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π Actuarial Notation
Actuarial notation is a shorthand method to allow actuaries to record mathematical formulas that deal with interest rates and life tables.
Traditional notation uses a halo system where symbols are placed as superscript or subscript before or after the main letter. Example notation using the halo system can be seen below.
Various proposals have been made to adopt a linear system where all the notation would be on a single line without the use of superscripts or subscripts. Such a method would be useful for computing where representation of the halo system can be extremely difficult. However, a standard linear system has yet to emerge.
Discussed on
- "Actuarial Notation" | 2021-09-21 | 78 Upvotes 19 Comments
π Hacker Koan
The Jargon File is a glossary and usage dictionary of slang used by computer programmers. The original Jargon File was a collection of terms from technical cultures such as the MIT AI Lab, the Stanford AI Lab (SAIL) and others of the old ARPANET AI/LISP/PDP-10 communities, including Bolt, Beranek and Newman, Carnegie Mellon University, and Worcester Polytechnic Institute. It was published in paperback form in 1983 as The Hacker's Dictionary (edited by Guy Steele), revised in 1991 as The New Hacker's Dictionary (ed. Eric S. Raymond; third edition published 1996).
The concept of the file began with the Tech Model Railroad Club (TMRC) that came out of early PDP-1 and TX-0 hackers in the 1950s, where the term hacker emerged and the ethic, philosophies and some of the nomenclature emerged.
Discussed on
- "Hacker Koan" | 2014-03-23 | 15 Upvotes 15 Comments
- "Hacker Koan" | 2010-07-31 | 50 Upvotes 7 Comments
π Main Core β database of US citizens believed to be threats to national security
Main Core is the code name of an American governmental database that is believed to have been in existence since the 1980s. It is believed that Main Core is a federal database containing personal and financial data of millions of United States citizens believed to be threats to national security.
Discussed on
- "Main Core β database of US citizens believed to be threats to national security" | 2013-06-14 | 216 Upvotes 134 Comments
π List of U.S. states and territories by net migration
This is a list of U.S. states and the District of Columbia by annual net migration. The first table lists U.S. states and the District of Columbia by annual net domestic migration, while the second table lists U.S. states and the District of Columbia by annual net international migration. There is a separate table for the U.S. territories. The term net domestic migration describes the total number of people moving to a state from another state minus people moving to another state from that state. The term net international migration describes the total number of people moving to a state from another country minus people moving to another country from that state.
Discussed on
- "List of U.S. states and territories by net migration" | 2022-02-22 | 26 Upvotes 8 Comments
π Gresham's Law
In economics, Gresham's law is a monetary principle stating that "bad money drives out good". For example, if there are two forms of commodity money in circulation, which are accepted by law as having similar face value, the more valuable commodity will gradually disappear from circulation.
The law was named in 1860 by Henry Dunning Macleod, after Sir Thomas Gresham (1519β1579), who was an English financier during the Tudor dynasty. However, the concept itself had been previously expressed by others, including by Aristophanes in his play The Frogs, which dates from around the end of the 5th century BC, in the 14th century by Nicole Oresme c.β1350, in his treatise On the Origin, Nature, Law, and Alterations of Money, and by jurist and historian Al-Maqrizi (1364β1442) in the Mamluk Empire; and in 1519 by Nicolaus Copernicus in a treatise called Monetae cudendae ratio For this reason, it is occasionally known as the GreshamβCopernicus' law.
Discussed on
- "Gresham's Law" | 2020-03-15 | 33 Upvotes 7 Comments
π The Power Elite
The Power Elite is a 1956 book by sociologist C. Wright Mills, in which Mills calls attention to the interwoven interests of the leaders of the military, corporate, and political elements of society and suggests that the ordinary citizen in modern times is a relatively powerless subject of manipulation by those three entities.
π The Trundle
The Trundle is an Iron Age hillfort on St Roche's Hill about 4 miles (6Β km) north of Chichester, Sussex, England, built on the site of a causewayed enclosure, a form of early Neolithic earthwork found in northwestern Europe. Causewayed enclosures were built in England from shortly before 3700 BC until about 3300 BC; they are characterized by the full or partial enclosure of an area with ditches that are interrupted by gaps, or causeways. Their purpose is not known; they may have been settlements, meeting places, or ritual sites. Hillforts were built as early as 1000 BC, in the Late Bronze Age, and continued to be built through the Iron Age until shortly before the Roman occupation. A chapel dedicated to St Roche was built on the hill around the end of the 14th century; it was in ruins by 1570. A windmill and a beacon were subsequently built on the hill. The site was occasionally used as a meeting place in the post-medieval period.
The hillfort is still a substantial earthwork, but the Neolithic site was unknown until 1925 when archaeologist O.G.S. Crawford obtained an aerial photograph of the Trundle, clearly showing additional structures inside the ramparts of the hillfort. Causewayed enclosures were new to archaeology at the time, with only five known by 1930, and the photograph persuaded archaeologist E. Cecil Curwen to excavate the site in 1928 and 1930. These early digs established a construction date of about 500 BC to 100 BC for the hillfort and proved the existence of the Neolithic site. In 2011, the Gathering Time project published an analysis of radiocarbon dates from almost forty British causewayed enclosures, including some from the Trundle. The conclusion was that the Neolithic part of the site was probably constructed no earlier than the mid-fourth millennium BC. A review of the site in 1995 by Alastair Oswald noted the presence of fifteen possible Iron Age house platforms within the hillfort's ramparts.
Discussed on
- "The Trundle" | 2022-01-16 | 35 Upvotes 6 Comments
π Siwa Oasis
The Siwa Oasis (Arabic: ΩΨ§ΨΨ© Ψ³ΩΩΨ©β, WΔαΈ₯at SΔ«wah, IPA:Β [ΛwΓ¦ΛΔ§et ΛsiΛwΓ¦]; Coptic: β²₯β²β²β²©β²Ο© Siwah; Berber languages: Isiwan, β΅β΅β΅β΅‘β΄°β΅ ) is an urban oasis in Egypt between the Qattara Depression and the Great Sand Sea in the Western Desert, 50Β km (30Β mi) east of the Libyan border, and 560Β km (348Β mi) from Cairo. About 80Β km (50Β mi) in length and 20Β km (12Β mi) wide, Siwa Oasis is one of Egypt's most isolated settlements with about 33,000 people, mostly Berbers, who developed a unique and isolated desert culture and a distinct dialect and language different than all other dialects called Siwi, they are also fluent in the Egyptian dialect of Arabic which is called "Masry" meaning Egyptian.
Its fame lies primarily in its ancient role as the home to an oracle of Ammon, the ruins of which are a popular tourist attraction which gave the oasis its ancient name Oasis of Amun Ra. Historically, it was part of Ancient Egypt.
Discussed on
- "Siwa Oasis" | 2019-07-13 | 35 Upvotes 10 Comments
π Ladder Paradox
The ladder paradox (or barn-pole paradox) is a thought experiment in special relativity. It involves a ladder, parallel to the ground, travelling horizontally at relativistic speed (near the speed of light) and therefore undergoing a Lorentz length contraction. The ladder is imagined passing through the open front and rear doors of a garage or barn which is shorter than its rest length, so if the ladder was not moving it would not be able to fit inside. To a stationary observer, due to the contraction, the moving ladder is able to fit entirely inside the building as it passes through. On the other hand, from the point of view of an observer moving with the ladder, the ladder will not be contracted, and it is the building which will be Lorentz contracted to an even smaller length. Therefore, the ladder will not be able to fit inside the building as it passes through. This poses an apparent discrepancy between the realities of both observers.
This apparent paradox results from the mistaken assumption of absolute simultaneity. The ladder is said to fit into the garage if both of its ends can be made to be simultaneously inside the garage. The paradox is resolved when it is considered that in relativity, simultaneity is relative to each observer, making the answer to whether the ladder fits inside the garage also relative to each of them.
Discussed on
- "Ladder Paradox" | 2023-10-18 | 17 Upvotes 5 Comments
π Kevinism
In German, Kevinismus ("Kevinism") is the negative preconception German people have of Germans with trendy, exotic-sounding first names considered to be an indicator of a low social class. The protypical example is Kevin, which like most such names came to Germany from Anglo-American culture. Sometimes Chantalismus ("Chantalism") is used as a female equivalent, from the French name Chantal.
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- "Kevinism" | 2022-08-23 | 37 Upvotes 1 Comments