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🔗 Psychology

The behavioral immune system is a phrase coined by the psychological scientist Mark Schaller to refer to a suite of psychological mechanisms that allow individual organisms to detect the potential presence of disease-causing parasites in their immediate environment, and to engage in behaviors that prevent contact with those objects and individuals.

These mechanisms include sensory processes through which cues connoting the presence of parasitic infections are perceived (e.g., the smell of a foul odor, the sight of pox or pustules), as well as stimulus–response systems through which these sensory cues trigger a cascade of aversive affective, cognitive, and behavioral reactions (e.g., arousal of disgust, automatic activation of cognitions that connote the threat of disease, behavioral avoidance).

The existence of a behavioral immune system has been documented across many animal species, including humans. It is theorized that the mechanisms that comprise the behavioral immune system evolved as a crude first line of defense against disease-causing pathogens.

An animated image showing the definition of pi. A number line is marked off by a circle of unit diameter. Starting from zero, the circle "unrolls" its circumference. At one full turn, the unrolled circumference has extended to the point we call π. This number is real but irrational, transcendental, and cannot be constructed with compass and straightedge.

Animation credit: John Reid
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🔗 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.

🔗 Biography 🔗 Internet culture 🔗 Mathematics 🔗 Biography/science and academia

Cleo was the pseudonym of an anonymous mathematician active on the mathematics Stack Exchange from 2013 to 2015, who became known for providing precise answers to complex mathematical integration problems without showing any intermediate steps. Due to the extraordinary accuracy and speed of the provided solutions, mathematicians debated whether Cleo was an individual genius, a collective pseudonym, or even an early artificial intelligence system.

During the poster's active period, Cleo posted 39 answers to advanced mathematical questions, primarily focusing on complex integration problems that had stumped other users. Cleo's answers were characterized by being consistently correct while providing no explanation of methodology, often appearing within hours of the original posts. The account claimed to be limited in interaction due to an unspecified medical condition.

The mystery surrounding Cleo's identity and mathematical abilities generated significant interest in the mathematical community, with users attempting to analyze solution patterns and writing style for clues. Some compared Cleo to historical mathematical figures like Srinivasa Ramanujan, known for providing solutions without conventional proofs. In 2025, Cleo was revealed to be Vladimir Reshetnikov, a software developer originally from Uzbekistan.

🔗 Computing 🔗 China 🔗 East Asia 🔗 Writing systems 🔗 Hong Kong

Han unification is an effort by the authors of Unicode and the Universal Character Set to map multiple character sets of the so-called CJK languages into a single set of unified characters. Han characters are a common feature of written Chinese (hanzi), Japanese (kanji), and Korean (hanja).

Modern Chinese, Japanese and Korean typefaces typically use regional or historical variants of a given Han character. In the formulation of Unicode, an attempt was made to unify these variants by considering them different glyphs representing the same "grapheme", or orthographic unit, hence, "Han unification", with the resulting character repertoire sometimes contracted to Unihan.

Unihan can also refer to the Unihan Database maintained by the Unicode Consortium, which provides information about all of the unified Han characters encoded in the Unicode Standard, including mappings to various national and industry standards, indices into standard dictionaries, encoded variants, pronunciations in various languages, and an English definition. The database is available to the public as text files and via an interactive website. The latter also includes representative glyphs and definitions for compound words drawn from the free Japanese EDICT and Chinese CEDICT dictionary projects (which are provided for convenience and are not a formal part of the Unicode Standard).

🔗 Astronomy 🔗 Astronomy/Astronomical objects 🔗 Astronomy/Solar System

319 Leona (provisional designation A920 HE), is a dark asteroid and tumbling slow rotator from the outermost regions of the asteroid belt, approximately 70 kilometers in diameter. It was discovered on 8 October 1891, by French astronomer Auguste Charlois at Nice Observatory in southwestern France. Any reference of its name to a person is unknown. On 12 December 2023 Leona will occult Betelgeuse as seen from southern Europe.

🔗 United States/U.S. Government 🔗 United States 🔗 International relations 🔗 Law 🔗 Law Enforcement 🔗 United States Public Policy 🔗 Pirate Politics 🔗 International relations/International law 🔗 United States/U.S. Public Policy 🔗 Trade

The Anti-Counterfeiting Trade Agreement (ACTA) was a proposed multilateral treaty for the purpose of establishing international standards for intellectual property rights enforcement. The agreement aims to establish an international legal framework for targeting counterfeit goods, generic medicines and copyright infringement on the Internet, and would create a new governing body outside existing forums, such as the World Trade Organization, the World Intellectual Property Organization, and the United Nations.

The agreement was signed in October 2011 by Australia, Canada, Japan, Morocco, New Zealand, Singapore, South Korea, and the United States. In 2012, Mexico, the European Union and 22 countries that are member states of the European Union signed as well. One signatory (Japan) has ratified (formally approved) the agreement, which would come into force in countries that ratified it after ratification by six countries.

Industrial groups with interests in copyright, trademarks and other types of intellectual property said that ACTA was a response to "the increase in global trade of counterfeit goods and pirated copyright protected works". Organizations such as the Motion Picture Association of America and International Trademark Association are understood to have had a significant influence over the ACTA agenda.

Organisations representing citizens and non-governmental interests argued that ACTA could infringe fundamental rights including freedom of expression and privacy. ACTA has also been criticised by Doctors Without Borders for endangering access to medicines in developing countries. The nature of negotiations was criticized as secretive and has excluded non-governmental organization, developing countries and the general public from the agreement's negotiation process and it has been described as policy laundering by critics including the Electronic Frontier Foundation and the Entertainment Consumers Association.

The signature of the EU and many of its member states resulted in widespread protests across Europe. European Parliament rapporteur Kader Arif resigned. His replacement, British MEP David Martin, recommended that the Parliament should reject ACTA, stating: "The intended benefits of this international agreement are far outweighed by the potential threats to civil liberties". On 4 July 2012, the European Parliament declined its consent, effectively rejecting it, 478 votes to 39, with 165 abstentions.

🔗 Mathematics 🔗 Physics 🔗 Statistics

In mathematical statistics, the Kullback–Leibler divergence (also called relative entropy and I-divergence), denoted ${\displaystyle D_{\text{KL}}(P\parallel Q)}$, is a type of statistical distance: a measure of how one probability distribution P is different from a second, reference probability distribution Q. A simple interpretation of the KL divergence of P from Q is the expected excess surprise from using Q as a model when the actual distribution is P. While it is a distance, it is not a metric, the most familiar type of distance: it is not symmetric in the two distributions (in contrast to variation of information), and does not satisfy the triangle inequality. Instead, in terms of information geometry, it is a type of divergence, a generalization of squared distance, and for certain classes of distributions (notably an exponential family), it satisfies a generalized Pythagorean theorem (which applies to squared distances).

In the simple case, a relative entropy of 0 indicates that the two distributions in question have identical quantities of information. Relative entropy is a nonnegative function of two distributions or measures. It has diverse applications, both theoretical, such as characterizing the relative (Shannon) entropy in information systems, randomness in continuous time-series, and information gain when comparing statistical models of inference; and practical, such as applied statistics, fluid mechanics, neuroscience and bioinformatics.

🔗 Music theory 🔗 Classical music 🔗 Music/Music genres

Aleatoric music (also aleatory music or chance music; from the Latin word alea, meaning "dice") is music in which some element of the composition is left to chance, and/or some primary element of a composed work's realization is left to the determination of its performer(s). The term is most often associated with procedures in which the chance element involves a relatively limited number of possibilities.

The term became known to European composers through lectures by acoustician Werner Meyer-Eppler at the Darmstadt International Summer Courses for New Music in the beginning of the 1950s. According to his definition, "a process is said to be aleatoric ... if its course is determined in general but depends on chance in detail". Through a confusion of Meyer-Eppler's German terms Aleatorik (noun) and aleatorisch (adjective), his translator created a new English word, "aleatoric" (rather than using the existing English adjective "aleatory"), which quickly became fashionable and has persisted. More recently, the variant "aleatoriality" has been introduced.

🔗 Spaceflight 🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Military history/Military science, technology, and theory 🔗 Moon 🔗 Military history/Cold War 🔗 Cold War 🔗 Solar System 🔗 Solar System/Moon

Project A119, also known as A Study of Lunar Research Flights, was a top-secret plan developed in 1958 by the United States Air Force. The aim of the project was to detonate a nuclear bomb on the Moon, which would help in answering some of the mysteries in planetary astronomy and astrogeology. If the explosive device detonated on the surface, not in a lunar crater, the flash of explosive light would have been faintly visible to people on Earth with their naked eye, a show of force resulting in a possible boosting of domestic morale in the capabilities of the United States, a boost that was needed after the Soviet Union took an early lead in the Space Race and was also working on a similar project.

The project was never carried out, being cancelled primarily out of a fear of a negative public reaction, with the potential militarization of space that it would also have signified, and because a Moon landing would undoubtedly be a more popular achievement in the eyes of the American and international public alike. A similar project by the Soviet Union also never came to fruition.

The existence of the US project was revealed in 2000 by a former executive at the National Aeronautics and Space Administration (NASA), Leonard Reiffel, who led the project in 1958. A young Carl Sagan was part of the team responsible for predicting the effects of a nuclear explosion in vacuum and low gravity and in evaluating the scientific value of the project. The project documents remained secret for nearly 45 years, and despite Reiffel's revelations, the United States government has never officially recognized its involvement in the study.