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🔗 Mathematics 🔗 Statistics

In probability theory, the birthday problem or birthday paradox concerns the probability that, in a set of n randomly chosen people, some pair of them will have the same birthday. By the pigeonhole principle, the probability reaches 100% when the number of people reaches 367 (since there are only 366 possible birthdays, including February 29). However, 99.9% probability is reached with just 70 people, and 50% probability with 23 people. These conclusions are based on the assumption that each day of the year (excluding February 29) is equally probable for a birthday.

Actual birth records show that different numbers of people are born on different days. In this case, it can be shown that the number of people required to reach the 50% threshold is 23 or fewer. For example, if half the people were born on one day and the other half on another day, then any two people would have a 50% chance of sharing a birthday.

It may well seem surprising that a group of just 23 individuals is required to reach a probability of 50% that at least two individuals in the group have the same birthday: this result is perhaps made more plausible by considering that the comparisons of birthday will actually be made between every possible pair of individuals = 23 × 22/2 = 253 comparisons, which is well over half the number of days in a year (183 at most), as opposed to fixing on one individual and comparing his or her birthday to everyone else's. The birthday problem is not a "paradox" in the literal logical sense of being self-contradictory, but is merely unintuitive at first glance.

Real-world applications for the birthday problem include a cryptographic attack called the birthday attack, which uses this probabilistic model to reduce the complexity of finding a collision for a hash function, as well as calculating the approximate risk of a hash collision existing within the hashes of a given size of population.

The history of the problem is obscure. W. W. Rouse Ball indicated (without citation) that it was first discussed by Harold Davenport. However, Richard von Mises proposed an earlier version of what is considered today to be the birthday problem.

🔗 Birds 🔗 Animal rights 🔗 Veterinary medicine

Abnormal behavior of birds in captivity has been found to occur among both domesticated and wild birds. Abnormal behavior can be defined in several ways. Statistically, 'abnormal' is when the occurrence, frequency or intensity of a behaviour varies statistically significantly, either more or less, from the normal value. This means that theoretically, almost any behaviour could become 'abnormal' in an individual. Less formally, 'abnormal' includes any activity judged to be outside the normal behaviour pattern for captive birds of that particular class or age. For example, running rather than flying may be a normal behaviour and regularly observed in one species, however, in another species it might be normal but becomes 'abnormal' if it reaches a high frequency, or in another species it is rarely observed and any incidence is considered 'abnormal'. This article does not include 'one-off' behaviours performed by individual birds that might be considered abnormal for that individual, unless these are performed repeatedly by other individuals in the species and are recognised as part of the ethogram of that species.

Most abnormal behaviours can be categorised collectively (e.g., eliminative, ingestive, stereotypies), however, many abnormal behaviours fall debatably into several of these categories and categorisation is therefore not attempted in this article. Abnormal behaviours here are considered to be related to captive housing but may also be due to medical conditions. The article does not include behaviours in birds that are genetically modified to express abnormal behaviour.

🔗 Computing 🔗 Computer science 🔗 Cognitive science 🔗 Software 🔗 Software/Computing 🔗 Databases 🔗 Databases/Computer science

Cyc (pronounced SYKE, ) is a long-living artificial intelligence project that aims to assemble a comprehensive ontology and knowledge base that spans the basic concepts and rules about how the world works. Hoping to capture common sense knowledge, Cyc focuses on implicit knowledge that other AI platforms may take for granted. This is contrasted with facts one might find somewhere on the internet or retrieve via a search engine or Wikipedia. Cyc enables AI applications to perform human-like reasoning and be less "brittle" when confronted with novel situations.

Douglas Lenat began the project in July 1984 at MCC, where he was Principal Scientist 1984–1994, and then, since January 1995, has been under active development by the Cycorp company, where he is the CEO.

🔗 Architecture

A saw-tooth roof is a roof comprising a series of ridges with dual pitches either side. The steeper surfaces are glazed to admit daylight and face away from the equator to shield workers and machinery from direct sunlight. This kind of roof admits natural light into a deep plan building or factory. It was therefore most commonly built during the Machine Age from the mid-nineteenth century to the mid-twentieth, when electrification of factories was not yet common.

Many factories of the era had little or no electrical wiring; their main power sources for the machinery were often steam engines driving line shafting, and the lighting was chiefly via daylighting through the windows. Work done at night, when necessary, was typically lit by oil lamps and candles, but many factories closed for the night. Their norm of an early working day (for example, 6 a.m. to 4 p.m.) was not merely a tradition but a functional decision based on this reliance on daylighting. The same was true of the farmer's workday, for the same reason.

🔗 Skepticism 🔗 Primates

The hundredth monkey effect is a hypothetical phenomenon in which a new behaviour or idea is said to spread rapidly by unexplained means from one group to all related groups once a critical number of members of one group exhibit the new behaviour or acknowledge the new idea.

One of the primary factors in the promulgation of the story is that many authors quote secondary, tertiary or post-tertiary sources which have themselves misrepresented the original observations.

🔗 Climate change 🔗 Environment 🔗 Plants 🔗 Arctic 🔗 Palaeontology 🔗 Geology

The Azolla event is a scenario hypothesized to have occurred in the middle Eocene epoch, around 49 million years ago, when blooms of the freshwater fern Azolla are thought to have happened in the Arctic Ocean. As they sank to the stagnant sea floor, they were incorporated into the sediment; the resulting draw-down of carbon dioxide has been speculated to have helped transform the planet from a "greenhouse Earth" state, hot enough for turtles and palm trees to prosper at the poles, to the current icehouse Earth known as the Late Cenozoic Ice Age.

🔗 Crime 🔗 Law 🔗 England 🔗 Middle Ages 🔗 Middle Ages/History 🔗 Law Enforcement 🔗 Sociology 🔗 University of Oxford 🔗 British crime

The St Scholastica Day riot took place in Oxford, England, on 10 February 1355, Saint Scholastica's Day. The disturbance began when two students from the University of Oxford complained about the quality of wine served to them in the Swindlestock Tavern, which stood on Carfax, in the centre of the town. The students quarrelled with the taverner; the argument quickly escalated to blows. The inn's customers joined in on both sides, and the resulting melee turned into a riot. The violence started by the bar brawl continued over three days, with armed gangs coming in from the countryside to assist the townspeople. University halls and students' accommodation were raided and the inhabitants murdered; there were some reports of clerics being scalped. Around 30 townsfolk were killed, as were up to 63 members of the university.

Violent disagreements between townspeople and students had arisen several times previously, and 12 of the 29 coroners' courts held in Oxford between 1297 and 1322 concerned murders by students. The University of Cambridge was established in 1209 by scholars who left Oxford following the lynching of two students by the town's citizens.

King Edward III sent judges to the town with commissions of oyer and terminer to determine what had gone on and to advise what steps should be taken. He came down on the side of the university authorities, who were given additional powers and responsibilities to the disadvantage of the town's authorities. The town was fined 500 marks and its mayor and bailiffs were sent to the Marshalsea prison in London. John Gynwell, the Bishop of Lincoln, imposed an interdict on the town for one year, which banned all religious practices, including services (except on key feast days), burials and marriages; only baptisms of young children were allowed.

An annual penance was imposed on the town: each year, on St Scholastica's Day, the mayor, bailiffs and sixty townspeople were to attend a Mass at the University Church of St Mary the Virgin for those killed; the town was also made to pay the university a fine of one penny for each scholar killed. The practice was dropped in 1825; in 1955—the 600th anniversary of the riots—in an act of conciliation the mayor was given an honorary degree and the vice-chancellor was made an honorary freeman of the city.

🔗 United States 🔗 Biography 🔗 Medicine 🔗 Biology 🔗 Biography/science and academia 🔗 India 🔗 Molecular and Cell Biology 🔗 Medicine/Medical genetics 🔗 United States/Asian Americans

Har Gobind Khorana (9 January 1922 – 9 November 2011) was an Indian-American biochemist. While on the faculty of the University of Wisconsin–Madison, he shared the 1968 Nobel Prize for Physiology or Medicine with Marshall W. Nirenberg and Robert W. Holley for research that showed the order of nucleotides in nucleic acids, which carry the genetic code of the cell and control the cell's synthesis of proteins. Khorana and Nirenberg were also awarded the Louisa Gross Horwitz Prize from Columbia University in the same year.

Born in British India, Khorana served on the faculties of three universities in North America. He became a naturalized citizen of the United States in 1966, and received the National Medal of Science in 1987.

🔗 Marketing & Advertising

Ad creep is the "creep" of advertising into previously ad-free spaces.

The earliest verified appearance of the term "ad creep" is in a 1996 article "Creeping Commercials: Ads Worming Way Into TV Scripts" by Steve Johnson for the Chicago Tribune, however it may have been coined by a subscriber to Stay Free! magazine, according to another source.

While the virtues of advertising can be debated, ad-creep often especially refers to advertising which is invasive and coercive, such as ads in schools, doctor's offices and hospitals, restrooms, elevators, on ATMs, on garbage cans, on vehicles, on restaurant menus, and countless other items. In Steve Johnson's piece referenced above, he criticizes product placement and "creative advertising enhancements" as "one more manifestation of an environment in which the commercial assault is almost nonstop". Commercial Alert, a nonprofit organization founded by Public Citizen "to keep the commercial culture within its proper sphere, and to prevent it from exploiting children and subverting the higher values of family, community, environmental integrity and democracy" also characterizes "ad creep" as an assault, with ad companies fighting a "relentless battle to claim every waking moment, and what one executive called, with chilling candor, mind share". A 2017 Daily Express story in the UK suggests "the creeping incursion of adverts in Windows 10" has been an issue.

On the other hand, modern advertisers are compelled to react to changes in consumer habits. An article in The New York Times notes that "consumers’ viewing and reading habits are so scattershot now that many advertisers say the best way to reach time-pressed consumers is to try to catch their eye at literally every turn." And, the article suggests that ad agencies believe that as long as ads are entertaining, people may not mind the saturation. As people have turned from traditional media, advertisers have not only struggled to create brand awareness, but there is also a move to "microtarget people at precisely timed moments" as well, according to an article in Stay Free!.

Occasionally, the term "Ad Creep" has been used to describe a process of slowly infusing more ads into places where ads have been expected (television shows, for example) such as in a 2011 Advertising Age article describing the increase in both the time devoted to ads and the number of ad messages in the Super Bowl. This is not a standard use of the term, but it is related. A 2017 blog post by the chief global analyst of Kantar Millward Brown, a marketing firm, notes "that average ad loads on national television in the U.S. continued to creep upwards from 10.4 minutes per hour in December 2014, to 10.9 minutes in December 2016". Although the increase is less than 5%, he suggests "marketers should be concerned because the evidence suggests that more clutter is a bad thing for brands."

🔗 Sports

Naismith's rule helps with the planning of a walking or hiking expedition by calculating how long it will take to travel the intended route, including any extra time taken when walking uphill. This rule of thumb was devised by William W. Naismith, a Scottish mountaineer, in 1892. A modern version can be formulated as follows:

Allow one hour for every 3 miles (5 km) forward, plus an additional hour for every 2,000 feet (600 m) of ascent.