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https://en.wikipedia.org/wiki/Ternary%20computer | A ternary computer, also called trinary computer, is one that uses ternary logic (i.e., base 3) instead of the more common binary system (i.e., base 2) in its calculations. This means it uses trits (instead of bits, as most computers do).
Types of states
Ternary computing deals with three discrete states, but the ternary digits themselves can be defined differently:
Ternary quantum computers use qutrits rather than trits. A qutrit is a quantum state that is a complex unit vector in three dimensions, which can be written as in the bra-ket notation. The labels given to the basis vectors () can be replaced with other labels, for example those given above.
History
One early calculating machine, built entirely from wood by Thomas Fowler in 1840, operated in balanced ternary. The first modern, electronic ternary computer, Setun, was built in 1958 in the Soviet Union at the Moscow State University by Nikolay Brusentsov, and it had notable advantages over the binary computers that eventually replaced it, such as lower electricity consumption and lower production cost. In 1970 Brusentsov built an enhanced version of the computer, which he called Setun-70. In the United States, the ternary computing emulator Ternac working on a binary machine was developed in 1973.
The ternary computer QTC-1 was developed in Canada.
Balanced ternary
Ternary computing is commonly implemented in terms of balanced ternary, which uses the three digits −1, 0, and +1. The negative value of any balanced ternary digit can be obtained by replacing every + with a − and vice versa. It is easy to subtract a number by inverting the + and − digits and then using normal addition. Balanced ternary can express negative values as easily as positive ones, without the need for a leading negative sign as with unbalanced numbers. These advantages make some calculations more efficient in ternary than binary. Considering that digit signs are mandatory, and nonzero digits are magnitude 1 only, notation th |
https://en.wikipedia.org/wiki/Web%20content%20development | Web content development is the process of researching, writing, gathering, organizing, and editing information for publication on websites. Website content may consist of prose, graphics, pictures, recordings, movies, or other digital assets that could be distributed by a hypertext transfer protocol server, and viewed by a web browser.
Content developers and web developers
When the World Wide Web began, web developers either developed online content themselves, or modified existing documents and coded them into hypertext markup language (HTML). In time, the field of website development came to encompass many technologies, so it became difficult for website developers to maintain so many different skills. Content developers are specialized website developers who have content generation skills such as graphic design, multimedia development, professional writing, and documentation. They can integrate content into new or existing websites without using information technology skills such as script language programming and database programming.
Content developers or technical content developers can also be technical writers who produce technical documentation that helps people understand and use a product or service. This documentation includes online help, manuals, white papers, design specifications, developer guides, deployment guides, release notes, etc.
Search engine optimization
Content developers may also be search engine optimization specialists, or internet marketing professionals. High quality, unique content is what search engines are looking for. Content development specialists, therefore, have a very important role to play in the search engine optimization process. One issue currently plaguing the world of web content development is keyword-stuffed content which are prepared solely for the purpose of manipulating search engine rankings. The effect is that content is written to appeal to search engine (algorithms) rather than human readers. Search engine |
https://en.wikipedia.org/wiki/Exoelectron%20emission | In atomic physics, exoelectron emission (EE) is a weak electron emission, appearing only from pretreated (irradiated, deformed etc.) objects. The pretreatment ("excitation") turns the objects into an unequilibrial state. EE accompanies the relaxation of these unequilibria. The relaxation can be stimulated e.g. by slight heating or longwave illumination, not causing emission from untreated samples. Accordingly, thermo- and photostimulated EE (TSEE, PSEE) are distinguished. Thus, EE is an electron emission analogue of such optical phenomena as phosphorescence, thermo- and photostimulated luminescence. |
https://en.wikipedia.org/wiki/Tea%20seed%20oil | Tea seed oil (also known as camellia oil, camellia seed oil, teanut oil) is an edible plant oil. It is obtained from the seeds of Camellia oleifera.
Camellia sasanqua is also given as a source of 'tea seed oil.
Description
The genus Camellia includes several commercially important species - Camellia oleifera is grown mainly in China for vegetable oil. The oil is known as 'camellia oil', 'tea seed oil', or 'camellia seed oil'. As of 2016 of oleifera forest centered on the Yangtze river basin in Hunan, Jiangxi, and Guangxi produces 0.26 million tons of oil.
Wild Camellia oleifera contains ~47% oil, whilst cultivated varieties have shown oil content from 42 to 53%. Oil analysis of cultivated varieties showed : ~76-82% oleic acid; 5-11% linoleic acid; 7.5-10% palmitic acid; 1.5-3% stearic acid - the ratios are similar to that found in wild oleifera. The composition is similar to that of Olive oil. Another analysis of several cultivars found : 82-84% unsaturated acids of which 68-77% oleic acid; and 7-14% polyunsaturated acids.
Uses
With its high smoke point of , tea seed oil is the main cooking oil in some of the southern provinces of People's Republic of China, such as Hunan, especially in mountainous regions; roughly one-seventh of the country's population.
The oil has also been used in Chinese traditional medicine - here it has been used as a dietary supplement for the digestive system, as well as to manage cholesterol, as well as strengthen the immune system. It was also used topically as baby lotion and for burn injuries.
Tea seed oil is commonly used to protect carbon steel cooking knives from rust.
Cautions
Tea seed oil should not be mistaken for tea tree oil (melaleuca oil), an inedible essential oil extracted from the leaves of the paperbark, Melaleuca alternifolia, which is used for medicinal purposes.
See also
Camellia japonica, source of an oil known as Tsubaki oil. Mainly used as cooking oil and to hold a hairstyle.
Camellia sinensis, for tea p |
https://en.wikipedia.org/wiki/DCE%20Distributed%20File%20System | The DCE Distributed File System (DCE/DFS) is the remote file access protocol used with the Distributed Computing Environment. It was a variant of Andrew File System (AFS), based on the AFS Version 3.0 protocol that was developed commercially by Transarc Corporation. AFS Version 3.0 was in turn based on the AFS Version 2.0 protocol (also used by the Coda disconnected file system) originally developed at Carnegie Mellon University.
DCE/DFS consisted of multiple cooperative components that provided a network file system with strong file system semantics, attempting to mimic the behavior of POSIX local file systems while taking advantage of performance optimizations when possible. A DCE/DFS client system utilized a locally managed cache that would contain copies (or regions) of the original file. The client system would coordinate with a server system where the original copy of the file was stored to ensure that multiple clients accessing the same file would re-fetch a cached copy of the file data when the original file had changed.
The advantage of this approach is that it provided very good performance even over slow network connections because most of the file access was actually done to the local cached regions of the file. If the server failed, the client could continue making changes to the file locally, storing it back to the server when it became available again.
DCE/DFS also divorced the concept of logical units of management (Filesets) from the underlying volume on which the fileset was stored. In doing this it allowed administrative control of the location for the fileset in a manner that was transparent to the end user. To support this and other advanced DCE/DFS features, a local journaling file system (DCE/LFS also known as Episode) was developed to provide the full range of support options.
IBM has not maintained it since 2005: https://web.archive.org/web/20071009171709/http://www-306.ibm.com/software/stormgmt/dfs/
IBM was working on a replacement |
https://en.wikipedia.org/wiki/Ternary%20search%20tree | In computer science, a ternary search tree is a type of trie (sometimes called a prefix tree) where nodes are arranged in a manner similar to a binary search tree, but with up to three children rather than the binary tree's limit of two. Like other prefix trees, a ternary search tree can be used as an associative map structure with the ability for incremental string search. However, ternary search trees are more space efficient compared to standard prefix trees, at the cost of speed. Common applications for ternary search trees include spell-checking and auto-completion.
Description
Each node of a ternary search tree stores a single character, an object (or a pointer to an object depending on implementation), and pointers to its three children conventionally named equal kid, lo kid and hi kid, which can also be referred respectively as middle (child), lower (child) and higher (child). A node may also have a pointer to its parent node as well as an indicator as to whether or not the node marks the end of a word. The lo kid pointer must point to a node whose character value is less than the current node. The hi kid pointer must point to a node whose character is greater than the current node. The equal kid points to the next character in the word.
The figure below shows a ternary search tree with the strings "cute","cup","at","as","he","us" and "i":
c
/ | \
a u h
| | | \
t t e u
/ / | / |
s p e i s
As with other trie data structures, each node in a ternary search tree represents a prefix of the stored strings. All strings in the middle subtree of a node start with that prefix.
Operations
Insertion
Inserting a value into a ternary search can be defined recursively or iteratively much as lookups are defined. This recursive method is continually called on nodes of the tree given a key which gets progressively shorter by pruning characters off the front of the key. If this method reaches a node tha |
https://en.wikipedia.org/wiki/Late%20bloomer | A late bloomer is a person whose talents or capabilities are not visible to others until later than usual. The term is used metaphorically to describe a child or adolescent who develops slower than others in their age group, but eventually catches up and in some cases overtakes their peers, or an adult whose talent or genius in a particular field only appears later in life than is normal – in some cases only in old age.
Children
There are many theories of the way in which children develop, proposed by authorities such as Urie Bronfenbrenner, Jerome Bruner, Erik Erikson, Jerome Kagan, Lawrence Kohlberg, Jean Piaget, and Lev Vygotsky. Although they disagree about how stages of development should be defined, and about the primary influences on development, they agree that a child's development can be measured as a predictable series of advances in physical, intellectual and social skills which almost always occur in the same sequence, although the rate may vary from one child to another.
When a child falls behind their peers at some stage of development, their teacher may perceive that the child is "backward". There is strong evidence that this perception may become self-fulfilling: although the child catches up, the teacher may continue to rate their performance poorly, imposing a long-term handicap. Thomas Edison's mind often wandered and his teacher was overheard calling him "addled." This ended Edison's three months of official schooling. His mother then home schooled him. Edison may have had some form of Attention-deficit hyperactivity disorder (ADHD), which the American Psychiatric Institute says affects about 3 – 5% of children.
A notable example of a child who overcame early developmental problems is Albert Einstein, who suffered from speech difficulties as a young child. Other late-talking children who became highly-successful engineers, mathematicians, and scientists include the physicists Richard Feynman and Edward Teller. Neuroscientist Steven Pinker po |
https://en.wikipedia.org/wiki/TRAIL | In the field of cell biology, TNF-related apoptosis-inducing ligand (TRAIL), is a protein functioning as a ligand that induces the process of cell death called apoptosis.
TRAIL is a cytokine that is produced and secreted by most normal tissue cells. It causes apoptosis primarily in tumor cells, by binding to certain death receptors. TRAIL and its receptors have been used as the targets of several anti-cancer therapeutics since the mid-1990s, such as Mapatumumab. However, as of 2013, these have not shown significant survival benefit. TRAIL has also been implicated as a pathogenic or protective factor in various pulmonary diseases, particularly pulmonary arterial hypertension.
TRAIL has also been designated CD253 (cluster of differentiation 253) and TNFSF10 (tumor necrosis factor (ligand) superfamily, member 10).
Gene
In humans, the gene that encodes TRAIL is located at chromosome 3q26, which is not close to other TNF family members. The genomic structure of the TRAIL gene spans approximately 20 kb and is composed of five exonic segments 222, 138, 42, 106, and 1245 nucleotides and four introns of approximately 8.2, 3.2, 2.3 and 2.3 kb.
The TRAIL gene lacks TATA and CAAT boxes and the promoter region contains putative response elements for transcription factors GATA, AP-1, C/EBP, SP-1, OCT-1, AP3, PEA3, CF-1, and ISRE.
The TRAIL gene as a drug target
TIC10 (which causes expression of TRAIL) was investigated in mice with various tumour types.
Small molecule ONC201 causes expression of TRAIL which kills some cancer cells.
Structure
TRAIL shows homology to other members of the tumor necrosis factor superfamily. It is composed of 281 amino acids and has characteristics of a type II transmembrane protein. The N-terminal cytoplasmic domain is not conserved across family members, however, the C-terminal extracellular domain is conserved and can be proteolytically cleaved from the cell surface. TRAIL forms a homotrimer that binds three receptor molecules.
Function |
https://en.wikipedia.org/wiki/Quantization%20%28music%29 | In digital music processing technology, quantization is the studio-software process of transforming performed musical notes, which may have some imprecision due to expressive performance, to an underlying musical representation that eliminates the imprecision. The process results in notes being set on beats and on exact fractions of beats.
The purpose of quantization in music processing is to provide a more beat-accurate timing of sounds. Quantization is frequently applied to a record of MIDI notes created by the use of a musical keyboard or drum machine. Additionally, the phrase "pitch quantization" can refer to pitch correction used in audio production, such as using Auto-Tune.
Description
A frequent application of quantization in this context lies within MIDI application software or hardware. MIDI sequencers typically include quantization in their manifest of edit commands. In this case, the dimensions of this timing grid are set beforehand. When one instructs the music application to quantize a certain group of MIDI notes in a song, the program moves each note to the closest point on the timing grid. Quantization in MIDI is usually applied to Note On messages and sometimes Note Off messages; some digital audio workstations shift the entire note by moving both messages together. Sometimes quantization is applied in terms of a percentage, to partially align the notes to a certain beat. Using a percentage of quantization allows for the subtle preservation of some natural human timing nuances.
The most difficult problem in quantization is determining which rhythmic fluctuations are imprecise or expressive (and should be removed by the quantization process) and which should be represented in the output score. For instance, a simple children's song should probably have very coarse quantization, resulting in few different notes in output. On the other hand, quantizing a performance of a piano piece by Arnold Schoenberg, for instance, should result in many smaller no |
https://en.wikipedia.org/wiki/Situation%20awareness | Situational awareness or situation awareness (SA) is the understanding of an environment, its elements, and how it changes with respect to time or other factors. Situational awareness is important for effective decision making in many environments. It is formally defined as:
An alternative definition is that situation awareness is adaptive, externally-directed consciousness that has as its products knowledge about a dynamic task environment and directed action within that environment.
Situation awareness has been recognized as a critical foundation for successful decision-making across a broad range of situations, many of which involve the protection of human life and property, including law enforcement, aviation, air traffic control, ship navigation, health care, emergency response, military command and control operations, transmission system operators, self defense, and offshore oil and nuclear power plant management.
Inadequate situation awareness has been identified as one of the primary causal factors in accidents attributed to human error. According to Endsley’s situation awareness theory, when someone meets a dangerous situation, he needs an appropriate and a precise decision-making process which include pattern recognition and matching, formation of sophisticated schemata and archetypal knowledge that aids correct decision making.
The formal definition of SA is often described as three ascending levels:
Perception of the elements in the environment,
Comprehension or understanding of the situation, and
Projection of future status.
People with the highest levels of SA have not only perceived the relevant information for their goals and decisions, but are also able to integrate that information to understand its meaning or significance, and are able project likely or possible future scenarios. These higher levels of SA are critical for proactive decision making in demanding environments.
Three facets of SA have been the focus in research: SA sta |
https://en.wikipedia.org/wiki/Qinpu | Qinpu () are tablature score collections for the guqin, a Chinese musical instrument.
Description
Qinpu are collections of tablatures of music for the guqin. In the past, music was passed on from teacher to student. Only recently has tablature been written down, often to preserve music or as a reference book. Tablature comes in form of individual pieces and collections. Collections often have explanations for fingering, background information, musical analyses, and other additional information attached to them.
Different types of qinpu
There are several different types of qinpu one can obtain.
Original editions are qinpu printed at the original time of publication, or re-issues during the past. These are mostly kept in libraries and private collections. Since they are original, they tend to be fragile.
Photographic reprints is basically a scan of the original qinpu and reduced size reprint in modern binding. The most famous is the Qinqu Jicheng.
Lithographic facsimiles are becoming more popular. The original qinpu is scanned, then it is lithographically printed on xuan paper. They are bound in traditional Chinese book binding method.
Modern reset editions appeared after 2005. These have modern typographic elements and are often reset using more recent editions or handcopies of original qinpu.
See also
Qin notation |
https://en.wikipedia.org/wiki/Bosonization | In theoretical condensed matter physics and quantum field theory, bosonization is a mathematical procedure by which a system of interacting fermions in (1+1) dimensions can be transformed to a system of massless, non-interacting bosons.
The method of bosonization was conceived independently by particle physicists Sidney Coleman and Stanley Mandelstam; and condensed matter physicists Daniel C. Mattis and Alan Luther in 1975.
In particle physics, however, the boson is interacting, cf, the Sine-Gordon model, and notably through topological interactions, cf. Wess–Zumino–Witten model.
The basic physical idea behind bosonization is that particle-hole excitations are bosonic in character. However, it was shown by Tomonaga in 1950 that this principle is only valid in one-dimensional systems. Bosonization is an effective field theory that focuses on low-energy excitations.
Mathematical descriptions
A pair of chiral fermions , one being the conjugate variable of the other, can be described in terms of a chiral boson
where the currents of these two models are related by
where composite operators must be defined by a regularization and a subsequent renormalization.
Examples
In particle physics
The standard example in particle physics, for a Dirac field in (1+1) dimensions, is the equivalence between the massive Thirring model (MTM) and the quantum Sine-Gordon model. Sidney Coleman showed the Thirring model is S-dual to the sine-Gordon model. The fundamental fermions of the Thirring model correspond to the solitons (bosons) of the sine-Gordon model.
In condensed matter
The Luttinger liquid model, proposed by Tomonaga and reformulated by J.M. Luttinger, describes electrons in one-dimensional electrical conductors under second-order interactions. and Elliot H. Lieb proved in 1965 that electrons could be modeled as bosonic interactions. The response of the electron density to an external perturbation can be treated as plasmonic waves. This model predicts the emerge |
https://en.wikipedia.org/wiki/Supersplit%20supersymmetry | Supersplit supersymmetry was conceived as an April Fool's Day joke in 2005 by a group of young theoretical high energy physicists. It was meant as a parody of split supersymmetry.
The model proposed particles (beyond those of the Standard Model) which are decoupled, leaving no trace at low energies, therefore leaving just the Standard Model. The paper argued that the 30% accuracy of gauge coupling unification in the Standard Model is on par with the 1% accuracy in the MSSM or Split Supersymmetry. It also used the well-known possibility that a Peccei-Quinn axion could be the dark matter of the universe.
As a serious scientific theory, it leads to no new predictions beyond the Standard Model, and is therefore unverifiable. As a social commentary, it demonstrates the uneasiness in the high energy physics community about the direction some model building is heading.
Despite the original intent as a ridiculous proposal, the original paper has been cited by few theoretical physicists.
Very recently, a paper by Giudice and Strumia has presented the same idea under the name 'high scale supersymmetry'. |
https://en.wikipedia.org/wiki/Helicity%20%28particle%20physics%29 | In physics, helicity is the projection of the spin onto the direction of momentum.
Overview
The angular momentum J is the sum of an orbital angular momentum L and a spin S. The relationship between orbital angular momentum L, the position operator r and the linear momentum (orbit part) p is
so L's component in the direction of p is zero. Thus, helicity is just the projection of the spin onto the direction of linear momentum. The helicity of a particle is positive (" right-handed") if the direction of its spin is the same as the direction of its motion and negative ("left-handed") if opposite.
Helicity is conserved. That is, the helicity commutes with the Hamiltonian, and thus, in the absence of external forces, is time-invariant. It is also rotationally invariant, in that a rotation applied to the system leaves the helicity unchanged. Helicity, however, is not Lorentz invariant; under the action of a Lorentz boost, the helicity may change sign. Consider, for example, a baseball, pitched as a gyroball, so that its spin axis is aligned with the direction of the pitch. It will have one helicity with respect to the point of view of the players on the field, but would appear to have a flipped helicity in any frame moving faster than the ball.
Comparison with chirality
In this sense, helicity can be contrasted
to chirality, which is Lorentz invariant, but is not a constant of motion for massive particles. For massless particles, the two coincide: The helicity is equal to the chirality, both are Lorentz invariant, and both are constants of motion.
In quantum mechanics, angular momentum is quantized, and thus helicity is quantized as well. Because the eigenvalues of spin with respect to an axis have discrete values, the eigenvalues of helicity are also discrete. For a massive particle of spin , the eigenvalues of helicity are , , , ..., −.
For massless particles, not all of spin eigenvalues correspond to physically meaningful degrees of freedom: For example, the pho |
https://en.wikipedia.org/wiki/Boustrophedon%20transform | In mathematics, the boustrophedon transform is a procedure which maps one sequence to another. The transformed sequence is computed by an "addition" operation, implemented as if filling a triangular array in a boustrophedon (zigzag- or serpentine-like) manner—as opposed to a "Raster Scan" sawtooth-like manner.
Definition
The boustrophedon transform is a numerical, sequence-generating transformation, which is determined by an "addition" operation.
Generally speaking, given a sequence: , the boustrophedon transform yields another sequence: , where is likely defined equivalent to . The entirety of the transformation itself can be visualized (or imagined) as being constructed by filling-out the triangle as shown in Figure 1.
Boustrophedon Triangle
To fill-out the numerical Isosceles triangle (Figure 1), you start with the input sequence, , and place one value (from the input sequence) per row, using the boustrophedon scan (zigzag- or serpentine-like) approach.
The top vertex of the triangle will be the input value , equivalent to output value , and we number this top row as row 0.
The subsequent rows (going down to the base of the triangle) are numbered consecutively (from 0) as integers—let denote the number of the row currently being filled. These rows are constructed according to the row number () as follows:
For all rows, numbered , there will be exactly values in the row.
If is odd, then put the value on the right-hand end of the row.
Fill-out the interior of this row from right-to-left, where each value (index: ) is the result of "addition" between the value to right (index: ) and the value to the upper right (index: ).
The output value will be on the left-hand end of an odd row (where is odd).
If is even, then put the input value on the left-hand end of the row.
Fill-out the interior of this row from left-to-right, where each value (index: ) is the result of "addition" between the value to its left (index: ) and the value to its upper left |
https://en.wikipedia.org/wiki/786%20%28number%29 | 786 (seven hundred [and] eighty-six) is the natural number following 785 and preceding 787.
In mathematics
786 is:
a sphenic number.
a Harshad number in bases 4, 5, 7, 14 and 16.
the aliquot sum of 510.
part of the 321329-aliquot tree. The complete aliquot sequence starting at 498 is: 498, 510, 786, 798, 1122, 1470, 2634, 2646, 4194, 4932, 7626, 8502, 9978, 9990, 17370, 28026, 35136, 67226, 33616, 37808, 40312, 35288, 37072, 45264, 79728, 146448, 281166, 281178, 363942, 424638, 526338, 722961, 321329, 1, 0
50 can be partitioned into powers of two in 786 different ways .
786 might be the largest n for which the value of the central binomial coefficient is not divisible by an odd prime squared. If there is a larger such number, it would have to be at least 157450 (see ).
Area code
786 is a United States telephone area code in Miami-Dade County. As an overlay area code, it shares the same geographic numbering plan area with other codes for a larger pool of telephone numbers.
In other fields
80786 - 7th generation x86 like Athlon and Intel Pentium 4
The USSD code 786, typically dialed as ##786# or *#786#, opens the RTN dialog on some cell phones. "RTN" is 786 when dialed on an E.161 telephone pad.
In the New General Catalogue, NGC786 is a magnitude 13.5 spiral galaxy in the constellation Aries. Additionally, 786 Bredichina is an asteroid.
In juggling, 786 as fourhanded Siteswap is also known as French threecount.
In Islam, 786 is often used to represent the Arabic phrase Bismillah.
In films
The number is often featured in films, mostly due to its auspiciousness in Islamic culture.
Vijay Verma's (Amitabh Bachchan) coolie number in the 1975 Hindi film Deewaar.
Raja's (Rajnikanth) coolie number in the 1981 Tamil film Thee, a remake of Deewaar.
Iqbal Khan's (Amitabh Bachchan) coolie number in the 1983 Hindi film Coolie.
Bachchan has indicated that he believes the number is auspicious, as he survived a serious injury while wearing this number during the shoot |
https://en.wikipedia.org/wiki/Kretschmann%20scalar | In the theory of Lorentzian manifolds, particularly in the context of applications to general relativity, the Kretschmann scalar is a quadratic scalar invariant. It was introduced by Erich Kretschmann.
Definition
The Kretschmann invariant is
where is the Riemann curvature tensor (in this equation the Einstein summation convention was used, and it will be used throughout the article). Because it is a sum of squares of tensor components, this is a quadratic invariant.
For the use of a computer algebra system a more detailed writing is meaningful:
Examples
For a Schwarzschild black hole of mass , the Kretschmann scalar is
where is the gravitational constant.
For a general FRW spacetime with metric
the Kretschmann scalar is
Relation to other invariants
Another possible invariant (which has been employed for example in writing the gravitational term of the Lagrangian for some higher-order gravity theories) is
where is the Weyl tensor, the conformal curvature tensor which is also the completely traceless part of the Riemann tensor. In dimensions this is related to the Kretschmann invariant by
where is the Ricci curvature tensor and is the Ricci scalar curvature (obtained by taking successive traces of the Riemann tensor). The Ricci tensor vanishes in vacuum spacetimes (such as the Schwarzschild solution mentioned above), and hence there the Riemann tensor and the Weyl tensor coincide, as do their invariants.
Gauge theory invariants
The Kretschmann scalar and the Chern-Pontryagin scalar
where is the left dual of the Riemann tensor, are mathematically analogous (to some extent, physically analogous) to the familiar invariants of the electromagnetic field tensor
Generalising from the gauge theory of electromagnetism to general non-abelian gauge theory, the first of these invariants is
,
an expression proportional to the Yang–Mills Lagrangian. Here is the curvature of a covariant derivative, and is a trace form. The Kretschmann scalar arises from t |
https://en.wikipedia.org/wiki/DejaGnu | DejaGnu is a software framework for testing other programs. It has a main script called runtest that goes through a directory looking at configuration files and then runs some tests with given criteria. The purpose of the DejaGnu package is to provide a single front end for all tests. It is a part of the GNU Project and is licensed under the GPL. It is based on Expect, which is in turn based on Tcl. The current maintainers are Rob Savoye and Ben Elliston.
Testing
DejaGnu has a very strong history in testing due to its Tcl base. Tcl is used extensively by companies such as Oracle and Sybase to test their products. DejaGnu allows this work to be much more structured.
The tests can be grouped according to the tool they are testing. The test is run by merely calling in the root project directory.
runtest --tool program_to_test
This will look in the directory for any folders starting with and will run all .exp files in that folder.
Embedded design
One field for which DejaGnu is particularly well suited is that of embedded system design. It allows for testing to be done remotely on development boards; separate initialization files can be created for each operating system and board. This mainly focuses on embedded targets and remote hosts. DejaGnu is thus popular with many GNU projects, at universities, and for private companies.
Files
Essential Files
Each directory in testsuite should contain tests for a specific tool. In this example, the tool being tested is the Apache webserver.
This will be the file containing tests, which in this fictional case might change configuration options, and then connect to the network and check to make sure the changes have taken effect.
This file will be run as a tool init file for the tool called toolname.
Other Files
This file is a directory specific configuration file for . Options can be placed in this file rather than retyped on each invocation; these options can include any variable passed as a command line arg |
https://en.wikipedia.org/wiki/Methylglyoxal | Methylglyoxal (MGO) is the organic compound with the formula CH3C(O)CHO. It is a reduced derivative of pyruvic acid. It is a reactive compound that is implicated in the biology of diabetes. Methylglyoxal is produced industrially by degradation of carbohydrates using overexpressed methylglyoxal synthase.
Chemical structure
Gaseous methylglyoxal has two carbonyl groups, an aldehyde and a ketone. In the presence of water, it exists as hydrates and oligomers. The formation of these hydrates is indicative of the high reactivity of MGO, which is relevant to its biological behavior.
Biochemistry
Biosynthesis and biodegradation
In organisms, methylglyoxal is formed as a side-product of several metabolic pathways. Methylglyoxal mainly arises as side products of glycolysis involving glyceraldehyde-3-phosphate and dihydroxyacetone phosphate. It is also thought to arise via the degradation of acetone and threonine. Illustrative of the myriad pathways to MGO, aristolochic acid caused 12-fold increase of methylglyoxal from 18 to 231 μg/mg of kidney protein in poisoned mice. It may form from 3-aminoacetone, which is an intermediate of threonine catabolism, as well as through lipid peroxidation. However, the most important source is glycolysis. Here, methylglyoxal arises from nonenzymatic phosphate elimination from glyceraldehyde phosphate and dihydroxyacetone phosphate (DHAP), two intermediates of glycolysis. This conversion is the basis of a potential biotechnological route to the commodity chemical 1,2-propanediol.
Since methylglyoxal is highly cytotoxic, several detoxification mechanisms have evolved. One of these is the glyoxalase system. Methylglyoxal is detoxified by glutathione. Glutathione reacts with methylglyoxal to give a hemithioacetal, which converted into S--lactoyl-glutathione by glyoxalase I. This thioester is hydrolyzed to -lactate by glyoxalase II.
Biochemical function
Methylglyoxal is involved in the formation of advanced glycation end products (AGEs). |
https://en.wikipedia.org/wiki/Rotronics%20Wafadrive | The Rotronics Wafadrive is a magnetic tape storage peripheral launched in late 1984 for the ZX Spectrum home computer. Each tape is a continuous loop, unlike cassette tape. It was intended to compete with Sinclair's ZX Interface 1 and ZX Microdrive.
The Wafadrive comprises two continuous loop stringy floppy tape drives, an RS-232 interface and Centronics parallel port. The drives can run at two speeds: High speed (for seeking) and low speed (for reading/writing, which was significantly slower than that of Microdrives). The cartridges (or "wafers"), the same as those used in Entrepo stringy floppy devices for other microcomputers, are physically larger than Microdrive cartridges. They were available in three different capacities, nominally 16 kB, 64 kB or 128 kB. The larger sizes had the disadvantage of slower access, due to the longer length of tape.
The same drive mechanism, manufactured by BSR, and cartridges were used in at least the following similar devices:
Quick Data Drive (QDD), designed to connect to the cassette port of Commodore 64 and VIC-20 home computers.
A&J Micro Drive System 100, for TRS-80 Model 100 and it's clones (Kyotronic KC-85, NEC PC-8201 & PC-8300, Olivetti M10), connected via the RS-232 port.
External links
Rotronics Wafadrive User Manual
meulie.net Rotronics Wafadrive User Manual
archive.org/sincuser.f9.co.uk Review of Wafadrive in Sinclair User, December 1984
Review of Waferdrive in Your Sinclair, Issue 5, May 1986
Computer storage devices
Home computer peripherals
ZX Spectrum |
https://en.wikipedia.org/wiki/Hasse%E2%80%93Witt%20matrix | In mathematics, the Hasse–Witt matrix H of a non-singular algebraic curve C over a finite field F is the matrix of the Frobenius mapping (p-th power mapping where F has q elements, q a power of the prime number p) with respect to a basis for the differentials of the first kind. It is a g × g matrix where C has genus g. The rank of the Hasse–Witt matrix is the Hasse or Hasse–Witt invariant.
Approach to the definition
This definition, as given in the introduction, is natural in classical terms, and is due to Helmut Hasse and Ernst Witt (1936). It provides a solution to the question of the p-rank of the Jacobian variety J of C; the p-rank is bounded by the rank of H, specifically it is the rank of the Frobenius mapping composed with itself g times. It is also a definition that is in principle algorithmic. There has been substantial recent interest in this as of practical application to cryptography, in the case of C a hyperelliptic curve. The curve C is superspecial if H = 0.
That definition needs a couple of caveats, at least. Firstly, there is a convention about Frobenius mappings, and under the modern understanding what is required for H is the transpose of Frobenius (see arithmetic and geometric Frobenius for more discussion). Secondly, the Frobenius mapping is not F-linear; it is linear over the prime field Z/pZ in F. Therefore the matrix can be written down but does not represent a linear mapping in the straightforward sense.
Cohomology
The interpretation for sheaf cohomology is this: the p-power map acts on
H1(C,OC),
or in other words the first cohomology of C with coefficients in its structure sheaf. This is now called the Cartier–Manin operator (sometimes just Cartier operator), for Pierre Cartier and Yuri Manin. The connection with the Hasse–Witt definition is by means of Serre duality, which for a curve relates that group to
H0(C, ΩC)
where ΩC = Ω1C is the sheaf of Kähler differentials on C.
Abelian varieties and their p-rank
The p-rank of an abel |
https://en.wikipedia.org/wiki/Topographical%20code | In medicine, "topographical codes" (or "topography codes") are codes that indicate a specific location in the body.
Examples
Only the first of these is a system dedicated only to topography. The others are more generalized systems that contain topographic axes.
Nomina Anatomica (updated to Terminologia Anatomica)
ICD-O
SNOMED
MeSH (the 'A' axis)
See also
Medical classification |
https://en.wikipedia.org/wiki/Proceedings%20of%20the%20Physical%20Society | The Proceedings of the Physical Society was a journal on the subject of physics, originally associated with the Physical Society of London, England. In 1968, it was replaced by the Journal of Physics.
Journal history
1874–1925: Proceedings of the Physical Society of London
1926–1948: Proceedings of the Physical Society
1949–1957: Proceedings of the Physical Society, Section A
1949–1957: Proceedings of the Physical Society, Section B
1958–1967: Proceedings of the Physical Society
External links
Electronic access from the Institute of Physics (IoP)
Physics journals
IOP Publishing academic journals
Academic journals associated with learned and professional societies of the United Kingdom
Defunct journals of the United Kingdom |
https://en.wikipedia.org/wiki/Physical%20Society%20of%20London | The Physical Society of London, England, was a scientific society which was founded in 1874. In 1921, it was renamed the Physical Society, and in 1960 it merged with the Institute of Physics (IOP), the combined organisation eventually adopting the name of the latter society.
The society was founded due to the efforts of Frederick Guthrie, Professor of Physics at the Royal College of Science, South Kensington, and his assistant, William Fletcher Barrett. They canvassed support for a 'Society for physical research' and on 14 February 1874, the Physical Society of London was formed with an initial membership of 29 people. The Society's first president was John Hall Gladstone.
Meetings were held every two weeks, mainly at Imperial College London. From its beginning, the society held open meetings and demonstrations and published Proceedings of the Physical Society of London. The first Guthrie lecture, now known as the Faraday Medal and Prize, was delivered in 1914. In 1921 the society became the Physical Society, and in 1932 absorbed the Optical Society (of London). The Optical Society published Transactions of the Optical Society from 1899 to 1932.
In 1960, the merger with the Institute of Physics took place, creating the Institute of Physics and the Physical Society, which combined the learned society tradition of the Physical Society with the professional body tradition of the Institute of Physics. Upon being granted a royal charter in 1970, the organisation renamed itself as the Institute of Physics.
Presidents of the Physical Society
1874–1876 John H. Gladstone
1876–1878 George C. Foster
1878–1880 William G Adams
1880–1882 The Lord Kelvin of Largs
1882–1884 Robert B. Clifton
1884–1886 Frederick Guthrie
1886–1888 Balfour Stewart
1888–1890 Arnold W. Reinold
1890–1892 William E. Ayrton
1892–1893 George F. FitzGerald
1893–1895 Arthur W. Rucker
1895–1897 William de W. Abney
1897–1899 Shelford Bidwell
1899–1901 Oliver J. Lodge
1901–1903 Silvanus P. Thompson
1903–190 |
https://en.wikipedia.org/wiki/Hasse%20invariant%20of%20a%20quadratic%20form | In mathematics, the Hasse invariant (or Hasse–Witt invariant) of a quadratic form Q over a field K takes values in the Brauer group Br(K). The name "Hasse–Witt" comes from Helmut Hasse and Ernst Witt.
The quadratic form Q may be taken as a diagonal form
Σ aixi2.
Its invariant is then defined as the product of the classes in the Brauer group of all the quaternion algebras
(ai, aj) for i < j.
This is independent of the diagonal form chosen to compute it.
It may also be viewed as the second Stiefel–Whitney class of Q.
Symbols
The invariant may be computed for a specific symbol φ taking values in the group C2 = {±1}.
In the context of quadratic forms over a local field, the Hasse invariant may be defined using the Hilbert symbol, the unique symbol taking values in C2. The invariants of a quadratic forms over a local field are precisely the dimension, discriminant and Hasse invariant.
For quadratic forms over a number field, there is a Hasse invariant ±1 for every finite place. The invariants of a form over a number field are precisely the dimension, discriminant, all local Hasse invariants and the signatures coming from real embeddings.
See also
Hasse–Minkowski theorem |
https://en.wikipedia.org/wiki/Remote%20File%20Sharing | Remote File Sharing (RFS) is a Unix operating system component for sharing resources, such as files, devices, and file system directories, across a network, in a network-independent manner, similar to a distributed file system. It was developed at Bell Laboratories of AT&T in the 1980s, and was first delivered with UNIX System V Release 3 (SVR3). RFS relied on the STREAMS Transport Provider Interface feature of this operating system. It was also included in UNIX System V Release 4, but as that also included the Network File System (NFS) which was based on TCP/IP and more widely supported in the computing industry, RFS was little used. Some licensees of AT&T UNIX System V Release 4 did not include RFS support in SVR4 distributions, and Sun Microsystems removed it from Solaris 2.4.
Features
The basic application architecture of RFS is the client–server model, in which a participating host may be a server as well as a client, simultaneously. It was based on different design decisions, in comparison to the Network File System (NFS). Instead of focusing on reliable operation in the presence of failures, it focused on preserving UNIX file system semantics across the network. This enabled the system to provide remote access to hardware resources located on an RFS server. Unlike NFS (before version 4), the RFS server maintains state to keep track of how many times a file has been opened, or the locks established on a file or device.
RFS provides complete UNIX/POSIX file semantics for all file types, including special devices, and named pipes. It supports access controls and record and file locking of remote files in a transparent manner as if the shared files are local. This permitted binary application compatibility when involving network resources. It allows the mounting of devices across the network. For example, /dev/cdrom can be accessed remotely, as if it were a local resource. Access to any specific file or a file system directory is transparent across the network, |
https://en.wikipedia.org/wiki/Debadging | The term debadging refers to the process of removing the manufacturer's emblems from a vehicle. Common emblems to be removed include the manufacturer's logo as well as the emblems designating the model of the vehicle.
Often debadging is done to complement the smoothed-out bodywork of a modified car, or to disguise a lower-specification model. Some people driving high-end luxury cars, do it not to flaunt the fact their car is any different from any other model and remove the badge. In Europe in particular, it is a common request for purchasers of high-end models of cars like BMW or Mercedes-Benz, etc. to have the emblems removed. Many automotive enthusiasts also believe that debadging a vehicle makes it easier to clean. This is because manufacturer badges are notorious for trapping wax, which is difficult to remove from small crevices. Also, sleepers are sometimes debadged to disguise any subtle evidence of a high performance vehicle.
Another common reason for debadging is to rid the car of its commercial advertising. Drivers are not being paid to advertise the brand, so some decide to remove this commercial aspect of the vehicle. Similarly, film, television and advertising companies may elect to have vehicles debadged in a work to avoid implying product placement or endorsement of a particular vehicle marque.
While most modern vehicle emblems are attached with adhesive and can be easily removed, some emblems require varying degrees of bodywork to fill in voids and mounting holes left behind.
Debadging can also refer to the process of removing the car manufacturer's logo from the front grille. The grille is often replaced by a plain grille, or a grille from another make and model of car altogether or one showing the more subtle logo of an aftermarket manufacturer such as ABT, Irmscher or Kamei. This is a common customising technique on leadsleds and kustoms, which dates back to the 1940s.
Criminals have been known to debadge a car before using it for crimes |
https://en.wikipedia.org/wiki/Enriques%E2%80%93Kodaira%20classification | In mathematics, the Enriques–Kodaira classification is a classification of compact complex surfaces into ten classes. For each of these classes, the surfaces in the class can be parametrized by a moduli space. For most of the classes the moduli spaces are well understood, but for the class of surfaces of general type the moduli spaces seem too complicated to describe explicitly, though some components are known.
Max Noether began the systematic study of algebraic surfaces, and Guido Castelnuovo proved important parts of the classification. described the classification of complex projective surfaces. later extended the classification to include non-algebraic compact surfaces. The analogous classification of surfaces in positive characteristic was begun by and completed by ; it is similar to the characteristic 0 projective case, except that one also gets singular and supersingular Enriques surfaces in characteristic 2, and quasi-hyperelliptic surfaces in characteristics 2 and 3.
Statement of the classification
The Enriques–Kodaira classification of compact complex surfaces states that every nonsingular minimal compact complex surface is of exactly one of the 10 types listed on this page; in other words, it is one of the rational, ruled (genus > 0), type VII, K3, Enriques, Kodaira, toric, hyperelliptic, properly quasi-elliptic, or general type surfaces.
For the 9 classes of surfaces other than general type, there is a fairly complete description of what all the surfaces look like (which for class VII depends on the global spherical shell conjecture, still unproved in 2009). For surfaces of general type not much is known about their explicit classification, though many examples have been found.
The classification of algebraic surfaces in positive characteristic (, ) is similar to that of algebraic surfaces in characteristic 0, except that there are no Kodaira surfaces or surfaces of type VII, and there are some extra families of Enriques surfaces in characterist |
https://en.wikipedia.org/wiki/Cross-interleaved%20Reed%E2%80%93Solomon%20coding | In the compact disc system, cross-interleaved Reed–Solomon code (CIRC) provides error detection and error correction. CIRC adds to every three data bytes one redundant parity byte.
Overview
Reed–Solomon codes are specifically useful in combating mixtures of random and burst errors. CIRC corrects error bursts up to 3,500 bits in sequence (2.4 mm in length as seen on CD surface) and compensates for error bursts up to 12,000 bits (8.5 mm) that may be caused by minor scratches.
Characteristics
High random error correctability
Long burst error correctability
In case the burst correction capability is exceeded, interpolation may provide concealment by approximation
Simple decoder strategy possible with reasonably-sized external random access memory
Very high efficiency
Room for future introduction of four audio channels without major changes in the format (as of 2023, this has not been implemented).
Interleave
Errors found in compact discs (CDs) are a combination of random and burst errors. In order to alleviate the strain on the error control code, some form of interleaving is required. The CD system employs two concatenated Reed–Solomon codes, which are interleaved cross-wise. Judicious positioning of the stereo channels as well as the audio samples on even or odd-number instants within the interleaving scheme, provide the error concealment ability, and the multitude of interleave structures used on the CD makes it possible to correct and detect errors with a relatively low amount of redundancy.
See also
Multiplexing
Parity (mathematics)
Parity (telecommunication)
Checksum |
https://en.wikipedia.org/wiki/Fasciitis | Fasciitis is an inflammation of the fascia, which is the connective tissue surrounding muscles, blood vessels and nerves.
In particular, it often involves one of the following diseases:
Necrotizing fasciitis
Plantar fasciitis
Ischemic fasciitis, classified by the World Health Organization, 2020, as a specific tumor form in the category of fibroblastic and myofibroblastic tumors.
Eosinophilic fasciitis
Paraneoplastic fasciitis |
https://en.wikipedia.org/wiki/Knowledge-based%20engineering | Knowledge-based engineering (KBE) is the application of knowledge-based systems technology to the domain of manufacturing design and production. The design process is inherently a knowledge-intensive activity, so a great deal of the emphasis for KBE is on the use of knowledge-based technology to support computer-aided design (CAD) however knowledge-based techniques (e.g. knowledge management) can be applied to the entire product lifecycle.
The CAD domain has always been an early adopter of software-engineering techniques used in knowledge-based systems, such as object-orientation and rules. Knowledge-based engineering integrates these technologies with CAD and other traditional engineering software tools.
Benefits of KBE include improved collaboration of the design team due to knowledge management, improved re-use of design artifacts, and automation of major parts of the product lifecycle.
Overview
KBE is essentially engineering on the basis of knowledge models. A knowledge model uses knowledge representation to represent the artifacts of the design process (as well as the process itself) rather than or in addition to conventional programming and database techniques.
The advantages to using knowledge representation to model industrial engineering tasks and artifacts are:
Improved integration. In traditional CAD and industrial systems each application often has its own slightly different model. Having a standardized knowledge model makes integration easier across different systems and applications.
More re-use. A knowledge model facilitates storing and tagging design artifacts so that they can easily be found again and re-used. Also, knowledge models are themselves more re-usable by virtue of using formalism such as IS-A relations (classes and subclasses in the object-oriented paradigm). With subclassing it can be very easy to create new types of artifacts and processes by starting with an existing class and adding a new subclass that inherits all the default |
https://en.wikipedia.org/wiki/SLITRK1 | SLITRK1 ("SLIT and NTRK-like family, member 1") is a human gene that codes for a transmembrane and signalling protein that is part of the SLITRK gene family, which is responsible for synapse regulation and presynaptic differentiation in the brain. Expression of the gene has been linked to early formation of excitatory synapses through binding with receptor tyrosine phosphatase PTP (LAR-RPTP). Various studies over the years have linked mutations in the gene to conditions on the OCD spectrum, Tourette syndrome and trichotillomania, however the mutations in the genome itself vary greatly between individuals, with most mutations observed being hard to find in repeat studies.
Members of the SLITRK family, such as SLITRK1, are integral membrane proteins with 2 N-terminal leucine-rich repeat (LRR) domains similar to those of SLIT proteins (see SLIT1; MIM 603742). Most SLITRKs, but not SLITRK1, also have C-terminal regions that share homology with neurotrophin receptors (see NTRK1; MIM 191315). SLITRKs are expressed predominantly in neural tissues and have neurite-modulating activity (Aruga et al., 2003).
Gene
The gene for SLITRK1 is located on chromosome 13q31.1. The gene is expressed only in the brain of humans. The mRNA can differ from alternative splicing, and contains domains for the extracellular matrix as well as for the LRRs. Mice contain an ortholog of the gene called Slitrk1.
Protein structure
SLITRK1 contains 2 horseshoe shaped leucine rich repeat domains (LRRs) in its extracellular domain which are vital to its function. The LRRs have 6 modules each and are connected by a 70-90 amino acid loops. LRR1 is a more conserved sequence and is present as a dimer while LRR2 is a monomer and has a more variable sequence. The conserved sequence of LRR1 contains critical binding pockets and specific charged residues that are important for it to carry out its function of binding to LAR-RPTPs on the N-terminus. Both LRR sequences are randomly positioned on the protein a |
https://en.wikipedia.org/wiki/Acute%20interstitial%20pneumonitis | Acute interstitial pneumonitis (also known as acute interstitial pneumoniais a rare, severe lung disease that usually affects otherwise healthy individuals. There is no known cause or cure.
Acute interstitial pneumonitis is often categorized as both an interstitial lung disease and a form of acute respiratory distress syndrome (ARDS). In uncommon instances, if ARDS appears acutely, in the absence of known triggers, and follows a rapidly progressing clinical course, the term "Acute interstitial pneumonia" is used. ARDS is distinguished from the chronic forms of interstitial pneumonia such as idiopathic pulmonary fibrosis.
Symptoms and signs
The most common symptoms of acute interstitial pneumonitis are highly productive cough with expectoration of thick mucus, fever, and difficulties breathing. These often occur over a period of one to two weeks before medical attention is sought. The presence of fluid means the person experiences a feeling similar to 'drowning'. Difficulties breathing can quickly progress to an inability to breathe without support (respiratory failure).
Acute interstitial pneumonitis typically progresses rapidly, with hospitalization and mechanical ventilation often required only days to weeks after initial symptoms of cough, fever, and difficulties breathing develop.
Diagnosis
Rapid progression from initial symptoms to respiratory failure is a key feature. An X-ray that shows ARDS is necessary for diagnosis (fluid in the small air sacs (alveoli) in both lungs). In addition, a biopsy of the lung that shows organizing diffuse alveolar damage is required for diagnosis. This type of alveolar damage can be attributed to nonconcentrated and nonlocalized alveoli damage, marked alveolar septal edema with inflammatory cell infiltration, fibroblast proliferation, occasional hyaline membranes, and thickening of the alveolar walls. The septa are lined with atypical, hyperplastic type II pneumocytes, thus leading to the collapse of airspaces. Other diagn |
https://en.wikipedia.org/wiki/Phoenix%20Technologies | Phoenix Technologies Ltd is an American company that designs, develops and supports core system software for personal computers and other computing devices. The company's products commonly referred to as BIOS (Basic Input/Output System) or firmware support and enable the compatibility, connectivity, security and management of the various components and technologies used in such devices. Phoenix Technologies and IBM developed the El Torito standard.
Phoenix was incorporated in Massachusetts in September 1979, and its headquarters are in Campbell, California.
History
In 1979, Neil Colvin formed what was then called Phoenix Software Associates after his prior employer, Xitan, went out of business. Neil hired Dave Hirschman, a former Xitan employee. During 1980–1981, they rented office space for the first official Phoenix location at 151 Franklin Street, Boston, Massachusetts.
In this same time period Phoenix purchased a non-exclusive license for Seattle Computer Products 86-DOS. Phoenix developed customized versions of 86-DOS (or sometimes called PDOS for Phoenix DOS) for various microprocessor platforms. Phoenix also provided PMate as a replacement for Edlin as the DOS file editor. Phoenix also developed C language libraries, called PForCe, along with Plink-86/Plink-86plus, overlay linkers, and Pfix-86, a windowed Debugger for DOS. These products only provided a small revenue stream to Phoenix during the early 1980s and the company did not significantly expand in size.
Cloning the IBM PC BIOS
After the success of the IBM PC, many companies began making PC clones. Some, like Compaq, developed their own compatible ROM BIOS, but others violated copyright by directly copying the PC's BIOS from the IBM PC Technical Reference Manual. After Apple Computer, Inc. v. Franklin Computer Corp. IBM sued companies that it claimed infringed IBM's copyright. Clone manufacturers needed a legal, fully compatible BIOS.
To develop a legal BIOS, Phoenix used a clean room design. Eng |
https://en.wikipedia.org/wiki/Goldberger%E2%80%93Wise%20mechanism | In particle physics, the Goldberger–Wise mechanism is a popular mechanism that determines the size of the fifth dimension in Randall–Sundrum models. The mechanism uses a scalar field that propagates throughout the five-dimensional bulk. On each of the branes that end the fifth dimension (frequently referred to as the Planck brane and TeV brane, respectively) there is a potential for this scalar field. The minima for the potentials on the Planck brane and TeV brane are different and causes the vacuum expectation value of the scalar field to change throughout the fifth dimension. This configuration generates a potential for the radion causing it to have a vacuum expectation value and a mass. With reasonable values for the scalar potential, the size of the extra dimension is large enough to solve the hierarchy problem. |
https://en.wikipedia.org/wiki/Fuzzy%20sphere | In mathematics, the fuzzy sphere is one of the simplest and most canonical examples of non-commutative geometry. Ordinarily, the functions defined on a sphere form a commuting algebra. A fuzzy sphere differs from an ordinary sphere because the algebra of functions on it is not commutative. It is generated by spherical harmonics whose spin l is at most equal to some j. The terms in the product of two spherical harmonics that involve spherical harmonics with spin exceeding j are simply omitted in the product. This truncation replaces an infinite-dimensional commutative algebra by a -dimensional non-commutative algebra.
The simplest way to see this sphere is to realize this truncated algebra of functions as a matrix algebra on some finite-dimensional vector space.
Take the three j-dimensional matrices that form a basis for the j dimensional irreducible representation of the Lie algebra su(2). They satisfy the relations , where is the totally antisymmetric symbol with , and generate via the matrix product the algebra of j dimensional matrices. The value of the su(2) Casimir operator in this representation is
where I is the j-dimensional identity matrix.
Thus, if we define the 'coordinates'
where r is the radius of the sphere and k is a parameter, related to r and j by , then the above equation concerning the Casimir operator can be rewritten as
,
which is the usual relation for the coordinates on a sphere of radius r embedded in three dimensional space.
One can define an integral on this space, by
where F is the matrix corresponding to the function f.
For example, the integral of unity, which gives the surface of the sphere in the commutative case is here equal to
which converges to the value of the surface of the sphere if one takes j to infinity.
Notes
Jens Hoppe, "Membranes and Matrix Models", lectures presented during the summer school on ‘Quantum Field Theory – from a Hamiltonian Point of View’, August 2–9, 2000,
John Madore, An introduction |
https://en.wikipedia.org/wiki/Hohlraum | In radiation thermodynamics, a hohlraum (a non-specific German word for a "hollow space" or "cavity") is a cavity whose walls are in radiative equilibrium with the radiant energy within the cavity. This idealized cavity can be approximated in practice by making a small perforation in the wall of a hollow container of any opaque material. The radiation escaping through such a perforation will be a good approximation to black-body radiation at the temperature of the interior of the container.
Inertial confinement fusion
The indirect drive approach to inertial confinement fusion is as follows: the fusion fuel capsule is held inside a cylindrical hohlraum. The hohlraum body is manufactured using a high-Z (high atomic number) element, usually gold or uranium.
Inside the hohlraum is a fuel capsule containing deuterium and tritium (D-T) fuel. A frozen layer of D-T ice adheres inside the fuel capsule.
The fuel capsule wall is synthesized using light elements such as plastic, beryllium, or high density carbon, i.e. diamond. The outer portion of the fuel capsule explodes outward when ablated by the x-rays produced by the hohlraum wall upon irradiation by lasers. Due to Newton's third law, the inner portion of the fuel capsule implodes, causing the D-T fuel to be supercompressed, activating a fusion reaction.
The radiation source (e.g., laser) is pointed at the interior of the hohlraum rather than at the fuel capsule itself. The hohlraum absorbs and re-radiates the energy as X-rays, a process known as indirect drive. The advantage to this approach, compared to direct drive, is that high mode structures from the laser spot are smoothed out when the energy is re-radiated from the hohlraum walls. The disadvantage to this approach is that low mode asymmetries are harder to control. It is important to be able to control both high mode and low mode asymmetries to achieve a uniform implosion.
The hohlraum walls must have surface roughness less than 1 micron, and hence accurate |
https://en.wikipedia.org/wiki/INT%2013H | INT 13h is shorthand for BIOS interrupt call 13hex, the 20th interrupt vector in an x86-based (IBM PC-descended) computer system. The BIOS typically sets up a real mode interrupt handler at this vector that provides sector-based hard disk and floppy disk read and write services using cylinder-head-sector (CHS) addressing. Modern PC BIOSes also include INT 13h extension functions, originated by IBM and Microsoft in 1992, that provide those same disk access services using 64-bit LBA addressing; with minor additions, these were quasi-standardized by Phoenix Technologies and others as the EDD (Enhanced Disk Drive) BIOS extensions.
INT is an x86 instruction that triggers a software interrupt, and 13hex is the interrupt number (as a hexadecimal value) being called.
Modern computers come with both BIOS INT 13h and UEFI functionality that provides the same services and more, with the exception of UEFI Class 3 that completely removes CSM thus lacks INT 13h and other interrupts. Typically, UEFI drivers use LBA-addressing instead of CHS-addressing.
Overview
Under real mode operating systems, such as DOS, calling INT 13h would jump into the computer's ROM-BIOS code for low-level disk services, which would carry out physical sector-based disk read or write operations for the program. In DOS, it serves as the low-level interface for the built-in block device drivers for hard disks and floppy disks. This allows INT 25h and INT 26h to provide absolute disk read/write functions for logical sectors to the FAT file system driver in the DOS kernel, which handles file-related requests through DOS API (INT 21h) functions.
Under protected mode operating systems, such as Microsoft Windows NT derivatives (e.g. NT4, 2000, XP, and Server 2003) and Linux with dosemu, the OS intercepts the call and passes it to the operating system's native disk I/O mechanism. Windows 9x and Windows for Workgroups 3.11 also bypass BIOS routines when using 32-bit Disk Access. Besides performing low-level d |
https://en.wikipedia.org/wiki/Wine%20fault | A wine fault is a sensory-associated (organoleptic) characteristic of a wine that is unpleasant, and may include elements of taste, smell, or appearance, elements that may arise from a "chemical or a microbial origin", where particular sensory experiences (e.g., an off-odor) might arise from more than one wine fault. Wine faults may result from poor winemaking practices or storage conditions that lead to wine spoilage.
In the case of a chemical origin, many compounds causing wine faults are already naturally present in wine, but at insufficient concentrations to be of issue, and in fact may impart positive characters to the wine; however, when the concentration of such compounds exceed a sensory threshold, they replace or obscure desirable flavors and aromas that the winemaker wants the wine to express. The ultimate result is that the quality of the wine is reduced (less appealing, sometimes undrinkable), with consequent impact on its value.<ref name="Baldy pp 37-39, et al">M. Baldy: "The University Wine Course", Third Edition, pp. 37-39, 69-80, 134-140. The Wine Appreciation Guild 2009 .</ref>
There are many underlying causes of wine faults, including poor hygiene at the winery, excessive or insufficient exposure of the wine to oxygen, excessive or insufficient exposure of the wine to sulphur, overextended maceration of the wine either pre- or post-fermentation, faulty fining, filtering and stabilization of the wine, the use of dirty oak barrels, over-extended barrel aging and the use of poor quality corks. Outside of the winery, other factors within the control of the retailer or end user of the wine can contribute to the perception of flaws in the wine. These include poor storage of the wine that exposes it to excessive heat and temperature fluctuations as well as the use of dirty stemware during wine tasting that can introduce materials or aromas to what was previously a clean and fault-free wine.
Differences between flaws and faults
In wine tasting, there is |
https://en.wikipedia.org/wiki/WWWJDIC | WWWJDIC is an online Japanese dictionary based on the electronic dictionaries compiled and collected by Australian academic Jim Breen. The main Japanese–English dictionary file (EDICT) contains over 180,000 entries, and the ENAMDICT dictionary contains over 720,000 Japanese surnames, first names, place names and product names. WWWJDIC also contains several specialized dictionaries covering topics such as life sciences, law, computing, engineering, etc.
For example sentences with Japanese words, WWWJDIC makes use of a sentence database from the Tatoeba project, largely based on the Tanaka Corpus. Unlike the original Tanaka Corpus, the sentences from the Tatoeba project are not public domain, but are available under the non-restrictive CC-BY license. The sentence collection contains over 150,000 sentence pairs in Japanese and English.
In addition to Japanese–English, the dictionary has Japanese paired with German, French, Russian, Hungarian, Swedish, Spanish and Dutch. However, currently there are no example sentences for these languages.
The dictionary is updated freely and may be copied under its own licence arrangements.
Several mirror sites of the main WWWJDIC also exist around the world. These sites update daily from the home site at the Electronic Dictionary Research and Development Group (EDRDG).
See also
Japanese language education |
https://en.wikipedia.org/wiki/Panderichthys | Panderichthys is a genus of extinct sarcopterygian (lobe-finned fish) from the late Devonian period, about 380 Mya. Panderichthys, which was recovered from Frasnian (early Late Devonian) deposits in Latvia, is represented by two species. P. stolbovi is known only from some snout fragments and an incomplete lower jaw. P. rhombolepis is known from several more complete specimens. Although it probably belongs to a sister group of the earliest tetrapods, Panderichthys exhibits a range of features transitional between tristichopterid lobe-fin fishes (e.g., Eusthenopteron) and early tetrapods. It is named after the German-Baltic paleontologist Christian Heinrich Pander. Possible tetrapod tracks dating back to before the appearance of Panderichthys in the fossil record were reported in 2010, which suggests that Panderichthys is not a direct ancestor of tetrapods, but nonetheless shows the traits that evolved during the fish-tetrapod evolution
Discovery and history
Panderichthys is represented by two different species: Panderichthys rhombolepis and Panderichthys stobolvi. P. rhombolepis was discovered by Gross in 1930 and P. stobolvi was discovered and figured by Emilia Vorobyeva in 1960. P. Grhombolepis was discovered in Lode, Latvia within Frasnian deposits and according to P.E. Ahlberg can definitely be found in other Frasnian deposits in Latvia. Although fossils of Panderichthys have been known for a long time, but they have only recently been examined in full. The first time they were recognized as being phylogenetically closer to tetrapods than fish was by Shultze and Arsenault in 1985.
Description
Panderichthys is a long fish with a large tetrapod-like head that is flattened, narrow at the snout and wide in the back. The intracranial joint, which is characteristic of most lobe-fin fishes, has been lost from the external elements of the skull, but is still present in the braincase. The patterns of external bones in the skull roof and cheeks are more similar to tho |
https://en.wikipedia.org/wiki/Victor%20Glushkov | Victor Mikhailovich Glushkov (; August 24, 1923 – January 30, 1982) was a Soviet mathematician, the founding father of information technology in the Soviet Union and one of the founding fathers of Soviet cybernetics.
He was born in Rostov-on-Don, Russian SFSR, in the family of a mining engineer. Glushkov graduated from Rostov State University in 1948, and in 1952 proposed solutions to Hilbert's fifth problem and defended his thesis in Moscow State University.
In 1956 he began working with computers and worked in Kyiv as a Director of the Computational Center of the Academy of Science of Ukraine. In 1958 he became a member of the Communist Party. In 1962 Glushkov established the famous Institute of Cybernetics of the National Academy of Science of Ukraine and became its first director.
He made contributions to the theory of automata. He and his followers (Kapitonova, Letichevskiy and other) successfully applied that theory to enhance construction of computers. His book on that topic "Synthesis of Digital Automata" became well known. For that work, he was awarded the Lenin Prize in 1964 and elected as a Member of the Academy of Science of USSR.
He greatly influenced many other fields of theoretical computer science (including the theory of programming and artificial intelligence) as well as its applications in the USSR. He published nearly 800 printed works.
One of his great practical goals was the creation of the National Automated System for Computation and Information Processing (OGAS), consisting of a computer network to manage the allocation of resources and information among organizations in the national economy, which would represent a higher form of socialist planning than the extant centrally planned economy. This ambitious project was ahead of its time, first being proposed and modeled in 1962. It received opposition from many senior Communist Party leaders who felt the system threatened Party control of the economy. By the early 1970s official interes |
https://en.wikipedia.org/wiki/Edward%20Ginzton | Edward Leonard Ginzton (December 27, 1915 – August 13, 1998) was a Ukrainian-American engineer.
Education
Ginzton completed his B.S. (1936) and M.S. (1937) in Electrical Engineering at the University of California, Berkeley, and his Ph.D. in electrical engineering from Stanford University in 1941.
Career
As a student at Stanford University, Ginzton worked with William Hansen and brothers Russell and Sigurd Varian. In 1941 he became a member of the Varian–Hansen group at the Sperry Gyroscope Company.
Ginzton was appointed assistant professor in physics at Stanford University in 1945 and remained on the faculty until 1961.
In 1949, Ginzton and Marvin Chodorow developed the 1 BeV 220-foot accelerator at Stanford University. After completion of the 1 BeV accelerator, Ginzton became director of the Microwave Laboratory, which was later renamed the Ginzton Laboratory.
Ginzton, along with Russell and Sigurd Varian, was one of the original board members of Varian Associates, founded in 1948. The nine initial directors of the company were Ginzton, Russell, Sigurd, and Dorothy Varian, H. Myrl Stearns, Stanford University faculty members William Webster Hansen, and Leonard I. Schiff, legal counsel Richard M. Leonard, and patent attorney Paul B. Hunter.
Ginzton became CEO and chairman of Varian Associates after Russell Varian died of a heart attack and Sigurd Varian died in a plane crash.
Ginzton was awarded the IEEE Medal of Honor in 1969 for "his outstanding contributions in advancing the technology of high power klystrons and their application, especially to linear particle accelerators."
Ginzton was a member of the National Academy of Engineering and in the National Academy of Sciences.
Ginzton's biography is available online.
Family
Ginzton was born in Ukraine and lived in China before moving to California in 1929.
On June 16, 1939, Ginzton and Artemas Alma McCann (1913–2000) married. Artemas was the daughter of James Arthur and Alma (Hawes) McCann. The Ginz |
https://en.wikipedia.org/wiki/Olga%20Oleinik | Olga Arsenievna Oleinik (also as Oleĭnik) HFRSE () (2 July 1925 – 13 October 2001) was a Soviet mathematician who conducted pioneering work on the theory of partial differential equations, the theory of strongly inhomogeneous elastic media, and the mathematical theory of boundary layers. She was a student of Ivan Petrovsky. She studied and worked at the Moscow State University.
She received many prizes for her remarkable contributions: the Chebotarev Prize in 1952; the State Prize 1988; the Petrowsky Prize in 1995; and the Prize of the Russian Academy of Sciences in 1995. Also she was member of several foreign academies of sciences, and earned several honorary degrees.
Life
On 2 May 1985 Olga Oleinik was awarded the laurea honoris causa by the Sapienza University of Rome, jointly with Fritz John.
Work
Research activity
She authored more than 370 mathematical publications and 8 monographs, as the sole author or in collaboration with others: her work covers algebraic geometry, the theory of partial differential equations where her work enlightened various aspects, elasticity theory and boundary layers theory.
Teaching activity
She was an enthusiast and very active teacher, advising the thesis of 57 "candidates".
Selected publications of Olga Oleinik
. An important paper where the author describes generalized solutions of nonlinear partial differential equations as BV functions.
. An important paper where the author constructs a weak solution in BV for a nonlinear partial differential equation with the method of vanishing viscosity.
. An important paper in the theory of the Stefan problem: generalizing earlier work of her doctoral student S. L. Kamenomostskaya, the author proves the existence of a generalized solution for the multi dimensional model.
(reviews of the Russian edition).
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See also
Boundary layer
Bounded variation
Elasticity theory
Homogenization
Partial differential equations
Stefan problem
Weak solutions
Notes |
https://en.wikipedia.org/wiki/Nikolai%20Chebotaryov | Nikolai Grigorievich Chebotaryov (often spelled Chebotarov or Chebotarev, , ) ( – 2 July 1947) was a Soviet mathematician. He is best known for the Chebotaryov density theorem.
He was a student of Dmitry Grave, a Russian mathematician. Chebotaryov worked on the algebra of polynomials, in particular examining the distribution of the zeros. He also studied Galois theory and wrote a textbook on the subject titled Basic Galois Theory.
His ideas were used by Emil Artin to prove the Artin reciprocity law.
He worked with his student Anatoly Dorodnov on a generalization of the quadrature of the lune, and proved the conjecture now known as the Chebotaryov theorem on roots of unity.
Early life
Nikolai Chebotaryov was born on 15 June 1894 in Kamianets-Podilskyi, Russian Empire (now in Ukraine). He entered the department of physics and mathematics at Kyiv University in 1912. In 1928 he became a professor at Kazan University, remaining there for the rest of his life. He died on 2 July 1947. He was an atheist. On 14 May 2010 a memorial plaque for Nikolai Chebotaryov was unveiled on the main administration building of I.I. Mechnikov Odessa National University. |
https://en.wikipedia.org/wiki/Jan%20%C5%9Aleszy%C5%84ski | Ivan Vladislavovich Sleshinsky or Jan Śleszyński () (23 July 1854 – 9 March 1931) was a Polish-Russian mathematician. He was born in Lysianka, Russian Empire to Polish parents.
Life
Śleszyński's main work was on continued fractions, least squares and axiomatic proof theory based on mathematical logic. He and Alfred Pringsheim, working separately, proved what is now called the Śleszyński–Pringsheim theorem.
His most important publications include: "Teoria dowodu" ("The theory of proof") in two volumes (1925, 1929), and "Teoria wyznaczników" ("The theory of determinants") (1926). He is buried at Rakowicki Cemetery.
See also
History of philosophy in Poland
List of Poles |
https://en.wikipedia.org/wiki/Aegyptosaurus | Aegyptosaurus (meaning 'Egypt's lizard') is a genus of sauropod dinosaur that lived in what is now Africa, around 95 million years ago, during the Late Cretaceous Period (Cenomanian faunal stage).
Discovery and naming
The holotype (1912VIII61) consists of three caudal vertebrae, a partial scapula, and some limb bones, all of which were discovered in the Bahariya Formation of Egypt between 1910 and by Ernst Stromer and Richard Markgraf and the holotype was sent to Munich, Germany in 1915 to be studied at the same time the holotype of Spinosaurus aegyptiacus was described.
Aegyptosaurus was described by German paleontologist Ernst Stromer in 1932, seventeen years after the holotype was sent to Munich, and its fossils have been found in the Bahariya Formation of Egypt, the Farak Formation of Niger and in several other different locations in the Sahara Desert. The generic name, Aegyptosaurus, is derived from the country in which it was discovered and the Greek sauros meaning 'lizard'. All of the specimens destroyed in 1944 were discovered before 1939 and the fossils were stored together in Munich, but were obliterated when an Allied bombing raid destroyed the museum where they were kept on 25 April 1944, during World War II. Only fragments from other specimens still exist, mostly in the form of indeterminate specimens from Egypt and Niger.
de Lapparent (1960) referred a series of caudal vertebrae from the Continental intercalaire of Egypt to Aegyptosaurus baharijensis.
Description
In 2010, based on Paralititan and other related titanosaurs, Gregory S. Paul estimated the length of Aegyptosaurus at , and its weight at . |
https://en.wikipedia.org/wiki/Ciprian%20Manolescu | Ciprian Manolescu (born December 24, 1978) is a Romanian-American mathematician, working in gauge theory, symplectic geometry, and low-dimensional topology. He is currently a professor of mathematics at Stanford University.
Biography
Manolescu completed his first eight classes at School no. 11 Mihai Eminescu and his secondary education at Ion Brătianu High School in Piteşti. He completed his undergraduate studies and PhD at Harvard University under the direction of Peter B. Kronheimer. He was the winner of the Morgan Prize, awarded jointly by AMS-MAA-SIAM, in 2002. His undergraduate thesis was on Finite dimensional approximation in Seiberg–Witten theory, and his PhD thesis topic was A spectrum valued TQFT from the Seiberg–Witten equations.
In early 2013, he released a paper detailing a disproof of the triangulation conjecture for manifolds of dimension 5 and higher. For this paper, he received the E. H. Moore Prize from the American Mathematical Society.
Awards and honors
He was among the recipients of the Clay Research Fellowship (2004–2008).
In 2012, he was awarded one of the ten prizes of the European Mathematical Society for his work on low-dimensional topology, and particularly for his role in the development of combinatorial Heegaard Floer homology.
He was elected as a member of the 2017 class of Fellows of the American Mathematical Society "for contributions to Floer homology and the topology of manifolds".
In 2018, he was an invited speaker at the International Congress of Mathematicians (ICM) in Rio de Janeiro.
In 2020, he received a Simons Investigator Award. The citation reads: "Ciprian Manolescu works in low-dimensional topology and gauge theory. His research is centered on constructing new versions of Floer homology and applying them to questions in topology. With collaborators, he showed that many Floer-theoretic invariants are algorithmically computable. He also developed a new variant of Seiberg-Witten Floer homology, which he used to prove th |
https://en.wikipedia.org/wiki/Electronic%20lock | An electronic lock (or electric lock) is a locking device which operates by means of electric current. Electric locks are sometimes stand-alone with an electronic control assembly mounted directly to the lock. Electric locks may be connected to an access control system, the advantages of which include: key control, where keys can be added and removed without re-keying the lock cylinder; fine access control, where time and place are factors; and transaction logging, where activity is recorded. Electronic locks can also be remotely monitored and controlled, both to lock and to unlock.
Operation
Electric locks use magnets, solenoids, or motors to actuate the lock by either supplying or removing power. Operating the lock can be as simple as using a switch, for example an apartment intercom door release, or as complex as a biometric based access control system.
There are two basic types of locks: "preventing mechanism" or operation mechanism.
Types
Electromagnetic lock
The most basic type of electronic lock is a magnetic lock (informally called a "mag lock"). A large electro-magnet is mounted on the door frame and a corresponding armature is mounted on the door. When the magnet is powered and the door is closed, the armature is held fast to the magnet. Mag locks are simple to install and are very attack-resistant. One drawback is that improperly installed or maintained mag locks can fall on people, and also that one must unlock the mag lock to both enter and to leave. This has caused fire marshals to impose strict rules on the use of mag locks and access control practice in general. Additionally, NFPA 101 (Standard for Life Safety and Security), as well as the ADA (Americans with Disability Act) require "no prior knowledge" and "one simple movement" to allow "free egress". This means that in an emergency, a person must be able to move to a door and immediately exit with one motion (requiring no push buttons, having another person unlock the door, reading a sign, or |
https://en.wikipedia.org/wiki/Repeat%20sign | In music, a repeat sign is a sign that indicates a section should be repeated. If the piece has one repeat sign alone, then that means to repeat from the beginning, and then continue on (or stop, if the sign appears at the end of the piece). A corresponding sign facing the other way indicates where the repeat is to begin. These are similar to the instructions da capo and dal segno.
Different endings
When a repeat calls for a different ending, numbered brackets above the bars indicate which to play the first time (1.), which to play the second time (2.), and so on if necessary. These are called "first-time bars" and "second-time bars", or "first and second endings". They are also known as "volta brackets" and although there are normally 2 volta brackets, there is no limit to how many there can be.
In Unicode
In Unicode, repeat signs are part of the Musical Symbols and they are coded as follows:
Other notation
When only standard keyboard characters are available, the punctuation marks vertical bar and colon are used to represent repeat signs: |: ... :|
In Gregorian chant, a repeat is indicated by a Roman numeral following a section. This is common particularly in a Kyrie, where the lines followed by "iii" or "iij" are to be sung three times (corresponding to the correct liturgical form).
In shape-note singing, repeat signs usually have four dots, between each line of the staff. The corresponding sign to show where the repeat is from is either the same sign reversed (if it is at the beginning of a bar), or the dots themselves (if it is in the middle of a bar). First and second endings are given with just the numbers above the corresponding bars. Repeats notated at the beginning of a verse, or given with multiple lines of text per verse, are generally required; the repeats given for most songs of the final few lines are always optional, and almost always used only for the final verse sung.
See also
Abbreviation (music)
Coda
Da capo
Dal segno
Repetition (music) |
https://en.wikipedia.org/wiki/Fermi%20acceleration | Fermi acceleration, sometimes referred to as diffusive shock acceleration (a subclass of Fermi acceleration), is the acceleration that charged particles undergo when being repeatedly reflected, usually by a magnetic mirror (see also Centrifugal mechanism of acceleration). It receives its name from physicist Enrico Fermi who first proposed the mechanism. This is thought to be the primary mechanism by which particles gain non-thermal energies in astrophysical shock waves. It plays a very important role in many astrophysical models, mainly of shocks including solar flares and supernova remnants.
There are two types of Fermi acceleration: first-order Fermi acceleration (in shocks) and second-order Fermi acceleration (in the environment of moving magnetized gas clouds). In both cases the environment has to be collisionless in order for the mechanism to be effective. This is because Fermi acceleration only applies to particles with energies exceeding the thermal energies, and frequent collisions with surrounding particles will cause severe energy loss and as a result no acceleration will occur.
First order Fermi acceleration
Shock waves typically have moving magnetic inhomogeneities both preceding and following them. Consider the case of a charged particle traveling through the shock wave (from upstream to downstream). If it encounters a moving change in the magnetic field, this can reflect it back through the shock (downstream to upstream) at increased velocity. If a similar process occurs upstream, the particle will again gain energy. These multiple reflections greatly increase its energy. The resulting energy spectrum of many particles undergoing this process (assuming that they do not influence the structure of the shock) turns out to be a power law:
where the spectral index depends, for non-relativistic shocks, only on the compression ratio of the shock.
The term "First order" comes from the fact that the energy gain per shock crossing is proportional to , |
https://en.wikipedia.org/wiki/Novikov%20conjecture | The Novikov conjecture is one of the most important unsolved problems in topology. It is named for Sergei Novikov who originally posed the conjecture in 1965.
The Novikov conjecture concerns the homotopy invariance of certain polynomials in the Pontryagin classes of a manifold, arising from the fundamental group. According to the Novikov conjecture, the higher signatures, which are certain numerical invariants of smooth manifolds, are homotopy invariants.
The conjecture has been proved for finitely generated abelian groups. It is not yet known whether the Novikov conjecture holds true for all groups. There are no known counterexamples to the conjecture.
Precise formulation of the conjecture
Let be a discrete group and its classifying space, which is an Eilenberg–MacLane space of type , and therefore unique up to homotopy equivalence as a CW complex. Let
be a continuous map from a closed oriented -dimensional manifold to , and
Novikov considered the numerical expression, found by evaluating the cohomology class in top dimension against the fundamental class , and known as a higher signature:
where is the Hirzebruch polynomial, or sometimes (less descriptively) as the -polynomial. For each , this polynomial can be expressed in the Pontryagin classes of the manifold's tangent bundle. The Novikov conjecture states that the higher signature is an invariant of the oriented homotopy type of for every such map and every such class , in other words, if is an orientation preserving homotopy equivalence, the higher signature associated to is equal to that associated to .
Connection with the Borel conjecture
The Novikov conjecture is equivalent to the rational injectivity of the assembly map in L-theory. The
Borel conjecture on the rigidity of aspherical manifolds is equivalent to the assembly map being an isomorphism. |
https://en.wikipedia.org/wiki/Toilet-related%20injuries%20and%20deaths | There have been many toilet-related injuries and deaths throughout history and in urban legends. Dr Caolan Coleman was injured while trying to defecate in private while at work. With the excitement of the event, he stood up too quickly hitting his head off a cupboard. This caused a laceration which required glue to heal the wound from the poo.
Accidental injuries
Infants and toddlers have fallen into toilet bowls and drowned. Safety devices exist to help prevent such accidents. Injuries to adults include bruised buttocks and tail bones, as well as dislocated hips from unexpectedly sitting on the toilet bowl rim because the seat is up or loose. Injuries can also be caused by pinching due to splits in plastic seats and/or by splinters from wooden seats, or if the toilet itself collapses under the weight of the user. Older high-tank cast-iron cisterns have been known to detach from the wall when the chain is pulled to flush, causing injuries to the user. The 2000 Ig Nobel Prize in Public Health was awarded to three physicians from the Glasgow Western Infirmary for a 1993 case report on wounds sustained to the buttocks due to collapsing toilets. Furthermore, injuries are frequently sustained by people who stand on toilets to reach a height, then slip and fall. There are also instances of people slipping on a wet bathroom floor or from a bath and concussing themselves on the fixture.
Toilet-related injuries are surprisingly common, with some estimates ranging as high as 40,000 in the US every year. In the past, this number would have been much higher, due to the material from which toilet paper was made. This was shown in a 1935 Northern Tissue advertisement which depicted splinter-free toilet paper. In 2012, 2.3 million toilets in the United States, and about 9,400 in Canada, were recalled due to faulty pressure-assist flush mechanisms which put users at risk of the fixture exploding.
Injuries caused by animals
There are also injuries caused by animals. Some black wi |
https://en.wikipedia.org/wiki/Nikolay%20Krylov%20%28mathematician%2C%20born%201879%29 | Nikolay Mitrofanovich Krylov (, ; – May 11, 1955) was a Russian and Soviet mathematician known for works on interpolation, non-linear mechanics, and numerical methods for solving equations of mathematical physics.
Biography
Nikolay Krylov graduated from St. Petersburg State Mining Institute in 1902. In the period from 1912 until 1917, he held the Professor position in this institute. In 1917, he went to the Crimea to become Professor at the Crimea University. He worked there until 1922 and then moved to Kyiv to become chairman of the mathematical physics department at the Ukrainian Academy of Sciences.
Nikolay Krylov was a member of the Société mathématique de France and the American Mathematical Society.
Research
Nikolay Krylov developed new methods for analysis of equations of mathematical physics, which can be used not only for proving the existence of solutions but also for their construction. Since 1932, he worked together with his student Nikolay Bogolyubov on mathematical problems of non-linear mechanics. In this period, they invented certain asymptotic methods for integration of non-linear differential equations, studied dynamical systems, and made significant contributions to the foundations of non-linear mechanics. They proved the first theorems on existence of invariant measures known as Krylov–Bogolyubov theorems, introduced the Krylov–Bogoliubov averaging method and, together with Yurii Mitropolskiy, developed the Krylov–Bogoliubov–Mitropolskiy asymptotic method for approximate solving equations of non-linear mechanics.
Doctoral students
Nikolay Bogolyubov
Publications
Nikolay Krylov published over 200 papers on analysis and mathematical physics and two monographs:
Nicolas Kryloff (1931): Les Méthodes de Solution Approchée des Problèmes de la Physique Mathématique. Paris: Gauthier-Villars [in French].
N. M. Krylov, N. N. Bogoliubov (1947): Introduction to Nonlinear Mechanics. Princeton: Princeton University Press. .
See also
Describing function
K |
https://en.wikipedia.org/wiki/Ganbare%20Goemon%21%20Karakuri%20D%C5%8Dch%C5%AB | is a video game produced by Konami. It is the second game in the Ganbare Goemon series (sometimes known in English as Mystical Ninja) and the first to be released on a video game console and home computer. It was initially released for the Family Computer on July 30, 1986 and later released for the MSX2 a year later. The Famicom version was re-released in Japan only for the Game Boy Advance under the Famicom Mini label and for the Wii, Nintendo 3DS and Wii U under the Virtual Console service. A direct sequel, Ganbare Goemon 2, was released for the Famicom on January 4, 1989.
Gameplay
The game revolves around the main character, Goemon, and his exploits. As the name suggests, his character was based on Ishikawa Goemon, the noble thief of Japanese folklore. Unlike its sequels, this game still doesn't feature the comic situation and strange characters that define the series, and Goemon is portrayed as a noble thief rather than a plain hero.
The game plays as a top view action/adventure game (similar to The Legend of Zelda) though it is separated by stages. In each level Goemon must find three passes in order to advance. Some of these passes are found in boxes, secret passages or can be bought. After finishing all the stages, the game will present the player with a new Japanese province (eight in total), but all the levels will remain the same. The ending, however, will be different.
Like the rest of the series, Goemon can be powered-up if certain items are found and/or bought, which can be lost after a few hits.
The MSX version has the option to be played in turns by two players, with the second player playing as a ninja named Nezumi Kozō, which is the basis of Goemon's sidekick Ebisumaru. In addition, unlike the Family Computer version, the game has six more provinces with completely new levels after finishing the game once. |
https://en.wikipedia.org/wiki/.NET%20My%20Services | .NET My Services (codenamed Hailstorm) is an abandoned collection of XML-based Web services by Microsoft for storing and retrieving information. NET My Services was announced on March 19, 2001 as part of Microsoft's .NET initiative and was intended to rely on what was then known as a Microsoft Passport, a single sign-in web service now referred to as a Microsoft account.
.NET My Services was a platform intended to facilitate the storage and retrieval of user-related information, such as contacts, calendar information, and e-mail messages, by allowing it to be accessed from a centralized repository across various applications and device types, including traditional desktop PCs, and mobile devices such as laptops, mobile phones, PDAs, and tablet PCs; access to this stored information would be based solely on user discretion. The technology would rely on a subscription-based business model.
Although the technology required a Microsoft Passport, it was based on cross-platform, open standard web services, including SOAP, UDDI, and WS-Discovery, which enabled interoperability with compatible systems without requiring Microsoft Windows.
After .NET My Services was announced on March 19, 2001, Microsoft intended for it to reach broad developer availability at that year's Professional Developers Conference, with a subsequent end-user release scheduled for 2002. However, due to industry concerns related to anti-competitive behavior and end-user privacy, the company ultimately abandoned the initiative before it could fully materialize.
See also
Microsoft Office XP
Smart tags
Windows Communication Foundation
WinFS |
https://en.wikipedia.org/wiki/Vafa%E2%80%93Witten%20theorem | In theoretical physics, the Vafa–Witten theorem, named after Cumrun Vafa and Edward Witten, is a theorem that shows that vector-like global symmetries (those that transform as expected under reflections) such as isospin and baryon number in vector-like gauge theories like quantum chromodynamics cannot be spontaneously broken as long as the theta angle is zero. This theorem can be proved by showing the exponential fall off of the propagator of fermions.
See also
F-theory |
https://en.wikipedia.org/wiki/Weil%27s%20conjecture%20on%20Tamagawa%20numbers | In mathematics, the Weil conjecture on Tamagawa numbers is the statement that the Tamagawa number of a simply connected simple algebraic group defined over a number field is 1. In this case, simply connected means "not having a proper algebraic covering" in the algebraic group theory sense, which is not always the topologists' meaning.
History
calculated the Tamagawa number in many cases of classical groups and observed that it is an integer in all considered cases and that it was equal to 1 in the cases when the group is simply connected. The first observation does not hold for all groups: found examples where the Tamagawa numbers are not integers. The second observation, that the Tamagawa numbers of simply connected semisimple groups seem to be 1, became known as the Weil conjecture.
Robert Langlands (1966) introduced harmonic analysis methods to show it for Chevalley groups. K. F. Lai (1980) extended the class of known cases to quasisplit reductive groups. proved it for all groups satisfying the Hasse principle, which at the time was known for all groups without E8 factors. V. I. Chernousov (1989) removed this restriction, by proving the Hasse principle for the resistant E8 case (see strong approximation in algebraic groups), thus completing the proof of Weil's conjecture. In 2011, Jacob Lurie and Dennis Gaitsgory announced a proof of the conjecture for algebraic groups over function fields over finite fields.
Applications
used the Weil conjecture to calculate the Tamagawa numbers of all semisimple algebraic groups.
For spin groups, the conjecture implies the known Smith–Minkowski–Siegel mass formula.
See also
Tamagawa number |
https://en.wikipedia.org/wiki/List%20of%20eponyms%20of%20special%20functions | This is a list of special function eponyms in mathematics, to cover the theory of special functions, the differential equations they satisfy, named differential operators of the theory (but not intended to include every mathematical eponym). Named symmetric functions, and other special polynomials, are included.
A
Niels Abel: Abel polynomials - Abelian function - Abel–Gontscharoff interpolating polynomial
Sir George Biddell Airy: Airy function
Waleed Al-Salam (1926–1996): Al-Salam polynomial - Al Salam–Carlitz polynomial - Al Salam–Chihara polynomial
C. T. Anger: Anger–Weber function
Kazuhiko Aomoto: Aomoto–Gel'fand hypergeometric function - Aomoto integral
Paul Émile Appell (1855–1930): Appell hypergeometric series, Appell polynomial, Generalized Appell polynomials
Richard Askey: Askey–Wilson polynomial, Askey–Wilson function (with James A. Wilson)
B
Ernest William Barnes: Barnes G-function
E. T. Bell: Bell polynomials
Bender–Dunne polynomial
Jacob Bernoulli: Bernoulli polynomial
Friedrich Bessel: Bessel function, Bessel–Clifford function
H. Blasius: Blasius functions
R. P. Boas, R. C. Buck: Boas–Buck polynomial
Böhmer integral
Erland Samuel Bring: Bring radical
de Bruijn function
Buchstab function
Burchnall, Chaundy: Burchnall–Chaundy polynomial
C
Leonard Carlitz: Carlitz polynomial
Arthur Cayley, Capelli: Cayley–Capelli operator
Celine's polynomial
Charlier polynomial
Pafnuty Chebyshev: Chebyshev polynomials
Elwin Bruno Christoffel, Darboux: Christoffel–Darboux relation
Cyclotomic polynomials
D
H. G. Dawson: Dawson function
Charles F. Dunkl: Dunkl operator, Jacobi–Dunkl operator, Dunkl–Cherednik operator
Dickman–de Bruijn function
E
Engel: Engel expansion
Erdélyi Artúr: Erdelyi–Kober operator
Leonhard Euler: Euler polynomial, Eulerian integral, Euler hypergeometric integral
F
V. N. Faddeeva: Faddeeva function (also known as the complex error function; see error function)
G
C. F. Gauss: Gaussian polynomial, Gaussian distribution, etc.
Leopold Bernhar |
https://en.wikipedia.org/wiki/Whittaker%20function | In mathematics, a Whittaker function is a special solution of Whittaker's equation, a modified form of the confluent hypergeometric equation introduced by to make the formulas involving the solutions more symmetric. More generally, introduced Whittaker functions of reductive groups over local fields, where the functions studied by Whittaker are essentially the case where the local field is the real numbers and the group is SL2(R).
Whittaker's equation is
It has a regular singular point at 0 and an irregular singular point at ∞.
Two solutions are given by the Whittaker functions Mκ,μ(z), Wκ,μ(z), defined in terms of Kummer's confluent hypergeometric functions M and U by
The Whittaker function is the same as those with opposite values of , in other words considered as a function of at fixed and it is even functions. When and are real, the functions give real values for real and imaginary values of . These functions of play a role in so-called Kummer spaces.
Whittaker functions appear as coefficients of certain representations of the group SL2(R), called Whittaker models. |
https://en.wikipedia.org/wiki/Degree-constrained%20spanning%20tree | In graph theory, a degree-constrained spanning tree is a spanning tree where the maximum vertex degree is limited to a certain constant k. The degree-constrained spanning tree problem is to determine whether a particular graph has such a spanning tree for a particular k.
Formal definition
Input: n-node undirected graph G(V,E); positive integer k < n.
Question: Does G have a spanning tree in which no node has degree greater than k?
NP-completeness
This problem is NP-complete . This can be shown by a reduction from the Hamiltonian path problem. It remains NP-complete even if k is fixed to a value ≥ 2. If the problem is defined as the degree must be ≤ k, the k = 2 case of degree-confined spanning tree is the Hamiltonian path problem.
Degree-constrained minimum spanning tree
On a weighted graph, a Degree-constrained minimum spanning tree (DCMST) is a degree-constrained spanning tree in which the sum of its edges has the minimum possible sum. Finding a DCMST is an NP-Hard problem.
Heuristic algorithms that can solve the problem in polynomial time have been proposed, including Genetic and Ant-Based Algorithms.
Approximation Algorithm
give an iterative polynomial time algorithm which, given a graph , returns a spanning tree with maximum degree no larger than , where is the minimum possible maximum degree over all spanning trees. Thus, if , such an algorithm will either return a spanning tree of maximum degree or . |
https://en.wikipedia.org/wiki/List%20of%20organisms%20by%20chromosome%20count | The list of organisms by chromosome count describes ploidy or numbers of chromosomes in the cells of various plants, animals, protists, and other living organisms. This number, along with the visual appearance of the chromosome, is known as the karyotype, and can be found by looking at the chromosomes through a microscope. Attention is paid to their length, the position of the centromeres, banding pattern, any differences between the sex chromosomes, and any other physical characteristics. The preparation and study of karyotypes is part of cytogenetics. |
https://en.wikipedia.org/wiki/Spatial%20frequency | In mathematics, physics, and engineering, spatial frequency is a characteristic of any structure that is periodic across position in space. The spatial frequency is a measure of how often sinusoidal components (as determined by the Fourier transform) of the structure repeat per unit of distance.
The SI unit of spatial frequency is the reciprocal metre (m-1), although cycles per meter (c/m) is also common. In image-processing applications, spatial frequency is often expressed in units of cycles per millimeter (c/mm) or also line pairs per millimeter (LP/mm).
In wave propagation, the spatial frequency is also known as wavenumber. Ordinary wavenumber is defined as the reciprocal of wavelength and is commonly denoted by or sometimes :
Angular wavenumber , expressed in radian per metre (rad/m), is related to ordinary wavenumber and wavelength by
Visual perception
In the study of visual perception, sinusoidal gratings are frequently used to probe the capabilities of the visual system, such as contrast sensitivity. In these stimuli, spatial frequency is expressed as the number of cycles per degree of visual angle. Sine-wave gratings also differ from one another in amplitude (the magnitude of difference in intensity between light and dark stripes), orientation, and phase.
Spatial-frequency theory
The spatial-frequency theory refers to the theory that the visual cortex operates on a code of spatial frequency, not on the code of straight edges and lines hypothesised by Hubel and Wiesel on the basis of early experiments on V1 neurons in the cat. In support of this theory is the experimental observation that the visual cortex neurons respond even more robustly to sine-wave gratings that are placed at specific angles in their receptive fields than they do to edges or bars. Most neurons in the primary visual cortex respond best when a sine-wave grating of a particular frequency is presented at a particular angle in a particular location in the visual field. (However, a |
https://en.wikipedia.org/wiki/Cascading%20gauge%20theory | In theoretical physics, a cascading gauge theory is a gauge theory whose coupling rapidly changes with the scale in such a way that Seiberg duality must be applied many times.
Igor Klebanov and Matthew Strassler studied this kind of N=1 gauge theory in the context of the AdS-CFT correspondence, which is dual to the warped deformed conifold.
See also
Ultraviolet fixed point |
https://en.wikipedia.org/wiki/Point%20groups%20in%20two%20dimensions | In geometry, a two-dimensional point group or rosette group is a group of geometric symmetries (isometries) that keep at least one point fixed in a plane. Every such group is a subgroup of the orthogonal group O(2), including O(2) itself. Its elements are rotations and reflections, and every such group containing only rotations is a subgroup of the special orthogonal group SO(2), including SO(2) itself. That group is isomorphic to R/Z and the first unitary group, U(1), a group also known as the circle group.
The two-dimensional point groups are important as a basis for the axial three-dimensional point groups, with the addition of reflections in the axial coordinate. They are also important in symmetries of organisms, like starfish and jellyfish, and organism parts, like flowers.
Discrete groups
There are two families of discrete two-dimensional point groups, and they are specified with parameter n, which is the order of the group of the rotations in the group.
Intl refers to Hermann–Mauguin notation or international notation, often used in crystallography. In the infinite limit, these groups become the one-dimensional line groups.
If a group is a symmetry of a two-dimensional lattice or grid, then the crystallographic restriction theorem restricts the value of n to 1, 2, 3, 4, and 6 for both families. There are thus 10 two-dimensional crystallographic point groups:
C1, C2, C3, C4, C6,
D1, D2, D3, D4, D6
The groups may be constructed as follows:
Cn. Generated by an element also called Cn, which corresponds to a rotation by angle 2π/n. Its elements are E (the identity), Cn, Cn2, ..., Cnn−1, corresponding to rotation angles 0, 2π/n, 4π/n, ..., 2(n − 1)π/n.
Dn. Generated by element Cn and reflection σ. Its elements are the elements of group Cn, with elements σ, Cnσ, Cn2σ, ..., Cnn−1σ added. These additional ones correspond to reflections across lines with orientation angles 0, π/n, 2π/n, ..., (n − 1)π/n. Dn is thus a semidirect product of Cn and the group (E, |
https://en.wikipedia.org/wiki/Berezinian | In mathematics and theoretical physics, the Berezinian or superdeterminant is a generalization of the determinant to the case of supermatrices. The name is for Felix Berezin. The Berezinian plays a role analogous to the determinant when considering coordinate changes for integration on a supermanifold.
Definition
The Berezinian is uniquely determined by two defining properties:
where str(X) denotes the supertrace of X. Unlike the classical determinant, the Berezinian is defined only for invertible supermatrices.
The simplest case to consider is the Berezinian of a supermatrix with entries in a field K. Such supermatrices represent linear transformations of a super vector space over K. A particular even supermatrix is a block matrix of the form
Such a matrix is invertible if and only if both A and D are invertible matrices over K. The Berezinian of X is given by
For a motivation of the negative exponent see the substitution formula in the odd case.
More generally, consider matrices with entries in a supercommutative algebra R. An even supermatrix is then of the form
where A and D have even entries and B and C have odd entries. Such a matrix is invertible if and only if both A and D are invertible in the commutative ring R0 (the even subalgebra of R). In this case the Berezinian is given by
or, equivalently, by
These formulas are well-defined since we are only taking determinants of matrices whose entries are in the commutative ring R0. The matrix
is known as the Schur complement of A relative to
An odd matrix X can only be invertible if the number of even dimensions equals the number of odd dimensions. In this case, invertibility of X is equivalent to the invertibility of JX, where
Then the Berezinian of X is defined as
Properties
The Berezinian of is always a unit in the ring R0.
where denotes the supertranspose of .
Berezinian module
The determinant of an endomorphism of a free module M can be defined as the induced action on the 1-dimensi |
https://en.wikipedia.org/wiki/Hamiltonian%20fluid%20mechanics | Hamiltonian fluid mechanics is the application of Hamiltonian methods to fluid mechanics. Note that this formalism only applies to nondissipative fluids.
Irrotational barotropic flow
Take the simple example of a barotropic, inviscid vorticity-free fluid.
Then, the conjugate fields are the mass density field ρ and the velocity potential φ. The Poisson bracket is given by
and the Hamiltonian by:
where e is the internal energy density, as a function of ρ.
For this barotropic flow, the internal energy is related to the pressure p by:
where an apostrophe ('), denotes differentiation with respect to ρ.
This Hamiltonian structure gives rise to the following two equations of motion:
where is the velocity and is vorticity-free. The second equation leads to the Euler equations:
after exploiting the fact that the vorticity is zero:
As fluid dynamics is described by non-canonical dynamics, which possess an infinite amount of Casimir invariants, an alternative formulation of Hamiltonian formulation of fluid dynamics can be introduced through the use of Nambu mechanics
See also
Luke's variational principle
Hamiltonian field theory
Notes |
https://en.wikipedia.org/wiki/IR/UV%20mixing | In theoretical physics, it is usually possible to organize physical phenomena according to the energy scale or distance scale. The theory of renormalization group is based on this paradigm. The short-distance, ultraviolet (UV) physics does not directly affect qualitative features of the long-distance, infrared (IR) physics, and vice versa.
This separation of scales holds in quantum field theory. However, in its generalizations such as noncommutative field theory and quantum gravity—string theory in particular—it is expected that interrelations between UV and IR physics start to emerge. In many cases, these interrelations, UV/IR mixing, may be demonstrated explicitly.
Longer, technical description can be found here
See also
Hierarchy problem
Cutoff
Quantum gravity |
https://en.wikipedia.org/wiki/Massive%20gravity | In theoretical physics, massive gravity is a theory of gravity that modifies general relativity by endowing the graviton with a nonzero mass. In the classical theory, this means that gravitational waves obey a massive wave equation and hence travel at speeds below the speed of light.
Background
Massive gravity has a long and winding history, dating back to the 1930s when Wolfgang Pauli and Markus Fierz first developed a theory of a massive spin-2 field propagating on a flat spacetime background. It was later realized in the 1970s that theories of a massive graviton suffered from dangerous pathologies, including a ghost mode and a discontinuity with general relativity in the limit where the graviton mass goes to zero. While solutions to these problems had existed for some time in three spacetime dimensions, they were not solved in four dimensions and higher until the work of Claudia de Rham, Gregory Gabadadze, and Andrew Tolley (dRGT model) in 2010.
One of the very early massive gravity theories was constructed in 1965 by Ogievetsky and Polubarinov (OP). Despite the fact that the OP model coincides with the ghost-free massive gravity models rediscovered in dRGT, the OP model has been almost unknown among contemporary physicists who work on massive gravity, perhaps because the strategy followed in that model was quite different from what is generally adopted at present. Massive dual gravity to the OP model can be obtained by coupling the dual graviton field to the curl of its own energy-momentum tensor. Since the mixed symmetric field strength of dual gravity is comparable to the totally symmetric extrinsic curvature tensor of the Galileons theory, the effective Lagrangian of the dual model in 4-D can be obtained from the Faddeev–LeVerrier recursion, which is similar to that of Galileon theory up to the terms containing polynomials of the trace of the field strength. This is also manifested in the dual formulation of Galileon theory.
The fact that general relativi |
https://en.wikipedia.org/wiki/Composite%20gravity | In theoretical physics, composite gravity refers to models that attempted to derive general relativity in a framework where the graviton is constructed as a composite bound state of more elementary particles, usually fermions. A theorem by Steven Weinberg and Edward Witten shows that this is not possible in Lorentz covariant theories: massless particles with spin greater than one are forbidden. The AdS/CFT correspondence may be viewed as a loophole in their argument. However, in this case not only the graviton is emergent; a whole spacetime dimension is emergent, too.
See also
Weinberg–Witten theorem |
https://en.wikipedia.org/wiki/Victorian%20Web | The Victorian Web is a hypertext project derived from hypermedia environments, Intermedia and Storyspace, that anticipated the World Wide Web. Initially created between 1988 and 1990 with 1,500 documents, it has grown to over 128,500 items in July 2023. In contrast to archives and web-based libraries, the Victorian Web presents its images and documents, including entire books, as nodes in a network of complex connections. It emphasizes links rather than the searches.
In 2020 victorianweb.org became a 501(3)c non-profit corporation. The Victorian Web Foundation’s Board of Directors are Jacqueline Banerjee (President and Secretary); Noah M. Landow (Treasurer); Diane Josefowicz (Board Member); and Simon Cooke (Board Member).
The Victorian Web has many contributors, but unlike wikis, it is edited. Originally conceived in 1987 as a means of helping scholars and students in see connections between different fields, the site has expanded in its scope and vision. For example, commentary on the works of Charles Dickens is linked to his life and to contemporary social and political history, drama, religion, book illustration, and economics. Translations of this and earlier versions: Italian, Japanese, Korean, Spanish.
The Victorian Web incorporates primary and secondary texts (including book reviews) in the areas of economics, literature, philosophy, religion, political and social history, science, technology, and the visual arts. The visual arts section ranges widely over painting, photography, book design and illustration, sculpture, and the decorative arts, including ceramics, furniture, stained glass and metalwork. Jewelry, textiles, and costume are amongst other topics discussed and illustrated on its website. Awards indicate that it is particularly strong in literature, painting, architecture, sculpture, book illustration, history and religion.
History
The 1,500 or so documents that constitute its kernel were created in 1988–90 by its former webmaster and editor- |
https://en.wikipedia.org/wiki/Four-tensor | In physics, specifically for special relativity and general relativity, a four-tensor is an abbreviation for a tensor in a four-dimensional spacetime.
Generalities
General four-tensors are usually written in tensor index notation as
with the indices taking integer values from 0 to 3, with 0 for the timelike components and 1, 2, 3 for spacelike components. There are n contravariant indices and m covariant indices.
In special and general relativity, many four-tensors of interest are first order (four-vectors) or second order, but higher-order tensors occur. Examples are listed next.
In special relativity, the vector basis can be restricted to being orthonormal, in which case all four-tensors transform under Lorentz transformations. In general relativity, more general coordinate transformations are necessary since such a restriction is not in general possible.
Examples
First-order tensors
In special relativity, one of the simplest non-trivial examples of a four-tensor is the four-displacement
a four-tensor with contravariant rank 1 and covariant rank 0. Four-tensors of this kind are usually known as four-vectors. Here the component x0 = ct gives the displacement of a body in time (coordinate time t is multiplied by the speed of light c so that x0 has dimensions of length). The remaining components of the four-displacement form the spatial displacement vector x = (x1, x2, x3).
The four-momentum for massive or massless particles is
combining its energy (divided by c) p0 = E/c and 3-momentum p = (p1, p2, p3).
For a particle with invariant mass , also known as rest mass, four momentum is defined by
with the proper time of the particle.
The relativistic mass is with Lorentz factor
Second-order tensors
The Minkowski metric tensor with an orthonormal basis for the (−+++) convention is
used for calculating the line element and raising and lowering indices. The above applies to Cartesian coordinates. In general relativity, the metric tensor is given by much m |
https://en.wikipedia.org/wiki/Torsion%20%28mechanics%29 | In the field of solid mechanics, torsion is the twisting of an object due to an applied torque. Torsion is expressed in either the pascal (Pa), an SI unit for newtons per square metre, or in pounds per square inch (psi) while torque is expressed in newton metres (N·m) or foot-pound force (ft·lbf). In sections perpendicular to the torque axis, the resultant shear stress in this section is perpendicular to the radius.
In non-circular cross-sections, twisting is accompanied by a distortion called warping, in which transverse sections do not remain plane. For shafts of uniform cross-section unrestrained against warping, the torsion is:
where:
T is the applied torque or moment of torsion in Nm.
(tau) is the maximum shear stress at the outer surface
JT is the torsion constant for the section. For circular rods, and tubes with constant wall thickness, it is equal to the polar moment of inertia of the section, but for other shapes, or split sections, it can be much less. For more accuracy, finite element analysis (FEA) is the best method. Other calculation methods include membrane analogy and shear flow approximation.
r is the perpendicular distance between the rotational axis and the farthest point in the section (at the outer surface).
ℓ is the length of the object to or over which the torque is being applied.
φ (phi) is the angle of twist in radians.
G is the shear modulus, also called the modulus of rigidity, and is usually given in gigapascals (GPa), lbf/in2 (psi), or lbf/ft2 or in ISO units N/mm2.
The product JTG is called the torsional rigidity wT.
Properties
The shear stress at a point within a shaft is:
Note that the highest shear stress occurs on the surface of the shaft, where the radius is maximum. High stresses at the surface may be compounded by stress concentrations such as rough spots. Thus, shafts for use in high torsion are polished to a fine surface finish to reduce the maximum stress in the shaft and increase their service life.
The angle o |
https://en.wikipedia.org/wiki/Torsion%20of%20a%20curve | In the differential geometry of curves in three dimensions, the torsion of a curve measures how sharply it is twisting out of the osculating plane. Taken together, the curvature and the torsion of a space curve are analogous to the curvature of a plane curve. For example, they are coefficients in the system of differential equations for the Frenet frame given by the Frenet–Serret formulas.
Definition
Let be a space curve parametrized by arc length and with the unit tangent vector . If the curvature of at a certain point is not zero then the principal normal vector and the binormal vector at that point are the unit vectors
respectively, where the prime denotes the derivative of the vector with respect to the parameter . The torsion measures the speed of rotation of the binormal vector at the given point. It is found from the equation
which means
As , this is equivalent to .
Remark: The derivative of the binormal vector is perpendicular to both the binormal and the tangent, hence it has to be proportional to the principal normal vector. The negative sign is simply a matter of convention: it is a byproduct of the historical development of the subject.
Geometric relevance: The torsion measures the turnaround of the binormal vector. The larger the torsion is, the faster the binormal vector rotates around the axis given by the tangent vector (see graphical illustrations). In the animated figure the rotation of the binormal vector is clearly visible at the peaks of the torsion function.
Properties
A plane curve with non-vanishing curvature has zero torsion at all points. Conversely, if the torsion of a regular curve with non-vanishing curvature is identically zero, then this curve belongs to a fixed plane.
The curvature and the torsion of a helix are constant. Conversely, any space curve whose curvature and torsion are both constant and non-zero is a helix. The torsion is positive for a right-handed helix and is negative for a left-handed on |
https://en.wikipedia.org/wiki/Torsion%20%28algebra%29 | In mathematics, specifically in ring theory, a torsion element is an element of a module that yields zero when multiplied by some non-zero-divisor of the ring. The torsion submodule of a module is the submodule formed by the torsion elements. A torsion module is a module that equals its torsion submodule. A module is torsion-free if its torsion submodule comprises only the zero element.
This terminology is more commonly used for modules over a domain, that is, when the regular elements of the ring are all its nonzero elements.
This terminology applies to abelian groups (with "module" and "submodule" replaced by "group" and "subgroup"). This is allowed by the fact that the abelian groups are the modules over the ring of integers (in fact, this is the origin of the terminology, that has been introduced for abelian groups before being generalized to modules).
In the case of groups that are noncommutative, a torsion element is an element of finite order. Contrary to the commutative case, the torsion elements do not form a subgroup, in general.
Definition
An element m of a module M over a ring R is called a torsion element of the module if there exists a regular element r of the ring (an element that is neither a left nor a right zero divisor) that annihilates m, i.e.,
In an integral domain (a commutative ring without zero divisors), every non-zero element is regular, so a torsion element of a module over an integral domain is one annihilated by a non-zero element of the integral domain. Some authors use this as the definition of a torsion element, but this definition does not work well over more general rings.
A module M over a ring R is called a torsion module if all its elements are torsion elements, and torsion-free if zero is the only torsion element. If the ring R is commutative then the set of all torsion elements forms a submodule of M, called the torsion submodule of M, sometimes denoted T(M). If R is not commutative, T(M) may or may not be a submodule. I |
https://en.wikipedia.org/wiki/List%20of%20topology%20topics | In mathematics, topology (from the Greek words , and ) is concerned with the properties of a geometric object that are preserved under continuous deformations, such as stretching, twisting, crumpling and bending, but not tearing or gluing.
A topological space is a set endowed with a structure, called a topology, which allows defining continuous deformation of subspaces, and, more generally, all kinds of continuity. Euclidean spaces, and, more generally, metric spaces are examples of a topological space, as any distance or metric defines a topology. The deformations that are considered in topology are homeomorphisms and homotopies. A property that is invariant under such deformations is a topological property. Basic examples of topological properties are: the dimension, which allows distinguishing between a line and a surface; compactness, which allows distinguishing between a line and a circle; connectedness, which allows distinguishing a circle from two non-intersecting circles.
The ideas underlying topology go back to Gottfried Leibniz, who in the 17th century envisioned the and . Leonhard Euler's Seven Bridges of Königsberg problem and polyhedron formula are arguably the field's first theorems. The term topology was introduced by Johann Benedict Listing in the 19th century, although it was not until the first decades of the 20th century that the idea of a topological space was developed.
This is a list of topology topics. See also:
Topology glossary
List of topologies
List of general topology topics
List of geometric topology topics
List of algebraic topology topics
List of topological invariants (topological properties)
Publications in topology
Topology and physics
Quantum topology
Topological defect
Topological entropy in physics
Topological order
Topological quantum field theory
Topological quantum number
Topological string theory
Topology of the universe
Topology and dynamical systems
Milnor–Thurston kneading theory
Topological conjugacy
Topological |
https://en.wikipedia.org/wiki/Phenotypic%20plasticity | Phenotypic plasticity refers to some of the changes in an organism's behavior, morphology and physiology in response to a unique environment. Fundamental to the way in which organisms cope with environmental variation, phenotypic plasticity encompasses all types of environmentally induced changes (e.g. morphological, physiological, behavioural, phenological) that may or may not be permanent throughout an individual's lifespan.
The term was originally used to describe developmental effects on morphological characters, but is now more broadly used to describe all phenotypic responses to environmental change, such as acclimation (acclimatization), as well as learning. The special case when differences in environment induce discrete phenotypes is termed polyphenism.
Generally, phenotypic plasticity is more important for immobile organisms (e.g. plants) than mobile organisms (e.g. most animals), as mobile organisms can often move away from unfavourable environments. Nevertheless, mobile organisms also have at least some degree of plasticity in at least some aspects of the phenotype.
One mobile organism with substantial phenotypic plasticity is Acyrthosiphon pisum of the aphid family, which exhibits the ability to interchange between asexual and sexual reproduction, as well as growing wings between generations when plants become too populated.
Water fleas (Daphnia magna) have shown both phenotypic plasticity and the ability to genetically evolve to deal with the heat stress of warmer, urban pond waters.
Examples
Plants
Phenotypic plasticity in plants includes the timing of transition from vegetative to reproductive growth stage, the allocation of more resources to the roots in soils that contain low concentrations of nutrients, the size of the seeds an individual produces depending on the environment, and the alteration of leaf shape, size, and thickness. Leaves are particularly plastic, and their growth may be altered by light levels. Leaves grown in the light ten |
https://en.wikipedia.org/wiki/Central%20field%20approximation | In atomic physics, the central field approximation for many-electron atoms takes the combined electric fields of the nucleus and all the electrons acting on any of the electrons to be radial and to be the same for all the electrons in the atom. That is, every electron sees an identical potential that is only a function of its distance from the nucleus.
This facilitates an approximate analytical solution to the eigenvalue problem for the Hamiltonian operator. |
https://en.wikipedia.org/wiki/Sound%20Blaster%20X-Fi | Sound Blaster X-Fi is a lineup of sound cards in Creative Technology's Sound Blaster series.
History
The series was launched in August 2005 as a lineup of PCI sound cards, which served as the introduction for their X-Fi audio processing chip, with models ranging from XtremeMusic (lower end), to Platinum, Fatal1ty FPS, and Elite Pro (top of the range).
The top-end Elite Pro model was aimed at musicians, bundled with the X-Fi external I/O box (offering phono with preamp inputs for turntables, high-impedance input for guitars, inch mic input, headphone output, line-in, and full size MIDI I/O, as well as optical and RCA Coaxial digital inputs and outputs), and remote control.
The Platinum and Fatal1ty FPS models both offer a front-panel drive-bay control unit and remote control, while the base model was supplied without any such accessories.
All but the top model claimed 109 dB signal-to-noise ratio, while the Elite Pro model uses a higher-end DAC, with 116 dB claimed. The bottom two models feature 2 MB onboard X-RAM, while the top models offer 64 MB of X-RAM, designed for use in games to store sound samples for improved gaming performance. Launch reviews did not support Creative's claims of higher performance, however, with even the top-end 64 MB equipped model falling slightly behind the older Audigy cards.
October 2006 saw a minor rebranding: the X-Fi XtremeMusic edition, which was in fact a highly capable gaming card, as it offers hardware decoding and EAX support, was replaced with the XtremeGamer model. The revised model featured half-width PCB, non-gold-plated connectors, optical out instead of the digital out and digital I/O module jack, and lacked the connector for users wishing to purchase a separate X-Fi I/O box. Functionality is otherwise the same.
The market segment occupied by the XtremeMusic was moved downwards, with the introduction of the (cheaper) 'Xtreme Audio' and 'Xtreme Audio Notebook' products, which, despite the "X-Fi" label, are the only |
https://en.wikipedia.org/wiki/Daihachiro%20Sato | was a Japanese mathematician who was awarded the Lester R. Ford Award in 1976 for his work in number theory, specifically on his work in the Diophantine representation of prime numbers. His doctoral supervisor at the University of California, Los Angeles was Ernst G. Straus.
Biography
Sato was an only child born in Fujinomiya, Shizuoka, Japan on June 1, 1932. While still attending high school, Sato published his first mathematics research paper, which led to his acceptance at the Tokyo University of Education. There, Sato earned a B.S. in theoretical physics, a popular academic field at the time due to the recent Nobel Prize in Physics awarded in 1949 to Hideki Yukawa. Later, in 1965, Shin'ichirō Tomonaga, one of Dr. Sato's professors at this university, was also awarded a Nobel Prize in Physics.
Following his undergraduate degree in Japan, he switched his studies to mathematics, earning a M.Sc. and a Ph.D. from UCLA, and eventually became tenured at the University of Saskatchewan, Regina campus in Regina, Saskatchewan, Canada. Following his retirement in 1997 he was granted the position Professor Emeritus at the University of Regina which is what the Regina campus became in 1974. Subsequently, he further taught at the Tokyo University of Social Welfare from 2000 until 2006, after which he returned to Canada. He died at Ladner, British Columbia on May 28, 2008.
Sato's interests included integer valued entire functions, generalized interpolation by analytic functions, prime representing functions, and function theory. It is in the field of prime representing functions that Sato co-authored a paper with James P. Jones, Hideo Wada, and Douglas Wiens entitled "Diophantine Representation of the Set of Prime Numbers", which won them the Lester R. Ford Award in Mathematics in 1976.
Publications
—Dissertation: Ph.D.
— MathSciNet review: 0409325 |
https://en.wikipedia.org/wiki/Sternohyoid%20muscle | The sternohyoid muscle is a bilaterally paired, long, thin, narrow strap muscle of the anterior neck. It is one of the infrahyoid muscles. It is innervated by the ansa cervicalis. It acts to depress the hyoid bone.
Structure
The sternohyoid muscle is one of the paired strap muscles of the infrahyoid muscles.
The muscle is directed superomedially from its origin to its insertion. The two muscles are separated by a considerable interval inferiorly, but usually converge by their mid-point and remain proximal until their superior insertion.
Origin
It arises from the posterior aspect of the medial end (sternal extremity of the clavicle, the posterior sternoclavicular ligament, and (the superoposterior portion of) the manubrium of sternum.
It inserts onto the inferior border of the body of hyoid bone.
Nerve supply
The sternohyoid muscle receives motor innervation from branches of the ansa cervicalis (which are ultimately derived from cervical spinal nerves C1-C3).
Relations
The muscle is situated lateral to the trachea.
Variations
The muscle may be absent, doubled, exhibit a clavicular slip (the cleidohyoideus), or interrupted by a tendinous intersection; it sometimes presents a transverse tendinous inscription just distal to its origin.
Actions/movements
The muscle depresses the hyoid bone when the bone is in an elevated position.
Function
The sternohyoid muscle performs a number of functions:
aids in speech (it is primarily involved in modulation with speech volume rather than intonation).
contributes to movements of the head and neck.
Additional images |
https://en.wikipedia.org/wiki/Sternothyroid%20muscle | The sternothyroid muscle (or sternothyroideus) is an infrahyoid muscle of the neck. It acts to depress the hyoid bone.
Structure
The two muscles are in contact with each other proximally (close their origin), but diverge distally (towards their insertions).
Origin
The sternothyroid arises from the posterior surface of the manubrium of the sternum (inferior to the origin of the sternohyoid muscle), and the posterior margin of the first costal cartilage.
Insertion
It inserts onto the oblique line of the lamina of thyroid cartilage.
Innervation
The sternothyroid muscle receives motor innervation from branches of the ansa cervicalis (ultimately derived from cervical spinal nerves C1-C3).
Relations
The sternothyroid muscle is shorter and wider than the sternohyoid muscle and is situated deep to and partially medial to it.
Variations
The muscle may be absent or doubled. It may issue accessory slips to the thyrohyoid muscle, inferior pharyngeal constrictor muscle, or the carotid sheath.
Actions/movements
The sternothyroid muscle depresses the hyoid bone. When the hyoid bone is fixed, it instead elevates the larynx (producing an increased voice pitch).
Clinical significance
The upward extension of a thyroid swelling (goitre) is prevented by the attachment of the sternothyroid to the thyroid cartilage. A goitre can therefore only grow to the front, back or middle but no higher.
Additional images |
https://en.wikipedia.org/wiki/Thyrohyoid%20muscle | The thyrohyoid muscle is a small skeletal muscle of the neck. Above, it attaches onto the greater cornu of the hyoid bone; below, it attaches onto the oblique line of the thyroid cartilage. It is innervated by fibres derived from the cervical spinal nerve 1 that run with the hypoglossal nerve (CN XII) to reach this muscle. The thyrohyoid muscle depresses the hyoid bone and elevates the larynx during swallowing. By controlling the position and shape of the larynx, it aids in making sound.
Structure
The thyrohyoid muscle is a small, broad and short muscle. It is quadrilateral in shape. It may be considered a superior-ward continuation of sternothyroid muscle.
It belongs to the infrahyoid muscles group and the outer laryngeal muscle group.
Attachments
Its superior attachment is the inferior border of the greater cornu of the hyoid bone and adjacent portions of the body of hyoid bone.
Its inferior attachment is the oblique line of the thyroid cartilage (alongside the sternothyroid muscle).
Innervation
The thyrohyoid muscle is innervated (along with the geniohyoid muscle) by a branch of the cervical plexus - the nerve to thyrohyoid muscle (thyrohyoid branch of ansa cervicalis) - which is formed by fibres of the cervical spinal nerve 1 (C1) (and - according to some sources - cervical spinal nerve 2 as well) that join and travel with the hypoglossal nerve (CN XII) before splitting away from it distal to the superior root of ansa cervicalis. The thyrohyoid muscle is the only infrahyoid muscle that is not innervated via the ansa cervicalis.
Blood supply
The muscle is provided with arterial blood by branches of the superior thyroid artery, and of the lingual artery.
Relations
The thyrohyoid muscle forms the inferior boundary of the carotid triangle. It is situated deep to (beneath) the (depending upon the source) superior portion of/superior belly of the sternohyoid muscle, and the superior portion of the omohyoid muscle.
Function
The thyrohyoid muscle depresses |
https://en.wikipedia.org/wiki/Longus%20capitis%20muscle | The longus capitis muscle (Latin for long muscle of the head, alternatively rectus capitis anticus major), is broad and thick above, narrow below, and arises by four tendinous slips, from the anterior tubercles of the transverse processes of the third, fourth, fifth, and sixth cervical vertebræ, and ascends, converging toward its fellow of the opposite side, to be inserted into the inferior surface of the basilar part of the occipital bone.
It is innervated by a branch of cervical plexus.
Longus capitis has several actions:
acting unilaterally, to:
flex the head and neck laterally
rotate the head ipsilaterally
acting bilaterally:
flex the head and neck
Additional images |
https://en.wikipedia.org/wiki/Longus%20colli%20muscle | The longus colli muscle (Latin for long muscle of the neck) is a muscle of the human body.
The longus colli is situated on the anterior surface of the vertebral column, between the atlas and the third thoracic vertebra.
It is broad in the middle, narrow and pointed at either end, and consists of three portions, a superior oblique, an inferior oblique, and a vertical.
The superior oblique portion arises from the anterior tubercles of the transverse processes of the third, fourth, and fifth cervical vertebrae and, ascending obliquely with a medial inclination, is inserted by a narrow tendon into the tubercle on the anterior arch of the atlas.
The inferior oblique portion, the smallest part of the muscle, arises from the front of the bodies of the first two or three thoracic vertebrae; and, ascending obliquely in a lateral direction, is inserted into the anterior tubercles of the transverse processes of the fifth and sixth cervical vertebrae.
The vertical portion arises, below, from the front of the bodies of the upper three thoracic and lower three cervical vertebrae, and is inserted into the front of the bodies of the second, third, and fourth cervical vertebrae.
Clinical significance
It is commonly injured in rear end whiplash injuries, usually resulting from a car crash.
This muscle is in front of the spine and is thought by some scientists that it may cause some whiplash patients to have an unnatural lack of curvature in the patients' neck.
Acute calcific tendinitis of the longus colli muscle can occur. This presents with acute onset of neck pain, stiffness, dysphagia and odynophagia, and must be distinguished from retropharyngeal abscess and other sinister conditions. Imaging diagnosis is by CT or MRI, demonstrating calcification in the muscle in addition to retropharyngeal oedema. Treatment is supportive, with non-steroidal anti-inflammatory drugs.
Additional Images |
https://en.wikipedia.org/wiki/Rectus%20capitis%20anterior%20muscle | The rectus capitis anterior (rectus capitis anticus minor) is a short, flat muscle, situated immediately behind the upper part of the Longus capitis.
It arises from the anterior surface of the lateral mass of the atlas, and from the root of its transverse process, and passing obliquely upward and medialward, is inserted into the inferior surface of the basilar part of the occipital bone immediately in front of the foramen magnum.
action: aids in flexion of the head and the neck;
nerve supply: C1, C2.
Additional images |
https://en.wikipedia.org/wiki/Rectus%20capitis%20lateralis%20muscle | The rectus capitis lateralis, a short, flat muscle, arises from the upper surface of the transverse process of the atlas, and is inserted into the under surface of the jugular process of the occipital bone.
Additional images
See also
Atlanto-occipital joint
Rectus capitis posterior major muscle
Rectus capitis posterior minor muscle
Rectus capitis anterior muscle |
https://en.wikipedia.org/wiki/Multifidus%20muscle | The multifidus (multifidus spinae : pl. multifidi ) muscle consists of a number of fleshy and tendinous fasciculi, which fill up the groove on either side of the spinous processes of the vertebrae, from the sacrum to the axis. While very thin, the multifidus muscle plays an important role in stabilizing the joints within the spine. The multifidus is one of the transversospinales.
Located just superficially to the spine itself, the multifidus muscle spans three joint segments and works to stabilize these joints at each level.
The stiffness and stability makes each vertebra work more effectively, and reduces the degeneration of the joint structures caused by friction from normal physical activity.
These fasciculi arise:
in the sacral region: from the back of the sacrum, as low as the fourth sacral foramen, from the aponeurosis of origin of the sacrospinalis, from the medial surface of the posterior superior iliac spine, and from the posterior sacroiliac ligaments.
in the lumbar region: from all the mamillary processes.
in the thoracic region: from all the transverse processes.
in the cervical region: from the articular processes of the lower four vertebrae.
Each fasciculus, passing obliquely upward and medially, is inserted into the whole length of the spinous process of one of the vertebræ above.
These fasciculi vary in length: the most superficial, the longest, pass from one vertebra to the third or fourth above; those next in order run from one vertebra to the second or third above; while the deepest connect two adjacent vertebrae.
The multifidus lies deep relative to the spinal erectors, transverse abdominis, abdominal internal oblique muscle and abdominal external oblique muscle.
Atrophy and association with low back pain
Dysfunction in the lumbar multifidus muscles is strongly associated with low back pain. The dysfunction can be caused by inhibition of pain by the spine. The dysfunction frequently persists even after the pain has disappeared. Such |
https://en.wikipedia.org/wiki/Rotatores%20muscles | The rotatores muscles (rotatores spinae muscles) lie beneath the multifidus and are present in all spinal regions but are most prominent in the thoracic region; they are eleven in number on either side.
Each muscle is small and somewhat quadrilateral in form; it arises from the superior and posterior part of the transverse process, and is inserted into the lower border and lateral surface of the lamina of the vertebra above, the fibers extending as far as the root of the spinous process.
The first thoracic rotatores muscle is found between the first and second thoracic vertebrae; the last, between the eleventh and twelfth. Sometimes the number of these muscles is diminished by the absence of one or more from the upper or lower end. The Rotatores muscles have a high density of proprioceptors and have been implicated in postural control.
See also
Multifidus muscle |
https://en.wikipedia.org/wiki/Semispinalis%20muscles | The semispinalis muscles are a group of three muscles belonging to the transversospinales. These are the semispinalis capitis, the semispinalis cervicis and the semispinalis thoracis.
The semispinalis capitis (complexus) is situated at the upper and back part of the neck, deep to the splenius, and medial to the longissimus cervicis and longissimus capitis. It arises by a series of tendons from the tips of the transverse processes of the upper six or seven thoracic and the seventh cervical vertebrae, and from the articular processes of the three cervical vertebrae above this (C4-C6).
The tendons, uniting, form a broad muscle, which passes upward, and is inserted between the superior and inferior nuchal lines of the occipital bone. It lies deep to the trapezius muscle and can be palpated as a firm round muscle mass just lateral to the cervical spinous processes.
The semispinalis cervicis (or semispinalis colli), arises by a series of tendinous and fleshy fibers from the transverse processes of the upper five or six thoracic vertebrae, and is inserted into the cervical spinous processes, from the axis to the fifth cervical vertebrae inclusive. The semispinalis cervicis is thicker than the semispinalis thoracis. The fasciculus connected with the axis is the largest, and is chiefly muscular in structure.
The semispinalis thoracis (or semispinalis dorsi) muscle consists of thin, narrow, fleshy fasciculi, interposed between tendons of considerable length. It arises by a series of small tendons from the transverse processes of the sixth to the tenth thoracic vertebrae, and is inserted, by tendons, into the spinous processes of the upper four thoracic and lower two cervical vertebrae.
The semispinalis muscles are innervated by the dorsal rami of the cervical spinal nerves.
See also
List of muscles of the human body
Additional images |
https://en.wikipedia.org/wiki/Splenius%20capitis%20muscle | The splenius capitis () () is a broad, straplike muscle in the back of the neck. It pulls on the base of the skull from the vertebrae in the neck and upper thorax. It is involved in movements such as shaking the head.
Structure
It arises from the lower half of the nuchal ligament, from the spinous process of the seventh cervical vertebra, and from the spinous processes of the upper three or four thoracic vertebrae.
The fibers of the muscle are directed upward and laterally and are inserted, under cover of the sternocleidomastoideus, into the mastoid process of the temporal bone, and into the rough surface on the occipital bone just below the lateral third of the superior nuchal line. The splenius capitis is deep to sternocleidomastoideus at the mastoid process, and to the trapezius for its lower portion. It is one of the muscles that forms the floor of the posterior triangle of the neck.
The splenius capitis muscle is innervated by the posterior ramus of spinal nerves C3 and C4.
Function
The splenius capitis muscle is a prime mover for head extension. The splenius capitis can also allow lateral flexion and rotation of the cervical spine.
Additional images
See also |
https://en.wikipedia.org/wiki/Splenius%20cervicis%20muscle | The splenius cervicis () (also known as the splenius colli, ) is a muscle in the back of the neck. It arises by a narrow tendinous band from the spinous processes of the third to the sixth thoracic vertebrae; it is inserted, by tendinous fasciculi, into the posterior tubercles of the transverse processes of the upper two or three cervical vertebrae.
Its name is based on the Greek word σπληνίον, splenion (meaning a bandage) and the Latin word cervix (meaning a neck). The word collum also refers to the neck in Latin.
The function of the splenius cervicis muscle is extension of the cervical spine, rotation to the ipsilateral side and lateral flexion to the ipsilateral side.
Additional images |
https://en.wikipedia.org/wiki/Rectus%20capitis%20posterior%20major%20muscle | The rectus capitis posterior major (or rectus capitis posticus major) is a muscle in the upper back part of the neck. It is one of the suboccipital muscles. Its inferior attachment is at the spinous process of the axis (first cervical vertebra); its superior attachment is onto the outer surface of the occipital bone on and around the side part of the inferior nuchal line. The muscle is innervated by the suboccipital nerve (the posterior ramus of cervical spinal nerve C1). The muscle acts to extend the head and rorate the head to its side.
Anatomy
The rectus capitis posterior major muscle is one of the suboccipital muscles. It forms the superomedial boundary of the suboccipital triangle.
The muscle extends obliquely superiolaterally from its inferior attachment to its superior attachment. It becomes broader superiorly.
Attachments
Its inferior attachment is (via a pointed tendon) at (the external asepct of) the (bifid) spinous process of the axis (cervical vertebra C1).
Its superior attachment is at (the lateral portion of) the inferior nuchal line and the surface of the occipital bone just inferior to this line.
Innervation
The muscle receives motor innervation from the suboccipital nerve (the posterior ramus of cervical spinal nerve C1).
Relations
Superiorly, as the two muscles diverge laterally, they create between them a triangular space in which parts of the two recti capitis posteriores minores muscles are exposed.
Actions/movements
The muscle extends the head and (acting together with the obliquus capitis inferior muscle) ipsilaterally rotates the head.
Function
Its main actions are to extend and rotate the atlanto-occipital joint.
Research
A soft tissue connection bridging from the rectus capitis posterior major to the cervical dura mater was described in 2011. Various clinical manifestations may be linked to this anatomical relationship. It has also been postulated that this connection serves as a monitor of dural tension along with the rectu |
https://en.wikipedia.org/wiki/Rectus%20capitis%20posterior%20minor%20muscle | The rectus capitis posterior minor (or rectus capitis posticus minor) is a muscle in the upper back part of the neck. It is one of the suboccipital muscles. Its inferior attachment is at the posterior arch of atlas; its superior attachment is onto the occipital bone at and below the inferior nuchal line. The muscle is innervated by the suboccipital nerve (the posterior ramus of first cervical spinal nerve). The muscle acts as a weak extensor of the head.
Anatomy
The rectus capitis posterior major muscle is one of the suboccipital muscles.
The muscle extends vertically superior-ward from its inferiro attachment to its superior attachment. The muscle becomes broader superiorly.
Attachments
The inferior attachment is (by a narrow tendon) onto the posterior tubercle of the posterior arch of atlas.
Its superior attachment is onto to the medial portion of the inferior nuchal line and the external surface of the occipital bone inferior to it (between this line superiorly and the foramen magnum inferiorly).
The muscle usually also additionally attaches onto the posterior atlantooccipital membrane (which is in turn attached onto adjacent dura mater of the spinal canal).
Innervation
The muscle receives motor innervation from the suboccipital nerve (the posterior ramus of cervical spinal nerve C1).
Variation
The muscle of either side may be doubled (along its length).
Actions/movements
The muscle is a weak extensor of the head.
The synergists are the rectus capitis posterior major and the obliquus capitis superior.
Research
Role in headache
Connective tissue bridges were noted at the atlanto-occipital joint between the rectus capitis posterior minor (RCPm) muscle and the dorsal spinal dura. Similar connective tissue connections of the rectus capitis posterior major have been reported recently as well. The perpendicular arrangement of these fibers appears to restrict dural movement toward the spinal cord. The ligamentum nuchae was found to be continuous with th |
https://en.wikipedia.org/wiki/External%20intercostal%20muscles | The external intercostal muscles, or external intercostals (Intercostales externi) are eleven in number on both sides.
Structure
The muscles extend from the tubercles of the ribs behind, to the cartilages of the ribs in front, where they end in thin membranes, the external intercostal membranes, which are continued forward to the sternum.
These muscles work in unison when inhalation occurs. The internal intercostal muscles relax while the external muscles contract causing the expansion of the chest cavity and an influx of air into the lungs.
Each arises from the lower border of a rib, and is inserted into the upper border of the rib below. In the two lower spaces they extend to the ends of the cartilages, and in the upper two or three spaces they do not quite reach the ends of the ribs.
They are thicker than the internal intercostals, and their fibers are directed obliquely downward and laterally on the back of the thorax, and downward, forward, and medially on the front.
Variations
Continuation with the external oblique or serratus anterior: A supracostalis muscle, from the anterior end of the first rib down to the second, third or fourth ribs occasionally occurs.
Additional images
See also
Inhalation |
https://en.wikipedia.org/wiki/Internal%20intercostal%20muscles | The internal intercostal muscles (intercostales interni) are a group of skeletal muscles located between the ribs. They are eleven in number on either side. They commence anteriorly at the sternum, in the intercostal spaces between the cartilages of the true ribs, and at the anterior extremities of the cartilages of the false ribs, and extend backward as far as the angles of the ribs, hence they are continued to the vertebral column by thin aponeuroses, the posterior intercostal membranes. They pull the sternum and ribs upward and inward.
Structure
Their fibers are also directed obliquely, but pass in a direction opposite to those of the external intercostal muscles. The internal intercostal muscles originate from the costal groove of the rib and insert into the superior aspect of the rib below in a direction perpendicular to the external intercostal muscles. It is this arrangement that allows these muscles to facilitate exhalation.
For the most part, they are muscles of exhalation. In exhalation the interosseous portions of the internal intercostal muscles, (the part of the muscle that is between the bone portion of the superior and inferior ribs), depresses and retracts the ribs, compressing the thoracic cavity and expelling air. The internal intercostals, however, are only used in forceful exhalation such as coughing or during exercise and not in relaxed breathing. The external intercostal muscles, and the intercartilaginous part of the internal intercostal muscles, (the part of the muscle that lies between the cartilage portion of the superior and inferior ribs), are used in inspiration, by aiding in elevating the ribs and expanding the thoracic cavity.
Additional images |
https://en.wikipedia.org/wiki/Serratus%20posterior%20inferior%20muscle | The serratus posterior inferior muscle, also known as the posterior serratus muscle, is a muscle of the human body.
Structure
The muscle is situated at the junction of the thoracic and lumbar regions. It has an irregularly quadrilateral form, broader than the serratus posterior superior muscle, and separated from it by a wide interval.
It arises by a thin aponeurosis from the spinous processes of the lower two thoracic and upper two or three lumbar vertebrae.
Passing obliquely upward and lateralward, it becomes fleshy, and divides into four flat digitations. These are inserted into the inferior borders of the lower four ribs, a little beyond their angles.
The thin aponeurosis of origin is intimately blended with the thoracolumbar fascia, and aponeurosis of the latissimus dorsi muscle.
Function
The serratus posterior inferior draws the lower ribs backward and downward to assist in rotation and extension of the trunk. This movement of the ribs may also contribute to inhalation and forced expiration of air from the lungs.
Additional images
See also
Serratus anterior muscle
Serratus posterior superior muscle |
https://en.wikipedia.org/wiki/Serratus%20posterior%20superior%20muscle | The serratus posterior superior muscle is a thin, quadrilateral muscle. It is situated at the upper back part of the thorax, deep to the rhomboid muscles.
Structure
The serratus posterior superior muscle arises by an aponeurosis from the lower part of the nuchal ligament, from the spinous processes of C7, T1, T2, and sometimes T3, and from the supraspinal ligament. It is inserted, by four fleshy digitations into the upper borders of the second, third, fourth, and fifth ribs past the angle of the rib.
Function
The serratus posterior superior muscle elevates the second to fifth ribs. This aids deep respiration.
Additional images
See also
Serratus anterior muscle
Serratus posterior inferior muscle |
https://en.wikipedia.org/wiki/Subcostalis%20muscle | The Subcostales (singular: subcostalis) (Infracostales) consist of muscular and aponeurotic fasciculi, which are usually well-developed only in the lower part of the thorax; each originates from the inner surface of one rib, and is inserted into the inner surface of the second or third rib below, near its angle.
Their fibers run in the same direction as those of the Intercostales interni.
Depresses the ribs to assist in expiration. |
https://en.wikipedia.org/wiki/Abdominal%20external%20oblique%20muscle | The abdominal external oblique muscle (also external oblique muscle, or exterior oblique) is the largest and outermost of the three flat abdominal muscles of the lateral anterior abdomen.
Structure
The external oblique is situated on the lateral and anterior parts of the abdomen. It is broad, thin, and irregularly quadrilateral, its muscular portion occupying the side, its aponeurosis the anterior wall of the abdomen. In most humans (especially females), the oblique is not visible, due to subcutaneous fat deposits and the small size of the muscle.
It arises from eight fleshy digitations, each from the external surfaces and inferior borders of the fifth to twelfth ribs (lower eight ribs). These digitations are arranged in an oblique line which runs inferiorly and anteriorly, with the upper digitations being attached close to the cartilages of the corresponding ribs, the lowest to the apex of the cartilage of the last rib, the intermediate ones to the ribs at some distance from their cartilages.
The five superior serrations increase in size from above downward, and are received between corresponding processes of the serratus anterior muscle; the three lower ones diminish in size from above downward and receive between them corresponding processes from the latissimus dorsi. From these attachments the fleshy fibers proceed in various directions. Its posterior fibers from the ribs to the iliac crest form a free posterior border.
Those from the lowest ribs pass nearly vertically downward, and are inserted into the anterior half of the outer lip of the iliac crest; the middle and upper fibers, directed downward (inferiorly) and forward (anteriorly), become aponeurotic at approximately the midclavicular line and form the anterior layer of the rectus sheath. This aponeurosis formed from fibres from either side of the external oblique decussates at the linea alba.
The aponeurosis of the external oblique muscle forms the inguinal ligament. The muscle also contributes to |
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