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Accessible housing United States Accessible_housing > United States In the United States, the 1988 Amendments to the Fair Housing Act added people with disabilities, as well as familial status, to the classes already protected by law from discrimination (race, color, gender, religion, creed, and country of origin). Among the protection for people with disabilities in the 1988 Amendments are seven construction requirements for all multifamily buildings of more than four units first occupied after March 13, 1991. These seven requirements are as follows: An accessible building entrance on an accessible route, Accessible common and public use areas, Doors usable by a person in a wheelchair, Accessible route into and through the dwelling unit, Light switches, electrical outlets, thermostats and other environmental controls in accessible locations, Reinforced walls in bathrooms for later installation of grab bars, and Usable kitchens and bathrooms.Access is typically defined within the limits of what a person sitting in a wheelchair is able to reach with arm movement only, with minimal shifting of the legs and torso. Lighting and thermostat controls should not be above and power outlets should not be below the reach of a person in a wheelchair.
Interferometric synthetic-aperture radar Persistent scatterer InSAR Interferometric_synthetic-aperture_radar > Technique > Persistent scatterer InSAR Some research centres and companies, were inspired to develop variations of their own algorithms which would also overcome InSAR's limitations. In scientific literature, these techniques are collectively referred to as persistent scatterer interferometry or PSI techniques. The term persistent scatterer interferometry (PSI) was proposed by European Space Agency (ESA) to define the second generation of radar interferometry techniques.
History of tuberculosis Books History_of_tuberculosis > References > Books Debus, Allen G. (2001). Chemistry and Medical Debate: Van Helmont to Boerhaave.
Group Theory Applications of group theory Abstract_group > Applications of group theory Applications of group theory abound. Almost all structures in abstract algebra are special cases of groups. Rings, for example, can be viewed as abelian groups (corresponding to addition) together with a second operation (corresponding to multiplication). Therefore, group theoretic arguments underlie large parts of the theory of those entities.
Phosphide iodide Summary Phosphide_iodide Related compounds include the phosphide chlorides, arsenide iodides antimonide iodides and phosphide bromides. Phosphorus can form clusters or chains in these compounds, so that some are 1-dimensional or fibrous. Phosphide iodides are often metallic, black or dark red in colour.
Megakaryocyte Essential thrombocythemia Megakaryocyte > Clinical significance > Essential thrombocythemia Approximately half ET cases are due to a mutation in the JAK2 protein, a member of the JAK-STAT signaling pathway. This mutation induces an unregulated proliferative signal from the thrombopoietin (TPO) receptor in the absence of TPO causing clonal expansion of bone marrow cells, especially megakaryocytes. There is a low risk of transformation to leukemia with this disorder. The primary treatment consists of anagrelide or hydroxyurea to lower platelet levels.
Menopause Mechanism Menopause > Mechanism The menopausal transition, and postmenopause itself, is a natural change, not usually a disease state or a disorder. The main cause of this transition is the natural depletion and aging of the finite amount of oocytes (ovarian reserve). This process is sometimes accelerated by other conditions and is known to occur earlier after a wide range of gynecologic procedures such as hysterectomy (with and without ovariectomy), endometrial ablation and uterine artery embolisation. The depletion of the ovarian reserve causes an increase in circulating follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels because there are fewer oocytes and follicles responding to these hormones and producing estrogen.
Metabolic pathway Catabolic pathway (catabolism) Biochemical_pathways > Major metabolic pathways > Catabolic pathway (catabolism) Coupled with an endergonic reaction of anabolism, the cell can synthesize new macromolecules using the original precursors of the anabolic pathway. An example of a coupled reaction is the phosphorylation of fructose-6-phosphate to form the intermediate fructose-1,6-bisphosphate by the enzyme phosphofructokinase accompanied by the hydrolysis of ATP in the pathway of glycolysis. The resulting chemical reaction within the metabolic pathway is highly thermodynamically favorable and, as a result, irreversible in the cell. Fructose − 6 − Phosphate + ATP ⟶ Fructose − 1 , 6 − Bisphosphate + ADP {\displaystyle {\ce {Fructose-6-Phosphate + ATP -> Fructose-1,6-Bisphosphate + ADP}}}
Muffin-tin approximation Summary Muffin_tin_approximation One application is found in the variational theory developed by Jan Korringa (1947) and by Walter Kohn and N. Rostoker (1954) referred to as the KKR method. This method has been adapted to treat random materials as well, where it is called the KKR coherent potential approximation.In its simplest form, non-overlapping spheres are centered on the atomic positions. Within these regions, the screened potential experienced by an electron is approximated to be spherically symmetric about the given nucleus.
Top level domain Pseudo-domains Top_level_domain > Pseudo-domains One notable exception is the 2007 emergence of SWIFTNet Mail, which uses the swift pseudo-domain.The anonymity network Tor formerly used the top-level pseudo-domain .onion for onion services, which can only be reached with a Tor client because it uses the Tor onion routing protocol to reach the hidden service to protect the anonymity of users. However, the pseudo-domain became officially reserved in October 2015. i2p provides a similar hidden pseudo-domain, .i2p. And Namecoin uses the .bit pseudo-domain. BT hubs use the top-level pseudo-domain .home for local DNS resolution of routers, modems, and gateways.
Regenerative Medicine Non-technical further reading Regenerative_Medicine > Further reading > Non-technical further reading Regenerative Medicine, gives more details about Regenerative Stem Cells. Cogle CR; Guthrie SM; Sanders RC; Allen WL; Scott EW; Petersen BE (August 2003). "An overview of stem cell research and regulatory issues". Mayo Clinic Proceedings.
Multiplicative number theory Methods Multiplicative_number_theory > Methods The methods belong primarily to analytic number theory, but elementary methods, especially sieve methods, are also very important. The large sieve and exponential sums are usually considered part of multiplicative number theory. The distribution of prime numbers is closely tied to the behavior of the Riemann zeta function and the Riemann hypothesis, and these subjects are studied both from a number theory viewpoint and a complex analysis viewpoint.
Solid aluminum capacitor (SAL) Construction SAL_electrolytic_capacitor > Construction Basic anode material of solid aluminum capacitors exists of highly purified aluminum with a purity of at least 99.99%. In an electrochemical process the anode material is etched (roughened) to increase the effective electrode surface. After that the roughened aluminum becomes oxidized or formed by an anodic oxidizing process. Thereby an electrical insulating oxide layer Al2O3 is formed on the aluminum surface by applying an electric current in correct polarity in an electrolytic bath.
Semigroup algebra Augmentation Semigroup_ring > Augmentation The augmentation is the ring homomorphism η: R → R defined by η ( ∑ g ∈ G r g g ) = ∑ g ∈ G r g . {\displaystyle \eta \left(\sum _{g\in G}r_{g}g\right)=\sum _{g\in G}r_{g}.} The kernel of η is called the augmentation ideal. It is a free R-module with basis consisting of 1 – g for all g in G not equal to 1.
Recursive step Formal definitions Recursive_structure > Formal definitions By this base case and recursive rule, one can generate the set of all natural numbers. Other recursively defined mathematical objects include factorials, functions (e.g., recurrence relations), sets (e.g., Cantor ternary set), and fractals. There are various more tongue-in-cheek definitions of recursion; see recursive humor.
Forensic identification DNA identification Forensic_identification > Human identification > Primary methods > DNA identification It is also used to link suspects or victims to each other or to crime scenes. When a sample is located at a crime scene, it must be collected, processed, and transported, along with a chain of custody, to the laboratory for analysis, so that if a DNA profile is generated it can be accepted in court. Proper evidence collection and preservation is crucial to ensure evidence is not being contaminated.
Critical line theorem Consequences of the generalized Riemann hypothesis Riemann_Hypothesis > Consequences > Consequences of the generalized Riemann hypothesis Several applications use the generalized Riemann hypothesis for Dirichlet L-series or zeta functions of number fields rather than just the Riemann hypothesis. Many basic properties of the Riemann zeta function can easily be generalized to all Dirichlet L-series, so it is plausible that a method that proves the Riemann hypothesis for the Riemann zeta function would also work for the generalized Riemann hypothesis for Dirichlet L-functions. Several results first proved using the generalized Riemann hypothesis were later given unconditional proofs without using it, though these were usually much harder. Many of the consequences on the following list are taken from Conrad (2010).
Blood in stool Specific treatment Blood_in_stool > Treatment > Specific treatment Diagnostic measures can be used as interventions to help stop bleeding in some cases. Bleeding that occurs due to a neoplasm (cancer growth) can be treated using colonoscopy and clipping, surgical intervention, or other measures, depending on the form and stage of cancer. Similarly, stomach cancer is treated depending on the staging, although typically requires surgical and medical therapy.The treatment for motility issues, namely constipation, is typically to improve the movement of waste through the GI tract. This is done by using stool softeners (which work by pulling water into the stool while in the colon), addition of fiber to the diet, and use of osmotic laxatives (which help fluid movement through the colon, improving overall motility).
Histidine kinase Role in bacteria infections Histidine_kinase > Role in bacteria infections Similar to fungus, Two component systems can also be found in several persistent bacteria infections. For example, Staphylococcus aureus was reported to use SrrAB TCSs consisting of a sensor HKs (SrrB), which would transfer phosphate group to an effector response regulator (SrrA), leading to the modification of SrrA activity including gene regulation. This TCSs has been used by S. aureus in order to sense changes of environmental condition and transmit the signal to an appropriate responding system, for example, ica genes is induced by SrrAB to mediate cell assembly and biofilm formation to survive under anaerobic condition.
Available energy A historical and cultural tangent Exergy > Mathematical description > A historical and cultural tangent In 1848, William Thomson, 1st Baron Kelvin, asked (and immediately answered) the question Is there any principle on which an absolute thermometric scale can be founded? It appears to me that Carnot's theory of the motive power of heat enables us to give an affirmative answer.With the benefit of the hindsight contained in equation (3), we are able to understand the historical impact of Kelvin's idea on physics. Kelvin suggested that the best temperature scale would describe a constant ability for a unit of temperature in the surroundings to alter the available work from Carnot's engine. From equation (3): Rudolf Clausius recognized the presence of a proportionality constant in Kelvin's analysis and gave it the name entropy in 1865 from the Greek for "transformation" because it describes the quantity of energy lost during the transformation from heat to work.
Infrared eye Infrared Financial Messaging Infrared_Data_Association > Specifications > Infrared Financial Messaging Infrared Financial Messaging (IrFM) is a wireless payment standard developed by the Infrared Data Association. It was thought to be logical because of the excellent privacy of IrDA, which does not pass through walls.
Markov Decision Processes Linear programming formulation Markov_Decision_Processes > Continuous-time Markov decision process > Linear programming formulation If the state space and action space are finite, we could use linear programming to find the optimal policy, which was one of the earliest approaches applied. Here we only consider the ergodic model, which means our continuous-time MDP becomes an ergodic continuous-time Markov chain under a stationary policy. Under this assumption, although the decision maker can make a decision at any time at the current state, they could not benefit more by taking more than one action.
Maxwell's theory Auxiliary fields, polarization and magnetization Maxwell's_field_equations > Macroscopic formulation > Auxiliary fields, polarization and magnetization The definitions of the auxiliary fields are: where P is the polarization field and M is the magnetization field, which are defined in terms of microscopic bound charges and bound currents respectively. The macroscopic bound charge density ρb and bound current density Jb in terms of polarization P and magnetization M are then defined as If we define the total, bound, and free charge and current density by and use the defining relations above to eliminate D, and H, the "macroscopic" Maxwell's equations reproduce the "microscopic" equations.
Long double Implementations Long_double > long double in C > Implementations As of gcc 4.3, a quadruple precision is also supported on x86, but as the nonstandard type __float128 rather than long double.Although the x86 architecture, and specifically the x87 floating-point instructions on x86, supports 80-bit extended-precision operations, it is possible to configure the processor to automatically round operations to double (or even single) precision. Conversely, in extended-precision mode, extended precision may be used for intermediate compiler-generated calculations even when the final results are stored at a lower precision (i.e. FLT_EVAL_METHOD == 2). With gcc on Linux, 80-bit extended precision is the default; on several BSD operating systems (FreeBSD and OpenBSD), double-precision mode is the default, and long double operations are effectively reduced to double precision.
Stress (biology) Biological need for equilibrium Stress_(biology) > Biological need for equilibrium The brain cannot live in an harsh family environment, it needs some sort of stability between another brain. People who have reported being raised in harsh environments such as verbal and physical aggression have showed a more immune dysfunction and more metabolic dysfunction. Indeed, in 1995 Toates already defined stress as a "chronic state that arises only when defense mechanisms are either being chronically stretched or are actually failing," while according to Ursin (1988) stress results from an inconsistency between expected events ("set value") and perceived events ("actual value") that cannot be resolved satisfactorily, which also puts stress into the broader context of cognitive-consistency theory.
Evolutionary graph theory Summary Evolutionary_graph_theory We may consider the mutant population on a graph as a random walk between absorbing barriers representing mutant extinction and mutant fixation. For highly symmetric graphs, we can then use martingales to find the fixation probability as illustrated by Monk (2018). Also evolutionary games can be studied on graphs where again an edge between i and j means that these two individuals will play a game against each other. Closely related stochastic processes include the voter model, which was introduced by Clifford and Sudbury (1973) and independently by Holley and Liggett (1975), and which has been studied extensively.
Liver metabolism Microscopic anatomy Fetal_liver > Structure > Microscopic anatomy The portal triad consists of the hepatic artery, the portal vein, and the common bile duct. The triad may be seen on a liver ultrasound, as a Mickey Mouse sign with the portal vein as the head, and the hepatic artery, and the common bile duct as the ears.Histology, the study of microscopic anatomy, shows two major types of liver cell: parenchymal cells and nonparenchymal cells. About 70–85% of the liver volume is occupied by parenchymal hepatocytes.
Methocarbamol Metabolism Methocarbamol > Pharmacology > Metabolism Methocarbamol is the carbamate derivative of guaifenesin, but does not produce guaifenesin as a metabolite, because the carbamate bond is not hydrolyzed metabolically; its metabolism is by Phase I ring hydroxylation and O-demethylation, followed by Phase II conjugation. All the major metabolites are unhydrolyzed carbamates. Small amounts of unchanged methocarbamol are also excreted in the urine.
Normal matrix Normal matrix analogy Normal_matrix > Normal matrix analogy It is occasionally useful (but sometimes misleading) to think of the relationships of special kinds of normal matrices as analogous to the relationships of the corresponding type of complex numbers of which their eigenvalues are composed. This is because any function of a non-defective matrix acts directly on each of its eigenvalues, and the conjugate transpose of its spectral decomposition V D V ∗ {\displaystyle VDV^{}} is V D ∗ V ∗ {\displaystyle VD^{}V^{*}} , where D {\displaystyle D} is the diagonal matrix of eigenvalues. Likewise, if two normal matrices commute and are therefore simultaneously diagonalizable, any operation between these matrices also acts on each corresponding pair of eigenvalues. The conjugate transpose is analogous to the complex conjugate.
Quantum field effect transistor Structure and device operation Quantum_field_effect_transistor > Structure and device operation Quantum wires are essentially channels in a 1D system, providing a tighter carrier confinement and a predictable current flow.Traditional MOSFETs, constructed with a silicon dioxide layer on top of a silicon substrate, operate by creating a biased p-n junction, which can be forward or reverse biased in the presence of a positive or negative applied voltage, respectively. In effect, applying a voltage reduces the height of the potential barrier between the p and n regions and allows for charge to flow in the form of positively charged "holes" and negatively charged electrons. Single-junction QFET's use quantum tunneling to increase speed by eliminating the electronic conduction area, which slows down carriers by up to 3000 times.
Abstract data type Example: abstract stack (functional) Abstract_data_type > Defining an abstract data type > Functional-style definition > Example: abstract stack (functional) For example, a complete functional-style definition of an abstract stack could use the three operations: push: takes a stack state and an arbitrary value, returns a stack state; top: takes a stack state, returns a value; pop: takes a stack state, returns a stack state.In a functional-style definition there is no need for a create operation. Indeed, there is no notion of "stack instance". The stack states can be thought of as being potential states of a single stack structure, and two-stack states that contain the same values in the same order are considered to be identical states.
Momentum curtain Summary Momentum_curtain Cockerell used the idea of pumped air under a hull (this then becoming a plenum, i.e. the opposite of a vacuum) and improved upon it further. Simply pumping air between a hull and the ground wasted a lot of energy in terms of leakage of air around the edges of the hull. Cockerell discovered that by means of generating a wall (curtain) of high-speed downward-directed air around the edges of a hull, that less air leaked out from the sides (due to the momentum of the high-speed air molecules), and thus a greater pressure could be attained beneath the hull.
K-theory of a category Summary K-theory_of_a_category In algebraic K-theory, the K-theory of a category C (usually equipped with some kind of additional data) is a sequence of abelian groups Ki(C) associated to it. If C is an abelian category, there is no need for extra data, but in general it only makes sense to speak of K-theory after specifying on C a structure of an exact category, or of a Waldhausen category, or of a dg-category, or possibly some other variants. Thus, there are several constructions of those groups, corresponding to various kinds of structures put on C. Traditionally, the K-theory of C is defined to be the result of a suitable construction, but in some contexts there are more conceptual definitions.
Neurokinin A Immune system Neurokinin_A > Mechanism of action > Immune system The immune system is a highly integrated system which receives input from many sources, such as sites of injury, nociceptors and white blood cells. Chemical signals therefore are an important component of paracrine, autocrine and endocrine signaling. Neurokinin A was shown to be a potent chemo attractor for T-cells increasing the migration into infected tissues. This migration is necessary for the pathogen seeking activity of T-cells.
Closed- loop Main control strategies Closed_loop_control > Main control strategies The first can more explicitly take into account constraints on the signals in the system, which is an important feature in many industrial processes. However, the "optimal control" structure in MPC is only a means to achieve such a result, as it does not optimize a true performance index of the closed-loop control system. Together with PID controllers, MPC systems are the most widely used control technique in process control.
Predator-prey dynamics Biological interpretation and model assumptions Predator-prey_dynamics > Biological interpretation and model assumptions The term δxy represents the growth of the predator population. (Note the similarity to the predation rate; however, a different constant is used, as the rate at which the predator population grows is not necessarily equal to the rate at which it consumes the prey). The term γy represents the loss rate of the predators due to either natural death or emigration; it leads to an exponential decay in the absence of prey.
Barn-pole paradox Resolution Barn-pole_paradox > Resolution The door closes, and then opens again to let the front of the ladder pass through. At a later time, the back of the ladder passes through the entrance door, which closes and then opens. We see that, as simultaneity is relative, the two doors did not need to be shut at the same time, and the ladder did not need to fit inside the garage.
Friendly artificial intelligence Criticism Friendly_AI > Criticism In an article in AI & Society, Boyles and Joaquin maintain that such AIs would not be that friendly considering the following: the infinite amount of antecedent counterfactual conditions that would have to be programmed into a machine, the difficulty of cashing out the set of moral values—that is, those that are more ideal than the ones human beings possess at present, and the apparent disconnect between counterfactual antecedents and ideal value consequent.Some philosophers claim that any truly "rational" agent, whether artificial or human, will naturally be benevolent; in this view, deliberate safeguards designed to produce a friendly AI could be unnecessary or even harmful. Other critics question whether it is possible for an artificial intelligence to be friendly. Adam Keiper and Ari N. Schulman, editors of the technology journal The New Atlantis, say that it will be impossible to ever guarantee "friendly" behavior in AIs because problems of ethical complexity will not yield to software advances or increases in computing power. They write that the criteria upon which friendly AI theories are based work "only when one has not only great powers of prediction about the likelihood of myriad possible outcomes, but certainty and consensus on how one values the different outcomes.
Systemic corticosteroids Systemic forms Nasal_steroid > Classification of corticosteroids > By route of administration > Systemic forms Available in injectables for intravenous and parenteral routes.
Rendering algorithm Neural rendering Rendering_engine > Techniques > Neural rendering Neural rendering is a rendering method using artificial neural networks. Neural rendering includes image-based rendering methods that are used to reconstruct 3D models from 2-dimensional images.One of these methods are photogrammetry, which is a method in which a collection of images from multiple angles of an object are turned into a 3D model. There have also been recent developments in generating and rendering 3D models from text and coarse paintings by notably Nvidia, Google and various other companies.
Fluid flywheel Summary Fluid_coupling A fluid coupling or hydraulic coupling is a hydrodynamic or 'hydrokinetic' device used to transmit rotating mechanical power. It has been used in automobile transmissions as an alternative to a mechanical clutch. It also has widespread application in marine and industrial machine drives, where variable speed operation and controlled start-up without shock loading of the power transmission system is essential. Hydrokinetic drives, such as this, should be distinguished from hydrostatic drives, such as hydraulic pump and motor combinations.
Promoter (genetics) Summary Promoter_(genetics) In genetics, a promoter is a sequence of DNA to which proteins bind to initiate transcription of a single RNA transcript from the DNA downstream of the promoter. The RNA transcript may encode a protein (mRNA), or can have a function in and of itself, such as tRNA or rRNA. Promoters are located near the transcription start sites of genes, upstream on the DNA (towards the 5' region of the sense strand). Promoters can be about 100–1000 base pairs long, the sequence of which is highly dependent on the gene and product of transcription, type or class of RNA polymerase recruited to the site, and species of organism.Promoters control gene expression in bacteria and eukaryotes.
Moore neighborhood Importance Moore_neighborhood > Importance The concept can be extended to higher dimensions, for example forming a 26-cell cubic neighborhood for a cellular automaton in three dimensions, as used by 3D Life. In dimension d, where 0 ≤ d , d ∈ Z {\displaystyle 0\leq d,d\in \mathbb {Z} } , the size of the neighborhood is 3d − 1. In two dimensions, the number of cells in an extended Moore neighbourhood of range r is (2r + 1)2.
Chemotherapy-induced peripheral neuropathy Diagnosis Chemotherapy-induced_peripheral_neuropathy > Diagnosis Second, the drug dose the patient received, and if its amount is commensurate with developing CIPN, must be considered. The immunomodulatory drug bortezomib, for example, is more likely to cause neurotoxicity in a cumulative dose of 20 grams. Finally, the characteristics and the duration of a patient's symptoms should be analyzed.
Autonomous Agency Theory Summary Autonomous_Agency_Theory Autonomous agency theory (AAT) is a viable system theory (VST) which models autonomous social complex adaptive systems. It can be used to model the relationship between an agency and its environment(s), and these may include other interactive agencies. The nature of that interaction is determined by both the agency's external and internal attributes and constraints. Internal attributes may include immanent dynamic "self" processes that drive agency change.
Just-in-time compiler Performance Just-in-time_compilation > Performance Additionally, since a program spends most time executing a minority of its code, the reduced compilation time is significant. Finally, during the initial code interpretation, execution statistics can be collected before compilation, which helps to perform better optimization.The correct tradeoff can vary due to circumstances. For example, Sun's Java Virtual Machine has two major modes—client and server.
Arlene Fiore Career and research Arlene_Fiore > Career and research As an undergraduate at Harvard University, Fiore worked on ozone smog for her honors thesis. As a graduate student at Harvard, Fiore worked with the Harvard Atmospheric Chemistry Modeling Group. Before becoming a professor, Fiore continued her research at the Atmospheric and Ocean Sciences Program at Princeton University, the Geophysical Fluid Dynamics Laboratory, and the National Center for Atmospheric Research. In 2011, Fiore started as a professor in the Department of Earth and Environmental Sciences and Lamont–Doherty Earth Observatory of Columbia University in Palisades, NY.
Metal-Insulator-Semiconductor Field-Effect Transistor Circuit symbols MOS_capacitor > Circuit symbols For enhancement-mode and depletion-mode MOSFET symbols (in columns two and five), the source terminal is the one connected to the triangle. Additionally, in this diagram, the gate is shown as an "L" shape, whose input leg is closer to S than D, also indicating which is which. However, these symbols are often drawn with a "T" shaped gate (as elsewhere on this page), so it is the triangle which must be relied upon to indicate the source terminal.
H2S Precursor to metal sulfides H₂S > Uses > Precursor to metal sulfides As indicated above, many metal ions react with hydrogen sulfide to give the corresponding metal sulfides. This conversion is widely exploited. For example, gases or waters contaminated by hydrogen sulfide can be cleaned with metals, by forming metal sulfides. In the purification of metal ores by flotation, mineral powders are often treated with hydrogen sulfide to enhance the separation. Metal parts are sometimes passivated with hydrogen sulfide. Catalysts used in hydrodesulfurization are routinely activated with hydrogen sulfide, and the behavior of metallic catalysts used in other parts of a refinery is also modified using hydrogen sulfide.
Composite Material Other fabrication methods Layup_mold > Methods of fabrication > Other fabrication methods Other types of fabrication include casting, centrifugal casting, braiding (onto a former), continuous casting, filament winding, press moulding, transfer moulding, pultrusion moulding, and slip forming. There are also forming capabilities including CNC filament winding, vacuum infusion, wet lay-up, compression moulding, and thermoplastic moulding, to name a few. The practice of curing ovens and paint booths is also required for some projects.
Two-square cipher Algorithm Two-square_cipher > Algorithm For vertical two-square, a plaintext digraph that ends up with both characters in the same column gives the same digraph in the ciphertext. For horizontal two-square, a plaintext digraph with both characters in the same row gives (by convention) that digraph with the characters reversed in the ciphertext. In cryptography this is referred to as a transparency.
User-mode Linux Comparison with other technologies User-mode_Linux > Comparison with other technologies User-mode Linux is generally considered to have lower performance than some competing technologies, such as Xen and OpenVZ. Future work in adding support for x86 virtualization to UML may reduce this disadvantage. Often cited as a strength of Xen (a competing technology) is support for thread-local storage (TLS). This is now also supported in the latest UML kernels.
Paleontology History Paleontology > History Within the next few years the role and operation of DNA in genetic inheritance were discovered, leading to what is now known as the "Central Dogma" of molecular biology. In the 1960s molecular phylogenetics, the investigation of evolutionary "family trees" by techniques derived from biochemistry, began to make an impact, particularly when it was proposed that the human lineage had diverged from apes much more recently than was generally thought at the time. Although this early study compared proteins from apes and humans, most molecular phylogenetics research is now based on comparisons of RNA and DNA.
Magnetoencephalography Use in the field Magnetoencephalography > Use in the field MEG is also being used to better localize responses in the brain. The openness of the MEG setup allows external auditory and visual stimuli to be easily introduced. Some movement by the subject is also possible as long as it does not jar the subject's head.
Autogas Converter Autogas > System components > Converter The converter (also known as vaporiser or reducer) is a device designed to change the fuel from a pressurised liquid to a vapour at around atmospheric pressure for delivery to the mixer or vapour phase injectors. Because of the refrigerant characteristic of the fuel, heat must be put into the fuel by the converter. This is usually achieved by having engine coolant circulated through a heat exchanger that transfers heat from that coolant to the LPG. There are two distinctly different basic types of converter for use with mixer type systems.
Risk factors of schizophrenia Other views Risk_factors_of_schizophrenia > Other views The way an individual interprets his or her delusions and hallucinations (e.g. as threatening or as potentially positive) has also been found to influence functioning and recovery in patients.Other lines of work that relate to the self in schizophrenia have linked the disorder to psychological dissociation or abnormal states of awareness and identity as understood from phenomenological perspective, such as in self-disorders.Psychiatrist Tim Crow has argued that schizophrenia may be the evolutionary price we pay for a left brain hemisphere specialization for language. Since psychosis is associated with greater levels of right brain hemisphere activation and a reduction in the usual left brain hemisphere dominance, our language abilities may have evolved at the cost of causing schizophrenia when this system breaks down. In alternative medicine, some practitioners believe that there is a vast number of physical causes for the diagnosis of schizophrenia. While some of these explanations may stretch credulity, others (such as heavy metal poisoning and nutritional imbalances) have been supported at least somewhat by research.
Electrical units Electric current Electric_system > Concepts > Electric current The motion of negatively charged electrons around an electric circuit, one of the most familiar forms of current, is thus deemed positive in the opposite direction to that of the electrons. However, depending on the conditions, an electric current can consist of a flow of charged particles in either direction, or even in both directions at once. The positive-to-negative convention is widely used to simplify this situation.
Architectural Framework Defense industry frameworks Architectural_Framework > Types of enterprise architecture framework > Defense industry frameworks AGATE – the France DGA Architecture Framework DNDAF – the DND/CF Architecture Framework (CAN) DoDAF – the US Department of Defense Architecture Framework MODAF – the UK Ministry of Defence Architecture Framework NAF – the NATO Architecture Framework
Diffraction topography Systematic overview of techniques and imaging conditions Diffraction_topography > Experimental realization – instrumentation > Systematic overview of techniques and imaging conditions The manifold topographic techniques can be categorized according to several criteria. One of them is the distinction between restricted-beam techniques on the one hand (such as section topography or pinhole topography) and extended-beam techniques on the other hand, which use the full width and intensity of the incoming beam. Another, independent distinction is between integrated-wave topography, making use of the full spectrum of incoming X-ray wavelengths and divergences, and plane-wave (monochromatic) topopgraphy, more selective in both wavelengths and divergence. Integrated-wave topography can be realized as either single-crystal or double-crystal topography. Further distinctions include the one between topography in reflection geometry (Bragg-case) and in transmission geometry (Laue case). For a full discussion and a graphical hierarchy of topographic techniques, see .
Signature recognition Summary Signature_recognition Signature recognition is an example of behavioral biometrics that identifies a person based on their handwriting. It can be operated in two different ways: Static: In this mode, users write their signature on paper, and after the writing is complete, it is digitized through an optical scanner or a camera to turn the signature image into bits. The biometric system then recognizes the signature analyzing its shape. This group is also known as "off-line".Dynamic: In this mode, users write their signature in a digitizing tablet, which acquires the signature in real time.
Natronorubrum Scientific books Natronorubrum > Further reading > Scientific books Bergey's Manual of Determinative Bacteriology (8th ed.). Baltimore: The Williams & Wilkins Co. ISBN 0-683-01117-0. == External links ==
Apathy Parkinson's disease Apathy > Medical aspects > Parkinson's disease Overall, ~40% of Parkinson's disease patients suffer from apathy, with prevalence rates varying from 16-62%, depending on the study. Apathy is increasingly recognized to be an important non-motor symptom in Parkinson's disease. It has a significant negative impact on quality of life. In some patients, apathy can be improved by dopaminergic medication. There is also some evidence for a positive effect of cholinesterase inhibitors such as Rivastigmine on apathy. Diminished sensitivity to reward may be a key component of the syndrome in Parkinson's disease.
Bernoulli trial Definition Bernoulli_trial > Definition {\displaystyle q:p.} These can also be expressed as numbers, by dividing, yielding the odds for, o f {\displaystyle o_{f}} , and the odds against, o a {\displaystyle o_{a}}: o f = p / q = p / ( 1 − p ) = ( 1 − q ) / q o a = q / p = ( 1 − p ) / p = q / ( 1 − q ) . {\displaystyle {\begin{aligned}o_{f}&=p/q=p/(1-p)=(1-q)/q\\o_{a}&=q/p=(1-p)/p=q/(1-q).\end{aligned}}} These are multiplicative inverses, so they multiply to 1, with the following relations: o f = 1 / o a , o a = 1 / o f , o f ⋅ o a = 1.
Passive voice Summary Passive_voice Thus, turning an active sense of a verb into a passive sense is a valence-decreasing process ("detransitivizing process"), because it syntactically turns a transitive sense into an intransitive sense. This is not always the case; for example in Japanese a passive-voice construction does not necessarily decrease valence.Many languages have both an active and a passive voice; this allows for greater flexibility in sentence construction, as either the semantic agent or patient may take the syntactic role of subject. The use of passive voice allows speakers to organize stretches of discourse by placing figures other than the agent in subject position. This may be done to foreground the patient, recipient, or other thematic role; it may also be useful when the semantic patient is the topic of on-going discussion. The passive voice may also be used to avoid specifying the agent of an action.
Persistent pulmonary hypertension of the newborn Pathophysiology Persistent_pulmonary_hypertension_of_the_newborn > Pathophysiology Typically, a fetus experiences pulmonary hypertension in utero since it is relying on the placenta for oxygen rather than its lungs. When the fetus is born, it is no longer attached to the placenta and must use the lungs to receive oxygen. To facilitate this change from fetus to newborn, the baby must change from a state of high PVR to low PVR, allowing for increased blood flow to circulate throughout the body. This inability of the newborn to adapt to these changes is caused by various processes, such as: Normal vascular anatomy with functional vasoconstriction: This has a good prognosis, as it is reversible.
Magnetic potential energy Potential energy for electrostatic forces between two bodies Nuclear_potential_energy > Potential energy for electrostatic forces between two bodies The electrostatic force exerted by a charge Q on another charge q separated by a distance r is given by Coulomb's Law where r ^ {\displaystyle \mathbf {\hat {r}} } is a vector of length 1 pointing from Q to q and ε0 is the vacuum permittivity. The work W required to move q from A to any point B in the electrostatic force field is given by the potential function
Photosynthetically active radiation Second law PAR efficiency Photosynthetically_active_radiation_(PAR) > Second law PAR efficiency Besides the amount of radiation reaching a plant in the PAR region of the spectrum, it is also important to consider the quality of such radiation. Radiation reaching a plant contains entropy as well as energy, and combining those two concepts the exergy can be determined. This sort of analysis is known as exergy analysis or second law analysis, and the exergy represents a measure of the useful work, i.e., the useful part of radiation which can be transformed into other forms of energy. The spectral distribution of the exergy of radiation is defined as: E x λ = L λ ( T ) − L λ ( T 0 ) − T 0 {\displaystyle Ex_{\lambda }=L_{\lambda }(T)-L_{\lambda }(T_{0})-T_{0}} One of the advantages of working with the exergy is that it depends not only on the temperature of the emitter (the Sun), T {\displaystyle T} , but also on the temperature of the receiving body (the plant), T 0 {\displaystyle T_{0}} , i.e., it includes the fact that the plant is emitting radiation.
Spectral analyzer Resolution bandwidth Spectrum_analyzer > Typical functionality > Resolution bandwidth Adjusting the bandwidth of this filter allows for the discrimination of signals with closely spaced frequency components, while also changing the measured noise floor. Decreasing the bandwidth of an RBW filter decreases the measured noise floor and vice versa. This is due to higher RBW filters passing more frequency components through to the envelope detector than lower bandwidth RBW filters, therefore a higher RBW causes a higher measured noise floor.
2D computer graphics Summary 2D_computer_graphics 2D computer graphics is the computer-based generation of digital images—mostly from two-dimensional models (such as 2D geometric models, text, and digital images) and by techniques specific to them. It may refer to the branch of computer science that comprises such techniques or to the models themselves. 2D computer graphics are mainly used in applications that were originally developed upon traditional printing and drawing technologies, such as typography, cartography, technical drawing, advertising, etc. In those applications, the two-dimensional image is not just a representation of a real-world object, but an independent artifact with added semantic value; two-dimensional models are therefore preferred, because they give more direct control of the image than 3D computer graphics (whose approach is more akin to photography than to typography). In many domains, such as desktop publishing, engineering, and business, a description of a document based on 2D computer graphics techniques can be much smaller than the corresponding digital image—often by a factor of 1/1000 or more.
Inertia damper Real-world applications and devices Inertia_damper > Real-world applications and devices May use a smooth surface rotating cylinder and a smooth surface stationary interior wall with fluid/gel between. For more forceful motion absorption and higher surface area, a paddle wheel or toothed gear is used, with a similarly ribbed or studded stationary interior wall to more forcefully grip the fluid/gel. == References ==
Feature learning Restricted Boltzmann machine Feature_learning > Multilayer/deep architectures > Restricted Boltzmann machine An RBM can be viewed as a single layer architecture for unsupervised feature learning. In particular, the visible variables correspond to input data, and the hidden variables correspond to feature detectors. The weights can be trained by maximizing the probability of visible variables using Hinton's contrastive divergence (CD) algorithm.In general training RBM by solving the maximization problem tends to result in non-sparse representations. Sparse RBM was proposed to enable sparse representations. The idea is to add a regularization term in the objective function of data likelihood, which penalizes the deviation of the expected hidden variables from a small constant p {\displaystyle p} .
Generalized anxiety disorder Other possible modalities discussed in literature for potential in treating GAD Generalized_anxiety_disorder > Treatment > Pharmacotherapy > Other possible modalities discussed in literature for potential in treating GAD Other modalities that have been academically studied for their potential in treating GAD or symptoms of GAD are summarised below. What follows is a summary of academic findings. Accordingly, none of the following should be taken as offering medical guidance or an opinion as to the safety or efficacy of any of the following modalities.
Inverse consequences Summary Inverse_consequences The term "inverse consequences" or the "Law of Inverse Consequences" refers to results that are the opposite of the expected results as initially intended or planned. One consequence is in the "reverse predicament" of the other.
Empirical mean Distribution of the sample mean Sample_mean_and_covariance > Distribution of the sample mean The arithmetic mean of a population, or population mean, is often denoted μ. The sample mean x ¯ {\displaystyle {\bar {x}}} (the arithmetic mean of a sample of values drawn from the population) makes a good estimator of the population mean, as its expected value is equal to the population mean (that is, it is an unbiased estimator). The sample mean is a random variable, not a constant, since its calculated value will randomly differ depending on which members of the population are sampled, and consequently it will have its own distribution. For a random sample of n independent observations, the expected value of the sample mean is E ⁡ ( x ¯ ) = μ {\displaystyle \operatorname {E} ({\bar {x}})=\mu } and the variance of the sample mean is var ⁡ ( x ¯ ) = σ 2 n .
Modular Equipment Transporter Operation specifications Modular_Equipment_Transporter > Design criteria > Operation specifications Nominal Pulling Speed: 4-7 mph Nominal Draw Bar Pull: 3-5 mph Design Traverse 20,000 ft Capable of Traversing: up to 4" Diameter Rocks Tire Temperatures: -60 °F on deployment 0 °F to 200 °F when parked 70 °F average when rolling Tire Pressure: 1.5 psia
L2 space Properties L2_space > Properties The set, together with the specific inner product ⟨ ⋅ , ⋅ ⟩ 2 {\displaystyle \langle \cdot ,\cdot \rangle _{2}} specify the inner product space. The space of square integrable functions is the L p {\displaystyle L^{p}} space in which p = 2. {\displaystyle p=2.}
Cryogenic particle detector Superconducting tunnel junctions Cryogenic_particle_detector > Types of cryogenic particle detectors > Calorimetric particle detection > Superconducting tunnel junctions The superconducting tunnel junction (STJ) consists of two pieces of superconducting material separated by a very thin (~nanometer) insulating layer. It is also known as a superconductor-insulator-superconductor tunnel junction (SIS) and is a type of a Josephson junction. Cooper pairs can tunnel across the insulating barrier, a phenomenon known as the Josephson effect. Quasiparticles can also tunnel across the barrier, although the quasiparticle current is suppressed for voltages less than twice the superconducting energy gap.
Analytical chemist Spectroscopy Qualitative_chemical_analysis > Instrumental methods > Spectroscopy Spectroscopy measures the interaction of the molecules with electromagnetic radiation. Spectroscopy consists of many different applications such as atomic absorption spectroscopy, atomic emission spectroscopy, ultraviolet-visible spectroscopy, X-ray spectroscopy, fluorescence spectroscopy, infrared spectroscopy, Raman spectroscopy, dual polarization interferometry, nuclear magnetic resonance spectroscopy, photoemission spectroscopy, Mössbauer spectroscopy and so on.
List of incomplete proofs Results later proved rigorously List_of_incomplete_proofs > Results later proved rigorously His paper was not accepted as a complete proof as it contained a gap, and the first complete proofs were given in about 1967 by Baker and Stark. In 1969 Stark showed how to fill the gap in Heegner's paper. In 1954 Igor Shafarevich published a proof that every finite solvable group is a Galois group over the rationals.
Coombs test History Coombs_test > History The Coombs test was first described in 1945 by Cambridge immunologists Robin Coombs (after whom it is named), Arthur Mourant and Rob Race. Historically, it was done in test tubes. Today, it is commonly done using automated solid phase or gel technology.
Translation invariance Geometry Spatial_translation_symmetry > Geometry The vectors a and b can be represented by complex numbers. For two given lattice points, equivalence of choices of a third point to generate a lattice shape is represented by the modular group, see lattice (group). Alternatively, e.g. a rectangle may define the whole object, even if the translation vectors are not perpendicular, if it has two sides parallel to one translation vector, while the other translation vector starting at one side of the rectangle ends at the opposite side.
Old quantum theory De Broglie waves Bohr–Sommerfeld_quantization_conditions > De Broglie waves Today we call them photons (a name coined by Gilbert N. Lewis in a letter to Nature.) Einstein's theoretical argument was based on thermodynamics, on counting the number of states, and so was not completely convincing. Nevertheless, he concluded that light had attributes of both waves and particles, more precisely that an electromagnetic standing wave with frequency ω {\displaystyle \omega } with the quantized energy: E = n ℏ ω {\displaystyle E=n\hbar \omega \,} should be thought of as consisting of n photons each with an energy ℏ ω {\displaystyle \hbar \omega } .
Signalling cascade Examples of biochemical cascades Signalling_cascade > Introduction > Examples of biochemical cascades The pathway has also been implicated in the development of some cancers. Drugs that specifically target hedgehog signaling to fight diseases are being actively developed by a number of pharmaceutical companies. Most biochemical cascades are series of events, in which one event triggers the next, in a linear fashion. Biochemical cascades include: The Complement system The Insulin Signaling Pathway The Sonic hedgehog Signaling Pathway The Wnt signaling pathway The JAK-STAT signaling pathway The Adrenergic receptor Pathways The Acetylcholine receptor Pathways The Mitogen-activated protein kinase cascadeConversely, negative cascades include events that are in a circular fashion, or can cause or be caused by multiple events. Negative cascades include: Ischemic cascade
Gauged supergravity Summary Gauged_supergravity Gauged supergravity is a supergravity theory in which some R-symmetry is gauged such that the gravitinos (superpartners of the graviton) are charged with respect to the gauge fields. Consistency of the supersymmetry transformation often requires the presence of the potential for the scalar fields of the theory, or the cosmological constant if the theory contains no scalar degree of freedom. The gauged supergravity often has the anti-de Sitter space as a supersymmetric vacuum. Notable exception is a six-dimensional N=(1,0) gauged supergravity. "Gauged supergravity" in this sense should be contrasted with Yang–Mills–Einstein supergravity in which some other would-be global symmetries of the theory are gauged and fields other than the gravitinos are charged with respect to the gauge fields.
SimDec Judging the importance of inputs SimDec > How to read SimDec > Judging the importance of inputs If an input variable has no effect on the output, its states (e.g., low & high) would lie on top of each other on the SimDec histogram, occupying fully overlapping ranges of the output. If an input variable has a strong effect and explains most of the variance of the output, the border between its states on the SimDec histogram would be vertical. Such visualization has an important decision-making implication – e.g., if the high state of X can be achieved, it would guarantee a certain range of Y. All cases in-between with low-to-strong effects would show a diagonal border between the states. The less they overlap, the larger the effect of X on Y.While the horizontal displacement of sub-distributions on the SimDec histogram is the key to interpreting the results, the vertical disposition of sub-distributions is just a technical matter of the order of plotting the series of the stacked histogram.
Ray transfer matrix analysis Eigenvalues Ray_transfer_matrix_analysis > Eigenvalues Let m = ( A + D ) 2 {\displaystyle m={\frac {(A+D)}{2}}} , and we have eigenvalues λ 1 , λ 2 = m ± m 2 − 1 {\displaystyle \lambda _{1},\lambda _{2}=m\pm {\sqrt {m^{2}-1}}} . According to the values of λ 1 {\displaystyle \lambda _{1}} and λ 2 {\displaystyle \lambda _{2}} , there are several possible cases. For example: A pair of real eigenvalues: r {\displaystyle r} and r − 1 {\displaystyle r^{-1}} , where r ≠ 1 {\displaystyle r\neq 1} .
Complex society Emergence of complex societies Complex_society > Emergence of complex societies Before human beings developed complex societies, they lived in primitive societies. The historical consensus is that complex societies emerged from primitive societies around 4000-2000 BCE in Egypt, Mesopotamia, the Indus Valley and China. According to traditional theories of how states emerged, the initial spark for the development of complex societies was an agricultural surplus. This economic specialization leads to divisions of labor.
Cross bedding Formation Cross_bedding > Formation Cross-bedding is formed by the downstream migration of bedforms such as ripples or dunes in a flowing fluid. The fluid flow causes sand grains to saltate up the stoss (upstream) side of the bedform and collect at the peak until the angle of repose is reached. At this point, the crest of granular material has grown too large and will be overcome by the force of the moving water, falling down the lee(downstream) side of the dune. Repeated avalanches will eventually form the sedimentary structure known as cross-bedding, with the structure dipping in the direction of the paleocurrent.
Direct recursion Single recursion and multiple recursion Multiple_recursion > Types of recursion > Single recursion and multiple recursion Multiple recursion can sometimes be converted to single recursion (and, if desired, thence to iteration). For example, while computing the Fibonacci sequence naively entails multiple iteration, as each value requires two previous values, it can be computed by single recursion by passing two successive values as parameters. This is more naturally framed as corecursion, building up from the initial values, while tracking two successive values at each step – see corecursion: examples. A more sophisticated example involves using a threaded binary tree, which allows iterative tree traversal, rather than multiple recursion.
Oxophilicity Examples Oxophilicity > Examples In contrast, the anhydrous halides of the later metals tend to hydrate, not hydrolyze, and they often form hydroxides. Reduced complexes of oxophilic metals tend to generate oxides by reaction with oxygen. Typically the oxide-ligand is bridging, e.g. 2 (C5H5)2TiCl + 1/2 O2 → {(C5H5)2TiCl}2OOnly in rare cases do the products of oxygenation feature terminal oxo ligands.
Limiting oxygen concentration Summary Limiting_oxygen_concentration The limiting oxygen concentration (LOC), also known as the minimum oxygen concentration (MOC), is defined as the limiting concentration of oxygen below which combustion is not possible, independent of the concentration of fuel. It is expressed in units of volume percent of oxygen. The LOC varies with pressure and temperature.
Estimation statistics Flaws in hypothesis testing Estimation_statistics > Flaws in hypothesis testing In hypothesis testing, the primary objective of statistical calculations is to obtain a p-value, the probability of seeing an obtained result, or a more extreme result, when assuming the null hypothesis is true. If the p-value is low (usually < 0.05), the statistical practitioner is then encouraged to reject the null hypothesis. Proponents of estimation reject the validity of hypothesis testing for the following reasons, among others: P-values are easily and commonly misinterpreted. For example, the p-value is often mistakenly thought of as 'the probability that the null hypothesis is true.'
Glycolysis Alternative nomenclature Glucose_oxidation_reaction > Alternative nomenclature Some of the metabolites in glycolysis have alternative names and nomenclature. In part, this is because some of them are common to other pathways, such as the Calvin cycle.
2-Pyridone Tautomerisation mechanism B 2-Pyridone > Dimerisation > Tautomerisation mechanism B The direct tautomerisation is not energetically favoured, but a dimerisation followed by a double proton transfer and dissociation of the dimer is a self catalytic path from one tautomer to the other. Protic solvents also mediate the proton transfer during the tautomerisation.
Ozone layer depletion Effects on plant life Ozone_Depletion > Increased UV > Biological effects > Effects on plant life Damage from UVB radiation is more likely to be significant on species interactions than on plants themselves.Another significant impact of ozone depletion on plant life is the stress experienced by plants when exposed to UV radiation. This can cause a decrease in plant growth and an increase in oxidative stress, due to the production of nitric oxide and hydrogen peroxide. Reduction in plant growth will have important consequences in the long-term. It is projected that the plant productivity would decrease by 6% and there will be a reduction in the amount of carbon, plants would capture/sequester from the environment.Moreover, if plants are exposed to high levels of UV radiation, it can elicit the production of harmful volatile organic compounds, like isoprenes. The emission of isoprenes into the air, by plants, can severely impact the environment by adding to air pollution and increasing the amount of carbon in the atmosphere, ultimately contributing to climate change.
VHDL Design VHDL > Design A VHDL simulator is typically an event-driven simulator. This means that each transaction is added to an event queue for a specific scheduled time. E.g. if a signal assignment should occur after 1 nanosecond, the event is added to the queue for time +1ns.
Stephan W. Koch Main research topics Stephan_W._Koch > Main research topics Stephan W. Koch has worked on multiple topics in the general field of semiconductor optics. Before the year 1988, the state-of-the-art description of semiconductor optics and lasers was mainly based on simplified rate-equation approaches which cannot describe the nonequilibrium quantum kinetics of Coulomb-coupled electrons and holes (electronic vacancies in valence band). To go beyond this approach, he was one of the key players to develop the semiconductor Bloch equations (abbreviated as SBEs). Ever since this breakthrough, the SBEs have been expanded to systematically include new many-body effects such as excitation-induced dephasing,non-Markovian effects, and semiconductor excitations with terahertz (abbreviated as THz) fields.
Pseudo Riemannian manifold Applications in physics Pseudo-Riemannian_metric > Lorentzian manifold > Applications in physics After Riemannian manifolds, Lorentzian manifolds form the most important subclass of pseudo-Riemannian manifolds. They are important in applications of general relativity. A principal premise of general relativity is that spacetime can be modeled as a 4-dimensional Lorentzian manifold of signature (3, 1) or, equivalently, (1, 3). Unlike Riemannian manifolds with positive-definite metrics, an indefinite signature allows tangent vectors to be classified into timelike, null or spacelike. With a signature of (p, 1) or (1, q), the manifold is also locally (and possibly globally) time-orientable (see Causal structure).
Negative selection (immunology) T cell tolerance Central_tolerance > Mechanisms of central tolerance > T cell tolerance If they bind a self peptide, then they are signaled to apoptose (process of clonal deletion). The thymic epithelial cells display self antigen to the T cells to test their affinity for self. Transcriptional regulators AIRE and Fezf2 play important roles in the expression of self tissue antigens on the thymic epithelial cells in the thymus.
Neural networks Overview Neural_networks > Overview A biological neural network is composed of a group of chemically connected or functionally associated neurons. A single neuron may be connected to many other neurons and the total number of neurons and connections in a network may be extensive. Connections, called synapses, are usually formed from axons to dendrites, though dendrodendritic synapses and other connections are possible. Apart from electrical signalling, there are other forms of signalling that arise from neurotransmitter diffusion.

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