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Portable Aqua Unit for Lifesaving Performance Portable_Aqua_Unit_for_Lifesaving > Technology > Performance At about 1.15 metres of water pressure, the water is filtered through the membrane with a pore size of 20 to 100 nm. The device removes bacteria with an efficiency of 99.999% (measurement Institut Fresenius, E. coli and Coliform) and viruses to 99.9% (measured Bonn University, coliphages). A system based on ultrafiltration system (unlike Reverse osmosis based units) is not able to filter out solutes like salts or liquids like mineral oils.
Privacy in education Student expectation of privacy Privacy_in_education > Student expectation of privacy In line with the general meaning of "expectation of privacy," student expectation of privacy refers to a student's inherent right to privacy in the school system. Examples of student expectation of privacy, especially in the pre-collegiate levels, include the protection of a student's academic record from being viewed by anyone other than the academic instructor, the student's parents or guardians, and the students themselves. There have been many legal cases regarding the privacy concerns of pupils' academic records, for example the Owasso Independent School District v. Falvo that was handled by the U.S. Supreme Court in 2002.
Diffeomorphism Surface deformations Diffeomorphism > Examples > Surface deformations {\displaystyle f(x,y)=(u,v).} The total differential of u is d u = ∂ u ∂ x d x + ∂ u ∂ y d y {\displaystyle du={\frac {\partial u}{\partial x}}dx+{\frac {\partial u}{\partial y}}dy} , and similarly for v.Then the image ( d u , d v ) = ( d x , d y ) D f {\displaystyle (du,dv)=(dx,dy)Df} is a linear transformation, fixing the origin, and expressible as the action of a complex number of a particular type. When (dx, dy) is also interpreted as that type of complex number, the action is of complex multiplication in the appropriate complex number plane.
Supervisory control References: Human Supervisory Control Supervisory_control > References: Human Supervisory Control New York: Academic Press. Jones, P. M. and Jasek, C. A. (1997).
Germán Sierra Russian doll renormalization group Germán_Sierra > Research > Russian doll renormalization group In 2003–04, Sierra, in conjunction with A. LeClair and J.M. Román, introduced multiple models exhibiting a Russian doll renormalization group flow, featuring a cyclic nature instead of converging to a fixed point. Among them was a BCS model with pairing scattering phases that break time-reversal symmetry, which was later demonstrated to be solvable using the algebraic Bethe ansatz. Moreover, they put forward two scattering S-matrices exhibiting a cyclic renormalization group (RG) structure, which is related to both the cycle regime of the Kosterlitz-Thouless flow and an analytic extension of the massive sine-Gordon S matrix.
Approximation ratio Hardness of approximation Approximation_algorithm > Hardness of approximation While inapproximability results have been proved since the 1970s, such results were obtained by ad hoc means and no systematic understanding was available at the time. It is only since the 1990 result of Feige, Goldwasser, Lovász, Safra and Szegedy on the inapproximability of Independent Set and the famous PCP theorem, that modern tools for proving inapproximability results were uncovered. The PCP theorem, for example, shows that Johnson's 1974 approximation algorithms for Max SAT, set cover, independent set and coloring all achieve the optimal approximation ratio, assuming P ≠ NP.
Student's t-distribution Integral of Student's probability density function and p-value Student's_t-distribution > Further properties > Integral of Student's probability density function and p-value The function A(t \| ν) is the integral of Student's probability density function, f(t) between −t and t, for t ≥ 0. It thus gives the probability that a value of t less than that calculated from observed data would occur by chance. Therefore, the function A(t \| ν) can be used when testing whether the difference between the means of two sets of data is statistically significant, by calculating the corresponding value of t and the probability of its occurrence if the two sets of data were drawn from the same population. This is used in a variety of situations, particularly in t-tests.
Graph Theory Graph classes Algorithmic_graph_theory > Problems > Graph classes Many problems involve characterizing the members of various classes of graphs. Some examples of such questions are below: Enumerating the members of a class Characterizing a class in terms of forbidden substructures Ascertaining relationships among classes (e.g. does one property of graphs imply another) Finding efficient algorithms to decide membership in a class Finding representations for members of a class
Broad Water Summary Broad_Water Broad Water, or Broadwater (Welsh: Aber Dysynni) is a salt water lagoon near Tywyn, Wales formed from the silted up estuary of the River Dysynni. In the eighteenth and nineteenth centuries, the estuary was used by the shipbuilding industry, as small sailing ships were launched to carry peat from the local peat bogs. This industry was abandoned in the nineteenth century when the estuary became too silted up, forming the lagoon.
Polar organic chemical integrative sampler Theory and modeling Polar_organic_chemical_integrative_sampler > Fundamentals > Theory and modeling To date, a limited number of chemical sampling rates have been determined.Accumulation of chemicals by a POCIS device generally follows first order kinetics. The kinetics are characterized by an initial integrative phase, followed by an equilibrium partitioning phase. During the integrative phase of uptake, a passive sampling device accumulates residues linearly relative to time, assuming constant exposure concentrations.
Flow map Flow phenomena Flow_map > Flow phenomena This is a ratio variable that is similar to, but distinct from the amount of movement. An example would be representing highway traffic levels using mean vehicle speed, or wind velocity.These are not distinct types of maps; a flow map may portray any of all of these aspects simultaneously. The types of phenomena that have been the subject of flow maps are varied. Topics relating to human geography include: migration, travel, international trade, logistics, public utilities (water, sewer, electricity, telecommunications), and traffic, among others. Others relate to physical geography: streamflow, wind, wildlife migration, etc.
Genetic draft Neutral theory of molecular evolution Genetic_hitchhiking > Applications > Neutral theory of molecular evolution The neutral theory of molecular evolution assumes that most new mutations are either deleterious (and quickly purged by selection) or else neutral, with very few being adaptive. It also assumes that the behavior of neutral allele frequencies can be described by the mathematics of genetic drift. Genetic hitchhiking has therefore been viewed as a major challenge to neutral theory, and an explanation for why genome-wide versions of the McDonald–Kreitman test appear to indicate a high proportion of mutations becoming fixed for reasons connected to selection. == References ==
Testing of advanced thermoplastic composite welds Fatigue strength Testing_of_advanced_thermoplastic_composite_welds > Weld testing and analysis > Fatigue strength 1800 cycles/minute are recommended unless otherwise specified. Tests are generally run at ambient temperature and humidity which is specified at 50% relative humidity ±4%, and 23 °C ±1.1 °C. At least 5 S-N curves need to be generated for a welded joint to give a usable range of cyclical loads on the material. The loads need to be varied from a minimal value that is ideally above 2000 cycles, to a load with 10% of the materials max strength.
Zoogleal mat Formation of biofilms Bacterial_mats > Origin and formation > Formation of biofilms The matrix exopolysaccharides can trap QS autoinducers within the biofilm to prevent predator detection and ensure bacterial survival. In addition to the polysaccharides, these matrices may also contain material from the surrounding environment, including but not limited to minerals, soil particles, and blood components, such as erythrocytes and fibrin. The final stage of biofilm formation is known as development, and is the stage in which the biofilm is established and may only change in shape and size. The development of a biofilm may allow for an aggregate cell colony (or colonies) to be increasingly tolerant or resistant to antibiotics. Cell-cell communication or quorum sensing has been shown to be involved in the formation of biofilm in several bacterial species.
Firefly (cache coherence protocol) Processor-side Requests Firefly_(cache_coherence_protocol) > Processor-side Requests Processor-side requests or CPU requests are the accesses that the processor makes to its own caches. These may be classified into 4 types of requests namely: PrRdMiss: Processor side request to read a cache block that does not reside in the cache. PrRdHit: Processor side request to read a cache block that already resides in the cache. PrWtHit: Processor side request to write to a cache block that already resides in the cache. PrWtMiss: Processor side request to write to a cache block that does not reside in the cache.
BRST quantization The Kugo–Ojima answer to unitarity questions BRST_supersymmetry > The BRST operator and asymptotic Fock space > The Kugo–Ojima answer to unitarity questions The properties of the other fields we have added are fundamentally analytical rather than geometric. The bias we have introduced towards connections with ∂ μ A μ = 0 {\displaystyle \partial ^{\mu }A_{\mu }=0} is gauge-dependent and has no particular geometrical significance. The anti-ghost c ¯ {\displaystyle {\bar {c}}} is nothing but a Lagrange multiplier for the gauge fixing term, and the properties of the scalar field B are entirely dictated by the relationship δ c ¯ = i δ λ B {\displaystyle \delta {\bar {c}}=i\delta \lambda B} .
Business agility Comparison with complex systems Business_agility > Topics in agile enterprise studies > Comparison with complex systems Co-evolution is a key process through which the enterprise learns from experience and adapts. The agile enterprise is constantly evolving in concert with (and in reaction to) external environmental factors.
Process Automation System The background and technology Process_Automation_System > The background and technology In the absence of process automation, plant operators have to physically monitor performance values and the quality of outputs to determine the best settings on which to run the production equipment. Maintenance is carried out at set intervals. This generally results in operational inefficiency and unsafe operating conditions.
Discriminant function analysis Practical use Linear_Discriminant_Analysis > Practical use In practice, the class means and covariances are not known. They can, however, be estimated from the training set. Either the maximum likelihood estimate or the maximum a posteriori estimate may be used in place of the exact value in the above equations. Although the estimates of the covariance may be considered optimal in some sense, this does not mean that the resulting discriminant obtained by substituting these values is optimal in any sense, even if the assumption of normally distributed classes is correct.
Public opinion on climate change Economic Factors Public_opinion_on_climate_change > Influences on individual opinion > Economic Factors Development of climate change policies is influenced by economic conditions. For a long period of time, such conditions were seen to play an important role in influencing political behavior. Economic issues and environmental issues are often seen as a trade-off since something that helps one was believed to negatively affect the other. Accordingly, the environment is usually seen as a problem that is not as big and crucial as the economy.
State equation Overview JWL_equation_of_state > Overview In most cases this model will comprise some empirical parameters that are usually adjusted to measurement data. Equations of state can also describe solids, including the transition of solids from one crystalline state to another. Equations of state are also used for the modeling of the state of matter in the interior of stars, including neutron stars, dense matter (quark–gluon plasmas) and radiation fields.
Anaerobic digestate Methanogenic digestate Anaerobic_digestate > Methanogenic digestate During syntrophic methanogens bacteria belonging mainly to the Clostridia class oxidize acetate into hydrogen and CO2, which are successively exploited by hydrogenotrophic Archaea for the methanogens. The methanogenic microbes are fairly sensitive to pH changes and prefer a range from 5.0-8.5 depending on the species.
Fluorescence spectroscopy Analysis of data Fluorescence_spectroscopy > Analysis of data Correction of all these instrumental factors for getting a ‘standard’ spectrum is a tedious process, which is only applied in practice when it is strictly necessary. This is the case when measuring the quantum yield or when finding the wavelength with the highest emission intensity for instance. As mentioned earlier, distortions arise from the sample as well.
Glossary of genetics (0–L) C Glossary_of_gene_expression_terms > C The term is commonly used in medical genetics in the context of a disease-causing recessive allele. CCAAT box Also CAAT box or CAT box.
Rigid motion segmentation Problems Rigid_motion_segmentation > Problems These mismatched feature points from the objects and the background often introduce outliers. The presence of image noise and outliers further affect the accuracy of structure from motion (SFM) estimation. Another issue is that of motion models or motion representations.
Time-space continuum Summary Space-time_continuum In physics, spacetime is any mathematical model that fuses the three dimensions of space and the one dimension of time into a single four-dimensional continuum. Spacetime diagrams are useful in visualizing and understanding relativistic effects such as how different observers perceive where and when events occur. Until the turn of the 20th century, the assumption had been that the three-dimensional geometry of the universe (its description in terms of locations, shapes, distances, and directions) was distinct from time (the measurement of when events occur within the universe).
Regulator gene Summary Regulatory_gene They are usually constantly expressed so the cell always has a supply of repressor molecules on hand. Inducers cause repressor proteins to change shape or otherwise become unable to bind DNA, allowing RNA polymerase to continue transcription.
First degree atrioventricular block Causes First-degree_atrioventricular_block > Causes The most common causes of first-degree heart block are AV nodal disease, enhanced vagal tone (for example in athletes), myocarditis, acute myocardial infarction (especially acute inferior MI), electrolyte disturbances and medication. The medications that most commonly cause first-degree heart block are those that increase the refractory time of the AV node, thereby slowing AV conduction. These include calcium channel blockers, beta-blockers, cardiac glycosides, and anything that increases cholinergic activity such as cholinesterase inhibitors.
Artificial heart valves Advantages of mechanical valves Bioprosthetic_heart_valve > Mechanical valves > Advantages of mechanical valves The major advantage of mechanical valves over bioprosthetic valves is their greater durability. Made from metal and/or pyrolytic carbon, they can last 20–30 years.
Parallel algorithms for minimum spanning trees Kruskal's algorithm Parallel_algorithms_for_minimum_spanning_trees > Kruskal's algorithm Kruskal's MST algorithm utilises the cycle property of MSTs. A high-level pseudocode representation is provided below. T ← {\displaystyle T\gets } forest with every vertex in its own subtree foreach ( u , v ) ∈ E {\displaystyle (u,v)\in E} in ascending order of weight if u {\displaystyle u} and v {\displaystyle v} in different subtrees of T {\displaystyle T} T ← T ∪ { ( u , v ) } {\displaystyle T\gets T\cup \{(u,v)\}} return T The subtrees of T {\displaystyle T} are stored in union-find data structures, which is why checking whether or not two vertices are in the same subtree is possible in amortised O ( α ( m , n ) ) {\displaystyle O(\alpha (m,n))} where α ( m , n ) {\displaystyle \alpha (m,n)} is the inverse Ackermann function. Thus the total runtime of the algorithm is in O ( s o r t ( n ) + α ( n ) ) {\displaystyle O(sort(n)+\alpha (n))} . Here α ( n ) {\displaystyle \alpha (n)} denotes the single-valued inverse Ackermann function, for which any realistic input yields an integer less than five.
Ranschburg effect Short-term memory input and output Ranschburg_effect > Findings > Short-term memory input and output During the input process of information within the short-term memory, the encoding, attentional, and perceptual processes play an important role in the ability to accurately output and recall a sequence. Failure to appropriately encode or perceive a repeated item can produce the Ranschburg effect. Output processes within the short-term memory include memory and retrieval, and can also contribute substantially to the production of the Ranschburg effect.Due to the correlative relationship between output interference and the production of the Ranschburg effect, output interference is demonstrated to be a significant contributor to recall inhibition.
Tutte polynomial Exact computation Tutte_polynomial > Computational complexity > Exact computation In his paper on the dichotomy for planar graphs, Vertigan claims (in his conclusion) that the same result holds when further restricted to graphs with vertex degree at most three, save for the point T G ( 0 , − 2 ) {\displaystyle T_{G}(0,-2)} , which counts nowhere-zero Z3-flows and is computable in polynomial time.These results contain several notable special cases. For example, the problem of computing the partition function of the Ising model is #P-hard in general, even though celebrated algorithms of Onsager and Fisher solve it for planar lattices. Also, the Jones polynomial is #P-hard to compute. Finally, computing the number of four-colorings of a planar graph is #P-complete, even though the decision problem is trivial by the four color theorem. In contrast, it is easy to see that counting the number of three-colorings for planar graphs is #P-complete because the decision problem is known to be NP-complete via a parsimonious reduction.
Adaptor proteins, vesicular transport Formation of transport vesicles Adaptor_proteins,_vesicular_transport > Formation of transport vesicles The best characterized type of vesicle is the clathrin coated vesicle (CCV). The formation of a COPII vesicle at the endoplasmic reticulum and its transport to the Golgi body. The involvement of the heterotetramer of COPI is similar to that of the AP/clathrin situation, but the coat of COPI is not closely related to the coats of either CCVs or COPII vesicles. AP-5 is associated with 2 proteins, SPG11 and SPG15, which have some structural similarity to clathrin, and may form the coat around the AP-5 complex, but the ultrastructure of that coat is not known.
Distant Early Warning Line Operations Distant_Early_Warning_Line > Operations Service buildings, garages, connecting roads, storage tanks, and perhaps an aircraft hangar completed the community. Drifting snow was a constant menace.
Atelocyanobacterium thalassa Life cycle Atelocyanobacterium_thalassa > Life cycle The lifecycle of A. thalassa is not well understood. As an obligate endosymbiont, A. thalassa is thought to be unable to survive outside of the host, suggesting its entire life cycle takes place inside of the host. The division and replication of A. thalassa are at least partially under the control of the host cell. It is thought that a signal transduction pathway exists to regulate the amount of A. thalassa cells within the host to ensure a sufficient amount of A. thalassa cells are supplied to the host's daughter cell during cell division.
Mechanical systems Structural components Mechanical_systems > Machine elements > Structural components A number of machine elements provide important structural functions such as the frame, bearings, splines, spring and seals. The recognition that the frame of a mechanism is an important machine element changed the name three-bar linkage into four-bar linkage. Frames are generally assembled from truss or beam elements.
Glossary of electrical and electronics engineering I Glossary_of_electrical_and_electronics_engineering > I impulse responseThe response of a network to a sudden narrow pulse input. incandescent light bulbA device that uses a fine wire filament heated by an electric current to make light...and heat. induction coilAn early name for a transformer; a type of transformer for high-voltage uses.
Electromotive Force Distinction with potential difference Electromotive_Force > Distinction with potential difference Although an electrical potential difference (voltage) is sometimes called an emf, they are formally distinct concepts: Potential difference is a more general term that includes emf. Emf is the cause of a potential difference. In a circuit of a voltage source and a resistor, the sum of the source's applied voltage plus the ohmic voltage drop through the resistor is zero. But the resistor provides no emf, only the voltage source does: For a circuit using a battery source, the emf is due solely to the chemical forces in the battery.
Newton's theorem of revolving orbits Newton's derivation Newton's_theorem_of_revolving_orbits > Derivations > Newton's derivation Newton's derivation is found in Section IX of his Principia, specifically Propositions 43–45. His derivations of these Propositions are based largely on geometry. Proposition 43; Problem 30It is required to make a body move in a curve that revolves about the center of force in the same manner as another body in the same curve at rest.Newton's derivation of Proposition 43 depends on his Proposition 2, derived earlier in the Principia.
Groundwater hydrology Other methods Hydrogeology > Calculation of groundwater flow > Numerical methods > Other methods These include mesh-free methods like the Analytic Element Method (AEM) and the Boundary Element Method (BEM), which are closer to analytic solutions, but they do approximate the groundwater flow equation in some way. The BEM and AEM exactly solve the groundwater flow equation (perfect mass balance), while approximating the boundary conditions. These methods are more exact and can be much more elegant solutions (like analytic methods are), but have not seen as widespread use outside academic and research groups yet.
Instant indexing Criticisms Instant_indexing > Criticisms Over time, if a website is popular or authoritative, it is assumed that other websites will eventually link to it. If a search engine service provides instant indexing, it bypasses this quality control mechanism by not requiring incoming links. This infers that the search engine's service produces lower quality results. Select search services that offer such a service typically also offer paid inclusion, also referred to as inorganic search. This may reduce the quality of search results.
Space Time Continuum Energy and momentum conservation Lorentz_interval > Basic mathematics of spacetime > Conservation laws > Energy and momentum conservation In the case of a completely inelastic collision with total loss of kinetic energy, the outgoing velocities of the rebounding particles will be zero. : 241–245 Newtonian momenta, calculated as p = m v {\displaystyle p=mv} , fail to behave properly under Lorentzian transformation. The linear transformation of velocities v ′ = v − u {\displaystyle v'=v-u} is replaced by the highly nonlinear v ′ = ( v − u ) / ( 1 − v u c 2 ) {\displaystyle v^{\prime }=(v-u){\Big /}\left(1-{\frac {vu}{c^{2}}}\right)} so that a calculation demonstrating conservation of momentum in one frame will be invalid in other frames.
Superfactorial Properties Superfactorial > Properties Just as the factorials can be continuously interpolated by the gamma function, the superfactorials can be continuously interpolated by the Barnes G-function.According to an analogue of Wilson's theorem on the behavior of factorials modulo prime numbers, when p {\displaystyle p} is an odd prime number where ! ! {\displaystyle !!}
Caustic (optics) Computer graphics Caustic_(optics) > Computer graphics In computer graphics, most modern rendering systems support caustics. Some of them even support volumetric caustics. This is accomplished by raytracing the possible paths of a light beam, accounting for the refraction and reflection. Photon mapping is one implementation of this.
Poincaré–Bendixson theorem Theorem Poincaré–Bendixson_theorem > Theorem Given a differentiable real dynamical system defined on an open subset of the plane, every non-empty compact ω-limit set of an orbit, which contains only finitely many fixed points, is either a fixed point, a periodic orbit, or a connected set composed of a finite number of fixed points together with homoclinic and heteroclinic orbits connecting these.Moreover, there is at most one orbit connecting different fixed points in the same direction. However, there could be countably many homoclinic orbits connecting one fixed point. A weaker version of the theorem was originally conceived by Henri Poincaré (1892), although he lacked a complete proof which was later given by Ivar Bendixson (1901).
Low-alloy steel Material science High-alloy_steel > Material science Molybdenum helps to resist embrittlement. Zirconium, cerium, and calcium increase toughness by controlling the shape of inclusions.
Climate sensitivity State dependence Climate_sensitivity > State dependence If a tipping point is crossed, climate sensitivity is expected to change at the time scale of the subsystem that hits its tipping point. Especially if there are multiple interacting tipping points, the transition of climate to a new state may be difficult to reverse.The two most common definitions of climate sensitivity specify the climate state: the ECS and the TCR are defined for a doubling with respect to the CO2 levels in the pre-industrial era. Because of potential changes in climate sensitivity, the climate system may warm by a different amount after a second doubling of CO2 from after a first doubling. The effect of any change in climate sensitivity is expected to be small or negligible in the first century after additional CO2 is released into the atmosphere.
Energy transition Renewable energy Energy_transition > Key technologies and approaches > Renewable energy However, because of its heavy dependence on geography and the generally high environmental and social impact of hydroelectric power plants, the growth potential of this technology is limited. Wind and solar power are considered more scalable, but still require vast quantities of land and materials. They have higher potential for growth.
RNA World RNA as an enzyme RNA_World > Properties of RNA > RNA as an enzyme Amino acid-RNA ligation The ability to conjugate an amino acid to the 3'-end of an RNA in order to use its chemical groups or provide a long-branched aliphatic side-chain. Peptide bond formation The ability to catalyse the formation of peptide bonds between amino acids to produce short peptides or longer proteins. This is done in modern cells by ribosomes, a complex of several RNA molecules known as rRNA together with many proteins.
Split-complex number Geometry Split-complex_number > Geometry While analogous to ordinary orthogonality, particularly as it is known with ordinary complex number arithmetic, this condition is more subtle. It forms the basis for the simultaneous hyperplane concept in spacetime. The analogue of Euler's formula for the split-complex numbers is This formula can be derived from a power series expansion using the fact that cosh has only even powers while that for sinh has odd powers.
Google Wave Features Google_Wave > Features The ability to show messages as they are typed could be disabled, similar to conventional instant messaging.The ability to modify a wave at any location let users create collaborative documents, edited in a manner akin to wikis. Waves could easily link to other waves. In many respects, it was a more advanced forum.
Mobile Security Security in operating systems Mobile_Security > Countermeasures > Security in operating systems This could occur if a process managed to reach an area allocated to other processes, where it could write in the memory of a process with rights superior to its own (with 'root' in the worst case) and perform actions beyond its permissions. It would suffice to insert function calls are authorized by the privileges of the malicious application.Development through runtime environments Software is often developed in high-level languages, which can control what is being done by a running program. For example, Java virtual machines continuously monitor the actions of the execution threads they manage, monitor and assign resources, and prevent malicious actions. Buffer overflows can be prevented by these controls.
Free fatty acid receptor 2 Type 1 diabetes Free_fatty_acid_receptor_2 > FFAR2 functions and actions > Diabetes > Type 1 diabetes Ffar2 gene knockout mice (i.e., mice that have had their Ffar2 genes removed or inactivated) have decreased pancreatic beta cell masses at birth and throughout adulthood but do not develop diabetes. However, they do develop defective insulin secretion, glucose intolerance (a prediabetic condition in humans manifested by elevated blood glucose levels), and obesity. This mouse model has some but not all of the features found in human type 1 diabetes. In particular, human type 1 diabetes is at least partly a genetically predisposed autoimmune disease in which an individual's immune system causes inflammation in their pancreatic islets that injures their beta, alpha, and other cells.
Opposite number Summary Unary_minus In mathematics, the additive inverse of a number a (sometimes called the opposite of a) is the number that, when added to a, yields zero. The operation taking a number to its additive inverse is known as sign change or negation. For a real number, it reverses its sign: the additive inverse (opposite number) of a positive number is negative, and the additive inverse of a negative number is positive. Zero is the additive inverse of itself.
Indeterminate form Summary Indeterminate_form In each case, if the limits of the numerator and denominator are substituted, the resulting expression is 0 / 0 {\displaystyle 0/0} , which is indeterminate. In this sense, 0 / 0 {\displaystyle 0/0} can take on the values 0 {\displaystyle 0~} , 1 {\displaystyle 1} , or ∞ {\displaystyle \infty } , by appropriate choices of functions to put in the numerator and denominator. A pair of functions for which the limit is any particular given value may in fact be found.
Operating Systems History General-purpose_operating_system > History It is said that Alan Turing was a master of this on the early Manchester Mark 1 machine, and he was already deriving the primitive conception of an operating system from the principles of the universal Turing machine.Later machines came with libraries of programs, which would be linked to a user's program to assist in operations such as input and output and compiling (generating machine code from human-readable symbolic code). This was the genesis of the modern-day operating system. However, machines still ran a single job at a time.
Flash player Streaming protocols Flash_player > Features > Streaming protocols HTTP: Support for communicating with web servers using HTTP requests and POST data. However, only websites that explicitly allow Flash to connect to them can be accessed via HTTP or sockets, to prevent Flash being used as a tool for cross-site request forgery, cross-site scripting, DNS rebinding, and denial-of-service attacks. Websites must host a certain XML file termed a cross domain policy, allowing or denying Flash content from specific websites to connect to them. Certain websites, such as Digg, Flickr, and Photobucket already host a cross domain policy that permits Flash content to access their website via HTTP.
Trace tree Summary Trace_tree A trace tree is a data structure that is used in the runtime compilation of programming code. Trace trees are used in tracing just-in-time compilation where tracing is used during code execution to look for hot spots before compilation. When those hot spots are entered again the compiled code is run instead.
Directory-based cache coherence Sparse directory format Directory-based_cache_coherence > Sparse directory format A cache only stores a small subset of blocks in main memory at a particular time. Hence most of the entries in the directory will belong to uncached blocks. In the sparse directory format the wastage is reduced by storing only the cached blocks in the directory. Consider a processor with a cache size of 64KB with a block size of 32 bytes and the main memory size to be 4MB.
Feedback amplifier Overview Negative_feedback_amplifier > Overview Feedback amplifiers share these properties:Pros: Can increase or decrease input impedance (depending on type of feedback). Can increase or decrease output impedance (depending on type of feedback). Reduces total distortion if sufficiently applied (increases linearity).
Hand gestures Made with other body parts Hand_gestures > Made with other body parts When shaken once firmly, it is an expression of strong agreement such as "Indeed" or "Yes sir." When shaken quickly the person is indicating a desire to move along with the topic. Orant, a gesture made during prayer in which the hands are raised with palms facing outward.
Electric displacement field Summary Electric_displacement_field In physics, the electric displacement field (denoted by D) or electric induction is a vector field that appears in Maxwell's equations. It accounts for the electromagnetic effects of polarization and that of an electric field, combining the two in an auxiliary field. It plays a major role in topics such as the capacitance of a material, as well the response of dielectrics to electric field, and how shapes can change due to electric fields in piezoelectricity or flexoelectricity as well as the creation of voltages and charge transfer due to elastic strains. In any material, if there is an inversion center then the charge at, for instance, + x {\displaystyle +x} and − x {\displaystyle -x} are the same.
Cray-1 Vector machines Cray-1 > Background > Vector machines In the STAR, new instructions essentially wrote the loops for the user. The user told the machine where in memory the list of numbers was stored, then fed in a single instruction a(1..1000000) = addv b(1..1000000), c(1..1000000). At first glance it appears the savings are limited; in this case the machine fetches and decodes only a single instruction instead of 1,000,000, thereby saving 1,000,000 fetches and decodes, perhaps one-fourth of the overall time. The real savings are not so obvious.
OpenMP Pros and cons OpenMP > Pros and cons Incremental parallelism: can work on one part of the program at one time, no dramatic change to code is needed. Unified code for both serial and parallel applications: OpenMP constructs are treated as comments when sequential compilers are used. Original (serial) code statements need not, in general, be modified when parallelized with OpenMP.
Reliability modeling The importance of language Reliable_system_design > Reliability prediction and improvement > The importance of language (Ring et al. 2000) For part/system failures, reliability engineers should concentrate more on the "why and how", rather that predicting "when". Understanding "why" a failure has occurred (e.g. due to over-stressed components or manufacturing issues) is far more likely to lead to improvement in the designs and processes used than quantifying "when" a failure is likely to occur (e.g. via determining MTBF).
Robotic sensors Summary Robotic_sensors Robotic sensors are used to estimate a robot's condition and environment. These signals are passed to a controller to enable appropriate behavior.Sensors in robots are based on the functions of human sensory organs. Robots require extensive information about their environment in order to function effectively.
Natural logarithm History Natural_logarithms > History An early mention of the natural logarithm was by Nicholas Mercator in his work Logarithmotechnia, published in 1668, although the mathematics teacher John Speidell had already compiled a table of what in fact were effectively natural logarithms in 1619. It has been said that Speidell's logarithms were to the base e, but this is not entirely true due to complications with the values being expressed as integers. : 152
Super-prime Summary Super-prime Their proof relies on a result resembling Bertrand's postulate, stating that (after the larger gap between super-primes 5 and 11) each super-prime number is less than twice its predecessor in the sequence. Broughan & Barnett (2009) show that there are x ( log ⁡ x ) 2 + O ( x log ⁡ log ⁡ x ( log ⁡ x ) 3 ) {\displaystyle {\frac {x}{(\log x)^{2}}}+O\left({\frac {x\log \log x}{(\log x)^{3}}}\right)} super-primes up to x. This can be used to show that the set of all super-primes is small. One can also define "higher-order" primeness much the same way and obtain analogous sequences of primes (Fernandez 1999). A variation on this theme is the sequence of prime numbers with palindromic prime indices, beginning with 3, 5, 11, 17, 31, 547, 739, 877, 1087, 1153, 2081, 2381, ... (sequence A124173 in the OEIS).
Logit (unit) Conversions Decibel_scale > Definition > Conversions Since logarithm differences measured in these units often represent power ratios and root-power ratios, values for both are shown below. The bel is traditionally used as a unit of logarithmic power ratio, while the neper is used for logarithmic root-power (amplitude) ratio.
List of mathematical symbols by subject Complex numbers List_of_mathematical_symbols_by_subject > Numbers > Complex numbers Remark: real and imaginary parts of a complex number are often also denoted by Re {\displaystyle \operatorname {Re} } and Im {\displaystyle \operatorname {Im} } .
Convergence-divergence zone Arborescences of CDZ Convergence-divergence_zone > Arborescences of CDZ It can thus make a synthesis of detection and production capabilities of all the CDZs thus recruited. To make a model of the CDZ system, we distinguish in the nervous system a peripheral part and a central one, with a gradual progression from the periphery to the center. The periphery includes all sources of perception: the feeling of the outside and inside, emotions and actions.
Light field microscopy Light field generation Light_field_microscopy > Light field generation A light field is generated by placing a microlens array at the intermediate image plane of the objective (or the rear focal plane of an optional relay lens) and is further captured by placing the camera sensor at the rear focal plane of the microlenses. As a result, the coordinates of the microlenses ( s , t ) {\displaystyle (s,t)} conjugate with those on the object plane (if additional relay lenses are added, then on the front focal plane of the objective) ( s ′ , t ′ ) {\displaystyle (s',t')} ; the coordinates of the pixels behind each microlens ( u , v ) {\displaystyle (u,v)} conjugate with those on the objective plane ( u ′ , v ′ ) {\displaystyle (u',v')} . For uniformity and convenience, we shall call the plane ( s ′ , t ′ ) {\displaystyle (s',t')} the original focus plane in this article. Correspondingly, f {\displaystyle f} is the focal length of the microlenses (i.e., the distance between microlens array plane and the sensor plane). In addition, the apertures and the focal-length of each lens and the dimensions of the sensor and microlens array should all be properly chosen to ensure that there is neither overlap nor empty areas between adjacent subimages behind the corresponding microlenses.
Semantic model Place/transition net Abstract_model > Modelling techniques > Place/transition net Also known as Petri nets, this conceptual modeling technique allows a system to be constructed with elements that can be described by direct mathematical means. The petri net, because of its nondeterministic execution properties and well defined mathematical theory, is a useful technique for modeling concurrent system behavior, i.e. simultaneous process executions.
Linearity Linear polynomials Linearity > In mathematics > Linear polynomials In a different usage to the above definition, a polynomial of degree 1 is said to be linear, because the graph of a function of that form is a straight line.Over the reals, a simple example of a linear equation is given by: y = m x + b {\displaystyle y=mx+b\ } where m is often called the slope or gradient, and b the y-intercept, which gives the point of intersection between the graph of the function and the y-axis. Note that this usage of the term linear is not the same as in the section above, because linear polynomials over the real numbers do not in general satisfy either additivity or homogeneity. In fact, they do so if and only if the constant term – b in the example – equals 0. If b ≠ 0, the function is called an affine function (see in greater generality affine transformation). Linear algebra is the branch of mathematics concerned with systems of linear equations.
Speed of Light Summary Speed_of_light_in_vacuum The speed of light can be used in time of flight measurements to measure large distances to extremely high precision. Ole Rømer first demonstrated in 1676 that light does not travel instantaneously by studying the apparent motion of Jupiter's moon Io. Progressively more accurate measurements of its speed came over the following centuries.
Precursor messenger RNA Regulation Precursor_RNA > Production > Regulation A number of factors contribute to the activation and inhibition of transcription and therefore regulate the production of primary transcripts from a given DNA template. Activation of RNA polymerase activity to produce primary transcripts is often controlled by sequences of DNA called enhancers. Transcription factors, proteins that bind to DNA elements to either activate or repress transcription, bind to enhancers and recruit enzymes that alter nucleosome components, causing DNA to be either more or less accessible to RNA polymerase. The unique combinations of either activating or inhibiting transcription factors that bind to enhancer DNA regions determine whether or not the gene that enhancer interacts with is activated for transcription or not.
Self ligation Class II elastics Self_ligation > Class II elastics Class 2 elastics are used from the lower first molar to the upper canine tooth. They can be used for many different reasons, such as Class 2 malocclusions, to reinforce anchorage in a case where an extraction has been done, to allow the maxillary incisors to move backwards, and to correct midline deviation and allow buccal movement of backward-tipped lower incisors. Orthodontists generally use 12-16 oz elastics (3/16") in extraction cases or 2× 6 oz elastics on either side of the mouth (3/16"), but in non extraction cases 16-20 oz elastics (3/16") or 2× 8 oz elastics are used. It is very important to know the side effects of Class II elastics before using them in an orthodontic treatment. The following are the effects of Class 2 elastics: Extrusion of upper incisors Extrusion of lower first molar Flaring of the lower incisors Distal movement of the upper teeth and mesial movement of the lower teeth Steepening of the occlusal plane
Respiration in plant Efficiency of ATP production Aerobic_metabolism > Efficiency of ATP production The above value of 3 H+/ATP for the synthase assumes that the synthase translocates 9 protons, and produces 3 ATP, per rotation. The number of protons depends on the number of c subunits in the Fo c-ring, and it is now known that this is 10 in yeast Fo and 8 for vertebrates. Including one H+ for the transport reactions, this means that synthesis of one ATP requires 1 + 10/3 = 4.33 protons in yeast and 1 + 8/3 = 3.67 in vertebrates. This would imply that in human mitochondria the 10 protons from oxidizing NADH would produce 2.72 ATP (instead of 2.5) and the 6 protons from oxidizing succinate or ubiquinol would produce 1.64 ATP (instead of 1.5). This is consistent with experimental results within the margin of error described in a recent review.The total ATP yield in ethanol or lactic acid fermentation is only 2 molecules coming from glycolysis, because pyruvate is not transferred to the mitochondrion and finally oxidized to the carbon dioxide (CO2), but reduced to ethanol or lactic acid in the cytoplasm.
Quadratic funding Sybil attacks Quadratic_voting > Criticisms of quadratic voting mechanisms > Sybil attacks With one of its priorities being an open, peer-to-peer network, an anti-sybil identification software is a requirement to implement widespread quadratic voting.Some future possible avenues of inquiries include to investigate more intersectional proof of personhood systems that aren't directly blockchain-based. For example, extending the web of trust by having a protocol that verifies proof of identities using social interactions would allow a community of users to assign corresponding levels of trusts to different candidates in relation with others. However, this would require a fully decentralized system. This web-of-trust protocol could even expand to allowing candidates to provide proof of personhood by physical attendance, which could lead to trusted clusters that grow into communities.
Lactocillin Function in Human Body Lactocillin > Function in Human Body Lactocillin is seen to be very functional in killing certain pathogens. The minimum inhibitory concentration (MIC) of an antibiotic is the lowest concentration of an antibiotic needed to inhibit the growth of a bacteria. The MIC was calculated for many different bacteria that commonly infect human vaginas. This approach makes sense, as a non-pathogenic bacterium found in the vaginal microbiota might provide a benefit to the host, such as resistance to potential pathogens that commonly infect that area of the body, because the host’s survival is essential for the bacteria’s survival.Growth was observed at multiple different concentrations to obtain the MIC of lactocillin for different pathogens.
Control (management) Organizational and operational control Control_(management) > Classifications > Organizational and operational control The direction for organizational control comes from the goals and strategic plans of the organization. General plans are translated into specific performance measures such as share of the market, earnings, return on investment, and budgets. The process of organizational control is to review and evaluate the performance of the system against these established norms.
Annual growth rate Calculations Annual_growth_rate > Economics > Calculations When evaluating the comparatives, one might say that results in Year 2 were, for example, 110% of those in Year 1. To convert this figure to a growth rate, one need only subtract 100%. The periods considered are often years, but any time-frame can be chosen.
Monoprotic acid Arrhenius acids Monobasic_acid > Definitions and concepts > Arrhenius acids This decreases the concentration of hydronium because the ions react to form H2O molecules: H3O+(aq) + OH−(aq) ⇌ H2O(liq) + H2O(liq)Due to this equilibrium, any increase in the concentration of hydronium is accompanied by a decrease in the concentration of hydroxide. Thus, an Arrhenius acid could also be said to be one that decreases hydroxide concentration, while an Arrhenius base increases it. In an acidic solution, the concentration of hydronium ions is greater than 10−7 moles per liter. Since pH is defined as the negative logarithm of the concentration of hydronium ions, acidic solutions thus have a pH of less than 7.
History of variational principles in physics In quantum mechanics History_of_variational_principles_in_physics > 20th century > In quantum mechanics Several approaches were also considered for quantum mechanics. Inspired by 1933 paper by Paul Dirac, Richard Feynman developed 1948 the path integral formulation, that linked the Lagrangian formalism with the Hamiltonian formalism of quantum mechanics. In quantum chemistry and condensed matter physics, variational methods were developed to study atoms, molecules, nuclei and solids under a quantum mechanical framework. These include Hartree–Fock method, the density matrix renormalization group, and the Ritz method.
Pseudo-covariance matrix Two-dimensional infrared spectroscopy Pseudo-covariance_matrix > Applications > Two-dimensional infrared spectroscopy Two-dimensional infrared spectroscopy employs correlation analysis to obtain 2D spectra of the condensed phase. There are two versions of this analysis: synchronous and asynchronous. Mathematically, the former is expressed in terms of the sample covariance matrix and the technique is equivalent to covariance mapping.
Church–Turing thesis The thesis as a definition Church–Turing_thesis > History > The thesis as a definition The thesis can be viewed as nothing but an ordinary mathematical definition. Comments by Gödel on the subject suggest this view, e.g. "the correct definition of mechanical computability was established beyond any doubt by Turing". The case for viewing the thesis as nothing more than a definition is made explicitly by Robert I. Soare, where it is also argued that Turing's definition of computability is no less likely to be correct than the epsilon-delta definition of a continuous function.
BRST symmetry Gauge fixing and perturbation theory BRST_supersymmetry > Gauge transformations in QFT > Gauge fixing and perturbation theory To use the Dyson series to calculate anything, one needs more than a gauge-invariant Lagrangian density; one also needs the quantization and gauge fixing prescriptions that enter into the Feynman rules of the theory. The Dyson series produces infinite integrals of various kinds when applied to the Hamiltonian of a particular QFT.
Landiolol Uses Landiolol > Uses The efficacy and safety of landiolol in septic shock has been investigated in a multi-center prospective randomized controlled trial, and the results of the study have been published in the renown Journal Lancet Respiratory in 2020, demonstrating clinical impact of landiolol in sepsis patients through significant reduction of new-onset arrhythmia and keeping the patients within the target heart rate range. Furthermore, landiolol demonstrated a positive clinical impact regarding ventilation-free days, ICU-free days and hospital-free days. Patients in the landiolol group had a survival rate of 88% by day 28, in contrast to a mortality rate of 20% in the control group by day 28.
Tight frame Motivating example: computing a basis from a linearly dependent set Tight_frame > Definition and motivation > Motivating example: computing a basis from a linearly dependent set There are some problems with this plan: Removing arbitrary vectors from the set may cause it to be unable to span V {\displaystyle V} before it becomes linearly independent. Even if it is possible to devise a specific way to remove vectors from the set until it becomes a basis, this approach may become unfeasible in practice if the set is large or infinite. In some applications, it may be an advantage to use more vectors than necessary to represent v {\displaystyle \mathbf {v} } .
Neo (The Matrix) The Matrix Resurrections Neo_(The_Matrix) > Fictional character biography > The Matrix Resurrections One day, a man known as "Morpheus" approaches Neo with the red pill, but agents and a police force storm the building where Neo works in order to kill Morpheus; who is revealed to be a rogue agent who opened his mind and decided to help Neo destroy the Matrix. Morpheus kills several police officers while Neo's boss picks up an officer's gun and once again becomes Agent Smith. The attack was revealed to be a dream, and Neo was still in his therapist's room.
Sleep–wake cycle In plants Sleep–wake_cycles > In plants Gene expression of CCA1 and LHY oscillates and peaks in the early morning, whereas TOC1 gene expression oscillates and peaks in the early evening. While it was previously hypothesised that these three genes model a negative feedback loop in which over-expressed CCA1 and LHY repress TOC1 and over-expressed TOC1 is a positive regulator of CCA1 and LHY, it was shown in 2012 by Andrew Millar and others that TOC1, in fact, serves as a repressor not only of CCA1, LHY, and PRR7 and 9 in the morning loop but also of GI and ELF4 in the evening loop. This finding and further computational modeling of TOC1 gene functions and interactions suggest a reframing of the plant circadian clock as a triple negative-component repressilator model rather than the positive/negative-element feedback loop characterizing the clock in mammals.In 2018, researchers found that the expression of PRR5 and TOC1 hnRNA nascent transcripts follows the same oscillatory pattern as processed mRNA transcripts rhythmically in A. thaliana.
Chronic relapsing inflammatory optic neuropathy Treatment Chronic_relapsing_inflammatory_optic_neuritis > Treatment 3. Long-term phase: To avoid adverse effects of long-term steroids and to avoid relapse of disease, physicians can transition to a steroid-sparing agent. B-cell depleting therapy, azathioprine, methotrexate, cyclophosphamide, mycophenolate, IVIG, plasma exchange, cyclosporine, and infliximab have been used.Visual acuity is dramatically worse with CRION than other forms of optic neuritis. Treatment with corticosteroids induces prompt relief of pain and improved vision. At times, patients obtain complete restoration of vision, although exact success rates are unknown.
Limit cycles Applications Limit_cycle > Applications Limit cycles are important in many scientific applications where systems with self-sustained oscillations are modelled. Some examples include: Aerodynamic limit-cycle oscillations The Hodgkin–Huxley model for action potentials in neurons. The Sel'kov model of glycolysis. The daily oscillations in gene expression, hormone levels and body temperature of animals, which are part of the circadian rhythm, although this is contradicted by more recent evidence.
Cardiac excitation-contraction coupling Heart rate Cardiac_excitation-contraction_coupling > Heart rate Heart rate is affected by nerves. Sympathetic nerves, coming from the spinal cord, increase heart rate, whereas parasympathetic nerves (branching from the vagus nerves) work to decrease it.Sympathetic nerves work by releasing a protein (neurotransmitter) called noradrenaline which binds to a specific receptor (beta 1 adrenoceptor) located in the sarcolemma and the t-tubule membrane of cardiac cells. This activates a protein, called a G-protein and results in a series of reactions (known as a cyclic AMP pathway) that leads to the production of a molecule called cAMP (cyclic adenosine monophosphate). In the SAN cAMP binds to an ion channel involved in action potential initiation, speeding up the production of the action potential (see sinoatrial node for more detail).
Queue (abstract data type) Purely functional implementation Queue_(abstract_data_type) > Purely functional implementation Queues can also be implemented as a purely functional data structure. There are two implementations. The first one only achieves O ( 1 ) {\displaystyle O(1)} per operation on average. That is, the amortized time is O ( 1 ) {\displaystyle O(1)} , but individual operations can take O ( n ) {\displaystyle O(n)} where n is the number of elements in the queue. The second implementation is called a real-time queue and it allows the queue to be persistent with operations in O(1) worst-case time. It is a more complex implementation and requires lazy lists with memoization.
Blankenship–Oporowski conjecture Relation to other graph invariants Book_embedding > Properties > Relation to other graph invariants This can be formalized by considering an arbitrary sequence of push and pop operations on a stack, and forming a graph in which the stack operations correspond to the vertices of the graph, placed in sequence order along the spine of a book embedding. Then, if one draws an edge from each pop operation that pops an object x from the stack, to the previous push operation that pushed x, the resulting graph will automatically have a one-page embedding. For this reason, the page number of a graph has also been called its stack number.
Discrete rate simulation Compared to discrete-event and continuous simulation Discrete_rate_simulation > Compared to discrete-event and continuous simulation Another difference is that discrete event simulation models are overwhelmingly concerned with the status of system entities (discrete objects moving through the system) while discrete rate simulation models are concerned with the status (quantity and location) of homogeneous flow. For rate-based systems, discrete rate simulation has faster computational times and is more accurate in calculating mass balance compared to discrete event simulation. Discrete rate simulation is also similar to continuous simulation in that it simulates homogeneous flow.
Algorithm analysis Cost models Run-time_analysis > Cost models For example, if the numbers involved in a computation may be arbitrarily large, the time required by a single addition can no longer be assumed to be constant. Two cost models are generally used: the uniform cost model, also called unit-cost model (and similar variations), assigns a constant cost to every machine operation, regardless of the size of the numbers involved the logarithmic cost model, also called logarithmic-cost measurement (and similar variations), assigns a cost to every machine operation proportional to the number of bits involvedThe latter is more cumbersome to use, so it's only employed when necessary, for example in the analysis of arbitrary-precision arithmetic algorithms, like those used in cryptography. A key point which is often overlooked is that published lower bounds for problems are often given for a model of computation that is more restricted than the set of operations that you could use in practice and therefore there are algorithms that are faster than what would naively be thought possible.
Progressive systemic sclerosis Kidney disease Systemic_scleroderma > Treatment > Kidney disease An elevated serum creatinine level is not a contraindication for ACE inhibitors in this population, and slight elevations in creatinine are common during drug initiation. Scleroderma renal crisis, the occurrence of acute kidney injury, and malignant hypertension (very high blood pressure with evidence of organ damage) in people with scleroderma are effectively treated with drugs from the class of the ACE inhibitors. The benefit of ACE inhibitors extends even to those who have to commence dialysis to treat their kidney disease, and may give sufficient benefit to allow the discontinuation of renal replacement therapy.
P16 (gene) Role in carcinogenesis Protein_P16 > Clinical significance > Role in carcinogenesis Mutations resulting in deletion or reduction of function of the CDKN2A gene are associated with increased risk of a wide range of cancers, and alterations of the gene are frequently seen in cancer cell lines. Examples include: Pancreatic adenocarcinoma is often associated with mutations in the CDKN2A gene.Carriers of germline mutations in CDKN2A have, besides their high risks of melanoma, also increased risks of pancreatic, lung, laryngeal and oropharyngeal cancers. Tobacco smoking increases the carriers’ susceptibility for such non-melanoma cancers.Homozygous deletions of p16 are frequently found in esophageal cancer and gastric cancer cell lines.Germline mutations in CDKN2A are associated with an increased susceptibility to develop skin cancer.Hypermethylation of tumor suppressor genes has been implicated in various cancers. In 2013, a meta-analysis revealed an increased frequency of DNA methylation of the p16 gene in esophageal cancer.

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