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🔗 Computer science

The Q notation is a succinct way to specify the parameters of a binary fixed point number format. A number of other notations have been used for the same purpose.

🔗 Computing 🔗 Computing/Computer science

m4 is a general-purpose macro processor included in all UNIX-like operating systems, and is a component of the POSIX standard.

The language was designed by Brian Kernighan and Dennis Ritchie for the original versions of UNIX. It is an extension of an earlier macro processor m3, written by Ritchie for an unknown AP-3 minicomputer.

The macro preprocessor operates as a text-replacement tool. It is employed to re-use text templates, typically in computer programming applications, but also in text editing and text-processing applications. Most users require m4 as a dependency of GNU autoconf.

🔗 Poetry 🔗 Songs

"Desiderata" (Latin: "things desired") is an early 1920s prose poem by the American writer Max Ehrmann. Although he copyrighted it in 1927, he distributed copies of it without a required copyright notice during 1933 and c. 1942, thereby forfeiting his US copyright. Largely unknown in the author's lifetime, its use in devotional and spoken word recordings in 1960 and 1971 called it to the attention of the world.

🔗 Spaceflight 🔗 Physics 🔗 Astronomy 🔗 Solar System

The Pioneer anomaly or Pioneer effect was the observed deviation from predicted accelerations of the Pioneer 10 and Pioneer 11 spacecraft after they passed about 20 astronomical units (3×10⁹ km; 2×10⁹ mi) on their trajectories out of the Solar System. The apparent anomaly was a matter of much interest for many years but has been subsequently explained by an anisotropic radiation pressure caused by the spacecraft's heat loss.

Both Pioneer spacecraft are escaping the Solar System but are slowing under the influence of the Sun's gravity. Upon very close examination of navigational data, the spacecraft were found to be slowing slightly more than expected. The effect is an extremely small acceleration towards the Sun, of (8.74±1.33)×10⁻¹⁰ m/s², which is equivalent to a reduction of the outbound velocity by 1 km/h over a period of ten years. The two spacecraft were launched in 1972 and 1973. The anomalous acceleration was first noticed as early as 1980 but not seriously investigated until 1994. The last communication with either spacecraft was in 2003, but analysis of recorded data continues.

Various explanations, both of spacecraft behavior and of gravitation itself, were proposed to explain the anomaly. Over the period from 1998 to 2012, one particular explanation became accepted. The spacecraft, which are surrounded by an ultra-high vacuum and are each powered by a radioisotope thermoelectric generator (RTG), can shed heat only via thermal radiation. If, due to the design of the spacecraft, more heat is emitted in a particular direction by what is known as a radiative anisotropy, then the spacecraft would accelerate slightly in the direction opposite of the excess emitted radiation due to the recoil of thermal photons. If the excess radiation and attendant radiation pressure were pointed in a general direction opposite the Sun, the spacecraft's velocity away from the Sun would be decreasing at a rate greater than could be explained by previously recognized forces, such as gravity and trace friction due to the interplanetary medium (imperfect vacuum).

By 2012 several papers by different groups, all reanalyzing the thermal radiation pressure forces inherent in the spacecraft, showed that a careful accounting of this explains the entire anomaly; thus the cause is mundane and does not point to any new phenomenon or need for a different physical paradigm. The most detailed analysis to date, by some of the original investigators, explicitly looks at two methods of estimating thermal forces, concluding that there is "no statistically significant difference between the two estimates and [...] that once the thermal recoil force is properly accounted for, no anomalous acceleration remains."

🔗 Chess

Zugzwang (German for "compulsion to move", pronounced [ˈtsuːktsvaŋ]) is a situation found in chess and other turn-based games wherein one player is put at a disadvantage because they must make a move when they would prefer to pass and not move. The fact that the player is compelled to move means that their position will become significantly weaker. A player is said to be "in zugzwang" when any possible move will worsen their position.

Although the term is used less precisely in games such as chess, it is used specifically in combinatorial game theory to denote a move that directly changes the outcome of the game from a win to a loss. Putting the opponent in zugzwang is a common way to help the superior side win a game, and in some cases it is necessary in order to make the win possible.

The term zugzwang was used in German chess literature in 1858 or earlier, and the first known use of the term in English was by World Champion Emanuel Lasker in 1905. The concept of zugzwang was known to chess players many centuries before the term was coined, appearing in an endgame study published in 1604 by Alessandro Salvio, one of the first writers on the game, and in shatranj studies dating back to the early 9th century, over 1000 years before the first known use of the term.

Positions with zugzwang occur fairly often in chess endgames, especially in king and pawn endgames. According to John Nunn, positions of reciprocal zugzwang are surprisingly important in the analysis of endgames.

🔗 Mathematics

The number e is a mathematical constant approximately equal to 2.71828 and is the base of the natural logarithm: the unique number whose natural logarithm is equal to one. It is the limit of (1 + 1/n)ⁿ as n approaches infinity, an expression that arises in the study of compound interest. It can also be calculated as the sum of the infinite series

${\displaystyle e=\sum \limits _{n=0}^{\infty }{\frac {1}{n!}}={\frac {1}{1}}+{\frac {1}{1}}+{\frac {1}{1\cdot 2}}+{\frac {1}{1\cdot 2\cdot 3}}+\cdots }$

The constant can be characterized in many different ways. For example, it can be defined as the unique positive number a such that the graph of the function y = a^x has unit slope at x = 0. The function f(x) = e^x is called the (natural) exponential function, and is the unique exponential function equal to its own derivative. The natural logarithm, or logarithm to base e, is the inverse function to the natural exponential function. The natural logarithm of a number k > 1 can be defined directly as the area under the curve y = 1/x between x = 1 and x = k, in which case e is the value of k for which this area equals one (see image). There are alternative characterizations.

e is sometimes called Euler's number after the Swiss mathematician Leonhard Euler (not to be confused with γ, the Euler–Mascheroni constant, sometimes called simply Euler's constant), or as Napier's constant. However, Euler's choice of the symbol e is said to have been retained in his honor. The constant was discovered by the Swiss mathematician Jacob Bernoulli while studying compound interest.

The number e has eminent importance in mathematics, alongside 0, 1, π, and i. All five of these numbers play important and recurring roles across mathematics, and these five constants appear in one formulation of Euler's identity. Like the constant π, e is also irrational (i.e. it cannot be represented as ratio of integers) and transcendental (i.e. it is not a root of any non-zero polynomial with rational coefficients). The numerical value of e truncated to 50 decimal places is

🔗 Biography 🔗 France 🔗 Biography/science and academia 🔗 Biography/Actors and Filmmakers

Louis Aimé Augustin Le Prince (28 August 1841 – disappeared 16 September 1890, declared dead 16 September 1897) was a French artist and the inventor of an early motion-picture camera, possibly the first person to shoot a moving picture sequence using a single lens camera and a strip of (paper) film. He has been credited as the "Father of Cinematography", but his work did not influence the commercial development of cinema—owing at least in part to the great secrecy surrounding it.

A Frenchman who also worked in the United Kingdom and the United States, Le Prince's motion-picture experiments culminated in 1888 in Leeds, England. In October of that year, he filmed moving-picture sequences of family members in Roundhay Garden and his son playing the accordion, using his single-lens camera and Eastman's paper negative film. At some point in the following eighteen months he also made a film of Leeds Bridge. This work may have been slightly in advance of the inventions of contemporaneous moving-picture pioneers, such as the British inventors William Friese-Greene and Wordsworth Donisthorpe, and was years in advance of that of Auguste and Louis Lumière and William Kennedy Dickson (who did the moving image work for Thomas Edison).

Le Prince was never able to perform a planned public demonstration of his camera in the US because he mysteriously vanished; he was last known to be boarding a train on 16 September 1890. Multiple conspiracy theories have emerged about the reason for his disappearance, including: a murder set up by Edison, secret homosexuality, disappearance in order to start a new life, suicide because of heavy debts and failing experiments, and a murder by his brother over their mother's will. No conclusive evidence exists for any of these theories. In 2004, a police archive in Paris was found to contain a photograph of a drowned man bearing a strong resemblance to Le Prince who was discovered in the Seine just after the time of his disappearance, but it has been claimed that the body was too short to be Le Prince.

In early 1890, Edison workers had begun experimenting with using a strip of celluloid film to capture moving images. The first public results of these experiments were shown in May 1891. However, Le Prince's widow and son Adolphe were keen to advance Louis's cause as the inventor of cinematography. In 1898, Adolphe appeared as a witness for the defence in a court case brought by Edison against the American Mutoscope Company. This suit claimed that Edison was the first and sole inventor of cinematography, and thus entitled to royalties for the use of the process. Adolphe was involved in the case but was not allowed to present his father's two cameras as evidence, although films shot with cameras built according to his father's patent were presented. Eventually the court ruled in favour of Edison. A year later that ruling was overturned, but Edison then reissued his patents and succeeded in controlling the US film industry for many years.

🔗 Medicine 🔗 Biology

The blue field entoptic phenomenon is an entoptic phenomenon characterized by the appearance of tiny bright dots (nicknamed blue-sky sprites) moving quickly along undulating pathways in the visual field, especially when looking into bright blue light such as the sky. The dots are short-lived, visible for about one second or less, and traveling short distances along seemingly random, undulating paths. Some of them seem to follow the same path as other dots before them. The dots may appear elongated along the path, like tiny worms. The dots' rate of travel appears to vary in synchrony with the heartbeat: they briefly accelerate at each beat. The dots appear in the central field of view, within 15 degrees from the fixation point. The left and right eye see different, seemingly random, dot patterns; a person viewing through both eyes sees a combination of both left and right visual field disturbances. While seeing the phenomenon, lightly pressing inward on the sides of the eyeballs at the lateral canthus causes the movement to stop being fluid and the dots to move only when the heart beats.

Most people are able to see this phenomenon in the sky, although it is relatively weak in most instances; many will not notice it until asked to pay attention. The dots are highly conspicuous against any monochromatic blue background of a wavelength of around 430 nm in place of the sky. The phenomenon is also known as Scheerer's phenomenon, after the German ophthalmologist Richard Scheerer, who first drew clinical attention to it in 1924.

🔗 Japan 🔗 Paranormal 🔗 Baseball 🔗 Japan/Japanese baseball 🔗 Japan/Mythology

The Curse of the Colonel (Japanese: カーネルサンダースの呪い, romanisation: Kāneru Sandāsu no Noroi) refers to a 1985 Japanese urban legend regarding a reputed curse placed on the Japanese Kansai-based Hanshin Tigers baseball team by the ghost of deceased KFC founder and mascot Colonel Sanders.

The curse was said to be placed on the team because of the Colonel's anger over treatment of one of his store-front statues, which was thrown into the Dōtonbori River by celebrating Hanshin fans before their team's victory in the 1985 Japan Championship Series. As is common with sports-related curses, the Curse of the Colonel was used to explain the team's subsequent 18-year losing streak. Some fans believed the team would never win another Japan Series until the statue had been recovered. They have appeared in the Japan Series three times since then, losing in 2003, 2005 and 2014.

Comparisons are often made between the Hanshin Tigers and the Boston Red Sox, who were said to be under the Curse of the Bambino until they won the World Series in 2004. The "Curse of the Colonel" has also been used as a bogeyman threat to those who would divulge the secret recipe of eleven herbs and spices that result in the unique taste of his chicken.