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🔗 Computing

A quine is a computer program which takes no input and produces a copy of its own source code as its only output. The standard terms for these programs in the computability theory and computer science literature are "self-replicating programs", "self-reproducing programs", and "self-copying programs".

A quine is a fixed point of an execution environment, when the execution environment is viewed as a function transforming programs into their outputs. Quines are possible in any Turing complete programming language, as a direct consequence of Kleene's recursion theorem. For amusement, programmers sometimes attempt to develop the shortest possible quine in any given programming language.

The name "quine" was coined by Douglas Hofstadter, in his popular science book Gödel, Escher, Bach, in honor of philosopher Willard Van Orman Quine (1908–2000), who made an extensive study of indirect self-reference, and in particular for the following paradox-producing expression, known as Quine's paradox:

"Yields falsehood when preceded by its quotation" yields falsehood when preceded by its quotation.

🔗 Highways 🔗 Road transport 🔗 Transport in Scotland 🔗 Highways/United Kingdom Roads 🔗 UK geography

The Great Britain road numbering scheme is a numbering scheme used to classify and identify all roads in Great Britain. Each road is given a single letter, which represents the road's category, and a subsequent number, of 1 to 4 digits. Introduced to arrange funding allocations, the numbers soon became used on maps and as a method of navigation. Two sub-schemes exist: one for motorways, and another for non-motorway roads. While some major roads form part of the International E-road network, no E-routes are signposted in Great Britain, or the rest of the UK.

The scheme applies only to Great Britain (England, Scotland and Wales); a similar system is used in Northern Ireland, as well as outside the UK in the Isle of Man, Jersey and British overseas territories. These other numbering schemes use similar conventions.

🔗 Classical Greece and Rome

The wine-dark sea is a traditional English translation of οἶνοψ πόντος (oînops póntos, IPA: /ôi̯.nops pón.tos/), from οἶνος (oînos, “wine”) + ὄψ (óps, “eye; face”). It is an epithet in Homer of uncertain meaning: a literal translation is "wine-face sea" (wine-faced, wine-eyed). It is attested five times in the Iliad and twelve times in the Odyssey, often to describe rough, stormy sea.

The only other use of oînops in the works of Homer is for oxen (once in both his epic poems), where it seems to describe a reddish color, which has given rise to various speculations about what it could mean about either the state of Aegean Sea during antiquity or the color perception of Ancient Greeks.

🔗 Internet 🔗 Computing 🔗 Computing/Computer Security 🔗 Computing/Websites 🔗 Computing/Networking

Domain fronting is a technique for Internet censorship circumvention that uses different domain names in different communication layers of an HTTPS connection to discreetly connect to a different target domain than is discernable to third parties monitoring the requests and connections.

Due to quirks in security certificates, the redirect systems of the content delivery networks (CDNs) used as 'domain fronts', and the protection provided by HTTPS, censors are typically unable to differentiate circumvention ("domain-fronted") traffic from overt non-fronted traffic for any given domain name. As such they are forced to either allow all traffic to the domain front—including circumvention traffic—or block the domain front entirely, which may result in expensive collateral damage and has been likened to "blocking the rest of the Internet".

Domain fronting does not conform to HTTP standards that require the SNI extension and HTTP Host header to contain the same domain. Many large cloud service providers, including Amazon, Microsoft, and Google, actively prohibit domain fronting, which has limited it as a censorship bypass technique. Pressure from censors in Russia and China is thought to have contributed to these prohibitions, but domain fronting can also be used maliciously.

A newer variant of domain fronting, domain hiding, passes an encrypted request for one resource (say, a website), concealed behind an unencrypted (plaintext) request for another resource whose DNS records are stored in the same cloud. It has much the same effect. Refraction networking is an application of the broader principle.

🔗 New York City 🔗 Engineering

The Citicorp Center engineering crisis was the discovery, in 1978, of a significant structural flaw in Citicorp Center, then a recently completed skyscraper in New York City, and the subsequent effort to quietly make repairs over the next few months. The building, now known as Citigroup Center, occupied an entire block and was to be the headquarters of Citibank. Its structure, designed by William LeMessurier, had several unusual design features, including a raised base supported by four offset stilts, and diagonal bracing which absorbed wind loads from upper stories.

In the original design, potential wind loads for the building were calculated incorrectly. The flaw was discovered by Diane Hartley, an undergraduate student at Princeton University who was writing a thesis on the building, and was communicated to the firm responsible for the structural design. LeMessurier was subsequently lauded for acknowledging his error and orchestrating a successful repair effort. Estimates at the time suggested that the building could be toppled by a 70-mile-per-hour (110 km/h) wind, with possibly many people killed as a result. The crisis was kept secret until 1995 and Hartley had no knowledge of the significance of her work until after that time.

🔗 Chemicals

Aluminium oxynitride (marketed under the name ALON by Surmet Corporation) is a transparent ceramic composed of aluminium, oxygen and nitrogen. ALON is optically transparent (≥ 80%) in the near-ultraviolet, visible, and midwave-infrared regions of the electromagnetic spectrum. It is four times as hard as fused silica glass, 85% as hard as sapphire, and nearly 115% as hard as magnesium aluminate spinel. Since it has a cubic spinel structure, it can be fabricated to transparent windows, plates, domes, rods, tubes, and other forms using conventional ceramic powder processing techniques.

ALON is the hardest polycrystalline transparent ceramic available commercially. Because of its relatively low weight, distinctive optical and mechanical properties, and resistance to oxidation or radiation, it shows promise for applications such as bulletproof, blast-resistant, and optoelectronic windows. ALON-based armor has been shown to stop multiple armor-piercing projectiles of up to .50 BMG.

ALON is commercially available in sizes as large as 18-by-35-inch (460 mm × 890 mm; 46 cm × 89 cm) monolithic windows.

🔗 United States 🔗 Biography 🔗 Computing 🔗 Women scientists 🔗 Biography/science and academia 🔗 Women's History 🔗 Chicago 🔗 Catholicism 🔗 United States/Iowa

Mary Kenneth Keller, B.V.M. (December 17, 1913 – January 10, 1985) was an American Roman Catholic religious sister, educator and pioneer in computer science. She and Irving C. Tang were the first two people to earn a doctorate in computer science in the United States.

🔗 Biography 🔗 Russia 🔗 Computing 🔗 Russia/technology and engineering in Russia 🔗 Russia/mass media in Russia 🔗 Internet culture 🔗 New York City 🔗 Biography/science and academia

Ilya Zhitomirskiy (12 October 1989 – 12 November 2011) was a Russian-American software developer and entrepreneur. Zhitomirskiy was a co-founder and developer of the Diaspora social network and the Diaspora free software that powers it.

🔗 Birds

Brood parasites are organisms that rely on others to raise their young. The strategy appears among birds, insects and fish. The brood parasite manipulates a host, either of the same or of another species, to raise its young as if it were its own, using brood mimicry, for example by having eggs that resemble the host's (egg mimicry).

Brood parasitism relieves the parasitic parents from the investment of rearing young or building nests for the young, enabling them to spend more time on other activities such as foraging and producing further offspring. Bird parasite species mitigate the risk of egg loss by distributing eggs amongst a number of different hosts. As this behaviour damages the host, it often results in an evolutionary arms race between parasite and host as the pair of species coevolve.

The strength of defenses and counter-adaptation rely on the host/parasitic species' ability to evolve; some host species have very strong rejection defenses resulting in the parasitic species evolving to have very close mimicry. In other species, hosts do not show rejection defenses and as a result, the parasitic species will show no evolved trait (example: egg mimicry).

🔗 Anthropology 🔗 Athletics 🔗 Running 🔗 Evolutionary biology

The endurance running hypothesis is the hypothesis that the evolution of certain human characteristics can be explained as adaptations to long-distance running. The hypothesis suggests that endurance running played an important role for early hominins in obtaining food. Researchers have proposed that endurance running began as an adaptation for scavenging and later for persistence hunting.