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🔗 Computing 🔗 Computing/Computer hardware

Rekursiv was a computer processor designed by David M. Harland in the mid-1980s for Linn Smart Computing in Glasgow, Scotland. It was one of the few computer architectures intended to implement object-oriented concepts directly in hardware, a form of high-level language computer architecture. The Rekursiv operated directly on objects rather than bits, nibbles, bytes and words. Virtual memory was used as a persistent object store and unusually, the processor instruction set supported recursion (hence the name).

The project originated in an initiative within the hi-fi manufacturer Linn Products to improve its manufacturing automation systems, which at the time ran on a DEC VAX minicomputer. This resulted in the design of Lingo, an object-oriented programming language derived from Smalltalk and ALGOL. Due to the poor performance of Lingo on the VAX, a subsidiary company, Linn Smart Computing Ltd., was formed to develop a new processor to efficiently run Lingo.

The Rekursiv processor consisted of four gate-array chips named Numerik (32-bit ALU), Logik (instruction sequencer), Objekt (object-oriented memory management unit) and Klock (processor clock and support logic). A small number of prototype VMEbus boards, called Hades, comprising these four chips plus 80 MB of RAM were produced. These were intended for installation in a host system such as a Sun-3 workstation.

Although the Rekursiv was never fully developed and was not a commercial success, several Hades boards were used in academic research projects in the UK. The last known copy of a Rekursiv computer ended up at the bottom of the Forth and Clyde canal in Glasgow.

🔗 Physiology 🔗 Evolutionary biology

In evolutionary biology and evolutionary psychology, the Trivers–Willard hypothesis, formally proposed by Robert Trivers and Dan Willard in 1973, suggests that female mammals are able to adjust offspring sex ratio in response to their maternal condition. For example, it may predict greater parental investment in males by parents in "good conditions" and greater investment in females by parents in "poor conditions" (relative to parents in good condition). The reasoning for this prediction is as follows: Assume that parents have information on the sex of their offspring and can influence their survival differentially. While pressures exist to maintain sex ratios at 50%, evolution will favor local deviations from this if one sex has a likely greater reproductive payoff than is usual.

Trivers and Willard also identified a circumstance in which reproducing individuals might experience deviations from expected offspring reproductive value—namely, varying maternal condition. In polygynous species males may mate with multiple females and low-condition males will achieve fewer or no matings. Parents in relatively good condition would then be under selection for mutations causing production and investment in sons (rather than daughters), because of the increased chance of mating experienced by these good-condition sons. Mating with multiple females conveys a large reproductive benefit, whereas daughters could translate their condition into only smaller benefits. An opposite prediction holds for poor-condition parents—selection will favor production and investment in daughters, so long as daughters are likely to be mated, while sons in poor condition are likely to be out-competed by other males and end up with zero mates (i.e., those sons will be a reproductive dead end).

The hypothesis was used to explain why, for example, Red Deer mothers would produce more sons when they are in good condition, and more daughters when in poor condition. In polyandrous species where some females mate with multiple males (and others get no matings) and males mate with one/few females (i.e., "sex-role reversed" species), these predictions from the Trivers–Willard hypothesis are reversed: parents in good condition will invest in daughters in order to have a daughter that can out-compete other females to attract multiple males, whereas parents in poor condition will avoid investing in daughters who are likely to get out-competed and will instead invest in sons in order to gain at least some grandchildren.

"Condition" can be assessed in multiple ways, including body size, parasite loads, or dominance, which has also been shown in macaques (Macaca sylvanus) to affect the sex of offspring, with dominant females giving birth to more sons and non-dominant females giving birth to more daughters. Consequently, high-ranking females give birth to a higher proportion of males than those who are low-ranking.

In their original paper, Trivers and Willard were not yet aware of the biochemical mechanism for the occurrence of biased sex ratios. Eventually, however, Melissa Larson et al. (2001) proposed that a high level of circulating glucose in the mother's bloodstream may favor the survival of male blastocysts. This conclusion is based on the observed male-skewed survival rates (to expanded blastocyst stages) when bovine blastocysts were exposed to heightened levels of glucose. As blood glucose levels are highly correlated with access to high-quality food, blood glucose level may serve as a proxy for "maternal condition". Thus, heightened glucose functions as one possible biochemical mechanism for observed Trivers–Willard effects.

Wild and West published a paper describing a mathematical model built on the Trivers–Willard hypothesis that allows precise predictions of alterations in sex-ratio under different circumstances.

🔗 Philosophy 🔗 Education 🔗 Philosophy/Analytic philosophy

In philosophy, Wittgenstein's ladder is a metaphor set out by Ludwig Wittgenstein about learning. In what may be a deliberate reference to Søren Kierkegaard's Concluding Unscientific Postscript to Philosophical Fragments, the penultimate proposition of the Tractatus Logico-Philosophicus (translated from the original German) reads:

6.54

   My propositions serve as elucidations in the following way: anyone who understands me eventually recognizes them as nonsensical, when he has used them—as steps—to climb beyond them. (He must, so to speak, throw away the ladder after he has climbed up it.)

   He must transcend these propositions, and then he will see the world aright.

Given the preceding problematic at work in his Tractatus, this passage suggests that, if a reader understands Wittgenstein's aims in the text, then those propositions the reader would have just read would be recognized as nonsense. From Propositions 6.4–6.54, the Tractatus shifts its focus from primarily logical considerations to what may be considered more traditionally philosophical topics (God, ethics, meta-ethics, death, the will) and, less traditionally along with these, the mystical. The philosophy presented in the Tractatus attempts to demonstrate just what the limits of language are—and what it is to run up against them. Among what can be said for Wittgenstein are the propositions of natural science, and to the nonsensical, or unsayable, those subjects associated with philosophy traditionally—ethics and metaphysics, for instance.

Curiously, the penultimate proposition of the Tractatus, proposition 6.54, states that once one understands the propositions of the Tractatus, one will recognize that they are nonsensical (unsinnig), and that they must be thrown away. Proposition 6.54, then, presents a difficult interpretative problem. If the so-called picture theory of language is correct, and it is impossible to represent logical form, then the theory, by trying to say something about how language and the world must be for there to be meaning, is self-undermining. This is to say that the picture theory of language itself requires that something be said about the logical form sentences must share with reality for meaning to be possible. This requires doing precisely what the picture theory of language precludes. It would appear, then, that the metaphysics and the philosophy of language endorsed by the Tractatus give rise to a paradox: for the Tractatus to be true, it will necessarily have to be nonsense by self-application; but for this self-application to render the propositions of the Tractatus nonsense (in the Tractarian sense), then the Tractatus must be true.

Other philosophers before Wittgenstein, including Zhuang Zhou, Schopenhauer and Fritz Mauthner, had used a similar metaphor.

In his notes of 1930 Wittgenstein returns to the image of a ladder with a different perspective:

I might say: if the place I want to get could only be reached by way of a ladder, I would give up trying to get there. For the place I really have to get to is a place I must already be at now.
Anything that I might reach by climbing a ladder does not interest me.

🔗 Crime 🔗 Organized crime 🔗 Belgium

The Brabant killers, also named the Nijvel Gang in Dutch-speaking media (Dutch: De Bende van Nijvel), and the mad killers of Brabant in French-speaking media (French: Les Tueurs fous du Brabant), are believed to be responsible for a series of violent attacks that mainly occurred in the Belgian province of Brabant between 1982 and 1985. A total of 28 people died and 22 were injured. The actions of the gang, believed to consist of a core of three men, made it Belgium's most notorious unsolved crime spree. The active participants were known as The Giant (a tall man who may have been the leader); the Killer (the main shooter) and the Old Man (a middle aged man who drove). The identities and whereabouts of the "Brabant killers" are unknown. Although significant resources are still dedicated to it, the most recent arrests in the case were of the now-retired original senior detectives. Failure to catch the gang resulted in a parliamentary inquiry. There have been many theories of ulterior motives behind the crimes.

🔗 Biography 🔗 Espionage 🔗 Germany 🔗 Military history 🔗 Military history/Military biography 🔗 Biography/military biography 🔗 United Kingdom 🔗 Military history/World War II

Eric Arthur Roberts (18 June 1907 – 17 or 18 December 1972) was an MI5 agent during the Second World War under the alias Jack King. By posing as a Gestapo agent and infiltrating fascist groups in the UK, Roberts was able to prevent secret information finding its way to Germany. Roberts continued to work for the security services after the war, particularly in Vienna, but it was a time of great anxiety in the services because of the suspicions surrounding double agents such as the Cambridge spy ring.

Roberts never felt completely accepted by MI5 because of his social background and a desk role did not suit him as well as his wartime role had. He is the subject of the biography Agent Jack (2018) by Robert Hutton, and his adventures were the inspiration for the novel Our Friends In Berlin by Anthony Quinn and for a major character in the novel Transcription by Kate Atkinson.

🔗 Physics 🔗 Weather 🔗 Weather/Weather

A light pillar is an atmospheric optical phenomenon in which a vertical beam of light appears to extend above and/or below a light source. The effect is created by the reflection of light from tiny ice crystals that are suspended in the atmosphere or that comprise high-altitude clouds (e.g. cirrostratus or cirrus clouds). If the light comes from the Sun (usually when it is near or even below the horizon), the phenomenon is called a sun pillar or solar pillar. Light pillars can also be caused by the Moon or terrestrial sources, such as streetlights and erupting volcanoes.

🔗 Maps

In cartography, a trap street is a fictitious entry in the form of a misrepresented street on a map, often outside the area the map nominally covers, for the purpose of "trapping" potential copyright violators of the map who, if caught, would be unable to explain the inclusion of the "trap street" on their map as innocent. On maps that are not of streets, other "copyright trap" features (such as nonexistent towns, or mountains with the wrong elevations) may be inserted or altered for the same purpose.

Trap streets are often nonexistent streets; but sometimes, rather than actually depicting a street where none exists, a map will misrepresent the nature of a street in a fashion that can still be used to detect copyright violators but is less likely to interfere with navigation. For instance, a map might add nonexistent bends to a street, or depict a major street as a narrow lane, without changing its location or its connections to other streets.

Trap streets are rarely acknowledged by publishers. One known case is a popular driver's atlas for the city of Athens, Greece, which has a warning inside its front cover that potential copyright violators should beware of trap streets.

🔗 Aviation 🔗 Telecommunications 🔗 Guild of Copy Editors

In the U.S., Federal Communications Commission (FCC) regulations prohibit the use of mobile phones aboard aircraft in flight. Contrary to popular misconception, the Federal Aviation Administration (FAA) does not actually prohibit the use of personal electronic devices (including cell phones) on aircraft. Paragraph (b)(5) of 14 CFR 91.21 leaves it up to the airlines to determine if devices can be used in flight, allowing use of "Any other portable electronic device that the operator of the aircraft has determined will not cause interference with the navigation or communication system of the aircraft on which it is to be used."

In Europe, regulations and technology have allowed the limited introduction of the use of passenger mobile phones on some commercial flights, and elsewhere in the world many airlines are moving towards allowing mobile phone use in flight. Many airlines still do not allow the use of mobile phones on aircraft. Those that do often ban the use of mobile phones during take-off and landing.

Many passengers are pressing airlines and their governments to allow and deregulate mobile phone use, while some airlines, under the pressure of competition, are also pushing for deregulation or seeking new technology which could solve the present problems. On the other hand, official aviation agencies and safety boards are resisting any relaxation of the present safety rules unless and until it can be conclusively shown that it would be safe to do so. There are both technical and social factors which make the issues more complex than a simple discussion of safety versus hazard.

🔗 Mathematics

A squircle is a shape intermediate between a square and a circle. There are at least two definitions of "squircle" in use, the most common of which is based on the superellipse. The word "squircle" is a portmanteau of the words "square" and "circle". Squircles have been applied in design and optics.

🔗 Lists 🔗 Songs

This is a list of musical compositions or pieces of music that have unusual time signatures. "Unusual" is here defined to be any time signature other than simple time signatures with top numerals of 2, 3, or 4 and bottom numerals of 2, 4, or 8, and compound time signatures with top numerals of 6, 9, or 12 and bottom numerals 4, 8, or 16.

The conventions of musical notation typically allow for more than one written representation of a particular piece. The chosen time signature largely depends upon musical context, personal taste of the composer or transcriber, and the graphic layout on the written page. Frequently, published editions were written in a specific time signature to visually signify the tempo for slow movements in symphonies, sonatas, and concerti.

A perfectly consistent unusual metrical pattern may be notated in a more familiar time signature that does not correspond to it. For example, the Passacaglia from Britten's opera Peter Grimes consists of variations over a recurring bass line eleven beats in length but is notated in ordinary ⁴
₄ time, with each variation lasting 2+3⁄4 bars, and therefore commencing each time one crotchet earlier in the bar than the preceding one.