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🔗 Computing 🔗 Computing/Computer hardware 🔗 Computing/Software 🔗 Java

Jazelle DBX (direct bytecode execution) is an extension that allows some ARM processors to execute Java bytecode in hardware as a third execution state alongside the existing ARM and Thumb modes. Jazelle functionality was specified in the ARMv5TEJ architecture and the first processor with Jazelle technology was the ARM926EJ-S. Jazelle is denoted by a "J" appended to the CPU name, except for post-v5 cores where it is required (albeit only in trivial form) for architecture conformance.

Jazelle RCT (Runtime Compilation Target) is a different technology based on ThumbEE mode; it supports ahead-of-time (AOT) and just-in-time (JIT) compilation with Java and other execution environments.

The most prominent use of Jazelle DBX is by manufacturers of mobile phones to increase the execution speed of Java ME games and applications. A Jazelle-aware Java virtual machine (JVM) will attempt to run Java bytecode in hardware, while returning to the software for more complicated, or lesser-used bytecode operations. ARM claims that approximately 95% of bytecode in typical program usage ends up being directly processed in the hardware.

The published specifications are very incomplete, being only sufficient for writing operating system code that can support a JVM that uses Jazelle. The declared intent is that only the JVM software needs to (or is allowed to) depend on the hardware interface details. This tight binding facilitates the hardware and JVM evolving together without affecting other software. In effect, this gives ARM Holdings considerable control over which JVMs are able to exploit Jazelle. It also prevents open source JVMs from using Jazelle. These issues do not apply to the ARMv7 ThumbEE environment, the nominal successor to Jazelle DBX.

🔗 Trains 🔗 Trains/Monorail

The Wuppertaler Schwebebahn (Wuppertal Suspension Railway) is a suspension railway in Wuppertal, Germany.

Its full name is Anlage einer elektrischen Hochbahn (Schwebebahn), System Eugen Langen. ("Electric Elevated Railway (Suspension Railway) Installation, Eugen Langen System") It is the oldest electric elevated railway with hanging cars in the world and is a unique system.

Designed by Eugen Langen to sell to the city of Berlin, the installation with elevated stations was built in Barmen, Elberfeld and Vohwinkel between 1897 and 1903; the first track opened in 1901. The Schwebebahn is still in use today as a normal means of local public transport, moving 25 million passengers annually (2008).

The Schwebebahn runs along a route of 13.3 kilometres (8.3 mi), at a height of about 12 metres (39 ft) above the River Wupper between Oberbarmen and Sonnborner Straße (10 kilometres or 6.2 miles) and about 8 metres (26 ft) above the valley road between Sonnborner Straße and Vohwinkel (3.3 kilometres or 2.1 miles). At one point the railway crosses the A46 motorway. The entire trip takes about 30 minutes. The Schwebebahn operates within the VRR transport association and accepts tickets issued by the VRR companies.

Due to an accident in November 2018, the Schwebebahn was closed down for nearly nine months. It re-opened on 1 August 2019.

🔗 Internet 🔗 Internet culture 🔗 Philosophy 🔗 Futures studies

Roko's basilisk is a thought experiment which states that an otherwise benevolent artificial superintelligence (AI) in the future would be incentivized to create a virtual reality simulation to torture anyone who knew of its potential existence but did not directly contribute to its advancement or development. It originated in a 2010 post at discussion board LessWrong, a technical forum focused on analytical rational enquiry. The thought experiment's name derives from the poster of the article (Roko) and the basilisk, a mythical creature capable of destroying enemies with its stare.

While the theory was initially dismissed as nothing but conjecture or speculation by many LessWrong users, LessWrong co-founder Eliezer Yudkowsky reported users who described symptoms such as nightmares and mental breakdowns upon reading the theory, due to its stipulation that knowing about the theory and its basilisk made one vulnerable to the basilisk itself. This led to discussion of the basilisk on the site to be banned for five years. However, these reports were later dismissed as being exaggerations or inconsequential, and the theory itself was dismissed as nonsense, including by Yudkowsky himself. Even after the post's discreditation, it is still used as an example of principles such as Bayesian probability and implicit religion. It is also regarded as a modern version of Pascal's wager. In the field of artificial intelligence, Roko's basilisk has become notable as an example that raises the question of how to create an AI which is simultaneously moral and intelligent.

🔗 Germany 🔗 Astronomy 🔗 Archaeology 🔗 Visual arts

The Nebra sky disk is a bronze disk of around 30 centimeters (11 ³⁄₄ in) diameter and a weight of 2.2 kilograms (4.9 lb), having a blue-green patina and inlaid with gold symbols. These symbols are interpreted generally as the Sun or full moon, a lunar crescent, and stars (including a cluster of seven interpreted as the Pleiades). Two golden arcs along the sides, interpreted to mark the angle between the solstices, were added later. A final addition was another arc at the bottom surrounded with multiple strokes (of uncertain meaning, variously interpreted as a Solar Barge with numerous oars, the Milky Way, or a rainbow).

The disk is attributed to a site in present-day Germany near Nebra, Saxony-Anhalt, and dated by Archaeological association to c. 1600 BC. Researchers suggest the disk is an artifact of the Bronze Age Unetice culture.

The style in which the disk is executed was unlike any artistic style then known from the period, with the result that the object was initially suspected of being a forgery, but is now widely accepted as authentic.

The Nebra sky disk features the oldest concrete depiction of the cosmos yet known from anywhere in the world. In June 2013 it was included in the UNESCO Memory of the World Register and termed "one of the most important archaeological finds of the twentieth century."

🔗 Mathematics 🔗 Books 🔗 Systems

How to Solve It (1945) is a small volume by mathematician George Pólya describing methods of problem solving.

🔗 France 🔗 Military history 🔗 British Empire 🔗 Military history/French military history 🔗 Military history/Cold War 🔗 Colonialism 🔗 Egypt 🔗 Israel 🔗 Palestine 🔗 Military history/Middle Eastern military history 🔗 Military history/European military history 🔗 Military history/British military history

The Suez Crisis or the Second Arab–Israeli War, also referred to as the Tripartite Aggression in the Arab world and as the Sinai War in Israel, was a British–French–Israeli invasion of Egypt in 1956. Israel invaded on 29 October, having done so with the primary objective of re-opening the Straits of Tiran and the Gulf of Aqaba as the recent tightening of the eight-year-long Egyptian blockade further prevented Israeli passage. After issuing a joint ultimatum for a ceasefire, the United Kingdom and France joined the Israelis on 5 November, seeking to depose Egyptian president Gamal Abdel Nasser and regain control of the Suez Canal, which Nasser had earlier nationalised by transferring administrative control from the foreign-owned Suez Canal Company to Egypt's new government-owned Suez Canal Authority. Shortly after the invasion began, the three countries came under heavy political pressure from both the United States and the Soviet Union, as well as from the United Nations, eventually prompting their withdrawal from Egypt. Israel's four-month-long occupation of the Egyptian-occupied Gaza Strip and Egypt's Sinai Peninsula enabled it to attain freedom of navigation through the Straits of Tiran, but the Suez Canal itself was closed from October 1956 to March 1957. The Suez Crisis led to international humiliation for the British and the French in the wake of the Cold War, which established the Americans and the Soviets as the world's superpowers. It also strengthened Nasser's standing.

Before they were defeated, Egyptian troops had blocked all ship traffic by sinking 40 ships in the Suez Canal. It later became clear that Israel, the United Kingdom, and France had conspired to invade Egypt. Though the three allies had attained a number of their military objectives, the Suez Canal itself was useless. American president Dwight D. Eisenhower had issued a strong warning to the British if they were to invade Egypt; he threatened serious damage to the British financial system by selling the American government's bonds of pound sterling. Historians have concluded that the Suez Crisis "signified the end of Great Britain's role as one of the world's major powers" vis-à-vis the United States and the Soviet Union.

As a result of the conflict, the United Nations established the United Nations Emergency Force to police and patrol the Egypt–Israel border, while British prime minister Anthony Eden resigned from his position. For his diplomatic efforts in resolving the conflict through United Nations initiatives, Canadian external affairs minister Lester B. Pearson received a Nobel Peace Prize. Analysts have argued that the Suez Crisis may have emboldened the Soviet Union, prompting the Soviet invasion of Hungary.

🔗 Spaceflight 🔗 Military history 🔗 Military history/Military aviation 🔗 Military history/Maritime warfare 🔗 Moon 🔗 Smithsonian Institution-related 🔗 National Archives

Apollo 11 was the spaceflight that first landed humans on the Moon. Commander Neil Armstrong and lunar module pilot Buzz Aldrin formed the American crew that landed the Apollo Lunar Module Eagle on July 20, 1969, at 20:17 UTC. Armstrong became the first person to step onto the lunar surface six hours and 39 minutes later on July 21 at 02:56 UTC; Aldrin joined him 19 minutes later. They spent about two and a quarter hours together outside the spacecraft, and they collected 47.5 pounds (21.5 kg) of lunar material to bring back to Earth. Command module pilot Michael Collins flew the Command Module Columbia alone in lunar orbit while they were on the Moon's surface. Armstrong and Aldrin spent 21 hours, 36 minutes on the lunar surface at a site they named Tranquility Base before lifting off to rejoin Columbia in lunar orbit.

Apollo 11 was launched by a Saturn V rocket from Kennedy Space Center on Merritt Island, Florida, on July 16 at 13:32 UTC, and it was the fifth crewed mission of NASA's Apollo program. The Apollo spacecraft had three parts: a command module (CM) with a cabin for the three astronauts, the only part that returned to Earth; a service module (SM), which supported the command module with propulsion, electrical power, oxygen, and water; and a lunar module (LM) that had two stages—a descent stage for landing on the Moon and an ascent stage to place the astronauts back into lunar orbit.

After being sent to the Moon by the Saturn V's third stage, the astronauts separated the spacecraft from it and traveled for three days until they entered lunar orbit. Armstrong and Aldrin then moved into Eagle and landed in the Sea of Tranquility on July 20. The astronauts used Eagle's ascent stage to lift off from the lunar surface and rejoin Collins in the command module. They jettisoned Eagle before they performed the maneuvers that propelled Columbia out of the last of its 30 lunar orbits onto a trajectory back to Earth. They returned to Earth and splashed down in the Pacific Ocean on July 24 after more than eight days in space.

Armstrong's first step onto the lunar surface was broadcast on live TV to a worldwide audience. He described the event as "one small step for [a] man, one giant leap for mankind." Apollo 11 effectively ended the Space Race and fulfilled a national goal proposed in 1961 by President John F. Kennedy: "before this decade is out, of landing a man on the Moon and returning him safely to the Earth."

🔗 Medicine 🔗 Psychology 🔗 Sociology 🔗 Science 🔗 Academic Journals

The replication crisis (or replicability crisis or reproducibility crisis) is, as of 2020, an ongoing methodological crisis in which it has been found that many scientific studies are difficult or impossible to replicate or reproduce. The replication crisis affects the social sciences and medicine most severely. The crisis has long-standing roots; the phrase was coined in the early 2010s as part of a growing awareness of the problem. The replication crisis represents an important body of research in the field of metascience.

Because the reproducibility of experimental results is an essential part of the scientific method, the inability to replicate the studies of others has potentially grave consequences for many fields of science in which significant theories are grounded on unreproducible experimental work. The replication crisis has been particularly widely discussed in the field of psychology and in medicine, where a number of efforts have been made to re-investigate classic results, to determine both the reliability of the results, and, if found to be unreliable, the reasons for the failure of replication.

🔗 Mathematics

The art gallery problem or museum problem is a well-studied visibility problem in computational geometry. It originates from a real-world problem of guarding an art gallery with the minimum number of guards who together can observe the whole gallery. In the geometric version of the problem, the layout of the art gallery is represented by a simple polygon and each guard is represented by a point in the polygon. A set ${\displaystyle S}$ of points is said to guard a polygon if, for every point ${\displaystyle p}$ in the polygon, there is some ${\displaystyle q\in S}$ such that the line segment between ${\displaystyle p}$ and ${\displaystyle q}$ does not leave the polygon.

🔗 Computing 🔗 Systems 🔗 Computing/Software 🔗 Computing/Computer science 🔗 Systems/Systems engineering

Conway's law is an adage stating that organizations design systems that mirror their own communication structure. It is named after computer programmer Melvin Conway, who introduced the idea in 1967. His original wording was:

Any organization that designs a system (defined broadly) will produce a design whose structure is a copy of the organization's communication structure.

The law is based on the reasoning that in order for a software module to function, multiple authors must communicate frequently with each other. Therefore, the software interface structure of a system will reflect the social boundaries of the organization(s) that produced it, across which communication is more difficult. Conway's law was intended as a valid sociological observation, although sometimes it's used in a humorous context. It was dubbed Conway's law by participants at the 1968 National Symposium on Modular Programming.

In colloquial terms, it means software or automated systems end up "shaped like" the organizational structure they are designed in or designed for. Some interpretations of the law say this organizational pattern mirroring is a helpful feature of such systems, while other interpretations say it's merely a result of human nature or organizational bias.