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🔗 Metalworking

Biomachining is the machining process of using lithotropic bacteria to remove material from metal parts, contrasted with chemical machining methods such as chemical milling and physical machining methods such as milling. Certain bacteria, such as Thiobacillus ferrooxidans and Thiobacillus thiooxidans, which are also used in the mineral refinement process of bioleaching, utilize the chemical energy from oxidation of iron or copper to fix carbon dioxide from the air. A metal object, when placed in a culture fluid containing these metal-metabolizing bacteria, will have material removed from its surface over time.

Biomachining is ideal for micromachining due to its very low material removal rate. In addition, biomachining is less likely to leave an undesirable surface finish; neither chemical nor physical energy is concentrated on the cutting area, so the possibility of a damaged or burned surface is slim.

This process has been successfully used to cut both pure iron and pure copper.

🔗 Mathematics

In number theory, a weird number is a natural number that is abundant but not semiperfect.

In other words, the sum of the proper divisors (divisors including 1 but not itself) of the number is greater than the number, but no subset of those divisors sums to the number itself.

🔗 Canada 🔗 Minnesota 🔗 Canada/Geography of Canada 🔗 National Register of Historic Places

The northwesternmost point of the Lake of the Woods was a critical landmark for the boundary between U.S. territory and the British possessions to the north. This point was referred to in the Treaty of Paris in 1783 and in later treaties including the Treaty of 1818. This point lies at the corner of the Northwest Angle of Minnesota and is thus the northernmost point in the lower 48 United States. After Canadian Confederation, the point became the basis for the border between Manitoba and Ontario.

The "northwesternmost point" of the lake had not yet been identified when it was referenced in treaties defining the border between the US and Britain; it was simply an easily described abstraction based on a large landmark. The best maps at the time of the original negotiation depicted the lake as a simple oval. However, although the southern portion of the lake is easily mapped, to the north it becomes a complex tangle of bays, peninsulas, and islands, with many adjacent bodies of water separated or connected by narrow isthmuses or straits. An 1822 survey crew declared the referenced point impossible to determine. In 1824, British explorer David Thompson was hired to identify it. Thompson mapped the lake and found four possibilities, but did not conclusively declare one location.

In 1825, German astronomer in British service Dr. Johann Ludwig Tiarks surveyed the lake. Tiarks identified two possibilities for the northwesternmost point on the lake, based on Thompson's maps: the Angle Inlet and Rat Portage. To determine which point was the most northwestern, he drew a line from each point in the southwest-northeast direction. If the line intersected the lake at any point, it was not the most northwestern point, as shown in the example diagram here. Tiarks determined that the only such line that did not intersect the lake was at the edge of a pond on the Angle Inlet. (A 1940 academic study documents this point as being in the immediate vicinity of 49°23′51.324″N 95°9′12.20783″W (NAD83).)

Under the 1783 treaty, the international border would have run due west from this point to the Mississippi River. As this was determined to be geographically impossible (the Mississippi begins further south), under the 1818 treaty the international border instead ran from the point determined by Tiarks, to the 49th parallel. (It was not known at the time whether that was to the north or – in fact – the south.) From there it ran due west to the Rocky Mountains (and later, the Pacific coast).

Tiarks' point, however, created problems, because the 1818 treaty called for the border to run directly north–south from it. South of that point, the channel of the Northwest Angle Inlet meandered east and west, crossing the border five times, thereby creating two small enclaves of water areas totaling two and a half acres that belonged to the United States but were surrounded by Canadian waters. A 1925 treaty addressed this by adopting the southernmost of the points where the channel and the border intersected – approximately 5,000 ft (1,500 m) south of Tiarks' point – as the new "northwesternmost point". The new northwesternmost point thus became 49°23′4.14″N 95°9′11.34″W, based on the NAD27 datum, which is equivalent to 49°23′4.12373″N 95°9′12.20783″W under the modern NAD83 datum.

🔗 Biography 🔗 Military history 🔗 Military history/Military biography 🔗 Military history/World War II

Sir Basil Zaharoff, GCB, GBE, born Vasileios Zacharias (Greek: Βασίλειος Zαχαρίας Ζαχάρωφ; October 6, 1849 – November 27, 1936), was a Greek arms dealer and industrialist. One of the richest men in the world during his lifetime, Zaharoff was described as a "merchant of death" and "mystery man of Europe". His success was forged through his cunning, often aggressive and sharp, business tactics. These included the sale of arms to opposing sides in conflicts, sometimes delivering fake or faulty machinery and skilfully using the press to attack business rivals.

Zaharoff maintained close contacts with many powerful political leaders, including British Prime Minister David Lloyd George, Greek Prime Minister Eleftherios Venizelos and Ottoman Sultan Abdul Hamid II; he served as a primary inspiration for Ian Fleming's fictional James Bond villain Ernst Stavro Blofeld.

🔗 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.

🔗 United States 🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Law Enforcement

The Posse Comitatus Act is a United States federal law (18 U.S.C. § 1385, original at 20 Stat. 152) signed on June 18, 1878, by President Rutherford B. Hayes. The purpose of the act – in concert with the Insurrection Act of 1807 – is to limit the powers of the federal government in using federal military personnel to enforce domestic policies within the United States. It was passed as an amendment to an army appropriation bill following the end of Reconstruction and was updated in 1956 and 1981.

The act specifically applies only to the United States Army and, as amended in 1956, the United States Air Force. Although the act does not explicitly mention the United States Navy and the United States Marine Corps, the Department of the Navy has prescribed regulations that are generally construed to give the act force with respect to those services as well. The act does not prevent the Army National Guard or the Air National Guard under state authority from acting in a law enforcement capacity within its home state or in an adjacent state if invited by that state's governor. The United States Coast Guard (under the Department of Homeland Security) and United States Space Force (under the Department of the Air Force) are not covered by the Posse Comitatus Act either, primarily because although both are armed services, they also have maritime and space law enforcement missions respectively.

The title of the act comes from the legal concept of posse comitatus, the authority under which a county sheriff, or other law officer, conscripts any able-bodied person to assist in keeping the peace.

🔗 Radio 🔗 BBC 🔗 Radio/UK Radio

The Wartime Broadcasting Service is a service of the BBC that is intended to broadcast in the United Kingdom either after a nuclear attack or if conventional bombing destroyed regular BBC facilities in a conventional war.

🔗 Military history

🔗 Philosophy 🔗 Philosophy/Philosophy of religion

The self-referencing doomsday argument rebuttal is an attempt to refute the doomsday argument (that there is a credible link between the brevity of the human race's existence and its expected extinction) by applying the same reasoning to the lifetime of the doomsday argument itself.

The first researchers to write about this were P. T. Landsberg and J. N. Dewynne in 1997; they applied belief in the doomsday argument to itself, and claimed that a paradox results.

🔗 Women's History 🔗 Iceland

On 24 October 1975, Icelandic women went on strike for the day to "demonstrate the indispensable work of women for Iceland’s economy and society" and to "protest wage discrepancy and unfair employment practices". It was then publicized domestically as Women's Day Off (Kvennafrídagurinn). Participants, led by women's organizations, did not go to their paid jobs and did not do any housework or child-rearing for the whole day. Ninety percent of Iceland's female population participated in the strike. Iceland's parliament passed a law guaranteeing equal pay the following year.