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🔗 Oceans 🔗 Polymers

The Indian Ocean garbage patch, discovered in 2010, is a gyre of marine litter suspended in the upper water column of the central Indian Ocean, specifically the Indian Ocean Gyre, one of the five major oceanic gyres. The patch does not appear as a continuous debris field. As with other patches in each of the five oceanic gyres, the plastics in it break down to ever smaller particles, and to constituent polymers. As with the other patches, the field constitutes an elevated level of pelagic plastics, chemical sludge, and other debris; primarily particles that are invisible to the naked eye. The concentration of particle debris has been estimated to be approximately 10,000 particles per square kilometer.

A similar patch of floating plastic debris in the Pacific Ocean, the Great Pacific garbage patch, was predicted in 1985, and discovered in 1997 by Charles J. Moore as he passed through the North Pacific Gyre on his return from the Transpacific Yacht Race. The North Atlantic garbage patch was discovered in 2010.

🔗 Computing 🔗 Computing/Software 🔗 Numismatics 🔗 Software 🔗 Software/Computing 🔗 Numismatics/Cryptocurrency 🔗 Cryptocurrency 🔗 Computing/Computer Security

Namecoin (Symbol: ℕ or NMC) is a cryptocurrency originally forked from bitcoin software. It is based on the code of bitcoin and uses the same proof-of-work algorithm. Like bitcoin, it is limited to 21 million coins.

Namecoin can store data within its own blockchain transaction database. The original proposal for Namecoin called for Namecoin to insert data into bitcoin's blockchain directly. Anticipating scaling difficulties with this approach, a shared proof-of-work (POW) system was proposed to secure new cryptocurrencies with different use cases.

Namecoin's flagship use case is the censorship-resistant top level domain .bit, which is functionally similar to .com or .net domains but is independent of ICANN, the main governing body for domain names.

🔗 Computing 🔗 Economics 🔗 Systems 🔗 Systems/Cybernetics 🔗 Chile

Project Cybersyn was a Chilean project from 1971–1973 during the presidency of Salvador Allende aimed at constructing a distributed decision support system to aid in the management of the national economy. The project consisted of four modules: an economic simulator, custom software to check factory performance, an operations room, and a national network of telex machines that were linked to one mainframe computer.

Project Cybersyn was based on viable system model theory approach to organizational design, and featured innovative technology for its time: it included a network of telex machines (Cybernet) in state-run enterprises that would transmit and receive information with the government in Santiago. Information from the field would be fed into statistical modeling software (Cyberstride) that would monitor production indicators, such as raw material supplies or high rates of worker absenteeism, in "almost" real time, alerting the workers in the first case and, in abnormal situations, if those parameters fell outside acceptable ranges by a very large degree, also the central government. The information would also be input into economic simulation software (CHECO, for CHilean ECOnomic simulator) that the government could use to forecast the possible outcome of economic decisions. Finally, a sophisticated operations room (Opsroom) would provide a space where managers could see relevant economic data, formulate feasible responses to emergencies, and transmit advice and directives to enterprises and factories in alarm situations by using the telex network.

The principal architect of the system was British operations research scientist Stafford Beer, and the system embodied his notions of organisational cybernetics in industrial management. One of its main objectives was to devolve decision-making power within industrial enterprises to their workforce in order to develop self-regulation of factories.

🔗 Aviation 🔗 Disaster management 🔗 Aviation/Aviation accident 🔗 Lists

This list of missing aircraft includes all of the aircraft that have disappeared in flight for reasons that have never been definitely determined. According to Annex 13 of the International Civil Aviation Organization, an aircraft is considered to be missing "when the official search has been terminated and the wreckage has not been located". However, there still remains a "grey area" on how much wreckage needs to be found for a plane to be declared "recovered". This list does not include every aviator, or air passenger that has ever gone missing as these are separate categories.

In the tables below, each missing aircraft is defined (in the Aircraft column) using one or more identifying features. If the aircraft was known by a custom or personalized name (e.g. Pathfinder), that name is presented first (in italics) followed by the aircraft type (in parentheses). The make of aircraft, although not necessarily a unique identifier, is also provided where appropriate. Aircraft registrations began to be used in the early 20th century for individual identification, so this is also included in the later tables (in parentheses).

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

Khaled El-Masri (also Khalid El-Masri and Khaled Masri, Levantine Arabic pronunciation: [ˈxaːlɪd elˈmɑsˤɾi, -ˈmɑsˤɾe], Arabic: خالد المصري‎) (born 29 June 1963) is a German and Lebanese citizen who was mistakenly abducted by the Macedonian police in 2003, and handed over to the U.S. Central Intelligence Agency (CIA). While in CIA custody, he was flown to Afghanistan, where he was held at a black site and routinely interrogated, beaten, strip-searched, sodomized, and subjected to other cruel forms of inhumane and degrading treatment and torture. After El-Masri held hunger strikes, and was detained for four months in the "Salt Pit", the CIA finally admitted his arrest and torture were a mistake and released him. He is believed to be among an estimated 3,000 detainees whom the CIA abducted from 2001–2005.

In May 2004, the U.S. Ambassador to Germany, Daniel R. Coats, convinced the German interior minister, Otto Schily, not to press charges or to reveal the program. El-Masri filed suit against the CIA for his arrest, extraordinary rendition and torture. In 2006, his suit El Masri v. Tenet, in which he was represented by the American Civil Liberties Union (ACLU), was dismissed by the United States District Court for the Eastern District of Virginia, based on the U.S. government's claiming the state secrets privilege. The ACLU said the Bush administration attempted to shield its abuses by invoking this privilege. The case was also dismissed by the Appeals Court for the Fourth Circuit, and in December 2007, the United States Supreme Court declined to hear the case.

On 13 December 2012, El-Masri won an Article 34 case at the European Court of Human Rights in Strasbourg. The court determined he had been tortured while held by CIA agents and ruled that Macedonia was responsible for abusing him while in the country, and knowingly transferring him to the CIA when torture was a possibility. It awarded him compensation. This marked the first time that CIA activities against detainees was legally declared as torture. The European Court condemned nations for collaborating with the United States in these secret programs.

🔗 Computing

In computing, the Two Generals' Problem is a thought experiment meant to illustrate the pitfalls and design challenges of attempting to coordinate an action by communicating over an unreliable link. In the experiment, two generals are only able to communicate with one another by sending a messenger through enemy territory. The experiment asks how they might reach an agreement on the time to launch an attack, while knowing that any messenger they send could be captured.

It is related to the more general Byzantine Generals Problem and appears often in introductory classes about computer networking (particularly with regard to the Transmission Control Protocol, where it shows that TCP can't guarantee state consistency between endpoints and why this is the case), though it applies to any type of two-party communication where failures of communication are possible. A key concept in epistemic logic, this problem highlights the importance of common knowledge. Some authors also refer to this as the Two Generals' Paradox, the Two Armies Problem, or the Coordinated Attack Problem. The Two Generals' Problem was the first computer communication problem to be proved to be unsolvable. An important consequence of this proof is that generalizations like the Byzantine Generals problem are also unsolvable in the face of arbitrary communication failures, thus providing a base of realistic expectations for any distributed consistency protocols.

🔗 Religion 🔗 Bible 🔗 Linguistics

In corpus linguistics, a hapax legomenon ( also or ; pl. hapax legomena; sometimes abbreviated to hapax) is a word that occurs only once within a context, either in the written record of an entire language, in the works of an author, or in a single text. The term is sometimes incorrectly used to describe a word that occurs in just one of an author's works, but more than once in that particular work. Hapax legomenon is a transliteration of Greek ἅπαξ λεγόμενον, meaning "(something) being said (only) once".

The related terms dis legomenon, tris legomenon, and tetrakis legomenon respectively (, , ) refer to double, triple, or quadruple occurrences, but are far less commonly used.

Hapax legomena are quite common, as predicted by Zipf's law, which states that the frequency of any word in a corpus is inversely proportional to its rank in the frequency table. For large corpora, about 40% to 60% of the words are hapax legomena, and another 10% to 15% are dis legomena. Thus, in the Brown Corpus of American English, about half of the 50,000 distinct words are hapax legomena within that corpus.

Hapax legomenon refers to a word's appearance in a body of text, not to either its origin or its prevalence in speech. It thus differs from a nonce word, which may never be recorded, may find currency and may be widely recorded, or may appear several times in the work which coins it, and so on.

🔗 Mathematics

A wallpaper group (or plane symmetry group or plane crystallographic group) is a mathematical classification of a two-dimensional repetitive pattern, based on the symmetries in the pattern. Such patterns occur frequently in architecture and decorative art, especially in textiles and tiles as well as wallpaper.

The simplest wallpaper group, Group p1, applies when there is no symmetry other than the fact that a pattern repeats over regular intervals in two dimensions, as shown in the section on p1 below.

Consider the following examples of patterns with more forms of symmetry:

Examples A and B have the same wallpaper group; it is called p4m in the IUC notation and *442 in the orbifold notation. Example C has a different wallpaper group, called p4g or 4*2 . The fact that A and B have the same wallpaper group means that they have the same symmetries, regardless of details of the designs, whereas C has a different set of symmetries despite any superficial similarities.

The number of symmetry groups depends on the number of dimensions in the patterns. Wallpaper groups apply to the two-dimensional case, intermediate in complexity between the simpler frieze groups and the three-dimensional space groups. Subtle differences may place similar patterns in different groups, while patterns that are very different in style, color, scale or orientation may belong to the same group.

A proof that there were only 17 distinct groups of such planar symmeries was first carried out by Evgraf Fedorov in 1891 and then derived independently by George Pólya in 1924. The proof that the list of wallpaper groups was complete only came after the much harder case of space groups had been done. The seventeen possible wallpaper groups are listed below in § The seventeen groups.

🔗 Cats 🔗 Ships 🔗 Rodents

The ship's cat has been a common feature on many trading, exploration, and naval ships dating to ancient times. Cats have been carried on ships for many reasons, most importantly to control rodents. Vermin aboard a ship can cause damage to ropes, woodwork, and more recently, electrical wiring. Also, rodents threaten ships' stores, devour crews' foodstuff, and could cause economic damage to ships' cargo such as grain. They are also a source of disease, which is dangerous for ships that are at sea for long periods of time. Rat fleas are carriers of plague, and rats on ships were believed to be a primary vector of the Black Death.

Cats naturally attack and kill rodents, and their natural ability to adapt to new surroundings made them suitable for service on a ship. In addition, they offer companionship and a sense of home, security and camaraderie to sailors away from home.

🔗 Mathematics 🔗 Statistics

The secretary problem is a problem that demonstrates a scenario involving optimal stopping theory. The problem has been studied extensively in the fields of applied probability, statistics, and decision theory. It is also known as the marriage problem, the sultan's dowry problem, the fussy suitor problem, the googol game, and the best choice problem.

The basic form of the problem is the following: imagine an administrator who wants to hire the best secretary out of ${\displaystyle n}$ rankable applicants for a position. The applicants are interviewed one by one in random order. A decision about each particular applicant is to be made immediately after the interview. Once rejected, an applicant cannot be recalled. During the interview, the administrator gains information sufficient to rank the applicant among all applicants interviewed so far, but is unaware of the quality of yet unseen applicants. The question is about the optimal strategy (stopping rule) to maximize the probability of selecting the best applicant. If the decision can be deferred to the end, this can be solved by the simple maximum selection algorithm of tracking the running maximum (and who achieved it), and selecting the overall maximum at the end. The difficulty is that the decision must be made immediately.

The shortest rigorous proof known so far is provided by the odds algorithm (Bruss 2000). It implies that the optimal win probability is always at least ${\displaystyle 1/e}$ (where e is the base of the natural logarithm), and that the latter holds even in a much greater generality (2003). The optimal stopping rule prescribes always rejecting the first ${\displaystyle \sim n/e}$ applicants that are interviewed and then stopping at the first applicant who is better than every applicant interviewed so far (or continuing to the last applicant if this never occurs). Sometimes this strategy is called the ${\displaystyle 1/e}$ stopping rule, because the probability of stopping at the best applicant with this strategy is about ${\displaystyle 1/e}$ already for moderate values of ${\displaystyle n}$. One reason why the secretary problem has received so much attention is that the optimal policy for the problem (the stopping rule) is simple and selects the single best candidate about 37% of the time, irrespective of whether there are 100 or 100 million applicants.