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🔗 Africa 🔗 Africa/Botswana

The Okavango Delta (or Okavango Grassland) (formerly spelled "Okovango" or "Okovanggo") in Botswana is a swampy inland delta formed where the Okavango River reaches a tectonic trough in the central part of the endorheic basin of the Kalahari. All the water reaching the delta is ultimately evaporated and transpired and does not flow into any sea or ocean. Each year, about 11 cubic kilometres (2.6 cu mi) of water spread over the 6,000–15,000 km² (2,300–5,800 sq mi) area. Some flood waters drain into Lake Ngami. The area was once part of Lake Makgadikgadi, an ancient lake that had mostly dried up by the early Holocene.

The Moremi Game Reserve, a National Park, is on the eastern side of the Delta. The Delta was named as one of the Seven Natural Wonders of Africa, which were officially declared on 11 February 2013 in Arusha, Tanzania. On 22 June 2014, the Okavango Delta became the 1000th site to be officially inscribed on the UNESCO World Heritage List.

🔗 Biography 🔗 Biography/science and academia 🔗 Ireland

Percy Edwin Ludgate (2 August 1883 – 16 October 1922) was an Irish amateur scientist who designed the second analytical engine (general-purpose Turing-complete computer) in history.

🔗 Physics

In quantum mechanics, the Kochen–Specker (KS) theorem, also known as the Bell–Kochen–Specker theorem, is a "no-go" theorem proved by John S. Bell in 1966 and by Simon B. Kochen and Ernst Specker in 1967. It places certain constraints on the permissible types of hidden-variable theories, which try to explain the predictions of quantum mechanics in a context-independent way. The version of the theorem proved by Kochen and Specker also gave an explicit example for this constraint in terms of a finite number of state vectors.

The theorem is a complement to Bell's theorem (to be distinguished from the (Bell–)Kochen–Specker theorem of this article). While Bell's theorem established nonlocality to be a feature of any hidden variable theory that recovers the predictions of quantum mechanics, the KS theorem established contextuality to be an inevitable feature of such theories.

The theorem proves that there is a contradiction between two basic assumptions of the hidden-variable theories intended to reproduce the results of quantum mechanics: that all hidden variables corresponding to quantum-mechanical observables have definite values at any given time, and that the values of those variables are intrinsic and independent of the device used to measure them. The contradiction is caused by the fact that quantum-mechanical observables need not be commutative. It turns out to be impossible to simultaneously embed all the commuting subalgebras of the algebra of these observables in one commutative algebra, assumed to represent the classical structure of the hidden-variables theory, if the Hilbert space dimension is at least three.

The Kochen–Specker theorem excludes hidden-variable theories that assume that elements of physical reality can all be consistently represented simultaneously by the quantum mechanical Hilbert space formalism disregarding the context of a particular framework (technically a projective decomposition of the identity operator) related to the experiment or analytical viewpoint under consideration. As succinctly worded by Isham and Butterfield, (under the assumption of a universal probabilistic sample space as in non-contextual hidden variable theories) the Kochen–Specker theorem "asserts the impossibility of assigning values to all physical quantities whilst, at the same time, preserving the functional relations between them".

🔗 Computing 🔗 Telecommunications 🔗 Computer Security 🔗 Computer Security/Computing

Phreaking is a slang term coined to describe the activity of a culture of people who study, experiment with, or explore telecommunication systems, such as equipment and systems connected to public telephone networks. The term phreak is a sensational spelling of the word freak with the ph- from phone, and may also refer to the use of various audio frequencies to manipulate a phone system. Phreak, phreaker, or phone phreak are names used for and by individuals who participate in phreaking.

The term first referred to groups who had reverse engineered the system of tones used to route long-distance calls. By re-creating these tones, phreaks could switch calls from the phone handset, allowing free calls to be made around the world. To ease the creation of these tones, electronic tone generators known as blue boxes became a staple of the phreaker community. This community included future Apple Inc. cofounders Steve Jobs and Steve Wozniak.

The blue box era came to an end with the ever-increasing use of computerized phone systems which allowed telecommunication companies to discontinue the use of in-band signaling for call routing purposes. Instead, dialing information was sent on a separate channel which was inaccessible to the telecom customer. By the 1980s, most of the public switched telephone network (PSTN) in the US and Western Europe had adopted the SS7 system which uses out-of-band signaling for call control (and which is still in use to this day). Phreaking has since become closely linked with computer hacking.

🔗 Biography 🔗 Physics 🔗 Biography/science and academia 🔗 Physics/Biographies 🔗 Sicily

Ettore Majorana (, Italian: [ˈɛttore majoˈraːna]; born on 5 August 1906 – likely dying in or after 1959) was an Italian theoretical physicist who worked on neutrino masses. On 25 March 1938, he disappeared under mysterious circumstances after purchasing a ticket to travel by ship from Naples to Palermo.

The Majorana equation and Majorana fermions are named after him. In 2006, the Majorana Prize was established in his memory.

🔗 Russia 🔗 Disaster management 🔗 Terrorism 🔗 Russia/politics and law of Russia 🔗 Russia/history of Russia

The Russian apartment bombings were a series of explosions that hit four apartment blocks in the Russian cities of Buynaksk, Moscow and Volgodonsk in September 1999, killing more than 300, injuring more than 1000, and spreading a wave of fear across the country. The bombings, together with the Invasion of Dagestan, triggered the Second Chechen War. Then-prime minister Vladimir Putin's handling of the crisis boosted his popularity greatly and helped him attain the presidency within a few months. Russian courts ruled that the attacks were orchestrated by Chechen-linked militants, while some scholars, journalists, and politicians have argued that Russian security services likely organized the bombings.

The blasts hit Buynaksk on 4 September and in Moscow on 9 and 13 September. On 13 September, Russian Duma speaker Gennadiy Seleznyov made an announcement in the Duma about receiving a report that another bombing had just happened in the city of Volgodonsk. A bombing did indeed happen in Volgodonsk, but only three days later, on 16 September. Chechen militants were blamed for the bombings, but denied responsibility, along with Chechen president Aslan Maskhadov.

A suspicious device resembling those used in the bombings was found and defused in an apartment block in the Russian city of Ryazan on 22 September. On 23 September, Vladimir Putin praised the vigilance of the inhabitants of Ryazan and ordered the air bombing of Grozny, which marked the beginning of the Second Chechen War. Three FSB agents who had planted the devices at Ryazan were arrested by the local police. On 24 September 1999, head of FSB Nikolay Patrushev announced that the incident in Ryazan had been an anti-terror drill and the device found there contained only sugar.

The official Russian investigation of the Buynaksk bombing was completed in 2000, while the investigation of Moscow and Volgodonsk bombings was completed in 2002. In 2000, seven people were convicted of perpetrating the Buinaksk attack. According to the court ruling on the Moscow and Volgodonsk bombings, which was announced in 2004, the attacks were organised and led by Achemez Gochiyaev, who remains at large. All bombings, the court ruled, were ordered by Islamist warlords Ibn Al-Khattab and Abu Omar al-Saif, who have been killed. Five other suspects have been killed and six have been convicted by Russian courts on terrorism-related charges.

Parliament member Yuri Shchekochikhin filed two motions for a parliamentary investigation of the events, but the motions were rejected by the Russian Duma in March 2000. An independent public commission to investigate the bombings was chaired by Duma deputy Sergei Kovalev. The commission was rendered ineffective because of government refusal to respond to its inquiries. Two key members of the Kovalev Commission, Sergei Yushenkov and Yuri Shchekochikhin, have since died in apparent assassinations. The Commission’s lawyer and investigator Mikhail Trepashkin was arrested and served four years in prison for revealing state secrets. Former FSB agent Alexander Litvinenko, who defected and blamed the FSB for the bombings, was poisoned and killed in London in 2006. A British inquiry later determined that Litvinenko's murder was "probably" carried out with the approval of Putin and Patrushev.

The 1999 attacks were officially attributed to Chechen terrorists. According to some historians and journalists, the bombings were coordinated by the Russian state security services to bring Putin into the presidency. Others disagree with such theories. Independent investigations have faced obstruction from Russian security services, raising further suspicions about their involvement in the attacks.

🔗 Philosophy 🔗 Philosophy/Epistemology

In philosophy and psychology, an alief is an automatic or habitual belief-like attitude, particularly one that is in tension with a person's explicit beliefs.

For example, a person standing on a transparent balcony may believe that they are safe, but alieve that they are in danger. A person watching a sad movie may believe that the characters are completely fictional, but their aliefs may lead them to cry nonetheless. A person who is hesitant to eat fudge that has been formed into the shape of feces, or who exhibits reluctance in drinking from a sterilized bedpan may believe that the substances are safe to eat and drink, but may alieve that they are not.

The term alief was introduced by Tamar Gendler, a professor of philosophy and cognitive science at Yale University, in a pair of influential articles published in 2008. Since the publication of these original articles, the notion of alief has been utilized by Gendler and others — including Paul Bloom and Daniel Dennett — to explain a range of psychological phenomena in addition to those listed above, including the pleasure of stories, the persistence of positive illusions, certain religious beliefs, and certain psychiatric disturbances, such as phobias and obsessive–compulsive disorder.

🔗 Computing 🔗 Computing/Software 🔗 Computing/Amiga 🔗 Project-independent assessment

Amiga Unix (informally known as Amix) is a discontinued full port of AT&T Unix System V Release 4 operating system developed by Commodore-Amiga, Inc. in 1990 for the Amiga computer family as an alternative to AmigaOS, which shipped by default. Bundled with the Amiga 3000UX, Commodore's Unix was one of the first ports of SVR4 to the 68k architecture. The Amiga A3000UX model even got the attention of Sun Microsystems, though ultimately nothing came of it.

Unlike Apple's A/UX, Amiga Unix contained no compatibility layer to allow AmigaOS applications to run under Unix. With few native applications available to take advantage of the Amiga's significant multimedia capabilities, it failed to find a niche in the quite-competitive Unix workstation market of the early 1990s. The A3000UX's price tag of $4,998 (equivalent to $9,382 in 2019) was also not very attractive compared to other Unix workstations at the time, such as the NeXTstation ($5,000 for a base system, with a full API and many times the number of applications available), the SGI Indigo (starting at $8,000), or the Personal DECstation 5000 Model 25 (starting at $5,000). Sun, HP, and IBM had similarly priced systems. The A3000UX's 68030 was noticeably underpowered compared to most of its RISC-based competitors.

Unlike typical commercial Unix distributions of the time, Amiga Unix included the source code to the vendor-specific enhancements and platform-dependent device drivers (essentially any part that wasn't owned by AT&T), allowing interested users to study or enhance those parts of the system. However this source code was subject to the same license terms as the binary part of the system – it was not free software. Amiga Unix also incorporated and depended upon many open source components, such as the GNU C Compiler and X Window System, and included their source code.

Like many other proprietary Unix variants with small market shares, Amiga Unix vanished into the mists of computer history when its vendor, Commodore, went out of business. Today, Unix-like operating systems such as Minix, NetBSD, and Linux are available for the Amiga platform.

🔗 Food and drink

Dishwasher salmon is an American fish dish made with the heat from a dishwasher, particularly from its drying phase.