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🔗 Medicine

The Therac-25 was a computer-controlled radiation therapy machine produced by Atomic Energy of Canada Limited (AECL) in 1982 after the Therac-6 and Therac-20 units (the earlier units had been produced in partnership with CGR of France).

It was involved in at least six accidents between 1985 and 1987, in which patients were given massive overdoses of radiation. Because of concurrent programming errors, it sometimes gave its patients radiation doses that were hundreds of times greater than normal, resulting in death or serious injury. These accidents highlighted the dangers of software control of safety-critical systems, and they have become a standard case study in health informatics and software engineering. Additionally the overconfidence of the engineers and lack of proper due diligence to resolve reported software bugs are highlighted as an extreme case where the engineers' overconfidence in their initial work and failure to believe the end users' claims caused drastic repercussions.

🔗 Computing

Plankalkül (German pronunciation: [ˈplaːnkalkyːl]) is a programming language designed for engineering purposes by Konrad Zuse between 1942 and 1945. It was the first high-level programming language to be designed for a computer.

Kalkül is the German term for a formal system—as in Hilbert-Kalkül, the original name for the Hilbert-style deduction system—so Plankalkül refers to a formal system for planning.

🔗 Websites 🔗 Websites/Computing

Hacker News is a social news website focusing on computer science and entrepreneurship. It is run by Paul Graham's investment fund and startup incubator, Y Combinator. In general, content that can be submitted is defined as "anything that gratifies one's intellectual curiosity".

🔗 Military history 🔗 Military history/Military aviation 🔗 Military history/World War II 🔗 Military history/German military history 🔗 Military history/European military history 🔗 Military history/British military history

The Charlie Brown and Franz Stigler incident occurred on 20 December 1943, when, after a successful bomb run on Bremen, 2nd Lt Charles "Charlie" Brown's B-17 Flying Fortress (named "Ye Olde Pub") was severely damaged by German fighters. Luftwaffe pilot Franz Stigler had the opportunity to shoot down the crippled bomber but did not do so. After an extensive search by Brown, the two pilots met each other 50 years later and developed a friendship that lasted until Stigler's death in March 2008.

🔗 California 🔗 California/San Francisco Bay Area 🔗 Computing 🔗 Computing/Computer hardware

The traitorous eight was a group of eight employees who left Shockley Semiconductor Laboratory in 1957 to found Fairchild Semiconductor. William Shockley had in 1956 recruited a group of young PhD graduates with the goal to develop and produce new semiconductor devices. While Shockley had received a Nobel Prize in Physics and was an experienced researcher and teacher, his management of the group was authoritarian and unpopular. This was accentuated by Shockley's research focus not proving fruitful. After the demand for Shockley to be replaced was rebuffed, the eight left to form their own company.

Shockley described their leaving as a "betrayal". The eight who left Shockley Semiconductor were Julius Blank, Victor Grinich, Jean Hoerni, Eugene Kleiner, Jay Last, Gordon Moore, Robert Noyce, and Sheldon Roberts. In August 1957, they reached an agreement with Sherman Fairchild, and on September 18, 1957, they formed Fairchild Semiconductor. The newly founded Fairchild Semiconductor soon grew into a leader of the semiconductor industry. In 1960, it became an incubator of Silicon Valley and was directly or indirectly involved in the creation of dozens of corporations, including Intel and AMD. These many spin-off companies came to be known as "Fairchildren".

🔗 Skepticism 🔗 History of Science 🔗 Sociology

The Sokal affair, also called the Sokal hoax, was a scholarly publishing sting perpetrated by Alan Sokal, a physics professor at New York University and University College London. In 1996, Sokal submitted an article to Social Text, an academic journal of postmodern cultural studies. The submission was an experiment to test the journal's intellectual rigor and, specifically, to investigate whether "a leading North American journal of cultural studies—whose editorial collective includes such luminaries as Fredric Jameson and Andrew Ross—[would] publish an article liberally salted with nonsense if (a) it sounded good and (b) it flattered the editors' ideological preconceptions".

The article, "Transgressing the Boundaries: Towards a Transformative Hermeneutics of Quantum Gravity", was published in the Social Text spring/summer 1996 "Science Wars" issue. It proposed that quantum gravity is a social and linguistic construct. At that time, the journal did not practice academic peer review and it did not submit the article for outside expert review by a physicist. Three weeks after its publication in May 1996, Sokal revealed in Lingua Franca that the article was a hoax.

The hoax sparked a debate about the scholarly merit of commentary on the physical sciences by those in the humanities; the influence of postmodern philosophy on social disciplines in general; academic ethics, including whether Sokal was wrong to deceive the editors and readers of Social Text; and whether Social Text had exercised appropriate intellectual rigor.

🔗 Physics

Landauer's principle is a physical principle pertaining to the lower theoretical limit of energy consumption of computation. It holds that "any logically irreversible manipulation of information, such as the erasure of a bit or the merging of two computation paths, must be accompanied by a corresponding entropy increase in non-information-bearing degrees of freedom of the information-processing apparatus or its environment".

Another way of phrasing Landauer's principle is that if an observer loses information about a physical system, the observer loses the ability to extract work from that system.

A so-called logically-reversible computation, in which no information is erased, may in principle be carried out without releasing any heat. This has led to considerable interest in the study of reversible computing. Indeed, without reversible computing, increases in the number of computations-per-joule-of-energy-dissipated must come to a halt by about 2050: because the limit implied by Landauer's principle will be reached by then, according to Koomey's law.

At 20 °C (room temperature, or 293.15 K), the Landauer limit represents an energy of approximately 0.0175 eV, or 2.805 zJ. Theoretically, room‑temperature computer memory operating at the Landauer limit could be changed at a rate of one billion bits per second (1Gbps) with energy being converted to heat in the memory media at the rate of only 2.805 trillionths of a watt (that is, at a rate of only 2.805 pJ/s). Modern computers use millions of times as much energy per second.

🔗 Computer science

The inner-platform effect is the tendency of software architects to create a system so customizable as to become a replica, and often a poor replica, of the software development platform they are using. This is generally inefficient and such systems are often considered to be examples of an anti-pattern.

🔗 Biography 🔗 Computer science 🔗 Biography/science and academia 🔗 Denmark

Peter Naur (25 October 1928 – 3 January 2016) was a Danish computer science pioneer and Turing award winner. His last name is the "N" in the BNF notation (Backus–Naur form), used in the description of the syntax for most programming languages. He contributed to the creation of the ALGOL 60 programming language.

🔗 Aviation 🔗 Aviation/rotorcraft

Jesus nut is a slang term for the main rotor retaining nut or mast nut, which holds the main rotor to the mast of some helicopters. The related slang term Jesus pin refers to the lock pin used to secure the retaining nut. More generally, Jesus nut (or Jesus pin) has been used to refer to any component that is a single point of failure which results in catastrophic consequences.