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π Calisthenics
Calisthenics (American English) or callisthenics (British English) is a form of exercise consisting of a variety of movements that exercise large muscle groups (gross motor movements), such as running, standing, grasping, pushing, etc. These exercises are often performed rhythmically and with minimal equipment, as bodyweight exercises. They are intended to increase strength, fitness, and flexibility, through movements such as pulling, pushing, bending, jumping, or swinging, using one's body weight for resistance. Calisthenics can provide the benefits of muscular and aerobic conditioning, in addition to improving psychomotor skills such as balance, agility, and coordination.
Urban calisthenics is a form of street workout; calisthenics groups perform exercise routines in urban areas. Individuals and groups train to perform advanced calisthenics skills such as muscle-ups, levers, and various freestyle moves such as spins and flips.
Sports teams and military units often perform leader-directed group calisthenics as a form of synchronized physical training (often including a customized "call and response" routine) to increase group cohesion and discipline. Calisthenics is also popular as a component of physical education in primary and secondary schools over much of the globe.
In addition to general fitness, calisthenic exercises are often used as baseline physical evaluations for military organizations around the world. Two examples are the U.S. Army Physical Fitness Test and the U.S.M.C. Physical Fitness Test.
Discussed on
- "Calisthenics" | 2020-10-04 | 13 Upvotes 3 Comments
π User: Junnn11
Arthropod enthusiast, mainly focus on Panarthropod head problem, phylogeny across arthropod subphyla and stem lineage, basal chelicerates, dinocaridids and lobopodians. Sometime drawing stuff, not so well in english, mainly active at Japanese Wikipedia.
Japanese: ε©η¨θ :Junnn11
Commons: User:Junnn11
Twitter: ni075
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- "User: Junnn11" | 2023-04-19 | 747 Upvotes 101 Comments
π Universal Disk Format
Universal Disk Format (UDF) is a profile of the specification known as ISO/IEC 13346 and ECMA-167 and is an open vendor-neutral file system for computer data storage for a broad range of media. In practice, it has been most widely used for DVDs and newer optical disc formats, supplanting ISO 9660. Due to its design, it is very well suited to incremental updates on both recordable and (re)writable optical media. UDF is developed and maintained by the Optical Storage Technology Association (OSTA).
Normally, authoring software will master a UDF file system in a batch process and write it to optical media in a single pass. But when packet writing to rewritable media, such as CD-RW, UDF allows files to be created, deleted and changed on-disc just as a general-purpose filesystem would on removable media like floppy disks and flash drives. This is also possible on write-once media, such as CD-R, but in that case the space occupied by the deleted files cannot be reclaimed (and instead becomes inaccessible).
Multi-session mastering is also possible in UDF, though some implementations may be unable to read disks with multiple sessions.
Discussed on
- "Universal Disk Format" | 2013-01-20 | 10 Upvotes 10 Comments
π Salmonella-in-Eggs Controversy
The salmonella-in-eggs controversy was a political controversy in the United Kingdom caused by the Parliamentary Under-Secretary of State for Health, Edwina Currie's claims that "most of the egg production in this country, sadly, is now affected with salmonella" in 1988. These claims led to a 60 percent decline in egg sales over the next few weeks, and angered both politicians and those in the egg production industry. Currie's statement also resulted in the destruction of around 400 million eggs and the slaughter of around 4 million hens. The controversy dominated Currie's tenure as Parliamentary Under-Secretary of State for Health and resulted in her resignation two weeks later.
Discussed on
- "Salmonella-in-Eggs Controversy" | 2023-02-22 | 55 Upvotes 73 Comments
π Nash equilibrium
In game theory, the Nash equilibrium, named after the mathematician John Forbes Nash Jr., is a proposed solution of a non-cooperative game involving two or more players in which each player is assumed to know the equilibrium strategies of the other players, and no player has anything to gain by changing only their own strategy.
In terms of game theory, if each player has chosen a strategy, and no player can benefit by changing strategies while the other players keep theirs unchanged, then the current set of strategy choices and their corresponding payoffs constitutes a Nash equilibrium.
Stated simply, Alice and Bob are in Nash equilibrium if Alice is making the best decision she can, taking into account Bob's decision while his decision remains unchanged, and Bob is making the best decision he can, taking into account Alice's decision while her decision remains unchanged. Likewise, a group of players are in Nash equilibrium if each one is making the best decision possible, taking into account the decisions of the others in the game as long as the other parties' decisions remain unchanged.
Nash showed that there is a Nash equilibrium for every finite game: see further the article on strategy.
Discussed on
- "Nash equilibrium" | 2018-10-11 | 20 Upvotes 6 Comments
π Mills' constant
In number theory, Mills' constant is defined as the smallest positive real number A such that the floor function of the double exponential function
is a prime number, for all natural numbers n. This constant is named after William H. Mills who proved in 1947 the existence of A based on results of Guido Hoheisel and Albert Ingham on the prime gaps. Its value is unknown, but if the Riemann hypothesis is true, it is approximately 1.3063778838630806904686144926... (sequence A051021 in the OEIS).
Discussed on
- "Mills' constant" | 2015-02-15 | 44 Upvotes 20 Comments
π Xeer
Xeer (pronounced [Δ§eΛr]) is the traditional legal system of Somalia, and one of the three systems from which formal Somali law draws its inspiration, the others being civil law and Islamic law. It is believed to pre-date Islam, although it was influenced by Islam and retains many of the faith's conservative elements. Under this system, elders, known as the xeer begti serve as mediator judges and help settle court cases, taking precedent and custom into account. Xeer is polycentric in that different groups within Somali society have different interpretations of xeer.
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- "Xeer" | 2014-05-13 | 246 Upvotes 117 Comments
π DempsterβShafer theory
The theory of belief functions, also referred to as evidence theory or DempsterβShafer theory (DST), is a general framework for reasoning with uncertainty, with understood connections to other frameworks such as probability, possibility and imprecise probability theories. First introduced by Arthur P. Dempster in the context of statistical inference, the theory was later developed by Glenn Shafer into a general framework for modeling epistemic uncertaintyβa mathematical theory of evidence. The theory allows one to combine evidence from different sources and arrive at a degree of belief (represented by a mathematical object called belief function) that takes into account all the available evidence.
In a narrow sense, the term DempsterβShafer theory refers to the original conception of the theory by Dempster and Shafer. However, it is more common to use the term in the wider sense of the same general approach, as adapted to specific kinds of situations. In particular, many authors have proposed different rules for combining evidence, often with a view to handling conflicts in evidence better. The early contributions have also been the starting points of many important developments, including the transferable belief model and the theory of hints.
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- "DempsterβShafer theory" | 2015-03-20 | 42 Upvotes 13 Comments
π Ichi-Fuji, ni-taka, san-nasubi
In Japanese culture, a hatsuyume (Japanese: εε€’) is the first dream one has in the new year. Traditionally, the contents of such a dream would foretell the luck of the dreamer in the ensuing year. In Japan, the night of December 31 was often passed without sleeping, so the hatsuyume is often experienced during the night of January 1; the day after the night of the "first dream" is also known as the hatsuyume. This day is January 2 in the Gregorian calendar, but was different in the traditional Japanese calendar.
It is considered to be particularly good luck to dream of Mount Fuji, a hawk, and an eggplant. This belief has been in place since the early Edo period but there are various theories regarding the origins as to why this particular combination was considered to be auspicious. One theory suggests that this combination is lucky because Mount Fuji is Japan's highest mountain, the hawk is a clever and strong bird, and the word for eggplant (θε, nasu or nasubi) suggests achieving something great (ζγ nasu). Another theory suggests that this combination arose because Mount Fuji, falconry, and early eggplants were favorites of the shΕgun Tokugawa Ieyasu.
Although this superstition is well known in Japan, often memorized in the form ichi-Fuji, ni-taka, san-nasubi (δΈε―士γδΊι·ΉγδΈθε; 1. Fuji, 2. Hawk, 3. Eggplant), the continuation of the list is not as well known. The continuation is yon-sen, go-tabako, roku-zatΕ (εζγδΊη θγε εΊ§ι ; 4. Fan, 5. Tobacco, 6. Blind acupressurer). The origins of this trio are less well known, and it is unclear whether they were added after the original three or whether the list of six originated at the same time.
π Steam Cannon
A steam cannon is a cannon that launches a projectile using only heat and water, or using a ready supply of high-pressure steam from a boiler. The first steam cannon was designed by Archimedes during the Siege of Syracuse. Leonardo Da Vinci was also known to have designed one (see the Architonnerre).
The early device would consist of a large metal tube, preferably copper due to its high thermal conductivity, which would be placed in a furnace. One end of the tube would be capped and the other loaded with a projectile. Once the tube reached a high enough temperature, a small amount of water would be injected in behind the projectile. In theory, Leonardo da Vinci believed, the water would rapidly expand into vapour, blasting the projectile out the front of the barrel.
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- "Steam Cannon" | 2019-10-28 | 37 Upvotes 24 Comments