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🔗 Transport 🔗 Trains

The Cosmopolitan Railway was a proposed global railroad network advocated by William Gilpin, formerly the first territorial governor of Colorado (1861–62), in his 1890 treatise Cosmopolitan Railway: Compacting and Fusing Together All the World's Continents. Gilpin named his capital city of Denver as the "railroad centre of the West".

🔗 Korea 🔗 Business 🔗 Japan 🔗 Japan/Business and economy

Simultaneous recruiting of new graduates or periodic recruiting of new graduates (新卒一括採用, Shinsotsu-ikkatsu-saiyō) is the custom that companies hire new graduates all at once and employ them. This custom was unique to Japan and South Korea. A 2010 age discrimination law enforced in South Korea bans employers from discriminating against job-seekers who have not recently graduated from high school or university. Japan is now the only country practising this custom; however, in 2018, the Japan Business Federation (Keidanren) announced that its 1,600 member companies, which represent a large portion of Japan's big business companies, would no longer be required to follow the custom from 2020 onwards.

🔗 Physics 🔗 Physics/relativity

In physics, there is a speculative hypothesis that, if there were a black hole with the same mass, charge and angular momentum as an electron, it would share other properties of the electron. Most notably, Brandon Carter showed in 1968 that the magnetic moment of such an object would match that of an electron. This is interesting because calculations ignoring special relativity and treating the electron as a small rotating sphere of charge give a magnetic moment roughly half the experimental value (see Gyromagnetic ratio).

However, Carter's calculations also show that a would-be black hole with these parameters would be "super-extremal". Thus, unlike a true black hole, this object would display a naked singularity, meaning a singularity in spacetime not hidden behind an event horizon. It would also give rise to closed timelike curves.

Standard quantum electrodynamics (QED), currently the most comprehensive theory of particles, treats the electron as a point particle. There is no evidence that the electron is a black hole (or naked singularity) or not. Furthermore, since the electron is quantum-mechanical in nature, any description purely in terms of general relativity is paradoxical until a better model based on understanding of quantum nature of blackholes and gravitational behaviour of quantum particles is developed by research. Hence, the idea of a black hole electron remains strictly hypothetical.

🔗 Physics 🔗 Electronics 🔗 Professional sound production

Pink noise or ​¹⁄_f noise is a signal or process with a frequency spectrum such that the power spectral density (energy or power per frequency interval) is inversely proportional to the frequency of the signal. In pink noise, each octave (halving or doubling in frequency) carries an equal amount of noise energy.

Pink noise is one of the most common signals in biological systems.

The name arises from the pink appearance of visible light with this power spectrum. This is in contrast with white noise which has equal intensity per frequency interval.

🔗 Mathematics

In mathematics, Young's lattice is a partially ordered set and a lattice that is formed by all integer partitions. It is named after Alfred Young, who, in a series of papers On quantitative substitutional analysis, developed representation theory of the symmetric group. In Young's theory, the objects now called Young diagrams and the partial order on them played a key, even decisive, role. Young's lattice prominently figures in algebraic combinatorics, forming the simplest example of a differential poset in the sense of Stanley (1988). It is also closely connected with the crystal bases for affine Lie algebras.

🔗 New York City 🔗 Architecture

75½ Bedford Street is a house located in the West Village neighborhood of New York City that is only 9 feet 6 inches (2.9 meters) wide. Built in 1873, it is often described as the narrowest house in New York. Its past tenants have included Edna St. Vincent Millay, Ann McGovern, cartoonist William Steig and anthropologist Margaret Mead. It is sometimes referred to as the Millay House, indicated by a plaque on the outside of the house. The house is located in the Greenwich Village Historic District, but is not an individually designated New York City Landmark.

🔗 Software 🔗 Software/Computing

A door in a bulletin board system (BBS) is an interface between the BBS software and an external application. The term is also used to refer to the external application, a computer program that runs outside of the main bulletin board program. Sometimes called external programs, doors are the most common way to add games, utilities, and other extensions to BBSes. Because BBSes typically depended on the telephone system, BBSes and door programs tended to be local in nature, unlike modern Internet games and applications.

From the 1990s on, most BBS software had the capability to "drop to" doors. Several standards were developed for passing connection and user information to doors; this was usually done with "dropfiles", small binary or text files dropped into known locations in the BBS's file system. Most doors were responsible for operating the serial port or other communications device directly until returning control to the BBS. Later development of FOSSIL drivers have allowed both BBSes and their doors to communicate without being responsible for direct operation of the communications hardware.

🔗 Spaceflight 🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Military history/Military science, technology, and theory 🔗 Moon 🔗 Military history/Cold War 🔗 Cold War 🔗 Solar System 🔗 Solar System/Moon

Project A119, also known as A Study of Lunar Research Flights, was a top-secret plan developed in 1958 by the United States Air Force. The aim of the project was to detonate a nuclear bomb on the Moon, which would help in answering some of the mysteries in planetary astronomy and astrogeology. If the explosive device detonated on the surface, not in a lunar crater, the flash of explosive light would have been faintly visible to people on Earth with their naked eye, a show of force resulting in a possible boosting of domestic morale in the capabilities of the United States, a boost that was needed after the Soviet Union took an early lead in the Space Race and was also working on a similar project.

The project was never carried out, being cancelled primarily out of a fear of a negative public reaction, with the potential militarization of space that it would also have signified, and because a Moon landing would undoubtedly be a more popular achievement in the eyes of the American and international public alike. A similar project by the Soviet Union also never came to fruition.

The existence of the US project was revealed in 2000 by a former executive at the National Aeronautics and Space Administration (NASA), Leonard Reiffel, who led the project in 1958. A young Carl Sagan was part of the team responsible for predicting the effects of a nuclear explosion in vacuum and low gravity and in evaluating the scientific value of the project. The project documents remained secret for nearly 45 years, and despite Reiffel's revelations, the United States government has never officially recognized its involvement in the study.

🔗 Computing

In computer storage, Bélády's anomaly is the phenomenon in which increasing the number of page frames results in an increase in the number of page faults for certain memory access patterns. This phenomenon is commonly experienced when using the first-in first-out (FIFO) page replacement algorithm. In FIFO, the page fault may or may not increase as the page frames increase, but in Optimal and stack-based algorithms like LRU, as the page frames increase the page fault decreases. László Bélády demonstrated this in 1969.

In common computer memory management, information is loaded in specific-sized chunks. Each chunk is referred to as a page. Main memory can hold only a limited number of pages at a time. It requires a frame for each page it can load. A page fault occurs when a page is not found, and might need to be loaded from disk into memory.

When a page fault occurs and all frames are in use, one must be cleared to make room for the new page. A simple algorithm is FIFO: whichever page has been in the frames the longest is the one that is cleared. Until Bélády's anomaly was demonstrated, it was believed that an increase in the number of page frames would always result in the same number of or fewer page faults.

🔗 Military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/World War I 🔗 Military history/German military history 🔗 Birds 🔗 Photography 🔗 Photography/History of photography 🔗 Military history/European military history

Pigeon photography is an aerial photography technique invented in 1907 by the German apothecary Julius Neubronner, who also used pigeons to deliver medications. A homing pigeon was fitted with an aluminium breast harness to which a lightweight time-delayed miniature camera could be attached. Neubronner's German patent application was initially rejected, but was granted in December 1908 after he produced authenticated photographs taken by his pigeons. He publicized the technique at the 1909 Dresden International Photographic Exhibition, and sold some images as postcards at the Frankfurt International Aviation Exhibition and at the 1910 and 1911 Paris Air Shows.

Initially, the military potential of pigeon photography for aerial reconnaissance appeared interesting. Battlefield tests in World War I provided encouraging results, but the ancillary technology of mobile dovecotes for messenger pigeons had the greatest impact. Owing to the rapid perfection of aviation during the war, military interest in pigeon photography faded and Neubronner abandoned his experiments. The idea was briefly resurrected in the 1930s by a Swiss clockmaker, and reportedly also by the German and French militaries. Although war pigeons were deployed extensively during World War II, it is unclear to what extent, if any, birds were involved in aerial reconnaissance. The United States Central Intelligence Agency (CIA) later developed a battery-powered camera designed for espionage pigeon photography; details of its use remain classified.

The construction of sufficiently small and light cameras with a timer mechanism, and the training and handling of the birds to carry the necessary loads, presented major challenges, as did the limited control over the pigeons' position, orientation and speed when the photographs were being taken. In 2004, the British Broadcasting Corporation (BBC) used miniature television cameras attached to falcons and goshawks to obtain live footage, and today some researchers, enthusiasts and artists similarly deploy crittercams with various species of animals.