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🔗 Computing 🔗 Computing/Software 🔗 Numismatics 🔗 Numismatics/Cryptocurrency 🔗 Cryptocurrency

Gridcoin (ticker: GRC) is an open source cryptocurrency which securely rewards volunteer computing performed on the BOINC, a distributed computing platform that is home to over 30 science projects spanning a range of scientific disciplines.

Gridcoin attempts to address and ease the environmental energy impact of cryptocurrency mining through its proof-of-research and proof-of-stake protocols, as compared to the proof of work system used by Bitcoin.

🔗 Psychology 🔗 Cognitive science

Pandemonium architecture is a theory in cognitive science that describes how visual images are processed by the brain. It has applications in artificial intelligence and pattern recognition. The theory was developed by the artificial intelligence pioneer Oliver Selfridge in 1959. It describes the process of object recognition as a hierarchical system of detection and association by a metaphorical set of "demons" sending signals to each other. This model is now recognized as the basis of visual perception in cognitive science.

Pandemonium architecture arose in response to the inability of template matching theories to offer a biologically plausible explanation of the image constancy phenomenon. Contemporary researchers praise this architecture for its elegancy and creativity; that the idea of having multiple independent systems (e.g., feature detectors) working in parallel to address the image constancy phenomena of pattern recognition is powerful yet simple. The basic idea of the pandemonium architecture is that a pattern is first perceived in its parts before the "whole".

Pandemonium architecture was one of the first computational models in pattern recognition. Although not perfect, the pandemonium architecture influenced the development of modern connectionist, artificial intelligence, and word recognition models.

🔗 Companies

Geneva Freeport (French: Ports Francs et Entrepôts de Genève SA) is a warehouse complex in Geneva, Switzerland, for the storage of art and other valuables and collectibles. The free port has been described as the "premier place" to store valuable works of art, and users "come for the security and stay for the tax treatment."

It is the oldest and largest freeport facility, and the one with the most artworks, with an estimated art collection value of US$100 billion. According to Jean-René Saillard of the British Fine Art Fund, "It would be probably the best museum in the world if it was a museum."

🔗 Sports 🔗 Basketball

Height can significantly influence success in sports, depending on how the design of the sport is linked to factors that are height-biased due to physics and biology. The balance of the intricate array of links will determine the degree to which height plays a role in success, if any.

🔗 Economics

An Information cascade or informational cascade is a phenomenon described in behavioral economics and network theory in which a number of people make the same decision in a sequential fashion. It is similar to, but distinct from herd behavior.

An information cascade is generally accepted as a two-step process. For a cascade to begin an individual must encounter a scenario with a decision, typically a binary one. Second, outside factors can influence this decision (typically, through the observation of actions and their outcomes of other individuals in similar scenarios).

The two-step process of an informational cascade can be broken down into five basic components:

1. There is a decision to be made – for example; whether to adopt a new technology, wear a new style of clothing, eat in a new restaurant, or support a particular political position

2. A limited action space exists (e.g. an adopt/reject decision)

3. People make the decision sequentially, and each person can observe the choices made by those who acted earlier

4. Each person has some information aside from their own that helps guide their decision

5. A person can't directly observe the outside information that other people know, but he or she can make inferences about this information from what they do

Social perspectives of cascades, which suggest that agents may act irrationally (e.g., against what they think is optimal) when social pressures are great, exist as complements to the concept of information cascades. More often the problem is that the concept of an information cascade is confused with ideas that do not match the two key conditions of the process, such as social proof, information diffusion, and social influence. Indeed, the term information cascade has even been used to refer to such processes.

🔗 United States 🔗 Germany 🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry 🔗 Military history/Intelligence 🔗 United Kingdom 🔗 Military history/World War II 🔗 Military history/German military history 🔗 Military history/European military history 🔗 Military history/British military history

Operation Epsilon was the codename of a program in which Allied forces near the end of World War II detained ten German scientists who were thought to have worked on Nazi Germany's nuclear program. The scientists were captured between May 1 and June 30, 1945, as part of the Allied Alsos Mission, mainly as part of its Operation Big sweep through southwestern Germany.

They were interned at Farm Hall, a bugged house in Godmanchester, near Cambridge, England, from July 3, 1945, to January 3, 1946. The primary goal of the program was to determine how close Nazi Germany had been to constructing an atomic bomb by listening to their conversations.

🔗 India 🔗 Numismatics

The Indian rupee sign (sign: ₹; code: INR) is the currency symbol for the Indian rupee, the official currency of India. Designed by Udaya Kumar, it was presented to the public by the Government of India on 15 July 2010, following its selection through an "open" competition among Indian residents. Before its adoption, the most commonly used symbols for the rupee were Rs, Re or, in texts in Indian languages, an appropriate abbreviation in the language used.

The design is based on the Devanagari letter "र" (ra) with a double horizontal line at the top. It also resembles the Latin capital letter "R", especially R rotunda (Ꝛ).

The Unicode character for the Indian rupee sign is U+20B9 ₹ INDIAN RUPEE SIGN. Other countries that use a rupee, such as Sri Lanka, Pakistan and Nepal, still use the generic U+20A8 ₨ RUPEE SIGN character.

🔗 Physics

The quantum Zeno effect (also known as the Turing paradox) is a feature of quantum-mechanical systems allowing a particle's time evolution to be slowed down by measuring it frequently enough with respect to some chosen measurement setting.

Sometimes this effect is interpreted as "a system cannot change while you are watching it". One can "freeze" the evolution of the system by measuring it frequently enough in its known initial state. The meaning of the term has since expanded, leading to a more technical definition, in which time evolution can be suppressed not only by measurement: the quantum Zeno effect is the suppression of unitary time evolution in quantum systems provided by a variety of sources: measurement, interactions with the environment, stochastic fields, among other factors. As an outgrowth of study of the quantum Zeno effect, it has become clear that applying a series of sufficiently strong and fast pulses with appropriate symmetry can also decouple a system from its decohering environment.

The name comes from Zeno's arrow paradox, which states that because an arrow in flight is not seen to move during any single instant, it cannot possibly be moving at all. The first rigorous and general derivation of the quantum Zeno effect was presented in 1974 by Degasperis, Fonda, and Ghirardi, although it had previously been described by Alan Turing. The comparison with Zeno's paradox is due to a 1977 article by George Sudarshan and Baidyanath Misra.

According to the reduction postulate, each measurement causes the wavefunction to collapse to an eigenstate of the measurement basis. In the context of this effect, an observation can simply be the absorption of a particle, without the need of an observer in any conventional sense. However, there is controversy over the interpretation of the effect, sometimes referred to as the "measurement problem" in traversing the interface between microscopic and macroscopic objects.

Another crucial problem related to the effect is strictly connected to the time–energy indeterminacy relation (part of the indeterminacy principle). If one wants to make the measurement process more and more frequent, one has to correspondingly decrease the time duration of the measurement itself. But the request that the measurement last only a very short time implies that the energy spread of the state in which reduction occurs becomes increasingly large. However, the deviations from the exponential decay law for small times is crucially related to the inverse of the energy spread, so that the region in which the deviations are appreciable shrinks when one makes the measurement process duration shorter and shorter. An explicit evaluation of these two competing requests shows that it is inappropriate, without taking into account this basic fact, to deal with the actual occurrence and emergence of Zeno's effect.

Closely related (and sometimes not distinguished from the quantum Zeno effect) is the watchdog effect, in which the time evolution of a system is affected by its continuous coupling to the environment.

🔗 Computing

Lambda lifting is a meta-process that restructures a computer program so that functions are defined independently of each other in a global scope. An individual "lift" transforms a local function into a global function. It is a two step process, consisting of;

• Eliminating free variables in the function by adding parameters.
• Moving functions from a restricted scope to broader or global scope.

The term "lambda lifting" was first introduced by Thomas Johnsson around 1982 and was historically considered as a mechanism for implementing functional programming languages. It is used in conjunction with other techniques in some modern compilers.

Lambda lifting is not the same as closure conversion. It requires all call sites to be adjusted (adding extra arguments to calls) and does not introduce a closure for the lifted lambda expression. In contrast, closure conversion does not require call sites to be adjusted but does introduce a closure for the lambda expression mapping free variables to values.

The technique may be used on individual functions, in code refactoring, to make a function usable outside the scope in which it was written. Lambda lifts may also be repeated, in order to transform the program. Repeated lifts may be used to convert a program written in lambda calculus into a set of recursive functions, without lambdas. This demonstrates the equivalence of programs written in lambda calculus and programs written as functions. However it does not demonstrate the soundness of lambda calculus for deduction, as the eta reduction used in lambda lifting is the step that introduces cardinality problems into the lambda calculus, because it removes the value from the variable, without first checking that there is only one value that satisfies the conditions on the variable (see Curry's paradox).

Lambda lifting is expensive on processing time for the compiler. An efficient implementation of lambda lifting is ${\displaystyle O(n^{2})}$ on processing time for the compiler.

In the untyped lambda calculus, where the basic types are functions, lifting may change the result of beta reduction of a lambda expression. The resulting functions will have the same meaning, in a mathematical sense, but are not regarded as the same function in the untyped lambda calculus. See also intensional versus extensional equality.

The reverse operation to lambda lifting is lambda dropping.

Lambda dropping may make the compilation of programs quicker for the compiler, and may also increase the efficiency of the resulting program, by reducing the number of parameters, and reducing the size of stack frames. However it makes a function harder to re-use. A dropped function is tied to its context, and can only be used in a different context if it is first lifted.

🔗 China/Chinese history 🔗 China 🔗 Toys

The bamboo-copter, also known as the bamboo dragonfly or Chinese top (Chinese zhuqingting (竹蜻蜓), Japanese taketonbo 竹蜻蛉), is a toy helicopter rotor that flies up when its shaft is rapidly spun. This helicopter-like top originated in Jin dynasty China around 320 AD, and was the object of early experiments by English engineer George Cayley, the inventor of modern aeronautics.

In China, the earliest known flying toys consisted of feathers at the end of a stick, which was rapidly spun between the hands and released into flight. "While the Chinese top was no more than a toy, it is perhaps the first tangible device of what we may understand as a helicopter."

The Jin dynasty Daoist philosopher Ge Hong's (c. 317) book Baopuzi (抱樸子 "Master Who Embraces Simplicity") mentioned a flying vehicle in what Joseph Needham calls "truly an astonishing passage".

Some have made flying cars [feiche 飛車] with wood from the inner part of the jujube tree, using ox-leather (straps) fastened to returning blades so as to set the machine in motion [huan jian yi yin chiji 環劍以引其機]. Others have had the idea of making five snakes, six dragons and three oxen, to meet the "hard wind" [gangfeng 罡風] and ride on it, not stopping until they have risen to a height of forty li. That region is called [Taiqing 太清] (the purest of empty space). There the [qi] is extremely hard, so much so that it can overcome (the strength of) human beings. As the Teacher says: "The kite (bird) flies higher and higher spirally, and then only needs to stretch its two wings, beating the air no more, in order to go forward by itself. This is because it starts gliding (lit. riding) on the 'hard wind' [gangqi 罡炁]. Take dragons, for example; when they first rise they go up using the clouds as steps, and after they have attained a height of forty li then they rush forward effortlessly (lit. automatically) (gliding)." This account comes from the adepts [xianren 仙人], and is handed down to ordinary people, but they are not likely to understand it.

Needham concludes that Ge Hong was describing helicopter tops because "'returning (or revolving) blades' can hardly mean anything else, especially in close association with a belt or strap"; and suggests that "snakes", "dragons", and "oxen" refer to shapes of man-lifting kites. Other scholars interpret this Baopuzi passage mythologically instead of literally, based on its context's mentioning fantastic flights through chengqiao (乘蹻 "riding on tiptoe/stilts") and xian (仙 "immortal; adept") techniques. For instance, "If you can ride the arches of your feet, you will be able to wander anywhere in the world without hindrance from mountains or rivers … Whoever takes the correct amulet and gives serious thought to the process may travel a thousand miles by concentrating his thoughts for one double hour." Compare this translation.

Some build a flying vehicle from the pith of the jujube tree and have it drawn by a sword with a thong of buffalo hide at the end of its grip. Others let their thoughts dwell on the preparation of a joint rectangle from five serpents, six dragons, and three buffaloes, and mount in this for forty miles to the region known as Paradise.

This Chinese helicopter toy was introduced into Europe and "made its earliest appearances in Renaissance European paintings and in the drawings of Leonardo da Vinci." The toy helicopter appears in a c. 1460 French picture of the Madonna and Child at the Musée du Palais de Tesse’ in Mans depicting the Child holding a toy copter sitting in Mary’s lap next to St Benôit (unknown artist), and in a 16th-century stained glass panel at the Victoria and Albert Museum in London. A picture from c. 1560 by Pieter Breughel the Elder at the Kunsthistorisches Museum in Vienna, Children's Games, depicts a helicopter top with three airscrews.

"The helicopter top in China led to nothing but amusement and pleasure, but fourteen hundred years later it was to be one of the key elements in the birth of modern aeronautics in the West." Early Western scientists developed flying machines based upon the original Chinese model. The Russian polymath Mikhail Lomonosov developed a spring-driven coaxial rotor in 1743, and the French naturalist Christian de Launoy created a bow drill device with contra-rotating feather propellers.

In 1792, George Cayley began experimenting with helicopter tops, which he later called "rotary wafts" or "elevating fliers". His landmark (1809) article "On Aerial Navigation" pictured and described a flying model with two propellers (constructed from corks and feathers) powered by a whalebone bow drill. "In 1835 Cayley remarked that while the original toy would rise no more than about 20 or 25 feet (6 or 7.5 metres), his improved models would 'mount upward of 90 ft (27 metres) into the air'. This then was the direct ancestor of the helicopter rotor and the aircraft propeller."

Discussing the history of Chinese inventiveness, the British scientist, sinologist, and historian Joseph Needham wrote, "Some inventions seem to have arisen merely from a whimsical curiosity, such as the 'hot air balloons' made from eggshells which did not lead to any aeronautical use or aerodynamic discoveries, or the zoetrope which did not lead onto the kinematograph, or the helicopter top which did not lead to the helicopter."