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https://en.wikipedia.org/wiki/List%20of%20space%20groups | There are 230 space groups in three dimensions, given by a number index, and a full name in Hermann–Mauguin notation, and a short name (international short symbol). The long names are given with spaces for readability. The groups each have a point group of the unit cell.
Symbols
In Hermann–Mauguin notation, space groups are named by a symbol combining the point group identifier with the uppercase letters describing the lattice type. Translations within the lattice in the form of screw axes and glide planes are also noted, giving a complete crystallographic space group.
These are the Bravais lattices in three dimensions:
P primitive
I body centered (from the German Innenzentriert)
F face centered (from the German Flächenzentriert)
A centered on A faces only
B centered on B faces only
C centered on C faces only
R rhombohedral
A reflection plane m within the point groups can be replaced by a glide plane, labeled as a, b, or c depending on which axis the glide is along. There is also the n glide, which is a glide along the half of a diagonal of a face, and the d glide, which is along a quarter of either a face or space diagonal of the unit cell. The d glide is often called the diamond glide plane as it features in the diamond structure.
, , or : glide translation along half the lattice vector of this face
: glide translation along half the diagonal of this face
: glide planes with translation along a quarter of a face diagonal
: two glides with the same glide plane and translation along two (different) half-lattice vectors.
A gyration point can be replaced by a screw axis denoted by a number, n, where the angle of rotation is . The degree of translation is then added as a subscript showing how far along the axis the translation is, as a portion of the parallel lattice vector. For example, 21 is a 180° (twofold) rotation followed by a translation of ½ of the lattice vector. 31 is a 120° (threefold) rotation followed by a translation of ⅓ of the lattice vector. |
https://en.wikipedia.org/wiki/List%20of%20character%20tables%20for%20chemically%20important%203D%20point%20groups | This lists the character tables for the more common molecular point groups used in the study of molecular symmetry. These tables are based on the group-theoretical treatment of the symmetry operations present in common molecules, and are useful in molecular spectroscopy and quantum chemistry. Information regarding the use of the tables, as well as more extensive lists of them, can be found in the references.
Notation
For each non-linear group, the tables give the most standard notation of the finite group isomorphic to the point group, followed by the order of the group (number of invariant symmetry operations). The finite group notation used is: Zn: cyclic group of order n, Dn: dihedral group isomorphic to the symmetry group of an n–sided regular polygon, Sn: symmetric group on n letters, and An: alternating group on n letters.
The character tables then follow for all groups. The rows of the character tables correspond to the irreducible representations of the group, with their conventional names, known as Mulliken symbols, in the left margin. The naming conventions are as follows:
A and B are singly degenerate representations, with the former transforming symmetrically around the principal axis of the group, and the latter asymmetrically. E, T, G, H, ... are doubly, triply, quadruply, quintuply, ... degenerate representations.
g and u subscripts denote symmetry and antisymmetry, respectively, with respect to a center of inversion. Subscripts "1" and "2" denote symmetry and antisymmetry, respectively, with respect to a nonprincipal rotation axis. Higher numbers denote additional representations with such asymmetry.
Single prime ( ' ) and double prime ( '' ) superscripts denote symmetry and antisymmetry, respectively, with respect to a horizontal mirror plane σh, one perpendicular to the principal rotation axis.
All but the two rightmost columns correspond to the symmetry operations which are invariant in the group. In the case of sets of similar op |
https://en.wikipedia.org/wiki/Generalised%20Hough%20transform | The generalized Hough transform (GHT), introduced by Dana H. Ballard in 1981, is the modification of the Hough transform using the principle of template matching. The Hough transform was initially developed to detect analytically defined shapes (e.g., line, circle, ellipse etc.). In these cases, we have knowledge of the shape and aim to find out its location and orientation in the image. This modification enables the Hough transform to be used to detect an arbitrary object described with its model.
The problem of finding the object (described with a model) in an image can be solved by finding the model's position in the image. With the generalized Hough transform, the problem of finding the model's position is transformed to a problem of finding the transformation's parameter that maps the model into the image. Given the value of the transformation's parameter, the position of the model in the image can be determined.
The original implementation of the GHT used edge information to define a mapping from orientation of an edge point to a reference point of the shape. In the case of a binary image where pixels can be either black or white, every black pixel of the image can be a black pixel of the desired pattern thus creating a locus of reference points in the Hough space. Every pixel of the image votes for its corresponding reference points. The maximum points of the Hough space indicate possible reference points of the pattern in the image. This maximum can be found by scanning the Hough space or by solving a relaxed set of equations, each of them corresponding to a black pixel.
History
Merlin and Farber showed how to use a Hough algorithm when the desired curves could not be described analytically. It was a precursor to Ballard's algorithm that was restricted to translation and did not account for rotation and scale changes.
The Merlin-Farber algorithm is impractical for real image data as in an image with many edge pixels, it finds many false positives due to |
https://en.wikipedia.org/wiki/TSX-32 | TSX-32 has been a general purpose 32-bit multi-user multitasking operating system for x86 architecture platform, with a command line user interface. It is compatible with some 16-bit DOS applications and supports file systems FAT16 and FAT32. It was developed by S&H Computer Systems, and has been available since 1989.
DEC-oriented columnist Kevin G. Barkes noted that TSX-32 is "not a port of the PDP-11 TSX-Plus" and that it runs
well on 386, 486 and Pentium-based systems. He reported a limitation: since it supports the MS/DOS (FAT) file system, filenames are DOS's 8+3.
TSX-Plus
An earlier non-DEC operating system, also from S&H, was named TSX-Plus. Released in 1980, TSX-Plus was the successor to TSX, released in 1976.
The strength of TSX-Plus is to simultaneously provide to multiple users the services of DEC's single-user RT-11. Depending on which PDP-11 model and the amount of memory, the system could support a minimum of 12 users (14-18 users on a 2Mb 11/73, depending on workload). A productivity feature called "virtual lines" "allows a single user to control several tasks from a single terminal."
History
S&H wrote the original TSX because "Spending $25K on a computer that could only support one user bugged" (founder Harry Sanders); the outcome was the initial four-user TSX in 1976.
For TSX-32, they said in an interview, "We started with a clean sheet of paper" rather than starting with a "port."
As of 2021, it appears to be defunct.
VAX
The company's product line was ported/expanded for the VAX line.
See also
Multiuser DOS Federation |
https://en.wikipedia.org/wiki/Mathematics%20in%20Education%20and%20Industry | MEI (Mathematics in Education and Industry) is an independent educational charity and curriculum development body for mathematics education in the United Kingdom. Income generated through its work is used to support the teaching and learning of mathematics.
History
MEI was founded in 1963 with a grant from the Schools & Industry Committee of the Mathematical Association. In 1965 it produced its first exam, Additional Mathematics, then produced an A level course two years later. MEI's A-level exams were the first to include probability.
It was incorporated as a company on 18 October 1996.
Structure
Although independent, MEI works in partnership with many organisations, including the UK Government. MEI is a registered charity with a board of directors and a small professional staff.
Qualifications
GCE AS/A level Mathematics, Further Mathematics and Further Mathematics (Additional) (Published by OCR)
AS Level Statistics
GCSE Mathematics
Foundations of Advanced Mathematics (FAM) – a freestanding course
Introduction to Quantitative Methods (in association with OCR)
OCR MEI Level 3 Core Maths Qualifications (Level 3 Certificate in Quantitative Reasoning and Level 3 Certificate in Quantitative Problem Solving)
Competitions
MEI organises an annual online competition called Ritangle for teams of students of A level Mathematics, the International Baccalaureate and Scottish Highers. Questions are posted on the Integral website, with correct answers releasing a clue for the final question. |
https://en.wikipedia.org/wiki/AOS/VS%20II | AOS/VS II is a discontinued operating system for the Data General 32-bit MV/Eclipse computers.
Overview
The AOS/VS II operating system was released in 1988 and was originally to be simply rev 8.00 of the AOS/VS operating system. However, it introduced a new file system which was not compatible with the original AOS and AOS/VS file system and also contained new features like Access control list (ACL) groups. Since some customers did not want to upgrade to the new file system, or invest in new hardware, Data General agreed to continue bug-fix support of an “immortal” revision of AOS/VS, which became known colloquially as AOS/VS “Classic”, while new development would proceed as AOS/VS II, with revision numbers rolled back to 1.00.
Both VS-Classic (rev 7.7x) and VS-II (rev. 3.2x) were updated to survive the Year 2000 problem, although by this time both were obsolescent.
Among the other new features that were part of AOS/VS II were a full TCP/IP stack, NFS support, expanded kernel address space using ring-1 and a logical disk-level user data cache. /VS (classic) had a file system metadata cache, but no user data cache.
See also
Data General RDOS
Proprietary operating systems
Data General |
https://en.wikipedia.org/wiki/Slitless%20spectroscopy | Slitless spectroscopy is spectroscopy done without a small slit to allow only light from a small region to be diffracted. It works best in sparsely populated fields, as it spreads each point source out into its spectrum, and crowded fields can be too confused to be useful for some applications. It also faces the problem that for extended sources, nearby emission lines will overlap. This technique is a basic form of snapshot hyperspectral imaging. Slitless spectroscopy is used for astronomical surveys and in fields, such as solar physics, where time evolution is important. Both types of application benefit from higher speed operation of a slitless spectrograph: conventional spectrographs require multiple exposures, scanning the slit across the target, to acquire a complete spectral image, while a slitless spectrograph can capture a complete image plane in one exposure.
The Crossley telescope utilized a slitless spectrograph that was originally employed by Nicholas Mayall.
The Henry Draper Catalogue, published 1924, contains stellar classifications for hundreds of thousands of stars, based on spectra taken with the objective prism method at Harvard College Observatory. The work of classification was led initially by Williamina Fleming and later by Annie Jump Cannon, with contributions from many other female astronomers including Florence Cushman.
Slitless spectrographs encounter an unusual form of specular reflection at the grating, which leads to anisotropic image distortion called Littrow expansion or compression. The distortion occurs because the normal rules of specular reflection don't apply to reflective gratings operated far from the non-dispersive reflection angle.
See also
Fine Guidance Sensor and Near Infrared Imager and Slitless Spectrograph (JWST component)
Echelle grating |
https://en.wikipedia.org/wiki/Internationalization%20Tag%20Set | The Internationalization Tag Set (ITS) is a set of attributes and elements designed to provide internationalization and localization support in XML documents.
The ITS specification identifies concepts (called "ITS data categories") which are important for internationalization and localization. It also defines implementation of these concepts through a set of elements and attributes grouped in the ITS namespace. XML developers can use this namespace to integrate internationalization features directly into their own XML schemas and documents.
Overview
ITS v1.0 includes seven data categories:
Translate: Defines what parts of a document are translatable or not.
Localization Note: Provides alerts, hints, instructions, or other information to help the localizers or the translators.
Terminology: Indicates which parts of the documents are terms and optionally points to information about these terms.
Directionality: Indicates what type of display directionality should be applied to parts of the document.
Ruby: Indicates what parts of the document should be displayed as ruby text. (Ruby is a short run of text alongside a base text, typically used in East Asian documents to indicate pronunciation or to provide a brief annotation).
Language Information: Identifies the language of the different parts of the document.
Elements Within Text: Indicates how elements should be treated with regard to linguistic segmentation.
The vocabulary is designed to address two different aspects: First by providing markup usable directly in the XML documents. Second, by offering a way to indicate if there are parts of a given markup that correspond to some of the ITS data categories and should be treated as such by ITS processors.
ITS applies to both new document types as well as existing ones. It also applies to both markups without any internationalization features as well documents already supporting internationalization or localization-related functions.
ITS can be specified usin |
https://en.wikipedia.org/wiki/Piezomagnetism | Piezomagnetism is a phenomenon observed in some antiferromagnetic and ferrimagnetic crystals. It is characterized by a linear coupling between the system's magnetic polarization and mechanical strain. In a piezomagnetic material, one may induce a spontaneous magnetic moment by applying mechanical stress, or a physical deformation by applying a magnetic field.
Piezomagnetism differs from the related property of magnetostriction; if an applied magnetic field is reversed in direction, the strain produced changes signs. Additionally, a non-zero piezomagnetic moment can be produced by mechanical strain alone, at zero fields, which is not true of magnetostriction. According to the Institute of Electrical and Electronics Engineers (IEEE): "Piezomagnetism is the linear magneto-mechanical effect analogous to the linear electromechanical effect of piezoelectricity. Similarly, magnetostriction and electrostriction are analogous second-order effects. These higher-order effects can be represented as effectively first-order when variations in the system parameters are small compared with the initial values of the parameters".
The piezomagnetic effect is made possible by an absence of certain symmetry elements in a crystal structure; specifically, symmetry under time reversal forbids the property.
The first experimental observation of piezomagnetism was made in 1960, in the fluorides of cobalt and manganese.
The strongest piezomagnet known is uranium dioxide, with magnetoelastic memory switching at magnetic fields near 180,000 Oe at temperatures below 30 kelvins. |
https://en.wikipedia.org/wiki/Airline%20reservations%20system | Airline reservation systems (ARS) are systems that allow an airline to sell their inventory (seats). It contains information on schedules and fares and contains a database of reservations (or passenger name records) and of tickets issued (if applicable). ARSs are part of passenger service systems (PSS), which are applications supporting the direct contact with the passenger.
ARS eventually evolved into the computer reservations system (CRS). A computer reservation system is used for the reservations of a particular airline and interfaces with a global distribution system (GDS) which supports travel agencies and other distribution channels in making reservations for most major airlines in a single system.
Overview
Airline reservation systems incorporate airline schedules, fare tariffs, passenger reservations and ticket records. An airline's direct distribution works within their own reservation system, as well as pushing out information to the GDS. The second type of direct distribution channel are consumers who use the internet or mobile applications to make their own reservations. Travel agencies and other indirect distribution channels access the same GDS as those accessed by the airline reservation systems, and all messaging is transmitted by a standardized messaging system that functions on two types of messaging that transmit on SITA's high level network (HLN). These messaging types are called Type A [usually EDIFACT format] for real time interactive communication and Type B [TTY] for informational and booking type of messages. Message construction standards set by IATA and ICAO, are global, and apply to more than air transportation. Since airline reservation systems are business critical applications, and they are functionally quite complex, the operation of an in-house airline reservation system is relatively expensive.
Prior to deregulation, airlines owned their own reservation systems with travel agents subscribing to them. Today, the GDS are run by ind |
https://en.wikipedia.org/wiki/Pan-American%20Journal%20of%20Aquatic%20Sciences | The Pan-American Journal of Aquatic Sciences is a peer-reviewed open access scientific journal. It covers research on all aspects of the aquatic sciences. Articles are published in English, Spanish, or Portuguese.
Abstracting and indexing
The journal is abstracted and is indexed in Aquatic Sciences and Fisheries Abstracts and Scopus. |
https://en.wikipedia.org/wiki/Traumatic%20insemination | Traumatic insemination, also known as hypodermic insemination, is the mating practice in some species of invertebrates in which the male pierces the female's abdomen with his aedeagus and injects his sperm through the wound into her abdominal cavity (hemocoel). The sperm diffuses through the female's hemolymph, reaching the ovaries and resulting in fertilization.
The process is detrimental to the female's health. It creates an open wound which impairs the female until it heals, and is susceptible to infection. The injection of sperm and ejaculatory fluids into the hemocoel can also trigger an immune reaction in the female. Bed bugs, which reproduce solely by traumatic insemination, have evolved a pair of sperm-receptacles, known as the spermalege. It has been suggested that the spermalege reduces the direct damage to the female bed bug during traumatic insemination. However experiments found no conclusive evidence for that hypothesis; as of 2003, the preferred explanation for that organ is hygienic protection against bacteria.
The evolutionary origins of traumatic insemination are disputed. Although it evolved independently in many invertebrate species, traumatic insemination is most highly adapted and thoroughly studied in bed bugs, particularly Cimex lectularius. Traumatic insemination is not limited to male-female couplings, or even couplings of the same species. Both homosexual and inter-species traumatic inseminations have been observed.
Mechanics
In humans and other vertebrates, blood and lymph circulate in two different systems, the circulatory system and lymphatic system, which are enclosed by systems of capillaries, veins, arteries, and nodes. This is known as a closed circulatory system. Insects, however, have an open circulatory system in which blood and lymph circulate unenclosed, and mix to form a substance called hemolymph. All organs of the insect are bathed in hemolymph, which provides oxygen and nutrients to all of the insect's organs.
Follo |
https://en.wikipedia.org/wiki/Antigenic%20escape | Antigenic escape, immune escape, immune evasion or escape mutation occurs when the immune system of a host, especially of a human being, is unable to respond to an infectious agent: the host's immune system is no longer able to recognize and eliminate a pathogen, such as a virus. This process can occur in a number of different ways of both a genetic and an environmental nature. Such mechanisms include homologous recombination, and manipulation and resistance of the host's immune responses.
Different antigens are able to escape through a variety of mechanisms. For example, the African trypanosome parasites are able to clear the host's antibodies, as well as resist lysis and inhibit parts of the innate immune response. A bacteria, Bordetella pertussis, is able to escape the immune response by inhibiting neutrophils and macrophages from invading the infection site early on. One cause of antigenic escape is that a pathogen's epitopes (the binding sites for immune cells) become too similar to a person's naturally occurring MHC-1 epitopes, resulting in the immune system becoming unable to distinguish the infection from self-cells.
Antigenic escape is not only crucial for the host's natural immune response, but also for the resistance against vaccinations. The problem of antigenic escape has greatly deterred the process of creating new vaccines. Because vaccines generally cover a small ratio of strains of one virus, the recombination of antigenic DNA that lead to diverse pathogens allows these invaders to resist even newly developed vaccinations. Some antigens may even target pathways different from those the vaccine had originally intended to target. Recent research on many vaccines, including the malaria vaccine, has focused on how to anticipate this diversity and create vaccinations that can cover a broader spectrum of antigenic variation. On 12 May 2021, scientists reported to The United States Congress of the continuing threat of COVID-19 variants and COVID-19 escap |
https://en.wikipedia.org/wiki/Page%20attribute%20table | The page attribute table (PAT) is a processor supplementary capability extension to the page table format of certain x86 and x86-64 microprocessors. Like memory type range registers (MTRRs), they allow for fine-grained control over how areas of memory are cached, and are a companion feature to the MTRRs.
Unlike MTRRs, which provide the ability to manipulate the behavior of caching for a limited number of fixed physical address ranges, Page Attribute Tables allow for such behavior to be specified on a per-page basis, greatly increasing the ability of the operating system to select the most efficient behavior for any given task.
Processors
The PAT is available on Pentium III and newer CPUs, and on non-Intel CPUs.
See also
Write-combining |
https://en.wikipedia.org/wiki/Autonetics%20Recomp%20II | The Autonetics RECOMP II was a computer first introduced in 1958. It was made by the Autonetics division of North American Aviation.
It was attached to a desk that housed the input/output devices. Its desk integration made it a hands-on small system intended for the scientific and engineering computing market. The computer weighed about , including input-output.
Architecture
It had a 40-bit word size, 20-bit instruction size. Memory and registers were on a fixed head disk that operated like a drum memory—4080 words on standard tracks, 16 words on fast loop tracks, registers A, B, R, X each on their own high-speed loop track, and one prerecorded read only clock track.
It had a complete set of built-in floating point operations, including square root. Floating-point values used two words, one for the exponent and one for the fraction for a total of 80 bits.
Whereas the full 40-bit word was used for data, instructions were only 20 bits long and were stored two per word. Since indexing was commonly done by modifying the address part of an instruction (say, by adding one to access the next data item in a list), such instructions always had to be in the second half-word, and the first half-word was padded with a NOP instruction. Programmers also used these NOP instructions to provide space for future inserted instructions, since the assembler did not allow for use of symbolic addresses, and the insertion of a single instruction could otherwise require rewriting a lot of code.
The machine had a bit-serial architecture.
Punched paper tape was the external storage medium. The desk also had an electronic typewriter for printed output and a keyboard integrated with the system console to allow typed input and system control. Programs written in machine code could be input to the system from the console. |
https://en.wikipedia.org/wiki/Epsilon%20calculus | In logic, Hilbert's epsilon calculus is an extension of a formal language by the epsilon operator, where the epsilon operator substitutes for quantifiers in that language as a method leading to a proof of consistency for the extended formal language. The epsilon operator and epsilon substitution method are typically applied to a first-order predicate calculus, followed by a demonstration of consistency. The epsilon-extended calculus is further extended and generalized to cover those mathematical objects, classes, and categories for which there is a desire to show consistency, building on previously-shown consistency at earlier levels.
Epsilon operator
Hilbert notation
For any formal language L, extend L by adding the epsilon operator to redefine quantification:
The intended interpretation of ϵx A is some x that satisfies A, if it exists. In other words, ϵx A returns some term t such that A(t) is true, otherwise it returns some default or arbitrary term. If more than one term can satisfy A, then any one of these terms (which make A true) can be chosen, non-deterministically. Equality is required to be defined under L, and the only rules required for L extended by the epsilon operator are modus ponens and the substitution of A(t) to replace A(x) for any term t.
Bourbaki notation
In tau-square notation from N. Bourbaki's Theory of Sets, the quantifiers are defined as follows:
where A is a relation in L, x is a variable, and juxtaposes a at the front of A, replaces all instances of x with , and links them back to . Then let Y be an assembly, (Y|x)A denotes the replacement of all variables x in A with Y.
This notation is equivalent to the Hilbert notation and is read the same. It is used by Bourbaki to define cardinal assignment since they do not use the axiom of replacement.
Defining quantifiers in this way leads to great inefficiencies. For instance, the expansion of Bourbaki's original definition of the number one, using this notation, has length approxi |
https://en.wikipedia.org/wiki/Volvelle | A volvelle or wheel chart is a type of slide chart, a paper construction with rotating parts. It is considered an early example of a paper analog computer. Volvelles have been produced to accommodate organization and calculation in many diverse subjects. Early examples of volvelles are found in the pages of astronomy books. They can be traced back to "certain Arabic treatises on humoral medicine" and to the Persian astronomer, Abu Rayhan Biruni (c. 1000), who made important contributions to the development of the volvelle.
In the twentieth century, the volvelle had many diverse uses. In Reinventing the Wheel, author Jessica Helfand introduces twentieth-century volvelles with this:
The rock band Led Zeppelin employed a volvelle in the sleeve design for the album Led Zeppelin III (1970).
Two games from the game company Infocom included volvelles inside their package as "feelies": Sorcerer (1983) and A Mind Forever Voyaging (1985). Both volvelles served to impede copying of the games, because they contained information needed to play the game.
See also
E6B
Ramon Llull
Pop-up book
Slide chart
Zairja |
https://en.wikipedia.org/wiki/Jordan%20and%20Einstein%20frames | The Lagrangian in scalar-tensor theory can be expressed in the Jordan frame in which the scalar field or some function of it multiplies the Ricci scalar, or in the Einstein frame in which Ricci scalar is not multiplied by the scalar field. There exist various transformations between these frames. Despite the fact that these frames have been around for some time there is has been debate about whether either, both, or neither frame is a 'physical' frame which can be compared to observations and experiment.
Christopher Hill and Graham Ross have shown that there exist ``gravitational contact terms" in the Jordan frame, whereby the action is modified by graviton exchange. This modification leads back to the Einstein frame as the effective theory.
Contact interactions arise in Feynman diagrams when a vertex contains a power of the exchanged momentum, , which then cancels against the Feynman propagator, , leading to a point-like interaction. This must be included as part of the effective action of the theory. When the contact term is included results for amplitudes in the Jordan frame will be equivalent to those in the Einstein frame, and
results of physical calculations in the Jordan frame that omit the contact terms will generally be incorrect. This implies that the Jordan frame action is misleading, and the Einstein frame is uniquely correct for fully representing the physics.
Equations and physical interpretation
If we perform the Weyl rescaling , then the Riemann and Ricci tensors are modified as follows.
As an example consider the transformation of a simple Scalar-tensor action with an arbitrary set of matter fields coupled minimally to the curved background
The tilde fields then correspond to quantities in the Jordan frame and the fields without the tilde correspond to fields in the Einstein frame. See that the matter action changes only in the rescaling of the metric.
The Jordan and Einstein frames are constructed to render certain parts of physical |
https://en.wikipedia.org/wiki/Banded%20knifefish | The banded knifefish (Gymnotus carapo) is a species of gymniform knifefish native to a wide range of freshwater habitats in South America. It is the most widespread species of Gymnotus, but it has frequently been confused with several relatives, including some found outside its range like the Central America G. maculosus. The English name "banded knifefish" is sometimes used for the entire genus Gymnotus instead of only the species G. carapo.
Range and habitat
This South American fish is found in the Amazon, Orinoco and Río de la Plata basins, as well as rivers in the Guianas, northeastern Brazil (only those exiting along the country's northern coast, such as Parnaíba) and northern Argentina (south to the 36th parallel south), and in Trinidad. This makes it the most widespread species of Gymnotus.
G. carapo occurs in virtually any freshwater habitat in its range, such as rivers and streams (both slow- and fast-flowing), floodplains, estuaries, swamps and lakes. However, it is not known from deep river channels. It can survive in low-oxygen habitats by breathing air with a modified swim bladder, areas affected by pollution, and for a period on land if its aquatic habitat dries out.
Appearance
G. carapo reaches up to in total length, but it rarely surpasses and depending on exact population average is . In a study where two breeding males were located one was long and the other . It is brown with an oblique banded pattern. The strength and details of this pattern varies, both individually and depending on region. There are also some morphometric variations depending on location. A review found that these were insufficient for recognizing the populations as separate species, but did recommend recognizing them as subspecies: G. c. carapo (French Guiana and Suriname), G. c. australis (Río de la Plata basin), G. c. caatingaensis (Parnaíba river basin), G. c. madeirensis (upper Madeira river basin), G. c. occidentalis (Western Amazon, and Rio Negro and Essequibo riv |
https://en.wikipedia.org/wiki/Limit%20comparison%20test | In mathematics, the limit comparison test (LCT) (in contrast with the related direct comparison test) is a method of testing for the convergence of an infinite series.
Statement
Suppose that we have two series and with for all .
Then if with , then either both series converge or both series diverge.
Proof
Because we know that for every there is a positive integer such that for all we have that , or equivalently
As we can choose to be sufficiently small such that is positive.
So and by the direct comparison test, if converges then so does .
Similarly , so if diverges, again by the direct comparison test, so does .
That is, both series converge or both series diverge.
Example
We want to determine if the series converges. For this we compare it with the convergent series
As we have that the original series also converges.
One-sided version
One can state a one-sided comparison test by using limit superior. Let for all . Then if with and converges, necessarily converges.
Example
Let and for all natural numbers . Now
does not exist, so we cannot apply the standard comparison test. However,
and since converges, the one-sided comparison test implies that converges.
Converse of the one-sided comparison test
Let for all . If diverges and converges, then necessarily
, that is,
. The essential content here is that in some sense the numbers are larger than the numbers .
Example
Let be analytic in the unit disc and have image of finite area. By Parseval's formula the area of the image of is proportional to . Moreover,
diverges. Therefore, by the converse of the comparison test, we have
, that is,
.
See also
Convergence tests
Direct comparison test |
https://en.wikipedia.org/wiki/Topological%20derivative | The topological derivative is, conceptually, a derivative of a shape functional with respect to infinitesimal changes in its topology, such as adding an infinitesimal hole or crack. When used in higher dimensions than one, the term topological gradient is also used to name the first-order term of the topological asymptotic expansion, dealing only with infinitesimal singular domain perturbations. It has applications in shape optimization, topology optimization, image processing and mechanical modeling.
Definition
Let be an open bounded domain of , with , which is subject to a nonsmooth perturbation confined in a small region of size with an arbitrary point of and a fixed domain of . Let be a characteristic function associated to the unperturbed domain and be a characteristic function associated to the perforated domain . A given shape functional associated to the topologically perturbed domain, admits the following topological asymptotic expansion:
where is the shape functional associated to the reference domain, is a positive first order correction function of and is the remainder. The function is called the topological derivative of at .
Applications
Structural mechanics
The topological derivative can be applied to shape optimization problems in structural mechanics. The topological derivative can be considered as the singular limit of the shape derivative. It is a generalization of this classical tool in shape optimization. Shape optimization concerns itself with finding an optimal shape. That is, find to minimize some scalar-valued objective function, . The topological derivative technique can be coupled with level-set method.
In 2005, the topological asymptotic expansion for the Laplace equation with respect to the insertion of a short crack inside a plane domain had been found. It allows to detect and locate cracks for a simple model problem: the steady-state heat equation with the heat flux imposed and the temperature measured on the bo |
https://en.wikipedia.org/wiki/Radio%20atmospheric%20signal | A radio atmospheric signal or sferic (sometimes also spelled "spheric") is a broadband electromagnetic impulse that occurs as a result of natural atmospheric lightning discharges. Sferics may propagate from their lightning source without major attenuation in the Earth–ionosphere waveguide, and can be received thousands of kilometres from their source. On a time-domain plot, a sferic may appear as a single high-amplitude spike in the time-domain data. On a spectrogram, a sferic appears as a vertical stripe (reflecting its broadband and impulsive nature) that may extend from a few kHz to several tens of kHz, depending on atmospheric conditions.
Sferics received from about distance or greater have their frequencies slightly offset in time, producing tweeks.
When the electromagnetic energy from a sferic escapes the Earth-ionosphere waveguide and enters the magnetosphere, it becomes dispersed by the near-Earth plasma, forming a whistler signal. Because the source of the whistler is an impulse (i.e., the sferic), a whistler may be interpreted as the impulse response of the magnetosphere (for the conditions at that particular instant).
Introduction
A lightning channel with all its branches and its electric currents behaves like a huge antenna system from which electromagnetic waves of all frequencies are radiated. Beyond a distance where luminosity is visible and thunder can be heard (typically about 10 km), these electromagnetic impulses are the only sources of direct information about thunderstorm activity on the ground. Transients electric currents during return strokes (R strokes) or intracloud strokes (K strokes) are the main sources for the generation of impulse-type electromagnetic radiation known as sferics (sometimes called atmospherics). While this impulsive radiation dominates at frequencies less than about 100 kHz, (loosely called long waves), a continuous noise component becomes increasingly important at higher frequencies. The longwave electromagnetic pro |
https://en.wikipedia.org/wiki/Less-than%20sign | The less-than sign is a mathematical symbol that denotes an inequality between two values. The widely adopted form of two equal-length strokes connecting in an acute angle at the left, , has been found in documents dated as far back as the 1560s. In mathematical writing, the less-than sign is typically placed between two values being compared and signifies that the first number is less than the second number. Examples of typical usage include and .
Since the development of computer programming languages, the less-than sign and the greater-than sign have been repurposed for a range of uses and operations.
Computing
The less-than sign, , is an original ASCII character (hex 3C, decimal 60).
Programming
In BASIC, Lisp-family languages, and C-family languages (including Java and C++), comparison operator < means "less than".
In Coldfusion, operator .lt. means "less than".
In Fortran, operator .LT. means "less than"; later versions allow <.
Shell scripts
In Bourne shell (and many other shells), operator -lt means "less than". Less-than sign is used to redirect input from a file. Less-than plus ampersand () is used to redirect from a file descriptor.
Double less-than sign
The double less-than sign, , may be used for an approximation of the much-less-than sign () or of the opening guillemet (). ASCII does not encode either of these signs, though they are both included in Unicode.
In Bash, Perl, and Ruby, operator (where "EOF" is an arbitrary string, but commonly "EOF" denoting "end of file") is used to denote the beginning of a here document.
In C and C++, operator represents a binary left shift.
In the C++ Standard Library, operator , when applied on an output stream, acts as insertion operator and performs an output operation on the stream.
In Ruby, operator acts as append operator when used between an array and the value to be appended.
In XPath the operator returns true if the left operand precedes the right operand in document order; otherwise it retu |
https://en.wikipedia.org/wiki/Greater-than%20sign | The greater-than sign is a mathematical symbol that denotes an inequality between two values. The widely adopted form of two equal-length strokes connecting in an acute angle at the right, , has been found in documents dated as far back as 1631. In mathematical writing, the greater-than sign is typically placed between two values being compared and signifies that the first number is greater than the second number. Examples of typical usage include and . The less-than sign and greater-than sign always "point" to the smaller number. Since the development of computer programming languages, the greater-than sign and the less-than sign have been repurposed for a range of uses and operations.
History
The earliest known use of the symbols and is found in (The Analytical Arts Applied to Solving Algebraic Equations) by Thomas Harriot, published posthumously in 1631. The text states " a > b a b (The sign of majority a > b indicates that a is greater than b)" and " a < b a b (The sign of minority a < b indicates that a is less than b)."
According to historian Art Johnson, while Harriot was surveying North America, he saw a Native American with a symbol that resembled the greater-than sign, in both backwards and forwards forms. Johnson says it is likely Harriot developed the two symbols from this symbol.
Usage in text markup
Angle brackets
The greater-than sign is sometimes used for an approximation of the closing angle bracket, . The proper Unicode character is . ASCII does not have angular brackets.
HTML
In HTML (and SGML and XML), the greater-than sign is used at the end of tags. The greater-than sign may be included with , while produces the greater-than or equal to sign.
E-mail and Markdown
In some early e-mail systems, the greater-than sign was used to denote quotations.
The sign is also used to denote quotations in Markdown.
Usage in programming
The 'greater-than sign' is encoded in ASCII as character hex 3E, decimal 62. The Unicode code point is , i |
https://en.wikipedia.org/wiki/Danskin%27s%20theorem | In convex analysis, Danskin's theorem is a theorem which provides information about the derivatives of a function of the form
The theorem has applications in optimization, where it sometimes is used to solve minimax problems. The original theorem given by J. M. Danskin in his 1967 monograph provides a formula for the directional derivative of the maximum of a (not necessarily convex) directionally differentiable function.
An extension to more general conditions was proven 1971 by Dimitri Bertsekas.
Statement
The following version is proven in "Nonlinear programming" (1991). Suppose is a continuous function of two arguments,
where is a compact set.
Under these conditions, Danskin's theorem provides conclusions regarding the convexity and differentiability of the function
To state these results, we define the set of maximizing points as
Danskin's theorem then provides the following results.
Convexity
is convex if is convex in for every .
Directional semi-differential
The semi-differential of in the direction , denoted is given by where is the directional derivative of the function at in the direction
Derivative
is differentiable at if consists of a single element . In this case, the derivative of (or the gradient of if is a vector) is given by
Example of no directional derivative
In the statement of Danskin, it is important to conclude semi-differentiability of and not directional-derivative as explains this simple example.
Set , we get which is semi-differentiable with but has not a directional derivative at .
Subdifferential
If is differentiable with respect to for all and if is continuous with respect to for all , then the subdifferential of is given by where indicates the convex hull operation.
Extension
The 1971 Ph.D. Thesis by Dimitri P. Bertsekas (Proposition A.22) proves a more general result, which does not require that is differentiable. Instead it assumes that is an extended real-valued closed proper |
https://en.wikipedia.org/wiki/Ferrallitisation | Ferrallitisation is the process in which rock is changed into a soil consisting of clay (kaolinite) and sesquioxides, in the form of hydrated oxides of iron and aluminium. In humid tropical areas, with consistently high temperatures and rainfall for all or most of the year, chemical weathering rapidly breaks down the rock. This at first produces clays which later also break down to form silica. The silica is removed by leaching and the sesquioxides of iron and aluminium remain, giving the characteristic red colour of many tropical soils. Ferrallitisation is the reverse of podsolisation, where silica remains and the iron and aluminum are removed. In tropical rain forests with rain throughout the year, ferrallitic soils develop. In savanna areas, with altering dry and wet climates, ferruginous soils occur.
Further reading
Biogeochemical cycle
Land management
Natural resources
Soil science |
https://en.wikipedia.org/wiki/Trigonometric%20moment%20problem | In mathematics, the trigonometric moment problem is formulated as follows: given a finite sequence {α0, ... αn }, does there exist a positive Borel measure μ on the interval [0, 2π] such that
In other words, an affirmative answer to the problems means that {α0, ... αn } are the first n + 1 Fourier coefficients of some positive Borel measure μ on [0, 2π].
Characterization
The trigonometric moment problem is solvable, that is, {αk} is a sequence of Fourier coefficients, if and only if the (n + 1) × (n + 1) Toeplitz matrix
is positive semidefinite.
The "only if" part of the claims can be verified by a direct calculation.
We sketch an argument for the converse. The positive semidefinite matrix A defines a sesquilinear product on Cn + 1, resulting in a Hilbert space
of dimensional at most n + 1, a typical element of which is an equivalence class denoted by [f]. The Toeplitz structure of A means that a "truncated" shift is a partial isometry on . More specifically, let { e0, ...en } be the standard basis of Cn + 1. Let be the subspace generated by { [e0], ... [en - 1] } and be the subspace generated by { [e1], ... [en] }. Define an operator
by
Since
V can be extended to a partial isometry acting on all of . Take a minimal unitary extension U of V, on a possibly larger space (this always exists). According to the spectral theorem, there exists a Borel measure m on the unit circle T such that for all integer k
For k = 0,...,n, the left hand side is
So
Finally, parametrize the unit circle T by eit on [0, 2π] gives
for some suitable measure μ.
Parametrization of solutions
The above discussion shows that the trigonometric moment problem has infinitely many solutions if the Toeplitz matrix A is invertible. In that case, the solutions to the problem are in bijective correspondence with minimal unitary extensions of the partial isometry V. |
https://en.wikipedia.org/wiki/Nemosis | Nemosis is a process of cell activation and death in human fibroblasts.
Initially discovered as programmed necrosis, the name nemosis, is a derivative from the Goddess Nemesis in Greek mythodology. This name was adopted for fibroblast activation based on its initiation by direct cell–cell interactions as opposed to preference for extracellular matrix (ECM) contacts. Contacts between normal diploid fibroblasts induce cell activation leading to programmed cell death, PCD. This type of PCD has features of necrosis rather than apoptosis.
Nemosis of fibroblasts, or mesenchymal cells in general, generates large amounts of mediators of inflammation, such as prostaglandins, as well as growth factors such as hepatocyte growth factor. It is thus indicated to contribute to processes like acute and chronic inflammation, and cancer. Factors secreted by nemotic fibroblasts also
break down the ECM. Such factors include several matrix metalloproteinases, and plasminogen activation. |
https://en.wikipedia.org/wiki/LandWarNet | LandWarNet (LWN) is the United States Army’s contribution to the Global Information Grid (GIG) that consists of all globally interconnected, end-to-end set of Army information capabilities, associated processes, and personnel for collecting, processing, storing, disseminating, and managing information on demand supporting warfighters, policy makers, and support personnel. It includes all Army (owned and leased) and leveraged Department of Defense (DOD)/Joint communications and computing systems and services, software (including applications), data security services, and other associated services. LandWarNet exists to enable the warfighter through Mission Command, previously described as Battle Command. Other U.S. service equivalent efforts to LandWarNet include the Navy's "FORCEnet" and the Air Force's "C2 Constellation."
Defining LandWarNet
A key document shaping the capability development (expectation) for LandWarNet is Military Operations Future Operating Capabilities. This pamphlet describes Force Operating Capabilities (FOC) desired for the U.S. Army near, mid and long term, encompassing the full spectrum of military operations, derived from analysis of joint concepts, Army Future Force concepts, and other documents developed in support of the National Military Strategy (NMS), Strategic Planning Guidance (SPG), Army Strategic Planning Guidance (ASPG), the Army Transformation Road Map (ATR), and the Army Campaign Plan (ACP).
LandWarNet is essentially the combination of the set of functional applications (for mission command, Intelligence, Logistics, etc.), transmitted over integrated network transport (space, airborne, terrestrial, infrastructure, network terminal), utilizing a common set of network services (voice, data, collaboration, mediation, storage, discovery, messaging, speed of service, quality of service, hosting, IA/Security, NetOps - information assurance, information dissemination management, and network management). LandWarNet also represents |
https://en.wikipedia.org/wiki/Neural%20tissue%20engineering | Neural tissue engineering is a specific sub-field of tissue engineering. Neural tissue engineering is primarily a search for strategies to eliminate inflammation and fibrosis upon implantation of foreign substances. Often foreign substances in the form of grafts and scaffolds are implanted to promote nerve regeneration and to repair damage caused to nerves of both the central nervous system (CNS) and peripheral nervous system (PNS) by an injury.
Introduction
The nervous system is divided into two sections: the CNS and the PNS. The CNS consists of the brain and the spinal cord, while the PNS consists of nerves that originate from the brain and spinal cord and innervate the rest of the body.
The need for neural tissue engineering arises from the difficulty of the nerve cells and neural tissues to regenerate on their own after neural damage has occurred. The PNS has some, but limited, regeneration of neural cells. Adult stem cell neurogenesis in the CNS has been found to occur in the hippocampus, the subventricular zone (SVZ), and spinal cord. CNS injuries can be caused by stroke, neurodegenerative disorders, trauma, or encephalopathy. A few methods currently being investigated to treat CNS injuries are: implanting stem cells directly into the injury site, delivering morphogens to the injury site, or growing neural tissue in vitro with neural stem or progenitor cells in a 3D scaffold. Proposed use of electrospun polymeric fibrous scaffolds for neural repair substrates dates back to at least 1986 in a NIH SBIR application from Simon. For the PNS, a severed nerve can be reconnected and reinnervated using grafts or guidance of the existing nerve through a channel.
Recent research into creating miniature cortexes, known as corticopoiesis, and brain models, known as cerebral organoids, are techniques that could further the field of neural tissue regeneration. The native cortical progenitors in corticopoiesis are neural tissues that could be effectively embedded into the |
https://en.wikipedia.org/wiki/End-of-life%20care | End-of-life care refers to health care provided in the time leading up to a person's death. End-of-life care can be provided in the hours, days, or months before a person dies and encompasses care and support for a person's mental and emotional needs, physical comfort, spiritual needs, and practical tasks.
EoLC is most commonly provided at home, in the hospital, or in a long-term care facility with care being provided by family members, nurses, social workers, physicians, and other support staff. Facilities may also have palliative or hospice care teams that will provide end-of-life care services. Decisions about end-of-life care are often informed by medical, financial and ethical considerations.
In most advanced countries, medical spending on people in the last twelve months of life makes up roughly 10% of total aggregate medical spending, while those in the last three years of life can cost up to 25%.
Medical
Advanced care planning
Advances in medicine in the last few decades have provided an increasing number of options to extend a person's life and highlighted the importance of ensuring that an individual's preferences and values for end-of-life care are honored. Advanced care planning is the process by which a person of any age is able to provide their preferences and ensure that their future medical treatment aligns with their personal values and life goals. It is typically a continual process, with ongoing discussions about a patient's current prognosis and conditions as well as conversations about medical dilemmas and options. A person will typically have these conversations with their doctor and ultimately record their preferences in an advance healthcare directive. An advance healthcare directive is a legal document that either documents a person's decisions about desired treatment or indicates who a person has entrusted to make their care decisions for them. The two main types of advanced directives are a living will and durable power of attorney f |
https://en.wikipedia.org/wiki/Animal | Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, have myocytes and are able to move, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development. As of 2022, 2.16 million living animal species have been described—of which around 1.05 million are insects, over 85,000 are molluscs, and around 65,000 are vertebrates. It has been estimated there are around 7.77 million animal species. Animals range in length from to . They have complex interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as zoology.
Most living animal species are in Bilateria, a clade whose members have a bilaterally symmetric body plan. The Bilateria include the protostomes, containing animals such as nematodes, arthropods, flatworms, annelids and molluscs, and the deuterostomes, containing the echinoderms and the chordates, the latter including the vertebrates. Life forms interpreted as early animals were present in the Ediacaran biota of the late Precambrian. Many modern animal phyla became clearly established in the fossil record as marine species during the Cambrian explosion, which began around 539 million years ago. 6,331 groups of genes common to all living animals have been identified; these may have arisen from a single common ancestor that lived 650 million years ago.
Historically, Aristotle divided animals into those with blood and those without. Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his Systema Naturae, which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa (now synonymous with Animalia) and the Protozoa, single-celled organisms no longer considered animals. In modern times, the biological classification of animals relies on ad |
https://en.wikipedia.org/wiki/Isothiazolinone | Isothiazolinone (sometimes isothiazolone) is an organic compound with the formula (CH)2SN(H)CO. A white solid, it is structurally related to isothiazole. Isothiazolone itself is of limited interest, but several of its derivatives are widely used preservatives and antimicrobials.
Synthesis
Compared to many other simple heterocycles, the discovery of isothiazolinone is fairly recent, with reports first appearing in the 1960s.
Isothiazolinones can be prepared on an industrial scale by the ring-closure of 3-mercaptopropanamides. These in turn are produced from acrylic acid via the 3-mercaptopropionic acid:
Ring-closure of the thiol-amide is typically effected by chlorination or oxidation of the 3-sulfanylpropanamide to the corresponding disulfide.
Many other routes have been developed, including addition of thiocyanate to propargyl amides.
Mechanism of action
The antimicrobial activity of isothiazolinones is attributed to their ability to inhibit life-sustaining enzymes, specifically those enzymes with thiols at their active sites. It is established that isothiazolinones form mixed disulfides upon treatment with such species.
Applications
The principal isothiazolones are:
Methylisothiazolinone (MIT, MI)
Chloromethylisothiazolinone (CMIT, CMI, MCI)
Benzisothiazolinone (BIT)
Octylisothiazolinone (OIT, OI)
Dichlorooctylisothiazolinone (DCOIT, DCOI)
Butylbenzisothiazolinone (BBIT)
These compounds all exhibit antimicrobial properties. They are used to control bacteria, fungi, and algae in cooling water systems, fuel storage tanks, pulp and paper mill water systems, oil extraction systems, wood preservation, and some paints. They are antifouling agents. They are frequently used in shampoos and other hair care products.
Chloromethylisothiazolinone (CMIT) and 2-methyl-4-isothiazolin-3-one (methylisothiazolinone or MIT) are popular derivatives. A 3:1 mixture of CMIT:MIT is sold as Kathon. Kathon is supplied as a concentrated stock solution containing from 1.5 |
https://en.wikipedia.org/wiki/Mitochondrial%20shuttle | The mitochondrial shuttles are biochemical transport systems used to transport reducing agents across the inner mitochondrial membrane. NADH as well as NAD+ cannot cross the membrane, but it can reduce another molecule like FAD and [QH2] that can cross the membrane, so that its electrons can reach the electron transport chain.
The two main systems in humans are the glycerol phosphate shuttle and the malate-aspartate shuttle. The malate/a-ketoglutarate antiporter functions move electrons while the aspartate/glutamate antiporter moves amino groups. This allows the mitochondria to receive the substrates that it needs for its functionality in an efficient manner.
Shuttles
In humans, the glycerol phosphate shuttle is primarily found in brown adipose tissue, as the conversion is less efficient, thus generating heat, which is one of the main purposes of brown fat. It is primarily found in babies, though it is present in small amounts in adults around the kidneys and on the back of our necks. The malate-aspartate shuttle is found in much of the rest of the body.
The shuttles contains a system of mechanisms used to transport metabolites that lack a protein transporter in the membrane, such as oxaloacetate.
Malate shuttle
The malate shuttle allows the mitochondria to move electrons from NADH without the consumption of metabolites and it uses two antiporters to transport metabolites and keep balance within the mitochondrial matrix and cytoplasm.
On the cytoplasmic side a transaminase enzyme is used to remove an amino group from aspartate which is converted into oxaloacetate, then malate dehydrogenase enzyme uses an NADH cofactor to reduce oxaloacetate to malate which can be transported across the membrane because of the presence of a transporter.
Once the malate is inside the matrix its converted back to oxaloacetate, which is converted to aspartate and can be transported back outside the mitochondria to allow the cycle to continue. The movement of oxaloacetate across |
https://en.wikipedia.org/wiki/Oxygen%20enhancement%20ratio | The oxygen enhancement ratio (OER) or oxygen enhancement effect in radiobiology refers to the enhancement of therapeutic or detrimental effect of ionizing radiation due to the presence of oxygen. This so-called oxygen effect is most notable when cells are exposed to an ionizing radiation dose.
The OER is traditionally defined as the ratio of radiation doses during lack of oxygen compared to no lack of oxygen for the same biological effect. This may give varying numerical values depending on the chosen biological effect. Additionally, OER may be presented in terms of hyperoxic environments and/or with altered oxygen baseline, complicating the significance of this value.
The maximum OER depends mainly on the ionizing density or LET of the radiation. Radiation with higher LET and higher relative biological effectiveness (RBE) have a lower OER in mammalian cell tissues. The value of the maximum OER varies from about 1–4. The maximum OER ranges from about 2–4 for low-LET radiations such as X-rays, beta particles and gamma rays, whereas the OER is unity for high-LET radiations such as low energy alpha particles.
Uses in medicine
The effect is used in medical physics to increase the effect of radiation therapy in oncology treatments. Additional oxygen abundance creates additional free radicals and increases the damage to the target tissue.
In solid tumors the inner parts become less oxygenated than normal tissue and up to three times higher dose is needed to achieve the same tumor control probability as in tissue with normal oxygenation.
Explanation of the Oxygen Effect
The best known explanation of the oxygen effect is the oxygen fixation hypothesis which postulates that oxygen permanently fixes radical-induced DNA damage so it becomes permanent. Recently, it has been posited that the oxygen effect involves radiation exposures of cells causing their mitochondria to produce greater amounts of reactive oxygen species.
See also
Radiation therapy
Radiobiology
Health |
https://en.wikipedia.org/wiki/Rekursiv | Rekursiv was a computer processor designed by David M. Harland in the mid-1980s at a division of hi-fi manufacturer Linn Products. It was one of the few computer architectures intended to implement object-oriented concepts directly in hardware, a form of high-level language computer architecture. The Rekursiv operated directly on objects rather than bits, nibbles, bytes and words. Virtual memory was used as a persistent object store and unusually, the processor instruction set supported recursion (hence the name).
By the time the project had delivered its first implementation, new processors like the Sun SPARC and Intel 486 had surpassed its performance, and development was abandoned in 1988.
History
The Rekursiv project started as an effort to improve the assembly line controls in Linn's factories in Glasgow, Scotland. Their lines were automated using a suite of VAX-11 systems, but these were slow and very difficult to program with the flexibility that Linn's founder, Ivor Tiefenbrun, desired. By the early 1980s, Tiefenbrun had become convinced that object-oriented programming would offer solutions to these problems.
In 1981, Tiefenbrun hired a number of programmers to write a version of the Smalltalk language for the VAX systems, borrowing some syntax from ALGOL. Known as LINGO, the system worked but ran very slowly on the VAX platform. Tiefenbrun concluded the solution to the performance issue was not to improve the language on the VAX but instead produce an entirely new CPU dedicated specifically to running object programs.
In 1984, Tiefenbrun formed the wholly owned subsidiary Linn Smart Computing under the direction of University of Strathclyde professor David Harland and the Rekursiv project was born. The first version of the system emerged in 1988. A small number of prototype VMEbus boards, called Hades, comprising these four chips plus 80 MB of RAM were produced. These were intended for installation in a host system such as a Sun-3 workstation. Although |
https://en.wikipedia.org/wiki/Addition-subtraction%20chain | An addition-subtraction chain, a generalization of addition chains to include subtraction, is a sequence a0, a1, a2, a3, ... that satisfies
An addition-subtraction chain for n, of length L, is an addition-subtraction chain such that . That is, one can thereby compute n by L additions and/or subtractions. (Note that n need not be positive. In this case, one may also include a−1 = 0 in the sequence, so that n = −1 can be obtained by a chain of length 1.)
By definition, every addition chain is also an addition-subtraction chain, but not vice versa. Therefore, the length of the shortest addition-subtraction chain for n is bounded above by the length of the shortest addition chain for n. In general, however, the determination of a minimal addition-subtraction chain (like the problem of determining a minimum addition chain) is a difficult problem for which no efficient algorithms are currently known. The related problem of finding an optimal addition sequence is NP-complete (Downey et al., 1981), but it is not known for certain whether finding optimal addition or addition-subtraction chains is NP-hard.
For example, one addition-subtraction chain is: , , , . This is not a minimal addition-subtraction chain for n=3, however, because we could instead have chosen . The smallest n for which an addition-subtraction chain is shorter than the minimal addition chain is n=31, which can be computed in only 6 additions (rather than 7 for the minimal addition chain):
Like an addition chain, an addition-subtraction chain can be used for addition-chain exponentiation: given the addition-subtraction chain of length L for n, the power can be computed by multiplying or dividing by x L times, where the subtractions correspond to divisions. This is potentially efficient in problems where division is an inexpensive operation, most notably for exponentiation on elliptic curves where division corresponds to a mere sign change (as proposed by Morain and Olivos, 1990).
Some hardwar |
https://en.wikipedia.org/wiki/IBM%20airgap | Airgap is a technique invented by IBM for fabricating small pockets of vacuum in between copper interconnects. The technique belongs to a general class of similar techniques that replaces solid low-κ dielectrics with air-filled or vacuum pockets.
Description
By insulating copper interconnects (wires) on an integrated circuit (IC) with vacuum holes, capacitance can be minimized enabling ICs to work faster or draw less power. A vacuum is believed to be the ultimate insulator for wiring capacitance, which occurs when two adjacent wires on an IC draw electrical energy from one another, generating undesirable heat and slowing the speed at which data can move through an IC. IBM estimates that this technology alone can lead to 35% higher speeds in current flow or 15% lower power consumption.
Fabrication techniques
The technique fabricates air gaps on a large scale by exploiting the self-assembly properties of certain polymers. These polymers can be easily integrated into the process modules (a collection of related steps that fabricate a structure on an integrated circuit) used in conventional CMOS fabrication, avoiding the costs of heavily modifying the process technology (the collection of process modules that produces an integrated circuit).
The technique deposits a polymer material over the entire wafer, and removes it at a later stage. When the polymer is removed, it creates trillions of evenly spaced vacuum pockets that are 20 nanometers in diameter. IBM has demonstrated this technique in the laboratory, and has deployed it in its East Fishkill, New York fabrication plant, where prototype POWER6 processors using this technology have been fabricated. The technique was scheduled to be featured in production-ready process technology in 2009, as part of IBM's 45 nm node, after which it would also be available to IBM's clients.
History
Airgap was developed in a collaborative effort between IBM's Almaden Research Center and T.J. Watson Research Center, and the Unive |
https://en.wikipedia.org/wiki/XOT | XOT (X.25 Over TCP) is a protocol developed by Cisco Systems that enables X.25 packets to be encapsulated and routed through TCP/IP connections instead of LAPB links. In 2012, X.25 tunnelled over TCP/IP using XOT was noted as by then being likely more common in actual use than physical X.25 over LAPB. |
https://en.wikipedia.org/wiki/Searching%20the%20conformational%20space%20for%20docking | In molecular modelling, docking is a method which predicts the preferred orientation of one molecule to another when bound together in a stable complex. In the case of protein docking, the search space consists of all possible orientations of the protein with respect to the ligand. Flexible docking in addition considers all possible conformations of the protein paired with all possible conformations of the ligand.
With present computing resources, it is impossible to exhaustively explore these search spaces; instead, there are many strategies which attempt to sample the search space with optimal efficiency. Most docking programs in use account for a flexible ligand, and several attempt to model a flexible protein receptor. Each "snapshot" of the pair is referred to as a pose.
Molecular dynamics (MD) simulations
In this approach, proteins are typically held rigid, and the ligand is allowed to freely explore their conformational space. The generated conformations are then docked successively into the protein, and an MD simulation consisting of a simulated annealing protocol is performed. This is usually supplemented with short MD energy minimization steps, and the energies determined from the MD runs are used for ranking the overall scoring. Although this is a computer-expensive method (involving potentially hundreds of MD runs), it has some advantages: for example, no specialized energy/scoring functions are required. MD force-fields can typically be used to find poses that are reasonable and can be compared with experimental structures.
The Distance Constrained Essential Dynamics method (DCED) has been used to generate multiple structures for docking, called eigenstructures. This approach, although avoiding most of the costly MD calculations, can capture the essential motions involved in a flexible receptor, representing a form of coarse-grained dynamics.
Shape-complementarity methods
The most common technique used in many docking programs, shape-complemen |
https://en.wikipedia.org/wiki/Scoring%20functions%20for%20docking | In the fields of computational chemistry and molecular modelling, scoring functions are mathematical functions used to approximately predict the binding affinity between two molecules after they have been docked. Most commonly one of the molecules is a small organic compound such as a drug and the second is the drug's biological target such as a protein receptor. Scoring functions have also been developed to predict the strength of intermolecular interactions between two proteins or between protein and DNA.
Utility
Scoring functions are widely used in drug discovery and other molecular modelling applications. These include:
Virtual screening of small molecule databases of candidate ligands to identify novel small molecules that bind to a protein target of interest and therefore are useful starting points for drug discovery
De novo design (design "from scratch") of novel small molecules that bind to a protein target
Lead optimization of screening hits to optimize their affinity and selectivity
A potentially more reliable but much more computationally demanding alternative to scoring functions are free energy perturbation calculations.
Prerequisites
Scoring functions are normally parameterized (or trained) against a data set consisting of experimentally determined binding affinities between molecular species similar to the species that one wishes to predict.
For currently used methods aiming to predict affinities of ligands for proteins the following must first be known or predicted:
Protein tertiary structure – arrangement of the protein atoms in three-dimensional space. Protein structures may be determined by experimental techniques such as X-ray crystallography or solution phase NMR methods or predicted by homology modelling.
Ligand active conformation – three-dimensional shape of the ligand when bound to the protein
Binding-mode – orientation of the two binding partners relative to each other in the complex
The above information yields the three-di |
https://en.wikipedia.org/wiki/Hayashi%20limit | The Hayashi limit is a theoretical constraint upon the maximum radius of a star for a given mass. When a star is fully within hydrostatic equilibrium—a condition where the inward force of gravity is matched by the outward pressure of the gas—the star can not exceed the radius defined by the Hayashi limit. This has important implications for the evolution of a star, both during the formulative contraction period and later when the star has consumed most of its hydrogen supply through nuclear fusion.
A Hertzsprung-Russell diagram displays a plot of a star's surface temperature against the luminosity. On this diagram, the Hayashi limit forms a nearly vertical line at about 3,500 K. The outer layers of low temperature stars are always convective, and models of stellar structure for fully convective stars do not provide a solution to the right of this line. Thus in theory, stars are constrained to remain to the left of this limit during all periods when they are in hydrostatic equilibrium, and the region to the right of the line forms a type of "forbidden zone". Note, however, that there are exceptions to the Hayashi limit. These include collapsing protostars, as well as stars with magnetic fields that interfere with the internal transport of energy through convection.
Red giants are stars that have expanded their outer envelope in order to support the nuclear fusion of helium. This moves them up and to the right on the H-R diagram. However, they are constrained by the Hayashi limit not to expand beyond a certain radius.
The Hayashi limit is named after Chūshirō Hayashi, a Japanese astrophysicist.
See also
Hayashi track
Eddington limit |
https://en.wikipedia.org/wiki/Shashlik%20%28physics%29 | In high energy physics detectors, shashlik is a layout for a sampling calorimeter. It refers to a stack of alternating slices of absorber (e.g. lead, brass) and scintillator materials (crystal or plastic), which is penetrated by a wavelength shifting fiber running perpendicular to the absorber and scintillator tiles.
The absorber has a small interaction length, so that a particle radiates energy in a short track. The scintillator material produces visible light when transversed by the particle's radiated energy. This occurs with an electromagnetic calorimeter, in the form of photons and/or electron+positron pairs. The energy of the particle may be then measured by the intensity of scintillation light produced by the various scintillator slices. An example detector that uses a shashlik electromagnetic calorimeter is the LHCb detector.
This type of calorimeter was likely named after the shashlik, a popular form of shish kebab sold by street vendors in the former Soviet Union, by the Russian and Ukrainian scientists who first proposed it. |
https://en.wikipedia.org/wiki/Trymedia | Trymedia Systems, Inc. is a division of RealNetworks that provides digital distribution services based on its proprietary ActiveMARK DRM and digital distribution technology. Trymedia is headquartered in San Francisco, with offices in Berkshire and Alicante.
Overview
Trymedia was founded in 1999 as Trymedia Systems, Inc. by cousins Alex Torrubia and Andres Torrubia. The company was launched in Spain, and after a round of fund-raising in New York, relocated to San Francisco. Macrovision acquired Trymedia for US$34 million on July 26, 2005. With the acquisition, Macrovision launched a new games division, Trymedia Games Division, based around Trymedia employees. Trymedia was not a profitable operation, losing $14.5 million on revenue of just over $9 million in 2007. On February 22, 2008, RealNetworks announced it had acquired Trymedia from Macrovision for an undisclosed sum, reported in a Macrovision conference call to be $4million.
Trymedia operates an online network of digitally distributed computer games. The network is integrated into Microsoft's digital locker service, and provides white label online retail services to affiliates such as Electronics Boutique and GameSpot.
ActiveMARK
ActiveMARK is a technology suite of Trymedia for secure digital distribution. It provides DRM protection for software distributed digitally or by CDs/DVD, along with commerce, distribution, administration and marketing services.
Trygames
Trygames, a division of Trymedia, was a retail website offering computer games from the Trymedia games network for download, trial and purchase. It was launched in 2001. The Trygames website was closed and redirected to the GameHouse website in 2014.
See also
TiVo Corporation |
https://en.wikipedia.org/wiki/SiReNT | The Singapore Satellite Positioning Reference Network (SiReNT), is an infrastructure network launched by the Survey Services section of the Singapore Land Authority in 2006. Its purpose is to define Singapore's official spatial reference framework and to support the cadastral system in SVY21. It is a multi-purpose high precision positioning infrastructure which provides both Post Process Differential Global Positioning System (DGPS) DGPS services and Real Time DGPS services. The system supports all types of GPS positioning modes and formats.
SiReNT comprises five GPS reference stations connected to a data control centre at government data centre. Four of the five reference stations are located at the extreme corners of the island of Singapore, with the fifth located in the centre of the island. The four external reference stations are located at Nanyang Technological University, Keppel Club, Loyang, and Senoko, with the designations SNTU, SKEP, SLOY, and SSEK, respectively. The central location is at Nanyang Polytechnic, designated by SNYP. The entire set-up is made up of advanced GPS equipment and sophisticated computer hardware, software, communications and network.
SiReNT supports a great variety of applications. It provides data reliability, efficiency and productivity of survey work for land surveyors with the aid of GPS technology. It also offers a wide range of GPS data services with various accuracy levels ranging from metres to centimetres to suit different applications from positioning to tracking and monitoring.
These GPS reference stations receive satellite signals 24 hours a day and transmit GPS data continuously to the data control centre for storage and processing. Corrections processed from the data are then streamed to subscribed users.
SiReNT offers 4 types of services, namely Post Processing (PP) On-Demand, Post Processing (PP) Archive, Real Time Kinematic (RTK) and low accuracy Differential Global Positioning System (DGPS) to suit different |
https://en.wikipedia.org/wiki/Strategic%20move | A strategic move in game theory is an action taken by a player outside the defined actions of the game in order to gain a strategic advantage and increase one's payoff. Strategic moves can either be unconditional moves or response rules. The key characteristics of a strategic move are that it involves a commitment from the player, meaning the player can only restrict her own choices and that the commitment has to be credible, meaning that once employed it must be in the interest of the player to follow through with the move. Credible moves should also be observable to the other players.
Strategic moves are not warnings or assurances. Warnings and assurances are merely statements of a player's interest, rather than an actual commitment from the player.
The term was coined by Thomas Schelling in his 1960 book, The Strategy of Conflict, and has gained wide currency in political science and industrial organization. |
https://en.wikipedia.org/wiki/Sensu | Sensu is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular concept, but it also appears in expressions that indicate the convention or context of the usage.
Common qualifiers
Sensu is the ablative case of the noun sensus, here meaning "sense". It is often accompanied by an adjective (in the same case). Three such phrases are:
sensu stricto – "in the strict sense", abbreviation s.s. or s.str.;
sensu lato – "in the broad sense", abbreviation s.l.;
sensu amplo – "in a relaxed, generous (or 'ample') sense", a similar meaning to sensu lato.
Søren Kierkegaard uses the phrase sensu eminenti to mean "in the pre-eminent [or most important or significant] sense".
When appropriate, comparative and superlative adjectives may also be used to convey the meaning of "more" or "most". Thus sensu stricto becomes sensu strictiore ("in the stricter sense" or "more strictly speaking") and sensu strictissimo ("in the strictest possible sense" or "most strictly speaking").
Current definitions of the plant kingdom (Plantae) offer a biological example of when such phrases might be used. One definition of Plantae is that it consists of all green plants (comprising green algae and land plants), all red algae and all glaucophyte algae. A stricter definition excludes the red and glaucophyte algae; the group defined in this way could be called Plantae in sensu stricto. An even stricter definition excludes green algae, leaving only land plants; the group defined in this way could be called Plantae in sensu strictiore.
Conversely, where convenient, some authors derive expressions such as "sensu non strictissimo", meaning "not in the narrowest possible sense".
A similar form is in use to indicate the sense of a particular context, such as "Nonmonophyletic groups are ... nonnatural (sensu cladistics) in that . |
https://en.wikipedia.org/wiki/Victor%20Kraft | Victor Kraft (4 July 1880 – 3 January 1975) was an Austrian philosopher. He is best known for being a member of the Vienna Circle.
Early life and education
Kraft studied philosophy, geography and history at the University of Vienna. He participated in the events of the university's Philosophical Society, as well as with private circles (especially Oskar Ewald, Otto Weininger and Othmar Spann). He received in 1903 his Ph.D. with a dissertation on "The Knowledge of the External World". Then he moved to Berlin to continue his studies under Georg Simmel, Wilhelm Dilthey and Carl Stumpf at the University of Berlin. Kraft started working in 1912 at the university's library, where he was a scientific civil servant ("Beamter") until 1939. In 1914 he completed his habilitation under Adolf Stöhr with his book "Weltbegriff und Erkenntnisbegriff" (The Concept of World and the Concept of Knowledge). Kraft attend regularly the Vienna Circle until its dissolution, and at the same time was also a member of the Gomperz Circle and had contacts to the so-called periphery of the Vienna Circle (e.g., Karl Popper). Victor Kraft received the title of associate professor for theoretical philosophy in 1924.
Academic career
After the Anschluss, Kraft was forced to leave his librarian position because of his wife's Jewish background. He lost his habilitation as university teacher as well. Kraft continued his philosophical research with great difficulties as "inner emigrant" during the Nazi regime.
He regained his post at the university library in 1945, and became Generalstaatsbibliothekar (national librarian) in 1947. In this year he was also appointed associate professor for philosophy. Three years later he became full professor and co-director of the school of philosophy. He retired from his post in 1952. Kraft kept his research and publishing until his death. The Kraft Circle, which he chaired between 1949 and 1952/3, was named after him, and it was during this period that he supervise |
https://en.wikipedia.org/wiki/National%20Biodiversity%20Network | The National Biodiversity Network (UK) (NBN) is a collaborative venture set up in 2000 in the United Kingdom committed to making biodiversity information available through various media, including on the internet via the NBN Atlas—the data search website of the NBN.
Description
It is estimated that up to 60,000 people routinely record biodiversity information in the UK and Ireland. Most of this effort is voluntary and is organised through about 2,000 national societies and recording schemes. The UK government through its agencies also collects biodiversity data and one of the principal elements for the collation and interpretation of this data is the network of Local Environmental Records Centres.
In 2012, it had been listed in the top 1,000 UK charities that raised most donations.
NBN Trust
The NBN Trust—the organisation facilitating the building of the Network—supports agreed standards for the collection, collation and exchange of biodiversity data and encourages improved access. The present partnership consists of over 200 public and voluntary organisations and individual members.
The NBN Atlas currently holds over 230 million species records from over 900 different datasets (September 2020). Data on the NBN Atlas can be accessed by anyone interested in UK, Northern Ireland and Isle of Man wildlife and can be searched at many different levels, as it allows the viewing of distribution maps and the downloading of data by using a variety of interactive tools. The maps can be customised by date range and can show changes in a species’ distribution.
The organisation believes that, by providing tools to make wildlife data accessible in a digitised and exchangeable form and by providing easy access to the information people need, wise and informed decisions can be made to ensure the natural environment is protected now and for future generations.
In April 2017 the NBN Atlas replaced the NBN Gateway.
Team
The National Biodiversity Network Trust employs a team to |
https://en.wikipedia.org/wiki/Archard%20equation | The Archard wear equation is a simple model used to describe sliding wear and is based on the theory of asperity contact. The Archard equation was developed much later than (sometimes also known as energy dissipative hypothesis), though both came to the same physical conclusions, that the volume of the removed debris due to wear is proportional to the work done by friction forces. Theodor Reye's model became popular in Europe and it is still taught in university courses of applied mechanics. Until recently, Reye's theory of 1860 has, however, been totally ignored in English and American literature where subsequent works by Ragnar Holm and John Frederick Archard are usually cited. In 1960, and Mikhail Alekseevich Babichev published a similar model as well. In modern literature, the relation is therefore also known as Reye–Archard–Khrushchov wear law. In 2022, the steady-state Archard wear equation was extended into the running-in regime using the bearing ratio curve representing the initial surface topography.
Equation
where:
Q is the total volume of wear debris produced
K is a dimensionless constant
W is the total normal load
L is the sliding distance
H is the hardness of the softest contacting surfaces
Note that is proportional to the work done by the friction forces as described by Reye's hypothesis.
Also, K is obtained from experimental results and depends on several parameters. Among them are surface quality, chemical affinity between the material of two surfaces, surface hardness process, heat transfer between two surfaces and others.
Derivation
The equation can be derived by first examining the behavior of a single asperity.
The local load , supported by an asperity, assumed to have a circular cross-section with a radius , is:
where P is the yield pressure for the asperity, assumed to be deforming plastically. P will be close to the indentation hardness, H, of the asperity.
If the volume of wear debris, , for a particular asperity is a hemis |
https://en.wikipedia.org/wiki/Sudanese%20goat%20marriage%20incident | In 2006, a South Sudanese man named Charles Tombe was forced to "marry" a goat with which he was caught engaging in sexual activity, in the Hai Malakal suburb of Juba, at the time part of Sudan. The owner of the goat subdued the perpetrator and asked village elders to consider the matter. One elder noted that he and the other elders found the perpetrator, tied up by the owner, at the door of the goat shed. The goat's owner reported that, "They said I should not take him to the police, but rather let him pay a dowry for my goat because he used it as his wife." The perpetrator was thus ordered to "marry" the goat, pay the cost of the goat and pay a dowry of SD 15,000 (equating to US$50 in 2006, the GDP per capita was US$1,522 for 2008), with half of the dowry up front. The goat apparently acquired the name "Rose" during the elders' deliberations as part of a joke.
On 3 May 2007, it was reported that the goat had died, having choked on a plastic bag. The goat was survived by a four-month-old male kid. In November 2013, the South Sudan Law Society called for a review of all South Sudan's laws to abolish bizarre or cruel practices under customary law, such as "a man being forced to marry a goat called "Rose" after deflowering her."
Press attention
The story, first published on 24 February 2006 on the BBC website, attracted massive attention and was republished on numerous newspapers, blogs and other websites. Even a year after publication, the story was consistently among the BBC's 10 most emailed articles, with many visitors to the BBC news site passing the tale on to friends. The story received over 100,000 hits on five successive days long after its original publication, and was read by millions of people. The BBC, astonished at this popularity, wondered if there was a campaign to keep the tale at the top of its rankings; however, an investigation by its senior software engineer, Gareth Owen, determined that the demand was genuine.
The BBC honoured the goat with |
https://en.wikipedia.org/wiki/Flyback%20diode | A flyback diode is any diode connected across an inductor used to eliminate flyback, which is the sudden voltage spike seen across an inductive load when its supply current is suddenly reduced or interrupted. It is used in circuits in which inductive loads are controlled by switches, and in switching power supplies and inverters.
Flyback circuits have been used since 1930 and were refined starting in 1950 for use in television receivers. The word flyback comes from the horizontal movement of the electron beam in a cathode ray tube, because the beam flew back to begin the next horizontal line.
This diode is known by many other names, such as snubber diode, commutating diode, freewheeling diode, suppressor diode, clamp diode, or catch diode.
Operation
Fig. 1 shows an inductor connected to a battery - a constant voltage source. The resistor represents the small residual resistance of the inductor's wire windings. When the switch is closed, the voltage from the battery is applied to the inductor, causing current from the battery's positive terminal to flow down through the inductor and resistor. The increase in current causes a back EMF (voltage) across the inductor due to Faraday's law of induction which opposes the change in current. Since the voltage across the inductor is limited to the battery's voltage of 24 volts, the rate of increase of the current is limited to an initial value of so the current through the inductor increases slowly as energy from the battery is stored in the inductor's magnetic field. As the current rises, more voltage is dropped across the resistor and less across the inductor, until the current reaches a steady value of with all the battery voltage across the resistance and none across the inductance.
However, the current drops rapidly when the switch is opened in Fig. 2. The inductor resists the drop in current by developing a very large induced voltage of polarity in the opposite direction of the battery, positive at the lower end |
https://en.wikipedia.org/wiki/Cystatin%20C | Cystatin C or cystatin 3 (formerly gamma trace, post-gamma-globulin, or neuroendocrine basic polypeptide), a protein encoded by the CST3 gene, is mainly used as a biomarker of kidney function. Recently, it has been studied for its role in predicting new-onset or deteriorating cardiovascular disease. It also seems to play a role in brain disorders involving amyloid (a specific type of protein deposition), such as Alzheimer's disease.
In humans, all cells with a nucleus (cell core containing the DNA) produce cystatin C as a chain of 120 amino acids. It is found in virtually all tissues and body fluids. It is a potent inhibitor of lysosomal proteinases (enzymes from a special subunit of the cell that break down proteins) and probably one of the most important extracellular inhibitors of cysteine proteases (it prevents the breakdown of proteins outside the cell by a specific type of protein degrading enzymes). Cystatin C belongs to the type 2 cystatin gene family.
Role in medicine
Kidney function
Glomerular filtration rate (GFR), a marker of kidney health, is most accurately measured by injecting compounds such as inulin, radioisotopes such as 51chromium-EDTA, 125I-iothalamate, 99mTc-DTPA or radiocontrast agents such as iohexol, but these techniques are complicated, costly, time-consuming and have potential side-effects.
Creatinine is the most widely used biomarker of kidney function. It is inaccurate at detecting mild renal impairment, and levels can vary with muscle mass but not with protein intake. Urea levels might change with protein intake.
Formulas such as the Cockcroft and Gault formula and the MDRD formula (see Renal function) try to adjust for these variables.
Cystatin C has a low molecular weight (approximately 13.3 kilodaltons), and it is removed from the bloodstream by glomerular filtration in the kidneys. If kidney function and glomerular filtration rate decline, the blood levels of cystatin C rise. Cross-sectional studies (based on a single point in t |
https://en.wikipedia.org/wiki/Tableau%20de%20Concordance | The Tableau de Concordance was the main French diplomatic code used during World War I; the term also refers to any message sent using the code. It was a superenciphered four-digit code that was changed three times between 1 August 1914 and 15 January 1915.
The Tableau de Concordance is considered superenciphered because there is more than one step required to use it. First, each word in a message is replaced by four digits via a codebook. These four digits are divided into three groups (one digit, two digits, one digit) so that when the whole message has been translated into code, the four-digit sets can be put together so it looks like the entire message is made up of two-digit pairs. This is called a "Straddle Gimmick." Then, in turn, each of these two digit pairs (and the single digits at the beginning and end) are replaced by two letters. The letters are then combined with no spaces for the final ciphertext.
The manual for the Tableau de Concordance included the instruction that if there was not adequate time for completely enciphering the message, it should simply be sent in clear, because a partially enciphered message would have provided insight into the inner workings of the code.
Sources
The Codebreakers, by David Kahn, copyright 1967, 1996
France in World War I
Cryptography |
https://en.wikipedia.org/wiki/Vern%20Poythress | Vern Sheridan Poythress (born 1946) is an American philosopher, theologian, New Testament scholar and mathematician, who is currently the New Testament chair of the ESV Oversight Committee. He is also the Distinguished Professor of New Testament, Biblical Interpretation, and Systematic Theology at Westminster Theological Seminary and editor of Westminster Theological Journal.
Biography
Poythress was born in Madera, California in 1946 to Ransom H. Poythress and Carola N. Poythress. He graduated from Bullard High School in Fresno, California.
At the age of 20, Poythress earned a B.S. in mathematics with honor (valedictorian) from California Institute of Technology, in the year 1966. While there, he became a Putnam Fellow in 1964. He received his Ph.D. in mathematics from Harvard University, finishing in 1970. Westminster Theological Seminary awarded him both an M.Div and a Th.M in apologetics for work done in the years 1971-74. He earned an M.Litt from the University of Cambridge in New Testament studies during 1974-76. He received a Th.D. in New Testament from the University of Stellenbosch.
In 1983, Poythress married Diane M. Poythress. They have two sons, Ransom Poythress and Justin Poythress.
As of 2016, he was teaching New Testament and occasional courses on the philosophies of science and language at Westminster Theological Seminary in Philadelphia, work he began in 1976. His blog with John M. Frame was listed in early 2018 as one of the top 50 Christian popular culture sites.
Thought
Poythress views scientific law as a form of the word of God. In 1976, Poythress wrote a chapter on "A Biblical View of Mathematics," in which he argued (among other things) that number is eternal because the Trinity is eternal. In a 1983 article, he suggested that mathematics is the rhyme of the universe. His philosophy of science draws on the work of Thomas Kuhn.
Publications
Poythress has published a number of books in different fields — Christian philosophy of science, |
https://en.wikipedia.org/wiki/Bicoid%203%E2%80%B2-UTR%20regulatory%20element | The bicoid 3′-UTR regulatory element is an mRNA regulatory element that controls the gene expression of the bicoid protein in fruitfly Drosophila melanogaster.
The structured RNA element consists of four domains (denoted as II, III, IV and V) in the 3′UTR of the mRNA. It is essential for the correct transport and localisation of bicoid mRNA during oocyte and embryo differentiation, which has been studied most thoroughly in the development of Drosophila melanogaster (fruitfly) larvae. |
https://en.wikipedia.org/wiki/Kelvin%20functions | In applied mathematics, the Kelvin functions berν(x) and beiν(x) are the real and imaginary parts, respectively, of
where x is real, and , is the νth order Bessel function of the first kind. Similarly, the functions kerν(x) and keiν(x) are the real and imaginary parts, respectively, of
where is the νth order modified Bessel function of the second kind.
These functions are named after William Thomson, 1st Baron Kelvin.
While the Kelvin functions are defined as the real and imaginary parts of Bessel functions with x taken to be real, the functions can be analytically continued for complex arguments With the exception of bern(x) and bein(x) for integral n, the Kelvin functions have a branch point at x = 0.
Below, is the gamma function and is the digamma function.
ber(x)
For integers n, bern(x) has the series expansion
where is the gamma function. The special case ber0(x), commonly denoted as just ber(x), has the series expansion
and asymptotic series
,
where
bei(x)
For integers n, bein(x) has the series expansion
The special case bei0(x), commonly denoted as just bei(x), has the series expansion
and asymptotic series
where α, , and are defined as for ber(x).
ker(x)
For integers n, kern(x) has the (complicated) series expansion
The special case ker0(x), commonly denoted as just ker(x), has the series expansion
and the asymptotic series
where
kei(x)
For integer n, kein(x) has the series expansion
The special case kei0(x), commonly denoted as just kei(x), has the series expansion
and the asymptotic series
where β, f2(x), and g2(x) are defined as for ker(x).
See also
Bessel function |
https://en.wikipedia.org/wiki/FLAIM | FLAIM (Framework for Log Anonymization and Information Management) is a modular tool designed to allow computer and network log sharing through application of complex data sanitization policies.
FLAIM is aimed at 3 different user communities. First, FLAIM can be used by the security engineer who is investigating a broad incident spanning multiple organizations. Because of the sensitivity inherent in security relevant logs, many organizations are reluctant to share them. However, this reluctance inhibits the sharing necessary to investigate intrusions that commonly span organizational boundaries. Second, anyone designing log analysis or computer forensics tools needs data with which they can test their tools. The larger and more diverse the data set, the more robust they can make their tools. For many, this means they must gather many logs from outside sources, not just what they can generate in-house. Again, this requires log sharing. Third, researchers in many computer science disciplines (e.g., network measurements, computer security, etc.) need large and diverse data sets to study. Having data sanitization tools available makes organizations more willing to share with these researchers their own logs.
FLAIM is available under the Open Source Initiative approved University of Illinois/NCSA Open Source License. This is BSD-style license. It runs on Unix and Unix-like systems, including Linux, FreeBSD, NetBSD, OpenBSD and Mac OS X.
While FLAIM is not the only log anonymizer, it is unique in its flexibility to create complex XML policies and its support for multiple log types. More specifically, it is the only such tool to meet the following 4 goals. (1) FLAIM provides a diverse set of anonymization primitives. (2) FLAIM supports multiple log type, including linux process accounting logs, netfilter alerts, tcpdump traces and NFDUMP NetFlows. (3) With a flexible anonymization policy language, complex policies that make trade-offs between information loss and secur |
https://en.wikipedia.org/wiki/Trizol | TRIzol is a widely used chemical solution used in the extraction of DNA, RNA, and proteins from cells. The solution was initially used and published by Piotr Chomczyński and Nicoletta Sacchi in 1987.
TRIzol is the brand name of guanidinium thiocyanate from the Ambion part of Life Technologies, and Tri-Reagent is the brand name from MRC, which was founded by Chomczynski.
Uses in extraction
The correct name of the method is guanidinium thiocyanate-phenol-chloroform extraction. The use of TRIzol can result in DNA yields comparable to other extraction methods, and it leads to >50% bigger RNA yield. An alternative method for RNA extraction is phenol extraction and TCA/acetone precipitation. Chloroform should be exchanged with 1-bromo-3-chloropropane when using the new generation TRI Reagent.
DNA and RNA from TRIzol and TRI reagent can also be extracted using the Direct-zol Miniprep kit by Zymo Research. This method eliminates the use of Chloroform and 1-bromo-3-chloropropane completely, bypassing phase-separation and precipitation steps.
TRIzol is light-sensitive and is often stored in a dark-colored, glass container covered in foil. It is stored at room temperature.
When used, it resembles cough syrup, bright pink. The smell of the phenol is extremely strong. TRIzol works by maintaining RNA integrity during tissue homogenization, while at the same time disrupting and breaking down cells and cell components.
Hazards
Vigilant caution should be taken while using TRIzol (due to the phenol and chloroform).
TRIzol is labeled as acute oral, dermal, and inhalation toxicity besides skin corrosion/irritation in the manufacturer MDS.
Exposure to TRIzol can be a serious health hazard. Exposure can lead to serious chemical burns, permanent scarring and kidney failure.
Experiments should be performed under a chemical hood, with lab coat, nitrile gloves and a plastic apron.
TRIzol waste should never be mixed with bleach or acids: the guanidinium thiocyanate in TRIzol rea |
https://en.wikipedia.org/wiki/Bi-wiring | Bi-wiring is a means of connecting a :loudspeaker to an audio :amplifier, primarily used in hi-fi systems. Normally, there is one pair of connectors on a loudspeaker and a single cable (two conductors) runs from the amplifier output to the terminals at the loudspeaker housing. From this point, connections are made to the loudspeaker drivers – usually through audio crossover networks.
In bi-wiring, each loudspeaker has two pairs of connectors and two cables are run from the same amplifier output to the speaker cabinet: one for the high frequency or tweeter driver and one for the low-frequency driver (through two separated crossover filters). The purported advantage of this split is that it "reduces magnetic interaction in the cable, resulting in better sound". However, technical analysis suggests that while bi-wired arrangements may be expected to have differences from single wired ones, these differences would normally be so small as to have little significance.
Some audiophiles feel that bi-wiring produces an audible improvement over standard single cabling. For example, John Atkinson, writing in Stereophile, states that he observes "subtle but important" differences, particularly in reduction of treble hardness and improvement in bass control in one review.
Critics of bi-wiring believe that both ways of making speaker connections are electrically equivalent (assuming no difference in speaker cable resistance), and thus cynically refer to the practice as "buy-wiring", implying it is nothing more than a marketing gimmick for buying more pairs of speaker wires.
Bi-wiring should not be confused with the hi-fi practice of bi-amping: the use of a separate amplifier for each driver, which brings improved separation of signal frequencies and removes the need for passive crossovers and the degraded efficiency, linearity, and cost that comes with them. |
https://en.wikipedia.org/wiki/Light-weight%20Identity | Light-weight Identity (LID), or Light Identity Management (LIdM), is an identity management system for online digital identities developed in part by NetMesh. It was first published in early 2005, and is the original URL-based identity system, later followed by OpenID. LID uses URLs as a verification of the user's identity, and makes use of several open-source protocols such as OpenID, Yadis, and PGP/GPG. |
https://en.wikipedia.org/wiki/Adult%20diaper | An adult diaper (or adult nappy in Australian English, British English, and Hiberno-English) is a diaper made to be worn by a person with a body larger than that of an infant or toddler. Diapers can be necessary for adults with various conditions, such as incontinence, mobility impairment, severe diarrhea or dementia. Adult diapers are made in various forms, including those resembling traditional child diapers, underpants, and pads resembling sanitary napkins (known as incontinence pads). Superabsorbent polymer is primarily used to absorb bodily wastes and liquids.
Alternative terms such as "briefs", "incontinence briefs", or "incontinence products" are also used.
Global market
The size of the adult diaper market in 2016 was $9.8 billion, an increase from $9.2 billion in 2015. Adult diaper sales in the United States were projected to rise 48 percent from 2015 to 2020, compared to 2.6 percent for baby diapers. The adult incontinence market in Japan was $1.8 billion in 2016, about 20 percent of the world market.
Uses
Health care
People with medical conditions which cause them to experience urinary or fecal incontinence often require diapers or similar products because they are unable to control their bladders or bowels. People who are bedridden or in wheelchairs, including those with good bowel and bladder control, may also wear diapers because they are unable to access the toilet independently. Those with cognitive impairment, such as dementia, may require diapers because they may not recognize their need to reach a toilet.
Absorbent incontinence products come in a wide range of types (drip collectors, pads, underwear and adult diapers), each with varying capacities and sizes. The largest volume of products that is consumed falls into the lower absorbency range of products, and even when it comes to adult diapers, the cheapest and least absorbent brands are used the most. This is not because people choose to use the cheapest and least absorbent brands, but rath |
https://en.wikipedia.org/wiki/The%20Malay%20Archipelago | The Malay Archipelago is a book by the British naturalist Alfred Russel Wallace which chronicles his scientific exploration, during the eight-year period 1854 to 1862, of the southern portion of the Malay Archipelago including Malaysia, Singapore, the islands of Indonesia, then known as the Dutch East Indies, and the island of New Guinea. It was published in two volumes in 1869, delayed by Wallace's ill health and the work needed to describe the many specimens he brought home. The book went through ten editions in the nineteenth century; it has been reprinted many times since, and has been translated into at least twelve languages.
The book describes each island that he visited in turn, giving a detailed account of its physical and human geography, its volcanoes, and the variety of animals and plants that he found and collected. At the same time, he describes his experiences, the difficulties of travel, and the help he received from the different peoples that he met. The preface notes that he travelled over 14,000 miles and collected 125,660 natural history specimens, mostly of insects though also thousands of molluscs, birds, mammals and reptiles.
The work was illustrated with engravings, based on Wallace's observations and collection, by the leading illustrators Thomas Baines, Walter Hood Fitch, John Gerrard Keulemans, E. W. Robinson, Joseph Wolf and T. W. Wood.
The Malay Archipelago attracted many reviews, with interest from scientific, geographic, church and general periodicals. Reviewers noted and sometimes disagreed with various aspects of his theories, especially the division of fauna and flora along what soon became known as the Wallace line, natural selection and uniformitarianism. Nearly all agreed that he had provided an interesting and comprehensive account of the geography, natural history, and peoples of the archipelago, which little was known about to readers at the time, in addition to the extensive breadth of specimens collected. The book is much |
https://en.wikipedia.org/wiki/Sprite%20%28lightning%29 | Sprites or red sprites are large-scale electric discharges that occur in the mesosphere, high above thunderstorm clouds, or cumulonimbus, giving rise to a varied range of visual shapes flickering in the night sky. They are usually triggered by the discharges of positive lightning between an underlying thundercloud and the ground.
Sprites appear as luminous red-orange flashes. They often occur in clusters above the troposphere at an altitude range of . Sporadic visual reports of sprites go back at least to 1886. They were first photographed on July 4, 1989, by scientists from the University of Minnesota and have subsequently been captured in video recordings thousands of times.
Sprites are sometimes inaccurately called upper-atmospheric lightning. However, they are cold plasma phenomena that lack the hot channel temperatures of tropospheric lightning, so they are more akin to fluorescent tube discharges than to lightning discharges. Sprites are associated with various other upper-atmospheric optical phenomena including blue jets and ELVES.
History
The earliest known report is by Toynbee and Mackenzie in 1886. Nobel laureate C. T. R. Wilson had suggested in 1925, on theoretical grounds, that electrical breakdown could occur in the upper atmosphere, and in 1956 he witnessed what possibly could have been a sprite. They were first documented photographically on July 6, 1989, when scientists from the University of Minnesota, using a low-light video camera, accidentally captured the first image of what would subsequently become known as a sprite.
Several years after their discovery they were named sprites (air spirits) after their elusive nature. Since the 1989 video capture, sprites have been imaged from the ground, from aircraft and from space, and have become the subject of intensive investigations. A featured high speed video that was captured by Thomas Ashcraft, Jacob L Harley, Matthew G McHarg, and Hans Nielsen in 2019 at about 100,000 frames per second is fast e |
https://en.wikipedia.org/wiki/CAVE-based%20authentication | CAVE-based Authentication (a.k.a. HLR Authentication, 2G Authentication, Access Authentication) is an access authentication protocol used in CDMA/1xRTT computer network systems.
CAVE (Cellular Authentication and Voice Encryption)
There are two network entities involved in CAVE-based authentication when roaming:
Authentication Center (AC) a.k.a. HLR/AC, AuC – Located in a roamer’s home network, the AC controls the authentication process and either authenticates the Mobile Station (Mobile Phone, MS) or shares SSD with the serving VLR to allow this authentication to occur locally. The AC must be provisioned with an A-key value for each MS. Authentication is predicated on the assumption that A-key value provisioned in an MS is the same as the A-key value provisioned in the AC. The AC is often co-located with the HLR and referred to as the HLR/AC. However, the AC could be a standalone network entity that serves one or more HLRs. Though the CDMA abbreviation is AC, the GSM abbreviation of AuC is sometimes used (albeit incorrectly in CDMA networks).
Visitor Location Register (VLR) – If SSD is shared with the visited network, the VLR locally authenticates the roamer. Otherwise, the VLR proxies authentication responses from roamers to their home HLR/AC for authentication.
The authentication controller is the entity that determines whether the response from the MS is correct. Depending upon whether SSD is shared, the authentication controller may be either the AC or VLR. In either case, CAVE-based authentication is based on the CAVE algorithm and the following two shared keys:
Authentication key (A-key) – A 64-bit primary secret key known only to the MS and AC. In the case of RUIM equipped mobiles, the A-key is stored on the RUIM; otherwise, it is stored in semi-permanent memory on the MS. The A-key is never shared with roaming partners. However, it is used to generate a secondary key known as SSD that may be shared with a roaming partner to enable local authentication in |
https://en.wikipedia.org/wiki/Electron%20beam%20ion%20trap | Electron beam ion trap (EBIT) is an electromagnetic bottle that produces and confines highly charged ions. An EBIT uses an electron beam focused with a powerful magnetic field to ionize atoms to high charge states by successive electron impact.
It was invented by M. Levine and R. Marrs at LLNL and LBNL.
Operation
The positive ions produced in the region where the atoms intercept the electron beam are tightly confined in their motion by the strong attraction exerted by the negative charge of the electron beam. Therefore, they orbit around the electron beam, crossing it frequently and giving rise to further collisions and ionization. To restrict the ion motion along the direction of the electron beam axis, trapping electrodes carrying positive voltages with respect to a central electrode are used.
The resulting ion trap can hold ions for many seconds and minutes, and conditions for reaching the highest charge states, up to bare uranium (U92+) can be achieved in this way.
The strong charge needed for radial confinement of the ions requires large electron beam currents of tens up to hundreds of milliampere. At the same time, high voltages (up to 200 kilovolts) are used for accelerating the electrons in order to achieve high charge states of the ions.
To avoid charge reduction of ions by collisions with neutral atoms from which they can capture electrons, the vacuum in the apparatus is usually maintained at UHV levels, with typical pressure values of only 10−12 torr, (~10−10 pascal).
Applications
EBITs are used to investigate the fundamental properties of highly charged ions e. g. by photon spectroscopy in particular in the context of relativistic atomic structure theory and quantum electrodynamics (QED). Their suitability to prepare and reproduce in a microscopic volume the conditions of high temperature astrophysical plasmas and magnetic confinement fusion plasmas make them very appropriate research tools. Other fields include the study of their interactions with |
https://en.wikipedia.org/wiki/Porphyromonas%20gingivalis | Porphyromonas gingivalis belongs to the phylum Bacteroidota and is a nonmotile, Gram-negative, rod-shaped, anaerobic, pathogenic bacterium. It forms black colonies on blood agar.
It is found in the oral cavity, where it is implicated in periodontal disease, as well as in the upper gastrointestinal tract, the respiratory tract and the colon. It has been isolated from women with bacterial vaginosis.
Collagen degradation observed in chronic periodontal disease results in part from the collagenase enzymes of this species. It has been shown in an in vitro study that P. gingivalis can invade human gingival fibroblasts and can survive in the presence of antibiotics. P. gingivalis invades gingival epithelial cells in high numbers, in which case both bacteria and epithelial cells survive for extended periods of time. High levels of specific antibodies can be detected in patients harboring P. gingivalis.
P. gingivalis infection has been linked to Alzheimer's disease and rheumatoid arthritis. It contains the enzyme peptidyl-arginine deiminase, which is involved in citrullination. Patients with rheumatoid arthritis have increased incidence of periodontal disease; antibodies against the bacterium are significantly more common in these patients.
P. gingivalis is divided into K-serotypes based upon capsular antigenicity of the various types. These serotypes have been the drivers of observations regarding bacterial cell to cell interactions to the associated serotype-dependent immune response and risk with pancreatic cancer.
Genome
The genome of P. gingivalis was described in 2003 revealing 1,990 open reading frames (i.e. protein-coding sequences), encoded by 2,343,479 bp, with an average G+C content of 48.3%. An estimated 463 genes are essential.
Virulence factors
Gingipain
Arg-gingipain (Rgp) and lys-gingipain (Kgp) are endopeptidase enzymes secreted by P. gingivalis. These gingipains serve many functions for the organism, contributing to its survival and virulence.
Arg |
https://en.wikipedia.org/wiki/Standard%20Carrier%20Alpha%20Code | The Standard Carrier Alpha Code (SCAC) is a privately controlled US code used to identify vessel operating common carriers (VOCC). It is typically two to four letters long. The National Motor Freight Traffic Association developed the SCAC code in the 1960s to help road transport companies computerize data and records.
Description
The Standard Carrier Alpha Code, a two-to-four letter identification, is used by the transportation industry to identify freight carriers in computer systems and shipping documents such as Bill of Lading, Freight Bill, Packing List, and Purchase Order. It is also used by the American National Standards Institute, Accredited Standards Committee X12, and United Nations EDIFACT for Electronic Data Interchange computer systems.
SCACs are commonly used by the automobile, petroleum, forest products, and chemical industries; as well as suppliers to retail businesses, carriers engaged in railroad piggyback trailers, and ocean container drayage. SCACs can be obtained online at http://www.nmfta.org.
Freight Carriers who participate in the Uniform Intermodal Interchange Agreement (UIIA) are required to maintain a SCAC.
Certain groups of SCACs are reserved for specific purposes. Codes ending with the letter "U" are reserved for the identification of freight containers. Codes ending with the letter "X" are reserved for the identification of privately owned railroad cars. Codes ending with the letter "Z" are reserved for the identification of truck chassis and trailers used in intermodal service.
SCAC is also used to identify an ocean carrier or self-filing party, such as a freight forwarder, for the Automated Manifest System used by US Customs and Border Protection for electronic import customs clearance and for manifest transmission as per the USA's "24 Hours Rule" which requires the carrier to transmit a cargo manifest to US Customs at least 24 hours prior to a vessel's departure at port of loading.
Widely used SCACs
The following is a list |
https://en.wikipedia.org/wiki/Introselect | In computer science, introselect (short for "introspective selection") is a selection algorithm that is a hybrid of quickselect and median of medians which has fast average performance and optimal worst-case performance. Introselect is related to the introsort sorting algorithm: these are analogous refinements of the basic quickselect and quicksort algorithms, in that they both start with the quick algorithm, which has good average performance and low overhead, but fall back to an optimal worst-case algorithm (with higher overhead) if the quick algorithm does not progress rapidly enough. Both algorithms were introduced by David Musser in , with the purpose of providing generic algorithms for the C++ Standard Library that have both fast average performance and optimal worst-case performance, thus allowing the performance requirements to be tightened.
However, in most C++ Standard Library implementations, a different "introselect" algorithm is used, which combines quickselect and heapselect, and has a worst-case running time of O(n log n). The C++ draft standard, as of 2022, does not have requirements on the worst-case performance, therefore allowing such choice.
Algorithms
Introsort achieves practical performance comparable to quicksort while preserving O(n log n) worst-case behavior by creating a hybrid of quicksort and heapsort. Introsort starts with quicksort, so it achieves performance similar to quicksort if quicksort works, and falls back to heapsort (which has optimal worst-case performance) if quicksort does not progress quickly enough. Similarly, introselect combines quickselect with median of medians to achieve worst-case linear selection with performance similar to quickselect.
Introselect works by optimistically starting out with quickselect and only switching to a worst-case linear-time selection algorithm (the Blum-Floyd-Pratt-Rivest-Tarjan median of medians algorithm) if it recurses too many times without making sufficient progress. The switching s |
https://en.wikipedia.org/wiki/Linear%20relation | In linear algebra, a linear relation, or simply relation, between elements of a vector space or a module is a linear equation that has these elements as a solution.
More precisely, if are elements of a (left) module over a ring (the case of a vector space over a field is a special case), a relation between is a sequence of elements of such that
The relations between form a module. One is generally interested in the case where is a generating set of a finitely generated module , in which case the module of the relations is often called a syzygy module of . The syzygy module depends on the choice of a generating set, but it is unique up to the direct sum with a free module. That is, if and are syzygy modules corresponding to two generating sets of the same module, then they are stably isomorphic, which means that there exist two free modules and such that and are isomorphic.
Higher order syzygy modules are defined recursively: a first syzygy module of a module is simply its syzygy module. For , a th syzygy module of is a syzygy module of a -th syzygy module. Hilbert's syzygy theorem states that, if is a polynomial ring in indeterminates over a field, then every th syzygy module is free. The case is the fact that every finite dimensional vector space has a basis, and the case is the fact that is a principal ideal domain and that every submodule of a finitely generated free module is also free.
The construction of higher order syzygy modules is generalized as the definition of free resolutions, which allows restating Hilbert's syzygy theorem as a polynomial ring in indeterminates over a field has global homological dimension .
If and are two elements of the commutative ring , then is a relation that is said trivial. The module of trivial relations of an ideal is the submodule of the first syzygy module of the ideal that is generated by the trivial relations between the elements of a generating set of an ideal. The concept of trivial rel |
https://en.wikipedia.org/wiki/Rule%20184 | Rule 184 is a one-dimensional binary cellular automaton rule, notable for solving the majority problem as well as for its ability to simultaneously describe several, seemingly quite different, particle systems:
Rule 184 can be used as a simple model for traffic flow in a single lane of a highway, and forms the basis for many cellular automaton models of traffic flow with greater sophistication. In this model, particles (representing vehicles) move in a single direction, stopping and starting depending on the cars in front of them. The number of particles remains unchanged throughout the simulation. Because of this application, Rule 184 is sometimes called the "traffic rule".
Rule 184 also models a form of deposition of particles onto an irregular surface, in which each local minimum of the surface is filled with a particle in each step. At each step of the simulation, the number of particles increases. Once placed, a particle never moves.
Rule 184 can be understood in terms of ballistic annihilation, a system of particles moving both leftwards and rightwards through a one-dimensional medium. When two such particles collide, they annihilate each other, so that at each step the number of particles remains unchanged or decreases.
The apparent contradiction between these descriptions is resolved by different ways of associating features of the automaton's state with particles.
The name of Rule 184 is a Wolfram code that defines the evolution of its states. The earliest research on Rule 184 is by and . In particular, Krug and Spohn already describe all three types of particle system modeled by Rule 184.
Definition
A state of the Rule 184 automaton consists of a one-dimensional array of cells, each containing a binary value (0 or 1). In each step of its evolution, the Rule 184 automaton applies the following rule to each of the cells in the array, simultaneously for all cells, to determine the new state of the cell:
An entry in this table defines the new state of |
https://en.wikipedia.org/wiki/Feud%20%28video%20game%29 | Feud is an adventure game designed by John Pickford for Binary Design and published in 1987 as the first game under the Bulldog Software label of Mastertronic. Versions were released for the Amiga, Amstrad CPC, Atari 8-bit family, Atari ST, Commodore 64, MS-DOS, MSX, and ZX Spectrum. The player takes on the role of the sorcerer Learic, and must fight his evil twin Leanoric.
Gameplay
The only real enemy is Leanoric. To achieve your objective, the player must collect many herbs scattered across the map and mix them in a cauldron to make offensive and defensive spells. The spells vary from fireballs and lightning to invisibility and even turning peaceful villagers into zombies. A compass indicates Leanoric's location. Several of the herbs are found in a garden, tended by a gardener. The gardener, though slow-moving, is also able to inflict damage on Learic.
Leanoric, as a non-player character, has to do the same thing, collecting herbs to mix in his cauldron before hunting you down in order to attack.
Development
After developing Zub, John Pickford went on to design a game that he wasn't going to program. This required designing the game on paper before development started and overseeing the work of a different programming team.
Reception
Reviewer "Ben" for CRASH wrote, "What a way to kick off a new label! Feud is completely brilliant. I love original games, so it is a real pleasure to see a cheapie that’s as ‘new’ in concept as this — and as playable." Robert Swan, in his favorable review for Atari User magazine, stated that the game has "fantastic graphics, great sound, addictive gameplay and plenty of action-packed screens." He also praised the game's low price. |
https://en.wikipedia.org/wiki/Phage%20group | The phage group (sometimes called the American Phage Group) was an informal network of biologists centered on Max Delbrück that contributed heavily to bacterial genetics and the origins of molecular biology in the mid-20th century. The phage group takes its name from bacteriophages, the bacteria-infecting viruses that the group used as experimental model organisms. In addition to Delbrück, important scientists associated with the phage group include: Salvador Luria, Alfred Hershey, Seymour Benzer, Charles Steinberg, Gunther Stent, James D. Watson, Frank Stahl, and Renato Dulbecco.
Origins of the phage group: people, ideas, experiments and personal relationships
Bacteriophages had been a subject of experimental investigation since Félix d'Herelle had isolated and developed methods for detecting and culturing them, beginning in 1917. Delbrück, a physicist-turned biologist seeking the simplest possible experimental system to probe the fundamental laws of life, first encountered phage during a 1937 visit to T. H. Morgan's fly lab at Caltech. Delbrück was unimpressed with Morgan's experimentally complex model organism Drosophila, but another researcher, Emory Ellis, was working with the more elementary phage. During the next few years, Ellis and Delbrück collaborated on methods of counting phage and tracking growth curves; they established the basic step-wise pattern of virus growth (the most obvious features of the lytic cycle).
Emory Ellis (1906–2003) and Max Delbrück (1906–1981)
In a retrospective article, Emory Ellis stated "Soon after Max Delbruck arrived at the Caltech Biology Division, intent on discovering how his background in physical sciences could be productively applied to biological problems, I showed him some step-growth curves. His first comment was ‘I don't believe it.’" However, as Ellis describes, Delbruck soon dispelled this initial reaction of disbelief by his own analysis of the phenomenon, and promptly joined in the work with enthusiasm, br |
https://en.wikipedia.org/wiki/Ballistic%20limit | The ballistic limit or limit velocity is the velocity required for a particular projectile to reliably (at least 50% of the time) penetrate a particular piece of material. In other words, a given projectile will generally not pierce a given target when the projectile velocity is lower than the ballistic limit. The term ballistic limit is used specifically in the context of armor; limit velocity is used in other contexts.
The ballistic limit equation for laminates, as derived by Reid and Wen is as follows:
where
is the ballistic limit
is a projectile constant determined experimentally
is the density of the laminate
is the static linear elastic compression limit
is the diameter of the projectile
is the thickness of the laminate
is the mass of the projectile
Additionally, the ballistic limit for small-caliber into homogeneous armor by TM5-855-1 is:
where
is the ballistic limit velocity in fps
is the caliber of the projectile, in inches
is the thickness of the homogeneous armor (valid from BHN 360 - 440) in inches
is the angle of obliquity
is the weight of the projectile, in lbs |
https://en.wikipedia.org/wiki/Acronis%20Secure%20Zone | Acronis Secure Zone is a hard disk partition type created and used by Acronis True Image as a backup storage target.
Overview
Backup applications typically use network storage for storing backup archives, but this can be problematic when such resources are not available. Acronis designed a solution to this problem by carving off part of the local disk as a proprietary partition, which they refer to as Acronis Secure Zone. Since this partition is accessibly only by True Image and Backup & Recovery, it functions as a backup target safe from malware, user files, or other uses or corruption. Acronis True Image can manage only one Acronis Secure Zone per computer but can restore data off others (e.g., when a portable hard drive is connected).
Technical Details
Although the Acronis Secure Zone has its own partition type, it is actually just a rebadged FAT32 partition labeled ACRONIS SZ, with "partition type" code set to . Knowing these requirements, one can manually create and/or manage existing Acronis Secure Zone using any partition manager. Since the Acronis Secure Zone is just a modified FAT32 partition type, it is possible to gain direct access to this partition by changing its partition type code to (FAT32 LBA).
Acronis True Image is designed to self-manage the backup archives stored to the Acronis Secure Zone. As such, all backup files are stored with autogenerated names in the root folder. If there is not enough free space for the next backup file, Acronis True Image will delete the oldest image set (base+incremental/differential files) in order to create space for the new files.
Original Equipment Manufacturer Secure Zone
OEM versions of True Image are designed to use a special "Original Equipment Manufacturer secure zone", which is technically the same as a regular Acronis Secure Zone, but uses a partition type of 0xBB, and typically contains only a single image file with the "factory default" operating system and application configuration set forth by |
https://en.wikipedia.org/wiki/Aegirosaurus | Aegirosaurus is an extinct genus of platypterygiine ophthalmosaurid ichthyosaurs known from the late Jurassic and early Cretaceous of Europe. It was originally named as a species of Ichthyosaurus.
Discovery and species
Originally described by Wagner (1853) as a species of the genus Ichthyosaurus (I. leptospondylus), the species Aegirosaurus leptospondylus has had an unstable taxonomic history. It has been referred to the species Ichthyosaurus trigonus posthumus (later reclassified in the dubious genus Macropterygius) in the past, and sometimes identified with Brachypterygius extremus. In 2000, Bardet and Fernández selected a complete skeleton in a private collection as the neotype for the species I. leptospondylus, as the only other described specimen was destroyed in World War II. A second specimen from the Munich collection was referred to the same taxon. Bardet and Fernández concluded that the neotype should be assigned to a new genus, Aegirosaurus. The name means 'Aegir (teutonic god of the ocean) lizard with slender vertebrae'.
Within the Ophthalmosauridae, scientists once believed Aegirosaurus was most closely related to Ophthalmosaurus. However, many subsequent cladistic analyses found it is more closely related to Sveltonectes (and probably to Undorosaurus). Aegirosaurus lineage was found to include Brachypterygius and Maiaspondylus, too, and to nest within the Platypterygiinae, which is the sister taxon of Ophthalmosaurinae.
Stratigraphic range
Aegirosaurus is known from the lower Tithonian (Upper Jurassic) of Bavaria, Germany. Its remains were discovered in the Solnhofen limestone formations, which have yielded numerous well-known fossils, such as Archaeopteryx, Compsognathus, and Pterodactylus.
In addition to its late Jurassic occurrence, Aegirosaurus has been discovered from the late Valanginian (early Cretaceous) of southeastern France (Laux-Montaux, department of Drôme; Vocontian Basin), the first diagnostic ichthyosaur recorded from the Valanginia |
https://en.wikipedia.org/wiki/Xilleon | Xilleon is a brand for a family of SoCs combining a low-power CPU with ASICs for accelerated video decompression and further functions for major worldwide broadcast networks (including PAL, NTSC, SECAM and ATSC) targeting digital television (i.e. products like set-top boxes, Integrated digital television, digital television adapters, smart TVs, etc.).
Technical features
Most Xilleon-branded SoCs have a
300 MHz MIPS 4Kc (MMU, no FPU)
ASIC simultaneously decompressing two standard-definition television and two high-definition television MPEG-2-compressed streams
two display controller
2D and 3D graphics engine
conditional access
transport demultiplexers
32/64 bit DDR/SDR interface
, PCI, USB, IR, I2C, I2S, Flash and PATA interfaces
It was revealed that the next generation of AVIVO, named as Unified Video Decoder (UVD) was based on Xilleon video processor to provide hardware decoding of H.264, and VC-1 video codec standards.
Both AMD TrueAudio and AMD's Unified Video Decoder (UVD) are based on the Cadence Tensilica Xtensa processor, which was originally licensed by ATI Technologies Inc. in 2004.
List of Xilleon-branded SoCs
History
Owner's of the brand Xilleon were ATI Technologies, later Advanced Micro Devices, now Broadcom.
While AMD announced the completion of acquisition of ATI Technologies on the third quarter of 2006, the Xilleon products would be sold under the AMD brand as AMD Xilleon.
On August 25, 2008, the Xilleon line was sold to the semiconductor company Broadcom.
A new line of Xilleon video processors for flat panel LCD TVs, named as Xilleon panel processors with four models 410, 411, 420 and 421, were announced on CES 2008. Supporting 1080p video resolution and featuring Technology advanced motion estimation, motion compensation and frame rate conversion technology based on enhanced phase-plane correlation technology, which converts 24 or 60 Hz input video signals to 100 or 120 Hz refresh rates used in most of the LCD TVs by creating ad |
https://en.wikipedia.org/wiki/Darboux%20frame | In the differential geometry of surfaces, a Darboux frame is a natural moving frame constructed on a surface. It is the analog of the Frenet–Serret frame as applied to surface geometry. A Darboux frame exists at any non-umbilic point of a surface embedded in Euclidean space. It is named after French mathematician Jean Gaston Darboux.
Darboux frame of an embedded curve
Let S be an oriented surface in three-dimensional Euclidean space E3. The construction of Darboux frames on S first considers frames moving along a curve in S, and then specializes when the curves move in the direction of the principal curvatures.
Definition
At each point of an oriented surface, one may attach a unit normal vector in a unique way, as soon as an orientation has been chosen for the normal at any particular fixed point. If is a curve in , parametrized by arc length, then the Darboux frame of is defined by
(the unit tangent)
(the unit normal)
(the tangent normal)
The triple defines a positively oriented orthonormal basis attached to each point of the curve: a natural moving frame along the embedded curve.
Geodesic curvature, normal curvature, and relative torsion
Note that a Darboux frame for a curve does not yield a natural moving frame on the surface, since it still depends on an initial choice of tangent vector. To obtain a moving frame on the surface, we first compare the Darboux frame of γ with its Frenet–Serret frame. Let
(the unit tangent, as above)
(the Frenet normal vector)
(the Frenet binormal vector).
Since the tangent vectors are the same in both cases, there is a unique angle α such that a rotation in the plane of N and B produces the pair t and u:
Taking a differential, and applying the Frenet–Serret formulas yields
where:
κg is the geodesic curvature of the curve,
κn is the normal curvature of the curve, and
τr is the relative torsion (also called geodesic torsion) of the curve.
Darboux frame on a surface
This section spec |
https://en.wikipedia.org/wiki/Vividness%20of%20Visual%20Imagery%20Questionnaire | The Vividness of Visual Imagery Questionnaire (VVIQ) was developed in 1973 by the British psychologist David Marks. The VVIQ consists of 16 items in four groups of 4 items in which the participant is invited to consider the mental image formed in thinking about specific scenes and situations. The vividness of the image is rated along a 5-point scale. The questionnaire has been widely used as a measure of individual differences in vividness of visual imagery. The large body of evidence confirms that the VVIQ is a valid and reliable psychometric measure of visual image vividness.
In 1995 Marks published a new version of the VVIQ, the VVIQ2. This questionnaire consists of twice the number of items and reverses the rating scale so that higher scores reflect higher vividness. More recently, Campos and Pérez-Fabello evaluated the reliability and construct validity of the VVIQ and the VVIQ2. Cronbach's reliabilities for both the VVIQ and the VVIQ-2 were found to be high. Estimates of internal consistency reliability and construct validity were found to be similar for the two versions.
Validation
The VVIQ has proved an essential tool in the scientific investigation of mental imagery as a phenomenological, behavioral and neurological construct. Marks' 1973 paper has been cited in close to 2000 studies of mental imagery in a variety of fields including cognitive psychology, clinical psychology and neuropsychology.
The procedure can be carried out with eyes closed and/or with eyes open. Total score on the VVIQ is a predictor of the person's performance in a variety of cognitive, motor, and creative tasks. For example, Marks (1973) reported that high vividness scores correlate with the accuracy of recall of coloured photographs.
The VVIQ is in several languages apart from English including Spanish, Japanese, French (Denis, 1982), and Polish (Jankowska and Karwowski, 2020). Factor analysis of the Spanish VVIQ by Campos, González, and Amor (2002) indicated a single factor t |
https://en.wikipedia.org/wiki/Focus%20stacking | Focus stacking (also known as focal plane merging and z-stacking or focus blending) is a digital image processing technique which combines multiple images taken at different focus distances to give a resulting image with a greater depth of field (DOF) than any of the individual source images. Focus stacking can be used in any situation where individual images have a very shallow depth of field; macro photography and optical microscopy are two typical examples. Focus stacking can also be useful in landscape photography.
Focus stacking offers flexibility: since it is a computational technique, images with several different depths of field can be generated in post-processing and compared for best artistic merit or scientific clarity. Focus stacking also allows generation of images physically impossible with normal imaging equipment; images with nonplanar focus regions can be generated. Alternative techniques for generating images with increased or flexible depth of field include wavefront coding, light-field cameras and tilt.
Technique
The starting point for focus stacking is a series of images captured at different focus distances; in each image different areas of the sample will be in focus. While none of these images has the sample entirely in focus they collectively contain all the data required to generate an image which has all parts of the sample in focus. In-focus regions of each image may be detected automatically, for example via edge detection or Fourier analysis, or selected manually. The in-focus patches are then blended together to generate the final image.
This processing is also called z-stacking, focal plane merging (or in French).
In photography
Getting sufficient depth of field can be particularly challenging in macro photography, because depth of field is smaller (shallower) for objects nearer the camera, so if a small object fills the frame, it is often so close that its entire depth cannot be in focus at once. Depth of field is normally incre |
https://en.wikipedia.org/wiki/MStar | MStar Semiconductor, Inc. () was a Taiwanese fabless semiconductor company specializing in mixed-mode integrated circuit technologies, based in Hsinchu Hsien. MStar made hardware for multimedia and wireless communications, in the form of display ICs and mixed-mode (i.e. combining analog and digital functions) ASIC/IPs, in addition to chip sets for GSM mobile handsets. MStar employed approx. 1300 in more than 10 branches worldwide. The company's revenue was around US$1067 million in 2010. The growth has been substantial, their revenue in 2005 was US$175 million. MStar is listed on the Taiwan Stock Exchange under the code 3697.
MStar was often referred as "Little-M" or "Morning Star" in Chinese community, as a contrary part of the bigger semiconductor company "Big-M", a.k.a. MediaTek.
MStar was a spin-off (2-1 stock split) from System General Technology in May 2002, where the power IC product line stayed in System General Technology while the employees with the display and RFID product lines transferred to the new spin-off. After the spin-off, System General Technology regretted the decision, and a 1-2 stock swap was taken to exchange the two companies back to their corresponding shareholders. Chairman and CEO of MStar was Wayne Liang (梁公偉), while Dr. Steve Yang (楊偉毅) was the executive vice president and co-founder.
In 2004, after being involved in a court case where in a ruling by the International Trade Commission (ITC), MStar Semiconductor were found guilty over infringing on a patent held by Genesis Microchip for a method to improve images on liquid-crystal-display (LCD) monitors and flat screen TVs.
On October 14, 2020, MStar came under investigation by the US International Trade Commission for allegedly infringing patents held by DIVX LLC of San Diego, California, USA.
Merger with MediaTek
On 22 June 2012 MediaTek Inc. () announced it purchased 212 million to 254 million shares of MStar ( - 40% to 48% of its outstanding shares) for 0.794 MediaTek shares a |
https://en.wikipedia.org/wiki/Maximum%20entropy%20spectral%20estimation | Maximum entropy spectral estimation is a method of spectral density estimation. The goal is to improve the spectral quality based on the principle of maximum entropy. The method is based on choosing the spectrum which corresponds to the most random or the most unpredictable time series whose autocorrelation function agrees with the known values. This assumption, which corresponds to the concept of maximum entropy as used in both statistical mechanics and information theory, is maximally non-committal with regard to the unknown values of the autocorrelation function of the time series. It is simply the application of maximum entropy modeling to any type of spectrum and is used in all fields where data is presented in spectral form. The usefulness of the technique varies based on the source of the spectral data since it is dependent on the amount of assumed knowledge about the spectrum that can be applied to the model.
In maximum entropy modeling, probability distributions are created on the basis of that which is known, leading to a type of statistical inference about the missing information which is called the maximum entropy estimate. For example, in spectral analysis the expected peak shape is often known, but in a noisy spectrum the center of the peak may not be clear. In such a case, inputting the known information allows the maximum entropy model to derive a better estimate of the center of the peak, thus improving spectral accuracy.
Method description
In the periodogram approach to calculating the power spectra, the sample autocorrelation function is multiplied by some window function and then Fourier transformed. The window is applied to provide statistical stability as well as to avoid leakage from other parts of the spectrum. However, the window limits the spectral resolution.
Maximum entropy method attempts to improve the spectral resolution by extrapolating the correlation function beyond the maximum lag in such a way that the entropy of the correspond |
https://en.wikipedia.org/wiki/Alternative%20oxidase | The alternative oxidase (AOX) is an enzyme that forms part of the electron transport chain in mitochondria of different organisms. Proteins homologous to the mitochondrial oxidase and the related plastid terminal oxidase have also been identified in bacterial genomes.
The oxidase provides an alternative route for electrons passing through the electron transport chain to reduce oxygen. However, as several proton-pumping steps are bypassed in this alternative pathway, activation of the oxidase reduces ATP generation. This enzyme was first identified as a distinct oxidase pathway from cytochrome c oxidase as the alternative oxidase is resistant to inhibition by the poison cyanide.
Function
This metabolic pathway leading to the alternative oxidase diverges from the cytochrome-linked electron transport chain at the ubiquinone pool. Alternative pathway respiration only produces proton translocation at Complex 1 (NADH dehydrogenase) and so has a lower ATP yield than the full pathway. The expression of the alternative oxidase gene AOX is influenced by stresses such as cold, reactive oxygen species and infection by pathogens, as well as other factors that reduce electron flow through the cytochrome pathway of respiration. Although the benefit conferred by this activity remains uncertain, it may enhance an organism's ability to resist these stresses by maintaining the oxidized state of the upstream electron-transport components, thereby reducing the level of oxidative stress induced by overreduced electron carriers.
Unusually, the bloodstream form of the protozoan parasite Trypanosoma brucei, which is the cause of sleeping sickness, depends entirely on the alternative oxidase pathway for cellular respiration through its electron transport chain. This major metabolic difference between the parasite and its human host has made the T. brucei alternative oxidase an attractive target for drug design. Of the known inhibitors of alternative oxidases, the antibiotic ascofuranone |
https://en.wikipedia.org/wiki/Entropy%20rate | In the mathematical theory of probability, the entropy rate or source information rate of a stochastic process is, informally, the time density of the average information in a stochastic process. For stochastic processes with a countable index, the entropy rate is the limit of the joint entropy of members of the process divided by , as tends to infinity:
when the limit exists. An alternative, related quantity is:
For strongly stationary stochastic processes, . The entropy rate can be thought of as a general property of stochastic sources; this is the asymptotic equipartition property. The entropy rate may be used to estimate the complexity of stochastic processes. It is used in diverse applications ranging from characterizing the complexity of languages, blind source separation, through to optimizing quantizers and data compression algorithms. For example, a maximum entropy rate criterion may be used for feature selection in machine learning.
Entropy rates for Markov chains
Since a stochastic process defined by a Markov chain that is irreducible, aperiodic
and positive recurrent has a stationary distribution, the entropy rate is independent of the initial distribution.
For example, for such a Markov chain defined on a countable number of states, given the transition matrix , is given by:
where is the asymptotic distribution of the chain.
A simple consequence of this definition is that an i.i.d. stochastic process has an entropy rate that is the same as the entropy of any individual member of the process.
See also
Information source (mathematics)
Markov information source
Asymptotic equipartition property
Maximal entropy random walk - chosen to maximize entropy rate |
https://en.wikipedia.org/wiki/Essentials%20of%20Programming%20Languages | Essentials of Programming Languages (EOPL) is a textbook on programming languages by Daniel P. Friedman, Mitchell Wand, and Christopher T. Haynes.
EOPL surveys the principles of programming languages from an operational perspective. It starts with an interpreter in Scheme for a simple functional core language similar to the lambda calculus and then systematically adds constructs. For each addition, for example, variable assignment or thread-like control, the book illustrates an increase in expressive power of the programming language and a demand for new constructs for the formulation of a direct interpreter. The book also demonstrates that systematic transformations, say, store-passing style or continuation-passing style, can eliminate certain constructs from the language in which the interpreter is formulated.
The second part of the book is dedicated to a systematic translation of the interpreter(s) into register machines. The transformations show how to eliminate higher-order closures; continuation objects; recursive function calls; and more. At the end, the reader is left with an "interpreter" that uses nothing but tail-recursive function calls and assignment statements plus conditionals. It becomes trivial to translate this code into a C program or even an assembly program. As a bonus, the book shows how to pre-compute certain pieces of "meaning" and how to generate a representation of these pre-computations. Since this is the essence of compilation, the book also prepares the reader for a course on the principles of compilation and language translation, a related but distinct topic. Apart from the text explaining the key concepts, the book also comprises a series of exercises, enabling the readers to explore alternative designs and other issues.
Like SICP, EOPL represents a significant departure from the prevailing textbook approach in the 1980s. At the time, a book on the principles of programming languages presented four to six (or even more) programming |
https://en.wikipedia.org/wiki/Unisphere%20Networks | Unisphere Networks (formally Unisphere Solutions) was a Westford, Massachusetts-based networking equipment manufacturer and subsidiary of German corporation Siemens AG. Formed in 1998 at a cost of roughly US$1 billion, Unisphere was later sold to Juniper Networks in May 2002 for between $585 million and $740 million, as $375 million in cash and 36.5 million shares of Juniper stock.
Long known for their expertise in the circuit-switched realm of public-switched telephone networks (or PSTNs), Siemens embarked on a market strategy that held, as a primary goal, entry into the North American packet-switched market arena. Unisphere Solutions (changed to Unisphere Networks in late 2000) was an essential element of this strategy as it leveraged existing technology in, at the time, three critical and growing areas of the Internet: edge-networking/BRAS, voice mediation, and core routing.
Following the acquisition of Redstone Communications, CEO and founder James Dolce, joined the Unisphere management team and for a time reported to then Unisphere CEO Martin C. Clague. Dolce replaced Clague in January 2000 when the former was appointed as Unisphere's president and CEO.
Companies/groups that composed Unisphere
Acquisitions
The following acquisitions made up the majority of Unisphere and were distinct BUs within the new company:
Redstone Communications — Specialized in edge-routing and BRAS technology. Their flagship product, the ERX-series (later Juniper's E-series of routers, now EOL), competed against Cisco's 10000 and 7500 series routers as well as the Redback's SMS platform. The ERX was the main compelling reason why Juniper acquired Unisphere in 2002.
Argon Networks — Specialized in core-routing technology meant to compete with Cisco's GSR and Juniper's M and T-series core routers. The Argon product never made it out of R&D and the project was cancelled following the Juniper acquisition.
Castle Networks — Specialized in voice-mediation. The Castle Networks |
https://en.wikipedia.org/wiki/Epistemic%20closure | Epistemic closure is a property of some belief systems. It is the principle that if a subject knows , and knows that entails , then can thereby come to know . Most epistemological theories involve a closure principle and many skeptical arguments assume a closure principle.
On the other hand, some epistemologists, including Robert Nozick, have denied closure principles on the basis of reliabilist accounts of knowledge. Nozick, in Philosophical Explanations, advocated that, when considering the Gettier problem, the least counter-intuitive assumption we give up should be epistemic closure. Nozick suggested a "truth tracking" theory of knowledge, in which the x was said to know P if x's belief in P tracked the truth of P through the relevant modal scenarios.
A subject may not actually believe q, for example, regardless of whether he or she is justified or warranted. Thus, one might instead say that knowledge is closed under known deduction: if, while knowing p, S believes q because S knows that p entails q, then S knows q. An even stronger formulation would be as such: If, while knowing various propositions, S believes p because S knows that these propositions entail p, then S knows p. While the principle of epistemic closure is generally regarded as intuitive, philosophers such as Robert Nozick and Fred Dretske have argued against it.
Epistemic closure and skeptical arguments
The epistemic closure principle typically takes the form of a modus ponens argument:
S knows p.
S knows that p entails q.
Therefore, S knows q.
This epistemic closure principle is central to many versions of skeptical arguments. A skeptical argument of this type will involve knowledge of some piece of widely accepted information to be knowledge, which will then be pointed out to entail knowledge of some skeptical scenario, such as the brain in a vat scenario or the Cartesian evil demon scenario. A skeptic might say, for example, that if you know that you have hands, then you know th |
https://en.wikipedia.org/wiki/Mooring%20%28oceanography%29 | A mooring in oceanography is a collection of devices connected to a wire and anchored on the sea floor. It is the Eulerian way of measuring ocean currents, since a mooring is stationary at a fixed location. In contrast to that, the Lagrangian way measures the motion of an oceanographic drifter, the Lagrangian drifter.
Construction principle
The mooring is held up in the water column with various forms of buoyancy such as glass balls and syntactic foam floats. The attached instrumentation is wide-ranging but often includes CTDs (conductivity, temperature depth sensors), current meters (e.g. acoustic Doppler current profilers or deprecated rotor current meters), and biological sensors to measure various parameters. Long-term moorings can be deployed for durations of two years or more, powered with alkaline or lithium battery packs.
Components
Top buoy
Surface buoys
Moorings often include surface buoys that transmit real time data back to shore. The traditional approach is to use the Argos System. Alternatively, one may use the commercial Iridium satellites which allow higher data rates.
Submerged buoys
In deeper waters, areas covered by sea ice, areas within or near shipping lines or areas that are prone to theft or vandalism, moorings are often submerged with no surface markers. Submerged moorings typically use an acoustic release or a Timed Release that connects the mooring to an anchor weight on the sea floor. The weight is released by sending a coded acoustic command signal and stays on the ground. Deep water anchors are typically made from steel and may be as large as 100 kg. A common deep water anchor consists of a stack of 2–4 railroad wheels. In shallow waters anchors may consist of a concrete block or small portable anchor.
The buoyancy of the floats, i.e. of the top buoy plus additional packs of glass bulbs of foam, is sufficient to carry the instruments back to the surface. In order to avoid entangled ropes, it has been practical to place additional f |
https://en.wikipedia.org/wiki/Dutch%20Maiden | The Dutch Maiden (Dutch: Nederlandse Maagd) is a national personification of the Netherlands. She is typically depicted wearing a Roman garment and with a lion, the Leo Belgicus, by her side. In addition to the symbol of a national maiden, there were also symbolic provincial maidens and town maidens.
The Dutch Maiden has been used as a national symbol since the 16th century. During the Dutch Revolt, a maiden representing the United Provinces of the Netherlands became a recurrent theme in allegorical cartoons. In early depictions she may be shown in the "Garden of Holland", a small garden surrounded by a fence, recalling the medieval hortus conclusus of the Virgin Mary. On 25 May 1694, the States of Holland and West Friesland introduced a uniform coin design for the United Provinces, showing a Dutch Maiden leaning on a bible placed on an altar and holding a lance with the cap of liberty, the Liberty pole.
Initially carrying a martyr's palm, by the late 17th century she often carries a cap of liberty on a liberty pole, though the hat is a conventional male style for the period, rather than the Phrygian cap that later images of liberty personified in other countries used. Alongside the type of depiction with a liberty pole, which is usually costumed in more or less modern styles, images in the Baroque classical dress that was more conventional for such personifications are also found.
19th-century and later
During the French Revolutionary occupation, the short-lived Batavian Republic adopted the Dutch Maiden as its main symbol. The symbol was depicted on the upper left corner of the Batavian Republic's flag, with a lion at her feet. In one hand, she holds a shield with the Roman fasces and in the other a lance crowned with the cap of liberty.
The Dutch Maiden continued to be used as a symbol after the foundation of the Kingdom of the Netherlands in 1815. She was integrated into a number of 19th century monuments, including:
the statue in the centre of Plein |
https://en.wikipedia.org/wiki/C%C3%A9a%27s%20lemma | Céa's lemma is a lemma in mathematics. Introduced by Jean Céa in his Ph.D. dissertation, it is an important tool for proving error estimates for the finite element method applied to elliptic partial differential equations.
Lemma statement
Let be a real Hilbert space with the norm Let be a bilinear form with the properties
for some constant and all in (continuity)
for some constant and all in (coercivity or -ellipticity).
Let be a bounded linear operator. Consider the problem of finding an element in such that
for all in
Consider the same problem on a finite-dimensional subspace of so, in satisfies
for all in
By the Lax–Milgram theorem, each of these problems has exactly one solution. Céa's lemma states that
for all in
That is to say, the subspace solution is "the best" approximation of in up to the constant
The proof is straightforward
for all in
We used the -orthogonality of and
which follows directly from
for all in .
Note: Céa's lemma holds on complex Hilbert spaces also, one then uses a sesquilinear form instead of a bilinear one. The coercivity assumption then becomes for all in (notice the absolute value sign around ).
Error estimate in the energy norm
In many applications, the bilinear form is symmetric, so
for all in
This, together with the above properties of this form, implies that is an inner product on The resulting norm
is called the energy norm, since it corresponds to a physical energy in many problems. This norm is equivalent to the original norm
Using the -orthogonality of and and the Cauchy–Schwarz inequality
for all in .
Hence, in the energy norm, the inequality in Céa's lemma becomes
for all in
(notice that the constant on the right-hand side is no longer present).
This states that the subspace solution is the best approximation to the full-space solution in respect to the energy norm. Geometrically, this means that is the projection of the |
https://en.wikipedia.org/wiki/Freenex | Freenex Co, Ltd. is a Korean company that supplies navigation systems for electronics and automotive applications. It is headquartered in Gil-dong Gangdong-gu Seoul, Korea, established in 2002. Freenex companies develop consumer and aviation technologies employing the Global Positioning System. Freenex also creates OEM products for BMW, Hyundai Autonet, WIA brand navigation automotive markets and for Vitas.
Products include television, navigated teletext, digital maps and navigation. Its primary competitor in Hyundai Autonet and Garmin. Freenex CEO is Lee Woo Yeol (이우열).
Products
L-Vision model:520
H-Vision model:2200, 700
D-Vision model:700, 750, 720G
DM-720CL
DXM-760
DMB-100
Major competitors
Hyundai Autonet
Thinkway
Exroad
Garmin
See also
Automotive navigation system |
https://en.wikipedia.org/wiki/Elixir%20sulfanilamide | Elixir sulfanilamide was an improperly prepared sulfonamide antibiotic that caused mass poisoning in the United States in 1937. It is believed to have killed more than 100 people. The public outcry caused by this incident and other similar disasters led to the passing of the 1938 Federal Food, Drug, and Cosmetic Act, which significantly increased the Food and Drug Administration's powers to regulate drugs.
History
Aside from the Pure Food and Drug Act of 1906 and the Harrison Act of 1914 banning the sale of some narcotic drugs, there was no federal regulatory control in the United States of America for drugs until Congress enacted the 1938 Food, Drug, and Cosmetic Act in response to the elixir sulfanilamide poisonings.
In 1937, S. E. Massengill Company, a pharmaceutical manufacturer, created an oral preparation of sulfanilamide using diethylene glycol (DEG) as the solvent or excipient, and called the preparation "Elixir Sulfanilamide". DEG is poisonous to humans and other mammals, but Harold Watkins, the company's chief pharmacist and chemist, was not aware of this. (Although the first case of a fatality from the related ethylene glycol occurred in 1930 and studies had been published in medical journals stating DEG could cause kidney damage or failure, its toxicity was not widely known prior to the incident.) Watkins simply mixed raspberry flavoring into the powdered drug and then dissolved the mixture in DEG. Animal testing was not required by law, and Massengill performed none; there were no regulations at the time requiring premarket safety testing of drugs.
The company started selling and distributing the medication in September 1937. By October 11, the American Medical Association received a report of several deaths caused by the medication. The Food and Drug Administration was notified, and an extensive search was conducted to recover the distributed medicine. Frances Oldham Kelsey assisted on a research project that verified that the DEG solvent was respo |
https://en.wikipedia.org/wiki/Growing%20Up%20in%20the%20Universe | Growing Up in the Universe was a series of lectures given by Richard Dawkins as part of the Royal Institution Christmas Lectures, in which he discussed the evolution of life in the universe.
The lectures were first broadcast in 1991, in the form of five one-hour episodes, on the BBC in the United Kingdom. The Richard Dawkins Foundation for Reason and Science was granted the rights to the televised lectures, and a DVD version was released by the foundation on 20 April 2007.
Dawkins' book Climbing Mount Improbable developed from the ideas presented in the lectures, and the title itself is taken from the third lecture in the series.
Parts
Part 1: Waking Up in the Universe
To start off part one, Dawkins discusses the amazing capabilities of the human body and contrasts these with the limited capabilities of computers and other man-made machines. He uses a small totem pole (which is used in ancestor worship) to illustrate the importance of studying our ancestors to understand how we've evolved. To contrast ease of reproduction with the difficulty of becoming an ancestor, Dawkins uses the example of paper folding to explain exponential growth. Dawkins then tells the audience that exponential growth does not generally happen in the real world – natural factors come into play which control the population numbers, meaning that only an elite group of organisms will actually become distant ancestors. To be in this elite group, the organism must "have what it takes" to survive and pass on their genes to offspring.
The long chain of successful ancestors means that the probability of our existence is very small, and we are lucky to be alive. By turning down the lights and shining a small spotlight on a large ruler in front of him, Dawkins illustrates the darkness of the distant past and of the unknown future.
After expounding on how lucky we are to be alive, and urging us not to waste the precious time that we have, Dawkins brings up the usefulness of science in aiding our |
https://en.wikipedia.org/wiki/Mallee%20%28habit%29 | Mallee are trees or shrubs, mainly certain species of eucalypts, which grow with multiple stems springing from an underground lignotuber, usually to a height of no more than . The term is widely used for trees with this growth habit across southern Australia, in the states of Western Australia, South Australia, New South Wales and Victoria, and has given rise to other uses of the term, including the ecosystems where such trees predominate, specific geographic areas within some of the states and as part of various species' names.
Etymology
The word is thought to originate from the word mali, meaning water, in the Wemba Wemba language, an Aboriginal Australian language of southern New South Wales and Victoria. The word is also used in the closely related Woiwurrung language and other Aboriginal languages of Victoria, South Australia, and southern New South Wales.
Overview
The term mallee is used describe various species of trees or woody plants, mainly of the genus Eucalyptus, which grow with multiple stems springing from an underground bulbous woody structure called a lignotuber, or mallee root, usually to a height of no more than . The term is widely used for trees with this across southern Australia, across the states of Western Australia, South Australia, New South Wales and Victoria. The term is also applied to other eucalypts with a similar growth habit, in particular those in the closely related genera Corymbia and Angophora.
Some of the species grow as single-stemmed trees initially, but recover in mallee form if burnt to the ground by bushfire.
Over 50 per cent of eucalypt species are mallees, and they are mostly slow-growing and tough. The lignotuber enables the plant to regenerate after fire, wind damage or other type of trauma.
Range
Mallees are the dominant vegetation throughout semi-arid areas of Australia with reliable winter rainfall. Within this area, they form extensive woodlands and shrublands covering over in New South Wales, north-western |
https://en.wikipedia.org/wiki/Mind%E2%80%93body%20problem | The mind–body problem is a philosophical problem concerning the relationship between thought and consciousness in the human mind, and the body.
It is not obvious how the concept of the mind and the concept of the body relate. For example, feelings of sadness (which are mental events) cause people to cry (which is a physical state of the body). Finding a joke funny (a mental event) causes one to laugh (another bodily state). Feelings of pain (in the mind) cause avoidance behaviours (in the body), and so on.
Similarly, changing the chemistry of the body (and the brain especially) via drugs (such as antipsychotics, SSRIs, or alcohol) can change one's state of mind in nontrivial ways. Alternatively, therapeutic interventions like cognitive behavioural therapy can change cognition in ways that have downstream effects on the bodily health.
In general, the existence of these mind–body connections seems unproblematic. Issues arise, however, once one considers what exactly we should make of these relations from a metaphysical or scientific perspective. Such reflections quickly raise a number of questions like:
Are the mind and body two distinct entities, or a single entity?
If the mind and body are two distinct entities, do the two of them causally interact?
Is it possible for these two distinct entities to causally interact?
What is the nature of this interaction?
Can this interaction ever be an object of empirical study?
If the mind and body are a single entity, then are mental events explicable in terms of physical events, or vice versa?
Is the relation between mental and physical events something that arises de novo at a certain point in development?
And so on. These and other questions that discuss the relation between mind and body are questions that all fall under the banner of the 'mind–body problem'.
Mind–body interaction and mental causation
Philosophers David L. Robb and John F. Heil introduce mental causation in terms of the mind–body problem of int |
https://en.wikipedia.org/wiki/Phase%20retrieval | Phase retrieval is the process of algorithmically finding solutions to the phase problem. Given a complex signal , of amplitude , and phase :
where x is an M-dimensional spatial coordinate and k is an M-dimensional spatial frequency coordinate. Phase retrieval consists of finding the phase that satisfies a set of constraints for a measured amplitude. Important applications of phase retrieval include X-ray crystallography, transmission electron microscopy and coherent diffractive imaging, for which . Uniqueness theorems for both 1-D and 2-D cases of the phase retrieval problem, including the phaseless 1-D inverse scattering problem, were proven by Klibanov and his collaborators (see References).
Problem formulation
Here we consider 1-D discrete Fourier transform (DFT) phase retrieval problem. The DFT of a complex signal is given by
,
and the oversampled DFT of is given by
,
where .
Since the DFT operator is bijective, this is equivalent to recovering the phase . It is common recovering a signal from its autocorrelation sequence instead of its Fourier magnitude. That is, denote by the vector after padding with zeros. The autocorrelation sequence of is then defined as
,
and the DFT of , denoted by , satisfies .
Methods
Error reduction algorithm
The error reduction is a generalization of the Gerchberg–Saxton algorithm. It solves for from measurements of by iterating a four-step process. For the th iteration the steps are as follows:
Step (1): , , and are estimates of, respectively, , and . In the first step we calculate the Fourier transform of :
Step (2): The experimental value of , calculated from the diffraction pattern via the signal equation, is then substituted for , giving an estimate of the Fourier transform:
where the ' denotes an intermediate result that will be discarded later on.
Step (3): the estimate of the Fourier transform is then inverse Fourier transformed:
Step (4): then must be changed so that the new estimate of |
https://en.wikipedia.org/wiki/Medical%20statistics | Medical statistics deals with applications of statistics to medicine and the health sciences, including epidemiology, public health, forensic medicine, and clinical research. Medical statistics has been a recognized branch of statistics in the United Kingdom for more than 40 years but the term has not come into general use in North America, where the wider term 'biostatistics' is more commonly used. However, "biostatistics" more commonly connotes all applications of statistics to biology. Medical statistics is a subdiscipline of statistics. "It is the science of summarizing, collecting, presenting and interpreting data in medical practice, and using them to estimate the magnitude of associations and test hypotheses. It has a central role in medical investigations. It not only provides a way of organizing information on a wider and more formal basis than relying on the exchange of anecdotes and personal experience, but also takes into account the intrinsic variation inherent in most biological processes."
Pharmaceutical statistics
Pharmaceutical statistics is the application of statistics to matters concerning the pharmaceutical industry. This can be from issues of design of experiments, to analysis of drug trials, to issues of commercialization of a medicine.
There are many professional bodies concerned with this field including:
European Federation of Statisticians in the Pharmaceutical Industry (EFSPI)
Statisticians In The Pharmaceutical Industry (PSI)
There are also journals including:
Statistics in Medicine
Pharmaceutical Statistics
Clinical biostatistics
Clinical biostatistics is concerned with research into the principles and methodology used in the design and analysis of clinical research and to apply statistical theory to clinical medicine.
There is a society for Clinical Biostatistics with annual conferences since its founding in 1978.
Clinical Biostatistics is taught in postgraduate biostatistical and applied statistical degrees, for example as |
https://en.wikipedia.org/wiki/Penitrem%20A | Penitrem A (tremortin) is an indole-diterpenoid mycotoxin produced by certain species of Aspergillus, Claviceps, and Penicillium, which can be found growing on various plant species such as ryegrass. Penitrem A is one of many secondary metabolites following the synthesis of paxilline in Penicillium crostosum. Penitrem A poisoning in humans and animals usually occurs through the consumption of contaminated foods by mycotoxin-producing species, which is then distributed through the body by the bloodstream. It bypasses the blood-brain barrier to exert its toxicological effects on the central nervous system. In humans, penitrem A poisoning has been associated with severe tremors, hyperthermia, nausea/vomiting, diplopia, and bloody diarrhea. In animals, symptoms of penitrem A poisoning has been associated with symptoms ranging from tremors, seizures, and hyperthermia to ataxia and nystagmus.
Roquefortine C has been commonly detected in documented cases of penitrem A poisoning, making it a possible biomarker for diagnoses.
Mechanism of action
Penitrem A impairs GABAergic amino acid neurotransmission and antagonizes high-conductance Ca2+-activated potassium channels in both humans and animals. Impairment of the GABAergic amino acid neurotransmission comes with the spontaneous release of the excitatory amino acids glutamate and aspartate as well as the inhibitory neurotransmitter γ-aminobutyric acid (GABA). The sudden release of these neurotransmitters results in imbalanced GABAergic signalling, which gives rise to neurological disorders such as the tremors associated with penitrem A poisoning.
Penitrem A also induces the production of reactive oxygen species (ROS) in the neutrophil granulocytes of humans and animals. Increased ROS production results in tissue damage in the brain and other afflicted organs as well as hemorrhages in acute poisonings.
Synthesis
In Penicillium crustosum, synthesis of penitrem A and other secondary metabolites follows the synthesis of pax |
https://en.wikipedia.org/wiki/Horocycle | In hyperbolic geometry, a horocycle (), sometimes called an oricycle, oricircle, or limit circle, is a curve whose normal or perpendicular geodesics all converge asymptotically in the same direction. It is the two-dimensional case of a horosphere (or orisphere).
The centre of a horocycle is the ideal point where all normal geodesics asymptotically converge. Two horocycles who have the same centre are concentric.
Although it appears as if two concentric horocycles cannot have the same length or curvature, in fact any two horocycles are congruent.
A horocycle can also be described as the limit of the circles that share a tangent in a given point, as their radii go towards infinity. In Euclidean geometry, such a "circle of infinite radius" would be a straight line, but in hyperbolic geometry it is a horocycle (a curve).
From the convex side the horocycle is approximated by hypercycles whose distances from their axis go towards infinity.
Properties
Through every pair of points there are 2 horocycles. The centres of the horocycles are the ideal points of the perpendicular bisector of the segment between them.
No three points of a horocycle are on a line, circle or hypercycle.
All horocycles are congruent. (Even concentric horocycles are congruent to each other)
A straight line, circle, hypercycle, or other horocycle cuts a horocycle in at most two points.
The perpendicular bisector of a chord of a horocycle is a normal of that horocycle and the bisector bisects the arc subtended by the chord and is an axis of symmetry of that horocycle.
The length of an arc of a horocycle between two points is:
longer than the length of the line segment between those two points,
longer than the length of the arc of a hypercycle between those two points and
shorter than the length of any circle arc between those two points.
The distance from a horocycle to its center is infinite, and while in some models of hyperbolic geometry it looks like the two "ends" of a horocycle g |
https://en.wikipedia.org/wiki/Gravitational-wave%20observatory | A gravitational-wave detector (used in a gravitational-wave observatory) is any device designed to measure tiny distortions of spacetime called gravitational waves. Since the 1960s, various kinds of gravitational-wave detectors have been built and constantly improved. The present-day generation of laser interferometers has reached the necessary sensitivity to detect gravitational waves from astronomical sources, thus forming the primary tool of gravitational-wave astronomy.
The first direct observation of gravitational waves was made in September 2015 by the Advanced LIGO observatories, detecting gravitational waves with wavelengths of a few thousand kilometers from a merging binary of stellar black holes. In June 2023, four pulsar timing array collaborations presented the first strong evidence for a gravitational wave background of wavelengths spanning light years, most likely from many binaries of supermassive black holes.
Challenge
The direct detection of gravitational waves is complicated by the extraordinarily small effect the waves produce on a detector. The amplitude of a spherical wave falls off as the inverse of the distance from the source. Thus, even waves from extreme systems such as merging binary black holes die out to a very small amplitude by the time they reach the Earth. Astrophysicists predicted that some gravitational waves passing the Earth might produce differential motion on the order 10−18 m in a LIGO-size instrument.
Resonant mass antennas
A simple device to detect the expected wave motion is called a resonant mass antenna – a large, solid body of metal isolated from outside vibrations. This type of instrument was the first type of gravitational-wave detector. Strains in space due to an incident gravitational wave excite the body's resonant frequency and could thus be amplified to detectable levels. Conceivably, a nearby supernova might be strong enough to be seen without resonant amplification. However, up to 2018, no gravitational wave |
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