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🔗 Philosophy 🔗 Philosophy/Logic 🔗 Philosophy/Epistemology

The theory of belief functions, also referred to as evidence theory or Dempster–Shafer theory (DST), is a general framework for reasoning with uncertainty, with understood connections to other frameworks such as probability, possibility and imprecise probability theories. First introduced by Arthur P. Dempster in the context of statistical inference, the theory was later developed by Glenn Shafer into a general framework for modeling epistemic uncertainty—a mathematical theory of evidence. The theory allows one to combine evidence from different sources and arrive at a degree of belief (represented by a mathematical object called belief function) that takes into account all the available evidence.

In a narrow sense, the term Dempster–Shafer theory refers to the original conception of the theory by Dempster and Shafer. However, it is more common to use the term in the wider sense of the same general approach, as adapted to specific kinds of situations. In particular, many authors have proposed different rules for combining evidence, often with a view to handling conflicts in evidence better. The early contributions have also been the starting points of many important developments, including the transferable belief model and the theory of hints.

🔗 Environment 🔗 Disaster management 🔗 Agriculture 🔗 Norway 🔗 Plants 🔗 Genetics

The Svalbard Global Seed Vault (Norwegian: Svalbard globale frøhvelv) is a secure seed bank on the Norwegian island of Spitsbergen in the remote Arctic Svalbard archipelago. Conservationist Cary Fowler, in association with the Consultative Group on International Agricultural Research (CGIAR), started the vault to preserve a wide variety of plant seeds that are duplicate samples, or "spare" copies, of seeds held in gene banks worldwide. The seed vault is an attempt to ensure against the loss of seeds in other genebanks during large-scale regional or global crises. The seed vault is managed under terms spelled out in a tripartite agreement among the Norwegian government, the Crop Trust, and the Nordic Genetic Resource Center (NordGen).

The Norwegian government entirely funded the vault's approximately 45 million kr (US$8.8 million in 2008) construction. Storing seeds in the vault is free to end users; Norway and the Crop Trust pay for operational costs. Primary funding for the Trust comes from organisations such as the Bill & Melinda Gates Foundation and from various governments worldwide.

🔗 Computer science

Boids is an artificial life program, developed by Craig Reynolds in 1986, which simulates the flocking behaviour of birds. His paper on this topic was published in 1987 in the proceedings of the ACM SIGGRAPH conference. The name "boid" corresponds to a shortened version of "bird-oid object", which refers to a bird-like object. Incidentally, "boid" is also a New York Metropolitan dialect pronunciation for "bird".

As with most artificial life simulations, Boids is an example of emergent behavior; that is, the complexity of Boids arises from the interaction of individual agents (the boids, in this case) adhering to a set of simple rules. The rules applied in the simplest Boids world are as follows:

• separation: steer to avoid crowding local flockmates
• alignment: steer towards the average heading of local flockmates
• cohesion: steer to move towards the average position (center of mass) of local flockmates

More complex rules can be added, such as obstacle avoidance and goal seeking.

The basic model has been extended in several different ways since Reynolds proposed it. For instance, Delgado-Mata et al. extended the basic model to incorporate the effects of fear. Olfaction was used to transmit emotion between animals, through pheromones modelled as particles in a free expansion gas. Hartman and Benes introduced a complementary force to the alignment that they call the change of leadership. This steer defines the chance of the boid to become a leader and try to escape.

The movement of Boids can be characterized as either chaotic (splitting groups and wild behaviour) or orderly. Unexpected behaviours, such as splitting flocks and reuniting after avoiding obstacles, can be considered emergent.

The boids framework is often used in computer graphics, providing realistic-looking representations of flocks of birds and other creatures, such as schools of fish or herds of animals. It was for instance used in the 1998 video game Half-Life for the flying bird-like creatures seen at the end of the game on Xen, named "boid" in the game files.

The Boids model can be used for direct control and stabilization of teams of simple Unmanned Ground Vehicles (UGV) or Micro Aerial Vehicles (MAV) in swarm robotics. For stabilization of heterogeneous UAV-UGV teams, the model was adapted for using onboard relative localization by Saska et al.

At the time of proposal, Reynolds' approach represented a giant step forward compared to the traditional techniques used in computer animation for motion pictures. The first animation created with the model was Stanley and Stella in: Breaking the Ice (1987), followed by a feature film debut in Tim Burton's film Batman Returns (1992) with computer generated bat swarms and armies of penguins marching through the streets of Gotham City.

The boids model has been used for other interesting applications. It has been applied to automatically program Internet multi-channel radio stations. It has also been used for visualizing information and for optimization tasks.

🔗 Internet

Do Not Track (DNT) was a proposed HTTP header field, designed to allow internet users to opt-out of tracking by websites—which includes the collection of data regarding a user's activity across multiple distinct contexts, and the retention, use, or sharing of data derived from that activity outside the context in which it occurred.

The Do Not Track header was originally proposed in 2009 by researchers Christopher Soghoian, Sid Stamm, and Dan Kaminsky. Efforts to standardize Do Not Track by the W3C in the Tracking Preference Expression (DNT) Working Group did not make it past the Candidate Recommendation stage and ended in September 2018 due to insufficient deployment and support.Mozilla Firefox became the first browser to implement the feature, while Internet Explorer, Apple's Safari, Opera and Google Chrome all later added support.

DNT is not widely adopted by the industry, with companies citing the lack of legal mandates for its use, as well as unclear standards and guidelines for how websites are to interpret the header. Thus, it is not guaranteed that enabling DNT will actually have any effect at all. The W3C disbanded its DNT working group in January 2019, citing insufficient support and adoption. Apple discontinued support for DNT the following month.

🔗 Typography

The Paige Compositor was an invention developed by James W. Paige (1842–1917) between 1872 and 1888. It was designed to replace the human typesetter of a lead type-composed printing form with a mechanical arm. In the early 1890s, a group of inventors signed a contract with Towner K. Webster in Chicago to produce 3000 compositors. However, the machine was not nearly as precise as it should have been and never turned a profit because of its complexity and continual need for adjustment based upon trial and error. As a result, it was the Linotype typesetting machine, which composed in a hot metal typesetting process, that became the new popular typesetting machine.

The Paige typesetting machine is notable for substantial investment that the prominent writer Mark Twain made into the failed endeavor: $300,000 ($6,000,000 today). Twain, a former printer, invested not only the bulk of his book profits but also a large portion of the inheritance of Olivia Clemens, his wife. Many point to his over-investment in the Paige typesetting machine and other inventions as the cause of not only his family's financial decline but also the decline of his wit and humor.

Webster Manufacturing made fewer than six machines costing $15,000 apiece, over three times as much as the initial production estimates. One was donated by Cornell University for a scrap metal drive during World War II. The only surviving machine is displayed at the Mark Twain House in Hartford, Connecticut.

🔗 Chemicals 🔗 Occupational Safety and Health 🔗 Food and drink 🔗 Rocks and minerals 🔗 Chemicals/Chemicals worklist

Borax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important boron compound, a mineral, and a salt of boric acid. Powdered borax is white, consisting of soft colorless crystals that dissolve in water. A number of closely related minerals or chemical compounds that differ in their crystal water content are referred to as borax, and the word is usually used to refer to the octahydrate. Commercially sold borax is partially dehydrated.

Borax is a component of many detergents, cosmetics, and enamel glazes. It is used to make buffer solutions in biochemistry, as a fire retardant, as an anti-fungal compound, in the manufacture of fiberglass, as a flux in metallurgy, neutron-capture shields for radioactive sources, a texturing agent in cooking, as a cross-linking agent in Slime, as an alkali in photographic developers, as a precursor for other boron compounds, and along with its inverse, boric acid, is useful as an insecticide.

In artisanal gold mining, borax is sometimes used as part of a process (as a flux) meant to eliminate the need for toxic mercury in the gold extraction process, although it cannot directly replace mercury. Borax was reportedly used by gold miners in parts of the Philippines in the 1900s.

Borax was first discovered in dry lake beds in Tibet and was imported via the Silk Road to the Arabian Peninsula in the 8th century AD. Borax first came into common use in the late 19th century when Francis Marion Smith's Pacific Coast Borax Company began to market and popularize a large variety of applications under the 20 Mule Team Borax trademark, named for the method by which borax was originally hauled out of the California and Nevada deserts.

🔗 Politics 🔗 Anti-war 🔗 Globalization

Global Peace Index (GPI) measures the relative position of nations' and regions' peacefulness. The GPI ranks 172 independent states and territories (99.7 percent of the world's population) according to their levels of peacefulness. In the past decade, the GPI has presented trends of increased global violence and less peacefulness. It also increases the world peace program in the world.

The GPI is a report produced by the Institute for Economics & Peace (IEP) and developed in consultation with an international panel of peace experts from peace institutes and think tanks with data collected and collated by the Economist Intelligence Unit. The Index was first launched in May 2009, with subsequent reports being released annually. In 2015 it ranked 165 countries, up from 121 in 2007. The study was conceived by Australian technology entrepreneur Steve Killelea, and is endorsed by individuals such as former UN Secretary-General Kofi Annan, the Dalai Lama, archbishop Desmond Tutu, former President of Finland and 2008 Nobel Peace Prize laureate Martti Ahtisaari, Nobel laureate Muhammad Yunus, economist Jeffrey Sachs, former president of Ireland Mary Robinson, former Deputy Secretary-General of the United Nations Jan Eliasson and former United States president Jimmy Carter. The updated index is released each year at events in London, Washington, DC; and at the United Nations Secretariat in New York.

The 2019 GPI indicates Iceland, New Zealand, Portugal, Austria and Denmark to be the most peaceful countries and Somalia, Afghanistan, Syria, South Sudan, Yemen, and Iraq to be the least peaceful. Long-term findings of the 2017 GPI include a less peaceful world over the past decade, a 2.14 per cent deterioration in the global level of peace in the past decade, growing inequality in peace between the most and least peaceful countries, a long-term reduction in the GPI Militarization domain, and a widening impact of terrorism, with historically high numbers of people killed in terrorist incidents over the past 10 years.

🔗 Physics 🔗 Astronomy

A helium flash is a very brief thermal runaway nuclear fusion of large quantities of helium into carbon through the triple-alpha process in the core of low mass stars (between 0.8 solar masses (M_☉) and 2.0 M_☉) during their red giant phase. The Sun is predicted to experience a flash 1.2 billion years after it leaves the main sequence. A much rarer runaway helium fusion process can also occur on the surface of accreting white dwarf stars.

Low-mass stars do not produce enough gravitational pressure to initiate normal helium fusion. As the hydrogen in the core is exhausted, some of the helium left behind is instead compacted into degenerate matter, supported against gravitational collapse by quantum mechanical pressure rather than thermal pressure. Subsequent hydrogen shell fusion further increases the mass of the core until it reaches temperature of approximately 100 million kelvin, which is hot enough to initiate helium fusion (or "helium burning") in the core.

However, a fundamental quality of degenerate matter is that increases in temperature do not produce an increase in the pressure of the matter until the thermal pressure becomes so very high that it exceeds degeneracy pressure. In main sequence stars, thermal expansion regulates the core temperature, but in degenerate cores, this does not occur. Helium fusion increases the temperature, which increases the fusion rate, which further increases the temperature in a runaway reaction which quickly spans the entire core. This produces a flash of very intense helium fusion that lasts only a few minutes, but during that time, produces energy at a rate comparable to the entire Milky Way galaxy.

In the case of normal low-mass stars, the vast energy release causes much of the core to come out of degeneracy, allowing it to thermally expand. This consumes most of the total energy released by the helium flash, and any left-over energy is absorbed into the star's upper layers. Thus the helium flash is mostly undetectable by observation, and is described solely by astrophysical models. After the core's expansion and cooling, the star's surface rapidly cools and contracts in as little as 10,000 years until it is roughly 2% of its former radius and luminosity. It is estimated that the electron-degenerate helium core weighs about 40% of the star mass and that 6% of the core is converted into carbon.

🔗 Computer science

In computer programming, the Schwartzian transform is a technique used to improve the efficiency of sorting a list of items. This idiom is appropriate for comparison-based sorting when the ordering is actually based on the ordering of a certain property (the key) of the elements, where computing that property is an intensive operation that should be performed a minimal number of times. The Schwartzian transform is notable in that it does not use named temporary arrays.

The Schwartzian transform is a version of a Lisp idiom known as decorate-sort-undecorate, which avoids recomputing the sort keys by temporarily associating them with the input items. This approach is similar to memoization, which avoids repeating the calculation of the key corresponding to a specific input value. By comparison, this idiom assures that each input item's key is calculated exactly once, which may still result in repeating some calculations if the input data contains duplicate items.

The idiom is named after Randal L. Schwartz, who first demonstrated it in Perl shortly after the release of Perl 5 in 1994. The term "Schwartzian transform" applied solely to Perl programming for a number of years, but it has later been adopted by some users of other languages, such as Python, to refer to similar idioms in those languages. However, the algorithm was already in use in other languages (under no specific name) before it was popularized among the Perl community in the form of that particular idiom by Schwartz. The term "Schwartzian transform" indicates a specific idiom, and not the algorithm in general.

For example, to sort the word list ("aaaa","a","aa") according to word length: first build the list (["aaaa",4],["a",1],["aa",2]), then sort it according to the numeric values getting (["a",1],["aa",2],["aaaa",4]), then strip off the numbers and you get ("a","aa","aaaa"). That was the algorithm in general, so it does not count as a transform. To make it a true Schwartzian transform, it would be done in Perl like this:

🔗 Architecture 🔗 London 🔗 England 🔗 United Kingdom 🔗 Citizendium Porting 🔗 Glass 🔗 Kent 🔗 Scouting/Girl Guiding and Girl Scouting 🔗 Scouting

The Crystal Palace was a cast-iron and plate-glass structure originally built in Hyde Park, London, to house the Great Exhibition of 1851. The exhibition took place from 1 May until 15 October 1851, and more than 14,000 exhibitors from around the world gathered in its 990,000 square feet (92,000 m²) exhibition space to display examples of technology developed in the Industrial Revolution. Designed by Joseph Paxton, the Great Exhibition building was 1,851 feet (564 m) long, with an interior height of 128 feet (39 m). It was three times the size of St Paul's Cathedral.

The introduction of the sheet glass method into Britain by Chance Brothers in 1832 made possible the production of large sheets of cheap but strong glass, and its use in the Crystal Palace created a structure with the greatest area of glass ever seen in a building. It astonished visitors with its clear walls and ceilings that did not require interior lights.

It has been suggested that the name of the building resulted from a piece penned by the playwright Douglas Jerrold, who in July 1850 wrote in the satirical magazine Punch about the forthcoming Great Exhibition, referring to a "palace of very crystal".

After the exhibition, the Palace was relocated to an area of South London known as Penge Common. It was rebuilt at the top of Penge Peak next to Sydenham Hill, an affluent suburb of large villas. It stood there from June 1854 until its destruction by fire in November 1936. The nearby residential area was renamed Crystal Palace after the landmark. This included the Crystal Palace Park that surrounds the site, home of the Crystal Palace National Sports Centre, which had previously been a football stadium that hosted the FA Cup Final between 1895 and 1914. Crystal Palace F.C. were founded at the site in 1905 and played at the Cup Final venue in their early years. The park still contains Benjamin Waterhouse Hawkins's Crystal Palace Dinosaurs which date back to 1854.