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https://en.wikipedia.org/wiki/L%C3%A1szl%C3%B3%20Fejes%20T%C3%B3th	László Fejes Tóth (, 12 March 1915 – 17 March 2005) was a Hungarian mathematician who specialized in geometry. He proved that a lattice pattern is the most efficient way to pack centrally symmetric convex sets on the Euclidean plane (a generalization of Thue's theorem, a 2-dimensional analog of the Kepler conjecture). He also investigated the sphere packing problem. He was the first to show, in 1953, that proof of the Kepler conjecture can be reduced to a finite case analysis and, later, that the problem might be solved using a computer. He was a member of the Hungarian Academy of Sciences (from 1962) and a director of the Alfréd Rényi Institute of Mathematics (1970-1983). He received both the Kossuth Prize (1957) and State Award (1973). Together with H.S.M. Coxeter and Paul Erdős, he laid the foundations of discrete geometry. Early life and career As described in a 1999 interview with István Hargittai, Fejes Tóth's father was a railway worker, who advanced in his career within the railway organization ultimately to earn a doctorate in law. Fejes Tóth's mother taught Hungarian and German literature in a high school. The family moved to Budapest, when Fejes Tóth was five; there he attended elementary school and high school—the Széchenyi István Reálgimnázium—where his interest in mathematics began. Fejes Tóth attended Pázmány Péter University, now the Eötvös Loránd University. As a freshman, he developed a generalized solution regarding Cauchy exponential series, which he published in the proceedings of the French Academy of Sciences—1935. He then received his doctorate at Pázmány Péter University, under the direction of Lipót Fejér. After university, he served as a soldier for two years, but received a medical exemption. In 1941 he joined the University of Kolozsvár (Cluj). It was here that he became interested in packing problems. In 1944, he returned to Budapest to teach mathematics at Árpád High School. Between 1946 and 1949 he lectured at Pázmány Péter Un
https://en.wikipedia.org/wiki/Artin%20approximation%20theorem	In mathematics, the Artin approximation theorem is a fundamental result of in deformation theory which implies that formal power series with coefficients in a field k are well-approximated by the algebraic functions on k. More precisely, Artin proved two such theorems: one, in 1968, on approximation of complex analytic solutions by formal solutions (in the case ); and an algebraic version of this theorem in 1969. Statement of the theorem Let denote a collection of n indeterminates, the ring of formal power series with indeterminates over a field k, and a different set of indeterminates. Let be a system of polynomial equations in , and c a positive integer. Then given a formal power series solution , there is an algebraic solution consisting of algebraic functions (more precisely, algebraic power series) such that Discussion Given any desired positive integer c, this theorem shows that one can find an algebraic solution approximating a formal power series solution up to the degree specified by c. This leads to theorems that deduce the existence of certain formal moduli spaces of deformations as schemes. See also: Artin's criterion. Alternative statement The following alternative statement is given in Theorem 1.12 of . Let be a field or an excellent discrete valuation ring, let be the henselization at a prime ideal of an -algebra of finite type, let m be a proper ideal of , let be the m-adic completion of , and let be a functor sending filtered colimits to filtered colimits (Artin calls such a functor locally of finite presentation). Then for any integer c and any , there is a such that . See also Ring with the approximation property Popescu's theorem Artin's criterion References Moduli theory Commutative algebra Theorems about algebras
https://en.wikipedia.org/wiki/Scott%20Swedorski	Scott Swedorski is the founder of Tucows (The Ultimate Collection of Winsock Software), a large Internet domain name reseller, and Internet service provider. History Scott served in the military and then received an associate degree from Mott Community College in Flint. In 1993 he worked for the Flint Area Library Online Network (FALCON) Swedorski felt there was a need for public access to Internet-related software. Working from home, he created a site to provide the public with free and easily downloaded software. In 2002, Swedorski received the lifetime achievement award from the Shareware Industry Awards Foundation (SIAF) for his work with shareware software authors. Swedorski retired from Tucows in 2003 and launched a new software promotions company. He is also the Vice President of distribution and marketing at CoffeeCup Software, where he helped co-found the Organization of Independent Software Vendors. Scott also runs FileLight.com, a large shareware download site. References External links Tucows Organization of Independent Software Vendors 1970 births Living people Tucows
https://en.wikipedia.org/wiki/DOS%20XL	DOS XL is a discontinued Disk Operating System (DOS) written by Paul Laughton, Mark Rose, Bill Wilkinson, and Mike Peters and published by Optimized Systems Software (OSS) for the Atari 8-bit family of home computers. It was designed to be compatible with Atari DOS which came shipped with Atari, Inc.'s disk drives, which had also been written by the same team. Description Features A direct descendant of OS/A+, DOS XL provided additional features to Atari's equipped with floppy disk drives. These included single and double density support, a command-line mode (called the command processor or CP), a menu mode (an executable loaded in memory), batch file support, and support for XL extended memory and OSS SuperCartridge banked memory. Later versions included Axlon RamDisk support, Mosaic RamDisk support, BIT-3 support and BUG/65. In addition to supporting auto-booting AUTORUN.SYS files, DOS XL's batch features provided an auto-booting batch feature. Naming a batch file to STARTUP.EXC would have it execute batch commands on startup (same as OS/A+). Unfortunately, this feature wasn't compatible with some programs (e.g. AtariWriter). Distribution DOS XL was distributed on a flippy disk. One side had the single-density version, the other had the double-density version. As more features and add-ons were included, these were placed on the double-density side only due to lack of disk space. The manual for DOS XL was a subset of OS/A+. OSS considered the manual an "addendum" to OS/A+. Over 150+ pages, it was bound at the spine, not in loose-leaf form like the OS/A+ manual. DOS XL came in two versions, 2.20 and 2.30 (2.20 users had to pay $20 to upgrade to 2.30). The last version was 2.30P. DOS XL originally sold for $30, but the price later increased to $39. File writing verify was turned off in DOS XL. This was due to OSS's own experience that resulted in faster writes with virtually no risk of errors. The command file VERIFY.COM was included to reenable writes with ve
https://en.wikipedia.org/wiki/Glossary%20of%20category%20theory	This is a glossary of properties and concepts in category theory in mathematics. (see also Outline of category theory.) Notes on foundations: In many expositions (e.g., Vistoli), the set-theoretic issues are ignored; this means, for instance, that one does not distinguish between small and large categories and that one can arbitrarily form a localization of a category. Like those expositions, this glossary also generally ignores the set-theoretic issues, except when they are relevant (e.g., the discussion on accessibility.) Especially for higher categories, the concepts from algebraic topology are also used in the category theory. For that see also glossary of algebraic topology. The notations and the conventions used throughout the article are: [n] = {0, 1, 2, …, n}, which is viewed as a category (by writing .) Cat, the category of (small) categories, where the objects are categories (which are small with respect to some universe) and the morphisms functors. Fct(C, D), the functor category: the category of functors from a category C to a category D. Set, the category of (small) sets. sSet, the category of simplicial sets. "weak" instead of "strict" is given the default status; e.g., "n-category" means "weak n-category", not the strict one, by default. By an ∞-category, we mean a quasi-category, the most popular model, unless other models are being discussed. The number zero 0 is a natural number. A B C D E F G H I K L M N O P Q R S T U W Y Z Notes References A. Joyal, The theory of quasi-categories II (Volume I is missing??) Lurie, J., Higher Algebra Lurie, J., Higher Topos Theory Further reading Groth, M., A Short Course on ∞-categories Cisinski's notes History of topos theory http://plato.stanford.edu/entries/category-theory/ Emily Riehl, A leisurely introduction to simplicial sets Categorical Logic lecture notes by Steve Awodey (a detailed discussion of a 2-category) Category theory Wikipedia glossaries using description lis
https://en.wikipedia.org/wiki/AdBrite	AdBrite, Inc. was an online ad exchange, based in San Francisco, California, which was founded by Philip J. Kaplan and Gidon Wise in 2002. Founded as Marketbanker.com, the site was relaunched as AdBrite in 2004 as an advertising network and then in 2008 as an ad exchange. AdBrite remained an independent ad exchange, reaching more than 160 million U.S. unique visitors each month and providing site-level transparency, display and video capabilities, and an open platform for data providers and real-time bidders. AdBrite was led by Hardeep Bindra, CEO, and Joaquin Delgado, CTO, who had worked at Yahoo! Right Media, another ad exchange. It was backed by Sequoia Capital, and DAG Ventures. Closing In 2012, Hardeep Bindra joined AdBrite as its CEO and was tasked to sell the company or its assets. On January 28, 2013, AdBrite sent an email to all of its publishers and advertisers stating that it would cease operations as of February 1, 2013, after a deal to sell the company fell through. In addition, it laid off all 26 employees. Acquisition of IP Assets On June 20, 2013 SiteScout announced via press release the acquisition of certain intellectual property assets developed by AdBrite in a deal whose details remain confidential. See also Ad serving Advertising network Pay-per-click Website monetization References Additional sources Washington Post article San Francisco Business Times article CNET News article Techcrunch article The New York Times article Los Angeles Times article Wall Street Journal” article CNN article All Things D Article Online advertising services and affiliate networks Marketing companies established in 2002 2002 establishments in California
https://en.wikipedia.org/wiki/Dogic	The Dogic () is an icosahedron-shaped puzzle like the Rubik's Cube. The 5 triangles meeting at its tips may be rotated, or 5 entire faces (including the triangles) around the tip may be rotated. It has a total of 80 movable pieces to rearrange, compared to the 20 pieces in the Rubik's Cube. History The Dogic was patented by Zsolt and Robert Vecsei in Hungary on 20 October 1993. The patent was granted 28 July 1998 (HU214709). It was originally sold by VECSO in two variants under the names "Dogic" and "Dogic 2", but was only produced in quantities far short of the demand. In 2004, Uwe Mèffert acquired the plastic molds from its original manufacturer at the request of puzzle fans and collectors worldwide, and made another production run of the Dogics. These Dogics were first shipped in January 2005, and are now being sold by Meffert in his puzzle shop, Meffert's until September 2010 when the lack of interest for Meffert's Dogics made Uwe Meffert stop his Dogic production run. According to Uwe Mèffert, 2000 units have been produced by him. Description The basic design of the Dogic is an icosahedron cut into 60 triangular pieces around its 12 tips and 20 face centers. All 80 pieces can move relative to each other. There are also a good number of internal moving pieces inside the puzzle, which are necessary to keep it in one piece as its surface pieces are rearranged. There are two types of twists that it can undergo: a shallow twist which rotates the 5 triangles around a single tip, and a deep twist which rotates 5 entire faces (including the triangles around the tip) around the tip. The shallow twist moves the triangles between faces but keeps them around the same tip; the deeper twist moves the triangles between the 5 tips lying at the base of the rotated faces but keeps them on the same faces. Each triangle has a single color, while the face centers may have up to 3 colors, depending on the particular coloring scheme employed. Solutions The solutions for t
https://en.wikipedia.org/wiki/Entomophily	Entomophily or insect pollination is a form of pollination whereby pollen of plants, especially but not only of flowering plants, is distributed by insects. Flowers pollinated by insects typically advertise themselves with bright colours, sometimes with conspicuous patterns (honey guides) leading to rewards of pollen and nectar; they may also have an attractive scent which in some cases mimics insect pheromones. Insect pollinators such as bees have adaptations for their role, such as lapping or sucking mouthparts to take in nectar, and in some species also pollen baskets on their hind legs. This required the coevolution of insects and flowering plants in the development of pollination behaviour by the insects and pollination mechanisms by the flowers, benefiting both groups. Both the size and the density of a population are known to affect pollination and subsequent reproductive performance. Coevolution History The early spermatophytes (seed plants) were largely dependent on the wind to carry their pollen from one plant to another. Prior to the appearance of flowering plants some gymnosperms, such as Bennettitales, developed flower-like structures that were likely insect pollinated. Insects pollination for gymnosperms likely originated in the Permian period. Candidates for pollinators include extinct long proboscis insect groups, including Aneuretopsychid, Mesopsychid and Pseudopolycentropodid scorpionflies, Kalligrammatid and Paradoxosisyrine lacewings and Zhangsolvid flies, as well as some extant families that specialised on gymnosperms before switching to angiosperms, including Nemestrinid, Tabanid and Acrocerid flies. Living cycads have mutualistic relationships with specific insect species (typically beetles) which pollinate them. Such relationships extend back to at least the late Mesozoic, with both oedemerid beetles (which today are exclusively found on flowering plants) and boganiid beetles (which still pollinate cycads today) from the Cretaceous being
https://en.wikipedia.org/wiki/Seabird%20Colony%20Register	The Seabird Colony Register (SCR) is a database, managed by the British Joint Nature Conservation Committee, which contains counts of breeding seabirds at British seabird colonies made between 1969 and 1998, which is used for analysing past changes in breeding seabird numbers and changes in their colony size in Britain and Ireland. Data included in the SCR include results of two complete seabird censuses of Britain and Ireland: Operation Seafarer (1969/70) and the Seabird Colony Register Census (1985–1987), as well as ad hoc counts and counts from other surveys. Data are held for all 25 species of seabird breeding throughout Britain and Ireland. The SCR has been partially superseded by the Seabird 2000 database. References Conservation in the United Kingdom Databases in the United Kingdom Birds in the United Kingdom Bird censuses
https://en.wikipedia.org/wiki/IOPS	Input/output operations per second (IOPS, pronounced eye-ops) is an input/output performance measurement used to characterize computer storage devices like hard disk drives (HDD), solid state drives (SSD), and storage area networks (SAN). Like benchmarks, IOPS numbers published by storage device manufacturers do not directly relate to real-world application performance. Background To meaningfully describe the performance characteristics of any storage device, it is necessary to specify a minimum of three metrics simultaneously: IOPS, response time, and (application) workload. Absent simultaneous specifications of response-time and workload, IOPS are essentially meaningless. In isolation, IOPS can be considered analogous to "revolutions per minute" of an automobile engine i.e. an engine capable of spinning at 10,000 RPMs with its transmission in neutral does not convey anything of value, however an engine capable of developing specified torque and horsepower at a given number of RPMs fully describes the capabilities of the engine. The specific number of IOPS possible in any system configuration will vary greatly, depending upon the variables the tester enters into the program, including the balance of read and write operations, the mix of sequential and random access patterns, the number of worker threads and queue depth, as well as the data block sizes. There are other factors which can also affect the IOPS results including the system setup, storage drivers, OS background operations etc. Also, when testing SSDs in particular, there are preconditioning considerations that must be taken into account. Performance characteristics The most common performance characteristics measured are sequential and random operations. Sequential operations access locations on the storage device in a contiguous manner and are generally associated with large data transfer sizes, e.g. ≥ 128 kB. Random operations access locations on the storage device in a non-contiguous manner and a
https://en.wikipedia.org/wiki/XML%20Interface%20for%20Network%20Services	XML Interface for Network Services (XINS) is an open-source technology for definition and implementation of internet applications, which enforces a specification-oriented approach. Specification-oriented approach The specification-oriented approach is at the heart of XINS: first specifications need to be written; then documentation and code is generated from these specifications; then both testing and implementation can start. From specifications, XINS is able to generate: HTML documentation test forms SOAP-compliant WSDL a basic Java web application unit test code (in Java) stubs (in Java) client-side code (in Java) Components of the XINS technology Technically, XINS is composed of the following: An XML-based specification format for projects, APIs, functions, types and error codes A POX-style RPC protocol (called the XINS Standard Calling Convention), compatible with web browsers (HTTP parameters in, XML out). A tool for generating human-readable documentation, from the specifications. A tool for generating WSDL, from the specifications. A Log4J-based technology for logging (called Logdoc), offering a specification format, internationalization of log messages, generation of HTML documentation and generation of code. A Java library for calling XINS functions, the XINS/Java Client Framework; in xins-client.jar. A server-side container for Java-based XINS API implementations, the XINS/Java Server Framework; in xins-server.jar. This is like a servlet container for XINS APIs. A Java library with some common functionality, used by both the XINS/Java Client Framework and the XINS/Java Server Framework: the XINS/Java Common Library, in xins-common.jar. An introductory tutorial called the XINS Primer takes the reader by the hand with easy-to-follow steps to perform, with screenshots. Since version 1.3.0, the XINS/Java Server Framework supports not only POX-style calls, but also SOAP and XML-RPC. And it supports conversion using XSLT. As of version 2.
https://en.wikipedia.org/wiki/Audio%20tape%20specifications	Since the widespread adoption of reel-to-reel audio tape recording in the 1950s, audio tapes and tape cassettes have been available in many formats. This article describes the length, tape thickness and playing times of some of the most common ones. All tape thicknesses here refer to the total tape thickness unless otherwise specified, including the base, the oxide coating and any back coating. In the United States, tape thickness is often expressed as the thickness of the base alone. However, this varies from manufacturer to manufacturer and also between tape formulations from the same manufacturer. Outside of the US, the overall thickness is more often quoted, and is the more relevant measurement when relating the thickness to the length that can be fit onto a reel or into a cassette. Reel-to-reel quarter-inch The tape decks of the 1950s were mainly designed to use tape wide and to accept one of two reel formats: reels, almost always with metal flanges, which fit over a hub three inches in diameter. These reels and hubs were similar to those used for wider tape formats such as , , and tape widths, and were principally used for studio and other professional applications. The reels were known as NAB reels and the hubs on which they were mounted as NAB hubs. Reels of up to in diameter, most commonly with plastic flanges but metal was also used, which fit over a splined shaft known as a cine spindle, because it is of the same dimensions as the spindle used for Standard Standard 8mm cine film. These reels dominated domestic applications. The most common sizes were seven, five (12.7 cm) and three inches (7.6 cm) in diameter. In each case the shaft or hub had three splines. In machines designed to allow for vertical mounting, the upper part of the shaft or hub could commonly be rotated by 60° so the upper splines locked the reel in place (or, more recently, used a rubber stopper placed on the spindle). Some tape decks could accommodate either format by using
https://en.wikipedia.org/wiki/Blum%20axioms	In computational complexity theory the Blum axioms or Blum complexity axioms are axioms that specify desirable properties of complexity measures on the set of computable functions. The axioms were first defined by Manuel Blum in 1967. Importantly, Blum's speedup theorem and the Gap theorem hold for any complexity measure satisfying these axioms. The most well-known measures satisfying these axioms are those of time (i.e., running time) and space (i.e., memory usage). Definitions A Blum complexity measure is a pair with a numbering of the partial computable functions and a computable function which satisfies the following Blum axioms. We write for the i-th partial computable function under the Gödel numbering , and for the partial computable function . the domains of and are identical. the set is recursive. Examples is a complexity measure, if is either the time or the memory (or some suitable combination thereof) required for the computation coded by i. is not a complexity measure, since it fails the second axiom. Complexity classes For a total computable function complexity classes of computable functions can be defined as is the set of all computable functions with a complexity less than . is the set of all boolean-valued functions with a complexity less than . If we consider those functions as indicator functions on sets, can be thought of as a complexity class of sets. References Structural complexity theory Mathematical axioms
https://en.wikipedia.org/wiki/Skewb%20Diamond	The Skewb Diamond is an octahedron-shaped combination puzzle similar to the Rubik's Cube. It has 14 movable pieces which can be rearranged in a total of 138,240 possible combinations. This puzzle is the dual polyhedron of the Skewb. It was invented by Uwe Mèffert, a German puzzle inventor and designer. Description The Skewb Diamond has 6 octahedral corner pieces and 8 triangular face centers. All pieces can move relative to each other. It is a deep-cut puzzle; its planes of rotation bisect it. It is very closely related to the Skewb, and shares the same piece count and mechanism. However, the triangular "corners" present on the Skewb have no visible orientation on the Skewb Diamond, and the square "centers" gain a visible orientation on the Skewb Diamond. In other words, the corners on the Skewb are equivalent to the centers on the Skewb diamond. Combining pieces from the two can either give you an unscrambleable cuboctahedron or a compound of cube and octahedron with visible orientation on all pieces. Number of combinations The purpose of the puzzle is to scramble its colors, and then restore it to its original solved state. The puzzle has 6 corner pieces and 8 face centers. The positions of four of the face centers is completely determined by the positions of the other 4 face centers, and only even permutations of such positions are possible, so the number of arrangements of face centers is only 4!/2. Each face center has only a single orientation. Only even permutations of the corner pieces are possible, so the number of possible arrangements of corner pieces is 6!/2. Each corner has two possible orientations (it is not possible to change their orientation by 90° without disassembling the puzzle), but the orientation of the last corner is determined by the other 5. Hence, the number of possible corner orientations is 25. Hence, the number of possible combinations is: See also Skewb Ultimate External links Jaap's Skewb Diamond page Combination puzzles
https://en.wikipedia.org/wiki/Marquee%20%28structure%29	A marquee is most commonly a structure placed over the entrance to a hotel, theatre, casino, train station, or similar building. It often has signage stating either the name of the establishment or, in the case of theatres, the play or movie and the artist(s) appearing at that venue. The marquee is sometimes identifiable by a surrounding cache of light bulbs, usually yellow or white, that flash intermittently or as chasing lights. Etymology The current usage of the modern English word marquee, that in US English refers specifically to a canopy projecting over the main entrance of a theater, which displays details of the entertainment or performers, was documented in the academic journal American Speech in 1926: "Marquee, the front door or main entrance of the big top." In British English "marquee" refers more generally to a large tent, usually for social uses. The English word marquee is derived from the Middle French word marquise (the final /z/ probably being mistaken as -s plural), the feminine form corresponding to marquis ('nobleman'). The word marquise was also used to refer to various objects and fashions regarded as elegant or pleasing, hence: a kind of pear (1690), a canopy placed over a tent (1718), a type of settee (1770), a canopy in front of a building (1835), a ring with an elongated stone or setting, a diamond cut as a navette (late 19th century), and a style of woman's hat (1889). The oldest form of the word's root *merg- meant "boundary, border." Other words that descended from this Proto-Indo-European root include margin, margrave, and mark. Early examples of the modern use of marquee include 1931, The American Mercury: "Marquee, the canopy at the main entrance [of a circus]." 1933, Billboard, The marquee of the Rivoli, where Samarang is playing, reads: 'One of the most exciting films ever shown.' 1967, The Boston Globe: "British actors mean little on an American movie marquee and Sherlock Holmes always seems old-fashioned." History Movie m
https://en.wikipedia.org/wiki/Yang%E2%80%93Mills%20existence%20and%20mass%20gap	The Yang–Mills existence and mass gap problem is an unsolved problem in mathematical physics and mathematics, and one of the seven Millennium Prize Problems defined by the Clay Mathematics Institute, which has offered a prize of US$1,000,000 for its solution. The problem is phrased as follows: Yang–Mills Existence and Mass Gap. Prove that for any compact simple gauge group G, a non-trivial quantum Yang–Mills theory exists on and has a mass gap Δ > 0. Existence includes establishing axiomatic properties at least as strong as those cited in , and . In this statement, a quantum Yang–Mills theory is a non-abelian quantum field theory similar to that underlying the Standard Model of particle physics; is Euclidean 4-space; the mass gap Δ is the mass of the least massive particle predicted by the theory. Therefore, the winner must prove that: Yang–Mills theory exists and satisfies the standard of rigor that characterizes contemporary mathematical physics, in particular constructive quantum field theory, and The mass of all particles of the force field predicted by the theory are strictly positive. For example, in the case of G=SU(3)—the strong nuclear interaction—the winner must prove that glueballs have a lower mass bound, and thus cannot be arbitrarily light. The general problem of determining the presence of a spectral gap in a system is known to be undecidable. Background The problem requires the construction of a QFT satisfying the Wightman axioms and showing the existence of a mass gap. Both of these topics are described in sections below. The Wightman axioms The Millennium problem requires the proposed Yang–Mills theory to satisfy the Wightman axioms or similarly stringent axioms. There are four axioms: W0 (assumptions of relativistic quantum mechanics) Quantum mechanics is described according to von Neumann; in particular, the pure states are given by the rays, i.e. the one-dimensional subspaces, of some separable complex Hilbert space. The Wight
https://en.wikipedia.org/wiki/Algebraic%20space	In mathematics, algebraic spaces form a generalization of the schemes of algebraic geometry, introduced by Michael Artin for use in deformation theory. Intuitively, schemes are given by gluing together affine schemes using the Zariski topology, while algebraic spaces are given by gluing together affine schemes using the finer étale topology. Alternatively one can think of schemes as being locally isomorphic to affine schemes in the Zariski topology, while algebraic spaces are locally isomorphic to affine schemes in the étale topology. The resulting category of algebraic spaces extends the category of schemes and allows one to carry out several natural constructions that are used in the construction of moduli spaces but are not always possible in the smaller category of schemes, such as taking the quotient of a free action by a finite group (cf. the Keel–Mori theorem). Definition There are two common ways to define algebraic spaces: they can be defined as either quotients of schemes by etale equivalence relations, or as sheaves on a big etale site that are locally isomorphic to schemes. These two definitions are essentially equivalent. Algebraic spaces as quotients of schemes An algebraic space X comprises a scheme U and a closed subscheme R ⊂ U × U satisfying the following two conditions: 1. R is an equivalence relation as a subset of U × U 2. The projections pi: R → U onto each factor are étale maps. Some authors, such as Knutson, add an extra condition that an algebraic space has to be quasi-separated, meaning that the diagonal map is quasi-compact. One can always assume that R and U are affine schemes. Doing so means that the theory of algebraic spaces is not dependent on the full theory of schemes, and can indeed be used as a (more general) replacement of that theory. If R is the trivial equivalence relation over each connected component of U (i.e. for all x, y belonging to the same connected component of U, we have xRy if and only if x=y), then the al
https://en.wikipedia.org/wiki/Mex%20%28mathematics%29	In mathematics, the mex ("minimum excluded value") of a subset of a well-ordered set is the smallest value from the whole set that does not belong to the subset. That is, it is the minimum value of the complement set. Beyond sets, subclasses of well-ordered classes have minimum excluded values. Minimum excluded values of subclasses of the ordinal numbers are used in combinatorial game theory to assign nim-values to impartial games. According to the Sprague–Grundy theorem, the nim-value of a game position is the minimum excluded value of the class of values of the positions that can be reached in a single move from the given position. Minimum excluded values are also used in graph theory, in greedy coloring algorithms. These algorithms typically choose an ordering of the vertices of a graph and choose a numbering of the available vertex colors. They then consider the vertices in order, for each vertex choosing its color to be the minimum excluded value of the set of colors already assigned to its neighbors. Examples The following examples all assume that the given set is a subset of the class of ordinal numbers: where is the limit ordinal for the natural numbers. Game theory In the Sprague–Grundy theory the minimum excluded ordinal is used to determine the nimber of a normal-play impartial game. In such a game, either player has the same moves in each position and the last player to move wins. The nimber is equal to 0 for a game that is lost immediately by the first player, and is equal to the mex of the nimbers of all possible next positions for any other game. For example, in a one-pile version of Nim, the game starts with a pile of stones, and the player to move may take any positive number of stones. If is zero stones, the nimber is 0 because the mex of the empty set of legal moves is the nimber 0. If is 1 stone, the player to move will leave 0 stones, and , gives the nimber for this case. If is 2 stones, the player to move can leave 0 or 1 sto
https://en.wikipedia.org/wiki/Synovial%20osteochondromatosis	Synovial osteochondromatosis (SOC) (synonyms include synovial chondromatosis, primary synovial chondromatosis, synovial chondrometaplasia) is a rare disease that creates a benign change or proliferation in the synovium or joint-lining tissue, which changes to form bone-forming cartilage. In most occurrences, there is only one joint affected, either the knee, the hip, or the elbow. Rarely involves the TMJ. The cause is unknown. In this condition, cartilaginous metaplasia takes place within the synovial membrane of the joint. Metaplastic synovium organizes into nodules. With minor trauma, nodules are shed as small bodies into the joint space. In some patients, the disease process may involve tendon sheaths and bursal sacs. Cartilaginous intra-articular bodies float freely within the synovial fluid, which they require for nutrition and growth. Progressive enlargement and ossification occur with time. If they remain free, they continue to grow larger and more calcified. In severe cases, they may occupy the entire joint space or penetrate to adjacent tissues. Also, they can deposit in the synovial lining, reestablish a blood supply, and become replaced by bone. On occasion, synovial reattachment can lead to complete reabsorption of the cartilage fragment. Signs and symptoms Chronic, progressive pain and swelling of the affected joint are exacerbated by physical activity. Joint effusion and limited range of motion are common associated features. It affects primarily large joints, including knee (>50% of cases), elbow, hip, and shoulder. SOC is twice as common in men as women. Some patients have intra-articular bodies resting in stable positions within joint recesses or bursae. These patients may be asymptomatic, with SOC merely as an incidental finding at imaging. Complications Malignant transformation to synovial chondrosarcoma. This is a very rare complication occurring in chronic cases. Treatment entails synovial excision and total joint replacemen
https://en.wikipedia.org/wiki/Shared%20Whois%20Project	The Shared Whois Project (SWIP) is the process used to submit, maintain and update information to ensure up-to-date and efficient maintenance of WHOIS records, as structured in RFC 1491. The process updates WHOIS to contain information regarding what organization is using a specific IP address, or a specific block of addresses. Additionally, it provides means to track the use of an organization's current allocations of IP addresses, so that additional allocation of IP addresses may be justified and usage reports or case studies may be done. SWIP must be used within seven days of any reassignment of an IP address space to a downstream customer to: Provide new reassignments of blocks of eight or more IP addresses Delete existing reassignments, or Modify data connected to existing reassignments. In contrast, an organization is not required to submit a SWIP template for fewer than eight IP addresses. Allocations, assignments or reassignments of blocks of 8,192 addresses and more (greater than a /19 block) must be approved by ARIN beforehand. Companies assigned a block of 65,536 addresses or more will be responsible for maintaining all IN-ADDR.ARPA domain records for their customers. There are two types of registration. The first is an allocation, for blocks of IP addresses which will later be reallocated or reassigned to third parties. The second is an assignment, for blocks that will not be reassigned, or the recipient is an end-user. References Bibliography External links ARIN's Reporting Reassignments Internet protocols Internet Standards
https://en.wikipedia.org/wiki/STONITH	STONITH ("Shoot The Other Node In The Head" or "Shoot The Offending Node In The Head"), sometimes called STOMITH ("Shoot The Other Member/Machine In The Head"), is a technique for fencing in computer clusters. Fencing is the isolation of a failed node so that it does not cause disruption to a computer cluster. As its name suggests, STONITH fences failed nodes by resetting or powering down the failed node. Multi-node error-prone contention in a cluster can have catastrophic results, such as if both nodes try writing to a shared storage resource. STONITH provides effective, if rather drastic, protection against these problems. Single node systems use a comparable mechanism called a watchdog timer. A watchdog timer will reset the node if the node does not tell the watchdog circuit that it is operating well. A STONITH decision can be based on various decisions which can be customer specific plugins. Google's inclusive language developer documentation discourages usage of this term. References External links Definition from the Linux-HA Project STONITH Deathmatch Explained (and Some Hints for Resource Agent Authors and Systems Engineers) Cluster computing
https://en.wikipedia.org/wiki/OpenBSM	OpenBSM is an open source implementation of Sun's Basic Security Module (BSM) Audit API and file format. BSM, which is a system used for auditing, describes a set of system call and library interfaces for managing audit records as well as a token stream file format that permits extensible and generalized audit trail processing. OpenBSM includes system include files appropriate for inclusion in an operating system implementation of Audit, libbsm, an implementation of the BSM library interfaces for generating, parsing, and managing audit records, auditreduce and praudit, audit reduction and printing tools, API documentation, and sample configuration files. Works in progress include extensions to the libbsm API to support easier audit trail analysis, including a pattern matching library. OpenBSM is derived from the BSM audit implementation found in Apple's open source Darwin operating system, which upon request, Apple relicensed under a BSD licence to allow for integration into FreeBSD and other systems. The Darwin BSM implementation was created by McAfee Research under contract to Apple, and has since been extensively extended by the volunteer TrustedBSD team. OpenBSM is included in FreeBSD as of version 6.2 and later, and has been announced as a Mac OS X Snow Leopard feature. External links TrustedBSD: OpenBSM FreeBSD Handbook: Security Event Auditing Apple Computer: Common Criteria BSD software Operating system security Software using the BSD license
https://en.wikipedia.org/wiki/Puzz%203D	Puzz 3D is the brand name of three-dimensional jigsaw puzzles, manufactured by Hasbro and formerly by Wrebbit, Inc. Unlike traditional puzzles which are composed of series of flat pieces that when put together, create a single unified image, the Puzz 3D series of puzzles are composed on plastic foam, with part of an image graphed on a stiff paper facade glued to the underlying foam piece and cut to match the piece's dimensions. When the pieces are put together, they create a standing structure. History Puzz 3D puzzles, invented by Paul Gallant, were first made in 1991 under the Quebec-based company Wrebbit. Throughout the 1990s, three-dimensional puzzles were made, leading to a rapid growth in the company. In 1993, Hasbro's Milton Bradley Company bought Wrebbit's Puzz 3D Line, and in 2005 Hasbro themselves completely bought Wrebbit, in 2006, moved the manufacture of Wrebbit's puzzles to its East Longmeadow, Massachusetts facility. The last series made under Hasbro was Towers Made to Scale. The series consisted of 13 skyscrapers from around the world. All of the structures were made to be at 1:585 scale, and all of the towers glowed in the dark. By 2006, all of the Puzz 3D puzzles had been discontinued, but in 2011, the Puzz 3D line was revitalized by Winning Solutions, Inc. Winning Solutions first released the Eiffel Tower and Empire State Building, and released a model of Anif Palace in 2012. As of 2014, Hasbro has brought some of the old Puzz 3D line back into production (made in China) in the same boxes. A separate company Wrebbit3D, making new products along with some of the old line, has been created by some of the old Wrebbit staff. Puzzles Typically, the structures released were famous landmarks, including the White House, Big Ben, CN Tower, and the Neuschwanstein castle. In addition to this, Puzz 3D has also released science-fiction themed puzzles, such as the Millennium Falcon spacecraft from the Star Wars franchise, and structures from legends suc
https://en.wikipedia.org/wiki/Noddy%20%28camera%29	Noddy was a camera system used for generating idents for the BBC One and BBC Two television channels from late 1963 to February 1985. The Noddy video camera was controlled by a servomotor to pan and tilt (or 'nod', hence the name Noddy) across a set of pre-arranged physical objects; captions and mechanical models. The camera was black-and-white, with colour electronically added to its output. This system eliminated the delay associated with swapping graphics upon a conventional copy stand. It also allowed for the depth required by mechanical objects such as clocks and a rotating globe. History The BBC first employed the system in the 1960s, before the advent of colour. The system's remote operation allowed the operator to control it with ease, and allowed the idents to be of no fixed length as the clock symbols could continue for many minutes at a time. A smaller black and white camera was introduced as camera technology progressed and, from 1969, a process was introduced to add colour signals to the camera output. This electronic addition of colour was convenient and made the networks' rebrands easy to perform. BBC One mirrored globes The most famous idents of the Noddy system were the BBC One mirrored globes used between 1969 and 1985, albeit with minor colour changes. The system consisted of an internally lit, rotating globe in front of a concave mirror. The oceans were painted onto the globe in metallic black paint, leaving the land masses as unpainted patches. The original globe ident introduced on 15 November 1969 featured blue continents and logo against a black background. The logo included the word 'COLOUR' after the BBC One (then BBC 1) corporate logo, to identify the new programme format and act as an advertisement to the vast majority of viewers who were still watching in black and white (as the colour version of the television licence, which financed the BBC, was much more expensive). Full colour broadcasts across the UK did not become available unti
https://en.wikipedia.org/wiki/Linux%20adoption	Linux adoption is the adoption of Linux computer operating systems (OS) by households, nonprofit organizations, businesses, and governments. Many factors have resulted in the expanded use of Linux systems by traditional desktop users as well as operators of server systems, including the desire to minimize software costs, increase network security and support for open-source philosophical principles. In recent years several governments, at various levels, have enacted policies shifting state-owned computers to Linux from proprietary software regimes. In August 2010, Jeffrey Hammond, principal analyst at Forrester Research, declared, "Linux has crossed the chasm to mainstream adoption," a statement attested by the large number of enterprises that had transitioned to Linux during the late-2000s recession. In a company survey completed in the third quarter of 2009, 48% of surveyed companies reported using an open-source operating system. The Linux Foundation regularly releases publications regarding the Linux kernel, Linux OS distributions, and related themes. One such publication, "Linux Adoption Trends: A Survey of Enterprise End Users," is freely available upon registration. Traditionally, the term Linux adoption refers to adoption of a Linux OS made for "desktop" computers, the original intended use (or adoption on servers, that is essentially the same form of OS). Adoption of that form on personal computers is still low relatively, while adoption of the Android operating system is very high. The term Linux adoption, often overlooks that operating system or other uses such as in ChromeOS that also use the Linux kernel (but have almost nothing else in common, not even the name – Linux – usually applied; while Android is the most popular variant – in fact the most popular operating system in the world). Linux adopters Outside of traditional web services, Linux powers many of the biggest Internet properties (e.g., Google, Amazon, Facebook, eBay, Twitter or Yahoo!
https://en.wikipedia.org/wiki/Karush%E2%80%93Kuhn%E2%80%93Tucker%20conditions	In mathematical optimization, the Karush–Kuhn–Tucker (KKT) conditions, also known as the Kuhn–Tucker conditions, are first derivative tests (sometimes called first-order necessary conditions) for a solution in nonlinear programming to be optimal, provided that some regularity conditions are satisfied. Allowing inequality constraints, the KKT approach to nonlinear programming generalizes the method of Lagrange multipliers, which allows only equality constraints. Similar to the Lagrange approach, the constrained maximization (minimization) problem is rewritten as a Lagrange function whose optimal point is a (global) saddle point, i.e. a global maximum (minimum) over the domain of the choice variables and a global minimum (maximum) over the multipliers, which is why the Karush–Kuhn–Tucker theorem is sometimes referred to as the saddle-point theorem. The KKT conditions were originally named after Harold W. Kuhn and Albert W. Tucker, who first published the conditions in 1951. Later scholars discovered that the necessary conditions for this problem had been stated by William Karush in his master's thesis in 1939. Nonlinear optimization problem Consider the following nonlinear optimization problem in standard form: minimize subject to where is the optimization variable chosen from a convex subset of , is the objective or utility function, are the inequality constraint functions and are the equality constraint functions. The numbers of inequalities and equalities are denoted by and respectively. Corresponding to the constrained optimization problem one can form the Lagrangian function where The Karush–Kuhn–Tucker theorem then states the following. Since the idea of this approach is to find a supporting hyperplane on the feasible set , the proof of the Karush–Kuhn–Tucker theorem makes use of the hyperplane separation theorem. The system of equations and inequalities corresponding to the KKT conditions is usually not solved directly, except in the few sp
https://en.wikipedia.org/wiki/Tiling%20puzzle	Tiling puzzles are puzzles involving two-dimensional packing problems in which a number of flat shapes have to be assembled into a larger given shape without overlaps (and often without gaps). Some tiling puzzles ask you to dissect a given shape first and then rearrange the pieces into another shape. Other tiling puzzles ask you to dissect a given shape while fulfilling certain conditions. The two latter types of tiling puzzles are also called dissection puzzles. Tiling puzzles may be made from wood, metal, cardboard, plastic or any other sheet-material. Many tiling puzzles are now available as computer games. Tiling puzzles have a long history. Some of the oldest and most famous are jigsaw puzzles and the tangram puzzle. Other examples of tiling puzzles include: Conway puzzle Domino tiling, of which the mutilated chessboard problem is one example Eternity puzzle Geometric magic square Puzz-3D Squaring the square Tantrix T puzzle Many three-dimensional mechanical puzzles can be regarded as three-dimensional tiling puzzles. See also Dissection puzzle Polyforms Sliding puzzle Tessellation Wang tile Tessellation
https://en.wikipedia.org/wiki/Sliding%20puzzle	A sliding puzzle, sliding block puzzle, or sliding tile puzzle is a combination puzzle that challenges a player to slide (frequently flat) pieces along certain routes (usually on a board) to establish a certain end-configuration. The pieces to be moved may consist of simple shapes, or they may be imprinted with colours, patterns, sections of a larger picture (like a jigsaw puzzle), numbers, or letters. Sliding puzzles are essentially two-dimensional in nature, even if the sliding is facilitated by mechanically interlinked pieces (like partially encaged marbles) or three-dimensional tokens. In manufactured wood and plastic products, the linking and encaging is often achieved in combination, through mortise-and-tenon key channels along the edges of the pieces. In at least one vintage case of the popular Chinese cognate game Huarong Road, a wire screen prevents lifting of the pieces, which remain loose. As the illustration shows, some sliding puzzles are mechanical puzzles. However, the mechanical fixtures are usually not essential to these puzzles; the parts could as well be tokens on a flat board that are moved according to certain rules. Unlike tour puzzles, a sliding block puzzle prohibits lifting any piece off the board. This property separates sliding puzzles from rearrangement puzzles. Hence, finding moves and the paths opened up by each move within the two-dimensional confines of the board are important parts of solving sliding block puzzles. The oldest type of sliding puzzle is the fifteen puzzle, invented by Noyes Chapman in 1880; Sam Loyd is often wrongly credited with making sliding puzzles popular based on his false claim that he invented the fifteen puzzle. Chapman's invention initiated a puzzle craze in the early 1880s. From the 1950s through the 1980s sliding puzzles employing letters to form words were very popular. These sorts of puzzles have several possible solutions, as may be seen from examples such as Ro-Let (a letter-based fifteen puzzle),
https://en.wikipedia.org/wiki/Puzzle%20lock	A puzzle lock or puzzle padlock is a type of mechanical puzzle. It consists of a lock with unusual or hidden mechanics. Puzzle locks are reconfigurable mechanisms where the topological structure changes during the operation. Such locks are sometimes called trick locks, because there is a trick to opening them which needs to be found. Puzzle locks exist both with keys and without keys. China Puzzle locks with exposed keyholes were widely used in ancient China and can be very tricky to open. There are three main types in China: Locks with extra obstacle Locks with indirect insertion Multi-stage locks. Europe In Europe, many small puzzle padlocks had front plate with a face or mask. The padlocks were designed to secure small bags or pouches and could be found across Europe with the most around the Danubian provinces and Aquileia. They were often shaped like rings and may have been fitted around the mouth of a bag as a sort of tamper-proof seal. The earliest Roman puzzle locks date back to the 2nd century BCE. In the 1850s in the UK, "puzzle lock" was synonymous with "letter lock" and used to denote a lettered combination lock. See also Puzzle box References Mechanical puzzles Locksmithing
https://en.wikipedia.org/wiki/Digital%20cassettes	Digital audio cassette formats introduced to the professional audio and consumer markets: Digital Audio Tape (or DAT) is the most well-known, and had some success as an audio storage format among professionals and "prosumers" before the prices of hard drive and solid-state flash memory-based digital recording devices dropped in the late 1990s. Hard-drive recording has mostly made DAT obsolete, as hard disk recorders offer more editing versatility than tape, and easier importation into digital audio workstations (DAWs) and non-linear video editing (NLE) systems. Digital Compact Cassette was intended as a digital replacement for the mass-market analog cassette tape, but received very little attention or adaptation. Its failure is generally attributed to higher production costs than audio CDs, durability and lukewarm reception by consumers. Digital videocassettes include: Betacam IMX (Sony) D-VHS (JVC) D1 (Sony) D2 (Sony) D3 D5 HD Digital-S D9 (JVC) Digital Betacam (Sony) Digital8 (Sony) DV HDV ProHD (JVC) MiniDV MicroMV Analog cassettes used as digital data storage: Historically, the compact audio cassette which was originally designed for analog storage of music was used as an alternative to disk drives in the late 1970s and early 1980s to provide data storage for home computers. The ADAT system uses Super VHS tapes to record 8 synchronized digital audiotracks at once. There have also been several audio recording systems which used VHS video recorders as storage devices and video tape transports, generally by encoding the digital data to be recorded into an analog composite video signal (which resembles static) and then recording this to magnetic tape. These systems were generally used as "mixdown" recorders, to record the finished mix from a multi-track recorder in preparation for the manufacture of a vinyl record, cassette tape, or CD. An example was the Dbx Model 700. Several companies sold VHS backup solutions in the 80s and 90s where data was c
https://en.wikipedia.org/wiki/Univariate	In mathematics, a univariate object is an expression, equation, function or polynomial involving only one variable. Objects involving more than one variable are multivariate. In some cases the distinction between the univariate and multivariate cases is fundamental; for example, the fundamental theorem of algebra and Euclid's algorithm for polynomials are fundamental properties of univariate polynomials that cannot be generalized to multivariate polynomials. In statistics, a univariate distribution characterizes one variable, although it can be applied in other ways as well. For example, univariate data are composed of a single scalar component. In time series analysis, the whole time series is the "variable": a univariate time series is the series of values over time of a single quantity. Correspondingly, a "multivariate time series" characterizes the changing values over time of several quantities. In some cases, the terminology is ambiguous, since the values within a univariate time series may be treated using certain types of multivariate statistical analyses and may be represented using multivariate distributions. In addition to the question of scaling, a criterion (variable) in univariate statistics can be described by two important measures (also key figures or parameters): Location & Variation. Measures of Location Scales (e.g. mode, median, arithmetic mean) describe in which area the data is arranged centrally. Measures of Variation (e.g. span, interquartile distance, standard deviation) describe how similar or different the data are scattered. See also Arity Bivariate (disambiguation) Multivariate (disambiguation) Univariate analysis Univariate binary model Univariate distribution References Mathematical terminology Theory of probability distributions
https://en.wikipedia.org/wiki/Lean%20government	Lean government refers to the application of Lean Manufacturing (also known as "Lean") principles and methods to both identify and then implement the most efficient, value added way to provide government services. Government agencies have found that when Lean is implemented, they see an improved understanding of how their own processes work, that it facilitates the quick identification and implementation of improvements and that it builds a culture of continuous improvement. Lean for government focuses on governing and serving citizens with respect and continuously improving service delivery by cutting out "waste" and "inefficiency" in processes; this in turn will result in better services overall, engaged civil servants as well as more value for tax-supported programs and services. Generally, proponents also see that a lean government is a means to expand the capacity of government to provide more services per unit of investment. Common methods and approaches Many lean manufacturing methods have been successfully adapted to identify non-value added activities (waste) in administrative, transactional, and office processes that are common in government agencies. Common Lean methods include: Value Stream Mapping (VSM) – Value stream mapping refers to the development of a high-level visual representation of a process flow that is involved in delivering a product or service (called a "value stream") to customers. VSM events, which are typically 3–4 days, focus on identifying the sources of non-value added activity and prioritizing possible improvement activities. Kaizen – Kaizen means to change for the good of all and is based on the philosophy of improvement, without regard to its size, type or duration. Kaizen activity is often focused on rapid process improvement events (called kaizen events) that bring together a cross-functional team for 3–5 days to study a specific process followed by implementing process changes. 5S – 5S is the name of a workplace organizat
https://en.wikipedia.org/wiki/Numbering%20%28computability%20theory%29	In computability theory a numbering is the assignment of natural numbers to a set of objects such as functions, rational numbers, graphs, or words in some formal language. A numbering can be used to transfer the idea of computability and related concepts, which are originally defined on the natural numbers using computable functions, to these different types of objects. Common examples of numberings include Gödel numberings in first-order logic, the description numbers that arise from universal Turing machines and admissible numberings of the set of partial computable functions. Definition and examples A numbering of a set is a surjective partial function from to S (Ershov 1999:477). The value of a numbering ν at a number i (if defined) is often written νi instead of the usual . Examples of numberings include: The set of all finite subsets of has a numbering , defined so that and so that, for each finite nonempty set , where (Ershov 1999:477). This numbering is a (partial) bijection. A fixed Gödel numbering of the computable partial functions can be used to define a numbering W of the recursively enumerable sets, by letting by W(i) be the domain of φi. This numbering will be surjective (like all numberings) but not injective: there will be distinct numbers that map to the same recursively enumerable set under W. Types of numberings A numbering is total if it is a total function. If the domain of a partial numbering is recursively enumerable then there always exists an equivalent total numbering (equivalence of numberings is defined below). A numbering η is decidable if the set is a decidable set. A numbering η is single-valued if η(x) = η(y) if and only if x=y; in other words if η is an injective function. A single-valued numbering of the set of partial computable functions is called a Friedberg numbering. Comparison of numberings There is a preorder on the set of all numberings. Let and be two numberings. Then is reducible to , written
https://en.wikipedia.org/wiki/Second-order%20cellular%20automaton	A second-order cellular automaton is a type of reversible cellular automaton (CA) invented by Edward Fredkin where the state of a cell at time depends not only on its neighborhood at time , but also on its state at time . General technique In general, the evolution rule for a second-order automaton may be described as a function that maps the neighborhood of a cell to a permutation on the states of the automaton. In each time step , for each cell of the automaton, this function is applied to the neighborhood of to give a permutation . Then, this permutation is applied to the state of cell at time , and the result is the state of the cell at time . In this way, the configuration of the automaton at each time step is computed from two previous time steps: the immediately previous step determines the permutations that are applied to the cells, and the time step before that one gives the states on which these permutations operate. The reversed time dynamics of a second-order automaton may be described by another second-order automaton with the same neighborhood, in which the function mapping neighborhoods to permutations gives the inverse permutation to . That is, on each possible neighborhood , and should be inverse permutations. With this reverse rule, the automaton described by function correctly computes the configuration at time from the configurations at time and . Because every second-order automaton can be reversed in this way, it follows that they are all reversible cellular automata, regardless of which function is chosen to determine the automaton rule. For two-state automata If a cellular automaton has only two states, then there are also only two possible permutations of states: the identity permutation that maps each state to itself, and the permutation that maps each state to the other state. We may identify these two permutations with the two states of the automaton. In this way, every second-order cellular automaton (defined by a functi
https://en.wikipedia.org/wiki/Block%20cellular%20automaton	A block cellular automaton or partitioning cellular automaton is a special kind of cellular automaton in which the lattice of cells is divided into non-overlapping blocks (with different partitions at different time steps) and the transition rule is applied to a whole block at a time rather than a single cell. Block cellular automata are useful for simulations of physical quantities, because it is straightforward to choose transition rules that obey physical constraints such as reversibility and conservation laws. Definition A block cellular automaton consists of the following components: A regular lattice of cells A finite set of the states that each cell may be in A partition of the cells into a uniform tessellation in which each tile of the partition has the same size and shape A rule for shifting the partition after each time step A transition rule, a function that takes as input an assignment of states for the cells in a single tile and produces as output another assignment of states for the same cells. In each time step, the transition rule is applied simultaneously and synchronously to all of the tiles in the partition. Then, the partition is shifted and the same operation is repeated in the next time step, and so forth. In this way, as with any cellular automaton, the pattern of cell states changes over time to perform some nontrivial computation or simulation. Neighborhoods The simplest partitioning scheme is probably the Margolus neighborhood, named after Norman Margolus, who first studied block cellular automata using this neighborhood structure. In the Margolus neighborhood, the lattice is divided into -cell blocks (or squares in two dimensions, or cubes in three dimensions, etc.) which are shifted by one cell (along each dimension) on alternate timesteps. A closely related technique due to K. Morita and M. Harao consists in partitioning each cell into a finite number of parts, each part being devoted to some neighbor. The evolution proceeds by exch
https://en.wikipedia.org/wiki/Comparison%20of%20time-tracking%20software	This is a comparison of notable time-tracking software packages and web hosted services. See also Deployment management Flextime plan Project management software Timesheet Working time References Administrative software Lists of software Software comparisons
https://en.wikipedia.org/wiki/Gunfright	Gunfright is an action-adventure game developed by Ultimate Play the Game and published by U.S. Gold. It was first released for the ZX Spectrum in December 1985, then released for Amstrad CPC and the MSX the following year. The player takes the role of a sheriff in the town of Black Rock and is tasked with eliminating outlaws who are scattered throughout the settlement. The game was developed directly after Nightshade, and re-uses the latter game's Filmation II game engine that allows images to be rendered without overlapping each other. The game received mostly positive reviews upon release; praise was directed at the graphics and presentation, but criticism was directed at the game's similarity to Nightshade. It was later included in Rare Replay, Rare's 2015 Xbox One retrospective compilation. Gameplay The game is presented in an isometric format and set in the fictional town of Black Rock. The player takes on the role of Sheriff Quickdraw, whose main objective is to track down and kill a gang of outlaws who are hiding in the town. The game begins with a first-person perspective targeting minigame in which vertically scrolling bags of money can be shot at using crosshairs. Shooting the bags give the player initial sums of money which can be used to purchase ammunition. Sheriff Quickdraw must locate the wanted outlaws one by one. Once an outlaw has been found and shot to initiate a duel, the game shifts to the first-person targeting minigame. This time, the player must shoot the rapidly moving outlaw as quickly as possible. The player can either wait for the outlaw to draw, or take the initiative and shoot first, which will make the bandit draw his weapon as well. If the player successfully shoots an outlaw, a bounty is paid (increasing with every round), and a new outlaw enters the town. Players encounter helpful residents who will point the way to outlaws. The residents need to be protected during gameplay, as the player has to pay a fine if any are shot by
https://en.wikipedia.org/wiki/Core%20Data	Core Data is an object graph and persistence framework provided by Apple in the macOS and iOS operating systems. It was introduced in Mac OS X 10.4 Tiger and iOS with iPhone SDK 3.0. It allows data organized by the relational entity–attribute model to be serialized into XML, binary, or SQLite stores. The data can be manipulated using higher level objects representing entities and their relationships. Core Data manages the serialized version, providing object lifecycle and object graph management, including persistence. Core Data interfaces directly with SQLite, insulating the developer from the underlying SQL. Just as Cocoa Bindings handle many of the duties of the controller in a model–view–controller design, Core Data handles many of the duties of the data model. Among other tasks, it handles change management, serializing to disk, memory footprint minimization and queries against the data. Usage Core Data describes data with a high level data model expressed in terms of entities and their relationships plus fetch requests that retrieve entities meeting specific criteria. Code can retrieve and manipulate this data on a purely object level without having to worry about the details of storage and retrieval. The controller objects available in Interface Builder can retrieve and manipulate these entities directly. When combined with Cocoa bindings the UI can display many components of the data model without needing background code. For example: a developer might be writing a program to handle vCards. In order to manage these, the author intends to read the vCards into objects, and then store them in a single larger XML file. Using Core Data the developer would drag their schema from the data designer in Xcode into an interface builder window to create a GUI for their schema. They could then write standard Objective-C or Swift code to read vCard files and put the data into Core Data managed entities. From that point on the author's code manipulates these Core Data o
https://en.wikipedia.org/wiki/Minibar	A minibar is a small refrigerator, typically an absorption refrigerator, in a hotel room or cruise ship stateroom. The hotel staff fill it with drinks and snacks for the guest to purchase during their stay. It is stocked with a precise inventory of goods, with a price list. The guest is charged for goods consumed when checking out of the hotel. Some newer minibars use infrared or other automated methods of recording purchases. These detect the removal of an item, and charge the guest's credit card right away, even if the item is not consumed. This is done to prevent loss of product, theft and lost revenue. The minibar is commonly stocked with small bottles of alcoholic beverages, juice, bottled water, and soft drinks. There may also be candy, cookies, crackers, and other small snacks. Prices are generally very high compared to similar items purchased from a store, because the guest is paying for the convenience of immediate access and also the upkeep of the bar. Prices vary, but it is common for one can of non-alcoholic beverage to cost $6–10 USD. Due to the convenience of room service and the minibar, prices charged to the patron are much higher than the hotel's restaurant or tuck shop. As premium bottled water has become popular with guests since the 2000s, there is "ambient placement" of such chargeable products outside the minibar and in the guests' line of vision; for example "by placing [bottled] water on bedside tables, during the night, people are more likely to grab it than get up to get a glass of water". The world's first minibar was introduced at the Hong Kong Hilton Hotel by manager Robert Arnold in 1974. In the months following its introduction in-room drink sales increased 500%, and the Hong Kong Hilton's overall annual revenue was boosted by 5%. The following year the Hilton group rolled out the minibar concept across all its hotels. In recent years, as minibars become less and less popular with guests, hotels have been eliminating this feature f
https://en.wikipedia.org/wiki/Kibu.com	Kibu.com was an American website for teenage girls that was created in 1999 and launched in 2000. The website was founded as an online community for girls to discuss and exchange advice. Kibu.com secured a US$22 million investment from high-profile figures in the tech industry, including Jim Clark. However, following the dot-com bubble burst, Kibu.com shut down on October 2, 2000, in only 46 days after launch. The company's leaders disclosed that the decision to shut down Kibu.com was made because of concerns in securing revenue in the future. History Kibu.com was created in April 1999 as an online community for teenage girls. The name "Kibu" was derived from the Japanese word for "foundation" (). Judy Macdonald, the founder of the art CD-ROM PrintPak, was brought into staff as its CEO in September 1999. Molly Lynch, a former employee of @Home Network was also added as a staff member. In February 2000, Kibu.com received an investment of US$22 million from high-profile figures in Silicon Valley, such as Netscape co-founder Jim Clark, former @Home Network chairman Tom Jermoluk, the venture capital firm Kleiner Perkins Caufield & Byers, and CNET chairman Shelby Bonnie. Unlike other websites struggling from the dot-com bubble burst, the investors believed Kibu.com had the advantage in its demographic, as there had been a growth in teenage users online. Kibu.com predicted the investment would sustain the website up to Q2 2001 and hoped to make a profit by late 2001, with plans to have their own branded retail products and its own center in Ghirardelli Square located in San Francisco, California. In addition, ChickClick founder Heidi Swanson and her sister, Heather, were hired to work on the website. Kibu.com went online on May 1, 2000. The website ran on revenue from sponsorship deals with Skechers, Barnes & Noble, and The Princeton Review, as well as attracting advertisements from Kmart. Unlike other websites, which used banner ads, Kibu.com offered product samples
https://en.wikipedia.org/wiki/Angle%20bisector%20theorem	In geometry, the angle bisector theorem is concerned with the relative lengths of the two segments that a triangle's side is divided into by a line that bisects the opposite angle. It equates their relative lengths to the relative lengths of the other two sides of the triangle. Theorem Consider a triangle . Let the angle bisector of angle intersect side at a point between and . The angle bisector theorem states that the ratio of the length of the line segment to the length of segment is equal to the ratio of the length of side to the length of side : and conversely, if a point on the side of divides in the same ratio as the sides and , then is the angle bisector of angle . The generalized angle bisector theorem states that if lies on the line , then This reduces to the previous version if is the bisector of . When is external to the segment , directed line segments and directed angles must be used in the calculation. The angle bisector theorem is commonly used when the angle bisectors and side lengths are known. It can be used in a calculation or in a proof. An immediate consequence of the theorem is that the angle bisector of the vertex angle of an isosceles triangle will also bisect the opposite side. Proofs There exist many different ways of proving the angle bisector theorem. A few of them are shown below. Proof using similar triangles As shown in the accompanying animation, the theorem can be proved using similar triangles. In the version illustrated here, the triangle gets reflected across a line that is perpendicular to the angle bisector , resulting in the triangle with bisector . The fact that the bisection-produced angles and are equal means that and are straight lines. This allows the construction of triangle that is similar to . Because the ratios between corresponding sides of similar triangles are all equal, it follows that . However, was constructed as a reflection of the line , and so those two lines are of equal le
https://en.wikipedia.org/wiki/Static%20build	A static build is a compiled version of a program which has been statically linked against libraries. Linking In computer science, linking means taking one or more objects generated by compilers and assembling them into a single executable program. The objects are program modules containing machine code and symbol definitions, which come in two varieties: Defined or exported symbols are functions or variables that are present in the module represented by the object, and which should be available for use by other modules. Undefined or imported symbols are functions or variables that are called or referenced by this object, but not internally defined. A linker program then resolves references to undefined symbols by finding out which other object defines a symbol in question, and replacing placeholders with the symbol's address. Linkers can take objects from a collection called a library. The final program does not include the whole library, only those objects from it that are needed. Libraries for diverse purposes exist, and one or more system libraries are usually linked in by default. Dynamic linking Modern operating system environments allow dynamic linking, or the postponing of the resolving of some undefined symbols until a program is run. That means that the executable still contains undefined symbols, plus a list of objects or libraries that will provide definitions for these. Loading the program will load these objects/libraries as well, and perform a final linking. Dynamic linking offers three advantages: Often-used libraries (for example the standard system libraries) need to be stored in only one location, not duplicated in every single binary. If a library is upgraded or replaced, all programs using it dynamically will immediately benefit from the corrections. Static builds would have to be re-linked first. The binary executable file size is smaller than its statically linked counterpart. Static building In a statically built program, no dynamic link
https://en.wikipedia.org/wiki/Algal%20mat	Algal mats are one of many types of microbial mat that forms on the surface of water or rocks. They are typically composed of blue-green cyanobacteria and sediments. Formation occurs when alternating layers of blue-green bacteria and sediments are deposited or grow in place, creating dark-laminated layers. Stromatolites are prime examples of algal mats. Algal mats played an important role in the Great Oxidation Event on Earth some 2.3 billion years ago. Algal mats can become a significant ecological problem, if the mats grow so expansive or thick as to disrupt the other underwater marine life by blocking the sunlight or producing toxic chemicals. Cyanobacteria forming algal mats Cyanobacteria found in sedimentary rocks indicate that bacterial life began on Earth during the Precambrian age. Fossilized cyanobacteria are commonly found in rocks that date back to Mesoproterozoic. Cyanobacteria are photoautotrophs in nature; they convert carbon dioxide and sunlight into food and energy via photosynthesis. Some species are also able to fix atmospheric nitrogen and convert it into the biologically-usable form of nitrate or nitrite. This gives them competitive advantage over other organisms that may be limited by the shortage of biologically available nitrogen. The cyanobacteria colonies contain two types of cells, the regular cells with chlorophyll carrying out the photosynthesis, and heterocysts which fix the nitrogen. These heterocysts have thick walls and lack chlorophyll, both of which limits their exposure to oxygen, the presence of which inhibits nitrogen fixation. For the same reason, fixation may also be limited to nighttime when the light-dependent reactions of photosynthesis are shut down, minimizing oxygen production. Stromatolites Stromatolites are alternating layers of cyanobacteria and sediments. The grain size of sediment portion of stromatolites is affected by the depositional environment. During the Proterozoic, stromatolites' compositions were dominated
https://en.wikipedia.org/wiki/Lanczos%20tensor	The Lanczos tensor or Lanczos potential is a rank 3 tensor in general relativity that generates the Weyl tensor. It was first introduced by Cornelius Lanczos in 1949. The theoretical importance of the Lanczos tensor is that it serves as the gauge field for the gravitational field in the same way that, by analogy, the electromagnetic four-potential generates the electromagnetic field. Definition The Lanczos tensor can be defined in a few different ways. The most common modern definition is through the Weyl–Lanczos equations, which demonstrate the generation of the Weyl tensor from the Lanczos tensor. These equations, presented below, were given by Takeno in 1964. The way that Lanczos introduced the tensor originally was as a Lagrange multiplier on constraint terms studied in the variational approach to general relativity. Under any definition, the Lanczos tensor H exhibits the following symmetries: The Lanczos tensor always exists in four dimensions but does not generalize to higher dimensions. This highlights the specialness of four dimensions. Note further that the full Riemann tensor cannot in general be derived from derivatives of the Lanczos potential alone. The Einstein field equations must provide the Ricci tensor to complete the components of the Ricci decomposition. The Curtright field has a gauge-transformation dynamics similar to that of Lanczos tensor. But Curtright field exists in arbitrary dimensions > 4D. Weyl–Lanczos equations The Weyl–Lanczos equations express the Weyl tensor entirely as derivatives of the Lanczos tensor: where is the Weyl tensor, the semicolon denotes the covariant derivative, and the subscripted parentheses indicate symmetrization. Although the above equations can be used to define the Lanczos tensor, they also show that it is not unique but rather has gauge freedom under an affine group. If is an arbitrary vector field, then the Weyl–Lanczos equations are invariant under the gauge transformation where the subsc
https://en.wikipedia.org/wiki/Rainbow%20table	A rainbow table is a precomputed table for caching the outputs of a cryptographic hash function, usually for cracking password hashes. Passwords are typically stored not in plain text form, but as hash values. If such a database of hashed passwords falls into the hands of an attacker, they can use a precomputed rainbow table to recover the plaintext passwords. A common defense against this attack is to compute the hashes using a key derivation function that adds a "salt" to each password before hashing it, with different passwords receiving different salts, which are stored in plain text along with the hash. Rainbow tables are a practical example of a space–time tradeoff: they use less computer processing time and more storage than a brute-force attack which calculates a hash on every attempt, but more processing time and less storage than a simple table that stores the hash of every possible password. Rainbow tables were invented by Philippe Oechslin as an application of an earlier, simpler algorithm by Martin Hellman. Background For user authentication, passwords are stored either as plaintext or hashes. Since passwords stored as plaintext are easily stolen if database access is compromised, databases typically store hashes instead. Thus, no one – including the authentication system – can learn a password merely by looking at the value stored in the database. When a user enters a password for authentication, a hash is computed for it and then compared to the stored hash for that user. Authentication fails if the two hashes do not match; moreover, authentication would equally fail if a hashed value were entered as a password, since the authentication system would hash it a second time. To learn a password from a hash is to find a string which, when input into the hash function, creates that same hash. This is the same as inverting the hash function. Though brute-force attacks (e.g. dictionary attacks) may be used to try to invert a hash function, they can bec
https://en.wikipedia.org/wiki/Strained%20silicon%20directly%20on%20insulator	Strained silicon directly on insulator (SSDOI) is a procedure developed by IBM which removes the silicon germanium layer in the strained silicon process leaving the strained silicon directly on the insulator. In contrast, strained silicon on SGOI provides a strained silicon layer on a relaxed silicon germanium layer on an insulator, as developed by MIT. References Semiconductor device fabrication
https://en.wikipedia.org/wiki/Virtual%20assistant%20%28occupation%29	A virtual assistant (typically abbreviated to VA, also called a virtual office assistant) is generally self-employed and provides professional administrative, technical, or creative (social) assistance to clients remotely from a home office. Because virtual assistants are independent contractors rather than employees, clients are not responsible for any employee-related taxes, insurance, or benefits, except in the context that those indirect expenses are included in the VA's fees. Clients also avoid the logistical problem of providing extra office space, equipment, or supplies. Clients pay for 100% productive work and can work with virtual assistants, individually, or in multi-VA firms to meet their exact needs. Virtual assistants usually work for other small businesses but can also support busy executives. It is estimated that there are as few as 5,000 to 10,000 or as many as 25,000 virtual assistants worldwide. The profession is growing in centralized economies with "fly-in fly-out" staffing practices. Pay and salary In terms of pay, according to Glassdoor, the annual salary for virtual assistants in the US is $35,922. However, worldwide, many virtual assistants work as freelancers on an hourly wage. One recent survey involving 400 virtual assistants on the popular freelancer site Upwork shows a huge discrepancy in hourly pay commanded by virtual assistants in different countries. Modes of communication Common modes of communication and data delivery include the internet, e-mail and phone-call conferences, online work spaces, and fax machine. Increasingly, virtual assistants are utilizing technology such as Skype and Zoom, Slack, as well as Google Voice. Professionals in this business work on a contractual basis, and a long-lasting cooperation is standard. Typically, administrative experience in an office is expected at such positions as executive assistant, office manager/supervisor, secretary, legal assistant, paralegal, legal secretary, real estate assistant,
https://en.wikipedia.org/wiki/Poincar%C3%A9%20recurrence%20theorem	In mathematics and physics, the Poincaré recurrence theorem states that certain dynamical systems will, after a sufficiently long but finite time, return to a state arbitrarily close to (for continuous state systems), or exactly the same as (for discrete state systems), their initial state. The Poincaré recurrence time is the length of time elapsed until the recurrence. This time may vary greatly depending on the exact initial state and required degree of closeness. The result applies to isolated mechanical systems subject to some constraints, e.g., all particles must be bound to a finite volume. The theorem is commonly discussed in the context of ergodic theory, dynamical systems and statistical mechanics. Systems to which the Poincaré recurrence theorem applies are called conservative systems. The theorem is named after Henri Poincaré, who discussed it in 1890 and proved by Constantin Carathéodory using measure theory in 1919. Precise formulation Any dynamical system defined by an ordinary differential equation determines a flow map f t mapping phase space on itself. The system is said to be volume-preserving if the volume of a set in phase space is invariant under the flow. For instance, all Hamiltonian systems are volume-preserving because of Liouville's theorem. The theorem is then: If a flow preserves volume and has only bounded orbits, then, for each open set, any orbit that intersects this open set intersects it infinitely often. Discussion of proof The proof, speaking qualitatively, hinges on two premises: A finite upper bound can be set on the total potentially accessible phase space volume. For a mechanical system, this bound can be provided by requiring that the system is contained in a bounded physical region of space (so that it cannot, for example, eject particles that never return) – combined with the conservation of energy, this locks the system into a finite region in phase space. The phase volume of a finite element under dynamics is conse
https://en.wikipedia.org/wiki/Voltage%20reference	A voltage reference is an electronic device that ideally produces a fixed (constant) voltage irrespective of the loading on the device, power supply variations, temperature changes, and the passage of time. Voltage references are used in power supplies, analog-to-digital converters, digital-to-analog converters, and other measurement and control systems. Voltage references vary widely in performance; a regulator for a computer power supply may only hold its value to within a few percent of the nominal value, whereas laboratory voltage standards have precisions and stability measured in parts per million. In metrology The earliest voltage references or standards were wet-chemical cells such as the Clark cell and Weston cell, which are still used in some laboratory and calibration applications. Laboratory-grade Zener diode secondary solid-state voltage standards used in metrology can be constructed with a drift of about 1 part per million per year. The value of the "conventional" volt is now maintained by superconductive integrated circuits using the Josephson Effect to get a voltage to an accuracy of 1 parts per billion or better, the Josephson voltage standard. The paper titled, "Possible new effects in superconductive tunnelling", was published by Brian David Josephson in 1962 and earned Josephson the Nobel Prize in Physics in 1973. Formerly, mercury batteries were much used as convenient voltage references especially in portable instruments such as photographic light meters; mercury batteries had a very stable discharge voltage over their useful life. Solid state devices Any semiconductor diode has an exponential voltage/current characteristic that gives an effective "knee" voltage sometimes used as a voltage reference. This voltage ranges from 0.3 V for germanium diodes up to about 3 volts for certain light emitting diodes. These devices have a strong temperature dependence, which may make them useful for temperature measurement or for compensating bias i
https://en.wikipedia.org/wiki/Immunopathology	Immunopathology is a branch of medicine that deals with immune responses associated with disease. It includes the study of the pathology of an organism, organ system, or disease with respect to the immune system, immunity, and immune responses. In biology, it refers to damage caused to an organism by its own immune response, as a result of an infection. It could be due to mismatch between pathogen and host species, and often occurs when an animal pathogen infects a human (e.g. avian flu leads to a cytokine storm which contributes to the increased mortality rate). Types of Immunity In all vertebrates, there are two different kinds of immunities: Innate and Adaptive immunity. Innate immunity is used to fight off non-changing antigens and is therefore considered nonspecific. It is usually a more immediate response than the adaptive immune system, usually responding within minutes to hours. It is composed of physical blockades such as the skin, but also contains nonspecific immune cells such as dendritic cells, macrophages, and basophils. The second form of immunity is Adaptive immunity. This form of immunity requires recognition of the foreign antigen before a response is produced. Once the antigen is recognized, a specific response is produced in order to destroy the specific antigen. Because of its tailored response characteristic, adaptive immunity is considered to be specific immunity. A key part of adaptive immunity that separates it from innate is the use of memory to combat the antigen in the future. When the antigen is originally introduced, the organism does not have any receptors for the antigen so it must generate them from the first time the antigen is present. The immune system then builds a memory of that antigen, which enables it to recognize the antigen quicker in the future and be able to combat it quicker and more efficiently. The more the system is exposed to the antigen, the quicker it will build up its responsiveness. Nested within Adaptive immu
https://en.wikipedia.org/wiki/Portable%20character%20set	Portable Character Set is a set of 103 characters which, according to the POSIX standard, must be present in any character set. Compared to ASCII, the Portable Character Set lacks some control characters, and does not prescribe any particular value encoding. The Portable Character Set is a superset of the Basic Execution Character Set as defined by ANSI C. Character Classes Characters grouped by their class. References Character sets POSIX
https://en.wikipedia.org/wiki/Email%20privacy	Email privacy is a broad topic dealing with issues of unauthorized access to, and inspection of, electronic mail, or unauthorized tracking when a user reads an email. This unauthorized access can happen while an email is in transit, as well as when it is stored on email servers or on a user's computer, or when the user reads the message. In countries with a constitutional guarantee of the secrecy of correspondence, whether email can be equated with letterstherefore having legal protection from all forms of eavesdroppingis disputed because of the very nature of email.</ref> In 2022 a lookback at an 1890 law review article about personal privacy (the "right to be left alone”) noted how "digital technology has been allowed to invade our lives" both by personal choice and behavior, and also by various forms of ongoing monitoring. An email has to go through potentially untrustworthy intermediate computers (email servers, ISPs) before reaching its destination, and there is no way to verify if it was accessed by an unauthorized entity. Through the process of information being sent from the user's computer to the email service provider, data acquisition is taking place, most of the time without the user knowing. There are certain data collection methods (routers) that are used for data privacy concerns, but there are others that can be harmful to the user. This is different from a letter sealed in an envelope, where, by close inspection of the envelope, it might be possible to determine if it had been previously opened. In that sense, an email is much like a postcard, the contents of which are visible to anyone who handles it. There are certain technological workarounds that make unauthorized access to email difficult, if not impossible. However, since email messages frequently cross national boundaries, and different countries have different rules and regulations governing who can access an email, email privacy is a complicated issue. Companies may have email policies
https://en.wikipedia.org/wiki/Comparison%20of%20accounting%20software	The following comparison of accounting software documents the various features and differences between different professional accounting software, personal and small enterprise software, medium-sized and large-sized enterprise software, and other accounting packages. The comparison only focus considering financial and external accounting functions. No comparison is made for internal/management accounting, cost accounting, budgeting, or integrated MAS accounting. Free and open source software Proprietary software Systems listed on a light purple background are no longer in active development. Further details See also List of personal finance software List of ERP software packages Point of sale Comparison of development estimation software List of project management software References Accounting software Lists of software Accounting Software
https://en.wikipedia.org/wiki/Data%20buffer	In computer science, a data buffer (or just buffer) is a region of a memory used to store data temporarily while it is being moved from one place to another. Typically, the data is stored in a buffer as it is retrieved from an input device (such as a microphone) or just before it is sent to an output device (such as speakers). However, a buffer may be used when data is moved between processes within a computer. That is comparable to buffers in telecommunication. Buffers can be implemented in a fixed memory location in hardware or by using a virtual data buffer in software that points at a location in the physical memory. In all cases, the data stored in a data buffer are stored on a physical storage medium. A majority of buffers are implemented in software, which typically use the faster RAM to store temporary data because of the much faster access time compared with hard disk drives. Buffers are typically used when there is a difference between the rate at which data is received and the rate at which it can be processed, or in the case that these rates are variable, for example in a printer spooler or in online video streaming. In the distributed computing environment, data buffer is often implemented in the form of burst buffer, which provides distributed buffering service. A buffer often adjusts timing by implementing a queue (or FIFO) algorithm in memory, simultaneously writing data into the queue at one rate and reading it at another rate. Applications Buffers are often used in conjunction with I/O to hardware, such as disk drives, sending or receiving data to or from a network, or playing sound on a speaker. A line to a rollercoaster in an amusement park shares many similarities. People who ride the coaster come in at an unknown and often variable pace, but the roller coaster will be able to load people in bursts (as a coaster arrives and is loaded). The queue area acts as a buffer—a temporary space where those wishing to ride wait until the ride is availab
https://en.wikipedia.org/wiki/Adelphogamy	Adelphogamy is a form of sexual partnership between sibling eukaryotes, especially in some species of fungi, flowering plants or ants, or in humans. In flowering plants, adelphogamy refers to sibling pollination: pollen and stigma belong to two individuals which derives from same mother plant. In sociology, the term adelphogamy or adelphic polyandry may also refer to fraternal polyandry, or to an incestuous relationship between a brother and sister. See also Incest between twins List of coupled siblings References External links Reproduction Incest
https://en.wikipedia.org/wiki/Embedded%20C%2B%2B	Embedded C++ (EC++) is a dialect of the C++ programming language for embedded systems. It was defined by an industry group led by major Japanese central processing unit (CPU) manufacturers, including NEC, Hitachi, Fujitsu, and Toshiba, to address the shortcomings of C++ for embedded applications. The goal of the effort is to preserve the most useful object-oriented features of the C++ language yet minimize code size while maximizing execution efficiency and making compiler construction simpler. The official website states the goal as "to provide embedded systems programmers with a subset of C++ that is easy for the average C programmer to understand and use". Differences from C++ Embedded C++ excludes some features of C++. Some compilers, such as those from Green Hills and IAR Systems, allow certain features of ISO/ANSI C++ to be enabled in Embedded C++. IAR Systems calls this "Extended Embedded C++". Compilation An EC++ program can be compiled with any C++ compiler. But, a compiler specific to EC++ may have an easier time doing optimization. Compilers specific to EC++ are provided by companies such as: IAR Systems Freescale Semiconductor, (spin-off from Motorola in 2004 who had acquired Metrowerks in 1999) Tasking Software, part of Altium Limited Green Hills Software Criticism The language has had a poor reception with many expert C++ programmers. In particular, Bjarne Stroustrup says, "To the best of my knowledge EC++ is dead (2004), and if it isn't it ought to be." In fact, the official English EC++ website has not been updated since 2002. Nevertheless, a restricted subset of C++ (based on Embedded C++) has been adopted by Apple Inc. as the exclusive programming language to create all I/O Kit device drivers for Apple's macOS, iPadOS and iOS operating systems of the popular Macintosh, iPhone, and iPad products. Apple engineers felt the exceptions, multiple inheritance, templates, and runtime type information features of standard C++ were either insuffici
https://en.wikipedia.org/wiki/Dynamic%20imaging	Dynamic imaging is the amalgamation of digital imaging, image editing, and workflow automation. It is used to automate the creation of images by zooming, panning, colorize and performing other image processing and color management operations on a copy of a digital master. Categories Dynamic imaging technology falls into three categories: Script dynamic imaging: A shell script is used to automate repeated tasks in programs. Batch dynamic imaging (IIP based imaging server): An engine is used in batch processing of images. Real-time dynamic imaging: An imaging server allows realtime rendering of images, text, logos and colorization based on internal and external data sources. Device transcoding delivers real-time dynamic imaging features to any device or display without the need of predefined templates. Device transcoded imaging can be used for mobile devices or as an engine behind RFID to create visual messages/offers in narrowcasting/1to1 environments without the need of heavy (flash) clients. References Image processing Graphics software
https://en.wikipedia.org/wiki/Kaczmarz%20method	The Kaczmarz method or Kaczmarz's algorithm is an iterative algorithm for solving linear equation systems . It was first discovered by the Polish mathematician Stefan Kaczmarz, and was rediscovered in the field of image reconstruction from projections by Richard Gordon, Robert Bender, and Gabor Herman in 1970, where it is called the Algebraic Reconstruction Technique (ART). ART includes the positivity constraint, making it nonlinear. The Kaczmarz method is applicable to any linear system of equations, but its computational advantage relative to other methods depends on the system being sparse. It has been demonstrated to be superior, in some biomedical imaging applications, to other methods such as the filtered backprojection method. It has many applications ranging from computed tomography (CT) to signal processing. It can be obtained also by applying to the hyperplanes, described by the linear system, the method of successive projections onto convex sets (POCS). Algorithm 1: Kaczmarz algorithm Let be a system of linear equations, let be the number of rows of A, be the th row of complex-valued matrix , and let be arbitrary complex-valued initial approximation to the solution of . For compute: where and denotes complex conjugation of . If the system is consistent, converges to the minimum-norm solution, provided that the iterations start with the zero vector. A more general algorithm can be defined using a relaxation parameter There are versions of the method that converge to a regularized weighted least squares solution when applied to a system of inconsistent equations and, at least as far as initial behavior is concerned, at a lesser cost than other iterative methods, such as the conjugate gradient method. Algorithm 2: Randomized Kaczmarz algorithm In 2009, a randomized version of the Kaczmarz method for overdetermined linear systems was introduced by Thomas Strohmer and Roman Vershynin in which the i-th equation is selected randomly with prob
https://en.wikipedia.org/wiki/North%20%26%20South%20%28video%20game%29	North & South is a strategy action game released in 1989 for the Amiga, and Atari ST and ported to the Nintendo Entertainment System, Amstrad CPC, MSX, MS-DOS, Commodore 64 and ZX Spectrum. It was developed and published by Infogrames. North & South is an offshoot of the Belgian comic series Les Tuniques Bleues (by Raoul Cauvin and Louis Salverius/Willy Lambillotte, from Dupuis) which is based on the American Civil War. The player basically acts out the Civil War, choosing to play as either the North or the South. The player may choose to start the game year from 1861 (the year the Civil War erupted) to 1864. Each year has a different array of armies and states that each side starts with. North & South contains humorous elements, such as parodies of national anthems, which are accessible when the player selects one of the different languages supported by the game: (English, French, Spanish, German or Italian). Gameplay Taking a simplified board interface, the game features a strategic map of the United States separated into states and territories, where army units are moved around. In each state which has a railway station, there is a fort, the capture of which leads to the player overtaking the whole state. Otherwise, capturing a state involves simple movement, unless there is an enemy army present on the state's title. Armies can be reinforced in two ways. By turning on an option at the main menu the player controlling the state of North Carolina will get periodic reinforcements by ship. Also, railways generate money which in turn generates soldiers. Moving their army units, the player may expand westwards into unoccupied territory. If two antagonistic armies clash, it will result in a battle. Normally, battle is resolved in a real time action element. However, there is an option on the main menu where the player can turn off in-game missions and battles so that game-play is as in a board game. Whenever opposing armies meet in board-game mode, the results
https://en.wikipedia.org/wiki/DesktopBSD	DesktopBSD is a Unix-derived, desktop-oriented operating system based on FreeBSD. Its goal was to combine the stability of FreeBSD with the ease-of-use of K Desktop Environment 3, which is the default graphical user interface. History and development DesktopBSD is essentially a customized installation of FreeBSD and is not a fork of it. DesktopBSD was always based on FreeBSD's latest stable branch but incorporated certain customized, pre-installed software such as KDE and DesktopBSD utilities and configuration files. A common misconception about DesktopBSD was that it was intended as a rival to TrueOS as a BSD-based desktop distribution, since they were similar in structure and goals. However, DesktopBSD was started approximately one year before the PC-BSD project, despite the fact that the first PC-BSD release came out before DesktopBSD's. Neither project intended to rival the other and they were completely independent with distinctive features and intended outcomes: for example, DesktopBSD uses ports and packages for additional software installation, whereas PC-BSD introduced PBIs. The final release was 1.7 which was made available on 7 September 2009. The release announcement stated "This is the last and final release of the DesktopBSD project" because the lead developer could no longer contribute the time required to maintain it. In May 2010 DesktopBSD was restarted under new leadership though development and announcements stopped soon afterwards. On 10 March 2013, a forum post appeared announcing that the project was "in the process of being revived." The roadmap for DesktopBSD 2.0 was announced in September 2015 on the DesktopBSD site, along with posted screenshots of a GNOME3-based desktop. Graphical features Installer allowing to partition disks and create users Tool for managing, installing and updating software using FreeBSD ports system Management of network interfaces and mounting/unmounting drives 1.7 release The 1.7 release includes FreeBS
https://en.wikipedia.org/wiki/Hydrolyzed%20vegetable%20protein	Hydrolyzed vegetable protein (HVP) products are foodstuffs obtained by protein hydrolysis and are used as ingredients to create a bouillon (broth) taste without the vegetables, bones, simmering, or other standard elements of creating bouillon from scratch. Regarding the production process, a distinction can be made between acid-hydrolyzed vegetable protein (aHVP), enzymatically produced HVP, and other seasonings, e.g., fermented soy sauce. Hydrolyzed vegetable protein products are particularly used to round off the taste of soups, sauces, meat products, snacks, and other dishes, as well as for the production of ready-to-cook soups and bouillons. History Food technologists have long known that protein hydrolysis produces a meat bouillon-like odor and taste. In 1831, Berzelius obtained products having a meat bouillon taste when hydrolysing proteins with hydrochloric acid. Julius Maggi produced acid-catalyzed hydrolyzed vegetable protein industrially for the first time in 1886. In 1906, Fischer found that amino acids contributed to the specific taste. In 1954, D. Phillips found that the bouillon odor required the presence of proteins containing threonine. Another important substance giving a characteristic taste is glutamic acid. Manufacture Almost all products rich in protein are suitable for the production of HVP. Today, it is made mainly from protein resources of vegetable origin, such as defatted oil seeds (soybean meal, grapeseed meal) and protein from maize (Corn gluten meal), wheat (gluten), pea, and rice. The process and the feedstock determines the organoleptic properties of the end product. Proteins consist of chains of amino acids joined through amide bonds. When subjected to hydrolysis (hydrolyzed), the protein is broken down into its component amino acids. In aHVP, hydrochloric acid is used for hydrolysis. The remaining acid is then neutralized by mixing with an alkali such as sodium hydroxide, which leaves behind table salt, which comprises up to 20%
https://en.wikipedia.org/wiki/Sagittal%20plane	The sagittal plane (; also known as the longitudinal plane) is an anatomical plane that divides the body into right and left sections. It is perpendicular to the transverse and coronal planes. The plane may be in the center of the body and divide it into two equal parts (mid-sagittal), or away from the midline and divide it into unequal parts (para-sagittal). The term sagittal was coined by Gerard of Cremona. Variations in terminology Examples of sagittal planes include: The terms median plane or mid-sagittal plane are sometimes used to describe the sagittal plane running through the midline. This plane cuts the body into halves (assuming bilateral symmetry), passing through midline structures such as the navel and spine. It is one of the planes which, combined with the Umbilical plane, defines the four quadrants of the human abdomen. The term parasagittal is used to describe any plane parallel or adjacent to a given sagittal plane. Specific named parasagittal planes include: The midclavicular line crosses through the clavicle. Lateral sternal and parasternal planes. The term sagittal is derived from the Latin word sagitta, meaning "arrow". An image of an arrow piercing a body and passing from front (anterior) to back (posterior) on a parabolic trajectory would be one way to demonstrate the derivation of the term. Another explanation would be the notching of the sagittal suture posteriorly by the lambdoidal suture —similar to feathers on an arrow. Sagittal axis or anterior-posterior axis is the axis perpendicular to the coronal plane, i.e., the one formed by the intersection of the sagittal and the transversal planes Coronal axis, medial-lateral axis, or frontal axis is the axis perpendicular to the sagittal plane, i.e., the one formed by the intersection of the coronal and the transversal planes. Extension and flexion are the movements of limbs within the sagittal plane. Abduction and adduction'' are terms for movements of limbs within the coronal plane.
https://en.wikipedia.org/wiki/Calcium%20caseinate	Calcium caseinate is one of several milk proteins derived from casein in skim and 1% milk. Calcium caseinate has a papery, sweet and overall bland flavor, and is primarily used in meal preparation and fat breakdown. Caseinates are produced by adding an alkali to another derivative of casein, acid casein. The type of caseinate is determined by the cation added alongside the acid casein. Other cations used to form caseinates besides calcium include ammonium, potassium, and sodium. Calcium caseinate contains about 17% glutamic acid. This provides many health benefits such as treating low blood sugar, improving memory and focus, boosting the immune system and treating intellectual disorders. Calcium caseinate is also soluble and does not clot in the stomach. Calcium caseinate is mostly composed of 3.5% moisture, 1.0% fat, 90.9% protein, 0.1% lactose, 4.5% ash, although this may vary slightly by manufacturer. Calcium caseinate is semi-soluble in water, contrary to acid casein and rennet casein which are not soluble in water. Sodium caseinate is more water soluble than calcium caseinate, due to its polarity. Physical properties Caseins are found in milk which is held together by colloidal calcium phosphate. Calcium caseinate is generally stable at a pH above 5.7, and appears as a milky liquid. This is unlike ammonium, potassium, and sodium caseinates, which are practically clear. At a neutral or acidic pH, casein is relatively insoluble in water, and is easily separated from other milk proteins, sugars, and minerals. Casein can be resuspended by alternating the pH levels with NaOH or , resulting in aqueous solutions of sodium caseinate or calcium caseinate. Most caseinates are capable of withstanding temperatures of up to 140°C (284°F), however calcium caseinate is influenced by heat with temperatures as low as 50°C (122°F). Calcium is a divalent cation, allowing it to form bonds with several caseinate anions. The binding of a calcium ion is able to reduce the elect
https://en.wikipedia.org/wiki/Inter-Language%20Unification	Inter-Language Unification or ILU is a method for computer systems to exchange data, bridging differences in the way systems represent the various kinds of data. Even if two systems run on the same computer, or on identical computer hardware, many differences arise from the use of different computer languages to build the systems. The object interfaces provided by ILU hide implementation distinctions between different languages, between different address spaces, and between operating system types. ILU can be used to build multi-lingual object-oriented libraries ("class libraries") with well-specified language-independent interfaces. It can also be used to implement distributed systems. It can also be used to define and document interfaces between the modules of non-distributed programs. ILU interfaces can be specified in either the Object Management Group's CORBA Interface Definition Language (OMG IDL), or ILU's Interface Specification Language (ISL). History ILU was developed as an Open Source project at the Xerox Palo Alto Research Center (Xerox PARC) from 1991 until 2000. The last release was 2.0beta1. From 1997 to 2000, ILU was used as the foundation for experimental work on a "next generation" HTTP protocol by the World Wide Web Consortium's HTTP-NG activity. As a result of this work, a particularly efficient experimental RPC protocol called "w3ng" was developed, along with a way of efficiently multiplexing a single TCP connection into multiple channels in both directions, called "w3mux". The results of the HTTP-NG experiment were presented at the 2000 World Wide Web Conference. Features The last release supported the programming languages C++ (Corba2 mapping), ANSI C, Python, Java, and Common Lisp. Contributed support was also available for Modula-3, Guile Scheme, and Perl 5. ILU has been installed on most flavors of UNIX (SunOS, Solaris, HP-UX, AIX, OSF, IRIX, FreeBSD, Linux, LynxOS, SCO Unix, etc.) and MS-Windows (3.1, 95, NT). It supported both th
https://en.wikipedia.org/wiki/Commemorative%20plaque	A commemorative plaque, or simply plaque, or in other places referred to as a historical marker, historic marker, or historic plaque, is a plate of metal, ceramic, stone, wood, or other material, typically attached to a wall, stone, or other vertical surface, and bearing text or an image in relief, or both, to commemorate one or more persons, an event, a former use of the place, or some other thing. Many modern plaques and markers are used to associate the location where the plaque or marker is installed with the person, event, or item commemorated as a place worthy of visit. A monumental plaque or tablet commemorating a deceased person or persons, can be a simple form of church monument. Most modern plaques affixed in this way are commemorative of something, but this is not always the case, and there are purely religious plaques, or those signifying ownership or affiliation of some sort. A plaquette is a small plaque, but in English, unlike many European languages, the term is not typically used for outdoor plaques fixed to walls. Historical Benin Kingdom The Benin Empire, which flourished in present-day Nigeria between the thirteenth and nineteenth centuries, had an exceedingly rich sculptural tradition. One of the kingdom's chief sites of cultural production was the elaborate ceremonial court of the Oba (divine king) at the palace in Benin. Among the wide range of artistic forms produced at the court were rectangular brass or bronze plaques. At least a portion of these plaques, which were mainly created from the thirteenth through sixteenth centuries, commemorate significant persons and events associated with the Oba's court, including important battles during Benin's sixteenth century expansionary period. Medieval Europe Brass or bronze memorial plaques were produced throughout medieval Europe from at least the early thirteenth through the sixteenth centuries as a form of sepulchral memorial generally inset into the walls of churches or surfaces of tombs
https://en.wikipedia.org/wiki/HoneyMonkey	HoneyMonkey, short for Strider HoneyMonkey Exploit Detection System, is a Microsoft Research honeypot. The implementation uses a network of computers to crawl the World Wide Web searching for websites that use browser exploits to install malware on the HoneyMonkey computer. A snapshot of the memory, executables and registry of the honeypot computer is recorded before crawling a site. After visiting the site, the state of memory, executables, and registry is recorded and compared to the previous snapshot. The changes are analyzed to determine if the visited site installed any malware onto the client honeypot computer. HoneyMonkey is based on the honeypot concept, with the difference that it actively seeks websites that try to exploit it. The term was coined by Microsoft Research in 2005. With honeymonkeys it is possible to find open security holes that are not yet publicly known but are being exploited by attackers. Technology A single HoneyMonkey is an automated program that tries to mimic the action of a user surfing the net. A series of HoneyMonkeys are run on virtual machines running Windows XP, at various levels of patching — some are fully patched, some fully vulnerable, and others in between these two extremes. The HoneyMonkey program records every read or write of the file system and registry, thus keeping a log of what data was collected by the web-site and what software was installed by it. Once the program leaves a site, this log is analyzed to determine if any malware has been loaded. In such cases, the log of actions is sent for further manual analysis to an external controller program, which logs the exploit data and restarts the virtual machine to allow it to crawl other sites starting in a known uninfected state. Initiating crawling Out of the 10 billion plus web pages, there are many legitimate sites that do not use exploit browser vulnerabilities, and to start crawling from most of these sites would be a waste of resources. An initial list was th
https://en.wikipedia.org/wiki/Isolated%20system	In physical science, an isolated system is either of the following: a physical system so far removed from other systems that it does not interact with them. a thermodynamic system enclosed by rigid immovable walls through which neither mass nor energy can pass. Though subject internally to its own gravity, an isolated system is usually taken to be outside the reach of external gravitational and other long-range forces. This can be contrasted with what (in the more common terminology used in thermodynamics) is called a closed system, being enclosed by selective walls through which energy can pass as heat or work, but not matter; and with an open system, which both matter and energy can enter or exit, though it may have variously impermeable walls in parts of its boundaries. An isolated system obeys the conservation law that its total energy–mass stays constant. Most often, in thermodynamics, mass and energy are treated as separately conserved. Because of the requirement of enclosure, and the near ubiquity of gravity, strictly and ideally isolated systems do not actually occur in experiments or in nature. Though very useful, they are strictly hypothetical. Classical thermodynamics is usually presented as postulating the existence of isolated systems. It is also usually presented as the fruit of experience. Obviously, no experience has been reported of an ideally isolated system. It is, however, the fruit of experience that some physical systems, including isolated ones, do seem to reach their own states of internal thermodynamic equilibrium. Classical thermodynamics postulates the existence of systems in their own states of internal thermodynamic equilibrium. This postulate is a very useful idealization. In the attempt to explain the idea of a gradual approach to thermodynamic equilibrium after a thermodynamic operation, with entropy increasing according to the second law of thermodynamics, Boltzmann’s H-theorem used equations, which assumed a system (for exa
https://en.wikipedia.org/wiki/Heart%20symbol	The heart symbol is an ideograph used to express the idea of the "heart" in its metaphorical or symbolic sense. Represented by an anatomically inaccurate shape, the heart symbol is often used to represent the center of emotion, including affection and love, especially romantic love. It is sometimes accompanied or superseded by the "wounded heart" symbol, depicted as a heart symbol pierced with an arrow or as a heart symbol "broken" into two or more pieces, indicating lovesickness. History Similar shapes from antiquity Peepal leaves were used in artistic depictions of the Indus Valley civilisation: a heart-shaped pendant originating from there has been discovered and is now exhibited in the National Museum of India. In the 5th–6th century BC, the heart shape was used to represent the heart-shaped fruit of the plant silphium, a plant possibly used as a contraceptive and an aphrodisiac. Silver coins from Cyrene of the 5th–6th century BC bear a similar design, sometimes accompanied by a silphium plant and is understood to represent its seed or fruit. Since ancient times in Japan, the heart symbol has been called Inome (猪目), meaning the eye of a wild boar, and it has the meaning of warding off evil spirits. The decorations are used to decorate Shinto shrines, Buddhist temples, castles, and weapons. The oldest examples of this pattern are seen in some of the Japanese original tsuba (sword guard) of the style called toran gata tsuba (lit., inverted egg shaped tsuba) that were attached to swords from the sixth to seventh centuries, and part of the tsuba was hollowed out in the shape of a heart symbol. Earliest use The combination of the heart shape and its use within the heart metaphor was developed in the end of the Middle Ages, although the shape has been used in many ancient epigraphy monuments and texts. With possible early examples or direct predecessors in the 13th to 14th century, the familiar symbol of the heart representing love developed in the 15th century,
https://en.wikipedia.org/wiki/Monopole%20%28mathematics%29	In mathematics, a monopole is a connection over a principal bundle G with a section of the associated adjoint bundle. Physical interpretation Physically, the section can be interpreted as a Higgs field, where the connection and Higgs field should satisfy the Bogomolny equations and be of finite action. See also Nahm equations Instanton Magnetic monopole Yang–Mills theory References Differential geometry Mathematical physics
https://en.wikipedia.org/wiki/Differential%20graded%20algebra	In mathematics, in particular in homological algebra, a differential graded algebra is a graded associative algebra with an added chain complex structure that respects the algebra structure. Definition A differential graded algebra (or DG-algebra for short) A is a graded algebra equipped with a map which has either degree 1 (cochain complex convention) or degree −1 (chain complex convention) that satisfies two conditions: A more succinct way to state the same definition is to say that a DG-algebra is a monoid object in the monoidal category of chain complexes. A DG morphism between DG-algebras is a graded algebra homomorphism which respects the differential d. A differential graded augmented algebra (also called a DGA-algebra, an augmented DG-algebra or simply a DGA) is a DG-algebra equipped with a DG morphism to the ground ring (the terminology is due to Henri Cartan). Warning: some sources use the term DGA for a DG-algebra. Examples of DG-algebras Tensor algebra The tensor algebra is a DG-algebra with differential similar to that of the Koszul complex. For a vector space over a field there is a graded vector space defined as where . If is a basis for there is a differential on the tensor algebra defined component-wise sending basis elements to In particular we have and so Koszul complex One of the foundational examples of a differential graded algebra, widely used in commutative algebra and algebraic geometry, is the Koszul complex. This is because of its wide array of applications, including constructing flat resolutions of complete intersections, and from a derived perspective, they give the derived algebra representing a derived critical locus. De-Rham algebra Differential forms on a manifold, together with the exterior derivation and the exterior product form a DG-algebra. These have wide applications, including in derived deformation theory. See also de Rham cohomology. Singular cohomology The singular cohomology of a topological s
https://en.wikipedia.org/wiki/Point%20of%20interface	In telecommunications a point of interface (POI) is used to show the physical interface between two different carriers, such as a local exchange carrier (LEC) and a wireless carrier, or an LEC and an IntereXchange Carrier (IXC). This demarcation point often defines responsibility as well as serving as a point for testing. In many cases, a POI exists as a point of demarcation ("DEMARC") within an LEC building, and is established under "co-location" agreements. A long distance, wireless, or competitive local carrier "rents" space at the local telephone (usually tandem switch) location. This space is physically a "cage" in which a device for interconnecting telecom services is installed. This device was originally a wire frame with one side being accessed by the LEC, and the other side accessed by the other carrier. In recent years, "electronic frames" such as digital cross connect systems have been used as POI devices. Local exchange services are ordered from the local telephone carrier who delivers the service to their side of the POI. The other carrier then arranges to its own facilities (fiber, or other type of transport) into the POI and transports the service to its own network facilities. See also Federal Standard 1037C Local loop References
https://en.wikipedia.org/wiki/Sound%20recording%20and%20reproduction	Sound recording and reproduction is the electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording technology are analog recording and digital recording. Acoustic analog recording is achieved by a microphone diaphragm that senses changes in atmospheric pressure caused by acoustic sound waves and records them as a mechanical representation of the sound waves on a medium such as a phonograph record (in which a stylus cuts grooves on a record). In magnetic tape recording, the sound waves vibrate the microphone diaphragm and are converted into a varying electric current, which is then converted to a varying magnetic field by an electromagnet, which makes a representation of the sound as magnetized areas on a plastic tape with a magnetic coating on it. Analog sound reproduction is the reverse process, with a larger loudspeaker diaphragm causing changes to atmospheric pressure to form acoustic sound waves. Digital recording and reproduction converts the analog sound signal picked up by the microphone to a digital form by the process of sampling. This lets the audio data be stored and transmitted by a wider variety of media. Digital recording stores audio as a series of binary numbers (zeros and ones) representing samples of the amplitude of the audio signal at equal time intervals, at a sample rate high enough to convey all sounds capable of being heard. A digital audio signal must be reconverted to analog form during playback before it is amplified and connected to a loudspeaker to produce sound. Early history Long before sound was first recorded, music was recorded—first by written music notation, then also by mechanical devices (e.g., wind-up music boxes, in which a mechanism turns a spindle, which plucks metal tines, thus reproducing a melody). Automatic music reproduction traces back as far as the 9th century, when the Banū
https://en.wikipedia.org/wiki/RSA%20Secret-Key%20Challenge	The RSA Secret-Key Challenge was a series of cryptographic contests organised by RSA Laboratories with the intent of helping to demonstrate the relative security of different encryption algorithms. The challenge ran from 28 January 1997 until May 2007. Contest details For each contest, RSA had posted on its website a block of ciphertext and the random initialization vector used for encryption. To win, a contestant would have had to break the code by finding the original plaintext and the cryptographic key that will generate the posted ciphertext from the plaintext. The challenge consisted of one DES contest and twelve contests based around the block cipher RC5. Each of the RC5 contests is named after the variant of the RC5 cipher used. The name RC5-w/r/b indicates that the cipher used w-bit words, r rounds, and a key made up of b bytes. The contests are often referred to by the names of the corresponding distributed.net projects, for example RC5-32/12/9 is often known as RC5-72 due to the 72-bit key size. The first contest was DES Challenge III (and was also part of the DES Challenges) and was completed in 22 hours 15 minutes by distributed.net and the EFF's Deep Crack machine. In May 2007 RSA Laboratories announced the termination of the challenge, stating that they would not disclose the solutions to the remaining contents, and nor would they confirm or reward prize money for future solutions. On 8 September 2008 distributed.net announced that they would fund a prize of $4000 for the RC5-32/12/9 contest. Distributed.net The contests are associated with the distributed.net group, which had actively participated in the challenge by making use of distributed computing to perform a brute force attack. RC5-32/12/7 was completed on 19 October 1997, with distributed.net finding the winning key in 250 days and winning the US$10,000 prize. The recovered plaintext was: The unknown message is: It's time to move to a longer key length. RC5-32/12/8 also carried a US$
https://en.wikipedia.org/wiki/Self-documenting%20code	In computer programming, self-documenting (or self-describing) source code and user interfaces follow naming conventions and structured programming conventions that enable use of the system without prior specific knowledge. In web development, self-documenting refers to a website that exposes the entire process of its creation through public documentation, and whose public documentation is part of the development process. Objectives Commonly stated objectives for self-documenting systems include: Make source code easier to read and understand Minimize the effort required to maintain or extend legacy systems Reduce the need for users and developers of a system to consult secondary documentation sources such as code comments or software manuals Facilitate automation through self-contained knowledge representation Conventions Self-documenting code is ostensibly written using human-readable names, typically consisting of a phrase in a human language which reflects the symbol's meaning, such as article.numberOfWords or TryOpen. The code must also have a clear and clean structure so that a human reader can easily understand the algorithm used. Practical considerations There are certain practical considerations that influence whether and how well the objectives for a self-documenting system can be realized. uniformity of naming conventions consistency scope of the application and system requirements Examples Below is a very simple example of self-documenting code, using naming conventions in place of explicit comments to make the logic of the code more obvious to human readers. size_t count_alphabetic_chars(const char text) { if (text == NULL) return 0; size_t count = 0; while (text != '\0') { if (is_alphabetic(*text)) count++; text++; } return count; } Criticism Jef Raskin criticized the belief in "self-documenting" code by saying that code cannot explain the rationale behind why the program
https://en.wikipedia.org/wiki/All-or-nothing%20transform	In cryptography, an all-or-nothing transform (AONT), also known as an all-or-nothing protocol, is an encryption mode which allows the data to be understood only if all of it is known. AONTs are not encryption, but frequently make use of symmetric ciphers and may be applied before encryption. In exact terms, "an AONT is an unkeyed, invertible, randomized transformation, with the property that it is hard to invert unless all of the output is known." Algorithms The original AONT, the package transform, was described by Ronald L. Rivest in his 1997 paper "All-Or-Nothing Encryption and The Package Transform". The transform that Rivest proposed involved preprocessing the plaintext by XORing each plaintext block with that block's index encrypted by a randomly chosen key, then appending one extra block computed by XORing that random key and the hashes of all the preprocessed blocks. The result of this preprocessing is called the pseudomessage, and it serves as the input to the encryption algorithm. Undoing the package transform requires hashing every block of the pseudomessage except the last, XORing all the hashes with the last block to recover the random key, and then using the random key to convert each preprocessed block back into its original plaintext block. In this way, it's impossible to recover the original plaintext without first having access to every single block of the pseudomessage. Although Rivest's paper only gave a detailed description of the package transform as it applies to CBC mode, it can be implemented using a cipher in any mode. Therefore, there are multiple variants: the package ECB transform, package CBC transform, etc. In 1999 Victor Boyko proposed another AONT, provably secure under the random oracle model. Apparently at about the same time, D. R. Stinson proposed a different implementation of AONT, without any cryptographic assumptions. This implementation is a linear transform, perhaps highlighting some security weakness of the original de
https://en.wikipedia.org/wiki/Salesforce	Salesforce, Inc. is an American cloud-based software company headquartered in San Francisco, California. It provides customer relationship management (CRM) software and applications focused on sales, customer service, marketing automation, e-commerce, analytics, and application development. Founded by former Oracle executive Marc Benioff in February 1999, Salesforce grew quickly, making its IPO in 2004. As of September 2022, Salesforce is the 61st largest company in the world by market cap with a value of nearly US$153 billion. Salesforce's rapid growth made it the first cloud computing company to reach US$1billion in annual revenue, which it achieved in fiscal year 2009. It became the world's largest enterprise software firm in 2022. Salesforce ranked 136th on the most recent edition of the Fortune 500, making US$26.5billion in 2022. Since 2020, Salesforce has also been a component of the Dow Jones Industrial Average. History Salesforce was founded in 1999 by former Oracle executive Marc Benioff, together with Parker Harris, Dave Moellenhoff, and Frank Dominguez as a software as a service (SaaS) company. Two of Salesforce's earliest investors were Larry Ellison, the co-founder and first CEO of Oracle, and Halsey Minor, the founder of CNET. Salesforce was severely affected by the dot-com bubble bursting at the beginning of the new millennium, with the company laying off 20% of its workforce. Despite its losses, Salesforce continued strong during the early 2000s. Salesforce also gained notability during this period for its "the end of software" tagline and marketing campaign, in which it also hired actors to hold up signs with its slogan outside a Siebel Systems conference. Salesforce's revenue continued to increase from 2000 to 2003, with 2003's revenue skyrocketing from $5.4 million in the fiscal year 2001 to over $100 million by December 2003. Also in 2003, Salesforce held its first annual Dreamforce conference in San Francisco. In June 2004, the company had
https://en.wikipedia.org/wiki/Mobile%20malware	Mobile malware is malicious software that targets mobile phones or wireless-enabled Personal digital assistants (PDA), by causing the collapse of the system and loss or leakage of confidential information. As wireless phones and PDA networks have become more and more common and have grown in complexity, it has become increasingly difficult to ensure their safety and security against electronic attacks in the form of viruses or other malware. History The first known virus that affected mobiles, "Timofonica", originated in Spain and was identified by antivirus labs in Russia and Finland in June 2000. "Timofonica" sent SMS messages to GSM-capable mobile phones that read (in Spanish) "Information for you: Telefónica is fooling you." These messages were sent through the Internet SMS gateway of the MoviStar mobile operator. "Timofonica" ran on PCs and did not run on mobile devices so was not a true mobile malware In June 2004, it was discovered that a company called Ojam had engineered an anti-piracy Trojan hack in older versions of its mobile phone game, Mosquito. This sent SMS texts to the company without the user's knowledge. In July 2004, computer hobbyists released a proof-of-concept virus Cabir, that infects mobile phones running the Symbian operating system, spreading via Bluetooth wireless. This was the first true mobile malware In March 2005, it was reported that a computer worm called Commwarrior-A had been infecting Symbian series 60 mobile phones. This specific worm replicated itself through the phone's Multimedia Messaging Service (MMS), sending copies to contacts listed in the phone user's address book. In August 2010, Kaspersky Lab reported the trojan Trojan-SMS.AndroidOS.FakePlayer.a. This was the first SMS malware that affected Google's Android operating system, and which sent SMS messages to premium rate numbers without the owner's knowledge, accumulating huge bills. Currently, various antivirus software companies offer mobile antivirus software pr
https://en.wikipedia.org/wiki/Auto-defrost	Auto-defrost, automatic defrost or self-defrosting is a technique which regularly defrosts the evaporator in a refrigerator or freezer. Appliances using this technique are often called frost free, frostless, or no-frost. Mechanism The defrost mechanism in a refrigerator heats the cooling element (evaporator coil) for a short period of time and melts the frost that has formed on it. The resulting water drains through a duct at the back of the unit. Defrosting is controlled by an electric or electronic timer. For every 6, 8, 10, 12 or 24 hours of compressor operation, it turns on a defrost heater for 15 minutes to half an hour. The defrost heater, having a typical power rating of 350W to 600W, is often mounted just below the evaporator in top and bottom-freezer models. It can also be located below and in the middle of the evaporator in side-by-side models. It may be protected from short circuits by means of fusible links. In older refrigerators, the timer runs continuously. In newer designs, the timer only runs while the compressor runs, so the longer the refrigerator door is closed, the less time the heater will run for and the more energy is saved. A defrost thermostat opens the heater circuit when the evaporator temperature rises above a preset temperature, 40°F (5°C) or more, thereby preventing excessive heating of the freezer compartment. The defrost timer is such that either the compressor or the defrost heater is on, but not both at the same time. Inside the freezer, air is circulated by means of one or more fans. In a typical design cold air from the freezer compartment is ducted to the fresh food compartment and circulated back into the freezer compartment. Air circulation helps sublimate any ice or frost that may form on frozen items in the freezer compartment. While defrosting, this fan is stopped to prevent heated-up air from reaching the food compartment. Instead of the traditional cooling elements being embedded in the freezer liner, auto-defr
https://en.wikipedia.org/wiki/Ice%20pack	An ice pack or gel pack is a portable bag filled with water, refrigerant gel, or liquid, meant to provide cooling. They can be divided into the reusable type, which works as a thermal mass and requires freezing, or the instant type, which cools itself down using chemicals but can only be used once. The instant type is generally limited to medical use as a cold compress to alleviate the pain of minor injuries, while the reusable type is both used as a cold compress and to keep food cool in portable coolers or in insulated shipping containers to keep products cool during transport. Reusable packs To be prepared for use, the pack is first placed in a freezer. Both ice and other non-toxic refrigerants (mostly water) can absorb a considerable amount of heat before they warm above .` Ice packs are used in coolers to keep perishable foods (especially meats, dairy products, eggs, etc.) below the danger zone when outside a refrigerator or freezer, and to keep drinks pleasantly cool. The amount of ice needed varies with the amount of food, its initial temperature, the thermal insulation of the cooler, and the ambient temperature and exposure to direct sunlight. Ice initially well below freezing temperature will last a little longer. Water has a much higher latent heat of fusion than most substances, and a melting temperature which is convenient and easily attained with, for example, a household freezer. Additives to improve the properties of water are often used. For example, substances can be added to prevent bacterial growth in the pack, or to prevent the water from solidifying so it remains a thick gel throughout use. Gel packs are often made of non-toxic materials that will remain a slow-flowing gel, and therefore will not spill easily or cause contamination if the container breaks. Gel packs may be made by adding hydroxyethyl cellulose, sodium polyacrylate,Super absorbent polymerSAP or vinyl-coated silica gel. Hot-or-cold packs Hot-or-cold packs are ice packs tha
https://en.wikipedia.org/wiki/Medoid	Medoids are representative objects of a data set or a cluster within a data set whose sum of dissimilarities to all the objects in the cluster is minimal. Medoids are similar in concept to means or centroids, but medoids are always restricted to be members of the data set. Medoids are most commonly used on data when a mean or centroid cannot be defined, such as graphs. They are also used in contexts where the centroid is not representative of the dataset like in images, 3-D trajectories and gene expression (where while the data is sparse the medoid need not be). These are also of interest while wanting to find a representative using some distance other than squared euclidean distance (for instance in movie-ratings). For some data sets there may be more than one medoid, as with medians. A common application of the medoid is the k-medoids clustering algorithm, which is similar to the k-means algorithm but works when a mean or centroid is not definable. This algorithm basically works as follows. First, a set of medoids is chosen at random. Second, the distances to the other points are computed. Third, data are clustered according to the medoid they are most similar to. Fourth, the medoid set is optimized via an iterative process. Note that a medoid is not equivalent to a median, a geometric median, or centroid. A median is only defined on 1-dimensional data, and it only minimizes dissimilarity to other points for metrics induced by a norm (such as the Manhattan distance or Euclidean distance). A geometric median is defined in any dimension, but unlike a medoid, it is not necessarily a point from within the original dataset. Definition Let be a set of points in a space with a distance function d. Medoid is defined as Clustering with medoids Medoids are a popular replacement for the cluster mean when the distance function is not (squared) Euclidean distance, or not even a metric (as the medoid does not require the triangle inequality). When partitioning the d
https://en.wikipedia.org/wiki/JAUS	Joint Architecture for Unmanned Systems (JAUS), formerly known as Joint Architecture for Unmanned Ground Systems (JAUGS), was originally an initiative started in 1998 by the United States Department of Defense to develop an open architecture for the domain of unmanned systems. In order to ensure that the component architecture is applicable to the entire domain of current and future unmanned systems, it is built on five principles: vehicle platform independence, mission isolation, computer hardware independence, technology independence, and operator use independence. The JAUS Reference Architecture, which is no longer being maintained, is a component based message passing architecture that defines a data format and methods of communication between computing nodes. The architecture dictates a hierarchical system built up of subsystems, nodes and components, and contains a strictly defined message set to support interoperability. Significant portions of the architecture, including the definitions for subsystem, node and component, have been loosely defined in order to accommodate for the five principles on which it is based. The architecture has migrated from the JAUS Working Group, which was composed of individuals from the government, industry and academia, to the Society of Automotive Engineers, Aerospace Division, Avionics Systems Division. The AS4, Unmanned Systems Technical Committee now maintains and advances the set of standards. The following standards have been migrated from the JAUS Reference Architecture to a services based framework: AS5669, JAUS Transport Standard.Defines packet construction addressing transport concerns including header compression, source/destination addressing, TCP, UDP and Serial links. AS5669 defines the format of a JAUS message as it flows between systems in an Ethernet (TCP and UDP) or serial data link. AS5710, JAUS Core Service Set.Establishes a common set of services for distributed systems communication and coordination.
https://en.wikipedia.org/wiki/Admissible%20numbering	In computability theory, admissible numberings are enumerations (numberings) of the set of partial computable functions that can be converted to and from the standard numbering. These numberings are also called acceptable numberings and acceptable programming systems. Rogers' equivalence theorem shows that all acceptable programming systems are equivalent to each other in the formal sense of numbering theory. Definition The formalization of computability theory by Kleene led to a particular universal partial computable function Ψ(e, x) defined using the T predicate. This function is universal in the sense that it is partial computable, and for any partial computable function f there is an e such that, for all x, f(x) = Ψ(e,x), where the equality means that either both sides are undefined or both are defined and are equal. It is common to write ψe(x) for Ψ(e,x); thus the sequence ψ0, ψ1, ... is an enumeration of all partial computable functions. Such enumerations are formally called computable numberings of the partial computable functions. An arbitrary numbering η of partial functions is defined to be an admissible numbering if: The function H(e,x) = ηe(x) is a partial computable function. There is a total computable function f such that, for all e, ηe = ψf(e). There is a total computable function g such that, for all e, ψe = ηg(e). Here, the first bullet requires the numbering to be computable; the second requires that any index for the numbering η can be converted effectively to an index to the numbering ψ; and the third requires that any index for the numbering ψ can be effectively converted to an index for the numbering η. Rogers' equivalence theorem Hartley Rogers, Jr. showed that a numbering η of the partial computable functions is admissible if and only if there is a total computable bijection p such that, for all e, ηe = ψp(e) (Soare 1987:25). See also Friedberg numbering References Y.L. Ershov (1999), "Theory of numberings", Handbook of Co
https://en.wikipedia.org/wiki/Coal%20pollution%20mitigation	Coal Pollution Mitigation, sometimes also known as Clean Coal, is a series of systems and technologies that seek to mitigate (reduce harmful or unpleasant chemicals) health and environmental impact of coal; in particular air pollution from coal-fired power stations, and from coal burnt by heavy industry. Clean Coal primarily focuses on removing sulfur dioxide (SO2) and nitrogen oxides (NOx), the most important gasses which cause acid rain; and particulates which cause visible air pollution, illness, and premature deaths. It also reduces fly ash and reduces emissions of radioactive materials. Mercury emissions can be reduced up to 95%. Capturing carbon dioxide emissions from coal is also being pursued. Description When you burn coal, you release various chemicals into the air such as; Mercury, lead and other heavy metals, sulfur dioxide (SO2) and nitrogen oxides (NOx), which contributes to acid rain and respiratory illnesses, particulates, which contributes to smog, haze and respiratory illness as well and lung disease, carbon dioxide (CO2) (which is the primary greenhouse gas produce from burning fossil fuels), and finally radioactive materials, such as uranium for the coal. Coal pollution mitigation is a series of systems and technologies that seek to mitigate the health and environmental impact of coal; in particular air pollution from coal-fired power stand from coal burnt by heavy industry. Primarily focuses on sulfur dioxide (SO2) and nitrogen oxides (NOx), the most important gasses which cause acid rain; and particulates which cause visible air pollution, illness and premature deaths. SO2 can be removed by flue-gas desulfurization and NO2 by selective catalytic reduction (SCR). Particulates can be removed with electrostatic precipitators. Although perhaps less efficient, wet scrubbers can remove both gasses and particulates. Reducing fly ash reduces emissions of radioactive materials. Mercury emissions can be reduced up to 95%. Capturing carbon d
https://en.wikipedia.org/wiki/Clone%20tool	The clone tool, as it is known in Adobe Photoshop, Inkscape, GIMP, and Corel PhotoPaint, is used in digital image editing to replace information for one part of a picture with information from another part. In other image editing software, its equivalent is sometimes called a rubber stamp tool or a clone brush. Applications A typical use for the tool is in – more colloquially, "airbrushing" or "photoshopping" out an unwanted part of the image. If a part of an image is removed simply by cutting it out, then a hole is left in the background. The Clone tool can fill in this hole convincingly with a copy of the existing background from elsewhere in the image. A common use for this tool is to retouch skin, particularly in portraits, to remove blemishes and make skin tones more even. Cloning can also be used to remove other unwanted elements, such as telephone wires, an unwanted bird in the sky, and the like. A more automated method of object removal uses texture synthesis to fill in gaps. Of these, patch-based texture synthesis or "image quilting" is essentially an automated application of the clone tool, choosing the optimal source area so as to patch over with a minimal seam. In some cases, the undesired object is mixed with the remainder of the image, and a simple circular brush, even with feathering, would not work. For these cases, some programs allow an object to be selected by color/outline so other areas are not affected. Other programs allow edge/color sensitive brushes to deal with such objects. Healing tool A similar tool is the healing tool, which occurs in variants such as the healing brush or spot healing tool. These incorporate the existing texture, rather than painting it over. See also Inpainting Seam carving References External links GIMP manual: 3.10. Clone Image processing
https://en.wikipedia.org/wiki/Tetrameric%20protein	A tetrameric protein is a protein with a quaternary structure of four subunits (tetrameric). Homotetramers have four identical subunits (such as glutathione S-transferase), and heterotetramers are complexes of different subunits. A tetramer can be assembled as dimer of dimers with two homodimer subunits (such as sorbitol dehydrogenase), or two heterodimer subunits (such as hemoglobin). Subunit interactions in tetramers The interactions between subunits forming a tetramer is primarily determined by non covalent interaction. Hydrophobic effects, hydrogen bonds and electrostatic interactions are the primary sources for this binding process between subunits. For homotetrameric proteins such as Sorbitol dehydrogenase (SDH), the structure is believed to have evolved going from a monomeric to a dimeric and finally a tetrameric structure in evolution. The binding process in SDH and many other tetrameric enzymes can be described by the gain in free energy which can be determined from the rate of association and dissociation. The following image shows the assembly of the four subunits (A,B,C and D) in SDH. Hydrogen bonds between subunits Hydrogen bonding networks between subunits has been shown to be important for the stability of the tetrameric quaternary protein structure. For example, a study of SDH which used diverse methods such as protein sequence alignments, structural comparisons, energy calculations, gel filtration experiments and enzyme kinetics experiments, could reveal an important hydrogen bonding network which stabilizes the tetrameric quaternary structure in mammalian SDH. Tetramers in immunology In immunology, MHC tetramers can be used in tetramer assays, to quantify numbers of antigen-specific T cells (especially CD8+ T cells). MHC tetramers are based on recombinant class I molecules that, through the action of bacterial BirA, have been biotinylated. These molecules are folded with the peptide of interest and β2M and tetramerized by a fluorescently l
https://en.wikipedia.org/wiki/Redaction	Redaction or sanitization is the process of removing sensitive information from a document so that it may be distributed to a broader audience. It is intended to allow the selective disclosure of information. Typically, the result is a document that is suitable for publication or for dissemination to others rather than the intended audience of the original document. When the intent is secrecy protection, such as in dealing with classified information, redaction attempts to reduce the document's classification level, possibly yielding an unclassified document. When the intent is privacy protection, it is often called data anonymization. Originally, the term sanitization was applied to printed documents; it has since been extended to apply to computer files and the problem of data remanence. Government secrecy In the context of government documents, redaction (also called sanitization) generally refers more specifically to the process of removing sensitive or classified information from a document prior to its publication, during declassification. Secure document redaction techniques Redacting confidential material from a paper document before its public release involves overwriting portions of text with a wide black pen, followed by photocopying the result—the obscured text may be recoverable from the original. Alternatively opaque "cover up tape" or "redaction tape", opaque, removable adhesive tape in various widths, may be applied before photocopying. This is a simple process with only minor security risks. For example, if the black pen or tape is not wide enough, careful examination of the resulting photocopy may still reveal partial information about the text, such as the difference between short and tall letters. The exact length of the removed text also remains recognizable, which may help in guessing plausible wordings for shorter redacted sections. Where computer-generated proportional fonts were used, even more information can leak out of the redacted s
https://en.wikipedia.org/wiki/Penultimate%20hop%20popping	Penultimate hop popping (PHP) is a function performed by certain routers in an MPLS enabled network. It refers to the process whereby the outermost label of an MPLS tagged packet is removed by a label switch router (LSR) before the packet is passed to an adjacent label edge router (LER). The benefit is that the LSR has to do a label lookup anyway and it doesn't make a difference whether this results in a label swap or pop. However, for the LER this saves one cycle of label lookup. The process is important in a Layer 3 MPLS VPN () environment as it reduces the load on the LER. If this process didn't happen, the LER would have to perform at least 2 label lookups: The outer label, identifying that the packet was destined to have its label stripped on this router. The inner label, to identify which Virtual Routing and Forwarding (VRF) instance to use for the subsequent IP routing lookup. In large, loaded networks the additional time required for second label lookup can make a difference in the overall forwarding performance and reduce buffering. PHP functionality is achieved by the LER advertising a label with a value of 3 to its neighbours. This label is defined as "implicit-null" and informs the neighbouring LSR(s) to perform PHP. External links What Is PHP (Penultimate Hop Popping) MPLS - Penultimate Hop Popping MPLS PHP Lab MPLS networking
https://en.wikipedia.org/wiki/Pathfinding	Pathfinding or pathing is the plotting, by a computer application, of the shortest route between two points. It is a more practical variant on solving mazes. This field of research is based heavily on Dijkstra's algorithm for finding the shortest path on a weighted graph. Pathfinding is closely related to the shortest path problem, within graph theory, which examines how to identify the path that best meets some criteria (shortest, cheapest, fastest, etc) between two points in a large network. Algorithms At its core, a pathfinding method searches a graph by starting at one vertex and exploring adjacent nodes until the destination node is reached, generally with the intent of finding the cheapest route. Although graph searching methods such as a breadth-first search would find a route if given enough time, other methods, which "explore" the graph, would tend to reach the destination sooner. An analogy would be a person walking across a room; rather than examining every possible route in advance, the person would generally walk in the direction of the destination and only deviate from the path to avoid an obstruction, and make deviations as minor as possible. Two primary problems of pathfinding are (1) to find a path between two nodes in a graph; and (2) the shortest path problem—to find the optimal shortest path. Basic algorithms such as breadth-first and depth-first search address the first problem by exhausting all possibilities; starting from the given node, they iterate over all potential paths until they reach the destination node. These algorithms run in , or linear time, where V is the number of vertices, and E is the number of edges between vertices. The more complicated problem is finding the optimal path. The exhaustive approach in this case is known as the Bellman–Ford algorithm, which yields a time complexity of , or quadratic time. However, it is not necessary to examine all possible paths to find the optimal one. Algorithms such as A* and Dijkstra'
https://en.wikipedia.org/wiki/Criticality%20matrix	In operations research and engineering, a criticality matrix is a representation (often graphical) of failure modes along with their probabilities and severities. Example For example, an aircraft might have the following matrix: Industrial engineering
https://en.wikipedia.org/wiki/Passive%20dynamics	Passive dynamics refers to the dynamical behavior of actuators, robots, or organisms when not drawing energy from a supply (e.g., batteries, fuel, ATP). Depending on the application, considering or altering the passive dynamics of a powered system can have drastic effects on performance, particularly energy economy, stability, and task bandwidth. Devices using no power source are considered "passive", and their behavior is fully described by their passive dynamics. In some fields of robotics (legged robotics in particular), design and more relaxed control of passive dynamics has become a complementary (or even alternative) approach to joint-positioning control methods developed through the 20th century. Additionally, the passive dynamics of animals have been of interest to biomechanists and integrative biologists, as these dynamics often underlie biological motions and couple with neuromechanical control. Particularly relevant fields for investigating and engineering passive dynamics include legged locomotion and manipulation. History The term and its principles were developed by Tad McGeer in the late 1980s. While at Simon Fraser University in Burnaby, British Columbia, McGeer showed that a human-like frame can walk itself down a slope without requiring muscles or motors. Unlike traditional robots, which expend energy by using motors to control every motion, McGeer's early passive-dynamic machines relied only on gravity and the natural swinging of their limbs to move forward down a slope. Models The original model for passive dynamics is based on human and animal leg motions. Completely actuated systems, such as the legs of the Honda Asimo robot, are not very efficient because each joint has a motor and control assembly. Human-like gaits are far more efficient because movement is sustained by the natural swing of the legs instead of motors placed at each joint. Tad McGeer's 1990 paper "Passive Walking with Knees" provides an excellent overview on the adv
https://en.wikipedia.org/wiki/Euler%20diagram	An Euler diagram (, ) is a diagrammatic means of representing sets and their relationships. They are particularly useful for explaining complex hierarchies and overlapping definitions. They are similar to another set diagramming technique, Venn diagrams. Unlike Venn diagrams, which show all possible relations between different sets, the Euler diagram shows only relevant relationships. The first use of "Eulerian circles" is commonly attributed to Swiss mathematician Leonhard Euler (1707–1783). In the United States, both Venn and Euler diagrams were incorporated as part of instruction in set theory as part of the new math movement of the 1960s. Since then, they have also been adopted by other curriculum fields such as reading as well as organizations and businesses. Euler diagrams consist of simple closed shapes in a two-dimensional plane that each depict a set or category. How or whether these shapes overlap demonstrates the relationships between the sets. Each curve divides the plane into two regions or "zones": the interior, which symbolically represents the elements of the set, and the exterior, which represents all elements that are not members of the set. Curves that do not overlap represent disjoint sets, which have no elements in common. Two curves that overlap represent sets that intersect, that have common elements; the zone inside both curves represents the set of elements common to both sets (the intersection of the sets). A curve completely within the interior of another is a subset of it. Venn diagrams are a more restrictive form of Euler diagrams. A Venn diagram must contain all 2n logically possible zones of overlap between its n curves, representing all combinations of inclusion/exclusion of its constituent sets. Regions not part of the set are indicated by coloring them black, in contrast to Euler diagrams, where membership in the set is indicated by overlap as well as color. History As shown in the illustration to the right, Sir William
https://en.wikipedia.org/wiki/False%20nearest%20neighbor%20algorithm	Within abstract algebra, the false nearest neighbor algorithm is an algorithm for estimating the embedding dimension. The concept was proposed by Kennel et al. (1992). The main idea is to examine how the number of neighbors of a point along a signal trajectory change with increasing embedding dimension. In too low an embedding dimension, many of the neighbors will be false, but in an appropriate embedding dimension or higher, the neighbors are real. With increasing dimension, the false neighbors will no longer be neighbors. Therefore, by examining how the number of neighbors change as a function of dimension, an appropriate embedding can be determined. See also Commutative ring Local ring Nearest neighbor Time series References Statistical algorithms Dynamical systems Nonlinear time series analysis
https://en.wikipedia.org/wiki/Potentiostat	A potentiostat is the electronic hardware required to control a three electrode cell and run most electroanalytical experiments. A Bipotentiostat and polypotentiostat are potentiostats capable of controlling two working electrodes and more than two working electrodes, respectively. The system functions by maintaining the potential of the working electrode at a constant level with respect to the reference electrode by adjusting the current at an auxiliary electrode. The heart of the different potentiostatic electronic circuits is an operational amplifier (op amp). It consists of an electric circuit which is usually described in terms of simple op amps. Primary use This equipment is fundamental to modern electrochemical studies using three electrode systems for investigations of reaction mechanisms related to redox chemistry and other chemical phenomena. The dimensions of the resulting data depend on the experiment. In voltammetry, electric current in amps is plotted against electric potential in voltage. In a bulk electrolysis total coulombs passed (total electric charge) is plotted against time in seconds even though the experiment measures electric current (amperes) over time. This is done to show that the experiment is approaching an expected number of coulombs. Most early potentiostats could function independently, providing data output through a physical data trace. Modern potentiostats are designed to interface with a personal computer and operate through a dedicated software package. The automated software allows the user rapidly to shift between experiments and experimental conditions. The computer allows data to be stored and analyzed more effectively, rapidly, and accurately than the earlier standalone devices. Basic relationships A potentiostat is a control and measuring device. It comprises an electric circuit which controls the potential across the cell by sensing changes in its resistance, varying accordingly the current supplied
https://en.wikipedia.org/wiki/Immunoelectrophoresis	Immunoelectrophoresis is a general name for a number of biochemical methods for separation and characterization of proteins based on electrophoresis and reaction with antibodies. All variants of immunoelectrophoresis require immunoglobulins, also known as antibodies, reacting with the proteins to be separated or characterized. The methods were developed and used extensively during the second half of the 20th century. In somewhat chronological order: Immunoelectrophoretic analysis (one-dimensional immunoelectrophoresis ad modum Grabar), crossed immunoelectrophoresis (two-dimensional quantitative immunoelectrophoresis ad modum Clarke and Freeman or ad modum Laurell), rocket-immunoelectrophoresis (one-dimensional quantitative immunoelectrophoresis ad modum Laurell), fused rocket immunoelectrophoresis ad modum Svendsen and Harboe, affinity immunoelectrophoresis ad modum Bøg-Hansen. Methods Immunoelectrophoresis is a general term describing many combinations of the principles of electrophoresis and reaction of antibodies, also known as immunodiffusion. Agarose as 1% gel slabs of about 1 mm thickness buffered at high pH (around 8.6) is traditionally preferred for electrophoresis and the reaction with antibodies. The agarose was chosen as the gel matrix because it has large pores allowing free passage and separation of proteins but provides an anchor for the immunoprecipitates of protein and specific antibodies. The high pH was chosen because antibodies are practically immobile at high pH. Electrophoresis equipment with a horizontal cooling plate was normally recommended for the electrophoresis. Immunoprecipitates are visible in the wet agarose gel, but are stained with protein stains like Coomassie brilliant blue in the dried gel. In contrast to SDS-gel electrophoresis, the electrophoresis in agarose allows native conditions, preserving the native structure and activities of the proteins under investigation, therefore immunoelectrophoresis allows characterization of e
https://en.wikipedia.org/wiki/Cell%20migration	Cell migration is a central process in the development and maintenance of multicellular organisms. Tissue formation during embryonic development, wound healing and immune responses all require the orchestrated movement of cells in particular directions to specific locations. Cells often migrate in response to specific external signals, including chemical signals and mechanical signals. Errors during this process have serious consequences, including intellectual disability, vascular disease, tumor formation and metastasis. An understanding of the mechanism by which cells migrate may lead to the development of novel therapeutic strategies for controlling, for example, invasive tumour cells. Due to the highly viscous environment (low Reynolds number), cells need to continuously produce forces in order to move. Cells achieve active movement by very different mechanisms. Many less complex prokaryotic organisms (and sperm cells) use flagella or cilia to propel themselves. Eukaryotic cell migration typically is far more complex and can consist of combinations of different migration mechanisms. It generally involves drastic changes in cell shape which are driven by the cytoskeleton. Two very distinct migration scenarios are crawling motion (most commonly studied) and blebbing motility. A paradigmatic example of crawling motion is the case of fish epidermal keratocytes, which have been extensively used in research and teaching. Cell migration studies The migration of cultured cells attached to a surface or in 3D is commonly studied using microscopy. As cell movement is very slow, a few µm/minute, time-lapse microscopy videos are recorded of the migrating cells to speed up the movement. Such videos (Figure 1) reveal that the leading cell front is very active, with a characteristic behavior of successive contractions and expansions. It is generally accepted that the leading front is the main motor that pulls the cell forward. Common features The processes underlying mammal
https://en.wikipedia.org/wiki/TwoOStwo	twoOStwo was a commercial software product developed by Parallels Software Studio (prior to its acquisition by SWsoft). The workstation software consisted of a virtual machine suite for Intel x86-compatible computers which allowed the creation and execution of multiple x86 virtual computers simultaneously. Each virtual machine instance could execute its own guest operating system including Windows, Linux, OS/2 and BSD variants. Description The computer and operating system instance that executes the twoOStwo process is referred to as the host machine. Instances of operating systems running inside a virtual machine are referred to as guest virtual machines. Like an emulator, twoOStwo provides a completely virtualized set of hardware to the guest operating system; for example, irrespective of make and model of the physical network adapter, the guest machine will see a Novell/Eagle NE2000 or Realtek RTL8029(AS) network adapter. twoOStwo virtualizes all devices within the virtual environment, including the video adapter, network adapter, and hard disk adapters. It also provides pass-through drivers for serial and parallel devices. Because all guest virtual machines use the same hardware drivers irrespective of the actual hardware on the host computer, virtual machine instances are highly portable between computers. For example, a running virtual machine can be stopped, copied to another physical computer, and started. Implementation Conventional emulators like Bochs emulate the microprocessor, executing each guest CPU instruction by calling a software subroutine on the host machine that simulates the function of that CPU instruction. This level of abstraction allows the guest machine to run on host machines with a different type of microprocessor, but is also very slow. A more efficient approach consists in software debugger technique. Some parts of the code are executed natively on the real processor; on 'bad' instructions, there are software interrupts that break
https://en.wikipedia.org/wiki/Cockcroft%E2%80%93Walton%20generator	The Cockcroft–Walton (CW) generator, or multiplier, is an electric circuit that generates a high DC voltage from a low-voltage AC or pulsing DC input. It was named after the British and Irish physicists John Douglas Cockcroft and Ernest Thomas Sinton Walton, who in 1932 used this circuit design to power their particle accelerator, performing the first artificial nuclear disintegration in history. They used this voltage multiplier cascade for most of their research, which in 1951 won them the Nobel Prize in Physics for "Transmutation of atomic nuclei by artificially accelerated atomic particles". The circuit was developed in 1919, by Heinrich Greinacher, a Swiss physicist. For this reason, this doubler cascade is sometimes also referred to as the Greinacher multiplier. Cockcroft–Walton circuits are still used in particle accelerators. They also are used in everyday electronic devices that require high voltages, such as X-ray machines, microwave ovens and photocopiers. Operation The CW generator is a voltage multiplier that converts AC or pulsing DC electrical power from a low voltage level to a higher DC voltage level. It is made up of a voltage multiplier ladder network of capacitors and diodes to generate high voltages. Unlike transformers, this method eliminates the requirement for the heavy core and the bulk of insulation/potting required. Using only capacitors and diodes, these voltage multipliers can step up relatively low voltages to extremely high values, while at the same time being far lighter and cheaper than transformers. The biggest advantage of such circuits is that the voltage across each stage of the cascade is equal to only twice the peak input voltage in a half-wave rectifier. In a full-wave rectifier it is three times the input voltage. It has the advantage of requiring relatively low-cost components and being easy to insulate. One can also tap the output from any stage, like in a multi-tapped transformer. To understand the circuit operat
https://en.wikipedia.org/wiki/Windows%20Communication%20Foundation	The Windows Communication Foundation (WCF), previously known as Indigo, is a free and open-source runtime and a set of APIs in the .NET Framework for building connected, service-oriented applications. .NET Core 1.0, released 2016, did not support WCF server side code. WCF support was added to the platform with support for .NET Core 3.1, .NET 5, and .NET 6 in 2022. The architecture WCF is a tool often used to implement and deploy a service-oriented architecture (SOA). It is designed using service-oriented architecture principles to support distributed computing where services have remote consumers. Clients can consume multiple services; services can be consumed by multiple clients. Services are loosely coupled to each other. Services typically have a WSDL interface (Web Services Description Language) that any WCF client can use to consume the service, regardless of which platform the service is hosted on. WCF implements many advanced Web services (WS) standards such as WS-Addressing, WS-ReliableMessaging and WS-Security. With the release of .NET Framework 4.0, WCF also provides RSS Syndication Services, WS-Discovery, routing and better support for REST services. Endpoints A WCF client connects to a WCF service via an endpoint. Each service exposes its contract via one or more endpoints. An endpoint has an address (which is a URL specifying where the endpoint can be accessed) and binding properties that specify how the data will be transferred. The mnemonic "ABC" can be used to remember address/binding/contract. Binding specifies what communication protocols are used to access the service, whether security mechanisms are to be used, and the like. WCF includes predefined bindings for most common communication protocols such as SOAP over HTTP, SOAP over TCP, and SOAP over Message Queues, etc. Interaction between WCF endpoint and client is done using a SOAP envelope. SOAP envelopes are in simple XML form, which makes WCF platform-independent. When a client wants to
https://en.wikipedia.org/wiki/SVISTA	SVISTA (Serenity Virtual Station) is a former commercial virtual machine software product marketed by Serenity Systems International. Windows, OS/2, Linux and FreeBSD hosted versions were available. This product is no longer available nor supported. Description SVISTA was developed under contract with Parallels Software Studio and was based on its existing TwoOStwo software, although the OS/2 and FreeBSD hosted versions were specific to SVISTA. Providing a virtualization product was initially part of Serenity's strategy for marketing its eComStation operating system. When the OS/2 port of Connectix VirtualPC was discontinued following the acquisition of its creator by Microsoft, Serenity contracted Parallels to develop SVISTA as an alternative. A beta program was launched in the spring of 2004, with a general availability release in October of that year. However, the product was discontinued shortly afterwards following the acquisition of Parallels by SWsoft. According to Bob St. John of Serenity Systems, SWsoft was not interested in continuing the development of SVISTA, and withdrew from the OEM contract. Although Serenity briefly expressed interest in finding another solution for an OS/2 hosted virtualization product, it was eventually deemed impractical due to increased competition in the consumer market from Microsoft and VMware. The former product website currently indicates that SVISTA is no longer available, and suggests Virtual Bridges and VirtualBox as possible third-party alternatives. Issues When using SVISTA instances in an environment where MAC addresses are used as unique identifiers (UID), it is advisable to manually configure the MAC address for each virtual machine to ensure each is actually unique. One example of such an environment is one in which MAC security is enabled on switches and another example is an environment in which Altiris products are used (if configured to use the MAC address as the UID). If you are in such a situation, si
https://en.wikipedia.org/wiki/Box%20truss	A box truss is a structure composed of three or more chords connected by transverse and/or diagonal structural elements. Application Box trusses are commonly used in certain types of aircraft fuselages, electric power pylons, large radio antennas, and many bridge structures. (For various truss arrangements used see truss bridge.) By using what are in effect stiff panels in a cylindrical arrangement the resulting structure can have a high resistance to axial torsion (twisting along its long axis) and a higher resistance to buckling in its highly loaded sides. When finished as an open structure the truss will be less subject to wind drag and to aeroelastic effects than would a completely enclosed structure. Structural system

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