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https://en.wikipedia.org/wiki/Interface%20%28computing%29 | In computing, an interface is a shared boundary across which two or more separate components of a computer system exchange information. The exchange can be between software, computer hardware, peripheral devices, humans, and combinations of these. Some computer hardware devices, such as a touchscreen, can both send and receive data through the interface, while others such as a mouse or microphone may only provide an interface to send data to a given system.
Hardware interfaces
Hardware interfaces exist in many components, such as the various buses, storage devices, other I/O devices, etc. A hardware interface is described by the mechanical, electrical, and logical signals at the interface and the protocol for sequencing them (sometimes called signaling). A standard interface, such as SCSI, decouples the design and introduction of computing hardware, such as I/O devices, from the design and introduction of other components of a computing system, thereby allowing users and manufacturers great flexibility in the implementation of computing systems. Hardware interfaces can be parallel with several electrical connections carrying parts of the data simultaneously or serial where data are sent one bit at a time.
Software interfaces
A software interface may refer to a wide range of different types of interface at different "levels". For example, an operating system may interface with pieces of hardware. Applications or programs running on the operating system may need to interact via data streams, filters, and pipelines. In object oriented programs, objects within an application may need to interact via methods.
In practice
A key principle of design is to prohibit access to all resources by default, allowing access only through well-defined entry points, i.e., interfaces. Software interfaces provide access to computer resources (such as memory, CPU, storage, etc.) of the underlying computer system; direct access (i.e., not through well-designed interfaces) to such r |
https://en.wikipedia.org/wiki/Eugenio%20Calabi | Eugenio Calabi (May 11, 1923 – September 25, 2023) was an Italian-born American mathematician and the Thomas A. Scott Professor of Mathematics at the University of Pennsylvania, specializing in differential geometry, partial differential equations and their applications.
Early life and education
Calabi was born in Milan, Italy on May 11, 1923, into a Jewish family. His sister was the journalist Tullia Zevi Calabi. In 1938, the family left Italy because of the racial laws, and in 1939 arrived in the United States.
In the fall of 1939, aged only 16, Calabi enrolled at the Massachusetts Institute of Technology, studying chemical engineering. His studies were interrupted when he was drafted in the US military in 1943 and served during World War II. Upon his discharge in 1946, Calabi was able to finish his bachelor's degree under the G.I. Bill, and was a Putnam Fellow. He received a master's degree in mathematics from the University of Illinois Urbana-Champaign in 1947 and his PhD in mathematics from Princeton University in 1950. His doctoral dissertation, titled "Isometric complex analytic imbedding of Kähler manifolds", was done under the supervision of Salomon Bochner.
Academic career
From 1951 to 1955 he was an assistant professor at Louisiana State University, and he moved to the University of Minnesota in 1955, where he become a full professor in 1960. In 1964, Calabi joined the mathematics faculty at the University of Pennsylvania. Following the retirement of Hans Rademacher, he was appointed to the Thomas A. Scott Professorship of Mathematics at the University of Pennsylvania in 1968. In 1994, Calabi assumed emeritus status, and in 2014 the university awarded him an honorary doctorate of science.
In 1982, Calabi was elected to the National Academy of Sciences. He won the Leroy P. Steele Prize from the American Mathematical Society in 1991, where his "fundamental work on global differential geometry, especially complex differential geometry" was cited as havi |
https://en.wikipedia.org/wiki/Interpretability | In mathematical logic, interpretability is a relation between formal theories that expresses the possibility of interpreting or translating one into the other.
Informal definition
Assume T and S are formal theories. Slightly simplified, T is said to be interpretable in S if and only if the language of T can be translated into the language of S in such a way that S proves the translation of every theorem of T. Of course, there are some natural conditions on admissible translations here, such as the necessity for a translation to preserve the logical structure of formulas.
This concept, together with weak interpretability, was introduced by Alfred Tarski in 1953. Three other related concepts are cointerpretability, logical tolerance, and cotolerance, introduced by Giorgi Japaridze in 1992–93.
See also
Interpretation (logic)
Interpretation (model theory)
Interpretability logic
References
Japaridze, G., and De Jongh, D. (1998) "The logic of provability" in Buss, S., ed., Handbook of Proof Theory. North-Holland: 476–546.
Alfred Tarski, Andrzej Mostowski, and Raphael Robinson (1953) Undecidable Theories. North-Holland.
Proof theory |
https://en.wikipedia.org/wiki/Cointerpretability | In mathematical logic, cointerpretability is a binary relation on formal theories: a formal theory T is cointerpretable in another such theory S, when the language of S can be translated into the language of T in such a way that S proves every formula whose translation is a theorem of T. The "translation" here is required to preserve the logical structure of formulas.
This concept, in a sense dual to interpretability, was introduced by , who also proved that, for theories of Peano arithmetic and any stronger theories with effective axiomatizations, cointerpretability is equivalent to -conservativity.
See also
Cotolerance
Interpretability logic.
Tolerance (in logic)
References
.
.
Mathematical relations
Mathematical logic |
https://en.wikipedia.org/wiki/Tolerant%20sequence | In mathematical logic, a tolerant sequence is a sequence
,...,
of formal theories such that there are consistent extensions
,...,
of these theories with each interpretable in . Tolerance naturally generalizes from sequences of theories to trees of theories. Weak interpretability can be shown to be a special, binary case of tolerance.
This concept, together with its dual concept of cotolerance, was introduced by Japaridze in 1992, who also proved that, for Peano arithmetic and any stronger theories with effective axiomatizations, tolerance is equivalent to -consistency.
See also
Interpretability
Cointerpretability
Interpretability logic
References
G. Japaridze, The logic of linear tolerance. Studia Logica 51 (1992), pp. 249–277.
G. Japaridze, A generalized notion of weak interpretability and the corresponding logic. Annals of Pure and Applied Logic 61 (1993), pp. 113–160.
G. Japaridze and D. de Jongh, The logic of provability. Handbook of Proof Theory. S. Buss, ed. Elsevier, 1998, pp. 476–546.
Proof theory |
https://en.wikipedia.org/wiki/List%20of%20computer%20graphics%20and%20descriptive%20geometry%20topics | This is a list of computer graphics and descriptive geometry topics, by article name.
2D computer graphics
2D geometric model
3D computer graphics
3D projection
Alpha compositing
Anisotropic filtering
Anti-aliasing
Axis-aligned bounding box
Axonometric projection
Bézier curve
Bézier surface
Bicubic interpolation
Bilinear interpolation
Binary space partitioning
Bitmap graphics editor
Bounding volume
Bresenham's line algorithm
Bump mapping
Collision detection
Color space
Colour banding
Computational geometry
Computer animation
Computer-generated art
Computer painting
Convex hull
Curvilinear perspective
Cylindrical perspective
Data compression
Digital raster graphic
Dimetric projection
Distance fog
Dithering
Elevation
Engineering drawing
Flat shading
Flood fill
Geometric model
Geometric primitive
Global illumination
Gouraud shading
Graphical projection
Graphics suite
Heightfield
Hidden face removal
Hidden line removal
High-dynamic-range rendering
Isometric projection
Lathe (graphics)
Line drawing algorithm
Linear perspective
Mesh generation
Motion blur
Orthographic projection
Orthographic projection (geometry)
Orthogonal projection
Perspective (graphical)
Phong reflection model
Phong shading
Pixel shaders
Polygon (computer graphics)
Procedural surface
Projection
Projective geometry
Quadtree
Radiosity
Raster graphics
Raytracing
Rendering (computer graphics)
Reverse perspective
Scan line rendering
Scrolling
Technical drawing
Texture mapping
Trimetric projection
Vanishing point
Vector graphics
Vector graphics editor
Vertex shaders
Volume rendering
Voxel
See also
List of geometry topics
List of graphical methods
Computing-related lists
Mathematics-related lists |
https://en.wikipedia.org/wiki/Geometric%20topology | In mathematics, geometric topology is the study of manifolds and maps between them, particularly embeddings of one manifold into another.
History
Geometric topology as an area distinct from algebraic topology may be said to have originated in the 1935 classification of lens spaces by Reidemeister torsion, which required distinguishing spaces that are homotopy equivalent but not homeomorphic. This was the origin of simple homotopy theory. The use of the term geometric topology to describe these seems to have originated rather recently.
Differences between low-dimensional and high-dimensional topology
Manifolds differ radically in behavior in high and low dimension.
High-dimensional topology refers to manifolds of dimension 5 and above, or in relative terms, embeddings in codimension 3 and above. Low-dimensional topology is concerned with questions in dimensions up to 4, or embeddings in codimension up to 2.
Dimension 4 is special, in that in some respects (topologically), dimension 4 is high-dimensional, while in other respects (differentiably), dimension 4 is low-dimensional; this overlap yields phenomena exceptional to dimension 4, such as exotic differentiable structures on R4. Thus the topological classification of 4-manifolds is in principle tractable, and the key questions are: does a topological manifold admit a differentiable structure, and if so, how many? Notably, the smooth case of dimension 4 is the last open case of the generalized Poincaré conjecture; see Gluck twists.
The distinction is because surgery theory works in dimension 5 and above (in fact, in many cases, it works topologically in dimension 4, though this is very involved to prove), and thus the behavior of manifolds in dimension 5 and above may be studied using the surgery theory program. In dimension 4 and below (topologically, in dimension 3 and below), surgery theory does not work.
Indeed, one approach to discussing low-dimensional manifolds is to ask "what would surgery theory pred |
https://en.wikipedia.org/wiki/Radioactive%20contamination | Radioactive contamination, also called radiological pollution, is the deposition of, or presence of radioactive substances on surfaces or within solids, liquids, or gases (including the human body), where their presence is unintended or undesirable (from the International Atomic Energy Agency (IAEA) definition).
Such contamination presents a hazard because the radioactive decay of the contaminants produces ionizing radiation (namely alpha, beta, gamma rays and free neutrons). The degree of hazard is determined by the concentration of the contaminants, the energy of the radiation being emitted, the type of radiation, and the proximity of the contamination to organs of the body. It is important to be clear that the contamination gives rise to the radiation hazard, and the terms "radiation" and "contamination" are not interchangeable.
The sources of radioactive pollution can be classified into two groups: natural and man-made. Following an atmospheric nuclear weapon discharge or a nuclear reactor containment breach, the air, soil, people, plants, and animals in the vicinity will become contaminated by nuclear fuel and fission products. A spilled vial of radioactive material like uranyl nitrate may contaminate the floor and any rags used to wipe up the spill. Cases of widespread radioactive contamination include the Bikini Atoll, the Rocky Flats Plant in Colorado, the area near the Fukushima Daiichi nuclear disaster, the area near the Chernobyl disaster, and the area near the Mayak disaster.
Sources of contamination
The sources of radioactive pollution can be natural or man-made.
Radioactive contamination can be due to a variety of causes. It may occur due to the release of radioactive gases, liquids or particles. For example, if a radionuclide used in nuclear medicine is spilled (accidentally or, as in the case of the Goiânia accident, through ignorance), the material could be spread by people as they walk around.
Radioactive contamination may also be an inevitab |
https://en.wikipedia.org/wiki/PC%20Bruno | PC Bruno was a Polish–French–Spanish signals–intelligence station near Paris during World War II, from October 1939 until June 1940. Its function was decryption of cipher messages, most notably German messages enciphered on the Enigma machine.
PC Bruno worked in close cooperation with Britain's decryption center at Bletchley Park.
History
In the early 1930s, French military intelligence acquired operation manuals and sample messages for the German Enigma cipher machine. French intelligence officer Captain Gustave Bertrand supplied this material to Poland's Biuro Szyfrów ("Cipher Bureau"), which used it as part of their successful effort to break Enigma.
In July 1939 the Biuro Szyfrów gave French and British intelligence all their results. Both countries were expanding their decryption efforts in anticipation of war, and this continued after the war started in September 1939.
When Poland was overrun by Germany and the Soviet Union, the key staff of the Biuro Szyfrów were evacuated to Romania, and from there eventually reached France. On 20 October 1939 the Poles resumed work, hosted by French intelligence at PC Bruno.
PC Bruno was located in the Château de Vignolles in Gretz-Armainvilliers, some 40 kilometres southeast of Paris. It was headed by now-Major Bertrand. Its personnel included 15 Poles, 50 Frenchmen, and 7 anti-fascist Spaniards who worked on Spanish and Italian ciphers. The Polish group was led by Lt. Col. Gwido Langer and included the mathematicians who had been breaking Enigma for nearly seven years since December 1932: Marian Rejewski, Jerzy Różycki, and Henryk Zygalski. The Spanish team (Equipo D – Team D) was led by Faustino A.V. Camazón, who was aware of the use of the Enigma machine by German forces during the Spanish Civil War.
As late as 3–7 December 1939, when Lt. Col. Langer and French Air Force Capt. Henri Braquenié visited London and Bletchley Park, the British asked that the Polish cryptologists be made available to them in Britain. |
https://en.wikipedia.org/wiki/S-matrix | In physics, the S-matrix or scattering matrix relates the initial state and the final state of a physical system undergoing a scattering process. It is used in quantum mechanics, scattering theory and quantum field theory (QFT).
More formally, in the context of QFT, the S-matrix is defined as the unitary matrix connecting sets of asymptotically free particle states (the in-states and the out-states) in the Hilbert space of physical states. A multi-particle state is said to be free (non-interacting) if it transforms under Lorentz transformations as a tensor product, or direct product in physics parlance, of one-particle states as prescribed by equation below. Asymptotically free then means that the state has this appearance in either the distant past or the distant future.
While the S-matrix may be defined for any background (spacetime) that is asymptotically solvable and has no event horizons, it has a simple form in the case of the Minkowski space. In this special case, the Hilbert space is a space of irreducible unitary representations of the inhomogeneous Lorentz group (the Poincaré group); the S-matrix is the evolution operator between (the distant past), and (the distant future). It is defined only in the limit of zero energy density (or infinite particle separation distance).
It can be shown that if a quantum field theory in Minkowski space has a mass gap, the state in the asymptotic past and in the asymptotic future are both described by Fock spaces.
History
The S-matrix was first introduced by John Archibald Wheeler in the 1937 paper "On the Mathematical Description of Light Nuclei by the Method of Resonating Group Structure". In this paper Wheeler introduced a scattering matrix – a unitary matrix of coefficients connecting "the asymptotic behaviour of an arbitrary particular solution [of the integral equations] with that of solutions of a standard form", but did not develop it fully.
In the 1940s, Werner Heisenberg independently developed and substa |
https://en.wikipedia.org/wiki/Moroccan%20Western%20Sahara%20Wall | The Moroccan Western Sahara Wall or the Berm, also called the Moroccan sand wall (), is an approximately berm running south to north through Western Sahara and the southwestern portion of Morocco. It separates the Moroccan-controlled areas (the Southern Provinces) on the west from the Polisario-controlled areas (Free Zone, nominally Sahrawi Arab Democratic Republic) on the east. The main function of the barriers is to exclude guerrilla fighters of the Polisario Front, who have sought Western Saharan independence since before Spain ended its colonial occupation in 1975, from the Moroccan-controlled western part of the territory.
According to maps from the United Nations Mission for the Referendum in Western Sahara (MINURSO) or the United Nations High Commissioner for Refugees (UNHCR), in some places the wall extends several kilometers into internationally recognized Mauritanian territory.
Names
The wall is also called the Western Sahara berm and the Western Sahara separation barrier.
Physical structure
The fortifications lie in uninhabited or very sparsely inhabited territory. They consist of sand and stone walls or berms about in height, with bunkers, fences, and landmines throughout. The barrier minebelt that runs along the structure is thought to be the longest continuous minefield in the world. Military bases, artillery posts and airfields dot the Moroccan-controlled side of the wall at regular intervals, and radar masts and other electronic surveillance equipment scan the areas in front of it.
The following is one observer's description of the berm from 2001:
In all, six lines of berms have been constructed. The main ("external") line of fortifications extends for about . It runs east from Guerguerat on the coast in the extreme south of Western Sahara near the Mauritanian town of Nouadhibou, closely parallelling the Mauritanian border for about , before turning north beyond Tichla. It then runs generally northeastward, leaving Guelta Zemmur and Smara, aga |
https://en.wikipedia.org/wiki/Galaga | is a 1981 fixed shooter arcade video game developed and published by Namco. In North America, it was released by Midway Manufacturing. It is the sequel to Galaxian (1979), Namco's first major video game hit in arcades. Controlling a starship, the player is tasked with destroying the Galaga forces in each stage while avoiding enemies and projectiles. Some enemies can capture a player's ship via a tractor beam, which can be rescued to transform the player into a "dual fighter" with additional firepower.
Shigeru Yokoyama led development with a small team. Initial planning took about two months to finish. Originally developed for the Namco Galaxian arcade board, it was instead shifted to a new system as suggested by Namco's Research and Development division. Inspiration for the dual fighter mechanic was taken from a film that Yokoyama had seen prior to development, where a ship was captured using a large circular beam. The project became immensely popular around the company, with Namco's president Masaya Nakamura even taking interest.
Although early location tests were unsuccessful, Galaga received critical acclaim and went on to become one of the most successful arcade games, routinely appearing on Japanese and American arcade charts through 1987. It is widely regarded as a classic of the golden age of arcade video games and one of the greatest video games of all time. Critics applauded its gameplay, innovation, addictive nature and improvements made over its predecessor. Several home ports were released for a multitude of platforms, including the MSX, Atari 7800 and Nintendo Entertainment System, alongside releases on digital distribution platforms such as Xbox Live Arcade. Galaga is also included in many Namco compilations. It was followed by a sequel in 1984, Gaplus.
Gameplay
Galaga is a fixed shooter. The player mans a lone starfighter at the bottom of the screen, which must prevent the Galaga forces from destroying all of mankind. The objective of each stage i |
https://en.wikipedia.org/wiki/WWHO | WWHO (channel 53) is a television station licensed to Chillicothe, Ohio, United States, serving the Columbus area as an affiliate of The CW. It is owned by Manhan Media, Inc., which maintains a local marketing agreement (LMA) with Sinclair Broadcast Group, owner of ABC/MyNetworkTV/Fox affiliate WSYX (channel 6), for the provision of certain services. Sinclair also operates TBD station WTTE (channel 28) under a separate LMA with Cunningham Broadcasting; however, Sinclair effectively owns WTTE as the majority of Cunningham's stock is owned by the family of deceased group founder Julian Smith. The stations share studios on Dublin Road in Grandview Heights (with a Columbus mailing address), while WWHO's transmitter is located in the Franklinton section of Columbus.
WWHO also served briefly as the default CW affiliate (on cable) for the Zanesville media market from March 2008 through early July 2008, after WHIZ-TV discontinued WBZV, its cable-only CW Plus affiliate. The CW Plus has since been reinstated to the Zanesville cable line-up via a Spectrum-provided cable-only CW Plus feed branded as "Zanesville CW 13" in the market, which has no connections to WHIZ-TV. WWHO served as the de facto over-the-air WB affiliate for the Dayton, Ohio, media market until 1999, when WBDT (then a primary Pax affiliate) joined The WB; which relegated Pax to a secondary affiliation. WWHO also provided UPN service to much of the Dayton market over the air until 2006, when The CW was launched.
History
The station began operating on August 31, 1987, as an independent station using the call letters WWAT, named after its owner, Wendell A. Triplett. It filled in a void created when future sister station WTTE joined Fox in 1986. The station originally operated from studios located on River Road (US 23) in Chillicothe. It operated a Columbus translator on W17AI channel 17 (now WDEM, which is still owned by Triplett) until 1992, when WWAT was added to many cable providers in the Columbus market d |
https://en.wikipedia.org/wiki/Adam%20Spencer | Adam Barrington Spencer (born 29 January 1969) is an Australian comedian, media personality and former radio presenter. He first came to fame when he won his round of the comedic talent search Raw Comedy in 1996. Soon thereafter, he began working at Triple J, on mid-dawn and drive shifts before hosting the Triple J Breakfast Show with Wil Anderson. He later hosted Breakfast on 702 ABC Sydney.
He is a patron of science-related events and programs, including the University of Sydney's Sleek Geeks Science Prize (category in the Eureka Prize). He collaborated with Karl Kruszelnicki for the long-running Sleek Geek Week tour (as part of National Science Week). He hosts events and panels, writes mathematical recreation books, and performs his own comedy at events around the country.
He is a supporter of the Australian rules football team, the Sydney Swans, and was declared their number one ticket holder for the 2016 season.
Early life
Born on 29 January 1969, in Sydney, Spencer grew up in the Hunters Hill/Gladesville area.
A few hours after birth, he had a seizure, and doctors found blood between his brain and scalp. Twice in the first two days of his life, a priest was called to give the last rites. Between the ages of three until about 11, Spencer underwent a series of operations by eye surgeon Fred Hollows. The deadening of the eyelid muscle led to permanent ptosis (drooping of the upper eyelid) and noticeable facial asymmetry. He later received a transplant from a donor (who had been in a motorcycle accident) in an operation, allowing him to "open" that eye.
His father Larry, died from prostate cancer in 2004. He has a brother and a sister.
Spencer attended Boronia Park Public School, where his favourite teacher, Ms Russell, encouraged his love of mathematics when he was in second grade, in 1976. In 1981 he won a scholarship to attend St Aloysius' College in Sydney, and was a vice-captain of the College and Captain of the Australian Schools Debating Team. He gra |
https://en.wikipedia.org/wiki/Joe%20job | A Joe job is a spamming technique that sends out unsolicited e-mails using spoofed sender data. Early Joe jobs aimed at tarnishing the reputation of the apparent sender or inducing the recipients to take action against them (see also email spoofing), but they are now typically used by commercial spammers to conceal the true origin of their messages and to trick recipients into opening emails apparently coming from a trusted source.
Origin and motivation
The name "Joe job" originated from such a spam attack on Joe Doll, webmaster of joes.com, in early 1997. One user's joes.com account was removed because of advertising through spam. In retaliation, the user sent new spam with headers forged to make it appear that Joe Doll was responsible. Besides prompting angry replies, it also caused joes.com to fall prey to denial-of-service attacks, from anti-spam vigilantes who thought he had sent the mail, which temporarily took the site down.
Some e-mail Joe jobs are acts of revenge like the original, whether by individuals or by organizations that also use spam for other purposes. Spammers use the technique to cycle through domains and to try to get around spam filters and blocks.
Joe-jobbers could also be businesses trying to defame a competitor or a spammer trying to harm the reputation of an anti-spam group or filtering service. Joe job attacks in other media are often motivated politically or through personal enmity.
Form
Joe jobs usually look like normal spam, although they might also disguise themselves as other types of scams or even as legitimate (but misdirected) messages.
Joe jobbing (or "joeing") can take different forms, but most incidents involve either e-mail or Usenet. They are sometimes seen on instant messaging systems as well. In general, joe jobbing is seen only on messaging systems with weak or no sender authentication, or where most users will assume the purported sender to be the actual one.
If the Joe-jobber is imitating a normal spam, it will sim |
https://en.wikipedia.org/wiki/Homogeneous%20function | In mathematics, a homogeneous function is a function of several variables such that, if all its arguments are multiplied by a scalar, then its value is multiplied by some power of this scalar, called the degree of homogeneity, or simply the degree; that is, if is an integer, a function of variables is homogeneous of degree if
for every and
For example, a homogeneous polynomial of degree defines a homogeneous function of degree .
The above definition extends to functions whose domain and codomain are vector spaces over a field : a function between two -vector spaces is homogeneous of degree if
for all nonzero and This definition is often further generalized to functions whose domain is not , but a cone in , that is, a subset of such that implies for every nonzero scalar .
In the case of functions of several real variables and real vector spaces, a slightly more general form of homogeneity called positive homogeneity is often considered, by requiring only that the above identities hold for and allowing any real number as a degree of homogeneity. Every homogeneous real function is positively homogeneous. The converse is not true, but is locally true in the sense that (for integer degrees) the two kinds of homogeneity cannot be distinguished by considering the behavior of a function near a given point.
A norm over a real vector space is an example of a positively homogeneous function that is not homogeneous. A special case is the absolute value of real numbers. The quotient of two homogeneous polynomials of the same degree gives an example of a homogeneous function of degree zero. This example is fundamental in the definition of projective schemes.
Definitions
The concept of a homogeneous function was originally introduced for functions of several real variables. With the definition of vector spaces at the end of 19th century, the concept has been naturally extended to functions between vector spaces, since a tuple of variable values can be co |
https://en.wikipedia.org/wiki/OpenSSI | OpenSSI is an open-source single-system image clustering system. It allows a collection of computers to be treated as one large system, allowing applications running on any one machine access to the resources of all the machines in the cluster.
OpenSSI is based on the Linux operating system and was released as an open source project by Compaq in 2001.
It is the final stage of a long process of development, stretching back to LOCUS, developed in the early 1980s.
Description
OpenSSI allows a cluster of individual computers (nodes) to be treated as one large system. Processes run on any node have full access to the resources of all nodes. Processes can be migrated from node to node automatically to balance system utilization. Inbound network connections can be directed to the least loaded node available.
OpenSSI is designed to be used for both high performance and high availability clusters. It is possible to create an OpenSSI cluster with no single point of failure, for example the file system can be mirrored between two nodes, so if one node crashes the process accessing the file will fail over to the other node. Alternatively the cluster can be designed in such a manner that every node has direct access to the file system.
Features
Single process space
OpenSSI provides a single process space – every process is visible from every node, and can be managed from any node using the normal Linux commands (ps, kill, renice and so on). The Linux /proc virtual filesystem shows all running processes on all nodes.
The implementation of the single process space is accomplished using the VPROC abstraction invented by Locus for the OSF/1 AD operating system.
Migration
OpenSSI allows migration of running processes between nodes. When running processes are migrated they continue to have access to any open files, IPC objects or network connections.
Processes can be manually migrated, either by the process calling the special OpenSSI migrate(2) system call, or by writin |
https://en.wikipedia.org/wiki/Single%20system%20image | In distributed computing, a single system image (SSI) cluster is a cluster of machines that appears to be one single system. The concept is often considered synonymous with that of a distributed operating system, but a single image may be presented for more limited purposes, just job scheduling for instance, which may be achieved by means of an additional layer of software over conventional operating system images running on each node. The interest in SSI clusters is based on the perception that they may be simpler to use and administer than more specialized clusters.
Different SSI systems may provide a more or less complete illusion of a single system.
Features of SSI clustering systems
Different SSI systems may, depending on their intended usage, provide some subset of these features.
Process migration
Many SSI systems provide process migration.
Processes may start on one node and be moved to another node, possibly for resource balancing or administrative reasons. As processes are moved from one node to another, other associated resources (for example IPC resources) may be moved with them.
Process checkpointing
Some SSI systems allow checkpointing of running processes, allowing their current state to be saved and reloaded at a later date.
Checkpointing can be seen as related to migration, as migrating a process from one node to another can be implemented by first checkpointing the process, then restarting it on another node. Alternatively checkpointing can be considered as migration to disk.
Single process space
Some SSI systems provide the illusion that all processes are running on the same machine - the process management tools (e.g. "ps", "kill" on Unix like systems) operate on all processes in the cluster.
Single root
Most SSI systems provide a single view of the file system. This may be achieved by a simple NFS server, shared disk devices or even file replication.
The advantage of a single root view is that processes may be run on any available nod |
https://en.wikipedia.org/wiki/Trusted%20operating%20system | Trusted Operating System (TOS) generally refers to an operating system that provides sufficient support for multilevel security and evidence of correctness to meet a particular set of government requirements.
The most common set of criteria for trusted operating system design is the Common Criteria combined with the Security Functional Requirements (SFRs) for Labeled Security Protection Profile (LSPP) and mandatory access control (MAC). The Common Criteria is the result of a multi-year effort by the governments of the U.S., Canada, United Kingdom, France, Germany, the Netherlands and other countries to develop a harmonized security criteria for IT products.
Examples
Examples of certified trusted operating systems are:
Apple Mac OS X 10.6 (Rated EAL 3+)
HP-UX 11i v3 (Rated EAL 4+)
Some Linux distributions (Rated up to EAL 4+)
Microsoft Windows 7 and Microsoft Server 2008 R2 (Rated EAL 4+)
AIX 5L with PitBull Foundation (Rated EAL 4+)
Trusted Solaris
Trusted UNICOS 8.0 (Rated B1)
XTS-400 (Rated EAL5+)
IBM VM (SP, BSE, HPO, XA, ESA, etc.) with RACF
Examples of operating systems that might be certifiable are:
FreeBSD with the TrustedBSD extensions
SELinux (see FAQ)
Companies that have created trusted operating systems include:
Addamax (BSD, SVR3, SVR4, HP/UX)
Argus Systems Group (Solaris, AIX, Linux)
AT&T (System V)
BAE Systems (XTS Unix)
Bull (AIX)
Data General (DG/UX)
Digital Equipment Corporation (Ultrix)
Forcepoint (Hardened SELinux)
Gemini Computers (GEMSOS)
General Dynamics C4 Systems (Linux)
Harris Corporation (SVR3, SVR4)
Hewlett-Packard (HP/UX)
Honeywell (Multics)
IBM (OS/390, AIX)
SCO (SCO Unix)
Secure Computing Corporation (LOCK, Mach, BSD)
SecureWare (Apple A/UX, HP/UX, SCO)
Sequent Computer Systems (Dynix/ptx)
Silicon Graphics (IRIX)
Sun Microsystems (SunOS, Solaris)
Trusted Information Systems (Xenix, Mach)
See also
Common Criteria
Comparison of operating systems
Security-evaluated operating system
Security-focused o |
https://en.wikipedia.org/wiki/Compile%20farm | A compile farm is a server farm, a collection of one or more servers, which has been set up to compile computer programs remotely for various reasons. Uses of a compile farm include:
Cross-platform development: When writing software that runs on multiple processor architectures and operating systems, it can be infeasible for each developer to have their own machine for each architecture — for example, one platform might have an expensive or obscure type of CPU. In this scenario, a compile farm is useful as a tool for developers to build and test their software on a shared server running the target operating system and CPU. Compile farms may be preferable to cross-compilation as cross compilers are often complicated to configure, and in some cases compilation is only possible on the target, making cross-compilation impossible.
Cross-platform continuous integration testing: in this scenario, each server has a different processor architecture or runs a different operating system; scripts automatically build the latest version of a source tree from a version control repository. One of the difficulties of cross-platform development is that a programmer may unintentionally introduce an error that causes the software to stop functioning on a different CPU/OS platform from the one they are using. By using a cross-platform compile farm, such errors can be identified and fixed.
Distributed compilation: Building software packages typically requires operations that can be run in parallel (for example, compiling individual source code files). By using a compile farm, these operations can be run in parallel on separate machines. An example of a program which can be used to do this is distcc.
One example of a compile farm was the service provided by SourceForge until 2006. The SourceForge compile farm was composed of twelve machines of various computer architectures running a variety of operating systems, and was intended to allow developers to test and use their progr |
https://en.wikipedia.org/wiki/Robotic%20mapping | Robotic mapping is a discipline related to computer vision and cartography. The goal for an autonomous robot is to be able to construct (or use) a map (outdoor use) or floor plan (indoor use) and to localize itself and its recharging bases or beacons in it. Robotic mapping is that branch which deals with the study and application of ability to localize itself in a map / plan and sometimes to
construct the map or floor plan by the autonomous robot.
Evolutionarily shaped blind action may suffice to keep some animals alive. For some insects for example, the environment is not interpreted as a map, and they survive only with a triggered response. A slightly more elaborated navigation strategy dramatically enhances the capabilities of the robot. Cognitive maps enable planning capacities and use of current perceptions, memorized events, and expected consequences.
Operation
The robot has two sources of information: the idiothetic and the allothetic sources. When in motion, a robot can use dead reckoning methods such as tracking the number of revolutions of its wheels; this corresponds to the idiothetic source and can give the absolute position of the robot, but it is subject to cumulative error which can grow quickly.
The allothetic source corresponds the sensors of the robot, like a camera, a microphone, laser, lidar or sonar. The problem here is "perceptual aliasing". This means that two different places can be perceived as the same. For example, in a building, it is nearly impossible to determine a location solely with the visual information, because all the corridors may look the same. 3-dimensional models of a robot's environment can be generated using range imaging sensors or 3D scanners.
Map representation
The internal representation of the map can be "metric" or "topological":
The metric framework is the most common for humans and considers a two-dimensional space in which it places the objects. The objects are placed with precise coordinates. This repre |
https://en.wikipedia.org/wiki/Science%20and%20Engineering%20Research%20Council | The Science and Engineering Research Council (SERC) and its predecessor the Science Research Council (SRC) were the UK agencies in charge of publicly funded scientific and engineering research activities, including astronomy, biotechnology and biological sciences, space research and particle physics, between 1965 and 1994.
History
The SERC also had oversight of:
the Royal Greenwich Observatory (RGO)
the Royal Observatory Edinburgh (ROE)
the Rutherford Appleton Laboratory (RAL)
the Daresbury Laboratory
From its formation in 1965 until 1981 it was known as the Science Research Council (SRC). The SRC had been formed in 1965 as a result of the Trend Committee enquiry into the organisation of civil science in the UK. Previously the Minister for Science had been responsible for various research activities in the Department of Scientific and Industrial Research (DSIR) and more loosely with a variety of agencies concerned with the formulation of civil scientific policy. One of the main problems addressed by the enquiry was how to decide the priorities for government funding across all areas of scientific research. Previously this task had been the responsibility of the Treasury without direct scientific advice. The other Research Councils formed in 1965 were:
the Natural Environment Research Council (NERC)
the Social Science Research Council (SSRC)
the Agricultural Research Council (ARC)
These bodies joined the Medical Research Council (MRC) which had existed since 1920. In 1981, to reflect the increased emphasis on engineering research, the SRC was renamed the Science and Engineering Research Council. In 1994, the new Director General of Research Councils was charged with reorganization of the four existing research councils, and this resulted in the SERC being split three bodies:
the Particle Physics and Astronomy Research Council (PPARC)
the Engineering and Physical Sciences Research Council (EPSRC)
the Biotechnology and Biological Sciences Research Cou |
https://en.wikipedia.org/wiki/HOOD%20method | HOOD (Hierarchic Object-Oriented Design) is a detailed software design method. It is based on hierarchical decomposition of a software problem. It comprises textual and graphical representations of the design.
HOOD was initially created for the European Space Agency and is used in such varied domains as aerospace (Eurofighter Typhoon, Helios 2 Earth Observation ground control, Ariane 5 on-board computer), ground transportation, and nuclear plants.
HOOD main target languages are Ada, Fortran and C.
External links
Introduction to HOOD HOOD page at ESA
ESA's HOOD user manual, gzipped postscript
Software design
Data modeling languages
Specification languages |
https://en.wikipedia.org/wiki/Haldane%27s%20rule | Haldane's rule is an observation about the early stage of speciation, formulated in 1922 by the British evolutionary biologist J. B. S. Haldane, that states that if — in a species hybrid — only one sex is inviable or sterile, that sex is more likely to be the heterogametic sex. The heterogametic sex is the one with two different sex chromosomes; in therian mammals, for example, this is the male.
Overview
Haldane himself described the rule as:
Haldane's rule applies to the vast majority of heterogametic organisms. This includes the case where two species make secondary contact in an area of sympatry and form hybrids after allopatric speciation has occurred.
The rule includes both male heterogametic (XY or XO-type sex determination, such as found in mammals and Drosophila fruit flies) and female heterogametic (ZW or Z0-type sex determination, as found in birds and butterflies), and some dioecious plants such as campions.
Hybrid dysfunction (sterility and inviability) is a major form of post-zygotic reproductive isolation, which occurs in early stages of speciation. Evolution can produce a similar pattern of isolation in a vast array of different organisms. However, the actual mechanisms leading to Haldane's rule in different taxa remain largely undefined.
Hypotheses
Many different hypotheses have been advanced to address the evolutionary mechanisms to produce Haldane's rule. Currently, the most popular explanation for Haldane's rule is the composite hypothesis, which divides Haldane's rule into multiple subdivisions, including sterility, inviability, male heterogamety, and female heterogamety. The composite hypothesis states that Haldane's rule in different subdivisions has different causes. Individual genetic mechanisms may not be mutually exclusive, and these mechanisms may act together to cause Haldane's rule in any given subdivision. In contrast to these views that emphasize genetic mechanisms, another view hypothesizes that population dynamics during populat |
https://en.wikipedia.org/wiki/Blastomere | In biology, a blastomere is a type of cell produced by cell division (cleavage) of the zygote after fertilization; blastomeres are an essential part of blastula formation, and blastocyst formation in mammals.
Human blastomere characteristics
In humans, blastomere formation begins immediately following fertilization and continues through the first week of embryonic development. About 90 minutes after fertilization, the zygote divides into two cells. The two-cell blastomere state, present after the zygote first divides, is considered the earliest mitotic product of the fertilized oocyte. These mitotic divisions continue and result in a grouping of cells called blastomeres. During this process, the total size of the embryo does not increase, so each division results in smaller and smaller cells. When the zygote contains 16 to 32 blastomeres it is referred to as a morula. These are the preliminary stages in the embryo beginning to form. Once this begins, microtubules within the morula's cytosolic material in the blastomere cells can develop into important membrane functions, such as sodium pumps. These pumps allow the inside of the embryo to fill with blastocoelic fluid, which supports the further growth of life.
The blastomere is considered totipotent; that is, blastomeres are capable of developing from a single cell into a fully fertile adult organism. This has been demonstrated through studies and conjectures made with mouse blastomeres, which have been accepted as true for most mammalian blastomeres as well. Studies have analyzed monozygotic twin mouse blastomeres in their two-cell state, and have found that when one of the twin blastomeres is destroyed, a fully fertile adult mouse can still develop. Thus, it can be assumed that since one of the twin cells was totipotent, the destroyed one originally was as well.
Relative blastomere size within the embryo is dependent not only on the stage of the cleavage, but also on the regularity of the cleavage amongst t |
https://en.wikipedia.org/wiki/Induction%20heating | Induction heating is the process of heating electrically conductive materials, namely metals or semi-conductors, by electromagnetic induction, through heat transfer passing through an inductor that creates an electromagnetic field within the coil to heat up and possibly melt steel, copper, brass, graphite, gold, silver, aluminum, or carbide.
An important feature of the induction heating process is that the heat is generated inside the object itself, instead of by an external heat source via heat conduction. Thus objects can be heated very rapidly. In addition, there need not be any external contact, which can be important where contamination is an issue. Induction heating is used in many industrial processes, such as heat treatment in metallurgy, Czochralski crystal growth and zone refining used in the semiconductor industry, and to melt refractory metals that require very high temperatures. It is also used in induction cooktops.
An induction heater consists of an electromagnet and an electronic oscillator that passes a high-frequency alternating current (AC) through the electromagnet. The rapidly alternating magnetic field penetrates the object, generating electric currents inside the conductor called eddy currents. The eddy currents flow through the resistance of the material, and heat it by Joule heating. In ferromagnetic and ferrimagnetic materials, such as iron, heat also is generated by magnetic hysteresis losses. The frequency of the electric current used for induction heating depends on the object size, material type, coupling (between the work coil and the object to be heated), and the penetration depth.
Applications
Induction heating allows the targeted heating of an applicable item for applications including surface hardening, melting, brazing and soldering, and heating to fit. Due to their ferromagnetic nature, iron and its alloys respond best to induction heating. Eddy currents can, however, be generated in any conductor, and magnetic hysteresis ca |
https://en.wikipedia.org/wiki/Voltage%20regulator | A voltage regulator is a system designed to automatically maintain a constant voltage. It may use a simple feed-forward design or may include negative feedback. It may use an electromechanical mechanism, or electronic components. Depending on the design, it may be used to regulate one or more AC or DC voltages.
Electronic voltage regulators are found in devices such as computer power supplies where they stabilize the DC voltages used by the processor and other elements. In automobile alternators and central power station generator plants, voltage regulators control the output of the plant. In an electric power distribution system, voltage regulators may be installed at a substation or along distribution lines so that all customers receive steady voltage independent of how much power is drawn from the line.
Electronic voltage regulators
A simple voltage/current regulator can be made from a resistor in series with a diode (or series of diodes). Due to the logarithmic shape of diode V-I curves, the voltage across the diode changes only slightly due to changes in current drawn or changes in the input. When precise voltage control and efficiency are not important, this design may be fine. Since the forward voltage of a diode is small, this kind of voltage regulator is only suitable for
low voltage regulated output. When higher voltage output is needed, a zener diode or series of zener diodes may be employed. Zener diode regulators make use of the zener diode's fixed reverse voltage, which can be quite large.
Feedback voltage regulators operate by comparing the actual output voltage to some fixed reference voltage. Any difference is amplified and used to control the regulation element in such a way as to reduce the voltage error. This forms a negative feedback control loop; increasing the open-loop gain tends to increase regulation accuracy but reduce stability. (Stability is avoidance of oscillation, or ringing, during step changes.) There will also be a trade-off |
https://en.wikipedia.org/wiki/Bertrand%20paradox%20%28probability%29 | The Bertrand paradox is a problem within the classical interpretation of probability theory. Joseph Bertrand introduced it in his work Calcul des probabilités (1889), as an example to show that the principle of indifference may not produce definite, well-defined results for probabilities if it is applied uncritically when the domain of possibilities is infinite.
Bertrand's formulation of the problem
The Bertrand paradox is generally presented as follows: Consider an equilateral triangle inscribed in a circle. Suppose a chord of the circle is chosen at random. What is the probability that the chord is longer than a side of the triangle?
Bertrand gave three arguments (each using the principle of indifference), all apparently valid, yet yielding different results:
The "random endpoints" method: Choose two random points on the circumference of the circle and draw the chord joining them. To calculate the probability in question imagine the triangle rotated so its vertex coincides with one of the chord endpoints. Observe that if the other chord endpoint lies on the arc between the endpoints of the triangle side opposite the first point, the chord is longer than a side of the triangle. The length of the arc is one third of the circumference of the circle, therefore the probability that a random chord is longer than a side of the inscribed triangle is .
The "random radial point" method: Choose a radius of the circle, choose a point on the radius and construct the chord through this point and perpendicular to the radius. To calculate the probability in question imagine the triangle rotated so a side is perpendicular to the radius. The chord is longer than a side of the triangle if the chosen point is nearer the center of the circle than the point where the side of the triangle intersects the radius. The side of the triangle bisects the radius, therefore the probability a random chord is longer than a side of the inscribed triangle is .
The "random midpoint" method: |
https://en.wikipedia.org/wiki/Mating%20system | A mating system is a way in which a group is structured in relation to sexual behaviour. The precise meaning depends upon the context. With respect to animals, the term describes which males and females mate under which circumstances. Recognised systems include monogamy, polygamy (which includes polygyny, polyandry, and polygynandry), and promiscuity, all of which lead to different mate choice outcomes and thus these systems affect how sexual selection works in the species which practice them. In plants, the term refers to the degree and circumstances of outcrossing. In human sociobiology, the terms have been extended to encompass the formation of relationships such as marriage.
In plants
The primary mating systems in plants are outcrossing (cross-fertilisation), autogamy (self-fertilisation) and apomixis (asexual reproduction without fertilization, but only when arising by modification of sexual function). Mixed mating systems, in which plants use two or even all three mating systems, are not uncommon.
A number of models have been used to describe the parameters of plant mating systems. The basic model is the mixed mating model, which is based on the assumption that every fertilisation is either self-fertilisation or completely random cross-fertilisation. More complex models relax this assumption; for example, the effective selfing model recognises that mating may be more common between pairs of closely related plants than between pairs of distantly related plants.
In animals
The following are some of the mating systems generally recognized in animals:
Monogamy: One male and one female have an exclusive mating relationship. The term "pair bonding" often implies this. This is associated with one-male, one-female group compositions. There are two types of monogamy: type 1, which is facultative, and type 2, which is obligate. Facultative monogamy occurs when there are very low densities in a species. This means that mating occurs with only a single member of the |
https://en.wikipedia.org/wiki/Autophagy | Autophagy (or autophagocytosis; from the Ancient Greek , , meaning "self-devouring" and , , meaning "hollow") is the natural, conserved degradation of the cell that removes unnecessary or dysfunctional components through a lysosome-dependent regulated mechanism. It allows the orderly degradation and recycling of cellular components. Although initially characterized as a primordial degradation pathway induced to protect against starvation, it has become increasingly clear that autophagy also plays a major role in the homeostasis of non-starved cells. Defects in autophagy have been linked to various human diseases, including neurodegeneration and cancer, and interest in modulating autophagy as a potential treatment for these diseases has grown rapidly.
Four forms of autophagy have been identified: macroautophagy, microautophagy, chaperone-mediated autophagy (CMA), and crinophagy. In macroautophagy (the most thoroughly researched form of autophagy), cytoplasmic components (like mitochondria) are targeted and isolated from the rest of the cell within a double-membrane vesicle known as an autophagosome, which, in time, fuses with an available lysosome, bringing its specialty process of waste management and disposal; and eventually the contents of the vesicle (now called an autolysosome) are degraded and recycled. In crinophagy (the least well-known and researched form of autophagy), unnecessary secretory granules are degraded and recycled.
In disease, autophagy has been seen as an adaptive response to stress, promoting survival of the cell; but in other cases, it appears to promote cell death and morbidity. In the extreme case of starvation, the breakdown of cellular components promotes cellular survival by maintaining cellular energy levels.
The word "autophagy" was in existence and frequently used from the middle of the 19th century. In its present usage, the term autophagy was coined by Belgian biochemist Christian de Duve in 1963 based on his discovery of the func |
https://en.wikipedia.org/wiki/List%20of%20partition%20topics | Generally, a partition is a division of a whole into non-overlapping parts. Among the kinds of partitions considered in mathematics are
partition of a set or an ordered partition of a set,
partition of a graph,
partition of an integer,
partition of an interval,
partition of unity,
partition of a matrix; see block matrix, and
partition of the sum of squares in statistics problems, especially in the analysis of variance,
quotition and partition, two ways of viewing the operation of division of integers.
Integer partitions
Composition (number theory)
Ewens's sampling formula
Ferrers graph
Glaisher's theorem
Landau's function
Partition function (number theory)
Pentagonal number theorem
Plane partition
Quotition and partition
Rank of a partition
Crank of a partition
Solid partition
Young tableau
Young's lattice
Set partitions
Bell number
Bell polynomials
Dobinski's formula
Cumulant
Data clustering
Equivalence relation
Exact cover
Knuth's Algorithm X
Dancing Links
Exponential formula
Faà di Bruno's formula
Feshbach–Fano partitioning
Foliation
Frequency partition
Graph partition
Kernel of a function
Lamination (topology)
Matroid partitioning
Multipartition
Multiplicative partition
Noncrossing partition
Ordered partition of a set
Partition calculus
Partition function (quantum field theory)
Partition function (statistical mechanics)
Derivation of the partition function
Partition of an interval
Partition of a set
Ordered partition
Partition refinement
Disjoint-set data structure
Partition problem
3-partition problem
Partition topology
Quotition and partition
Recursive partitioning
Stirling number
Stirling transform
Stratification (mathematics)
Tverberg partition
Twelvefold way
In probability and stochastic processes
Chinese restaurant process
Dobinski's formula
Ewens's sampling formula
Law of tota |
https://en.wikipedia.org/wiki/Persistence%20of%20a%20number | In mathematics, the persistence of a number is the number of times one must apply a given operation to an integer before reaching a fixed point at which the operation no longer alters the number.
Usually, this involves additive or multiplicative persistence of a non-negative integer, which is how often one has to replace the number by the sum or product of its digits until one reaches a single digit. Because the numbers are broken down into their digits, the additive or multiplicative persistence depends on the radix. In the remainder of this article, base ten is assumed.
The single-digit final state reached in the process of calculating an integer's additive persistence is its digital root. Put another way, a number's additive persistence counts how many times we must sum its digits to arrive at its digital root.
Examples
The additive persistence of 2718 is 2: first we find that 2 + 7 + 1 + 8 = 18, and then that 1 + 8 = 9. The multiplicative persistence of 39 is 3, because it takes three steps to reduce 39 to a single digit: 39 → 27 → 14 → 4. Also, 39 is the smallest number of multiplicative persistence 3.
Smallest numbers of a given multiplicative persistence
In base 10, there is thought to be no number with a multiplicative persistence > 11: this is known to be true for numbers up to 1020,000. The smallest numbers with persistence 0, 1, 2, ... are:
0, 10, 25, 39, 77, 679, 6788, 68889, 2677889, 26888999, 3778888999, 277777788888899.
The search for these numbers can be sped up by using additional properties of the decimal digits of these record-breaking numbers. These digits must be in increasing order (with the exception of the second number, 10), and – except for the first two digits – all digits must be 7, 8, or 9. There are also additional restrictions on the first two digits.
Based on these restrictions, the number of candidates for n-digit numbers with record-breaking persistence is only proportional to the square of n, a tiny fraction of all possible |
https://en.wikipedia.org/wiki/Straight-twelve%20engine | A straight-12 engine or inline-12 engine is a twelve-cylinder piston engine with all twelve cylinders mounted in a straight line along the crankcase.
Land use
Due to the very long length of a straight-twelve engine, they are rarely used in automobiles. The first known example is a engine in the 1920 French Corona car; however it is not known if any were cars sold. Packard also experimented with an automobile powered by an inline 12 in 1929.
The straight-12 has also been used for large military trucks.
Marine use
Some Russian firms built straight-12s for use in ships in the 1960s and 1970s.
MAN Diesel & Turbo 12K98ME and 12S90ME-C and the Wärtsilä-Sulzer RTA96-C are examples of contemporary marine engines in L-12-cylinder configuration. These are popular for propulsion in container ships.
References
Piston engine configurations
12-cylinder engines
12 |
https://en.wikipedia.org/wiki/Modular%20building | A modular building is a prefabricated building that consists of repeated sections called modules. Modularity involves constructing sections away from the building site, then delivering them to the intended site. Installation of the prefabricated sections is completed on site. Prefabricated sections are sometimes placed using a crane. The modules can be placed side-by-side, end-to-end, or stacked, allowing for a variety of configurations and styles. After placement, the modules are joined together using inter-module connections, also known as inter-connections. The inter-connections tie the individual modules together to form the overall building structure.
Uses
Modular buildings may be used for long-term, temporary or permanent facilities, such as construction camps, schools and classrooms, civilian and military housing, and industrial facilities. Modular buildings are used in remote and rural areas where conventional construction may not be reasonable or possible, for example, the Halley VI accommodation pods used for a BAS Antarctic expedition. Other uses have included churches, health care facilities, sales and retail offices, fast food restaurants and cruise ship construction. They can also be used in areas that have weather concerns, such as hurricanes. Modular buildings are often used to provide temporary facilities, including toilets and ablutions at events. The portability of the buildings makes them popular with hire companies and clients alike. The use of modular buildings enables events to be held at locations where existing facilities are unavailable, or unable to support the number of event attendees.
Construction process
Construction is offsite, using lean manufacturing techniques to prefabricate single or multi-story buildings in deliverable module sections. Often, modules are based around standard 20 foot containers, using the same dimensions, structures, building and stacking/placing techniques, but with smooth (instead of corrugated) walls, glo |
https://en.wikipedia.org/wiki/Cipher%20Bureau%20%28Poland%29 | The Cipher Bureau (Polish: Biuro Szyfrów, ) was the interwar Polish General Staff's Second Department's unit charged with SIGINT and both cryptography (the use of ciphers and codes) and cryptanalysis (the study of ciphers and codes, for the purpose of "breaking" them).
The precursor of the agency that would become the Cipher Bureau was created in May 1919, during the Polish-Soviet War (1919–1921), and played a vital role in securing Poland's survival and victory in that war.
In mid-1931, the Cipher Bureau was formed by the merger of pre-existing agencies. In December 1932, the Bureau began breaking Germany's Enigma ciphers. Over the next seven years, Polish cryptologists overcame the growing structural and operating complexities of the plugboard-equipped Enigma. The Bureau also broke Soviet cryptography.
Five weeks before the outbreak of World War II, on 25 July 1939, in Warsaw, the Polish Cipher Bureau revealed its Enigma-decryption techniques and equipment to representatives of French and British military intelligence, which had been unable to make any headway against Enigma. This Polish intelligence-and-technology transfer would give the Allies an unprecedented advantage (Ultra) in their ultimately victorious prosecution of World War II.
Background
On 8 May 1919 Lt. Józef Serafin Stanslicki established a Polish Army "Cipher Section" (), precursor to the "Cipher Bureau" (). The Cipher Section reported to the Polish General Staff and contributed substantially to Poland's defense by Józef Piłsudski's forces during the Polish-Soviet War of 1919–1921, thereby helping preserve Poland's independence, recently regained in the wake of World War I. The Cipher Section's purview included both ciphers and codes. In Polish the term "cipher" () loosely refers to both these two principal categories of cryptography. (Compare the opposite practice in English, which loosely refers to both codes and ciphers as "codes".)
During the Polish–Soviet War (1919–1921), approximately a |
https://en.wikipedia.org/wiki/Paper%20football | Paper football (also called FIKI football, finger football, flick football, or tabletop football) refers to a table-top game, loosely based on American football, in which a sheet of paper folded into a small triangle is slid back and forth across a table top by two opponents. This game is widely practiced for entertainment, mostly by students in primary, middle school, and high school age in the United States. Though its origin is in dispute, it was widely played at churches in Madison, Wisconsin in the early 1970’s. The youth group at Grace Baptist Church held weekly events and competitions including monthly championships.
Gameplay
The game uses a piece of paper folded into a triangle, called the 'ball'. The starting player begins by kicking off the ball. To perform a kickoff, the ball is placed on the table, suspended by one of the player's hands with the index finger on the upper tip of the ball, then the player flicks the ball with the other hand's thumb and index finger. If the ball ends up flying off the table or hanging on the edge of the table, the kickoff is redone. If the ball lands on the table without reaching the edge of the receiving player's side, players take turns pushing it with a steady fast motion towards the opponent's side.
The player scores points by getting the ball hanging on the edge of the opponent's side, called a touchdown. Every time a touchdown is scored, the player who scored has a chance to make a field goal, which has that player flick the ball as in the kickoff through the opponent's goal post, formed by placing both wrists parallel to the table on the edge, with the tips of both thumbs touching each other and both index fingers pointing straight upward. If the field goal is successful, the kicking player scores one point. The player who conceded points starts the next kickoff.
The game ends based on the agreed-upon rules, be it time limit (the player with the most points when the predetermined amount of time has elapsed wins) |
https://en.wikipedia.org/wiki/JavaOS | JavaOS is a discontinued operating system based on a Java virtual machine. It was originally developed by Sun Microsystems. Unlike Windows, macOS, Unix, or Unix-like systems which are primarily written in the C programming language, JavaOS is primarily written in Java. It is now considered a legacy system.
History
The Java programming language was introduced by Sun in May 1995. Jim Mitchell and Peter Madany at JavaSoft designed a new operating system, codenamed Kona, written completely in Java. In March 1996, Tom Saulpaugh joined the now seven-person Kona team to design an input/output (I/O) architecture, having come from Apple as Macintosh system software engineer since June 1985 and co-architect of Copland.
JavaOS was first evangelized in a Byte article. In 1996, JavaSoft's official product announcement described the compact OS designed to run "in anything from net computers to pagers". In early 1997, JavaSoft transferred JavaOS to SunSoft. In late 1997, Bob Rodriguez led the team to collaborate with IBM who then marketed the platform, accelerated development, and made significant key architectural contributions to the next release of JavaOS, eventually renamed JavaOS for Business. IBM indicated its focus was more on network computer thin clients, specifically to replace traditional IBM 3270 "green screen" and Unix X terminals, and to implement single application clients.
The Chorus distributed real-time operating system was used for its microkernel technology. This began with Chorus Systèmes SA, a French company, licensing JavaOS from Sun and replacing the earlier JavaOS hardware abstraction layer with the Chorus microkernel, thereby creating the Chorus/Jazz product, which was intended to allow Java applications to run in a distributed, real-time embedded system environment. Then in September 1997, it was announced that Sun Microsystems was acquiring Chorus Systèmes SA.
In 1999, Sun and IBM announced the discontinuation of the JavaOS product. As early as 20 |
https://en.wikipedia.org/wiki/Lites | Lites is a discontinued Unix-like operating system, based on 4.4BSD and the Mach microkernel. Specifically, Lites is a multi-threaded server and emulation library that provided unix functions to a Mach-based system. At the time of its release, Lites provided binary compatibility with 4.4BSD, NetBSD, FreeBSD, 386BSD, UX (4.3BSD), and Linux.
Lites was originally written by Johannes Helander at Helsinki University of Technology, and was further developed by the Flux Research Group at the University of Utah.
See also
HPBSD
References
External links
, Utah Lites
Berkeley Software Distribution
Mach (kernel)
Microkernel-based operating systems
Microkernels |
https://en.wikipedia.org/wiki/DOS/360%20and%20successors | Disk Operating System/360, also DOS/360, or simply DOS, is the discontinued first member of a sequence of operating systems for IBM System/360, System/370 and later mainframes. It was announced by IBM on the last day of 1964, and it was first delivered in June 1966. In its time, DOS/360 was the most widely used operating system in the world.
DOS versions
BOS/360
The Basic Operating System(BOS) was an early version of DOS and TOS which could provide usable functionality on a system with as little as 8 KB of main storage and one 2311 disk drive.
TOS/360
TOS/360 (Tape Operating System/360, not a DOS as such and not so called) was an IBM operating system for the System/360, used in the early days around 1965 to support the System/360 Model 30 and similar platforms.
TOS, as per the "Tape" in the name, required a tape drive. It shared most of the code base and some manuals with IBM's DOS/360.
TOS went through 14 releases, and was discontinued when disks such as the IBM 2311 and IBM 2314 became more affordable at the time of System/360, whereas they had been an expensive luxury on the IBM 7090.
DOS/360
DOS/360 was the primary operating system for most small to midsize S/360 installations.
DOS/VS
DOS/VS was released in 1972. The first DOS/VS release was numbered "Release 28" to signify an incremental upgrade from DOS/360. It added virtual memory in support of the new System/370 series hardware. It used a fixed page table which mapped a single address space of up to 16 megabytes for all partitions combined.
DOS/VS increased the number of partitions (separate simultaneous programs) from three (named Background, Foreground 1 and Foreground 2) to five (BG and F1 through F4) and allowed a system wide total of fifteen subtasks.
DOS/VS was succeeded by DOS/VSE through z/VSE.
DOS/VSE
DOS/VSE was introduced in 1979 as an "extended" version of DOS/VS to support the new 4300 processors.
The 4300 systems included a feature called ECPS:VSE that provided a single-level st |
https://en.wikipedia.org/wiki/Extensible%20Application%20Markup%20Language | Extensible Application Markup Language (XAML ) is a declarative XML-based language developed by Microsoft for initializing structured values and objects. It is available under Microsoft's Open Specification Promise.
XAML is used extensively in Windows Presentation Foundation (WPF), Silverlight, Workflow Foundation (WF), Windows UI Library (WinUI), Universal Windows Platform (UWP), and .NET Multi-platform App UI (.NET MAUI). In WPF and UWP, XAML is a user interface markup language to define UI elements, data binding, and events. In WF, however, XAML defines workflows.
XAML elements map directly to Common Language Runtime (CLR) object instances, while XAML attributes map to CLR properties and events on those objects.
Anything that is created or implemented in XAML can be expressed using a more traditional .NET language, such as C# or Visual Basic .NET. However, a key aspect of the technology is the reduced complexity needed for tools to process XAML, because it is based on XML.
Technology
XAML originally stood for Extensible Avalon Markup Language, Avalon being the code-name for Windows Presentation Foundation (WPF). Before the end .NET Framework 3.0 development, however, Microsoft adopted XAML for Workflow Foundation (WF).
In WPF, XAML describes visual user interfaces. WPF allows for the definition of both 2D and 3D objects, rotations, animations, and a variety of other effects and features. A XAML file can be compiled into a Binary Application Markup Language (BAML) file, which may be inserted as a resource into a .NET Framework assembly. At run-time, the framework engine extracts the BAML file from assembly resources, parses it, and creates a corresponding WPF visual tree or workflow.
In WF contexts, XAML describes potentially long-running declarative logic, such as those created by process modeling tools and rules systems. The serialization format for workflows was previously called XOML, to differentiate it from UI markup use of XAML, but now they are no |
https://en.wikipedia.org/wiki/TV%20tuner%20card | A TV tuner card is a kind of television tuner that allows television signals to be received by a computer. Most TV tuners also function as video capture cards, allowing them to record television programs onto a hard disk much like the digital video recorder (DVR) does.
The interfaces for TV tuner cards are most commonly either PCI bus expansion card or the newer PCI Express (PCIe) bus for many modern cards, but PCMCIA, ExpressCard, or USB devices also exist. In addition, some video cards double as TV tuners, notably the ATI All-In-Wonder series. The card contains a tuner and an analog-to-digital converter (collectively known as the analog front end) along with demodulation and interface logic. Some lower-end cards lack an onboard processor and, like a Winmodem, rely on the system's CPU for demodulation.
Types
There are many types of tuner cards.
Analog tuners
Analog television cards output a raw video stream, suitable for real-time viewing but ideally requiring some sort of video compression if it is to be recorded.
Some cards also have analog input (composite video or S-Video) and many also provide a radio tuner.
An early example was the Aapps Corp. MicroTV for Apple Macintosh II, which debuted in 1989.
More-advanced TV tuners encode the signal to Motion JPEG or MPEG, relieving the main CPU of this load.
Hybrid tuners
A hybrid tuner has one tuner that can be configured to act as an analog tuner or a digital tuner. Switching between the systems is fairly easy, but cannot be done immediately. The card operates as a digital tuner or an analog tuner until reconfigured.
Combo tuners
This is similar to a hybrid tuner, except there are two separate tuners on the card. One can watch analog while recording digital, or vice versa. The card operates as an analog tuner and a digital tuner simultaneously. The advantages over two separate cards are cost and utilization of expansion slots in the computer. As many regions around the world convert from analog to digital |
https://en.wikipedia.org/wiki/Webcast | A webcast is a media presentation distributed over the Internet using streaming media technology to distribute a single content source to many simultaneous listeners/viewers. A webcast may either be distributed live or on demand. Essentially, webcasting is "broadcasting" over the Internet.
The largest "webcasters" include existing radio and TV stations, who "simulcast" their output through online TV or online radio streaming, as well as a multitude of Internet-only "stations". Webcasting usually consists of providing non-interactive linear streams or events. Rights and licensing bodies offer specific "webcasting licenses" to those wishing to carry out Internet broadcasting using copyrighted material.
Overview
Webcasting is used extensively in the commercial sector for investor relations presentations (such as annual general meetings), in e-learning (to transmit seminars), and for related communications activities. However, webcasting does not bear much, if any, relationship to web conferencing, which is designed for many-to-many interaction.
The ability to webcast using cheap/accessible technology has allowed independent media to flourish. There are many notable independent shows that broadcast regularly online. Often produced by average citizens in their homes they cover many interests and topics. Webcasts relating to computers, technology, and news are particularly popular and many new shows are added regularly.
Webcasting differs from podcasting in that webcasting refers to live streaming while podcasting simply refers to media files placed on the Internet.
The term "webcast" had previously been used to describe the distribution of Web or Internet content using conventional broadcast technologies such as those intended for digital video (Digital Video Broadcasting) and audio (Digital Audio Broadcasting), and in some cases even leveraging analogue broadcasting techniques traditionally used by Teletext services to deliver a limited "Best of the Web" selection |
https://en.wikipedia.org/wiki/Electronic%20signature | An electronic signature, or e-signature, is data that is logically associated with other data and which is used by the signatory to sign the associated data. This type of signature has the same legal standing as a handwritten signature as long as it adheres to the requirements of the specific regulation under which it was created (e.g., eIDAS in the European Union, NIST-DSS in the USA or ZertES in Switzerland).
Electronic signatures are a legal concept distinct from digital signatures, a cryptographic mechanism often used to implement electronic signatures. While an electronic signature can be as simple as a name entered in an electronic document, digital signatures are increasingly used in e-commerce and in regulatory filings to implement electronic signatures in a cryptographically protected way. Standardization agencies like NIST or ETSI provide standards for their implementation (e.g., NIST-DSS, XAdES or PAdES). The concept itself is not new, with common law jurisdictions having recognized telegraph signatures as far back as the mid-19th century and faxed signatures since the 1980s.
Description
An electronic signature is intended to provide a secure and accurate identification method for the signatory during a transaction.
Definitions of electronic signatures vary depending on the applicable jurisdiction. A common denominator in most countries is the level of an advanced electronic signature requiring that:
The signatory can be uniquely identified and linked to the signature
The signatory must have sole control of the private key that was used to create the electronic signature
The signature must be capable of identifying if its accompanying data has been tampered with after the message was signed
In the event that the accompanying data has been changed, the signature must be invalidated
Electronic signatures may be created with increasing levels of security, with each having its own set of requirements and means of creation on various levels that prove t |
https://en.wikipedia.org/wiki/John%20Maynard%20Smith%20Prize | The John Maynard Smith Prize is a prize given by the European Society for Evolutionary Biology on odd years to an outstanding young researcher. It was first awarded in 1997 and is named after the evolutionary biologist John Maynard Smith (1920–2004).
List of winners
Source: European Society for Evolutionary Biology
See also
List of biology awards
References
Biology awards
Awards established in 1997
European science and technology awards |
https://en.wikipedia.org/wiki/Littlewood%20conjecture | In mathematics, the Littlewood conjecture is an open problem () in Diophantine approximation, proposed by John Edensor Littlewood around 1930. It states that for any two real numbers α and β,
where is the distance to the nearest integer.
Formulation and explanation
This means the following: take a point (α, β) in the plane, and then consider the sequence of points
(2α, 2β), (3α, 3β), ... .
For each of these, multiply the distance to the closest line with integer x-coordinate by the distance to the closest line with integer y-coordinate. This product will certainly be at most 1/4. The conjecture makes no statement about whether this sequence of values will converge; it typically does not, in fact. The conjecture states something about the limit inferior, and says that there is a subsequence for which the distances decay faster than the reciprocal, i.e.
o(1/n)
in the little-o notation.
Connection to further conjectures
It is known that this would follow from a result in the geometry of numbers, about the minimum on a non-zero lattice point of a product of three linear forms in three real variables: the implication was shown in 1955 by Cassels and Swinnerton-Dyer. This can be formulated another way, in group-theoretic terms. There is now another conjecture, expected to hold for n ≥ 3: it is stated in terms of G = SLn(R), Γ = SLn(Z), and the subgroup D of diagonal matrices in G.
Conjecture: for any g in G/Γ such that Dg is relatively compact (in G/Γ), then Dg is closed.
This in turn is a special case of a general conjecture of Margulis on Lie groups.
Partial results
Borel showed in 1909 that the exceptional set of real pairs (α,β) violating the statement of the conjecture is of Lebesgue measure zero. Manfred Einsiedler, Anatole Katok and Elon Lindenstrauss have shown that it must have Hausdorff dimension zero; and in fact is a union of countably many compact sets of box-counting dimension zero. The result was proved by using a measure classification theorem |
https://en.wikipedia.org/wiki/Double%20Mersenne%20number | In mathematics, a double Mersenne number is a Mersenne number of the form
where p is prime.
Examples
The first four terms of the sequence of double Mersenne numbers are :
Double Mersenne primes
A double Mersenne number that is prime is called a double Mersenne prime. Since a Mersenne number Mp can be prime only if p is prime, (see Mersenne prime for a proof), a double Mersenne number can be prime only if Mp is itself a Mersenne prime. For the first values of p for which Mp is prime, is known to be prime for p = 2, 3, 5, 7 while explicit factors of have been found for p = 13, 17, 19, and 31.
Thus, the smallest candidate for the next double Mersenne prime is , or 22305843009213693951 − 1.
Being approximately 1.695,
this number is far too large for any currently known primality test. It has no prime factor below 1 × 1036.
There are probably no other double Mersenne primes than the four known.
Smallest prime factor of (where p is the nth prime) are
7, 127, 2147483647, 170141183460469231731687303715884105727, 47, 338193759479, 231733529, 62914441, 2351, 1399, 295257526626031, 18287, 106937, 863, 4703, 138863, 22590223644617, ... (next term is > 1 × 1036)
Catalan–Mersenne number conjecture
The recursively defined sequence
is called the sequence of Catalan–Mersenne numbers. The first terms of the sequence are:
Catalan discovered this sequence after the discovery of the primality of by Lucas in 1876. Catalan conjectured that they are prime "up to a certain limit". Although the first five terms are prime, no known methods can prove that any further terms are prime (in any reasonable time) simply because they are too huge. However, if is not prime, there is a chance to discover this by computing modulo some small prime (using recursive modular exponentiation). If the resulting residue is zero, represents a factor of and thus would disprove its primality. Since is a Mersenne number, such a prime factor would have to be of the form . Additionally, |
https://en.wikipedia.org/wiki/International%20Congress%20of%20Mathematicians | The International Congress of Mathematicians (ICM) is the largest conference for the topic of mathematics. It meets once every four years, hosted by the International Mathematical Union (IMU).
The Fields Medals, the IMU Abacus Medal (known before 2022 as the Nevanlinna Prize), the Gauss Prize, and the Chern Medal are awarded during the congress's opening ceremony. Each congress is memorialized by a printed set of Proceedings recording academic papers based on invited talks intended to be relevant to current topics of general interest. Being invited to talk at the ICM has been called "the equivalent ... of an induction to a hall of fame".
History
German mathematicians Felix Klein and Georg Cantor are credited with putting forward the idea of an international congress of mathematicians in the 1890s.
The University of Chicago, which had opened in 1892, organized an International Mathematical Congress at the Chicago World's Fair in 1893, where Felix Klein participated as the official German representative.
The first official International Congress of Mathematicians was held in Zurich in August 1897. The organizers included such prominent mathematicians as Luigi Cremona, Felix Klein, Gösta Mittag-Leffler, Andrey Markov, and others. The congress was attended by 208 mathematicians from 16 countries, including 12 from Russia and 7 from the US. Only four were women: Iginia Massarini, Vera von Schiff, Charlotte Scott, and Charlotte Wedell.
During the 1900 congress in Paris, France, David Hilbert announced his famous list of 23 unsolved mathematical problems, now termed Hilbert's problems. Moritz Cantor and Vito Volterra gave the two plenary lectures at the start of the congress.
At the 1904 ICM Gyula Kőnig delivered a lecture where he claimed that Cantor's famous continuum hypothesis was false. An error in Kőnig's proof was discovered by Ernst Zermelo soon thereafter. Kőnig's announcement at the congress caused considerable uproar, and Klein had to personally explain |
https://en.wikipedia.org/wiki/Survival%20of%20the%20fittest | "Survival of the fittest" is a phrase that originated from Darwinian evolutionary theory as a way of describing the mechanism of natural selection. The biological concept of fitness is defined as reproductive success. In Darwinian terms, the phrase is best understood as "Survival of the form that will leave the most copies of itself in successive generations."
Herbert Spencer first used the phrase, after reading Charles Darwin's On the Origin of Species, in his Principles of Biology (1864), in which he drew parallels between his own economic theories and Darwin's biological ones: "This survival of the fittest, which I have here sought to express in mechanical terms, is that which Mr. Darwin has called 'natural selection', or the preservation of favoured races in the struggle for life."
Darwin responded positively to Alfred Russel Wallace's suggestion of using Spencer's new phrase "survival of the fittest" as an alternative to "natural selection", and adopted the phrase in The Variation of Animals and Plants Under Domestication published in 1868. In On the Origin of Species, he introduced the phrase in the fifth edition published in 1869, intending it to mean "better designed for an immediate, local environment".
History of the phrase
By his own account, Herbert Spencer described a concept similar to "survival of the fittest" in his 1852 "A Theory of Population". He first used the phrase – after reading Charles Darwin's On the Origin of Species – in his Principles of Biology of 1864 in which he drew parallels between his economic theories and Darwin's biological, evolutionary ones, writing, "This survival of the fittest, which I have here sought to express in mechanical terms, is that which Mr. Darwin has called 'natural selection', or the preservation of favored races in the struggle for life."
In July 1866 Alfred Russel Wallace wrote to Darwin about readers thinking that the phrase "natural selection" personified nature as "selecting" and said this misconceptio |
https://en.wikipedia.org/wiki/Goldstone%20boson | In particle and condensed matter physics, Goldstone bosons or Nambu–Goldstone bosons (NGBs) are bosons that appear necessarily in models exhibiting spontaneous breakdown of continuous symmetries. They were discovered by Yoichiro Nambu in particle physics within the context of the BCS superconductivity mechanism, and subsequently elucidated by Jeffrey Goldstone, and systematically generalized in the context of quantum field theory. In condensed matter physics such bosons are quasiparticles and are known as Anderson–Bogoliubov modes.
These spinless bosons correspond to the spontaneously broken internal symmetry generators, and are characterized by the quantum numbers of these.
They transform nonlinearly (shift) under the action of these generators, and can thus be excited out of the asymmetric vacuum by these generators. Thus, they can be thought of as the excitations of the field in the broken symmetry directions in group space—and are massless if the spontaneously broken symmetry is not also broken explicitly.
If, instead, the symmetry is not exact, i.e. if it is explicitly broken as well as spontaneously broken, then the Nambu–Goldstone bosons are not massless, though they typically remain relatively light; they are then called pseudo-Goldstone bosons or pseudo–Nambu–Goldstone bosons (abbreviated PNGBs).
Goldstone's theorem
Goldstone's theorem examines a generic continuous symmetry which is spontaneously broken; i.e., its currents are conserved, but the ground state is not invariant under the action of the corresponding charges. Then, necessarily, new massless (or light, if the symmetry is not exact) scalar particles appear in the spectrum of possible excitations. There is one scalar particle—called a Nambu–Goldstone boson—for each generator of the symmetry that is broken, i.e., that does not preserve the ground state. The Nambu–Goldstone mode is a long-wavelength fluctuation of the corresponding order parameter.
By virtue of their special properties in co |
https://en.wikipedia.org/wiki/X86%20instruction%20listings | The x86 instruction set refers to the set of instructions that x86-compatible microprocessors support. The instructions are usually part of an executable program, often stored as a computer file and executed on the processor.
The x86 instruction set has been extended several times, introducing wider registers and datatypes as well as new functionality.
x86 integer instructions
Below is the full 8086/8088 instruction set of Intel (81 instructions total). Most if not all of these instructions are available in 32-bit mode; they just operate on 32-bit registers (eax, ebx, etc.) and values instead of their 16-bit (ax, bx, etc.) counterparts. The updated instruction set is also grouped according to architecture (i386, i486, i686) and more generally is referred to as (32-bit) x86 and (64-bit) x86-64 (also known as AMD64).
Original 8086/8088 instructions
Added in specific processors
Added with 80186/80188
Added with 80286
The new instructions added in 80286 add support for x86 protected mode. Some but not all of the instructions are available in real mode as well.
Added with 80386
The 80386 added support for 32-bit operation to the x86 instruction set. This was done by widening the general-purpose registers to 32 bits and introducing the concepts of OperandSize and AddressSize – most instruction forms that would previously take 16-bit data arguments were given the ability to take 32-bit arguments by setting their OperandSize to 32 bits, and instructions that could take 16-bit address arguments were given the ability to take 32-bit address arguments by setting their AddressSize to 32 bits. (Instruction forms that work on 8-bit data continue to be 8-bit regardless of OperandSize. Using a data size of 16 bits will cause only the bottom 16 bits of the 32-bit general-purpose registers to be modified – the top 16 bits are left unchanged.)
The default OperandSize and AddressSize to use for each instruction is given by the D bit of the segment descriptor of the current |
https://en.wikipedia.org/wiki/WSTR-TV | WSTR-TV (channel 64), branded on-air as Star 64 (stylized as STAR64), is a television station in Cincinnati, Ohio, United States, affiliated with MyNetworkTV. It is owned by Deerfield Media, which maintains a local marketing agreement (LMA) with Sinclair Broadcast Group, owner of dual CBS/CW affiliate WKRC-TV (channel 12), for the provision of advertising sales and other services. The two stations share studios on Highland Avenue in the Mount Auburn section of Cincinnati; WSTR's transmitter, Star Tower, is located in the city's College Hill neighborhood.
WSTR-TV began broadcasting in 1980 as WBTI, which broadcast a mix of commercial advertising-supported and subscription television (STV) programs. The STV programming was relegated into overnight hours (before being dropped altogether) at the start of 1985, making way for the station to become an independent station under the callsign WIII. After financial trouble, channel 64 stabilized under ABRY Communications before being purchased by Sinclair in 1996. It was briefly an affiliate of UPN before switching to The WB in 1998 and becoming part of MyNetworkTV in 2006. WKRC-TV produces dedicated morning and late evening newscasts for air on WSTR-TV. The station is one of Cincinnati's two ATSC 3.0 (NextGen TV) transmitters, serving the market's major commercial stations, which each broadcast some of WSTR-TV's subchannels on its behalf.
History
Construction and subscription television years
On June 30, 1977, the Federal Communications Commission (FCC) granted a construction permit to Buford Television of Ohio, Inc., for a new channel 64 television station in Cincinnati, Ohio. WBTI signed on the air on January 28, 1980. It broadcast with one million watts of power and operated from studios on Fishwick Drive in the Bond Hill area; the station's original transmitter was located on Chickasaw Street.
WBTI was conceived and began broadcasting as a hybrid. During the day, it was an advertiser-supported, general-entertainment |
https://en.wikipedia.org/wiki/WRGT-TV | WRGT-TV (channel 45) is a television station in Dayton, Ohio, United States, affiliated with the digital multicast network Dabl. It is owned by Cunningham Broadcasting, which maintains a local marketing agreement (LMA) with Sinclair Broadcast Group, owner of ABC/Fox/MyNetworkTV affiliate WKEF (channel 22), for the provision of certain services. However, Sinclair effectively owns WRGT-TV as the majority of Cunningham's stock is owned by the family of deceased group founder Julian Smith. Both stations share studios on Corporate Place in Miamisburg, while WRGT-TV's transmitter is located off South Gettysburg Avenue in southwest Dayton.
WRGT-TV was a charter Fox affiliate from the network's sign-on in 1986 until 2021.
History
WRGT-TV signed on as an independent station on September 23, 1984, owned by Meridian Communications, based in Pittsburgh. WRGT-TV was Meridian's second station; it had launched WVAH-TV in Charleston, West Virginia, two years earlier. Meridian founded WRGT-TV following a high-stakes "in-contest" competition among four potential owners in the late 1970s. The station ran a general-entertainment format consisting of cartoons, classic sitcoms, recent off-network sitcoms, old movies, drama shows, and sports. On its sign on date, WRGT-TV broadcast 2001: A Space Odyssey, with a stereo simulcast of the audio over WTUE-FM 104.7. It originally used the slogan "Off To a Flying Start", featuring an animated Wright "B" Flyer used in its first promos (the "WRGT" calls are a reference to the Wright brothers).
Prior to its sign on, the only source of non-network programming in Dayton was WTJC (channel 26, now WBDT) a mostly religious station. However, WXIX-TV and WIII-TV (now WSTR-TV), both in Cincinnati, and WTTE in Columbus all reached portions of the Dayton market, and WTTV in Indianapolis was available on cable. Meridian persuaded WTJC's owner, Miami Valley Christian Television, to sell most of that station's non-religious programming to WRGT-TV. For all int |
https://en.wikipedia.org/wiki/KDSM-TV | KDSM-TV (channel 17) is a television station in Des Moines, Iowa, United States, affiliated with the Fox network. The station is owned by Sinclair Broadcast Group, and has studios on Fleur Drive in Des Moines; its transmitter is located in Alleman, Iowa.
History
Prior history of UHF channel 17 in Des Moines
Central Iowa's second television station, KGTV, signed-on in 1953 airing an analog signal on UHF channel 17. At the time, all four networks were shoehorned onto WOI-TV. KGTV was plagued by financial problems from the start. The Des Moines market is fairly large geographically, and at the time UHF signals did not travel very far across long distances. It did not help that very few television sets had UHF capability at the time. As a result, while KGTV should have logically taken the NBC affiliation, that network opted to keep a secondary affiliation with WOI-TV.
The death knell for the station sounded a few months after it went on the air, when Palmer Communications, owner of WHO-AM-FM, won a construction permit for WHO-TV (channel 13). As WHO had been an NBC radio affiliate for almost 30 years, it was a foregone conclusion that WHO-TV would take the NBC affiliation. Channel 17 went dark April 15, 1955. The KGTV calls now reside on the ABC affiliate in San Diego, California.
Early history
Analog UHF channel 17 remained silent until 3:27 p.m. on March 7, 1983, when independent station KCBR (known as "The Great Entertainer") signed-on for "testing" purposes. Normal operations began on March 14, 1983. It was Iowa's first independent station, as well as the first new commercial station in Central Iowa since KRNT-TV (now KCCI) signed-on 28 years earlier. The call letters were picked from the first names of the three original owners: Carl Goldsberry, Bill Trout, and Ray Gazzo. Goldsberry was a Northwestern Bell yellow pages sales representative, while Trout and Gazzo were partners in the Des Moines law firm of Coppola Trout Taha & Gazzo. Trout and Gazzo's law part |
https://en.wikipedia.org/wiki/WNUV | WNUV (channel 54) is a television station in Baltimore, Maryland, United States, affiliated with The CW. It is owned by Cunningham Broadcasting, which maintains a local marketing agreement (LMA) with Sinclair Broadcast Group, owner of Fox/MyNetworkTV affiliate WBFF (channel 45), for the provision of programming and certain services. However, Sinclair effectively owns WNUV, as the majority of Cunningham's stock is owned by the family of deceased group founder Julian Smith. Sinclair also operates TBD affiliate WUTB (channel 24) under a separate shared services agreement with Deerfield Media. The stations share studios on 41st Street off the Jones Falls Expressway on Television Hill in the Woodberry neighborhood of north Baltimore; WBFF and WNUV are also broadcast from the same tower on the hill.
WNUV began broadcasting on July 1, 1982. During the day, it ran specialty programming from the Financial News Network, which was subsidized by its nighttime broadcast of Super TV, a subscription television service that operated in the Washington and Baltimore areas. Super TV peaked at 30,000 Baltimore subscribers in August 1983, but even though the city of Baltimore was late to be wired for cable, the industry suffered a national decline in the mid-1980s, and WNUV ceased airing Super TV on March 31, 1986. In preparation for its closure, the station had begun to recast itself as a general-entertainment independent station as early as 1984. The founding owner and namesake, New-Vision, Inc., sold the station to ABRY Communications in 1989; ABRY upgraded the transmitter and increased the station's visibility with a campaign allowing residents to vote on programming choices.
ABRY attempted to sell WNUV to Glencairn, Ltd.—a forerunner to Cunningham, owned by former Sinclair employee Edwin Edwards and the mother of the Smith children that controlled Sinclair—in 1993. The deal was met with public scrutiny, and though it initially fell apart, ABRY signed an LMA directly with Sinclair |
https://en.wikipedia.org/wiki/WNYO-TV | WNYO-TV (channel 49) is a television station in Buffalo, New York, United States, affiliated with MyNetworkTV. It is owned by Sinclair Broadcast Group alongside Fox affiliate WUTV (channel 29). Both stations share studios on Hertel Avenue near Military Road in Buffalo, while WNYO-TV's transmitter is located on Whitehaven Road (near I-190) in Grand Island, New York.
The construction permit for channel 49 was issued in 1984 and changed hands twice before the station went on the air on September 1, 1987, as WNYB-TV. While TVX Broadcast Group handled much of the station's construction, the company made another purchase that forced it to sell the unbuilt WNYB-TV to remain under national ownership limits. Channel 49's first owner was Aud Enterprises, a division of the Buffalo Sabres hockey team; channel 49 aired Sabres road games and served as the Fox affiliate from 1989 to 1990. It also lost an average of $1 million a year. In 1990, under a deal brokered the previous year, the Sabres games, Fox programming, and syndicated shows on WNYB-TV moved to WUTV, with Tri-State Christian Television (TCT) buying channel 49 to broadcast Christian programming.
TCT sold WNYB-TV to Grant Broadcasting in 1996; the deal included TCT's acquisition of a dormant station on channel 26 in Jamestown, which became the new WNYB. In October 1996, Grant relaunched channel 49 as WNYO-TV, the Buffalo affiliate of The WB. Sinclair purchased the station in 2000, forming a duopoly with WUTV. The station produced its own local newscast from 2004 to 2006 as part of Sinclair's News Central service and then aired local news programming produced by Buffalo NBC affiliate WGRZ from 2006 to 2013. WNYO-TV is Buffalo's ATSC 3.0 (NextGen TV) station; in reciprocal arrangements, other Buffalo TV stations broadcast its subchannels on its behalf while it carries them in the new format.
History
Channel 49 was added to Buffalo in lieu of channel 76 in February 1966 as part of a national overhaul of UHF channel allo |
https://en.wikipedia.org/wiki/WUHF | WUHF (channel 31) is a television station in Rochester, New York, United States, affiliated with the Fox network. It is owned by Sinclair Broadcast Group, which provides certain services to dual ABC/CW affiliate WHAM-TV (channel 13) under a local marketing agreement (LMA) with Deerfield Media. Both stations share studios on West Henrietta Road (NY 15) in Henrietta (with a Rochester mailing address), while WUHF's transmitter is located on Pinnacle Hill on the border between Rochester and Brighton.
History
WUHF began operations on January 27, 1980, as a general entertainment independent station running cartoons, sitcoms (classic and recent), movies, drama series, and religious programs. It was, at the time, the only independent station in the Rochester market.
The station was owned by Malrite and the General Manager was Jerry Carr who was the former The Weather Outside personality. Apparently, by sheer coincidence, the station re-used a call sign which was previously used by a different and unrelated station which operated on the same channel 31, albeit in New York City. The latter station had only used the WUHF calls for its first year of experimental operation (1961–62); it is now Ion Television owned-and-operated station WPXN-TV.
In 1983, former underground cartoonist Brian Bram produced and hosted All Night Live, a program aired live from midnight to 7 a.m. on Fridays and Saturdays. Bram's show was a showcase for regional bands including Personal Effects, Cousin Al and the Relatives, and The Degrads. On October 9, 1986, WUHF became a charter affiliate of Fox for Rochester and was branded as "Fox 31". Most of the religious shows were gone by then. However, WUHF was initially still programmed as an independent station since Fox would only air one program, The Late Show Starring Joan Rivers until April 1987, and even then, would not present an entire week's worth of programming until 1993. In 1989, Act III Broadcasting bought the station from Malrite Communication |
https://en.wikipedia.org/wiki/KVCW | KVCW (channel 33) is a television station in Las Vegas, Nevada, United States, affiliated with The CW and MyNetworkTV. It is owned by Sinclair Broadcast Group alongside NBC affiliate KSNV (channel 3). Both stations share studios on Foremaster Lane in Las Vegas (making them the only major television stations whose operations are based inside the city limits), while KVCW's transmitter is located on Black Mountain, near Henderson (southwest of I-515/US 93/US 95).
History
Early years
On April 22, 1987, the Federal Communications Commission (FCC) issued an original construction permit to 4-A Communications to build a new full-power television station, on UHF channel 33, to serve the Las Vegas market. 4-A Communications, owned by Lawrence and Teri DePaulis, became Channel 33, Inc. (which remained the station's licensee until 2015) in August 1987. The station, known as KFBT, went on the air on July 30, 1989, under a program test authority and was given a license one month later. The station's original transmitter was located in the McCullough Range southwest of Henderson. On July 20, 1990, a family ownership group headed by Daniel "Danny" Koker purchased Channel 33, Inc. Under the Kokers, KFBT was an independent station with a firmly local flavor and soon garnered much acclaim with features such as the scary B-movie showcase Saturday Fright at the Movies, hosted by Count Cool Rider, which aired at 10 p.m. Count Cool Rider was actually Danny Koker II, son of the station president and also one of the station's owners, who has since gone on to become a respected builder of custom motorcycles, as well as a regular expert on the History Channel series Pawn Stars and host of its spinoff, Counting Cars.
As a WB affiliate and return to independence
The station primarily broadcast older movies, sitcoms, and dramas during this era, as well as some Christian religious programs (as the senior Koker was a gospel musician) and professional wrestling (most notably World Class Champion |
https://en.wikipedia.org/wiki/WMYA-TV | WMYA-TV (channel 40) is a television station licensed to Anderson, South Carolina, United States, broadcasting the digital multicast network Dabl to Upstate South Carolina and Western North Carolina. It is owned by Cunningham Broadcasting and operated under a local marketing agreement (LMA) by Sinclair Broadcast Group, owner of Asheville, North Carolina–based ABC/MyNetworkTV affiliate WLOS (channel 13). However, Sinclair effectively owns WMYA-TV, as the majority of Cunningham's stock is owned by the family of deceased group founder Julian Smith. The nominal main studio for WMYA-TV is the WLOS office in Greenville, South Carolina; WMYA-TV's transmitter is located in Fountain Inn, South Carolina.
Founded as WAIM-TV in 1953, the station primarily broadcast local network programming to the Anderson area, serving as an affiliate of ABC and CBS after 1956. However, it lost ABC affiliation at the start of 1979 and failed as an independent station after six months, leading to more than five years of silence. It reemerged as WAXA and had more success serving the market, including two years as the region's first Fox affiliate. However, after the death of its owner in 1987 and more than a year off the air, the station was sold to WLOS for use as a rebroadcaster to reach areas of the Upstate that its Asheville-centric signal could not. In 1995, WLOS converted WAXA to separate programming as independent WFBC-TV. It then became an affiliate of The WB and later MyNetworkTV. Its programming was moved to a subchannel of WLOS in 2021, leaving WMYA to rebroadcast national digital subchannels. In 2022, the station became the ATSC 3.0 (NextGen TV) transmitter for upstate South Carolina; its subchannels are now transmitted by other local stations on its behalf.
History
WAIM-TV
On February 29, 1952, Wilton E. Hall, publisher of the Anderson Independent and Daily Mail (since merged as the Anderson Independent-Mail) and owner of radio stations WAIM (1230 AM) and WCAC-FM (101.1 FM, now WR |
https://en.wikipedia.org/wiki/Encrypting%20File%20System | The Encrypting File System (EFS) on Microsoft Windows is a feature introduced in version 3.0 of NTFS that provides filesystem-level encryption. The technology enables files to be transparently encrypted to protect confidential data from attackers with physical access to the computer.
EFS is available in all versions of Windows except the home versions (see Supported operating systems below) from Windows 2000 onwards. By default, no files are encrypted, but encryption can be enabled by users on a per-file, per-directory, or per-drive basis. Some EFS settings can also be mandated via Group Policy in Windows domain environments.
Cryptographic file system implementations for other operating systems are available, but the Microsoft EFS is not compatible with any of them. See also the list of cryptographic file systems.
Basic ideas
When an operating system is running on a system without file encryption, access to files normally goes through OS-controlled user authentication and access control lists. However, if an attacker gains physical access to the computer, this barrier can be easily circumvented. One way, for example, would be to remove the disk and put it in another computer with an OS installed that can read the filesystem; another, would be to simply reboot the computer from a boot CD containing an OS that is suitable for accessing the local filesystem.
The most widely accepted solution to this is to store the files encrypted on the physical media (disks, USB pen drives, tapes, CDs and so on).
In the Microsoft Windows family of operating systems EFS enables this measure, although on NTFS drives only, and does so using a combination of public key cryptography and symmetric key cryptography to make decrypting the files extremely difficult without the correct key.
However, the cryptography keys for EFS are in practice protected by the user account password, and are therefore susceptible to most password attacks. In other words, the encryption of a file is only |
https://en.wikipedia.org/wiki/WPNT | WPNT (channel 22) is a television station in Pittsburgh, Pennsylvania, United States, affiliated with The CW and MyNetworkTV. It is owned by Sinclair Broadcast Group alongside Fox affiliate WPGH-TV (channel 53). Both stations share studios on Ivory Avenue in the city's Summer Hill section, where WPNT's transmitter is also located.
History
Early history of channel 22
The channel 22 allocation dates back to the 1950s, and was initially acquired by public interest groups as a "backup" plan if the groups were not able to acquire the channel 13 allocation for public television. The groups were in a battle with locally-based Westinghouse Electric Corporation (owners of KDKA radio), who wanted the channel 13 allocation for the proposed KDKA-TV. However, as Westinghouse later gave the groups their blessing to use channel 13 for what would become WQED (Westinghouse bought WDTV from struggling DuMont and transformed that station into KDKA-TV instead), WQED was now stuck with two TV licenses but found use in possibly using channel 22 for educational programs it did not have time to air.
WQED planned to use its proposed WQEX on channel 22, but as fate would have it WENS-TV (channel 16) lost its tower in Reserve Township in a storm on March 11, 1955, leading to a channel sharing agreement with WQED until the tower could be fixed. As WENS-TV was already in a battle for survival competing for the channel 11 license that it would ultimately lose, WQED was able to acquire WENS-TV's assets after that station signed off in 1957 and use its construction permit for channel 22 to relaunch WENS-TV as WQEX on channel 16 instead. (That station is now WINP-TV.) Its channel 22 license and some intellectual property from WENS-TV would eventually be sold to the Commercial Radio Institute (which later became Sinclair Broadcast Group) for the current channel 22, outbidding Cornerstone Television, who ended up with the channel 40 license to launch WPCB-TV.
WPTT-TV
Rising out of the ashes of WE |
https://en.wikipedia.org/wiki/WGWG | WGWG (channel 4) is a television station in Charleston, South Carolina, United States, affiliated with the multicast network MeTV. The station is owned by Howard Stirk Holdings. WGWG's transmitter is located near Awendaw, South Carolina.
From 1962 through 2014, what is now WGWG was the original home of WCIV, and had been Charleston's ABC affiliate since 1996; however, in August 2014, WCIV owner Allbritton Communications was acquired by Sinclair Broadcast Group, owner of MyNetworkTV affiliate WMMP (channel 36) and operator of Fox affiliate WTAT-TV (channel 24, owned by Cunningham Broadcasting). Due to ownership conflicts with WMMP and WTAT, and a recent crackdown on joint sales agreements by the FCC, Sinclair elected to sell the WCIV channel 4 license to Howard Stirk Holdings, and moved WCIV's ABC programming and news operation to a subchannel of WMMP's channel 36 signal. At the same time, the two stations also switched call signs, with WCIV moving to channel 36 and channel 4 becoming the new WMMP, though the MyNetworkTV affiliation remains on channel 36.1 and did not move to channel 4.
The FCC approved HSH Charleston's purchase of channel 4 on December 4, 2014; the call letters became WGWG on March 11, 2015. Howard Stirk Holdings operates WGWG independently of WCIV and WTAT, and has not entered into a local marketing agreement with Sinclair.
History
WGWG began operations on October 23, 1962, as WCIV, the third commercial outlet in Charleston. The original license was granted to WTMA-TV but the call letters were later changed to WCIV before it signed on. It took the NBC affiliation from WCBD-TV (known as WUSN-TV at the time), leaving that station to become a full-time ABC affiliate. The station was originally owned by the Washington Star Company. In 1976, businessman Joe Allbritton bought the Star and sold off the non-television assets in 1978 to form Allbritton Communications.
In May 1994, Birmingham ABC affiliate WBRC was sold to New World Communications, which |
https://en.wikipedia.org/wiki/WUXP-TV | WUXP-TV (channel 30) is a television station in Nashville, Tennessee, United States, affiliated with MyNetworkTV. It is owned by Sinclair Broadcast Group alongside dual Fox/CW affiliate WZTV (channel 17); it is also sister to Dabl affiliate WNAB (channel 58), which Sinclair operates under an outsourcing agreement with Tennessee Broadcasting. The stations share studios on Mainstream Drive along the Cumberland River, while WUXP-TV's transmitter is located along I-24 in Whites Creek.
Channel 30 in Nashville began broadcasting in February 1984 as WCAY-TV. Built by the TVX Broadcast Group, the station competed as Nashville's second independent outlet with WZTV for most of the 1980s. It was the Fox affiliate in Nashville from 1986 to 1990 before selling most of its programming inventory to WZTV amid a tight market. Renamed WXMT in 1989 after being purchased by MT Communications, the station remained the second independent in Nashville and affiliated with UPN in 1995. WZTV began managing channel 30's operations in 1996, a year in which the license was sold and the station renamed WUXP-TV. Sinclair assumed control of the station in 1998, when it acquired WZTV, and purchased it outright in 2000; when UPN folded in 2006, the station switched to MyNetworkTV. WUXP-TV and WNAB are Nashville's two ATSC 3.0 (NextGen TV) stations.
History
The TVX years
In November 1981, the Federal Communications Commission (FCC) designated 13 competing applications for UHF channel 30 in Nashville for comparative hearing. The very large field was stocked with names well-known in other cities, including Carolina Christian Broadcasting, Golden West Broadcasters, and American Television and Communications (the cable TV division of Time, Inc.). By January 1982, only five of the applicants were still in the running for the construction permit: Television Corporation of Tennessee, a company headquartered in Norfolk, Virginia, in which mayor Richard Fulton became a minority investor; Music City Thirty, |
https://en.wikipedia.org/wiki/WNAB | WNAB (channel 58) is a television station in Nashville, Tennessee, United States, affiliated with the digital multicast network Dabl. It is owned by Tennessee Broadcasting, which maintains an outsourcing agreement with Sinclair Broadcast Group, owner of Fox/CW affiliate WZTV (channel 17) and MyNetworkTV affiliate WUXP-TV (channel 30), for the provision of certain services. The stations share studios on Mainstream Drive along the Cumberland River, while WNAB's transmitter is located along I-24 in Whites Creek.
History
As a WB affiliate
In 1987, Ruth Payne Carman was awarded a construction permit to build a new television station on channel 58 in Nashville, which took the call letters WNAB. It would be another eight years before it began broadcasting on November 29, 1995, as the WB affiliate for the Nashville market. Prior to WNAB's debut, WB programming was only available on Nashville area cable and satellite providers either through Chicago-based national superstation WGN, or by Cookeville-based WKZX (channel 28, now Ion Television owned-and-operated station WNPX-TV), which served the eastern part of the market. Three months after launching the station, Speer Communications, a company founded by Home Shopping Network co-founder Roy Speer; it was from Speer's studios in a former Sam's Club building on Dickerson Road in Nashville that the station had launched.
Offering five hours of live, locally produced programming each weekday, WNAB was quickly a hit among Nashville viewers, although the station lacked cable carriage in many of the suburbs. Controversial former Nashville mayor and U.S. congressman Bill Boner hosted an hour-long interview/call-in show, Prime Talk each weeknight. Its follow-up, Sports Talk, featured Nashville Banner sportswriter Greg Pogue and popular radio personality George Plaster showing highlights and taking calls about the day's sports action. On Friday nights in the fall, Sports Talk was extended by an hour and became Nashville's first tele |
https://en.wikipedia.org/wiki/Outer%20automorphism%20group | In mathematics, the outer automorphism group of a group, , is the quotient, , where is the automorphism group of and ) is the subgroup consisting of inner automorphisms. The outer automorphism group is usually denoted . If is trivial and has a trivial center, then is said to be complete.
An automorphism of a group that is not inner is called an outer automorphism. The cosets of with respect to outer automorphisms are then the elements of ; this is an instance of the fact that quotients of groups are not, in general, (isomorphic to) subgroups. If the inner automorphism group is trivial (when a group is abelian), the automorphism group and outer automorphism group are naturally identified; that is, the outer automorphism group does act on the group.
For example, for the alternating group, , the outer automorphism group is usually the group of order 2, with exceptions noted below. Considering as a subgroup of the symmetric group, , conjugation by any odd permutation is an outer automorphism of or more precisely "represents the class of the (non-trivial) outer automorphism of ", but the outer automorphism does not correspond to conjugation by any particular odd element, and all conjugations by odd elements are equivalent up to conjugation by an even element.
Structure
The Schreier conjecture asserts that is always a solvable group when is a finite simple group. This result is now known to be true as a corollary of the classification of finite simple groups, although no simpler proof is known.
As dual of the center
The outer automorphism group is dual to the center in the following sense: conjugation by an element of is an automorphism, yielding a map . The kernel of the conjugation map is the center, while the cokernel is the outer automorphism group (and the image is the inner automorphism group). This can be summarized by the exact sequence
Applications
The outer automorphism group of a group acts on conjugacy classes, and accordingly on the charact |
https://en.wikipedia.org/wiki/Television%20set | A television set or television receiver (more commonly called TV, TV set, television, telly, or tele) is an electronic device for the purpose of viewing and hearing television broadcasts, or as a computer monitor. It combines a tuner, display, and loudspeakers. Introduced in the late 1920s in mechanical form, television sets became a popular consumer product after World War II in electronic form, using cathode ray tube (CRT) technology. The addition of color to broadcast television after 1953 further increased the popularity of television sets in the 1960s, and an outdoor antenna became a common feature of suburban homes. The ubiquitous television set became the display device for the first recorded media for consumer use in the 1970s, such as Betamax, VHS; these were later succeeded by DVD. It has been used as a display device since the first generation of home computers (e.g. Timex Sinclair 1000) and dedicated video game consoles (e.g. Atari) in the 1980s. By the early 2010s, flat-panel television incorporating liquid-crystal display (LCD) technology, especially LED-backlit LCD technology, largely replaced CRT and other display technologies. Modern flat panel TVs are typically capable of high-definition display (720p, 1080i, 1080p, 4K, 8K) and can also play content from a USB device. Starting in the late 2010s, most flat panel TVs began to offer 4K and 8K resolutions.
History
Early television
Mechanical televisions were commercially sold from 1928 to 1934 in the United Kingdom, France, the United States, and the Soviet Union. The earliest commercially made televisions were radios with the addition of a television device consisting of a neon tube behind a mechanically spinning disk with a spiral of apertures that produced a red postage-stamp size image, enlarged to twice that size by a magnifying glass. The Baird "Televisor" (sold in 1930–1933 in the UK) is considered the first mass-produced television, selling about a thousand units.
In 1926, Kenjiro Takayanag |
https://en.wikipedia.org/wiki/Adriaan%20van%20Roomen | Adriaan van Roomen (29 September 1561 – 4 May 1615), also known as Adrianus Romanus, was a mathematician, professor of medicine and medical astronomer from the Duchy of Brabant in the Habsburg Netherlands who was active throughout Central Europe in the late 16th and early 17th centuries. As a mathematician he worked in algebra, trigonometry and geometry; and on the decimal expansion of π. He solved the Problem of Apollonius using a new method that involved intersecting hyperbolas. He also wrote on the Gregorian calendar reform.
Life
Van Roomen was born in Leuven, the son of Adriaan Van Roomen and Maria Van Den Daele. He was educated partly in Leuven and partly After studying at the Jesuit College in Cologne, also attending the University of Cologne where he began his study of medicine. He also briefly studied medicine at Leuven University. Roomen was professor of mathematics and medicine at Louvain from 1586 to 1592. He met Kepler, and discussed with François Viète two questions about equations and tangencies. He then spent some time in Italy, particularly with Clavius in Rome in 1585. His publication of 1595, Parvum theatrum urbium, contained Latin verse on the cities of Italy (possibly written by Thomas Edwards).
In June 1593 Van Roomen became the inaugural professor of medicine at the newly refounded University of Würzburg. He was also appointed physician in ordinary to the court of Rudolf II. From around 1595 to 1603 he produced calendars, almanacs and prognostications published under the patronage of Julius Echter, prince-bishop of Würzburg. At the same time, he served as mathematician of the king of Poland and become famous for the computation of the value of Pi to sixteen decimals, surpassing François Viète who had arrived at ten digits. After being widowed he was ordained to the priesthood in 1604 and on 8 October 1608 was installed as a canon of the collegiate church of St John the Evangelist in Würzburg.
His Mathesis Polemica, published in Frankfurt in |
https://en.wikipedia.org/wiki/Meridian%20%28astronomy%29 | In astronomy, the meridian is the great circle passing through the celestial poles, as well as the zenith and nadir of an observer's location. Consequently, it contains also the north and south points on the horizon, and it is perpendicular to the celestial equator and horizon. Meridians, celestial and geographical, are determined by the pencil of planes passing through the Earth's rotation axis. For a location not at a geographical pole, there is a unique meridian plane in this axial-pencil through that location. The intersection of this plane with Earth's surface is the geographical meridian, and the intersection of the plane with the celestial sphere is the celestial meridian for that location and time.
There are several ways to divide the meridian into semicircles. In the horizontal coordinate system, the observer's meridian is divided into halves terminated by the horizon's north and south points. The observer's upper meridian passes through the zenith while the lower meridian passes through the nadir. Another way, the meridian is divided into the local meridian, the semicircle that contains the observer's zenith and both celestial poles, and the opposite semicircle, which contains the nadir and both poles.
On any given (sidereal) day/night, a celestial object will appear to drift across, or transit, the observer's upper meridian as Earth rotates, since the meridian is fixed to the local horizon. At culmination, the object contacts the upper meridian and reaches its highest point in the sky. An object's right ascension and the local sidereal time can be used to determine the time of its culmination (see hour angle).
The term meridian comes from the Latin meridies, which means both "midday" and "south", as the celestial equator appears to tilt southward from the Northern Hemisphere.
See also
Meridian (geography)
Prime meridian (planets)
Prime vertical, the vertical circle perpendicular to a meridian
Longitude (planets)
References
Millar, William (2006) |
https://en.wikipedia.org/wiki/Meridian%20%28geography%29 | In geography and geodesy, a meridian is the locus connecting points of equal longitude, which is the angle (in degrees or other units) east or west of a given prime meridian (currently, the IERS Reference Meridian). In other words, it is a line of longitude. The position of a point along the meridian is given by that longitude and its latitude, measured in angular degrees north or south of the Equator. On a Mercator projection or on a Gall-Peters projection, each meridian is perpendicular to all circles of latitude. A meridian is half of a great circle on Earth's surface. The length of a meridian on a modern ellipsoid model of Earth (WGS 84) has been estimated as .
Pre-Greenwich
The first prime meridian was set by Eratosthenes in 200 BCE. This prime meridian was used to provide measurement of the earth, but had many problems because of the lack of latitude measurement. Many years later around the 19th century there were still concerns of the prime meridian. Multiple locations for the geographical meridian meant that there was inconsistency, because each country had their own guidelines for where the prime meridian was located.
Etymology
The term meridian comes from the Latin meridies, meaning "midday"; the subsolar point passes through a given meridian at solar noon, midway between the times of sunrise and sunset on that meridian. Likewise, the Sun crosses the celestial meridian at the same time. The same Latin stem gives rise to the terms a.m. (ante meridiem) and p.m. (post meridiem) used to disambiguate hours of the day when utilizing the 12-hour clock.
International Meridian Conference
Because of a growing international economy, there was a demand for a set international prime meridian to make it easier for worldwide traveling which would, in turn, enhance international trading across countries. As a result, a Conference was held in 1884, in Washington, D.C. Twenty-six countries were present at the International Meridian Conference to vote on an internation |
https://en.wikipedia.org/wiki/Stefan%20Mazurkiewicz | Stefan Mazurkiewicz (25 September 1888 – 19 June 1945) was a Polish mathematician who worked in mathematical analysis, topology, and probability. He was a student of Wacław Sierpiński and a member of the Polish Academy of Learning (PAU). His students included Karol Borsuk, Bronisław Knaster, Kazimierz Kuratowski, Stanisław Saks, and Antoni Zygmund. For a time Mazurkiewicz was a professor at the University of Paris; however, he spent most of his career as a professor at the University of Warsaw.
The Hahn–Mazurkiewicz theorem, a basic result on curves prompted by the phenomenon of space-filling curves, is named for Mazurkiewicz and Hans Hahn. His 1935 paper Sur l'existence des continus indécomposables is generally considered the most elegant piece of work in point-set topology.
During the Polish–Soviet War (1919–21), Mazurkiewicz as early as 1919 broke the most common Russian cipher for the Polish General Staff's cryptological agency. Thanks to this, orders issued by Soviet commander Mikhail Tukhachevsky's staff were known to Polish Army leaders. This contributed substantially, perhaps decisively, to Polish victory at the critical Battle of Warsaw and possibly to Poland's survival as an independent country.
See also
Biuro Szyfrów
List of Polish mathematicians
External links
1888 births
1945 deaths
Warsaw School of Mathematics
People from Warsaw Governorate
Polish cryptographers
Topologists
Academic staff of the University of Paris
Academic staff of the University of Warsaw
Mathematical analysts
Cipher Bureau (Poland)
University of Warsaw alumni |
https://en.wikipedia.org/wiki/NewWave | NewWave is a discontinued object-oriented graphical desktop environment and office productivity tool for PCs running early versions of Microsoft Windows (beginning with 2.0). It was developed by Hewlett-Packard and introduced commercially in 1988. It was used on the HP Vectras and other IBM compatible PCs running Windows.
From a user perspective NewWave ran on top of Windows and completely replaced the standard Windows Desktop and Program Manager user interface with its own object-oriented desktop interface.
HP promoted NewWave until the release of Windows 95, at which time further development of the product ceased due to incompatibility with the new operating system. The NewWave GUI (together with the contemporaneous NeXTSTEP GUI) introduced the shaded "3-D look and feel" that was later widely adopted.
HP encouraged independent software vendors to produce versions of applications which took advantage of NewWave functionality, allowing their data to be handled as objects instead of files. One early example was Samna Corporation (later acquired by Lotus) who produced an edition of their Microsoft Windows word processor Ami Pro entitled "Ami Pro for NewWave". On June 20, 1988 Microsoft Corporation and Hewlett-Packard issued a press release announcing the inclusion of NewWave support in an up-coming release Microsoft Excel.
NewWave featured icons, scheduled scripts in the form of "agents", and "hot connects."
HP incorporated NewWave into their multi-platform office automation offerings running under their proprietary MPE and HP-UX (UNIX) minicomputer operating systems. They developed NewWave versions of key email, database, document management, personal productivity, communications and network management tools and branded all related solutions under the “HP NewWave Office” banner. Prior to the integration of HP NewWave this solution set had been known as “Business System Plus”. The “NewWave Office” term had been used previously to describe the main NewWave user de |
https://en.wikipedia.org/wiki/Feynman%E2%80%93Kac%20formula | The Feynman–Kac formula, named after Richard Feynman and Mark Kac, establishes a link between parabolic partial differential equations (PDEs) and stochastic processes. In 1947, when Kac and Feynman were both Cornell faculty, Kac attended a presentation of Feynman's and remarked that the two of them were working on the same thing from different directions. The Feynman–Kac formula resulted, which proves rigorously the real-valued case of Feynman's path integrals. The complex case, which occurs when a particle's spin is included, is still an open question.
It offers a method of solving certain partial differential equations by simulating random paths of a stochastic process. Conversely, an important class of expectations of random processes can be computed by deterministic methods.
Theorem
Consider the partial differential equation
defined for all and , subject to the terminal condition
where are known functions, is a parameter, and is the unknown. Then the Feynman–Kac formula tells us that the solution can be written as a conditional expectationunder the probability measure such that is an Itô process driven by the equation
with is a Wiener process (also called Brownian motion) under , and the initial condition for is .
Intuitive interpretation
Suppose we have a particle moving according to the diffusion processLet the particle incur "cost" at a rate of at location at time . Let it incur a final cost at .
Also, allow the particle to decay. If the particle is at location at time , then it decays with rate . After the particle has decayed, all future cost is zero.
Then, is the expected cost-to-go, if the particle starts at .
Partial proof
A proof that the above formula is a solution of the differential equation is long, difficult and not presented here. It is however reasonably straightforward to show that, if a solution exists, it must have the above form. The proof of that lesser result is as follows:
Let be the solution to the above partial |
https://en.wikipedia.org/wiki/Abstract%20nonsense | In mathematics, abstract nonsense, general abstract nonsense, generalized abstract nonsense, and general nonsense are nonderogatory terms used by mathematicians to describe long, theoretical parts of a proof they skip over when readers are expected to be familiar with them. These terms are mainly used for abstract methods related to category theory and homological algebra. More generally, "abstract nonsense" may refer to a proof that relies on category-theoretic methods, or even to the study of category theory itself.
Background
Roughly speaking, category theory is the study of the general form, that is, categories of mathematical theories, without regard to their content. As a result, mathematical proofs that rely on category-theoretic ideas often seem out-of-context, somewhat akin to a non sequitur. Authors sometimes dub these proofs "abstract nonsense" as a light-hearted way of alerting readers to their abstract nature. Labeling an argument "abstract nonsense" is usually not intended to be derogatory, and is instead used jokingly, in a self-deprecating way, affectionately, or even as a compliment to the generality of the argument.
Certain ideas and constructions in mathematics share a uniformity throughout many domains, unified by category theory. Typical methods include the use of classifying spaces and universal properties, use of the Yoneda lemma, natural transformations between functors, and diagram chasing.
When an audience can be assumed to be familiar with the general form of such arguments, mathematicians will use the expression "Such and such is true by abstract nonsense" rather than provide an elaborate explanation of particulars. For example, one might say that "By abstract nonsense, products are unique up to isomorphism when they exist", instead of arguing about how these isomorphisms can be derived from the universal property that defines the product. This allows one to skip proof details that can be considered trivial or not providing much insi |
https://en.wikipedia.org/wiki/High%20memory | High memory is the part of physical memory in a computer which is not directly mapped by the page tables of its operating system kernel. The phrase is also sometimes used as shorthand for the High Memory Area, which is a different concept entirely.
Some operating system kernels, such as Linux, divide their virtual address space into two regions, devoting the larger to user space and the smaller to the kernel. In current 32-bit x86 computers, this commonly (although does not have to, as this is a configurable option) takes the form of a 3GB/1GB split of the 4 GB address space, so kernel virtual addresses start at 0xC0000000 and go to 0xFFFFFFFF. The lower 896 MB, from 0xC0000000 to 0xF7FFFFFF, is directly mapped to the kernel physical address space, and the remaining 128 MB, from 0xF8000000 to 0xFFFFFFFF, is used on demand by the kernel to be mapped to high memory. When in user mode, translations are only effective for the first region, thus protecting the kernel from user programs, but when in kernel mode, translations are effective for both regions, thus giving the kernel an easy way to refer to the buffers of processes—it just uses the process' own mappings.
However, if the kernel needs to refer to physical memory for which a userspace translation has not already been provided, it has only 1 GB (for example) of virtual memory to use. On computers with a lot of physical memory, this can mean that there exists memory that the kernel cannot refer to directly—this is called high memory. When the kernel wishes to address high memory, it creates a mapping on the fly and destroys the mapping when done, which incurs a performance penalty.
See also
Physical Address Extension (PAE)
References
External links
High Memory
Virtual Memory I: the problem
X86 architecture
X86 memory management
Linux kernel |
https://en.wikipedia.org/wiki/Hugo%20Hadwiger | Hugo Hadwiger (23 December 1908 in Karlsruhe, Germany – 29 October 1981 in Bern, Switzerland) was a Swiss mathematician, known for his work in geometry, combinatorics, and cryptography.
Biography
Although born in Karlsruhe, Germany, Hadwiger grew up in Bern, Switzerland. He did his undergraduate studies at the University of Bern, where he majored in mathematics but also studied physics and actuarial science. He continued at Bern for his graduate studies, and received his Ph.D. in 1936 under the supervision of Willy Scherrer. He was for more than forty years a professor of mathematics at Bern.
Mathematical concepts named after Hadwiger
Hadwiger's theorem in integral geometry classifies the isometry-invariant valuations on compact convex sets in d-dimensional Euclidean space. According to this theorem, any such valuation can be expressed as a linear combination of the intrinsic volumes; for instance, in two dimensions, the intrinsic volumes are the area, the perimeter, and the Euler characteristic.
The Hadwiger–Finsler inequality, proven by Hadwiger with Paul Finsler, is an inequality relating the side lengths and area of any triangle in the Euclidean plane. It generalizes Weitzenböck's inequality and was generalized in turn by Pedoe's inequality. In the same 1937 paper in which Hadwiger and Finsler published this inequality, they also published the Finsler–Hadwiger theorem on a square derived from two other squares that share a vertex.
Hadwiger's name is also associated with several important unsolved problems in mathematics:
The Hadwiger conjecture in graph theory, posed by Hadwiger in 1943 and called by “one of the deepest unsolved problems in graph theory,” describes a conjectured connection between graph coloring and graph minors. The Hadwiger number of a graph is the number of vertices in the largest clique that can be formed as a minor in the graph; the Hadwiger conjecture states that this is always at least as large as the chromatic number.
The Hadwiger c |
https://en.wikipedia.org/wiki/Algebraic%20geometry%20and%20analytic%20geometry | In mathematics, algebraic geometry and analytic geometry are two closely related subjects. While algebraic geometry studies algebraic varieties, analytic geometry deals with complex manifolds and the more general analytic spaces defined locally by the vanishing of analytic functions of several complex variables. The deep relation between these subjects has numerous applications in which algebraic techniques are applied to analytic spaces and analytic techniques to algebraic varieties.
Main statement
Let X be a projective complex algebraic variety. Because X is a complex variety, its set of complex points X(C) can be given the structure of a compact complex analytic space. This analytic space is denoted Xan. Similarly, if is a sheaf on X, then there is a corresponding sheaf on Xan. This association of an analytic object to an algebraic one is a functor. The prototypical theorem relating X and Xan says that for any two coherent sheaves and on X, the natural homomorphism:
is an isomorphism. Here is the structure sheaf of the algebraic variety X and is the structure sheaf of the analytic variety Xan. In other words, the category of coherent sheaves on the algebraic variety X is equivalent to the category of analytic coherent sheaves on the analytic variety Xan, and the equivalence is given on objects by mapping to . (Note in particular that itself is coherent, a result known as the Oka coherence theorem, and also, it was proved in “Faisceaux Algebriques Coherents” () that the structure sheaf of the algebraic variety is coherent.)
Another important statement is as follows: For any coherent sheaf on an algebraic variety X the homomorphisms
are isomorphisms for all qs. This means that the q-th cohomology group on X is isomorphic to the cohomology group on Xan.
The theorem applies much more generally than stated above (see the formal statement below). It and its proof have many consequences, such as Chow's theorem, the Lefschetz principle and Kodair |
https://en.wikipedia.org/wiki/HP-IL | The HP-IL (Hewlett-Packard Interface Loop), was a short-range interconnection bus or network introduced by Hewlett-Packard in the early 1980s. It enabled many devices such as printers, plotters, displays, storage devices (floppy disk drives and tape drives), test equipment, etc. to be connected to programmable calculators such as the HP-41C, HP-71B and HP-75C/D, the 80-series and HP-110 computers, as well as generic ISA bus based PCs.
Principles
As its name implies, an HP-IL network formed a loop (i.e. it was a Ring network): each device in the loop had a pair of two-wire connections, one designated in, which received messages from the previous device in the loop; and one designated out, which delivered messages to the next device in the loop. One device on the loop is designated the controller, and manages all other devices on the loop. HP-IL cables utilize a unique two-pin connector design with polarizing "D"-shaped shells, and can be connected together without further adapters to extend their length.
HP-IL uses a token passing protocol for media access control: messages are passed from one device to the next until they return to the originator. When the loop is initialized, the controller sends an "Auto Address 1" message to the first device; that device (and each subsequent device) takes the number in the message it receives as its own address, and then forwards the message with the address incremented to the next device. When the "Auto Address n" message finally returns to the controller, it can tell how many devices are on the loop (n-1). Up to 31 devices can be addressed using this method. Once addresses are assigned, the controller can then assign "talker" or "listener" roles to any device on the loop. By addressing each device in turn, and using the "Send Accessory ID" message, the controller can determine the role and capability of each device on the loop.
When the controller assigns listener role to a device, that device accepts and processes data re |
https://en.wikipedia.org/wiki/Arithmetic%20group | In mathematics, an arithmetic group is a group obtained as the integer points of an algebraic group, for example They arise naturally in the study of arithmetic properties of quadratic forms and other classical topics in number theory. They also give rise to very interesting examples of Riemannian manifolds and hence are objects of interest in differential geometry and topology. Finally, these two topics join in the theory of automorphic forms which is fundamental in modern number theory.
History
One of the origins of the mathematical theory of arithmetic groups is algebraic number theory. The classical reduction theory of quadratic and Hermitian forms by Charles Hermite, Hermann Minkowski and others can be seen as computing fundamental domains for the action of certain arithmetic groups on the relevant symmetric spaces. The topic was related to Minkowski's geometry of numbers and the early development of the study of arithmetic invariant of number fields such as the discriminant. Arithmetic groups can be thought of as a vast generalisation of the unit groups of number fields to a noncommutative setting.
The same groups also appeared in analytic number theory as the study of classical modular forms and their generalisations developed. Of course the two topics were related, as can be seen for example in Langlands' computation of the volume of certain fundamental domains using analytic methods. This classical theory culminated with the work of Siegel, who showed the finiteness of the volume of a fundamental domain in many cases.
For the modern theory to begin foundational work was needed, and was provided by the work of Armand Borel, André Weil, Jacques Tits and others on algebraic groups. Shortly afterwards the finiteness of covolume was proven in full generality by Borel and Harish-Chandra. Meanwhile, there was progress on the general theory of lattices in Lie groups by Atle Selberg, Grigori Margulis, David Kazhdan, M. S. Raghunathan and others. The state of t |
https://en.wikipedia.org/wiki/Internet%20Connection%20Sharing | Internet Connection Sharing (ICS) is a Windows service that enables one Internet-connected computer to share its Internet connection with other computers on a local area network (LAN). The computer that shares its Internet connection serves as a gateway device, meaning that all traffic between other computers and the Internet go through this computer. ICS provides Dynamic Host Configuration Protocol (DHCP) and network address translation (NAT) services for the LAN computers.
ICS was a feature of Windows 98 SE and all versions of Windows released for personal computers thereafter.
Operation
ICS routes TCP/IP packets from a small LAN to the Internet. ICS provides NAT services, mapping individual IP addresses of local computers to unused port numbers in the sharing computer. Because of the nature of the NAT, IP addresses on the local computer are not visible on the Internet. All packets leaving or entering the LAN are sent from or to the IP address of the external adapter on the ICS host computer.
Typically, ICS can be used when there are several network interface cards installed on the host computer. In this case, ICS makes an Internet connection available on one network interface to be accessible to one other interface that is explicitly designated as the private network. ICS can also share dial-up (including PSTN, ISDN and ADSL connections), PPPoE and VPN connections.
Starting with Windows XP, ICS is integrated with UPnP, allowing remote discovery and control of the ICS host. It also has a Quality of Service Packet Scheduler component. When an ICS client is on a relatively fast network and the ICS host is connected to the Internet through a slow link, Windows may incorrectly calculate the optimal TCP receive window size based on the speed of the link between the client and the ICS host, potentially affecting traffic from the sender adversely. The ICS QoS component sets the TCP receive window size to the same as it would be if the receiver were directly connecte |
https://en.wikipedia.org/wiki/Ecstasy%20%28emotion%29 | Ecstasy () is a subjective experience of total involvement of the subject with an object of their awareness. In classical Greek literature, it refers to removal of the mind or body "from its normal place of function."
Total involvement with an object of interest is not an ordinary experience. Ecstasy is an example of an altered state of consciousness characterized by diminished awareness of other objects or the total lack of the awareness of surroundings and everything around the object. The word is also used to refer to any heightened state of consciousness or intensely pleasant experience. It is also used more specifically to denote states of awareness of non-ordinary mental spaces, which may be perceived as spiritual (the latter type of ecstasy often takes the form of religious ecstasy).
Description
From a psychological perspective, ecstasy is a loss of self-control and sometimes a temporary loss of consciousness, which is often associated with religious mysticism, sexual intercourse and the use of certain drugs. For the duration of the ecstasy the ecstatic is out of touch with ordinary life and is capable neither of communication with other people nor of undertaking normal actions. The experience can be brief in physical time, or it can go on for hours. Subjective perception of time, space or self may strongly change or disappear during ecstasy. For instance, if one is concentrating on a physical task, then any intellectual thoughts may cease. On the other hand, making a spirit journey in an ecstatic trance involves the cessation of voluntary bodily movement.
Types
Ecstasy can be deliberately induced using religious or creative activities, meditation, music, dancing, breathing exercises, physical exercise, sexual intercourse or consumption of psychotropic drugs. The particular technique that an individual uses to induce ecstasy is usually also associated with that individual's particular religious and cultural traditions. Sometimes an ecstatic experience ta |
https://en.wikipedia.org/wiki/Library%20%28biology%29 | In molecular biology, a library is a collection of DNA fragments that is stored and propagated in a population of micro-organisms through the process of molecular cloning. There are different types of DNA libraries, including cDNA libraries (formed from reverse-transcribed RNA), genomic libraries (formed from genomic DNA) and randomized mutant libraries (formed by de novo gene synthesis where alternative nucleotides or codons are incorporated). DNA library technology is a mainstay of current molecular biology, genetic engineering, and protein engineering, and the applications of these libraries depend on the source of the original DNA fragments. There are differences in the cloning vectors and techniques used in library preparation, but in general each DNA fragment is uniquely inserted into a cloning vector and the pool of recombinant DNA molecules is then transferred into a population of bacteria (a Bacterial Artificial Chromosome or BAC library) or yeast such that each organism contains on average one construct (vector + insert). As the population of organisms is grown in culture, the DNA molecules contained within them are copied and propagated (thus, "cloned").
Terminology
The term "library" can refer to a population of organisms, each of which carries a DNA molecule inserted into a cloning vector, or alternatively to the collection of all of the cloned vector molecules.
cDNA libraries
A cDNA library represents a sample of the mRNA purified from a particular source (either a collection of cells, a particular tissue, or an entire organism), which has been converted back to a DNA template by the use of the enzyme reverse transcriptase. It thus represents the genes that were being actively transcribed in that particular source under the physiological, developmental, or environmental conditions that existed when the mRNA was purified. cDNA libraries can be generated using techniques that promote "full-length" clones or under conditions that generate shorter f |
https://en.wikipedia.org/wiki/Smith%20number | In number theory, a Smith number is a composite number for which, in a given number base, the sum of its digits is equal to the sum of the digits in its prime factorization in the same base. In the case of numbers that are not square-free, the factorization is written without exponents, writing the repeated factor as many times as needed.
Smith numbers were named by Albert Wilansky of Lehigh University, as he noticed the property in the phone number (493-7775) of his brother-in-law Harold Smith:
4937775 = 3 · 5 · 5 · 65837
while
4 + 9 + 3 + 7 + 7 + 7 + 5 = 3 + 5 + 5 + (6 + 5 + 8 + 3 + 7)
in base 10.
Mathematical definition
Let be a natural number. For base , let the function be the digit sum of in base . A natural number with prime factorisation
is a Smith number if
Here the exponent is the multiplicity of as a prime factor of (also known as the p-adic valuation of ).
For example, in base 10, 378 = 21 · 33 · 71 is a Smith number since 3 + 7 + 8 = 2 · 1 + 3 · 3 + 7 · 1, and 22 = 21 · 111 is a Smith number, because 2 + 2 = 2 · 1 + (1 + 1) · 1.
The first few Smith numbers in base 10 are
4, 22, 27, 58, 85, 94, 121, 166, 202, 265, 274, 319, 346, 355, 378, 382, 391, 438, 454, 483, 517, 526, 535, 562, 576, 588, 627, 634, 636, 645, 648, 654, 663, 666, 690, 706, 728, 729, 762, 778, 825, 852, 861, 895, 913, 915, 922, 958, 985.
Properties
W.L. McDaniel in 1987 proved that there are infinitely many Smith numbers.
The number of Smith numbers in base 10 below 10n for n = 1, 2, ... is given by
1, 6, 49, 376, 3294, 29928, 278411, 2632758, 25154060, 241882509, ... .
Two consecutive Smith numbers (for example, 728 and 729, or 2964 and 2965) are called Smith brothers. It is not known how many Smith brothers there are. The starting elements of the smallest Smith n-tuple (meaning n consecutive Smith numbers) in base 10 for n = 1, 2, ... are
4, 728, 73615, 4463535, 15966114, 2050918644, 164736913905, ... .
Smith numbers can be constructed from factored repunits. , |
https://en.wikipedia.org/wiki/Key%20management | Key management refers to management of cryptographic keys in a cryptosystem. This includes dealing with the generation, exchange, storage, use, crypto-shredding (destruction) and replacement of keys. It includes cryptographic protocol design, key servers, user procedures, and other relevant protocols.
Key management concerns keys at the user level, either between users or systems. This is in contrast to key scheduling, which typically refers to the internal handling of keys within the operation of a cipher.
Successful key management is critical to the security of a cryptosystem. It is the more challenging side of cryptography in a sense that it involves aspects of social engineering such as system policy, user training, organizational and departmental interactions, and coordination between all of these elements, in contrast to pure mathematical practices that can be automated.
Types of keys
Cryptographic systems may use different types of keys, with some systems using more than one. These may include symmetric keys or asymmetric keys. In a symmetric key algorithm the keys involved are identical for both encrypting and decrypting a message. Keys must be chosen carefully, and distributed and stored securely. Asymmetric keys, also known as public keys, in contrast are two distinct keys that are mathematically linked. They are typically used together to communicate. Public key infrastructure (PKI), the implementation of public key cryptography, requires an organization to establish an infrastructure to create and manage public and private key pairs along with digital certificates.
Inventory
The starting point in any certificate and private key management strategy is to create a comprehensive inventory of all certificates, their locations and responsible parties. This is not a trivial matter because certificates from a variety of sources are deployed in a variety of locations by different individuals and teams - it's simply not possible to rely on a list from a s |
https://en.wikipedia.org/wiki/Halton%20sequence | In statistics, Halton sequences are sequences used to generate points in space for numerical methods such as Monte Carlo simulations. Although these sequences are deterministic, they are of low discrepancy, that is, appear to be random for many purposes. They were first introduced in 1960 and are an example of a quasi-random number sequence. They generalize the one-dimensional van der Corput sequences.
Example of Halton sequence used to generate points in (0, 1) × (0, 1) in R2
The Halton sequence is constructed according to a deterministic method that uses coprime numbers as its bases. As a simple example, let's take one dimension of the Halton sequence to be based on 2 and the other on 3. To generate the sequence for 2, we start by dividing the interval (0,1) in half, then in fourths, eighths, etc., which generates
,
, ,
, , , ,
, ,...
Equivalently, the nth number of this sequence is the number n written in binary representation, inverted, and written after the decimal point. This is true for any base. As an example, to find the sixth element of the above sequence, we'd write 6 = 1*2 + 1*2 + 0*2 = 110, which can be inverted and placed after the decimal point to give 0.011 = 0*2 + 1*2 + 1*2 = . So the sequence above is the same as
0.1, 0.01, 0.11, 0.001, 0.101, 0.011, 0.111, 0.0001, 0.1001,...
To generate the sequence for 3, we divide the interval (0,1) in thirds, then ninths, twenty-sevenths, etc., which generates
, , , , , , , , ,...
When we pair them up, we get a sequence of points in a unit square:
(, ), (, ), (, ), (, ), (, ), (, ), (, ), (, ), (, ).
Even though standard Halton sequences perform very well in low dimensions, correlation problems have been noted between sequences generated from higher primes. For example, if we started with the primes 17 and 19, the first 16 pairs of points: (, ), (, ), (, ) ... (, ) would have perfect linear correlation. To avoid this, it is common to drop the first 20 entries, or some other predetermi |
https://en.wikipedia.org/wiki/Golgi%27s%20method | Golgi's method is a silver staining technique that is used to visualize nervous tissue under light microscopy. The method was discovered by Camillo Golgi, an Italian physician and scientist, who published the first picture made with the technique in 1873. It was initially named the black reaction (la reazione nera) by Golgi, but it became better known as the Golgi stain or later, Golgi method.
Golgi staining was used by Spanish neuroanatomist Santiago Ramón y Cajal (1852–1934) to discover a number of novel facts about the organization of the nervous system, inspiring the birth of the neuron doctrine. Ultimately, Ramón y Cajal improved the technique by using a method he termed "double impregnation". Ramón y Cajal's staining technique, still in use, is called Cajal's Stain.
Mechanism
The cells in nervous tissue are densely packed and little information on their structures and interconnections can be obtained if all the cells are stained. Furthermore, the thin filamentary extensions of neural cells, including the axon and the dendrites of neurons, are too slender and transparent to be seen with normal staining techniques. Golgi's method stains a limited number of cells at random in their entirety. The mechanism by which this happens is still largely unknown. Dendrites, as well as the cell soma, are clearly stained in brown and black and can be followed in their entire length, which allowed neuroanatomists to track connections between neurons and to make visible the complex networking structure of many parts of the brain and spinal cord.
Golgi's staining is achieved by impregnating aldehyde fixed nervous tissue with potassium dichromate and silver nitrate. Cells thus stained are filled by microcrystallization of silver chromate.
Technique
According to SynapseWeb, this is the recipe for Golgi's staining technique:
Immerse a block (approx. 10x5 mm) of formaldehyde-fixed (or paraformaldehyde- glutaraldehyde-perfused) brain tissue into a 2% aqueous solution of potass |
https://en.wikipedia.org/wiki/Allelopathy | Allelopathy is a biological phenomenon by which an organism produces one or more biochemicals that influence the germination, growth, survival, and reproduction of other organisms. These biochemicals are known as allelochemicals and can have beneficial (positive allelopathy) or detrimental (negative allelopathy) effects on the target organisms and the community. Allelopathy is often used narrowly to describe chemically-mediated competition between plants; however, it is sometimes defined more broadly as chemically-mediated competition between any type of organisms. Allelochemicals are a subset of secondary metabolites, which are not directly required for metabolism (i.e. growth, development and reproduction) of the allelopathic organism.
Allelopathic interactions are an important factor in determining species distribution and abundance within plant communities, and are also thought to be important in the success of many invasive plants. For specific examples, see black walnut (Juglans nigra), tree of heaven (Ailanthus altissima), black crowberry (Empetrum nigrum), spotted knapweed (Centaurea stoebe), garlic mustard (Alliaria petiolata), Casuarina/Allocasuarina spp., and nutsedge.
It can often be difficult in practice to distinguish allelopathy from resource competition. While the former is caused by the addition of a harmful chemical agent to the environment, the latter is caused by the removal of essential nutrients (or water). Often, both mechanisms can act simultaneously. Moreover, some allelochemicals may function by reducing nutrient availability. Further confounding the issue, the production of allelochemicals can itself be affected by environmental factors such as nutrient availability, temperature and pH. Today, most ecologists recognize the existence of allelopathy, however many particular cases remain controversial.
History
The term allelopathy from the Greek-derived compounds - () and - () (meaning "mutual harm" or "suffering"), was first used in 1937 |
https://en.wikipedia.org/wiki/Compare-and-swap | In computer science, compare-and-swap (CAS) is an atomic instruction used in multithreading to achieve synchronization. It compares the contents of a memory location with a given value and, only if they are the same, modifies the contents of that memory location to a new given value. This is done as a single atomic operation. The atomicity guarantees that the new value is calculated based on up-to-date information; if the value had been updated by another thread in the meantime, the write would fail. The result of the operation must indicate whether it performed the substitution; this can be done either with a simple boolean response (this variant is often called compare-and-set), or by returning the value read from the memory location (not the value written to it).
Overview
A compare-and-swap operation is an atomic version of the following pseudocode, where denotes access through a pointer:
function cas(p: pointer to int, old: int, new: int) is
if *p ≠ old
return false
*p ← new
return true
This operation is used to implement synchronization primitives like semaphores and mutexes, as well as more sophisticated lock-free and wait-free algorithms. Maurice Herlihy (1991) proved that CAS can implement more of these algorithms than atomic read, write, or fetch-and-add, and assuming a fairly large amount of memory, that it can implement all of them. CAS is equivalent to load-link/store-conditional, in the sense that a constant number of invocations of either primitive can be used to implement the other one in a wait-free manner.
Algorithms built around CAS typically read some key memory location and remember the old value. Based on that old value, they compute some new value. Then they try to swap in the new value using CAS, where the comparison checks for the location still being equal to the old value. If CAS indicates that the attempt has failed, it has to be repeated from the beginning: the location is re-read, a new value is re-compu |
https://en.wikipedia.org/wiki/Local%20Security%20Authority%20Subsystem%20Service | Local Security Authority Subsystem Service (LSASS) is a process in Microsoft Windows operating systems that is responsible for enforcing the security policy on the system. It verifies users logging on to a Windows computer or server, handles password changes, and creates access tokens. It also writes to the Windows Security Log.
Forcible termination of will result in the system losing access to any account, including NT AUTHORITY, prompting a restart of the machine.
Because is a crucial system file, its name is often faked by malware. The file used by Windows is located in the directory and the description of the file is Local Security Authority Process. If it is running from any other location, that is most likely a virus, spyware, trojan or worm. Due to the way some systems display fonts, malicious developers may name the file something like (capital "i" instead of a lowercase "L") in efforts to trick users into installing or executing a malicious file instead of the trusted system file. The Sasser worm spreads by exploiting a buffer overflow in the LSASS on Windows XP and Windows 2000 operating systems.
References
External links
Security Subsystem Architecture
LSA Authentication
MS identity management
Microsoft Windows security technology
Windows NT architecture
Access control software
Windows components |
https://en.wikipedia.org/wiki/Reinsurance | Reinsurance is insurance that an insurance company purchases from another insurance company to insulate itself (at least in part) from the risk of a major claims event. With reinsurance, the company passes on ("cedes") some part of its own insurance liabilities to the other insurance company. The company that purchases the reinsurance policy is referred to as the "ceding company" or "cedent". The company issuing the reinsurance policy is referred to as the "reinsurer". In the classic case, reinsurance allows insurance companies to remain solvent after major claims events, such as major disasters like hurricanes or wildfires. In addition to its basic role in risk management, reinsurance is sometimes used to reduce the ceding company's capital requirements, or for tax mitigation or other purposes.
The reinsurer may be either a specialist reinsurance company, which only undertakes reinsurance business, or another insurance company. Insurance companies that accept reinsurance refer to the business as "assumed reinsurance".
There are two basic methods of reinsurance:
Facultative Reinsurance, which is negotiated separately for each insurance policy that is reinsured. Facultative reinsurance is normally purchased by ceding companies for individual risks not covered, or insufficiently covered, by their reinsurance treaties, for amounts in excess of the monetary limits of their reinsurance treaties and for unusual risks. Underwriting expenses, and in particular personnel costs, are higher for such business because each risk is individually underwritten and administered. However, as they can separately evaluate each risk reinsured, the reinsurer's underwriter can price the contract more accurately to reflect the risks involved. Ultimately, a facultative certificate is issued by the reinsurance company to the ceding company reinsuring that one policy, and is used for high-value or hazardous risks.
Treaty Reinsurance means that the ceding company and the reinsurer negoti |
https://en.wikipedia.org/wiki/List%20of%20algorithm%20general%20topics | This is a list of algorithm general topics.
Analysis of algorithms
Ant colony algorithm
Approximation algorithm
Best and worst cases
Big O notation
Combinatorial search
Competitive analysis
Computability theory
Computational complexity theory
Embarrassingly parallel problem
Emergent algorithm
Evolutionary algorithm
Fast Fourier transform
Genetic algorithm
Graph exploration algorithm
Heuristic
Hill climbing
Implementation
Las Vegas algorithm
Lock-free and wait-free algorithms
Monte Carlo algorithm
Numerical analysis
Online algorithm
Polynomial time approximation scheme
Problem size
Pseudorandom number generator
Quantum algorithm
Random-restart hill climbing
Randomized algorithm
Running time
Sorting algorithm
Search algorithm
Stable algorithm (disambiguation)
Super-recursive algorithm
Tree search algorithm
See also
List of algorithms for specific algorithms
List of computability and complexity topics for more abstract theory
List of complexity classes, complexity class
List of data structures.
Mathematics-related lists |
https://en.wikipedia.org/wiki/Quantum%20algorithm | In quantum computing, a quantum algorithm is an algorithm which runs on a realistic model of quantum computation, the most commonly used model being the quantum circuit model of computation. A classical (or non-quantum) algorithm is a finite sequence of instructions, or a step-by-step procedure for solving a problem, where each step or instruction can be performed on a classical computer. Similarly, a quantum algorithm is a step-by-step procedure, where each of the steps can be performed on a quantum computer. Although all classical algorithms can also be performed on a quantum computer, the term quantum algorithm is usually used for those algorithms which seem inherently quantum, or use some essential feature of quantum computation such as quantum superposition or quantum entanglement.
Problems which are undecidable using classical computers remain undecidable using quantum computers. What makes quantum algorithms interesting is that they might be able to solve some problems faster than classical algorithms because the quantum superposition and quantum entanglement that quantum algorithms exploit probably cannot be efficiently simulated on classical computers (see Quantum supremacy).
The best-known algorithms are Shor's algorithm for factoring and Grover's algorithm for searching an unstructured database or an unordered list. Shor's algorithms runs much (almost exponentially) faster than the best-known classical algorithm for factoring, the general number field sieve. Grover's algorithm runs quadratically faster than the best possible classical algorithm for the same task, a linear search.
Overview
Quantum algorithms are usually described, in the commonly used circuit model of quantum computation, by a quantum circuit which acts on some input qubits and terminates with a measurement. A quantum circuit consists of simple quantum gates which act on at most a fixed number of qubits. The number of qubits has to be fixed because a changing number of qubits implies n |
https://en.wikipedia.org/wiki/Numerical%20Recipes | Numerical Recipes is the generic title of a series of books on algorithms and numerical analysis by William H. Press, Saul A. Teukolsky, William T. Vetterling and Brian P. Flannery. In various editions, the books have been in print since 1986. The most recent edition was published in 2007.
Overview
The Numerical Recipes books cover a range of topics that include both classical numerical analysis (interpolation, integration, linear algebra, differential equations, and so on), signal processing (Fourier methods, filtering), statistical treatment of data, and a few topics in machine learning (hidden Markov model, support vector machines). The writing style is accessible and has an informal tone. The emphasis is on understanding the underlying basics of techniques, not on the refinements that may, in practice, be needed to achieve optimal performance and reliability. Few results are proved with any degree of rigor, although the ideas behind proofs are often sketched, and references are given. Importantly, virtually all methods that are discussed are also implemented in a programming language, with the code printed in the book. Each version is keyed to a specific language.
According to the publisher, Cambridge University Press, the Numerical Recipes books are historically the all-time best-selling books on scientific programming methods. In recent years, Numerical Recipes books have been cited in the scientific literature more than 3000 times per year according to ISI Web of Knowledge (e.g., 3962 times in the year 2008). And as of the end of 2017, the book had over 44000 citations on Google Scholar.
History
The first publication was in 1986 with the title,”Numerical Recipes, The Art of Scientific Computing”, containing code in both Fortran and Pascal; an accompanying book, “Numerical Recipes Example Book (Pascal)” was first published in 1985. (A preface note in “Examples" mentions that the main book was also published in 1985, but the official note in that book s |
https://en.wikipedia.org/wiki/Coimage | In algebra, the coimage of a homomorphism
is the quotient
of the domain by the kernel.
The coimage is canonically isomorphic to the image by the first isomorphism theorem, when that theorem applies.
More generally, in category theory, the coimage of a morphism is the dual notion of the image of a morphism. If , then a coimage of (if it exists) is an epimorphism such that
there is a map with ,
for any epimorphism for which there is a map with , there is a unique map such that both and
See also
Quotient object
Cokernel
References
Abstract algebra
Isomorphism theorems
Category theory
pl:Twierdzenie o izomorfizmie#Pierwsze twierdzenie |
https://en.wikipedia.org/wiki/HEAnet | HEAnet is the national education and research network of Ireland.
HEAnet's e-infrastructure services support approximately 210,000 students and staff (third-level) in Ireland, and approximately 800,000 students and staff (first and second-level) relying on the HEAnet network. In total, the network supports approximately 1 million users.
Established in 1983 by a number of Irish universities, and supported by the Higher Education Authority, HEAnet provides e-infrastructure services to schools, colleges and universities within the Irish education system. Its network connects Irish universities, Institutes of technology in Ireland, the Irish Centre for High-End Computing (National Supercomputing Centre) and other higher education institutions (HEIs). It also provides internet services to primary and post-primary schools in Ireland and research organisations. Their clients also include various state-sponsored bodies, including hosting the online live conferencing service of the Oireachtas, the parliament of Ireland.
HEAnet also hosts a mirror service, which acts as a mirror for projects such as SourceForge, Debian, and Ubuntu.
In 2014, HEAnet hosted the TERENA Conference in Dublin. It was held between 19 and 22 May 2014 in Dublin.
In 2017, HEAnet announced additional investment in "100Gbps [services] to boost bandwidth accessed by [...] 216 academic locations around Ireland".
References
External links
HEAnet network map
Education in the Republic of Ireland
Internet in Ireland
Internet mirror services
National research and education networks |
https://en.wikipedia.org/wiki/Haboush%27s%20theorem | In mathematics Haboush's theorem, often still referred to as the Mumford conjecture, states that for any semisimple algebraic group G over a field K, and for any linear representation ρ of G on a K-vector space V, given v ≠ 0 in V that is fixed by the action of G, there is a G-invariant polynomial F on V, without constant term, such that
F(v) ≠ 0.
The polynomial can be taken to be homogeneous, in other words an element of a symmetric power of the dual of V, and if the characteristic is p>0 the degree of the polynomial can be taken to be a power of p.
When K has characteristic 0 this was well known; in fact Weyl's theorem on the complete reducibility of the representations of G implies that F can even be taken to be linear. Mumford's conjecture about the extension to prime characteristic p was proved by W. J. , about a decade after the problem had been posed by David Mumford, in the introduction to the first edition of his book Geometric Invariant Theory.
Applications
Haboush's theorem can be used to generalize results of geometric invariant theory from characteristic 0, where they were already known, to characteristic p>0. In particular Nagata's earlier results together with Haboush's theorem show that if a reductive group (over an algebraically closed field) acts on a finitely generated algebra then the fixed subalgebra is also finitely generated.
Haboush's theorem implies that if G is a reductive algebraic group acting regularly on an affine algebraic variety, then disjoint closed invariant sets X and Y can be separated by an invariant function f (this means that f is 0 on X and 1 on Y).
C.S. Seshadri (1977) extended Haboush's theorem to reductive groups over schemes.
It follows from the work of , Haboush, and Popov that the following conditions are equivalent for an affine algebraic group G over a field K:
G is reductive (its unipotent radical is trivial).
For any non-zero invariant vector in a rational representation of G, there is an invariant homogeneou |
https://en.wikipedia.org/wiki/Lament | A lament or lamentation is a passionate expression of grief, often in music, poetry, or song form. The grief is most often born of regret, or mourning. Laments can also be expressed in a verbal manner in which participants lament about something that they regret or someone that they have lost, and they are usually accompanied by wailing, moaning and/or crying. Laments constitute some of the oldest forms of writing, and examples exist across human cultures.
History
Many of the oldest and most lasting poems in human history have been laments. The Lament for Sumer and Ur dates back at least 4000 years to ancient Sumer, the world's first urban civilization. Laments are present in both the Iliad and the Odyssey, and laments continued to be sung in elegiacs accompanied by the aulos in classical and Hellenistic Greece. Elements of laments appear in Beowulf, in the Hindu Vedas, and in ancient Near Eastern religious texts. They are included in the Mesopotamian City Laments such as the Lament for Ur and the Jewish Tanakh, (which Christians refer to as the Old Testament).
In many oral traditions, both early and modern, the lament has been a genre usually performed by women: Batya Weinbaum made a case for the spontaneous lament of women chanters in the creation of the oral tradition that resulted in the Iliad The material of lament, the "sound of trauma" is as much an element in the Book of Job as in the genre of pastoral elegy, such as Shelley's "Adonais" or Matthew Arnold's "Thyrsis".
The Book of Lamentations or Lamentations of Jeremiah figures in the Old Testament. The Lamentation of Christ (under many closely variant terms) is a common subject from the Life of Christ in art, showing Jesus' dead body being mourned after the Crucifixion. Jesus himself lamented over the prospective fall of Jerusalem as he and his disciples entered the city ahead of his passion.
A lament in the Book of Lamentations or in the Psalms, in particular in the Lament/Complaint Psalms of the Tanak |
https://en.wikipedia.org/wiki/American%20Society%20of%20Mechanical%20Engineers | The American Society of Mechanical Engineers (ASME) is an American professional association that, in its own words, "promotes the art, science, and practice of multidisciplinary engineering and allied sciences around the globe" via "continuing education, training and professional development, codes and standards, research, conferences and publications, government relations, and other forms of outreach." ASME is thus an engineering society, a standards organization, a research and development organization, an advocacy organization, a provider of training and education, and a nonprofit organization. Founded as an engineering society focused on mechanical engineering in North America, ASME is today multidisciplinary and global.
ASME has over 85,000 members in more than 135 countries worldwide.
ASME was founded in 1880 by Alexander Lyman Holley, Henry Rossiter Worthington, John Edison Sweet and Matthias N. Forney in response to numerous steam boiler pressure vessel failures. Known for setting codes and standards for mechanical devices, ASME conducts one of the world's largest technical publishing operations. It holds numerous technical conferences and hundreds of professional development courses each year and sponsors numerous outreach and educational programs. Georgia Tech president and women engineer supporter Blake R Van Leer was an executive member. Kate Gleason and Lydia Weld were the first two women members.
ASME codes and standards
ASME is one of the oldest standards-developing organizations in America. It produces approximately 600 codes and standards covering many technical areas, such as fasteners, plumbing fixtures, elevators, pipelines, and power plant systems and components. ASME's standards are developed by committees of subject matter experts using an open, consensus-based process. Many ASME standards are cited by government agencies as tools to meet their regulatory objectives. ASME standards are therefore voluntary, unless the standards have been |
https://en.wikipedia.org/wiki/Fluorescence%20recovery%20after%20photobleaching | Fluorescence recovery after photobleaching (FRAP) is a method for determining the kinetics of diffusion through tissue or cells. It is capable of quantifying the two-dimensional lateral diffusion of a molecularly thin film containing fluorescently labeled probes, or to examine single cells. This technique is very useful in biological studies of cell membrane diffusion and protein binding. In addition, surface deposition of a fluorescing phospholipid bilayer (or monolayer) allows the characterization of hydrophilic (or hydrophobic) surfaces in terms of surface structure and free energy.
Similar, though less well known, techniques have been developed to investigate the 3-dimensional diffusion and binding of molecules inside the cell; they are also referred to as FRAP.
Experimental setup
The basic apparatus comprises an optical microscope, a light source and some fluorescent probe. Fluorescent emission is contingent upon absorption of a specific optical wavelength or color which restricts the choice of lamps. Most commonly, a broad spectrum mercury or xenon source is used in conjunction with a color filter. The technique begins by saving a background image of the sample before photobleaching. Next, the light source is focused onto a small patch of the viewable area either by switching to a higher magnification microscope objective or with laser light of the appropriate wavelength. The fluorophores in this region receive high intensity illumination which causes their fluorescence lifetime to quickly elapse (limited to roughly 105 photons before extinction). Now the image in the microscope is that of a uniformly fluorescent field with a noticeable dark spot. As Brownian motion proceeds, the still-fluorescing probes will diffuse throughout the sample and replace the non-fluorescent probes in the bleached region. This diffusion proceeds in an ordered fashion, analytically determinable from the diffusion equation. Assuming a Gaussian profile for the bleaching beam, the d |
https://en.wikipedia.org/wiki/Disk%20cloning | Disk cloning is the process of duplicating all data on a digital storage drive, such as a hard disk or solid state drive, using hardware or software techniques. Unlike file copying, disk cloning also duplicates the filesystems, partitions, drive meta data and slack space on the drive. Common reasons for cloning a drive include; data backup and recovery; duplicating a computer's configuration for mass deployment and for preserving data for digital forensics purposes. Drive cloning can be used in conjunction with drive imaging where the cloned data is saved to one or more files on another drive rather than copied directly to another drive.
Background
Disk cloning occurs by copying the contents of a drive called the source drive. While called "disk cloning", any type of storage medium that connects to the computer via USB, NVMe or SATA can be cloned. A small amount of data is read and then held in the computer's memory. The data is then either written directly to another (destination) drive or to a disk image.
Typically, the destination drive is connected to a computer (Fig. 1). Once connected, a disk cloner is used to perform the clone itself. A hardware-based drive cloner can be used which does not require a computer. However, software cloners tend to allow for greater flexibility because they can exclude unwanted data from being duplicated reducing cloning time. For example, the filesystem and partitions can be resized by the software allowing data to be cloned to a drive equal to or greater than the total used space. Most hardware-based cloners typically require for the destination drive to be the same size as the source drive even if only a fraction of the space is used. Some hardware cloners can clone only the used space but tend to be much more expensive.
Applications
Deployment
A common use of disk cloning is for deployment. For example, a group of computers with similar hardware can be set up much quicker by cloning the configuration. In educational i |
https://en.wikipedia.org/wiki/Analytical%20hierarchy | In mathematical logic and descriptive set theory, the analytical hierarchy is an extension of the arithmetical hierarchy. The analytical hierarchy of formulas includes formulas in the language of second-order arithmetic, which can have quantifiers over both the set of natural numbers, , and over functions from to . The analytical hierarchy of sets classifies sets by the formulas that can be used to define them; it is the lightface version of the projective hierarchy.
The analytical hierarchy of formulas
The notation
indicates the class of formulas in the language of second-order arithmetic with number quantifiers but no set quantifiers. This language does not contain set parameters. The Greek letters here are lightface symbols, which indicate this choice of language. Each corresponding boldface symbol denotes the corresponding class of formulas in the extended language with a parameter for each real; see projective hierarchy for details.
A formula in the language of second-order arithmetic is defined to be if it is logically equivalent to a formula of the form where is . A formula is defined to be if it is logically equivalent to a formula of the form where is . This inductive definition defines the classes and for every natural number .
Kuratowski and Tarski showed in 1931 that every formula in the language of second-order arithmetic has a prenex normal form, and therefore or for some . Because meaningless quantifiers can be added to any formula, once a formula is given the classification or for some it will be given the classifications and for all greater than .
The analytical hierarchy of sets of natural numbers
A set of natural numbers is assigned the classification if it is definable by a formula. The set is assigned the classification if it is definable by a formula. If the set is both and then it is given the additional classification .
The sets are called hyperarithmetical. An alternate classification of these sets by way of i |
https://en.wikipedia.org/wiki/Wheel%20theory | A wheel is a type of algebra (in the sense of universal algebra) where division is always defined. In particular, division by zero is meaningful. The real numbers can be extended to a wheel, as can any commutative ring.
The term wheel is inspired by the topological picture of the real projective line together with an extra point ⊥ (bottom element) such as .
A wheel can be regarded as the equivalent of a commutative ring (and semiring) where addition and multiplication are not a group but respectively a commutative monoid and a commutative monoid with involution.
Definition
A wheel is an algebraic structure , in which
is a set,
and are elements of that set,
and are binary operations,
is a unary operation,
and satisfying the following properties:
and are each commutative and associative, and have and as their respective identities.
( is an involution)
( is multiplicative)
Algebra of wheels
Wheels replace the usual division as a binary operation with multiplication, with a unary operation applied to one argument similar (but not identical) to the multiplicative inverse , such that becomes shorthand for , but neither nor in general, and modifies the rules of algebra such that
in the general case
in the general case, as is not the same as the multiplicative inverse of .
Other identities that may be derived are
where the negation is defined by and if there is an element such that (thus in the general case ).
However, for values of satisfying and , we get the usual
If negation can be defined as below then the subset is a commutative ring, and every commutative ring is such a subset of a wheel. If is an invertible element of the commutative ring then . Thus, whenever makes sense, it is equal to , but the latter is always defined, even when .
Examples
Wheel of fractions
Let be a commutative ring, and let be a multiplicative submonoid of . Define the congruence relation on via
means that there exist such th |
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