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🔗 United States/U.S. Government 🔗 United States

This article deals with the activities of the Central Intelligence Agency of the Federal government of the United States, that violate human rights.

🔗 Mathematics 🔗 Biology 🔗 Physics 🔗 Plants

Tendril perversion, often referred to in context as simply perversion, is a geometric phenomenon found in helical structures such as plant tendrils, in which a helical structure forms that is divided into two sections of opposite chirality, with a transition between the two in the middle. A similar phenomenon can often be observed in kinked helical cables such as telephone handset cords.

The phenomenon was known to Charles Darwin, who wrote in 1865,

A tendril ... invariably becomes twisted in one part in one direction, and in another part in the opposite direction... This curious and symmetrical structure has been noticed by several botanists, but has not been sufficiently explained.

The term "tendril perversion" was coined by Goriely and Tabor in 1998 based on the word perversion found in the 19th Century science literature. "Perversion" is a transition from one chirality to another and was known to James Clerk Maxwell, who attributed it to the topologist J. B. Listing.

Tendril perversion can be viewed as an example of spontaneous symmetry breaking, in which the strained structure of the tendril adopts a configuration of minimum energy while preserving zero overall twist.

Tendril perversion has been studied both experimentally and theoretically. Gerbode et al. have made experimental studies of the coiling of cucumber tendrils. A detailed study of a simple model of the physics of tendril perversion was made by MacMillen and Goriely in the early 2000s. Liu et al. showed in 2014 that "the transition from a helical to a hemihelical shape, as well as the number of perversions, depends on the height to width ratio of the strip's cross-section."

Generalized tendril perversions were put forward by Silva et al., to include perversions that can be intrinsically produced in elastic filaments, leading to a multiplicity of geometries and dynamical properties.

🔗 Biography 🔗 Soviet Union 🔗 Russia 🔗 Biography/sports and games 🔗 Russia/sports and games in Russia 🔗 Armenia 🔗 Underwater diving 🔗 Swimming

Shavarsh Vladimiri (Vladimirovich) Karapetyan (Armenian: Շավարշ Կարապետյան; born May 19, 1953) is a retired former Soviet finswimmer, best known for saving the lives of 20 people in a 1976 incident in Yerevan.

🔗 Time 🔗 Moon

A blue moon is an additional full moon that appears in a subdivision of a year: either the third of four full moons in a season, or a second full moon in a month of the common calendar.

The phrase in modern usage has nothing to do with the actual color of the Moon, although a visually blue Moon (the Moon appearing with a bluish tinge) may occur under certain atmospheric conditions – for instance, if volcanic eruptions or fires release particles in the atmosphere of just the right size to preferentially scatter red light.

🔗 Medicine 🔗 Psychology 🔗 Physiology

Biphasic sleep (or diphasic, bimodal or bifurcated sleep) is the practice of sleeping during two periods over the course of 24 hours, while polyphasic sleep refers to sleeping multiple times – usually more than two. Each of these is in contrast to monophasic sleep, which is one period of sleep within 24 hours. Segmented sleep and divided sleep may refer to polyphasic or biphasic sleep, but may also refer to interrupted sleep, where the sleep has one or several shorter periods of wakefulness. A common form of biphasic or polyphasic sleep includes a nap, which is a short period of sleep, typically taken between the hours of 9 am and 9 pm as an adjunct to the usual nocturnal sleep period. Nowadays, the definition of polyphasic sleep is any sleep schedule with at least two sleeps per day, to distinguish it from monophasic sleep, which only has one sleep per day.

The term polyphasic sleep was first used in the early 20th century by psychologist J. S. Szymanski, who observed daily fluctuations in activity patterns (see Stampi 1992). It does not imply any particular sleep schedule. The circadian rhythm disorder known as irregular sleep-wake syndrome is an example of polyphasic sleep in humans. Polyphasic sleep is common in many animals, and is believed to be the ancestral sleep state for mammals, although simians are monophasic.

The term polyphasic sleep is also used by an online community that experiments with alternative sleeping schedules to achieve more time awake each day. However, researchers such as Piotr Woźniak warn that such forms of sleep deprivation are not healthy. While many claim that polyphasic sleep was widely used by some polymaths and prominent people such as Leonardo da Vinci, Napoleon, and Nikola Tesla, there are few reliable sources supporting that view.

🔗 United States 🔗 Books 🔗 Reference works 🔗 English Language

The New Oxford American Dictionary (NOAD) is a single-volume dictionary of American English compiled by American editors at the Oxford University Press.

NOAD is based upon the New Oxford Dictionary of English (NODE), published in the United Kingdom in 1998, although with substantial editing, additional entries, and the inclusion of illustrations. It is based on a corpus linguistics analysis of Oxford's 200 million word database of contemporary American English.

NOAD includes a diacritical respelling scheme to convey pronunciations, as opposed to the Gimson phonemic IPA system that is used in NODE.

🔗 Biography 🔗 Business 🔗 England 🔗 Invention 🔗 Professional sound production

Kane Kramer is a British inventor and businessman. He is credited with the initial invention of the digital audio player, in 1979.

🔗 Mathematics

The Erdős number (Hungarian: [ˈɛrdøːʃ]) describes the "collaborative distance" between mathematician Paul Erdős and another person, as measured by authorship of mathematical papers. The same principle has been applied in other fields where a particular individual has collaborated with a large and broad number of peers.

🔗 Writing systems 🔗 Archaeology 🔗 Visual arts

The Phaistos Disc (also spelled Phaistos Disk, Phaestos Disc) is a disk of fired clay from the Minoan palace of Phaistos on the island of Crete, possibly dating to the middle or late Minoan Bronze Age (second millennium B.C.). The disk is about 15 cm (5.9 in) in diameter and covered on both sides with a spiral of stamped symbols. Its purpose and meaning, and even its original geographical place of manufacture, remain disputed, making it one of the most famous mysteries of archaeology. This unique object is now on display at the archaeological museum of Heraklion.

The disc was discovered in 1908 by the Italian archaeologist Luigi Pernier in the Minoan palace-site of Phaistos, and features 241 tokens, comprising 45 distinct signs, which were apparently made by pressing hieroglyphic "seals" into a disc of soft clay, in a clockwise sequence spiraling toward the center of the disk.

The Phaistos Disc captured the imagination of amateur and professional archaeologists, and many attempts have been made to decipher the code behind the disc's signs. While it is not clear that it is a script, most attempted decipherments assume that it is; most additionally assume a syllabary, others an alphabet or logography. Attempts at decipherment are generally thought to be unlikely to succeed unless more examples of the signs are found, as it is generally agreed that there is not enough context available for a meaningful analysis.

Although the Phaistos Disc is generally accepted as authentic by archaeologists, a few scholars believe that the disc is a forgery or a hoax.

🔗 Mass surveillance 🔗 Computing 🔗 Internet culture 🔗 Philosophy 🔗 Cryptography 🔗 Cryptography/Computer science 🔗 Numismatics 🔗 Sociology 🔗 Numismatics/Cryptocurrency 🔗 Computing/Computer Security 🔗 Philosophy/Anarchism 🔗 Anarchism

Crypto-anarchism (or crypto-anarchy) is a political ideology focusing on protection of privacy, political freedom and economic freedom, the adherents of which use cryptographic software for confidentiality and security while sending and receiving information over computer networks.

By using cryptographic software, the association between the identity of a certain user or organization and the pseudonym they use is made difficult to find, unless the user reveals the association. It is difficult to say which country's laws will be ignored, as even the location of a certain participant is unknown. However, participants may in theory voluntarily create new laws using smart contracts or, if the user is pseudonymous, depend on online reputation.