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They can therefore rely on diffusion across their cell membranes to carry out the gas exchange needed for respiration.In organisms that have circulatory systems associated with their specialized gas-exchange surfaces, a great variety of systems are used for the interaction between the two. In a countercurrent flow system, air (or, more usually, the water containing dissolved air) is drawn in the opposite direction to the flow of blood in the gas exchanger. A countercurrent system such as this maintains a steep concentration gradient along the length of the gas-exchange surface (see lower diagram in Fig. 2). | https://en.wikipedia.org/wiki/Gas_exchange |
This is the situation seen in the gills of fish and many other aquatic creatures. The gas-containing environmental water is drawn unidirectionally across the gas-exchange surface, with the blood-flow in the gill capillaries beneath flowing in the opposite direction. Although this theoretically allows almost complete transfer of a respiratory gas from one side of the exchanger to the other, in fish less than 80% of the oxygen in the water flowing over the gills is generally transferred to the blood.Alternative arrangements are cross current systems found in birds. | https://en.wikipedia.org/wiki/Gas_exchange |
and dead-end air-filled sac systems found in the lungs of mammals. In a cocurrent flow system, the blood and gas (or the fluid containing the gas) move in the same direction through the gas exchanger. This means the magnitude of the gradient is variable along the length of the gas-exchange surface, and the exchange will eventually stop when an equilibrium has been reached (see upper diagram in Fig. 2). Cocurrent flow gas exchange systems are not known to be used in nature. | https://en.wikipedia.org/wiki/Gas_exchange |
In multicellular organisms with dedicated reproductive cells, mutations can be subdivided into germline mutations, which can be passed on to descendants through their reproductive cells, and somatic mutations (also called acquired mutations), which involve cells outside the dedicated reproductive group and which are not usually transmitted to descendants. Diploid organisms (e.g., humans) contain two copies of each gene—a paternal and a maternal allele. Based on the occurrence of mutation on each chromosome, we may classify mutations into three types. A wild type or homozygous non-mutated organism is one in which neither allele is mutated. | https://en.wikipedia.org/wiki/Loss-of-function_mutation |
A heterozygous mutation is a mutation of only one allele. A homozygous mutation is an identical mutation of both the paternal and maternal alleles. Compound heterozygous mutations or a genetic compound consists of two different mutations in the paternal and maternal alleles. | https://en.wikipedia.org/wiki/Loss-of-function_mutation |
In multicellular organisms, stem cells are undifferentiated or partially differentiated cells that can differentiate into various types of cells and proliferate indefinitely to produce more of the same stem cell. They are the earliest type of cell in a cell lineage. They are found in both embryonic and adult organisms, but they have slightly different properties in each. They are usually distinguished from progenitor cells, which cannot divide indefinitely, and precursor or blast cells, which are usually committed to differentiating into one cell type. | https://en.wikipedia.org/wiki/Stem-cell_research |
In mammals, roughly 50–150 cells make up the inner cell mass during the blastocyst stage of embryonic development, around days 5–14. These have stem-cell capability. In vivo, they eventually differentiate into all of the body's cell types (making them pluripotent). | https://en.wikipedia.org/wiki/Stem-cell_research |
This process starts with the differentiation into the three germ layers – the ectoderm, mesoderm and endoderm – at the gastrulation stage. However, when they are isolated and cultured in vitro, they can be kept in the stem-cell stage and are known as embryonic stem cells (ESCs). Adult stem cells are found in a few select locations in the body, known as niches, such as those in the bone marrow or gonads. | https://en.wikipedia.org/wiki/Stem-cell_research |
They exist to replenish rapidly lost cell types and are multipotent or unipotent, meaning they only differentiate into a few cell types or one type of cell. In mammals, they include, among others, hematopoietic stem cells, which replenish blood and immune cells, basal cells, which maintain the skin epithelium, and mesenchymal stem cells, which maintain bone, cartilage, muscle and fat cells. Adult stem cells are a small minority of cells; they are vastly outnumbered by the progenitor cells and terminally differentiated cells that they differentiate into.Research into stem cells grew out of findings by Canadian biologists Ernest McCulloch, James Till and Andrew J. Becker at the University of Toronto and the Ontario Cancer Institute in the 1960s. | https://en.wikipedia.org/wiki/Stem-cell_research |
As of 2016, the only established medical therapy using stem cells is hematopoietic stem cell transplantation, first performed in 1958 by French oncologist Georges Mathé. Since 1998 however, it has been possible to culture and differentiate human embryonic stem cells (in stem-cell lines). The process of isolating these cells has been controversial, because it typically results in the destruction of the embryo. | https://en.wikipedia.org/wiki/Stem-cell_research |
Sources for isolating ESCs have been restricted in some European countries and Canada, but others such as the UK and China have promoted the research. Somatic cell nuclear transfer is a cloning method that can be used to create a cloned embryo for the use of its embryonic stem cells in stem cell therapy. In 2006, a Japanese team led by Shinya Yamanaka discovered a method to convert mature body cells back into stem cells. These were termed induced pluripotent stem cells (iPSCs). | https://en.wikipedia.org/wiki/Stem-cell_research |
In multicellular organisms, worn-out and ineffective cells are dismantled and recycled for the greater good of the whole organism in a process called apoptosis. It is believed that phenoptosis is an evolutionary mechanism that culls out the damaged, aged, infectious, or those in direct competition with their own offspring for the good of the species. Special circumstances need to exist for the "phenoptosis" strategy to be an evolutionarily stable strategy (ESS), let alone the only ESS. Examples of "phenoptosis" given below are really examples of semelpary - a life history with a single reproduction followed by death, which evolves not "for the good of the species" but as the ESS in the conditions of high adult-to-juvenile mortality ratio. | https://en.wikipedia.org/wiki/Phenoptosis |
The elimination of parts detrimental to the organism or individuals detrimental to the species has been deemed "The samurai law of biology" – it is better to die than to be wrong.Stress-induced, acute, or fast phenoptosis is the rapid deterioration of an organism induced by a life event such as breeding. Elimination of the parent provides space for fitter offspring. As a species this has been advantageous particularly to species that die immediately after spawning.Age-induced, soft, or slow phenoptosis is the slow deterioration and death of an organism due to accumulated stresses over long periods of time. | https://en.wikipedia.org/wiki/Phenoptosis |
In short, it has been proposed that aging, heart disease, cancer, and other age related ailments are means of phenoptosis. "Death caused by aging clears the population of ancestors and frees space for progeny carrying new useful traits." It has also been proposed that age provides a selective advantage to brains over brawn. An example made by V. P. Skulachev provides that of two hares, one faster and one smarter, the faster hare may have a selective advantage in youth but as aging occurs and muscles deteriorate it is the smarter hare that now has the selective advantage. | https://en.wikipedia.org/wiki/Phenoptosis |
In multicellular systems the function of each individual cell is impacted by their spatial location and surroundings. Thus, implementation of DBiT-seq to profile both mRNA and protein levels across a tissue in a spatial context could lead to a better understanding of many biological processes. DBiT-seq can be utilized across many different fields such as oncology, developmental biology, and pathology. Use in developmental biology may lead to a better understanding of how organogenesis occurs, and in oncology it may provide more insight into the role of heterogeneity in tumorigenesis and progression. | https://en.wikipedia.org/wiki/Deterministic_Barcoding_in_Tissue_for_Spatial_Omics_Sequencing |
In multichannel scaling (MCS) mode, the MCA records a pulse count-rate over time. Unlike PHA, MCS does not differentiate pulses of different amplitudes. Instead, the MCA records all measured counts in one channel for a set time interval (called the "dwell time"), then switches to the next channel to record the subsequent time interval, and so on. The internal control voltage signal used to switch channels when the dwell time elapses is often available to the experimenter and can be used to trigger changes in the experimental setup. In this arrangement, the MCA acts as an X–Y recorder, observing changes in the count rate as a function of the controlled experimental parameter. For example, a Geiger counter connected to an MCA in MCS mode could be used to record the amount of ionizing radiation emitted by a neutron generator at different voltages. | https://en.wikipedia.org/wiki/Multichannel_analyzer |
In multicolor character mode (160×200 pixels, which most games use) characters have 4×8 pixels (the characters are still approximately square since the pixels are double width) and 4 colors out of 16 colors. Three of the colors are the same for the entire screen (the background color, multicolor 1, and multicolor 2 registers), while the remaining color can be set individually for every such 4×8 pixel area as defined in color RAM. Sprites in multicolor mode (12×21 pixels) have three colors plus transparency: two colors shared among all sprites and one individual. Artists pick shared colors such that the combination with individual colors leads to a colorful impression. | https://en.wikipedia.org/wiki/MOS_Technology_VIC-II |
Some games reload shared colors during the raster interrupt; for example, the game Turrican II's underwater area (which was vertically distinct) has different colors. Others, such as Epyx's Summer Games and COMPUTE! | https://en.wikipedia.org/wiki/MOS_Technology_VIC-II |
's Gazette's Basketball Sam & Ed, overlay two high-resolution sprites to allow two foreground colors to be used without sacrificing horizontal resolution . Of course, this technique reduces the number of available sprites by half. On PAL C64s, the PAL delay line in the monitor or TV which averages the color hue, but not the brightness, of consecutive screen lines can be used to create seven nonstandard colors by alternating screen lines showing two colors of identical brightness. | https://en.wikipedia.org/wiki/MOS_Technology_VIC-II |
There are seven such pairs of colors in the VIC chip. The C64's team did not spend much time on mathematically computing the 16 color palette. Robert Yannes, who was involved with the development of the VIC-II, said: I'm afraid that not nearly as much effort went into the color selection as you think. | https://en.wikipedia.org/wiki/MOS_Technology_VIC-II |
Since we had total control over hue, saturation and luminance, we picked colors that we liked. In order to save space on the chip, though, many of the colors were simply the opposite side of the color wheel from ones that we picked. This allowed us to reuse the existing resistor values, rather than having a completely unique set for each color. Early versions of the VIC-II used in PAL C64s have a different color palette than later revisions.The full palette of sixteen colors is generated based on variations of YPbPr signals as shown below: | https://en.wikipedia.org/wiki/MOS_Technology_VIC-II |
In multifunction or all-in-one printers, fax machines, photocopiers and scanners, an automatic document feeder or ADF is a feature which takes several pages and feeds the paper one page at a time into a scanner or copier, allowing the user to scan, and thereby copy, print, or fax, multiple-page documents without having to manually replace each page. Most copiers allow scanning on the flatbed or platen (the "glass") or through a document feeder. The vast majority of fax machines have an ADF, allowing the unattended sending of multi-page faxes. | https://en.wikipedia.org/wiki/Automatic_document_feeder |
ADF is so ubiquitous in fax machines that some fax machine owners use the machine as a scanner, faxing multi-page documents to themselves. Document feeders are described by speed, in pages per minute or ppm, and capacity, usually in a range from 10 sheets to 200. There are two kinds of document feeders capable of two-sided (duplex) scanning: a reversing automatic document feeder or RADF scans one side of a page, then flips it and scans the other side. | https://en.wikipedia.org/wiki/Automatic_document_feeder |
A duplexing automatic document feeder or DADF scans both sides in one pass. The advantage of the DADF is faster speed for two-sided originals. RADFs and DADFs are rated in images per minute (IPM), the number of sides they can scan each minute; this may depend upon the resolution being used (rather than the maximum resolution supported). | https://en.wikipedia.org/wiki/Automatic_document_feeder |
In multijunction photovoltaic cells, tunnel junctions form the connections between consecutive p-n junctions. They function as an ohmic electrical contact in the middle of a semiconductor device. | https://en.wikipedia.org/wiki/Tunnel_junctions |
In multilevel processor sharing a finite set of thresholds are defined and jobs partitioned according to how much service they have received. The lowest level (containing jobs which have received the least service) has the highest priority and higher levels monotonically decreasing priorities. Within each level an internal discipline is used. == References == | https://en.wikipedia.org/wiki/Processor_sharing |
In multilevel security mode of operation (also called Controlled Security Mode), all users must have: Signed NDA for ALL information on the system. Proper clearance for SOME information on the system. Formal access approval for SOME information on the system. A valid need to know for SOME information on the system.All users can access SOME data, based on their need to know, clearance and formal access approval | https://en.wikipedia.org/wiki/Security_Modes |
In multilinear algebra, a multivector, sometimes called Clifford number, is an element of the exterior algebra Λ(V) of a vector space V. This algebra is graded, associative and alternating, and consists of linear combinations of simple k-vectors (also known as decomposable k-vectors or k-blades) of the form v 1 ∧ ⋯ ∧ v k , {\displaystyle v_{1}\wedge \cdots \wedge v_{k},} where v 1 , … , v k {\displaystyle v_{1},\ldots ,v_{k}} are in V. A k-vector is such a linear combination that is homogeneous of degree k (all terms are k-blades for the same k). Depending on the authors, a "multivector" may be either a k-vector or any element of the exterior algebra (any linear combination of k-blades with potentially differing values of k).In differential geometry, a k-vector is a vector in the exterior algebra of the tangent vector space; that is, it is an antisymmetric tensor obtained by taking linear combinations of the exterior product of k tangent vectors, for some integer k ≥ 0. A differential k-form is a k-vector in the exterior algebra of the dual of the tangent space, which is also the dual of the exterior algebra of the tangent space. For k = 0, 1, 2 and 3, k-vectors are often called respectively scalars, vectors, bivectors and trivectors; they are respectively dual to 0-forms, 1-forms, 2-forms and 3-forms. | https://en.wikipedia.org/wiki/Multivector |
In multilinear algebra, a reshaping of tensors is any bijection between the set of indices of an order- M {\displaystyle M} tensor and the set of indices of an order- L {\displaystyle L} tensor, where L < M {\displaystyle L | https://en.wikipedia.org/wiki/Tensor_reshaping |
In multilinear algebra, a tensor contraction is an operation on a tensor that arises from the natural pairing of a finite-dimensional vector space and its dual. In components, it is expressed as a sum of products of scalar components of the tensor(s) caused by applying the summation convention to a pair of dummy indices that are bound to each other in an expression. The contraction of a single mixed tensor occurs when a pair of literal indices (one a subscript, the other a superscript) of the tensor are set equal to each other and summed over. | https://en.wikipedia.org/wiki/Tensor_contraction |
In Einstein notation this summation is built into the notation. The result is another tensor with order reduced by 2. Tensor contraction can be seen as a generalization of the trace. | https://en.wikipedia.org/wiki/Tensor_contraction |
In multilinear algebra, a tensor decomposition is any scheme for expressing a "data tensor" (M-way array) as a sequence of elementary operations acting on other, often simpler tensors. Many tensor decompositions generalize some matrix decompositions.Tensors are generalizations of matrices to higher dimensions (or rather to higher orders, i.e. the higher number of dimensions) and can consequently be treated as multidimensional fields. The main tensor decompositions are: Tensor rank decomposition; Higher-order singular value decomposition; Tucker decomposition; matrix product states, and operators or tensor trains; Online Tensor Decompositions hierarchical Tucker decomposition; block term decomposition | https://en.wikipedia.org/wiki/Tensor_decomposition |
In multilinear algebra, applying a map that is the tensor product of linear maps to a tensor is called a multilinear multiplication. | https://en.wikipedia.org/wiki/Multilinear_multiplication |
In multilinear algebra, mode-m flattening, also known as matrixizing, matricizing, or unfolding, is an operation that reshapes a multi-way array A {\displaystyle {\mathcal {A}}} into a matrix denoted by A {\displaystyle A_{}} (a two-way array). Matrixizing may be regarded as a generalization of the mathematical concept of vectorizing. | https://en.wikipedia.org/wiki/Mode-k_flattening |
In multilinear algebra, one considers multivariable linear transformations, that is, mappings that are linear in each of a number of different variables. This line of inquiry naturally leads to the idea of the dual space, the vector space V* consisting of linear maps f: V → F where F is the field of scalars. Multilinear maps T: Vn → F can be described via tensor products of elements of V*. If, in addition to vector addition and scalar multiplication, there is a bilinear vector product V × V → V, the vector space is called an algebra; for instance, associative algebras are algebras with an associate vector product (like the algebra of square matrices, or the algebra of polynomials). | https://en.wikipedia.org/wiki/Linear_Algebra |
In multilinear algebra, the higher-order singular value decomposition (HOSVD) of a tensor is a specific orthogonal Tucker decomposition. It may be regarded as one type of generalization of the matrix singular value decomposition. It has applications in computer vision, computer graphics, machine learning, scientific computing, and signal processing. | https://en.wikipedia.org/wiki/Higher-order_singular_value_decomposition |
Some aspects can be traced as far back as F. L. Hitchcock in 1928, but it was L. R. Tucker who developed for third-order tensors the general Tucker decomposition in the 1960s, further advocated by L. De Lathauwer et al. in their Multilinear SVD work that employs the power method, or advocated by Vasilescu and Terzopoulos that developed M-mode SVD a parallel algorithm that employs the matrix SVD. The term higher order singular value decomposition (HOSVD) was coined be DeLathauwer, but the algorithm referred to commonly in the literature as the HOSVD and attributed to either Tucker or DeLathauwer was developed by Vasilescu and Terzopoulos. Robust and L1-norm-based variants of HOSVD have also been proposed. | https://en.wikipedia.org/wiki/Higher-order_singular_value_decomposition |
In multilinear algebra, the tensor rank decomposition or the r a n k − R {\displaystyle rank-R} decomposition of a tensor is the decomposition of a tensor in terms of a sum of minimum R {\displaystyle R} r a n k − 1 {\displaystyle rank-1} tensors. This is an open problem. Canonical polyadic decomposition (CPD) is a variant of the rank decomposition which computes the best fitting K {\displaystyle K} r a n k − 1 {\displaystyle rank-1} terms for a user specified K {\displaystyle K} . | https://en.wikipedia.org/wiki/Canonical_polyadic_decomposition |
The CP decomposition has found some applications in linguistics and chemometrics. The CP rank was introduced by Frank Lauren Hitchcock in 1927 and later rediscovered several times, notably in psychometrics. The CP decomposition is referred to as CANDECOMP, PARAFAC, or CANDECOMP/PARAFAC (CP). PARAFAC2 rank decomposition is yet to explore. Another popular generalization of the matrix SVD known as the higher-order singular value decomposition computes orthonormal mode matrices and has found applications in econometrics, signal processing, computer vision, computer graphics, psychometrics. | https://en.wikipedia.org/wiki/Canonical_polyadic_decomposition |
In multilingual Singapore, dubbing is rare for western programs. English-language programs on the free-to-air terrestrial channels are usually subtitled in Chinese or Malay. Chinese, Malay and Tamil programs (except for news bulletins and other live shows), usually have subtitles in English and the original language during the prime time hours. Dual sound programs, such as Korean and Japanese dramas, offer sound in the original languages with subtitles, Mandarin-dubbed and subtitled, or English-dubbed. | https://en.wikipedia.org/wiki/Dub_localization |
The deliberate policy to encourage Mandarin among citizens made it required by law for programs in other Chinese dialects (Hokkien, Cantonese and Teochew) to be dubbed into Mandarin, with the exception of traditional operas. Cantonese and Hokkien shows from Hong Kong and Taiwan, respectively, are available on VCD and DVD. In a recent development, news bulletins are subtitled into the language of the channel they air on. | https://en.wikipedia.org/wiki/Dub_localization |
In multilingual computer systems, different logical characters may have identical appearances. For example, Unicode character U+0430, Cyrillic small letter a ("а"), can look identical to Unicode character U+0061, Latin small letter a, ("a") which is the lowercase "a" used in English. Hence wikipediа.org (xn--wikipedi-86g.org; the Cyrillic version) instead of wikipedia.org (the Latin version). The problem arises from the different treatment of the characters in the user's mind and the computer's programming. | https://en.wikipedia.org/wiki/IDN_homograph_attack |
From the viewpoint of the user, a Cyrillic "а" within a Latin string is a Latin "a"; there is no difference in the glyphs for these characters in most fonts. However, the computer treats them differently when processing the character string as an identifier. Thus, the user's assumption of a one-to-one correspondence between the visual appearance of a name and the named entity breaks down. | https://en.wikipedia.org/wiki/IDN_homograph_attack |
Internationalized domain names provide a backward-compatible way for domain names to use the full Unicode character set, and this standard is already widely supported. However this system expanded the character repertoire from a few dozen characters in a single alphabet to many thousands of characters in many scripts; this greatly increased the scope for homograph attacks. This opens a rich vein of opportunities for phishing and other varieties of fraud. | https://en.wikipedia.org/wiki/IDN_homograph_attack |
An attacker could register a domain name that looks just like that of a legitimate website, but in which some of the letters have been replaced by homographs in another alphabet. The attacker could then send e-mail messages purporting to come from the original site, but directing people to the bogus site. The spoof site could then record information such as passwords or account details, while passing traffic through to the real site. | https://en.wikipedia.org/wiki/IDN_homograph_attack |
The victims may never notice the difference, until suspicious or criminal activity occurs with their accounts. In December 2001 Evgeniy Gabrilovich and Alex Gontmakher, both from Technion, Israel, published a paper titled "The Homograph Attack", which described an attack that used Unicode URLs to spoof a website URL. To prove the feasibility of this kind of attack, the researchers successfully registered a variant of the domain name microsoft.com which incorporated Cyrillic characters. | https://en.wikipedia.org/wiki/IDN_homograph_attack |
Problems of this kind were anticipated before IDN was introduced, and guidelines were issued to registries to try to avoid or reduce the problem. For example, it was advised that registries only accept characters from the Latin alphabet and that of their own country, not all of Unicode characters, but this advice was neglected by major TLDs.On February 7, 2005, Slashdot reported that this exploit was disclosed by 3ric Johanson at the hacker conference Shmoocon. Web browsers supporting IDNA appeared to direct the URL http://www.pаypal.com/, in which the first a character is replaced by a Cyrillic а, to the site of the well known payment site PayPal, but actually led to a spoofed web site with different content. Popular browsers continued to have problems properly displaying international domain names through April 2017.The following alphabets have characters that can be used for spoofing attacks (please note, these are only the most obvious and common, given artistic license and how much risk the spoofer will take of getting caught; the possibilities are far more numerous than can be listed here): | https://en.wikipedia.org/wiki/IDN_homograph_attack |
In multimode fiber optics, mandrel wrapping is a technique used to preferentially attenuate high-order mode power of a propagating optical signal. Consequently, if the fibre is propagating substantial energy in affected modes, the modal distribution will be changed. A cylindrical rod wrap consists of a specified number turns of fiber on a mandrel of specified size, depending on the fibre characteristics and the desired modal distribution. It has application in optical transmission performance tests, to create a defined mode power distribution or to prevent multimode propagation in single mode fibre. | https://en.wikipedia.org/wiki/Mandrel_wrapping |
If the launch fibre is fully filled ahead of the mandrel wrap, the higher-order modes will be stripped off, leaving only lower-order modes. If the launch fibre is underfilled, for example as a consequence of being energized by a laser diode or edge-emitting LED, there will be no effect on the mode power distribution or loss measurements. In multimode fibre, mandrel wrapping is used to eliminate the effect of "transient loss", the tendency of high order modes to experience higher loss than lower order modes. | https://en.wikipedia.org/wiki/Mandrel_wrapping |
Numerical addition (in decibels) of the measured loss of multiple fibre segments and/or components overestimates the loss of the concatenated set if each segment or component has been measured with a full mode power distribution. In single mode optical fibre measurements, it is used to enforce true single mode propagation at wavelengths near or below the theoretical cutoff wavelength, at which substantial power can exist in a higher order mode group. | https://en.wikipedia.org/wiki/Mandrel_wrapping |
In this use, it is commonly termed a High Order Mode Filter (HOMF). Ultimately, the effect of mandrel wrapping on optical measurements depends on the propagating mode power distribution. An additional loss mechanism has no effect unless power is present in the affected modes. | https://en.wikipedia.org/wiki/Mandrel_wrapping |
In multimode optical fiber with many wavelengths propagating, it is sometimes hard to identify the dispersed wavelength out of all the wavelengths that are present, if there is not yet a service degradation issue. One can compare the present optical power of each wavelength to the designed values and look for differences. After that, the optical fiber is tested end to end. | https://en.wikipedia.org/wiki/Modal_dispersion |
If no loss is found, then most probably there is dispersion with that particular wavelength. Normally engineers start testing the fiber section by section until they reach the affected section; all wavelengths are tested and the affected wavelength produces a loss at the far end of the fiber. One can easily calculate how much of the fiber is affected and replace that part of fiber with a new one. Replacement of optical fiber is only required when there is an intense dispersion and service is being affected; otherwise various methods can be used to compensate for the dispersion. | https://en.wikipedia.org/wiki/Modal_dispersion |
In multipath fading two or more different routes taken by the signal, due to reflections, can cause the signal to cancel out each other at certain locations, and to be stronger in other places (upfade). | https://en.wikipedia.org/wiki/Wireless_terminal |
In multiphase flow in porous media, the relative permeability of a phase is a dimensionless measure of the effective permeability of that phase. It is the ratio of the effective permeability of that phase to the absolute permeability. It can be viewed as an adaptation of Darcy's law to multiphase flow. For two-phase flow in porous media given steady-state conditions, we can write q i = − k i μ i ∇ P i for i = 1 , 2 {\displaystyle q_{i}=-{\frac {k_{i}}{\mu _{i}}}\nabla P_{i}\qquad {\text{for}}\quad i=1,2} where q i {\displaystyle q_{i}} is the flux, ∇ P i {\displaystyle \nabla P_{i}} is the pressure drop, μ i {\displaystyle \mu _{i}} is the viscosity. | https://en.wikipedia.org/wiki/Relative_permeability |
The subscript i {\displaystyle i} indicates that the parameters are for phase i {\displaystyle i} . k i {\displaystyle k_{i}} is here the phase permeability (i.e., the effective permeability of phase i {\displaystyle i} ), as observed through the equation above. Relative permeability, k r i {\displaystyle k_{\mathit {ri}}} , for phase i {\displaystyle i} is then defined from k i = k r i k {\displaystyle k_{i}=k_{\mathit {ri}}k} , as k r i = k i / k {\displaystyle k_{\mathit {ri}}=k_{i}/k} where k {\displaystyle k} is the permeability of the porous medium in single-phase flow, i.e., the absolute permeability. | https://en.wikipedia.org/wiki/Relative_permeability |
Relative permeability must be between zero and one. In applications, relative permeability is often represented as a function of water saturation; however, owing to capillary hysteresis one often resorts to a function or curve measured under drainage and another measured under imbibition. Under this approach, the flow of each phase is inhibited by the presence of the other phases. | https://en.wikipedia.org/wiki/Relative_permeability |
Thus the sum of relative permeabilities over all phases is less than 1. However, apparent relative permeabilities larger than 1 have been obtained since the Darcean approach disregards the viscous coupling effects derived from momentum transfer between the phases (see assumptions below). This coupling could enhance the flow instead of inhibit it. This has been observed in heavy oil petroleum reservoirs when the gas phase flows as bubbles or patches (disconnected). | https://en.wikipedia.org/wiki/Relative_permeability |
In multiphase reactors, the flow regime gives information about the behaviour of the gas phase and its interaction with the continuous liquid phase. The flow regime can vary significantly depending on several factors, including gas and liquid flow rates, geometric aspects of the column (column diameter, column height, sparger type, sparger holes diameter, and eventually, the size of the solid particles) and physical properties of the phases.In the most general case, four flow regimes can be encountered in bubble column reactors: (1) homogeneous or bubbly flow regime, (2) slug flow regime, (3) churn or heterogeneous flow regime, and (4) annular flow regime. The homogeneous flow regime takes place at very low superficial gas velocity and can be divided into mono-dispersed and poly-dispersed homogeneous flow regimes. The former is characterized by a mono-dispersed bubble size distribution, the latter by a poly-dispersed one, according to the change in sign of the lift force. | https://en.wikipedia.org/wiki/Bubble_column_reactor |
Small bubbles with a positive lift coefficient move towards the column wall, and large bubbles with a negative lift coefficient move towards the column center. The heterogeneous flow regime occurs at very high gas velocity and represents a chaotic and unsteady flow pattern, with high liquid recirculation and vigorous mixing. A wide range of bubble sizes is experienced, and the average bubble size is governed by coalescence and breakup phenomena, which determine the flow properties, no longer influenced by the primary bubbles generated at the sparger. | https://en.wikipedia.org/wiki/Bubble_column_reactor |
The slug and the annular flow regimes are usually observed in small-diameter bubble columns with an inner diameter of less than 0.15 m. The former is characterized by giant bubbles, named Taylor bubbles, that occupy the entire cross-sectional area of the column. The latter is characterized by a central core of gas surrounded by a thin liquid film. The annular flow regime exists only at very high gas velocity. | https://en.wikipedia.org/wiki/Bubble_column_reactor |
When dealing with industrial applications, larger-diameter bubble columns are typically employed so that the slug flow regime is not usually observed due to the so-called Rayleight-Taylor instabilities. The quantification of these instabilities at the reactor-scale is obtained by comparing the dimensionless bubble diameter, D H ∗ {\displaystyle D_{H}^{*}} , with a critical diameter, D H , c r ∗ {\displaystyle D_{H,cr}^{*}}: D H ∗ = D H σ / g ( ρ L − ρ G ) > D H , c r ∗ = 52 {\displaystyle D_{H}^{*}={D_{H} \over {\sqrt {\sigma /g(\rho _{L}-\rho _{G})}}}>D_{H,cr}^{*}=52} Where D H {\displaystyle D_{H}} is the bubble column hydraulic diameter, σ {\displaystyle \sigma } is the surface tension, g {\displaystyle g} is the acceleration due to gravity, ρ L {\displaystyle \rho _{L}} is the liquid phase density, and ρ G {\displaystyle \rho _{G}} is the gas phase density. For example, at ambient temperature and pressure and considering air and water as working fluids, a bubble column is classified as a large-diameter if it has a hydraulic diameter greater than 0.15 m.Due to the very high gas velocity, the annular flow regime is not usually observed in industrial bubble columns. Consequently, in a large-scale bubble column, we may have only the bubbly (or homogeneous) and the churn (or heterogenous) flow regimes. Between these flow regimes, a transition region is usually observed, in which the flow field is not as distinct and well defined as in the bubbly-homogeneous and churn-heterogeneous flow regimes.The boundaries between the flow regimes can be graphically observed in the flow regimes map. | https://en.wikipedia.org/wiki/Bubble_column_reactor |
In multiphase systems Relative permeability curves of each fluid phase (i.e., water, oil, gas, CO2) can be averaged using the concept of TEM-function as: | https://en.wikipedia.org/wiki/Relative_permeability |
In multiphase-field models, microstructure is described by set of order parameters, each of which is related to a specific phase or crystallographic orientation. This model is mostly used for solid-state phase transformations where multiple grains evolve (e.g. grain growth, recrystallization or first-order transformation like austenite to ferrite in ferrous alloys). Besides allowing the description of multiple grains in a microstructure, multiphase-field models especially allow for consideration of multiple thermodynamic phases occurring e.g. in technical alloy grades. | https://en.wikipedia.org/wiki/Phase_field_models |
In multiphysics systems—systems involving multiple physical fields that interact with one another—linearization with respect to each of the physical fields may be performed. This linearization of the system with respect to each of the fields results in a linearized monolithic equation system that can be solved using monolithic iterative solution procedures such as the Newton–Raphson method. Examples of this include MRI scanner systems which results in a system of electromagnetic, mechanical and acoustic fields. | https://en.wikipedia.org/wiki/Linearization |
In multiplayer video games, matchmaking is the process of connecting players together for online play sessions. | https://en.wikipedia.org/wiki/Game_server_browser |
In multiplayer video games, particularly in MOBAs, first-person shooters, MMORPGs and MUDs, kill stealing is the practice of obtaining credit for killing an enemy when another player has put more effort into the kill. This usually happens when a game only keeps track of which player defeats an enemy, rather than which player dealt the most damage, leading to the so-called last-hitting mechanics. If one player whittles down some enemy's health points, but a different player eventually finishes the enemy off, this second player might obtain all of the loot or experience points from the enemy. | https://en.wikipedia.org/wiki/Kill_stealing |
Kill stealing is common when the rewards for finishing enemies off are highly desired within the game. Some players feel that kill stealing is a dishonorable practice. A good faith attempt to secure a kill on an enemy that might otherwise have gotten away can sometimes be perceived as a kill steal if the other player believes the kill was already certain. | https://en.wikipedia.org/wiki/Kill_stealing |
In multiplayer, a first in the series, gameplay has an emphasis on teamwork. Lara is able to use Totec's shield as a portable platform as he holds it above his head. She may also balance on spears that Totec throws in the wall, but Totec cannot, as they are not able to hold his weight. Totec can tightrope walk using Lara's grappling rope. | https://en.wikipedia.org/wiki/Lara_Croft_and_the_Guardian_of_Light |
As the game progresses, Totec learns from Lara how to use modern weapons, such as rifles. When enemies are killed, point scores appear above their bodies—red or blue—depending on whether Lara (red) or Totec (blue) scored the kill. There are pick-ups, such as gems, scattered throughout the levels that increase the player's score. | https://en.wikipedia.org/wiki/Lara_Croft_and_the_Guardian_of_Light |
Receiving high scores in each level rewards the players with new weapons and upgrades. To add competitiveness into the game, there are a limited number of enemies and gems in the world so the players may compete to kill and grab them all. The multiplayer mode reportedly features approximately six to eight hours of gameplay, depending on teamwork. | https://en.wikipedia.org/wiki/Lara_Croft_and_the_Guardian_of_Light |
In multiple American and international studies, cancer-causing chemicals have been found in the blood of umbilical cords. These originate from certain plastics, computer circuit boards, fumes and synthetic fragrances among others. Over 300 chemical toxicants have been found, including bisphenol A (BPA), tetrabromobisphenol A (TBBPA), Teflon-related perfluorooctanoic acid, galaxolide and synthetic musks among others. The studies in America showed higher levels in African Americans, Hispanic Americans and Asian Americans due, it is thought, to living in areas of higher pollution. | https://en.wikipedia.org/wiki/Umbilical_cord_knot |
In multiple countries home economists have contributed in strengthening these programs aimed at women, families, and children. These programs aim to teach women formally and informally education, increase understanding and appreciation of other cultures, improving public health, and improving the process of introducing change.A few professional organizations have facilitated international involvement. Some of these include the International Federation of Home Economics (IFHE), American Home Economics Association now the American Association of Family and Consumer Sciences (AAFCS), and the American Association of State Universities and Land Grant Colleges (AASULGC) now the National Association of State Universities and Land-Grant Colleges (NASULGC).Economists in the United States become more involved outside their country around the twentieth century when mission boards hired graduates to assist in establishing home economics departments in other countries to improve living conditions of the people. In the United States, a few states have set up consumer education programs that aim at educating future populations. Texas Office of Consumer Credit Consumer aims to educate Texans to be financially literate and to make good decisions as a consumer.In Australia, consumer education starts in years 9 and 10 as an elective course during their educational career. | https://en.wikipedia.org/wiki/Consumer_education |
In multiple countries rape is defined with penetrative sex, which means that by law, men cannot be raped as they are being forced to penetrate. This includes New Zealand, England and Wales, the Philippines, and Switzerland. | https://en.wikipedia.org/wiki/Discrimination_against_men |
In multiple countries' curriculums, social studies is the integrated study of multiple fields of social science and the humanities, including history, culture, geography and political science. The term was first coined by American educators around the turn of the twentieth century as a catch-all for these subjects, as well as others which did not fit into the helps the models of lower education in the United States, such as philosophy and psychology. One of the purposes of social studies, particularly at the level of higher education, is to integrate several disciplines, with their unique methodologies and special focuses of concentration, into a coherent field of subject areas that communicate with each other by sharing different academic "tools" and perspectives for deeper analysis of social problems and issues. Social studies aims to train students for informed, responsible participation in a diverse democratic society. The content of social studies provides the necessary background knowledge in order to develop values and reasoned opinions, and the objective of the field is civic competence.Human Society and Its Environment (HSIE) is a similar term used in the education system of the Australian state of New South Wales. | https://en.wikipedia.org/wiki/Social_studies |
In multiple criteria decision aiding (MCDA), multicriteria classification (or sorting) involves problems where a finite set of alternative actions should be assigned into a predefined set of preferentially ordered categories (classes). For example, credit analysts classify loan applications into risk categories (e.g., acceptable/unacceptable applicants), customers rate products and classify them into attractiveness groups, candidates for a job position are evaluated and their applications are approved or rejected, technical systems are prioritized for inspection on the basis of their failure risk, clinicians classify patients according to the extent to which they have a complex disease or not, etc. | https://en.wikipedia.org/wiki/Multicriteria_classification |
In multiple electrode aggregometry, anticoagulated whole blood is mixed with saline and a platelet agonist in a single-use cuvette with two pairs of electrodes. The increase in impedance between the electrodes as platelets aggregate onto them, is measured and visualized as a curve. | https://en.wikipedia.org/wiki/Blood_platelet |
In multiple myeloma, genetic analyzes of the tumor is used to detect risks markers such as specific mutation, deletion, insertion etc. Helping to assess the Prognosis of the patient. But there is a discrepancy between patients, some patients associated with a good risk will relapse earlier than expected. In addition, in some patients, risks anomaly will only be observed at relapse. A study from 2023 using single cell showed that subclones with risks marker are present in some patients from the diagnosis but in such low frequency that they are not detectable by standard genetic routine assessment. | https://en.wikipedia.org/wiki/Tumour_heterogeneity |
Furthermore, this study indicated that patients with risks markers detectable only at relapse are indeed associated with a bad prognosis. With some risk anomaly there is no difference in the life expectancy (overall survival) between patients with the anomaly detected from the diagnosis and those with the anomaly only detected at relapse. | https://en.wikipedia.org/wiki/Tumour_heterogeneity |
Open question remains about the effect of the treatment on clonal selection. The therapeutic implication of this result is extensively developed in a paper: "Thus, sensitive detection approaches are required to detect these subclones at diagnosis together with innovative treatment strategies to eradicate low-frequency, high-risk subclones and prevent them from becoming dominant. Finally, the described phenomenon is highly unlikely to be restricted to MM" (Multiple Myeloma). | https://en.wikipedia.org/wiki/Tumour_heterogeneity |
In multiple myeloma, staging helps with prognostication but does not guide treatment decisions. The Durie-Salmon staging system was used historically and was replaced by the International Staging System (ISS), published by the International Myeloma Working Group In 2005. The revised ISS (R-ISS) was published in 2015 and incorporates cytogenetics and lactate dehydrogenase (LDH). : 1730–1: 732–3 Stage I: β2 microglobulin (β2M) < 3.5 mg/L, albumin ≥ 3.5 g/dL, normal cytogenetics, no elevated LDH Stage II: Not classified under Stage I or Stage III Stage III: β2M ≥ 5.5 mg/L and either elevated LDH or high-risk cytogenetics | https://en.wikipedia.org/wiki/Multiple_myeloma |
In multiple pregnancies, which often result from use of assisted reproductive technology, there is a high risk of preterm birth. Selective reduction is used to reduce the number of fetuses to two or three. | https://en.wikipedia.org/wiki/Premature_birth |
In multiple recorded interviews under somewhat casual circumstances, comparing the conflagrations of World War I and II to the ongoing lower-intensity wars of the 21st century, Pope Francis has said, "The world is at war because it has lost the peace", and "perhaps one can speak of a third war, one fought piecemeal". | https://en.wikipedia.org/wiki/World_War_III |
In multiple regression, the omnibus test is an ANOVA F test on all the coefficients, that is equivalent to the multiple correlations R Square F test. The omnibus F test is an overall test that examines model fit, thus failure to reject the null hypothesis implies that the suggested linear model is not significantly suitable to the data. None of the independent variables has explored as significant in explaining the dependent variable variation. These hypotheses examine model fit of the most common model: yi = β0 + β1 xi1 + ... +βk xik + εijestimated by E(yi|xi1,...,xik) = β0 + β1xi1 + ... + βkxik, where E(yi|xi1....xik) is the dependant variable explanatory for the i-th observation, xij is the j-th independent (explanatory) variable, βj is the j-th coefficient of xij and indicates its influence on the dependant variable y upon its partial correlation with y. The F statistics of the omnibus test is: Whereas, ȳ is the overall sample mean for yi, ŷi is the regression estimated mean for specific set of k independent (explanatory) variables and n is the sample size. The F statistic is distributed F (k,n-k-1),(α) under assuming of null hypothesis and normality assumption. | https://en.wikipedia.org/wiki/Omnibus_test |
In multiple sclerosis (MS), the VLA-4 integrin is essential in the processes by which T-cells gain access to the brain. It allows the cells to penetrate the blood brain barrier that normally restricts immune cell access. It has been found that the severity of MS is positively correlated with the expression of alpha 4. | https://en.wikipedia.org/wiki/Integrin_alpha4beta1 |
One approach to prevent an autoimmune reaction has been to block the action of VLA-4 (as with natalizumab) so that pathogenic T-cells are unable to enter the brain and thus unable to attack myelin protein. It has been found that in mice, anti-alpha 4 integrin antibodies resulted in an increase of circulating stem cell and progenitor cells. Though this failed in initial multiple sclerosis research, it is still being investigated. | https://en.wikipedia.org/wiki/Integrin_alpha4beta1 |
In multiple sclerosis, inflammation, demyelination, and neurodegeneration are observed together. Some clinical trials have shown that the inflammation produces both the relapses and the demyelination, and that neurodegeneration (axonal transection) is independent from inflammation, produces the accumulative disability, and advances even when inflammation and demyelination are delayed. It seems that neurodegeneration is produced by damaged mitochondria, which in turn comes from activated microglia.Currently it is unknown what the primary cause of MS is; if MS is a heterogeneous disease, the lesion development process would not be unique. | https://en.wikipedia.org/wiki/Pathophysiology_of_multiple_sclerosis |
In particular, some PPMS patients having a special clinical course named rapidly progressive multiple sclerosis could have a special genetic cause and a different development process. Several types of damage appear in the brain: normal appearing white matter (NAWM) and characteristic lesions. Changes in NAWM include axonal injury without demyelination, low-grade inflammation, and microglial and astrocytic activation | https://en.wikipedia.org/wiki/Pathophysiology_of_multiple_sclerosis |
In multiple sequence alignment, the purpose is to align all sequences to a common reference. However, this common reference is usually unknown. In addition, there is also structural information among the sequences. | https://en.wikipedia.org/wiki/Graphical_time_warping |
Though GTW cannot be directly applied in these applications, a two-stage framework called ncGTW was built upon GTW to solve this problem. In the first stage, the prior structural knowledge among the sequences is utilized to obtain the warping functions. In the second stage, these warping functions help to jointly align all sequences to a virtual reference, which does not need to be explicitly specified. ncGTW was applied to LC-MS profile alignment problems in proteomics data and performed better than existing approaches. | https://en.wikipedia.org/wiki/Graphical_time_warping |
In multiple studies, GHB has been found to impair spatial memory, working memory, learning and memory in rats with chronic administration. These effects are associated with decreased NMDA receptor expression in the cerebral cortex and possibly other areas as well. In addition, the neurotoxicity appears to be caused by oxidative stress. | https://en.wikipedia.org/wiki/GHB_overdose |
In multiple tests of the same hypothesis, the probability of the occurrence of falses positives (familywise error rate) increase and some strategy are used to control this occurrence. This is commonly achieved by using a more stringent threshold to reject null hypotheses. The Bonferroni correction defines an acceptable global significance level, denoted by α* and each test is individually compared with a value of α = α*/m. This ensures that the familywise error rate in all m tests, is less than or equal to α*. | https://en.wikipedia.org/wiki/Biostatistics |
When m is large, the Bonferroni correction may be overly conservative. An alternative to the Bonferroni correction is to control the false discovery rate (FDR). The FDR controls the expected proportion of the rejected null hypotheses (the so-called discoveries) that are false (incorrect rejections). This procedure ensures that, for independent tests, the false discovery rate is at most q*. Thus, the FDR is less conservative than the Bonferroni correction and have more power, at the cost of more false positives. | https://en.wikipedia.org/wiki/Biostatistics |
In multiprocessing, omega networks may be used as connectors between the CPUs and their shared memory, in order to decrease the probability that the CPU-to-memory connection becomes a bottleneck. This class of networks has been built into the Illinois Cedar Multiprocessor, into the IBM RP3, and into the NYU Ultracomputer. | https://en.wikipedia.org/wiki/Omega_network |
In multiprocessing, the processors can be used to execute a single sequence of instructions in multiple contexts (single instruction, multiple data or SIMD, often used in vector processing), multiple sequences of instructions in a single context (multiple instruction, single data or MISD, used for redundancy in fail-safe systems and sometimes applied to describe pipelined processors or hyper-threading), or multiple sequences of instructions in multiple contexts (multiple instruction, multiple data or MIMD). | https://en.wikipedia.org/wiki/Multicore_programming |
In multiprocessor computer systems, software lockout is the issue of performance degradation due to the idle wait times spent by the CPUs in kernel-level critical sections. Software lockout is the major cause of scalability degradation in a multiprocessor system, posing a limit on the maximum useful number of processors. To mitigate the phenomenon, the kernel must be designed to have its critical sections as short as possible, therefore decomposing each data structure in smaller substructures. | https://en.wikipedia.org/wiki/Software_lockout |
In multiprocessor systems, a processor may send an interrupt request to another processor via inter-processor interrupts (IPI). | https://en.wikipedia.org/wiki/Level_triggered_interrupt |
In multisensory integration research, Point of Subjective Simultaneity (PSS), typically measured in milliseconds, is defined as the stimulus onset asynchrony (SOA) at which a pair of signals from different sensory modalities is perceived as most simultaneous or synchronous. In other words, at PSS, an individual is most likely to integrate information from a pair of signals in the two given modalities. | https://en.wikipedia.org/wiki/Point_of_subjective_simultaneity |
In multitasking computer operating systems, a daemon ( or ) is a computer program that runs as a background process, rather than being under the direct control of an interactive user. Traditionally, the process names of a daemon end with the letter d, for clarification that the process is in fact a daemon, and for differentiation between a daemon and a normal computer program. For example, syslogd is a daemon that implements system logging facility, and sshd is a daemon that serves incoming SSH connections. In a Unix environment, the parent process of a daemon is often, but not always, the init process. | https://en.wikipedia.org/wiki/Operating_system_service_management |
A daemon is usually created either by a process forking a child process and then immediately exiting, thus causing init to adopt the child process, or by the init process directly launching the daemon. In addition, a daemon launched by forking and exiting typically must perform other operations, such as dissociating the process from any controlling terminal (tty). | https://en.wikipedia.org/wiki/Operating_system_service_management |
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