musaeum Clausum (Latin for Sealed Museum), also known as Bibliotheca abscondita, is a tract written by Sir Thomas Browne which was first published posthumously in 1684. The tract contains short sentence descriptions of supposed, rumoured or lost books, pictures, and objects. The subtitle describes the tract as an inventory of remarkable books, antiquities, pictures and rarities of several kinds, scarce or never seen by any man now living. Its date is unknown: however, an event from the year 1673 is cited.
Like his Pseudodoxia Epidemica, Musaeum Clausum is a catalogue of doubts and queries, only this time, in a style which anticipates the 20th-century Argentinian short-story writer Jorge Luis Borges, who once declared: "To write vast books is a laborious nonsense; much better is to offer a summary as if those books actually existed."
Browne however was not the first author to engage in such fantasy. The French author Rabelais, in his epic Gargantua and Pantagruel, also penned a list of imaginary and often obscene book titles in his "Library of Pantagruel", an inventory which Browne himself alludes to in his Religio Medici.
As the 17th-century Scientific Revolution progressed the popularity and growth of antiquarian collections, those claiming to house highly improbable items grew. Browne was an avid collector of antiquities and natural specimens, possessing a supposed unicorn's horn, presented to him by Arthur Dee. Browne's eldest son Edward visited the famous scholar Athanasius Kircher, founder of the Museo Kircherano at Rome in 1667, whose exhibits included an engine for attempting perpetual motion and a speaking head, which Kircher called his Oraculum Delphinium. He wrote to his father of his visit to the Jesuit priest's "closet of rarities".
The sheer volume of book-titles, pictures and objects listed in Musaeum Clausum is testimony to Browne's fertile imagination. However, his major editors, Simon Wilkin in the nineteenth century (1834) and Sir Geoffrey Keynes in the twentieth (1924), summarily dismissed it. Keynes considered its humour too erudite and "not to everyone's taste".
Browne's miscellaneous tract may also be read as a parody of the rising trend of private museum collections with their curios of doubtful origin, and perhaps also of publications such as the so-called Museum Hermeticum (1678), one of the last great anthologies of alchemical literature, with their divulging of near common-place alchemical concepts and symbols.
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- "Musaeum Clausum" | 2021-09-09 | 17 Upvotes 1 Comments
π Bang Bang Control
In control theory, a bangβbang controller (2 step or onβoff controller), also known as a hysteresis controller, is a feedback controller that switches abruptly between two states. These controllers may be realized in terms of any element that provides hysteresis. They are often used to control a plant that accepts a binary input, for example a furnace that is either completely on or completely off. Most common residential thermostats are bangβbang controllers. The Heaviside step function in its discrete form is an example of a bangβbang control signal. Due to the discontinuous control signal, systems that include bangβbang controllers are variable structure systems, and bangβbang controllers are thus variable structure controllers.
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- "Bang Bang Control" | 2016-04-07 | 30 Upvotes 24 Comments
π World-systems theory
World-systems theory (also known as world-systems analysis or the world-systems perspective) is a multidisciplinary, macro-scale approach to world history and social change which emphasizes the world-system (and not nation states) as the primary (but not exclusive) unit of social analysis.
"World-system" refers to the inter-regional and transnational division of labor, which divides the world into core countries, semi-periphery countries, and the periphery countries. Core countries focus on higher skill, capital-intensive production, and the rest of the world focuses on low-skill, labor-intensive production and extraction of raw materials. This constantly reinforces the dominance of the core countries. Nonetheless, the system has dynamic characteristics, in part as a result of revolutions in transport technology, and individual states can gain or lose their core (semi-periphery, periphery) status over time. This structure is unified by the division of labour. It is a world-economy rooted in a capitalist economy. For a time, certain countries become the world hegemon; during the last few centuries, as the world-system has extended geographically and intensified economically, this status has passed from the Netherlands, to the United Kingdom and (most recently) to the United States.
World-systems theory has been examined by many political theorists and sociologists to explain the reasons for the rise and fall of nations, income inequality, social unrest, and imperialism.
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- "World-systems theory" | 2014-07-12 | 51 Upvotes 8 Comments
π Wikipedia chooses Lua as its new template/macro language
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- "Wikipedia chooses Lua as its new template/macro language " | 2012-01-31 | 25 Upvotes 1 Comments
π Hybridogenesis in water frogs
The fertile hybrids of European water frogs (genus Pelophylax) reproduce by hybridogenesis (hemiclonally). This means that during gametogenesis, they discard the genome of one of the parental species and produce gametes of the other parental species (containing a genome not recombined with the genome of the first parental species). The first parental genome is restored by fertilization of these gametes with gametes from the first species (sexual host). In all-hybrid populations of the edible frog Pelophylax kl. esculentus, however, triploid hybrids provide this missing genome.
Because half of the genome is transmitted to the next generation clonally (not excluded unrecombined intact genome), and only the other half sexually (recombined genome of the sexual host), the hybridogenesis is a hemiclonal mode of reproduction.
For example, the edible frog Pelophylax kl. esculentus (mostly RL genome), which is a hybridogenetic hybrid of the marsh frog P. ridibundus (RR) and the pool frog P. lessonae (LL), usually excludes the lessonae genome (L) and generates gametes of the P. ridibundus (R). In other words, edible frogs produce gametes of marsh frogs.
The hybrid populations are propagated, however, not by the above primary hybridisations, but predominantly by backcrosses with one of the parental species they coexist (live in sympatry) with (see below in the middle).
Since the hybridogenetic hybrids require another taxon as sexual host to reproduce, usually one of the parental species, they are called kleptons (with "kl." in scientific names).
There are three known hybridogenetic hybrids of the European water frogs:
- edible frog Pelophylax kl. esculentus (usually genotype RL):
pool frog P. lessonae (LL) Γ P. ridibundus (RR) - Graf's hybrid frog Pelophylax kl. grafi (PR):
Perez's frog P. perezi (PP) Γ P. ridibundus (RR) or
Perez's frog P. perezi (PP) Γ edible frog P. kl. esculentus (RE)
(it is unclear which one crossing was the primary hybridisation) - Italian edible frog Pelophylax kl. hispanicus (RB):
Italian pool frog P. bergeri (BB) Γ P. ridibundus (RR)
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- "Hybridogenesis in water frogs" | 2019-05-26 | 21 Upvotes 1 Comments
π _NSAKEY
_NSAKEY was a variable name discovered in an operating system from Microsoft in 1999. The variable contained a 1024-bit public key; such keys are used in cryptography for encryption and authentication. Due to the name it was speculated that the key was owned by the United States National Security Agency (the NSA) which would allow the intelligence agency to subvert any Windows user's security. Microsoft denied the speculation and said that the key's name came from the NSA being the technical review authority for U.S. cryptography export controls.
The key was discovered in a Windows NT 4 Service Pack 5 (which had been released unstripped of its symbolic debugging data) in August 1999 by Andrew D. Fernandes of Cryptonym Corporation.
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- "_NSAKEY" | 2022-01-29 | 15 Upvotes 1 Comments
- "_NSAKEY" | 2020-01-14 | 254 Upvotes 109 Comments
- "Microsoft _NSAKEY" | 2019-01-03 | 18 Upvotes 2 Comments
- "_NSAKEY (1999)" | 2013-07-12 | 8 Upvotes 10 Comments
π Sex drive-in
A sex drive-in or sex box is a car garage (or similarly shielded location) that is designed to allow prostitution to take place using cars, and can be found in a few countries in Europe. Generally the facilities are created by local authorities to put some control on where prostitution occurs and to provide increased safety.
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- "Sex drive-in" | 2020-02-26 | 35 Upvotes 18 Comments
π Hedy Lamarr
Hedy Lamarr (), born Hedwig Eva Maria Kiesler (November 9, 1914Β β January 19, 2000), was an Austrian-born American actress, inventor and film producer. She was part of 30 films in an acting career spanning 28 years, and co-invented an early version of frequency-hopping spread spectrum.
After a brief early film career in Czechoslovakia, including the controversial Ecstasy (1933), she fled from her husband, a wealthy Austrian ammunition manufacturer, and secretly moved to Paris. Traveling to London, she met Louis B. Mayer, head of Metro-Goldwyn-Mayer (MGM) studio, who offered her a movie contract in Hollywood, where he began promoting her as the "world's most beautiful woman".
She became a star with her performance in Algiers (1938), her first film made in the United States. Her MGM films include Lady of the Tropics (1939), Boom Town (1940), H.M. Pulham, Esq. (1941), and White Cargo (1942). Dismayed with her MGM contract, Lamarr co-founded a new production studio and starred in its films including The Strange Woman (1946), and Dishonored Lady (1947). Her greatest success was as Delilah in Cecil B. DeMille's Samson and Delilah (1949). She also acted on television before the release of her final film, The Female Animal (1958). She was honored with a star on the Hollywood Walk of Fame in 1960.
At the beginning of World War II, Lamarr and composer George Antheil developed a radio guidance system for Allied torpedoes, intended to use frequency-hopping spread spectrum technology to defeat the threat of jamming by the Axis powers. She also helped to improve aviation designs for Howard Hughes while they dated during the war. Although the US Navy did not adopt Lamarr and Antheil's invention until 1957, various spread-spectrum techniques are incorporated into Bluetooth technology and are similar to methods used in legacy versions of Wi-Fi. Recognition of the value of their work resulted in the pair being posthumously inducted into the National Inventors Hall of Fame in 2014.
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- "Hedy Lamarr" | 2020-02-12 | 38 Upvotes 18 Comments
- "Hedy Lamarr, femme fatale and inventor of spread spectrum communications " | 2010-05-21 | 65 Upvotes 8 Comments
π The Expert at the Card Table: The Classic Treatise on Card Manipulation
The Expert at the Card Table, originally titled Artifice, Ruse and Subterfuge at the Card Table: A Treatise on the Science and Art of Manipulating Cards, often referred to simply as Erdnase, is an extensive book on the art of sleight of hand published in 1902 by S. W. Erdnase, a pseudonymous author whose identity has remained a mystery for over a century. As a detailed manual of card sharps, the book is considered to be one of the most influential works on magic or conjuring with cards.
The Expert at the Card Table is the most famous, the most carefully studied book ever published on the art of manipulating cards at gaming tables."
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- "The Expert at the Card Table: The Classic Treatise on Card Manipulation" | 2015-01-28 | 76 Upvotes 20 Comments
π Low-Background Steel
Low-background steel is any steel produced prior to the detonation of the first nuclear bombs in the 1940s and 1950s. With the Trinity test and the nuclear bombings of Hiroshima and Nagasaki in 1945, and then subsequent nuclear weapons testing during the early years of the Cold War, background radiation levels increased across the world. Modern steel is contaminated with radionuclides because its production uses atmospheric air. Low-background steel is so-called because it does not suffer from such nuclear contamination. This steel is used in devices that require the highest sensitivity for detecting radionuclides.
The primary source of low-background steel is ships that were constructed before the Trinity test, most famously the scuttled German World War I warships in Scapa Flow.
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- "Low-Background Steel" | 2021-10-24 | 27 Upvotes 3 Comments
- "Low-Background Steel" | 2020-07-19 | 359 Upvotes 107 Comments
- "Low-background steel" | 2016-06-19 | 159 Upvotes 28 Comments
- "Low-background Steel" | 2013-10-25 | 30 Upvotes 13 Comments