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🔗 Computing 🔗 Libraries

The memex (originally coined "at random", though sometimes said to be a portmanteau of "memory" and "index") is the name of the hypothetical proto-hypertext system that Vannevar Bush described in his 1945 The Atlantic Monthly article "As We May Think". Bush envisioned the memex as a device in which individuals would compress and store all of their books, records, and communications, "mechanized so that it may be consulted with exceeding speed and flexibility". The memex would provide an "enlarged intimate supplement to one's memory". The concept of the memex influenced the development of early hypertext systems (eventually leading to the creation of the World Wide Web) and personal knowledge base software. The hypothetical implementation depicted by Bush for the purpose of concrete illustration was based upon a document bookmark list of static microfilm pages and lacked a true hypertext system, where parts of pages would have internal structure beyond the common textual format. Early electronic hypertext systems were thus inspired by memex rather than modeled directly upon it.

🔗 Computer science

In computer science, corecursion is a type of operation that is dual to recursion. Whereas recursion works analytically, starting on data further from a base case and breaking it down into smaller data and repeating until one reaches a base case, corecursion works synthetically, starting from a base case and building it up, iteratively producing data further removed from a base case. Put simply, corecursive algorithms use the data that they themselves produce, bit by bit, as they become available, and needed, to produce further bits of data. A similar but distinct concept is generative recursion which may lack a definite "direction" inherent in corecursion and recursion.

Where recursion allows programs to operate on arbitrarily complex data, so long as they can be reduced to simple data (base cases), corecursion allows programs to produce arbitrarily complex and potentially infinite data structures, such as streams, so long as it can be produced from simple data (base cases) in a sequence of finite steps. Where recursion may not terminate, never reaching a base state, corecursion starts from a base state, and thus produces subsequent steps deterministically, though it may proceed indefinitely (and thus not terminate under strict evaluation), or it may consume more than it produces and thus become non-productive. Many functions that are traditionally analyzed as recursive can alternatively, and arguably more naturally, be interpreted as corecursive functions that are terminated at a given stage, for example recurrence relations such as the factorial.

Corecursion can produce both finite and infinite data structures as results, and may employ self-referential data structures. Corecursion is often used in conjunction with lazy evaluation, to produce only a finite subset of a potentially infinite structure (rather than trying to produce an entire infinite structure at once). Corecursion is a particularly important concept in functional programming, where corecursion and codata allow total languages to work with infinite data structures.

🔗 United States 🔗 Law 🔗 Taxation

The Tariff Act of 1930 (codified at 19 U.S.C. ch. 4), commonly known as the Smoot–Hawley Tariff or Hawley–Smoot Tariff, was a law that implemented protectionist trade policies in the United States. Sponsored by Senator Reed Smoot, Republican, Utah] and Representative Willis C. Hawley, it was signed by President Herbert Hoover on June 17, 1930. The act raised US tariffs on over 20,000 imported goods.

The tariffs under the act, excluding duty-free imports, were the second highest in United States history, exceeded by only the Tariff of 1828. The Act prompted retaliatory tariffs by many other countries. The Act and tariffs imposed by America's trading partners in retaliation were major factors of the reduction of American exports and imports by 67% during the Great Depression. Economists and economic historians have agreed that the passage of the Smoot–Hawley Tariff worsened the effects of the Great Depression.

🔗 Economics 🔗 Law

The Brussels effect is the process of unilateral regulatory globalisation caused by the European Union de facto (but not necessarily de jure) externalising its laws outside its borders through market mechanisms.

🔗 United States/U.S. Government 🔗 United States 🔗 Cold War 🔗 Conservatism 🔗 United States/U.S. history 🔗 United States/United States Presidents

"We begin bombing in five minutes" is the last sentence of a controversial, off-the-record joke made by U.S. President Ronald Reagan in 1984, during the Cold War.

While preparing for a scheduled radio address from his vacation home in California, President Reagan joked with those present about outlawing and bombing Russia. This joke was not broadcast live, but was recorded and later leaked to the public. The Soviet Union criticized the president's joke, as did Reagan's opponent in the 1984 United States presidential election, Walter Mondale.

🔗 Physics

In quantum field theory, a false vacuum is a hypothetical vacuum that is relatively stable, but not in the most stable state possible. In this condition it is called metastable. It may last for a very long time in this state, but could eventually decay to the more stable one, an event known as false vacuum decay. The most common suggestion of how such a decay might happen in our universe is called bubble nucleation – if a small region of the universe by chance reached a more stable vacuum, this "bubble" (also called "bounce") would spread.

A false vacuum exists at a local minimum of energy and is therefore not completely stable, in contrast to a true vacuum, which exists at a global minimum and is stable.

🔗 Mathematics 🔗 Physics

Stochastic resonance (SR) is a phenomenon where a signal that is normally too weak to be detected by a sensor, can be boosted by adding white noise to the signal, which contains a wide spectrum of frequencies. The frequencies in the white noise corresponding to the original signal's frequencies will resonate with each other, amplifying the original signal while not amplifying the rest of the white noise (thereby increasing the signal-to-noise ratio which makes the original signal more prominent). Further, the added white noise can be enough to be detectable by the sensor, which can then filter it out to effectively detect the original, previously undetectable signal.

This phenomenon of boosting undetectable signals by resonating with added white noise extends to many other systems, whether electromagnetic, physical or biological, and is an area of research.

🔗 Biography 🔗 Russia 🔗 Statistics 🔗 Biography/science and academia 🔗 Russia/science and education in Russia

Alexey Yakovlevich Chervonenkis (Russian: Алексей Яковлевич Червоненкис; 7 September 1938 – 22 September 2014) was a Soviet and Russian mathematician, and, with Vladimir Vapnik, was one of the main developers of the Vapnik–Chervonenkis theory, also known as the "fundamental theory of learning" an important part of computational learning theory. Chervonenkis held joint appointments with the Russian Academy of Sciences and Royal Holloway, University of London.

Alexey Chervonenkis got lost in Losiny Ostrov National Park on 22 September 2014, and later during a search operation was found dead near Mytishchi, a suburb of Moscow. He had died of hypothermia.

🔗 Computing 🔗 Photography 🔗 Computer graphics

Design rule for Camera File system (DCF) is a JEITA specification (number CP-3461) which defines a file system for digital cameras, including the directory structure, file naming method, character set, file format, and metadata format. It is currently the de facto industry standard for digital still cameras. The file format of DCF conforms to the Exif specification, but the DCF specification also allows use of any other file formats.

The latest version of the standard is 2.0 (2010 edition).

🔗 United States 🔗 United States/North Carolina 🔗 Aviation 🔗 Military history 🔗 Disaster management 🔗 Military history/Military aviation 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 United States/Military history - U.S. military history 🔗 Aviation/Aviation accident 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry

The 1961 Goldsboro B-52 crash was an accident that occurred near Goldsboro, North Carolina, on 23 January 1961. A Boeing B-52 Stratofortress carrying two 3–4-megaton Mark 39 nuclear bombs broke up in mid-air, dropping its nuclear payload in the process. The pilot in command, Walter Scott Tulloch, ordered the crew to eject at 9,000 feet (2,700 m). Five crewmen successfully ejected or bailed out of the aircraft and landed safely, another ejected, but did not survive the landing, and two died in the crash. Information declassified in 2013 showed that one of the bombs came very close to detonating.