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Ellipsoidal method History Ellipsoidal_method > History The ellipsoid method has a long history. As an iterative method, a preliminary version was introduced by Naum Z. Shor. In 1972, an approximation algorithm for real convex minimization was studied by Arkadi Nemirovski and David B. Yudin (Judin). As an algorithm for solving linear programming problems with rational data, the ellipsoid algorithm was studied by Leonid Khachiyan; Khachiyan's achievement was to prove the polynomial-time solvability of linear programs.
Mir-278 microRNA precursor family Summary Mir-278_microRNA_precursor_family In molecular biology mir-278 microRNA is a short RNA molecule belonging to a class of molecules referred to as microRNAs. These function to regulate the expression levels of other genes by several mechanisms, primarily binding to their target at its 3'UTR.
Wind energy software Turbine design Wind_energy_software > Turbine design Easily coupled with other simulation environments such as Simulink and Dymola, it is suitable for aerodynamic optimization, fluid-structure interaction problems, and unsteady control system simulation. Ashes is a software package for analyzing aerodynamic and mechanical forces for onshore and offshore horizontal axis wind turbines. It is based on research done at the Norwegian University of Science and Technology in Trondheim, Norway.
Work of breathing Variations and management of work of breathing Work_of_breathing > Work of breathing in ambient pressure diving > Variations and management of work of breathing Maximum voluntary ventilation is approximated by a square root function of gas density. Exhalation flow rate is limited by effort independent turbulent flow. Once this occurs further attempts to increase flow rate are actively counterproductive and contribute to further accumulation of carbon dioxide. The effects of negative static lung load are amplified by increased gas density.To reduce risk of hypercapnia, divers may adopt a breathing pattern that is slower and deeper than normal rather than fast and shallow, as this gives maximum gas exchange per unit effort by minimising turbulence, friction, and dead space effects.
Boron porphyrins Hydrolysis Boron_porphyrins > Reactivity > Hydrolysis DFT computations show that hydrolysis, as in the scheme shown here, is energetically favorable (breaking of a relatively weak B-C bond, formation of a strong B-O bond, formation of benzene). However, only one of the two phenyl groups is observed to undergo hydrolysis. This suggests thermodynamic favorability is not the only factor at play. Rather, as Belcher et al. suggest, there is a significant steric component to this reaction. The boron in the porphyrin ring plane undergoes substitution, while the out-of-plane boron retains its phenyl bond.
Theoretical incommensurability Introduction of the term Theoretical_incommensurability > Introduction of the term These include the famous thesis on the accumulation of scientific knowledge, which states that the body of scientific knowledge has been increasing with the passage of time. Both Kuhn and Feyerabend reject this thesis, in favor of a model that sees both revolutions and periods of normalcy in the history of science. Another equally important thesis proposes the existence of a neutral language of comparison which can be used to formulate the empirical consequences of two competing theories.
Resource economics Background and introduction Natural_resource_economics > Perpetual resources vs. exhaustibility > Background and introduction An important way of replacing a resource is by synthesis, for example, industrial diamonds and many kinds of graphite, although a certain kind of graphite could be almost replaced by a recycled product. Most graphite is synthetic, for example, graphite electrodes, graphite fiber, graphite shapes (machined or unmachined), and graphite powder. Another way of replacing or extending a resource is by recycling the material desired from scrap or waste.
Software user documentation Composing user documentation Code_documentation > User documentation > Composing user documentation Like other forms of technical documentation, good user documentation benefits from an organized process of development. In the case of user documentation, the process as it commonly occurs in industry consists of five steps: User analysis, the basic research phase of the process. Planning, or the actual documentation phase. Draft review, a self-explanatory phase where feedback is sought on the draft composed in the previous step. Usability testing, whereby the usability of the document is tested empirically. Editing, the final step in which the information collected in steps three and four is used to produce the final draft.
Primary aldosteronism Genetics Conn_syndrome > Causes > Genetics 40% of people with an adrenal aldosterone producing adenoma have somatic gain-of-function mutations in a single gene (KCNJ5). This gene is mutated in inherited cases of early onset primary aldosteronism and bilateral adrenal hyperplasia, albeit less frequently. These mutations tend to occur in young women with the adenoma in the cortisol secreting zona fasciculata. Adenomas without this mutation tend to occur in older men with resistant hypertension.Other genes commonly mutated in aldosterone producing adenomas are ATP1A1 ATP2B3, CACNA1D, and CTNNB1.
Turbulent forces Onset of turbulence Turbulent_forces > Onset of turbulence Counteracting this effect is the viscosity of the fluid, which as it increases, progressively inhibits turbulence, as more kinetic energy is absorbed by a more viscous fluid. The Reynolds number quantifies the relative importance of these two types of forces for given flow conditions, and is a guide to when turbulent flow will occur in a particular situation.This ability to predict the onset of turbulent flow is an important design tool for equipment such as piping systems or aircraft wings, but the Reynolds number is also used in scaling of fluid dynamics problems, and is used to determine dynamic similitude between two different cases of fluid flow, such as between a model aircraft, and its full size version. Such scaling is not always linear and the application of Reynolds numbers to both situations allows scaling factors to be developed.
Protein trafficking Mitochondrial intermembrane space Protein_targeting_system > Sorting of proteins > Mitochondria > Mitochondrial intermembrane space If instead the precursor protein is designated to the intermembrane space of the mitochondrion, there are two pathways this may occur depending on the sequences being recognized. The first pathway to the intermembrane space follows the same steps for an inner membrane targeted protein. However, once bound to the inner membrane the C-terminus of the anchored protein is cleaved via a peptidase that liberates the preprotein into the intermembrane space so it can fold into its active state. One of the greatest examples for a protein that follows this pathway is cytochrome b2, that upon being cleaved will interact with a heme cofactor and become active.
Anisotropic diffusion Regularization Diffusion-based_image_processing > Regularization In this approach, the unknown is convolved with a Gaussian inside the non-linearity to obtain a modified Perona–Malik equation ∂ I ∂ t = div ⁡ ( c ( | ∇ ( G σ ∗ I ) | 2 ) ∇ I ) {\displaystyle {\frac {\partial I}{\partial t}}=\operatorname {div} \left(c(|\nabla (G_{\sigma }*I)|^{2})\nabla I\right)} where G σ = C σ − 1 / 2 exp ⁡ ( − | x | 2 / 4 σ ) {\displaystyle G_{\sigma }=C\sigma ^{-1/2}\exp \left(-|x|^{2}/4\sigma \right)} . The well-posedness of the equation can be achieved by this regularization but it also introduces blurring effect, which is the main drawback of regularization. A prior knowledge of noise level is required as the choice of regularization parameter depends on it.
Binary number system Representation Binary_notation > Representation Any number can be represented by a sequence of bits (binary digits), which in turn may be represented by any mechanism capable of being in two mutually exclusive states. Any of the following rows of symbols can be interpreted as the binary numeric value of 667: The numeric value represented in each case is dependent upon the value assigned to each symbol. In the earlier days of computing, switches, punched holes and punched paper tapes were used to represent binary values. In a modern computer, the numeric values may be represented by two different voltages; on a magnetic disk, magnetic polarities may be used.
Attack patterns Structure Attack_patterns > Structure For example, for the attacker to be able to execute an Integer Overflow attack, they must have access to the vulnerable application. That will be common amongst most of the attacks. However, if the vulnerability only exposes itself when the target is running on a remote RPC server, that would also be a condition that would be noted here.
Wallerian degeneration Myelin clearance Wallerian_degeneration > Myelin clearance PNS is much faster and efficient at clearing myelin debris in comparison to CNS, and Schwann cells are the primary cause of this difference. Another key aspect is the change in permeability of the blood-tissue barrier in the two systems. In PNS, the permeability increases throughout the distal stump, but the barrier disruption in CNS is limited to just the site of injury.
Network neuroscience Modularity Network_neuroscience > Analyzing brain networks > Key components of network analysis > Clustering coefficients and motifs > Modularity Many complex networks consist of a number of modules. There are various algorithms that estimate the modularity of a network, and one of the widely utilized algorithms is based on hierarchical clustering. Each module contains several densely interconnected nodes, and there are relatively few connections between nodes in different modules. Hubs can therefore be described in terms of their roles in this community structure. Provincial hubs are connected mainly to nodes in their own modules, whereas connector hubs are connected to nodes in other modules.
Configuration systems Variants Product_Configurator > Variants Pine (1992) described four types of mass customization: Collaborative customization (also considered co-creation) – Firms talk to individual customers to determine the precise product offering that best serves the customer's needs (see personalized marketing and personal marketing orientation). This information is then used to specify and manufacture a product that suits that specific customer. For example, some clothing companies will manufacture pants or jackets to fit an individual customer. This is also being taken into deeper customization via 3D printing with companies like Shapeways.
Alternatives to Darwinian evolution Genetic drift Alternatives_to_Darwinian_evolution > Alternative explanations of change > Genetic drift The neutral theory of molecular evolution, proposed by Motoo Kimura in 1968, holds that at the molecular level most evolutionary changes and most of the variation within and between species is not caused by natural selection but by genetic drift of mutant alleles that are neutral. A neutral mutation is one that does not affect an organism's ability to survive and reproduce. The neutral theory allows for the possibility that most mutations are deleterious, but holds that because these are rapidly purged by natural selection, they do not make significant contributions to variation within and between species at the molecular level. Mutations that are not deleterious are assumed to be mostly neutral rather than beneficial.The theory was controversial as it sounded like a challenge to Darwinian evolution; controversy was intensified by a 1969 paper by Jack Lester King and Thomas H. Jukes, provocatively but misleadingly titled "Non-Darwinian Evolution". It provided a wide variety of evidence including protein sequence comparisons, studies of the Treffers mutator gene in E. coli, analysis of the genetic code, and comparative immunology, to argue that most protein evolution is due to neutral mutations and genetic drift.According to Kimura, the theory applies only for evolution at the molecular level, while phenotypic evolution is controlled by natural selection, so the neutral theory does not constitute a true alternative.
Antagonism (chemistry) Summary Antagonism_(chemistry) The word is most commonly used in this context in biochemistry and toxicology: interference in the physiological action of a chemical substance by another having a similar structure. For instance, a receptor antagonist is an agent that reduces the response that a ligand produces when the receptor antagonist binds to a receptor on a cell. An example of this is the interleukin-1 receptor antagonist.
Differential and integral calculus Limits and infinitesimals Differential_and_integral_calculus > Principles > Limits and infinitesimals Calculus is usually developed by working with very small quantities. Historically, the first method of doing so was by infinitesimals. These are objects which can be treated like real numbers but which are, in some sense, "infinitely small". For example, an infinitesimal number could be greater than 0, but less than any number in the sequence 1, 1/2, 1/3, ... and thus less than any positive real number.
Thermal entrance length Boundary layer Thermal_entrance_length > Hydrodynamic entrance length > Boundary layer The irrotational (core) flow region: The region in which viscous effects and velocity changes are negligible, also known as the inviscid core.When the fluid just enters the pipe, the thickness of the boundary layer gradually increases from zero moving in the direction of fluid flow and eventually reaches the pipe center and fills the entire pipe. This region from the entrance of the pipe to the point where the boundary layer covers the entire pipe is termed as the hydrodynamic entrance region and the length of the pipe in this region is termed as the hydrodynamic entry length. In this region, the velocity profile develops and thus the flow is called the hydrodynamically developing flow.
Chain Rule Summary Chain_Rule In calculus, the chain rule is a formula that expresses the derivative of the composition of two differentiable functions f and g in terms of the derivatives of f and g. More precisely, if h = f ∘ g {\displaystyle h=f\circ g} is the function such that h ( x ) = f ( g ( x ) ) {\displaystyle h(x)=f(g(x))} for every x, then the chain rule is, in Lagrange's notation, h ′ ( x ) = f ′ ( g ( x ) ) g ′ ( x ) . {\displaystyle h'(x)=f'(g(x))g'(x).} or, equivalently, h ′ = ( f ∘ g ) ′ = ( f ′ ∘ g ) ⋅ g ′ . {\displaystyle h'=(f\circ g)'=(f'\circ g)\cdot g'.}
Two-dimensional manifold Differentiable manifolds Manifold > Additional structure > Differentiable manifolds For most applications, a special kind of topological manifold, namely, a differentiable manifold, is used. If the local charts on a manifold are compatible in a certain sense, one can define directions, tangent spaces, and differentiable functions on that manifold. In particular it is possible to use calculus on a differentiable manifold.
Vector triple product Scalar or pseudoscalar Triple_scalar_product > Scalar triple product > Scalar or pseudoscalar The dot product of two vectors is a scalar but the dot product of a pseudovector and a vector is a pseudoscalar, so the scalar triple product must be pseudoscalar-valued. If T is a rotation operator, then T a ⋅ ( T b × T c ) = a ⋅ ( b × c ) , {\displaystyle \mathbf {Ta} \cdot (\mathbf {Tb} \times \mathbf {Tc} )=\mathbf {a} \cdot (\mathbf {b} \times \mathbf {c} ),} but if T is an improper rotation, then T a ⋅ ( T b × T c ) = − a ⋅ ( b × c ) . {\displaystyle \mathbf {Ta} \cdot (\mathbf {Tb} \times \mathbf {Tc} )=-\mathbf {a} \cdot (\mathbf {b} \times \mathbf {c} ).}
Carbohydrate NMR Carbohydrate NMR databases and tools Carbohydrate_NMR > Carbohydrate NMR databases and tools contains: chemical shift database, empirical spectra simulation routine optimized for carbohydrates, online interface. structure matching tool. Both proton and carbon C and H chemical shifts can be used to access structural information.
Orbiting Carbon Observatory Technology Orbiting_Carbon_Observatory > Technology OCO's spectrometers measure the fraction of the light absorbed in each of these lines with very high precision. This information was then to be analyzed to determine the number of molecules along the path between the top of the atmosphere and the surface. If the amount of carbon dioxide varies from place to place, the amount of absorption will also vary.
Method of moments (electromagnetics) Summary Method_of_moments_(electromagnetics) The method of moments (MoM), also known as the moment method and method of weighted residuals, is a numerical method in computational electromagnetics. It is used in computer programs that simulate the interaction of electromagnetic fields such as radio waves with matter, for example antenna simulation programs like NEC that calculate the radiation pattern of an antenna. Generally being a frequency-domain method, it involves the projection of an integral equation into a system of linear equations by the application of appropriate boundary conditions.
Stratospheric ozone Ultraviolet light Ozone_layer > Ultraviolet light Although the concentration of the ozone in the ozone layer is very small, it is vitally important to life because it absorbs biologically harmful ultraviolet (UV) radiation coming from the Sun. Extremely short or vacuum UV (10–100 nm) is screened out by nitrogen. UV radiation capable of penetrating nitrogen is divided into three categories, based on its wavelength; these are referred to as UV-A (400–315 nm), UV-B (315–280 nm), and UV-C (280–100 nm). UV-C, which is very harmful to all living things, is entirely screened out by a combination of dioxygen (< 200 nm) and ozone (> about 200 nm) by around 35 kilometres (115,000 ft) altitude.
Ionic polymer–metal composites Summary Ionic_polymer-metal_composite Alternatively, if such deformations are physically applied to an IPMC strips they generate an output voltage signal (few millivolts for typical small samples) as sensors and energy harvesters. IPMCs are a type of electroactive polymer. They work very well in a liquid environment as well as in air.
Castellated nut Summary Castellated_nut The bolt has one or two holes drilled through its threaded end. The nut is torqued properly and then, if the slot is not aligned with the hole in the fastener, the nut is rotated forward to the nearest slot.
Historical dynamics Historical simulations Historical_dynamics > Historical simulations Web-based historical simulations, simulations of history, interactive historical simulations, are increasingly popular for entertainment and educational purposes. The field is expanding rapidly and no central index seems to be available. Another example is Several computer games allow players to interact with the game to model societies over time. The Civilization (series) is one example.
Uniform convergence in probability Definitions Uniform_convergence_in_probability > Definitions {\displaystyle Q_{P}(h)=P\{y\in X:h(y)=1\}.} The Uniform Convergence Theorem states, roughly, that if H {\displaystyle H} is "simple" and we draw samples independently (with replacement) from X {\displaystyle X} according to any distribution P {\displaystyle P} , then with high probability, the empirical frequency will be close to its expected value, which is the theoretical probability.Here "simple" means that the Vapnik–Chervonenkis dimension of the class H {\displaystyle H} is small relative to the size of the sample. In other words, a sufficiently simple collection of functions behaves roughly the same on a small random sample as it does on the distribution as a whole. The Uniform Convergence Theorem was first proved by Vapnik and Chervonenkis using the concept of growth function.
Reproduce asexually Spore formation Asexual_reproduction > Types of asexual reproduction > Spore formation These haploid individuals give rise to gametes through mitosis. Meiosis and gamete formation therefore occur in separate generations or "phases" of the life cycle, referred to as alternation of generations. Since sexual reproduction is often more narrowly defined as the fusion of gametes (fertilization), spore formation in plant sporophytes and algae might be considered a form of asexual reproduction (agamogenesis) despite being the result of meiosis and undergoing a reduction in ploidy.
BLOOM (language model) Summary BLOOM_(language_model) The BLOOM project was started by a co-founder of Hugging Face. Six main groups of people were involved, including HuggingFace's BigScience team, the Microsoft DeepSpeed team, the NVIDIA Megatron-LM team, the IDRIS/GENCI team, the PyTorch team, and the volunteers in the BigScience Engineering workgroup.
Shannon's entropy Entropy as a measure of diversity Shannon_Entropy > Aspects > Entropy as a measure of diversity Entropy is one of several ways to measure biodiversity, and is applied in the form of the Shannon index. A diversity index is a quantitative statistical measure of how many different types exist in a dataset, such as species in a community, accounting for ecological richness, evenness, and dominance. Specifically, Shannon entropy is the logarithm of 1D, the true diversity index with parameter equal to 1. The Shannon index is related to the proportional abundances of types.
Acute HIV infection Summary Acute_HIV_infection The stages of HIV infection are acute infection (also known as primary infection), latency, and AIDS. Acute infection lasts for several weeks and may include symptoms such as fever, swollen lymph nodes, inflammation of the throat, rash, muscle pain, malaise, and mouth and esophageal sores. The latency stage involves few or no symptoms and can last anywhere from two weeks to twenty years or more, depending on the individual. AIDS, the final stage of HIV infection, is defined by low CD4+ T cell counts (fewer than 200 per μL), various opportunistic infections, cancers, and other conditions.
Superelectrophilic anion Origin of the concept Superelectrophilic_anion > Origin of the concept However, in direct contrast to this intuitive concept, it was shown in 2017 that the negatively charged gas-phase fragment anion – can bind the noble gases krypton and xenon at room temperature and thus, must be strongly electrophilic. Furthermore, the electrophilicity of this fragment anion could even be increased by exchanging the chlorine atoms (Cl) with cyano groups (CN). The resulting – anion also spontaneously binds the particularly unreactive noble gas argon at room temperature and neon up to a maximum temperature of 50 Kelvin. Thus, it is the most electrophilic anion known to date.Even though anions cannot formally fulfill the concept of superelectrophilic published by Olah (which only refers to cations), these particular anions exhibit reactivity that strongly resembles that of superelectrophilic dications in the gas phase. Thus, the term superelectrophilic anions was used.
Rolling bearing Bearing failure Rolling-element_bearings > Bearing failure As the bearing continues to rotate, the weld is then torn apart, but it may leave race welded to bearing or bearing welded to race.Although there are many other apparent causes of bearing failure, most can be reduced to these three. For example, a bearing which is run dry of lubricant fails not because it is "without lubricant", but because lack of lubrication leads to fatigue and welding, and the resulting wear debris can cause abrasion. Similar events occur in false brinelling damage.
Ground motion Summary Ground_motion Recordings from multiple seismometers can be combined to form a detailed model of the ground motion. This is known as a seismograph, and it can be used to study the spatial and temporal characteristics of the ground motion. Seismographs can also be used to create maps of the ground motion, which can help scientists understand the distribution and intensity of the seismic waves.
Simplified Molecular Input Line Entry Specification Bonds Simplified_Molecular_Input_Line_Entry_Specification > Description > Bonds A bond is represented using one of the symbols . - = # $: / \. Bonds between aliphatic atoms are assumed to be single unless specified otherwise and are implied by adjacency in the SMILES string. Although single bonds may be written as -, this is usually omitted.
Migraine-associated vertigo Signs and symptoms Migraine-associated_vertigo > Signs and symptoms Vertigo is a medically recognized term for the symptom of a vestibular system disturbance. It may include a feeling of rotation or illusory sensations of motion or both. The general term dizziness is used by nonmedical people for those symptoms but often refers to a feeling of light-headedness, giddiness, drowsiness, or faintness, all of which must be differentiated from true vertigo, since the latter symptoms might have other causes. Motion sickness occurs more frequently in migraine patients (30–50% more than in controls).
Internet security Packet filter Internet_security > Countermeasures > Firewalls > Types of firewall > Packet filter A packet filter processes network traffic on a packet-by-packet basis. Its main job is to filter traffic from a remote IP host, so a router is needed to connect the internal network to the Internet. The router is known as a screening router, which screens packets leaving and entering the network.
Constructible numbers Equivalence of algebraic and geometric definitions Constructible_numbers > Equivalence of algebraic and geometric definitions If a {\displaystyle a} and b {\displaystyle b} are the non-zero lengths of geometrically constructed segments then elementary compass and straightedge constructions can be used to obtain constructed segments of lengths a + b {\displaystyle a+b} , | a − b | {\displaystyle |a-b|} , a b {\displaystyle ab} , and a / b {\displaystyle a/b} . The latter two can be done with a construction based on the intercept theorem. A slightly less elementary construction using these tools is based on the geometric mean theorem and will construct a segment of length a {\displaystyle {\sqrt {a}}} from a constructed segment of length a {\displaystyle a} .
Contextual bandit algorithm Summary Multi-armed_bandit_problem In probability theory and machine learning, the multi-armed bandit problem (sometimes called the K- or N-armed bandit problem) is a problem in which a fixed limited set of resources must be allocated between competing (alternative) choices in a way that maximizes their expected gain, when each choice's properties are only partially known at the time of allocation, and may become better understood as time passes or by allocating resources to the choice. This is a classic reinforcement learning problem that exemplifies the exploration–exploitation tradeoff dilemma. The name comes from imagining a gambler at a row of slot machines (sometimes known as "one-armed bandits"), who has to decide which machines to play, how many times to play each machine and in which order to play them, and whether to continue with the current machine or try a different machine. The multi-armed bandit problem also falls into the broad category of stochastic scheduling.
Electrorheological Fluid Composition and theory Electrorheological_Fluid > Composition and theory ER fluids are a type of smart fluid. A simple ER fluid can be made by mixing cornflour in a light vegetable oil or (better) silicone oil. There are two main theories to explain the effect: the interfacial tension or 'water bridge' theory, and the electrostatic theory. The water bridge theory assumes a three phase system, the particles contain the third phase which is another liquid (e.g. water) immiscible with the main phase liquid (e.g. oil).
Directional figure eight Summary Directional_figure_eight The directional figure eight (a.k.a. inline figure-eight loop) is a loop knot. It is a knot that can be made on the bight.
Loop group Summary Loop_group In mathematics, a loop group is a group of loops in a topological group G with multiplication defined pointwise.
Nicholson–Bailey model Variations Nicholson–Bailey_model > Equations > Variations Density dependence can be added to the model, by assuming that the growth rate of the host decreases at high abundances. The equation for the parasitoid is unchanged, and the equation for the host is modified: H t + 1 = H t e r ( 1 − H t / K ) e − a P t P t + 1 = c H t ( 1 − e − a P t ) {\displaystyle {\begin{array}{rcl}H_{t+1}&=&H_{t}e^{r(1-H_{t}/K)}e^{-aP_{t}}\\P_{t+1}&=&cH_{t}\left(1-e^{-aP_{t}}\right)\end{array}}} The host rate of increase k is replaced by r, which becomes negative when the host population density reaches K.
Newton's sine-square law of air resistance Summary Newton's_sine-square_law_of_air_resistance Isaac Newton's sine-squared law of air resistance is a formula that implies the force on a flat plate immersed in a moving fluid is proportional to the square of the sine of the angle of attack. Although Newton did not analyze the force on a flat plate himself, the techniques he used for spheres, cylinders, and conical bodies were later applied to a flat plate to arrive at this formula. In 1687, Newton devoted the second volume of his Principia Mathematica to fluid mechanics.The analysis assumes that the fluid particles are moving at a uniform speed prior to impacting the plate and then follow the surface of the plate after contact. Particles passing above and below the plate are assumed to be unaffected and any particle-to-particle interaction is ignored.
First-order logic with equality Summary First-order_predicate_logic Although the logical consequence relation is only semidecidable, much progress has been made in automated theorem proving in first-order logic. First-order logic also satisfies several metalogical theorems that make it amenable to analysis in proof theory, such as the Löwenheim–Skolem theorem and the compactness theorem. First-order logic is the standard for the formalization of mathematics into axioms, and is studied in the foundations of mathematics.
Adrenergic storm Differential diagnosis Adrenergic_storm > Diagnosis > Differential diagnosis One example would be: overdose of drug(s) influencing multiple targets including serotonin, and adrenergic systems, with concurrent MAOI use). Abnormal echocardiograms, or chest pain are indicative of adrenergic crisis. On the other hand, uncontrollable slow, rhythmic, and/or jerky movements, contractions and tension-often in every part of the body, dangerously high fever, eye rolling, and bruxism are more indicative of serotonin syndrome.
Biologic medical product Gene therapy Biopharmaceutical > Major classes > Gene therapy Viral gene therapy involves artificially manipulating a virus to include a desirable piece of genetic material.
Maxwell Equations Gauss's law Maxwell_equation > Conceptual descriptions > Gauss's law Gauss's law describes the relationship between an electric field and electric charges: an electric field points away from positive charges and towards negative charges, and the net outflow of the electric field through a closed surface is proportional to the enclosed charge, including bound charge due to polarization of material. The coefficient of the proportion is the permittivity of free space.
Flex plate Summary Flex_plate A flexplate (or flex plate) is a metal disk that connects the output from an engine to the input of a torque converter in a car equipped with an automatic transmission. It takes the place of the flywheel found in a conventional manual transmission setup. The name refers to the ability of the disk to flex across its main axis – bending side to side – to take up motion in the torque converter as rotational speeds change. Flexplates are generally much thinner and lighter than flywheels due to the smooth coupling action of the torque converter and the elimination of the clutch surface.
Ionic bonds Properties of ionic bonds Electrovalency > Overview > Properties of ionic bonds This process is called solvation. The presence of these free ions makes aqueous ionic compound solutions good conductors of electricity. The same occurs when the compounds are heated above their melting point, i.e., they are melted. This process is known as ionization.
Laplace domain Examples and applications Laplace_domain > Examples and applications The Laplace transform is used frequently in engineering and physics; the output of a linear time-invariant system can be calculated by convolving its unit impulse response with the input signal. Performing this calculation in Laplace space turns the convolution into a multiplication; the latter being easier to solve because of its algebraic form. For more information, see control theory.
Autocovariance function Normalization Autocovariance_function > Auto-covariance of stochastic processes > Normalization It is common practice in some disciplines (e.g. statistics and time series analysis) to normalize the autocovariance function to get a time-dependent Pearson correlation coefficient. However in other disciplines (e.g. engineering) the normalization is usually dropped and the terms "autocorrelation" and "autocovariance" are used interchangeably. The definition of the normalized auto-correlation of a stochastic process is ρ X X ( t 1 , t 2 ) = K X X ⁡ ( t 1 , t 2 ) σ t 1 σ t 2 = E ⁡ σ t 1 σ t 2 {\displaystyle \rho _{XX}(t_{1},t_{2})={\frac {\operatorname {K} _{XX}(t_{1},t_{2})}{\sigma _{t_{1}}\sigma _{t_{2}}}}={\frac {\operatorname {E} }{\sigma _{t_{1}}\sigma _{t_{2}}}}} .If the function ρ X X {\displaystyle \rho _{XX}} is well-defined, its value must lie in the range {\displaystyle } , with 1 indicating perfect correlation and −1 indicating perfect anti-correlation. For a WSS process, the definition is ρ X X ( τ ) = K X X ⁡ ( τ ) σ 2 = E ⁡ σ 2 {\displaystyle \rho _{XX}(\tau )={\frac {\operatorname {K} _{XX}(\tau )}{\sigma ^{2}}}={\frac {\operatorname {E} }{\sigma ^{2}}}} .where K X X ⁡ ( 0 ) = σ 2 {\displaystyle \operatorname {K} _{XX}(0)=\sigma ^{2}} .
Quantum vacuum zero point energy Cosmic inflation Zero-point_energy > Speculated involvement in other phenomena > Cosmic inflation The mechanism for inflation is unclear, it is similar in effect to dark energy but is a far more energetic and short lived process. As with dark energy the best explanation is some form of vacuum energy arising from quantum fluctuations. It may be that inflation caused baryogenesis, the hypothetical physical processes that produced an asymmetry (imbalance) between baryons and antibaryons produced in the very early universe, but this is far from certain.
Action spectrum Summary Action_spectrum An action spectrum is a graph of the rate of biological effectiveness plotted against wavelength of light. It is related to absorption spectrum in many systems. Mathematically, it describes the inverse quantity of light required to evoke a constant response. It is very rare for an action spectrum to describe the level of biological activity, since biological responses are often nonlinear with intensity.
Viscoelasticity Effect of temperature on viscoelastic behavior Viscoelasticity > Effect of temperature on viscoelastic behavior The temperature in this region for a given polymer is too low to endow molecular motion. Hence the motion of the molecules is frozen in this area. The mechanical property is hard and brittle in this region.
Predictive Model Markup Language PMML Components Predictive_Model_Markup_Language > PMML Components In PMML, outliers can be treated as missing values, as extreme values (based on the definition of high and low values for a particular field), or as is. Missing Value Replacement Policy (attribute missingValueReplacement): if this attribute is specified then a missing value is automatically replaced by the given values. Missing Value Treatment (attribute missingValueTreatment): indicates how the missing value replacement was derived (e.g. as value, mean or median).
Self driving car Summary Semi-autonomous_driving A self-driving car, also known as an autonomous car (AC), driverless car, or robotic car (robo-car), is a car that is capable of traveling without human input. Self-driving cars are responsible for perceiving the environment, monitoring important systems, and control, including navigation. Perception accepts visual and audio data from outside and inside the car and interpret the input to abstractly render the vehicle and its surroundings. The control system then takes actions to move the vehicle, considering the route, road conditions, traffic controls, and obstacles.They have the potential to impact the automotive industry, health, welfare, urban planning, traffic, insurance, labor market, and other domains.
World Water Forum Summary World_Water_Forum The World Water Forum is one of the largest water-related gathering that is jointly organized by the World Water Council and a co-host city that takes place every three years.
Francis Galton Regression toward the mean Francis_Galton > Innovations in statistics and psychological theory > Regression toward the mean Galton was the first to describe and explain the common phenomenon of regression toward the mean, which he first observed in his experiments on the size of the seeds of successive generations of sweet peas. The conditions under which regression toward the mean occurs depend on the way the term is mathematically defined. Galton first observed the phenomenon in the context of simple linear regression of data points. Galton developed the following model: pellets fall through a quincunx or "bean machine" forming a normal distribution centred directly under their entrance point.
Secure multiparty computation History Secure_multi-party_computation > History Special purpose protocols for specific tasks started in the late 1970s. Later, secure computation was formally introduced as secure two-party computation (2PC) in 1982 (for the so-called Millionaires' Problem, a specific problem which is a Boolean predicate), and in generality (for any feasible computation) in 1986 by Andrew Yao. The area is also referred to as Secure Function Evaluation (SFE).
Hemolytic-uremic syndrome Atypical HUS Hemolytic_uremic_syndrome > Cause > Atypical HUS Despite the use of supportive care, an estimated 33–40% of patients will die or have end-stage renal disease (ESRD) with the first clinical manifestation of aHUS, and 65% of patients will die, require dialysis, or have permanent renal damage within the first year after diagnosis despite plasma exchange or plasma infusion (PE/PI) therapy. Patients who survive the presenting signs and symptoms of aHUS endure a chronic thrombotic and inflammatory state, which puts them at lifelong elevated risk of sudden blood clotting, kidney failure, other severe complications and premature death.Historically, treatment options for aHUS were limited to plasma exchange or plasma infusion (PE/PI) therapy, which carries significant risks and has not been proven effective in any controlled trials. People with aHUS and ESRD have also had to undergo lifelong dialysis, which has a 5-year survival rate of 34–38%.
Pitometer log History Pit_log > History All nautical instruments designed to measure the speed of a ship through water are known as logs. This nomenclature dates back to days of sail when sailors tossed a log attached to rope knotted at regular intervals off the stern of a ship. The sailors would count the number of knots that passed through their hands in a given period of time. Today sailors still use the unit of knots to express a ship's speed.
Matrix (protocol) Adoption Matrix_(communication_protocol) > Adoption Employees of the Bundeswehr (Germany's armed forces) communicate with each other, and share classified documents (German VS-NfD), on a private Matrix network, with a customized version of the Matrix Element app. Luxembourg has developed a Matrix-based chat service for government officials, named Luxchat4Gov, planned to be released in the second quartal of 2023. The Swedish Social Insurance Agency (Försäkringskassan) is using Matrix for internal communications.
Left-right symmetry More flavors Left–right_symmetry > Chiral symmetry > More flavors For more "light" quark species, N flavors in general, the corresponding chiral symmetries are U(N)L × U(N)R, decomposing into S U ( N ) L × S U ( N ) R × U ( 1 ) V × U ( 1 ) A , {\displaystyle SU(N)_{\rm {L}}\times SU(N)_{\rm {R}}\times U(1)_{V}\times U(1)_{A}~,} and exhibiting a very analogous chiral symmetry breaking pattern. Most usually, N = 3 is taken, the u, d, and s quarks taken to be light (the Eightfold way (physics)), so then approximately massless for the symmetry to be meaningful to a lowest order, while the other three quarks are sufficiently heavy to barely have a residual chiral symmetry be visible for practical purposes.
Fluidization Summary Fluidization The fluidic behavior allows the particles to be transported like a fluid, channeled through pipes, not requiring mechanical transport (e.g. conveyor belt). A simplified every-day-life example of a gas-solid fluidized bed would be a hot-air popcorn popper.
Injective map Examples Injective_mapping > Examples {\displaystyle g(1)=1=g(-1).} However, if g {\displaystyle g} is redefined so that its domain is the non-negative real numbers [0,+∞), then g {\displaystyle g} is injective. The exponential function exp: R → R {\displaystyle \exp :\mathbb {R} \to \mathbb {R} } defined by exp ⁡ ( x ) = e x {\displaystyle \exp(x)=e^{x}} is injective (but not surjective, as no real value maps to a negative number).
Kepler-20e Summary Kepler-20e Kepler-20e is the first planet smaller than the Earth discovered to orbit a star other than the Sun. A year on Kepler-20e only lasts 6 days, as it is much closer to its host star than the Earth is to the Sun. The temperature at the surface of the planet, around 1400 degrees Fahrenheit, is much too hot to support life, as we know it.
Dot plot (statistics) Summary Dot_plot_(statistics) A dot chart or dot plot is a statistical chart consisting of data points plotted on a fairly simple scale, typically using filled in circles. There are two common, yet very different, versions of the dot chart. The first has been used in hand-drawn (pre-computer era) graphs to depict distributions going back to 1884. The other version is described by William S. Cleveland as an alternative to the bar chart, in which dots are used to depict the quantitative values (e.g. counts) associated with categorical variables.
Segmental arteries of kidney Summary Renal_circulation Each arcuate artery supplies several interlobular arteries that feed into the afferent arterioles that supply the glomeruli. After filtration occurs, the blood moves through a small network of venules that converge into interlobular veins. As with the arteriole distribution, the veins follow the same pattern: the interlobular provide blood to the arcuate veins then back to the interlobar veins, which come to form the renal vein exiting the kidney for transfusion for blood.
Harvest mite Adult Harvest_mite > Life cycle > Adult As deutonymphs and adults, trombiculid mites are independent predators that feed on small arthropods and their eggs, and are also found to eat plant material. They live in soil, and are often found when digging in yards or gardens or in compost bins. Recently (2018), methods based on autofluorescence microscopy were developed to enable identification of trombiculid mites to the species level on the basis of morphological traits without any special preparation.
Generalized eigenvector Differential equations Jordan_chain > Applications > Differential equations In the general case, we try to diagonalize A {\displaystyle A} and reduce the system (5) to a system like (6) as follows. If A {\displaystyle A} is diagonalizable, we have D = M − 1 A M {\displaystyle D=M^{-1}AM} , where M {\displaystyle M} is a modal matrix for A {\displaystyle A} . Substituting A = M D M − 1 {\displaystyle A=MDM^{-1}} , equation (5) takes the form M − 1 x ′ = D ( M − 1 x ) {\displaystyle M^{-1}\mathbf {x} '=D(M^{-1}\mathbf {x} )} , or where The solution of (7) is y 1 = k 1 e λ 1 t {\displaystyle y_{1}=k_{1}e^{\lambda _{1}t}} y 2 = k 2 e λ 2 t {\displaystyle y_{2}=k_{2}e^{\lambda _{2}t}} ⋮ {\displaystyle \vdots } y n = k n e λ n t .
Curve sketching Basic techniques Curve_sketching > Basic techniques Also determine from which side the curve approaches the asymptotes and where the asymptotes intersect the curve. Equate first and second derivatives to 0 to find the stationary points and inflection points respectively. If the equation of the curve cannot be solved explicitly for x or y, finding these derivatives requires implicit differentiation.
Information Processing Language Summary Information_Processing_Language Information Processing Language (IPL) is a programming language created by Allen Newell, Cliff Shaw, and Herbert A. Simon at RAND Corporation and the Carnegie Institute of Technology about 1956. Newell had the job of language specifier-application programmer, Shaw was the system programmer, and Simon had the job of application programmer-user. The code includes features intended to help with programs that perform simple problem solving actions such as lists, dynamic memory allocation, data types, recursion, functions as arguments, generators, and cooperative multitasking. IPL invented the concept of list processing, albeit in an assembly-language style.
The Turing Guide Reviews The_Turing_Guide > Reviews Nuncius. Physics World. Resurrection. SIAM News.The book has also been featured online internationally, including in China.
BitTorrent index Searching BitTorrent > Design > Searching This list can often be sorted with respect to several criteria, relevance (seeders-leechers ratio) being one of the most popular and useful (due to the way the protocol behaves, the download bandwidth achievable is very sensitive to this value). Metasearch engines allow one to search several BitTorrent indices and search engines at once. The Tribler BitTorrent client was among the first to incorporate built-in search capabilities.
Gilbert N. Lewis Thermodynamics Gilbert_N._Lewis > Scientific achievements > Thermodynamics Heat of reaction is not, of course, a measure of the tendency of chemical changes to occur, and Lewis realized that only free energy and entropy could provide an exact chemical thermodynamics. He derived free energy from fugacity; he tried, without success, to obtain an exact expression for the entropy function, which in 1901 had not been defined at low temperatures. Richards too tried and failed, and not until Nernst succeeded in 1907 was it possible to calculate entropies unambiguously.
Cross compile 1987 Cross_compiler > Microsoft C cross compilers > 1987 C programs had long been linked with modules written in assembly language. Most C compilers (even current compilers) offer an assembly language pass (that can be tweaked for efficiency then linked to the rest of the program after assembling). Compilers like Aztec-C converted everything to assembly language as a distinct pass and then assembled the code in a distinct pass, and were noted for their very efficient and small code, but by 1987 the optimizer built into Microsoft C was very good, and only "mission critical" parts of a program were usually considered for rewriting. In fact, C language programming had taken over as the "lowest-level" language, with programming becoming a multi-disciplinary growth industry and projects becoming larger, with programmers writing user interfaces and database interfaces in higher-level languages, and a need had emerged for cross language development that continues to this day.
Complex geometry Idea Complex_geometry > Idea In some sense, the novelty of complex geometry may be traced back to this fundamental observation. It is true that every complex manifold is in particular a real smooth manifold.
Square-inch analysis Obtaining Measurements Square-inch_analysis > Applications > Obtaining Measurements A more conservative square-inch analysis proportionately subdivides the total of all "white space" and adds an apportionment to each item's offer area so that the cost of every square inch of space is accounted for. With the emergence of software-assisted page planning, graphic design and page layout techniques, obtaining square-inch measurements has become at least partially automated. Software systems which store dimensional data related to sales offers as shown on page layouts should be capable of delivering the necessary area measurements for each item offered on each page in tabular form.
Ribozyme Discovery Ribozyme > Discovery As much as they tried, Cech and his colleagues could not identify any protein associated with the splicing reaction. After much work, Cech proposed that the intron sequence portion of the RNA could break and reform phosphodiester bonds. At about the same time, Sidney Altman, a professor at Yale University, was studying the way tRNA molecules are processed in the cell when he and his colleagues isolated an enzyme called RNase-P, which is responsible for conversion of a precursor tRNA into the active tRNA.
Dandy–Walker malformation Criteria and classification Dandy–Walker_syndrome > Diagnosis > Criteria and classification The posterior fossa (the space behind the cerebellum) is enlarged, and its cerebrospinal fluid flow is continuous with that of the fourth ventricle. The rest of the cerebellar vermis is hypoplastic and is pushed upwards and rotated forwards due to the enlarged posterior fossa. The cerebellar hemispheres are pushed forwards and to the side by the enlarged posterior fossa.
Hyperexponential distribution Summary Hyper-exponential_distribution In probability theory, a hyperexponential distribution is a continuous probability distribution whose probability density function of the random variable X is given by f X ( x ) = ∑ i = 1 n f Y i ( x ) p i , {\displaystyle f_{X}(x)=\sum _{i=1}^{n}f_{Y_{i}}(x)\;p_{i},} where each Yi is an exponentially distributed random variable with rate parameter λi, and pi is the probability that X will take on the form of the exponential distribution with rate λi. It is named the hyperexponential distribution since its coefficient of variation is greater than that of the exponential distribution, whose coefficient of variation is 1, and the hypoexponential distribution, which has a coefficient of variation smaller than one. While the exponential distribution is the continuous analogue of the geometric distribution, the hyperexponential distribution is not analogous to the hypergeometric distribution. The hyperexponential distribution is an example of a mixture density. An example of a hyperexponential random variable can be seen in the context of telephony, where, if someone has a modem and a phone, their phone line usage could be modeled as a hyperexponential distribution where there is probability p of them talking on the phone with rate λ1 and probability q of them using their internet connection with rate λ2.
SQUID magnetometers Survey magnetometers Fluxgate_magnetometer > Survey magnetometers Survey magnetometers can be divided into two basic types: Scalar magnetometers measure the total strength of the magnetic field to which they are subjected, but not its direction Vector magnetometers have the capability to measure the component of the magnetic field in a particular direction, relative to the spatial orientation of the device.A vector is a mathematical entity with both magnitude and direction. The Earth's magnetic field at a given point is a vector. A magnetic compass is designed to give a horizontal bearing direction, whereas a vector magnetometer measures both the magnitude and direction of the total magnetic field. Three orthogonal sensors are required to measure the components of the magnetic field in all three dimensions.
Evolution of the brain Early history of brain development Evolution_of_the_brain > Early history of brain development In reptiles and fish, this area is called the pallium, and is smaller and simpler relative to body mass than what is found in mammals. According to research, the cerebrum first developed about 200 million years ago. It's responsible for higher cognitive functions - for example, language, thinking, and related forms of information processing.
Nikon FA Features Nikon_FA > Features However, AMP was still demonstrably superior to the centerweighted type of light metering then in common use. AMP would give a good exposure 90-95% of the time versus 85-90% for centerweighting. Note that AMP was automatically disabled in the FA's manual exposure mode and could be turned off in the autoexposure modes.
Electrical engineering Tools and work Electrical_engineering > Tools and work Today most engineering work involves the use of computers and it is commonplace to use computer-aided design programs when designing electrical systems. Nevertheless, the ability to sketch ideas is still invaluable for quickly communicating with others. Although most electrical engineers will understand basic circuit theory (that is the interactions of elements such as resistors, capacitors, diodes, transistors, and inductors in a circuit), the theories employed by engineers generally depend upon the work they do.
Symmetric algebra Relationship with symmetric tensors Symmetric_algebra > Relationship with symmetric tensors More precisely, given σ ∈ S n , {\displaystyle \sigma \in {\mathcal {S}}_{n},} the transformation v 1 ⊗ ⋯ ⊗ v n ↦ v σ ( 1 ) ⊗ ⋯ ⊗ v σ ( n ) {\displaystyle v_{1}\otimes \cdots \otimes v_{n}\mapsto v_{\sigma (1)}\otimes \cdots \otimes v_{\sigma (n)}} defines a linear endomorphism of Tn(V). A symmetric tensor is a tensor that is invariant under all these endomorphisms. The symmetric tensors of degree n form a vector subspace (or module) Symn(V) ⊂ Tn(V).
Linear belief function Applications Linear_belief_function > Applications If the auditor knows nothing about the beginning balance of accounts receivable, we can represent his or her ignorance by a vacuous LBF. Finally, if historical data suggests that, given cash receipts C, the sales S is on the average 8C + 4 and has a standard deviation 4 thousand dollars, we can represent the knowledge as a linear regression model S ~ N(4 + 8C, 16). == References ==
Small nucleolar RNA TBR2 Summary Small_nucleolar_RNA_TBR2 Small nucleolar RNA TBR2 is a non-coding RNA (ncRNA) molecule identified in Trypanosoma brucei which functions in the modification of other small nuclear RNAs (snRNAs). This type of modifying RNA is usually located in the nucleolus of the eukaryotic cell which is a major site of snRNA biogenesis. It is known as a small nucleolar RNA (snoRNA) and also often referred to as a guide RNA. snoRNA TBR2 belongs to the C/D box class of snoRNAs which contain the conserved sequence motifs known as the C box (UGAUGA) and the D box (CUGA).
Algorithmic topology Algorithmic 3-manifold theory Computational_topology > Major algorithms by subject area > Algorithmic 3-manifold theory Moreover, it is implemented in the software package Regina. Saul Schleimer went on to show the problem lies in the complexity class NP. Furthermore, Raphael Zentner showed that the problem lies in the complexity class coNP, provided that the generalized Riemann hypothesis holds.
Propellant Vehicle propellants Gun_propellant > Vehicle propellants Electothermal engines use the electromagnetic force to heat low molecular weight gases (e.g. hydrogen, helium, ammonia) into a plasma and expel the plasma as propellant. In the case of a resistojet rocket engine, the compressed propellant is simply heated using resistive heating as it is expelled to create more thrust. In chemical rockets and aircraft, fuels are used to produce an energetic gas that can be directed through a nozzle, thereby producing thrust.
Protein Crystallography Intuitive understanding by Bragg's law X-ray_crystal_structure > Diffraction theory > Intuitive understanding by Bragg's law An intuitive understanding of X-ray diffraction can be obtained from the Bragg model of diffraction. In this model, a given reflection is associated with a set of evenly spaced sheets running through the crystal, usually passing through the centers of the atoms of the crystal lattice. The orientation of a particular set of sheets is identified by its three Miller indices (h, k, l), and let their spacing be noted by d. William Lawrence Bragg proposed a model in which the incoming X-rays are scattered specularly (mirror-like) from each plane; from that assumption, X-rays scattered from adjacent planes will combine constructively (constructive interference) when the angle θ between the plane and the X-ray results in a path-length difference that is an integer multiple n of the X-ray wavelength λ. 2 d sin ⁡ θ = n λ .
Feynman path integrals Ward–Takahashi identities Feynman_path_integrals > Localization > Ward–Takahashi identities And this does not hold in general. See anomaly (physics) for more details. Then, ∫ D φ Q = 0 , {\displaystyle \int {\mathcal {D}}\varphi \,Q\left=0,} which implies ⟨ Q ⟩ + i ⟨ F ∫ ∂ V f μ d s μ ⟩ = 0 {\displaystyle \langle Q\rangle +i\left\langle F\int _{\partial V}f^{\mu }\,ds_{\mu }\right\rangle =0} where the integral is over the boundary.
Heavy element Criticism Heavy_metal_(chemical_element) > Origins and use of the term > Criticism In 2002, Scottish toxicologist John Duffus reviewed the definitions used over the previous 60 years and concluded they were so diverse as to effectively render the term meaningless. Along with this finding, the heavy metal status of some metals is occasionally challenged on the grounds that they are too light, or are involved in biological processes, or rarely constitute environmental hazards. Examples include scandium (too light); vanadium to zinc (biological processes); and rhodium, indium, and osmium (too rare).
Magnetic nanoparticle Medical diagnostics and treatments Magnetic_nanoparticles > Potential applications > Medical diagnostics and treatments Another potential treatment of cancer includes attaching magnetic nanoparticles to free-floating cancer cells, allowing them to be captured and carried out of the body. The treatment has been tested in the laboratory on mice and will be looked at in survival studies.Magnetic nanoparticles can be used for the detection of cancer. Blood can be inserted onto a microfluidic chip with magnetic nanoparticles in it.