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The photoacoustic effect or optoacoustic effect is the formation of sound waves following light absorption in a material sample. In order to obtain this effect the light intensity must vary, either periodically (modulated light) or as a single flash (pulsed light). The photoacoustic effect is quantified by measuring the formed sound (pressure changes) with appropriate detectors, such as microphones or piezoelectric sensors. The time variation of the electric output (current or voltage) from these detectors is the photoacoustic signal. These measurements are useful to determine certain properties of the studied sample. For example, in photoacoustic spectroscopy, the photoacoustic signal is used to obtain the actual absorption of light in either opaque or transparent objects. It is useful for substances in extremely low concentrations, because very strong pulses of light from a laser can be used to increase sensitivity and very narrow wavelengths can be used for specificity. Furthermore, photoacoustic measurements serve as a valuable research tool in the study of the heat evolved in photochemical reactions (see: photochemistry), particularly in the study of photosynthesis.

Most generally, electromagnetic radiation of any kind can give rise to a photoacoustic effect. This includes the whole range of electromagnetic frequencies, from gamma radiation and X-rays to microwave and radio. Still, much of the reported research and applications, utilizing the photoacoustic effect, is concerned with the near ultraviolet/visible and infrared spectral regions.

🔗 Neuroscience

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.

🔗 Philosophy 🔗 Philosophy/Social and political philosophy 🔗 Football

Three-sided football (often referred to as 3SF) is a variation of association football played with three teams instead of the usual two. It was devised by the Danish Situationist Asger Jorn to explain his notion of triolectics, his refinement on the Marxian concept of dialectics, as well as to disrupt one's everyday idea of football. Played on a hexagonal pitch [1], the game can be adapted for similarity to soccer as well as other versions of football.

Unlike conventional football, where the winner is determined by the highest scoring of the two teams, in three-sided football the winning team is that which concedes the fewest goals.

🔗 Television 🔗 Media

TV-B-Gone is a universal remote control device for turning off a large majority—about 85%—of the available brands of television sets in 2015. It was created to allow people in a public place to turn off nearby television sets. Its inventor has referred to it as "an environmental management device". The device is part of a key-chain, and, like other remote devices, is battery-powered. Although it can require up to 72 seconds for the device to find the proper code for a particular television receiver, the most popular televisions turn off in the first few seconds.

🔗 Mathematics 🔗 Game theory

Fair cake-cutting is a kind of fair division problem. The problem involves a heterogeneous resource, such as a cake with different toppings, that is assumed to be divisible – it is possible to cut arbitrarily small pieces of it without destroying their value. The resource has to be divided among several partners who have different preferences over different parts of the cake, i.e., some people prefer the chocolate toppings, some prefer the cherries, some just want as large a piece as possible. The division should be unanimously fair – each person should receive a piece believed to be a fair share.

The "cake" is only a metaphor; procedures for fair cake-cutting can be used to divide various kinds of resources, such as land estates, advertisement space or broadcast time.

The prototypical procedure for fair cake-cutting is divide and choose, which is mentioned in the book of Genesis. It solves the fair division problem for two people. The modern study of fair cake-cutting was initiated during World War II, when Hugo Steinhaus asked his students Stefan Banach and Bronisław Knaster to find a generalization of divide-and-choose to three or more people. They developed the last diminisher procedure. Today, fair cake-cutting is the subject of intense research in mathematics, computer science, economics and political science.

🔗 Computing

The blinking twelve problem is a term used in software design. It usually refers to features in software or computer systems which are rendered unusable to most users by the complexity of the interface to them.

The usage emanates from the 'clock' feature provided on many VCRs manufactured in the late 1980s or early 1990s. The clock could be set by using a combination of buttons provided on the VCR in a specific sequence that was found complicated by most users. As a result, VCR users were known to seldom set the time on the VCR clock. This resulted in the default time of '12:00' blinking on the VCR display at all times of the day, which is the origin of this term.

"In most surveys, the majority of people have never time-shifted just because they don't know how to program their machines," said Tom Adams, a television analyst for Paul Kagan Associates, a media research firm, in 1990.

In software, 'the blinking twelve problem' thus refers to any situation in which features or functions of a program go unused for reasons that the designers never anticipated, largely because developers were unable to anticipate the level of understanding the users would have of the technology. The term may also refer to the challenge faced by developers of addressing the real causes of users' difficulties, as well as the challenge of providing helpful documentation or technical support without knowing beforehand how well the user understands their own problem.

In other instances, it can be used to reference the lack of basic user-friendly features in complex systems; stemming from the lack of a backup battery to keep the clock setting in a $300 VCR during even the briefest power interruption, when a $10 clock would have one.

The terms is usually used mostly by geeks, often in discussion forums. The term appears in the 1999 essay In the Beginning... Was the Command Line by Neal Stephenson.

🔗 Military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry 🔗 Iraq 🔗 Military history/Middle Eastern military history

Project Babylon was a space gun project commissioned by then Iraqi president Saddam Hussein. It involved building a series of "superguns". The design was based on research from the 1960s Project HARP led by the Canadian artillery expert Gerald Bull. There were most likely four different devices in the program.

The project began in 1988; it was halted in 1990 after Bull was assassinated, and parts of the superguns were seized in transit around Europe. The components that remained in Iraq were destroyed by the United Nations after the 1991 Persian Gulf War.

🔗 Aviation 🔗 Military history 🔗 Military history/Military aviation 🔗 Aviation/Aviation accident 🔗 Wiltshire 🔗 Military history/European military history 🔗 Military history/British military history

On 22 July 1966 Walter "Taffy" Holden, an engineer in command of No. 33 Maintenance Unit RAF with limited experience flying small single-engine trainer aircraft, inadvertently engaged the afterburner of a Mach 2.0-capable English Electric Lightning during ground testing. Unable to disengage the afterburner, Holden ran down the runway, narrowly missing a crossing fuel bowser and a de Havilland Comet taking off, before taking off himself. Flying without a helmet or canopy, the ejection seat disabled, and the landing gear locked down, Holden aborted his first two landing attempts. He landed on his third approach, striking the runway with the aircraft's tail as he adopted in his flare the attitude of a taildragger aircraft. The aircraft returned to service, and was subsequently acquired by the Imperial War Museum Duxford.

🔗 Finance & Investment 🔗 Economics 🔗 Business 🔗 Cooperatives

A credit union, a type of financial institution similar to a commercial bank, is a member-owned nonprofit financial cooperative. Credit unions generally provide services to members similar to retail banks, including deposit accounts, provision of credit, and other financial services. In several African countries, credit unions are commonly referred to as SACCOs (Savings and Credit Co-Operatives).

Worldwide, credit union systems vary significantly in their total assets and average institution asset size, ranging from volunteer operations with a handful of members to institutions with hundreds of thousands of members and assets worth billions of US dollars. In 2018, the number of members in credit unions worldwide was 274 million, with nearly 40 million members having been added since 2016.

Leading up to the financial crisis of 2007–2008, commercial banks engaged in approximately five times more subprime lending relative to credit unions and were two and a half times more likely to fail during the crisis. American credit unions more than doubled lending to small businesses between 2008 and 2016, from $30 billion to $60 billion, while lending to small businesses overall during the same period declined by around $100 billion. In the US, public trust in credit unions stands at 60%, compared to 30% for big banks. Furthermore, small businesses are 80% less likely to be dissatisfied with a credit union than with a big bank.

"Natural-person credit unions" (also called "retail credit unions" or "consumer credit unions") serve individuals, as distinguished from "corporate credit unions", which serve other credit unions.

🔗 Paranormal

The Eltanin Antenna is an object photographed on the sea floor by the Antarctic oceanographic research ship USNS Eltanin in 1964, while photographing the sea bottom west of Cape Horn.

Due to its regular antenna-like structure and upright position on the seafloor at a depth of 3,904 metres (12,808 ft), some proponents of fringe and UFO-related theories including Bruce Cathie have suggested that it might be an extraterrestrial artifact. Other authorities have suggested that the object photographed by the Eltanin was an unusual carnivorous sponge, Chondrocladia concrescens (formerly Cladorhiza concrescens).