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🔗 Business 🔗 Politics 🔗 Psychology

In the Abilene paradox, a group of people collectively decide on a course of action that is counter to the preferences of many or all of the individuals in the group. It involves a common breakdown of group communication in which each member mistakenly believes that their own preferences are counter to the group's and, therefore, does not raise objections. A common phrase relating to the Abilene paradox is a desire not to "rock the boat". This differs from groupthink in that the Abilene paradox is characterized by an inability to manage agreement.

🔗 Military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry 🔗 Medicine 🔗 Chemicals 🔗 Occupational Safety and Health 🔗 Military history/World War I 🔗 Medicine/Toxicology

Chloropicrin, also known as PS and nitrochloroform, is a chemical compound currently used as a broad-spectrum antimicrobial, fungicide, herbicide, insecticide, and nematicide. It was used as a poison gas in World War I. Its chemical structural formula is Cl₃CNO₂.

🔗 Military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry 🔗 Military history/German military history 🔗 Firearms 🔗 Military history/European military history

The Heckler & Koch P11 is an underwater firearm developed in 1976 by Heckler & Koch. It has five barrels and each fires a 7.62×36mm dart electrically. Loading is by means of a five-round case. The design resembles that of a pepper-box firearm.

🔗 Soviet Union 🔗 Russia 🔗 History 🔗 Russia/sports and games in Russia 🔗 Gymnastics

The Korbut flip is a gymnastics skill performed on either of two different apparatus. Both were first performed internationally by the Soviet gymnast Olga Korbut.

The more spectacular version of the skill used to be performed on the uneven bars, where the gymnast, from a stand on the high bar, performs a back flip and regrasps the bar. Korbut performed the move at the 1972 Summer Olympics, where it was the first backward release move performed on the uneven bars in international competition. In 1977, Soviet gymnast Elena Mukhina modified the flip by adding a full twist. The movement was later modified in the 1980s when it was performed towards the low bar; that is, the gymnast's flip takes place above the low bar. The Code of Points was later modified to ban standing on the high bar during routines.

The skill is also performed on the balance beam. The move is performed from a standing position and is landed in a straddled position on the beam. This movement has been modified to include twists and piked or tucked legs and is frequently performed in sequence with other movements. Unlike its counterpart on the uneven bars, the Korbut flip on beam is today considered a relatively simple skill, valued at only a "B" level in the 2017 Code of Points.

Other gymnasts who have performed the skill's uneven bars variation include Radka Zemanova (1980), Steffi Kraker (1977), Emily May (1981), Lyubov Bogdanova (1974) and Natalia Shaposhnikova (1976).

🔗 United States 🔗 New York City

This is a list of the longest-lasting incandescent light bulbs.

🔗 Computing 🔗 Geography

Null Island is a name for the area around the point where the prime meridian and the equator cross, located in international waters in the Gulf of Guinea (Atlantic Ocean) off the west African coast. In the WGS84 datum, this is at zero degrees latitude and longitude (0°N 0°E), and is the location of a buoy. The name 'Null Island' serves as both a joke based around the suppositional existence of an island there, and also as a name to which coordinates erroneously set to 0,0 are assigned in placenames databases in order to more easily find and fix them. The nearest land is a small islet offshore of Ghana, between Akwidaa and Dixcove at 4°45′30″N 1°58′33″W, 307.8 nmi (354.2 mi; 570.0 km) to the north.

🔗 Mathematics

The medieval Cistercian numerals, or "ciphers" in nineteenth-century parlance, were developed by the Cistercian monastic order in the early thirteenth century at about the time that Arabic numerals were introduced to northwestern Europe. They are more compact than Arabic or Roman numerals, with a single glyph able to indicate any integer from 1 to 9,999.

Digits are based on a horizontal or vertical stave, with the position of the digit on the stave indicating its place value (units, tens, hundreds or thousands). These digits are compounded on a single stave to indicate more complex numbers. The Cistercians eventually abandoned the system in favor of the Arabic numerals, but marginal use outside the order continued until the early twentieth century.

🔗 Robotics 🔗 Electronics

Surface-mount technology (SMT) component placement systems, commonly called pick-and-place machines or P&Ps, are robotic machines which are used to place surface-mount devices (SMDs) onto a printed circuit board (PCB). They are used for high speed, high precision placing of a broad range of electronic components, like capacitors, resistors, integrated circuits onto the PCBs which are in turn used in computers, consumer electronics as well as industrial, medical, automotive, military and telecommunications equipment. Similar equipment exists for through-hole components. This type of equipment is sometimes also used to package microchips using the flip chip method.

🔗 Mathematics 🔗 Statistics

Itô calculus, named after Kiyosi Itô, extends the methods of calculus to stochastic processes such as Brownian motion (see Wiener process). It has important applications in mathematical finance and stochastic differential equations.

The central concept is the Itô stochastic integral, a stochastic generalization of the Riemann–Stieltjes integral in analysis. The integrands and the integrators are now stochastic processes:

${\displaystyle Y_{t}=\int _{0}^{t}H_{s}\,dX_{s},}$

where H is a locally square-integrable process adapted to the filtration generated by X (Revuz & Yor 1999, Chapter IV), which is a Brownian motion or, more generally, a semimartingale. The result of the integration is then another stochastic process. Concretely, the integral from 0 to any particular t is a random variable, defined as a limit of a certain sequence of random variables. The paths of Brownian motion fail to satisfy the requirements to be able to apply the standard techniques of calculus. So with the integrand a stochastic process, the Itô stochastic integral amounts to an integral with respect to a function which is not differentiable at any point and has infinite variation over every time interval. The main insight is that the integral can be defined as long as the integrand H is adapted, which loosely speaking means that its value at time t can only depend on information available up until this time. Roughly speaking, one chooses a sequence of partitions of the interval from 0 to t and constructs Riemann sums. Every time we are computing a Riemann sum, we are using a particular instantiation of the integrator. It is crucial which point in each of the small intervals is used to compute the value of the function. The limit then is taken in probability as the mesh of the partition is going to zero. Numerous technical details have to be taken care of to show that this limit exists and is independent of the particular sequence of partitions. Typically, the left end of the interval is used.

Important results of Itô calculus include the integration by parts formula and Itô's lemma, which is a change of variables formula. These differ from the formulas of standard calculus, due to quadratic variation terms.

In mathematical finance, the described evaluation strategy of the integral is conceptualized as that we are first deciding what to do, then observing the change in the prices. The integrand is how much stock we hold, the integrator represents the movement of the prices, and the integral is how much money we have in total including what our stock is worth, at any given moment. The prices of stocks and other traded financial assets can be modeled by stochastic processes such as Brownian motion or, more often, geometric Brownian motion (see Black–Scholes). Then, the Itô stochastic integral represents the payoff of a continuous-time trading strategy consisting of holding an amount H_t of the stock at time t. In this situation, the condition that H is adapted corresponds to the necessary restriction that the trading strategy can only make use of the available information at any time. This prevents the possibility of unlimited gains through clairvoyance: buying the stock just before each uptick in the market and selling before each downtick. Similarly, the condition that H is adapted implies that the stochastic integral will not diverge when calculated as a limit of Riemann sums (Revuz & Yor 1999, Chapter IV).

🔗 Typography

A California job case is a kind of type case: a compartmentalized wooden box used to store movable type used in letterpress printing. It was the most popular and accepted of the job case designs in America. The California job case took its name from the Pacific Coast location of the foundries that made the case popular.

The defining characteristic of the California job case is the layout, documented by J. L. Ringwalt in the American Encyclopaedia of Printing in 1871, as used by San Francisco printers. This modification of a previously popular case, the Italic, it was claimed reduced the compositor's hand travel as he set the pieces of type into his composing stick by more than half a mile per day. In the previous convention, upper- and lowercase type were kept in separate cases, or trays. This is why capital letters are called uppercase and the minuscules are lowercase. The combined case became popular during the western expansion of the United States in the 19th century.