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🔗 Chemicals

Pentaborane(9) is an inorganic compound with the formula B₅H₉. It is one of the most common boron hydride clusters, although it is a highly reactive compound. Because of its high reactivity with oxygen, it was once evaluated as rocket or jet fuel. Like many of the smaller boron hydrides, pentaborane is colourless, diamagnetic, and volatile. It is related to pentaborane(11) (B₅H₁₁).

🔗 California 🔗 Companies 🔗 California/San Francisco Bay Area 🔗 Video games

Zynga Inc. is an American social game developer running social video game services and founded in April 2007 with headquarters in San Francisco, California, United States. The company primarily focuses on mobile and social networking platforms. Zynga states its mission as "connecting the world through games."

Zynga launched its best-known game, FarmVille, on Facebook in June 2009, reaching 10 million daily active users (DAU) within six weeks. As of August 2017, Zynga had 30 million monthly active users (MAU). In 2017 its most successful games were Zynga Poker and Words with Friends 2, with about 57 million games being played at any given moment; and CSR Racing 2, the most popular racing game on mobile devices.

Zynga began trading on NASDAQ December 16, 2011, under the ticker ZNGA.

🔗 Economics

Veblen goods are types of luxury goods for which the quantity demanded increases as the price increases, an apparent contradiction of the law of demand, resulting in an upward-sloping demand curve. A higher price may make a product desirable as a status symbol in the practices of conspicuous consumption and conspicuous leisure. A product may be a Veblen good because it is a positional good, something few others can own.

Veblen goods are named after American economist Thorstein Veblen, who first identified conspicuous consumption as a mode of status-seeking in The Theory of the Leisure Class (1899). A corollary of the Veblen effect is that lowering the price decreases the quantity demanded.

🔗 Physics 🔗 Physics/Fluid Dynamics

The tea leaf paradox is a phenomenon where tea leaves in a cup of tea migrate to the center and bottom of the cup after being stirred rather than being forced to the edges of the cup, as would be expected in a spiral centrifuge. The correct physical explanation of the paradox was for the first time given by James Thomson in 1857. He correctly connected the appearance of secondary flow (in both Earth atmosphere and tea cup) with ″friction on the bottom″. The formation of secondary flows in an annular channel was theoretically treated by Boussinesq as early as in 1868. The migration of near-bottom particles in river-bend flows was experimentally investigated by A. Ya. Milovich in 1913. The solution first came from Albert Einstein in a 1926 paper in which he explained the erosion of river banks, and repudiated Baer's law.

🔗 Soviet Union 🔗 Russia 🔗 Russia/technology and engineering in Russia 🔗 Environment 🔗 Military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry 🔗 Military history/Cold War 🔗 Russia/Russian, Soviet, and CIS military history 🔗 Military history/Russian, Soviet and CIS military history 🔗 Russia/history of Russia

The Soviet RDS-202 hydrogen bomb (code name Ivan or Vanya), known by Western nations as Tsar Bomba (Russian: Царь-бо́мба, tr. Tsar'-bómba, IPA: [t͡sarʲ ˈbombə], lit. 'Tsar bomb'), was the most powerful nuclear weapon ever created. Tested on 30 October 1961 as an experimental verification of calculation principles and multi-stage thermonuclear weapon designs, it also remains the most powerful human-made explosive ever detonated.

The bomb was detonated at the Sukhoy Nos ("Dry Nose") cape of Severny Island, Novaya Zemlya, 15 km (9.3 mi) from Mityushikha Bay, north of Matochkin Strait. The detonation was secret but was detected by US Intelligence agencies. The US apparently had an instrumented KC-135R aircraft (Operation SpeedLight) in the area of the test – close enough to have been scorched by the blast.

The bhangmeter results and other data suggested the bomb yielded about 58 megatons of TNT [Mt] (240 PJ), and that was the accepted yield in technical literature until 1991 when Soviet scientists revealed that their instruments indicated a yield of 50 Mt (210 PJ). As they had the instrumental data and access to the test site, their yield figure has been accepted as more accurate. In theory, the bomb would have had a yield in excess of 100 Mt (420 PJ) if it had included a uranium-238 tamper but, because only one bomb was built, that capability has never been demonstrated.

The remaining bomb casings are located at the Russian Atomic Weapon Museum in Sarov and the Museum of Nuclear Weapons, All-Russian Research Institute of Technical Physics, at Snezhinsk.

🔗 Books 🔗 Women's History

Around the World in Seventy-Two Days is an 1890 book by journalist Elizabeth Jane Cochrane, writing under her pseudonym, Nellie Bly. The chronicle details her 72-day trip around the world, which was inspired by the book, Around the World in Eighty Days by Jules Verne. She carried out the journey for Joseph Pulitzer's tabloid newspaper, the New York World.

🔗 Biography 🔗 New York City 🔗 Biography/arts and entertainment 🔗 Visual arts

Tom Sachs (born July 26, 1966) is an American contemporary artist who lives and works in New York City.

🔗 Mathematics

In number theory, Mills' constant is defined as the smallest positive real number A such that the floor function of the double exponential function

${\displaystyle \lfloor A^{3^{n}}\rfloor }$

is a prime number, for all natural numbers n. This constant is named after William H. Mills who proved in 1947 the existence of A based on results of Guido Hoheisel and Albert Ingham on the prime gaps. Its value is unknown, but if the Riemann hypothesis is true, it is approximately 1.3063778838630806904686144926... (sequence A051021 in the OEIS).

🔗 Automobiles

A hemispherical combustion chamber is a type of combustion chamber in a reciprocating internal combustion engine with a domed cylinder head. An engine featuring this type of hemispherical chamber is known as a hemi engine.

🔗 Finance & Investment 🔗 New York City 🔗 Fraternities and Sororities

Kappa Beta Phi (ΚΒΦ) is a secret society with at least one surviving chapter, based on Wall Street in New York City, that is made up of high-ranking financial executives. The purpose of the organization today is largely social and honorific. The current honor society meets once a year at a black-tie dinner to induct new members.