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๐ Al-Jazari
Badฤซสฟ az-Zaman Abu l-สฟIzz ibn Ismฤสฟฤซl ibn ar-Razฤz al-Jazarฤซ (1136โ1206, Arabic: ุจุฏูุน ุงูุฒู ุงู ุฃูุจู ุงูููุนูุฒู ุฅุจููู ุฅุณูู ุงุนูููู ุฅุจููู ุงูุฑููุฒุงุฒ ุงูุฌุฒุฑูโ, IPA:ย [รฆldสรฆzรฆriห]) was a Muslim polymath: a scholar, inventor, mechanical engineer, artisan, artist and mathematician. He is best known for writing The Book of Knowledge of Ingenious Mechanical Devices (Arabic: ูุชุงุจ ูู ู ุนุฑูุฉ ุงูุญูู ุงูููุฏุณูุฉโ, romanized:ย Kitab fi ma'rifat al-hiyal al-handasiya, lit.ย 'Book in knowledge of engineering tricks') in 1206, where he described 100 mechanical devices, some 80 of which are trick vessels of various kinds, along with instructions on how to construct them.
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- "Al-Jazari" | 2014-09-07 | 286 Upvotes 122 Comments
๐ Psychedelics in problem-solving experiment
Psychedelic agents in creative problem-solving experiment was a study designed to evaluate whether the use of a psychedelic substance with supportive setting can lead to improvement of performance in solving professional problems. The altered performance was measured by subjective reports, questionnaires, the obtained solutions for the professional problems and psychometric data using the Purdue Creativity, the Miller Object Visualization, and the Witkins Embedded Figures tests. This experiment was a pilot that was to be followed by control studies as part of exploratory studies on uses for psychedelic drugs, that were interrupted early in 1966 when the Food and Drug Administration declared a moratorium on research with human subjects, as a strategy in combating illicit use.
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- "Psychedelics in problem-solving experiment" | 2014-08-30 | 167 Upvotes 47 Comments
๐ Hilbert's 24th problem
Hilbert's twenty-fourth problem is a mathematical problem that was not published as part of the list of 23 problems known as Hilbert's problems but was included in David Hilbert's original notes. The problem asks for a criterion of simplicity in mathematical proofs and the development of a proof theory with the power to prove that a given proof is the simplest possible.
The 24th problem was rediscovered by German historian Rรผdiger Thiele in 2000, noting that Hilbert did not include the 24th problem in the lecture presenting Hilbert's problems or any published texts. Hilbert's friends and fellow mathematicians Adolf Hurwitz and Hermann Minkowski were closely involved in the project but did not have any knowledge of this problem.
This is the full text from Hilbert's notes given in Rรผdiger Thiele's paper. The section was translated by Rรผdiger Thiele.
The 24th problem in my Paris lecture was to be: Criteria of simplicity, or proof of the greatest simplicity of certain proofs. Develop a theory of the method of proof in mathematics in general. Under a given set of conditions there can be but one simplest proof. Quite generally, if there are two proofs for a theorem, you must keep going until you have derived each from the other, or until it becomes quite evident what variant conditions (and aids) have been used in the two proofs. Given two routes, it is not right to take either of these two or to look for a third; it is necessary to investigate the area lying between the two routes. Attempts at judging the simplicity of a proof are in my examination of syzygies and syzygies [Hilbert misspelled the word syzygies] between syzygies (see Hilbert 42, lectures XXXIIโXXXIX). The use or the knowledge of a syzygy simplifies in an essential way a proof that a certain identity is true. Because any process of addition [is] an application of the commutative law of addition etc. [and because] this always corresponds to geometric theorems or logical conclusions, one can count these [processes], and, for instance, in proving certain theorems of elementary geometry (the Pythagoras theorem, [theorems] on remarkable points of triangles), one can very well decide which of the proofs is the simplest. [Author's note: Part of the last sentence is not only barely legible in Hilbert's notebook but also grammatically incorrect. Corrections and insertions that Hilbert made in this entry show that he wrote down the problem in haste.]
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- "Hilbert's 24th problem" | 2014-08-19 | 29 Upvotes 15 Comments
๐ Indefinite lifespan
Life extension is the idea of extending the human lifespan, either modestly โ through improvements in medicine โ or dramatically by increasing the maximum lifespan beyond its generally settled limit of 125 years. The ability to achieve such dramatic changes, however, does not currently exist.
Some researchers in this area, and "life extensionists", "immortalists" or "longevists" (those who wish to achieve longer lives themselves), believe that future breakthroughs in tissue rejuvenation, stem cells, regenerative medicine, molecular repair, gene therapy, pharmaceuticals, and organ replacement (such as with artificial organs or xenotransplantations) will eventually enable humans to have indefinite lifespans (agerasia) through complete rejuvenation to a healthy youthful condition. The ethical ramifications, if life extension becomes a possibility, are debated by bioethicists.
The sale of purported anti-aging products such as supplements and hormone replacement is a lucrative global industry. For example, the industry that promotes the use of hormones as a treatment for consumers to slow or reverse the aging process in the US market generated about $50ย billion of revenue a year in 2009. The use of such products has not been proven to be effective or safe.
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- "Indefinite lifespan" | 2014-08-16 | 22 Upvotes 8 Comments
๐ LOLCODE
LOLCODE is an esoteric programming language inspired by lolspeak, the language expressed in examples of the lolcat Internet meme. The language was created in 2007 by Adam Lindsay, researcher at the Computing Department of Lancaster University.
The language is not clearly defined in terms of operator priorities and correct syntax, but several functioning interpreters and compilers exist. One interpretation of the language has been proven Turing-complete.
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- "LOLCODE" | 2014-08-08 | 47 Upvotes 25 Comments
๐ List of Java virtual machines
This article provides non-exhaustive lists of Java SE Java virtual machines (JVMs). It does not include a large number of Java ME vendors. Note that Java EE runs on the standard Java SE JVM but that some vendors specialize in providing a modified JVM optimized for Java EE applications. A large amount of Java development work takes place on Windows, Solaris, Linux and FreeBSD, primarily with the Oracle JVMs. Note the further complication of different 32-bit/64-bit varieties.
The primary reference Java VM implementation is HotSpot, produced by Oracle Corporation.
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- "List of Java virtual machines" | 2014-08-07 | 25 Upvotes 7 Comments
๐ List of people who have petitioned for the right to be forgotten
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- "List of people who have petitioned for the right to be forgotten" | 2014-08-07 | 18 Upvotes 7 Comments
๐ Zoopharmacognosy
Zoopharmacognosy is a behaviour in which non-human animals apparently self-medicate by selecting and ingesting or topically applying plants, soils, insects, and psychoactive drugs to prevent or reduce the harmful effects of pathogens and toxins. The term derives from Greek roots zoo ("animal"), pharmacon ("drug, medicine"), and gnosy ("knowing").
An example of zoopharmacognosy occurs when dogs eat grass to induce vomiting. However, the behaviour is more diverse than this. Animals ingest or apply non-foods such as clay, charcoal and even toxic plants and invertebrates, apparently to prevent parasitic infestation or poisoning.
Whether animals truly self-medicate remains a somewhat controversial subject because early evidence is mostly circumstantial or anecdotal, however, more recent examinations have adopted an experimental, hypothesis-driven approach.
The methods by which animals self-medicate vary, but can be classified according to function as prophylactic (preventative, before infection or poisoning) or therapeutic (after infection, to combat the pathogen or poisoning). The behaviour is believed to have widespread adaptive significance.
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- "Zoopharmacognosy" | 2014-08-07 | 32 Upvotes 6 Comments
๐ Casimir Effect
In quantum field theory, the Casimir effect and the CasimirโPolder force are physical forces arising from a quantized field. They are named after the Dutch physicist Hendrik Casimir who predicted them in 1948.
The Casimir effect can be understood by the idea that the presence of conducting metals and dielectrics alters the vacuum expectation value of the energy of the second quantized electromagnetic field. Since the value of this energy depends on the shapes and positions of the conductors and dielectrics, the Casimir effect manifests itself as a force between such objects.
Any medium supporting oscillations has an analogue of the Casimir effect. For example, beads on a string as well as plates submerged in turbulent water or gas illustrate the Casimir force.
In modern theoretical physics, the Casimir effect plays an important role in the chiral bag model of the nucleon; in applied physics it is significant in some aspects of emerging microtechnologies and nanotechnologies.
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- "Casimir Effect" | 2014-08-03 | 29 Upvotes 2 Comments
๐ Saccadic masking
Saccadic masking, also known as (visual) saccadic suppression, is the phenomenon in visual perception where the brain selectively blocks visual processing during eye movements in such a way that neither the motion of the eye (and subsequent motion blur of the image) nor the gap in visual perception is noticeable to the viewer.
The phenomenon was first described by Erdmann and Dodge in 1898, when it was noticed during unrelated experiments that an observer could never see the motion of their own eyes. This can easily be duplicated by looking into a mirror, and looking from one eye to another. The eyes can never be observed in motion, yet an external observer clearly sees the motion of the eyes.
The phenomenon is often used to help explain a temporal illusion by the name of chronostasis, which momentarily occurs following a rapid eye-movement.
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- "Saccadic masking" | 2014-08-03 | 10 Upvotes 1 Comments