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πŸ”— Lithops

πŸ”— Plants

Lithops is a genus of succulent plants in the ice plant family, Aizoaceae. Members of the genus are native to southern Africa. The name is derived from the Ancient Greek words λίθος (lΓ­thos), meaning "stone," and α½„Οˆ (Γ³ps), meaning "face," referring to the stone-like appearance of the plants. They avoid being eaten by blending in with surrounding rocks and are often known as pebble plants or living stones. The formation of the name from the Ancient Greek "-ops" means that even a single plant is called a Lithops.

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πŸ”— Fabrice Bellard

πŸ”— Biography πŸ”— Computing πŸ”— France πŸ”— Computing/Software

Fabrice Bellard (French pronunciation: ​[fa.bʁis bΙ›.laʁ]) is a computer programmer who created the FFmpeg and QEMU software projects. He has also developed a number of other programs, including the Tiny C Compiler.

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πŸ”— Telling the Bees

πŸ”— Agriculture πŸ”— England πŸ”— Folklore

Telling the bees is a traditional custom of many European countries in which bees would be told of important events in their keeper's lives, such as births, marriages, or departures and returns in the household. If the custom was omitted or forgotten and the bees were not "put into mourning" then it was believed a penalty would be paid, such as the bees leaving their hive, stopping the production of honey, or dying. The custom is best known in England, but has also been recorded in Ireland, Wales, Germany, Netherlands, France, Switzerland, Bohemia, and the United States.

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πŸ”— Werckmeister Temperment

Werckmeister temperaments are the tuning systems described by Andreas Werckmeister in his writings. The tuning systems are numbered in two different ways: the first refers to the order in which they were presented as "good temperaments" in Werckmeister's 1691 treatise, the second to their labelling on his monochord. The monochord labels start from III since just intonation is labelled I and quarter-comma meantone is labelled II. The temperament commonly known as "Werckmeister III" is referred to in this article as "Werckmeister I (III)".

The tunings I (III), II (IV) and III (V) were presented graphically by a cycle of fifths and a list of major thirds, giving the temperament of each in fractions of a comma. Werckmeister used the organbuilder's notation of ^ for a downwards tempered or narrowed interval and v for an upward tempered or widened one. (This appears counterintuitive - it is based on the use of a conical tuning tool which would reshape the ends of the pipes.) A pure fifth is simply a dash. Werckmeister was not explicit about whether the syntonic comma or Pythagorean comma was meant: the difference between them, the so-called schisma, is almost inaudible and he stated that it could be divided up among the fifths.

The last "Septenarius" tuning was not conceived in terms of fractions of a comma, despite some modern authors' attempts to approximate it by some such method. Instead, Werckmeister gave the string lengths on the monochord directly, and from that calculated how each fifth ought to be tempered.

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πŸ”— Haversine Formula

πŸ”— Mathematics πŸ”— Geography

The haversine formula determines the great-circle distance between two points on a sphere given their longitudes and latitudes. Important in navigation, it is a special case of a more general formula in spherical trigonometry, the law of haversines, that relates the sides and angles of spherical triangles.

The first table of haversines in English was published by James Andrew in 1805, but Florian Cajori credits an earlier use by JosΓ© de Mendoza y RΓ­os in 1801. The term haversine was coined in 1835 by James Inman.

These names follow from the fact that they are customarily written in terms of the haversine function, given by hav(ΞΈ) = sin2(ΞΈ/2). The formulas could equally be written in terms of any multiple of the haversine, such as the older versine function (twice the haversine). Prior to the advent of computers, the elimination of division and multiplication by factors of two proved convenient enough that tables of haversine values and logarithms were included in nineteenth and early twentieth century navigation and trigonometric texts. These days, the haversine form is also convenient in that it has no coefficient in front of the sin2 function.

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πŸ”— Endling

πŸ”— Extinction

An endling is the last known individual of a species or subspecies. Once the endling dies, the species becomes extinct. The word was coined in correspondence in the scientific journal Nature. Alternative names put forth for the last individual of its kind include ender and terminarch.

The word relict may also be used, but usually refers to a population, rather than an individual, that is the last of a species.

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πŸ”— Toba catastrophe theory

πŸ”— Volcanoes πŸ”— Disaster management πŸ”— Geology πŸ”— Indonesia

The Toba supereruption was a supervolcanic eruption that occurred about 75,000 years ago at the site of present-day Lake Toba in Sumatra, Indonesia. It is one of the Earth's largest known eruptions. The Toba catastrophe theory holds that this event caused a global volcanic winter of six to ten years and possibly a 1,000-year-long cooling episode.

In 1993, science journalist Ann Gibbons posited that a population bottleneck occurred in human evolution about 70,000 years ago, and she suggested that this was caused by the eruption. Geologist Michael R. Rampino of New York University and volcanologist Stephen Self of the University of Hawaii at Manoa support her suggestion. In 1998, the bottleneck theory was further developed by anthropologist Stanley H. Ambrose of the University of Illinois at Urbana–Champaign. Both the link and global winter theories are controversial. The Toba event is the most closely studied supereruption.

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πŸ”— Erotetics

πŸ”— Philosophy πŸ”— Philosophy/Logic

Erotetics or erotetic logic is a part of logic, devoted to logical analysis of questions. It is sometimes called the logic of questions and answers.

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πŸ”— YInMn Blue

πŸ”— Color

YInMn Blue (for yttrium, indium, manganese), also known as Oregon Blue, Mas Blue, or Yin Min Blue, is an inorganic blue pigment that was discovered accidentally by Professor Mas Subramanian and his then-graduate student Andrew E. Smith at Oregon State University in 2009. It is the first inorganic blue pigment discovered in 200 years, since cobalt blue was identified in 1802.

The compound has a unique trigonal bipyramidal structure, and further research has discovered it may be modified to create green, purple, and orange pigments.

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πŸ”— Pattern theory

πŸ”— Mathematics

Pattern theory, formulated by Ulf Grenander, is a mathematical formalism to describe knowledge of the world as patterns. It differs from other approaches to artificial intelligence in that it does not begin by prescribing algorithms and machinery to recognize and classify patterns; rather, it prescribes a vocabulary to articulate and recast the pattern concepts in precise language. Broad in its mathematical coverage, Pattern Theory spans algebra and statistics, as well as local topological and global entropic properties.

In addition to the new algebraic vocabulary, its statistical approach is novel in its aim to:

  • Identify the hidden variables of a data set using real world data rather than artificial stimuli, which was previously commonplace.
  • Formulate prior distributions for hidden variables and models for the observed variables that form the vertices of a Gibbs-like graph.
  • Study the randomness and variability of these graphs.
  • Create the basic classes of stochastic models applied by listing the deformations of the patterns.
  • Synthesize (sample) from the models, not just analyze signals with them.

The Brown University Pattern Theory Group was formed in 1972 by Ulf Grenander. Many mathematicians are currently working in this group, noteworthy among them being the Fields Medalist David Mumford. Mumford regards Grenander as his "guru" in Pattern Theory.