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Structured analysis and design technique Diagrams Structured_analysis_and_design_technique > SADT topics > Diagrams On the bottom of the box, incoming arrows: means used for the action. On the right-hand side of the box, outgoing arrows: outputs of the action.The semantics of arrows for activities: Inputs enter from the left and represent data or consumables that are needed by the activity. Outputs exit to the right and represent data or products that are produced by the activity.
Xenobiology Summary Xenobiology In practice, it describes novel biological systems and biochemistries that differ from the canonical DNA–RNA-20 amino acid system (see central dogma of molecular biology). For example, instead of DNA or RNA, XB explores nucleic acid analogues, termed xeno nucleic acid (XNA) as information carriers. It also focuses on an expanded genetic code and the incorporation of non-proteinogenic amino acids into proteins.
Rotational–vibrational spectroscopy Heteronuclear diatomic molecules Rotational-vibrational_spectroscopy > Linear molecules > Heteronuclear diatomic molecules The relation between the rotational constants is given by B v = B e q − α ( v + 1 2 ) {\displaystyle B_{v}=B_{eq}-\alpha \left(v+{1 \over 2}\right)} where ν is a vibrational quantum number and α is a vibration-rotation interaction constant which can be calculated when the B values for two different vibrational states can be found. For carbon monoxide req = 113.0 pm.
Dioic acid Linear and cyclic saturated dicarboxylic acids Dioic_acid > Linear and cyclic saturated dicarboxylic acids The general formula for acyclic dicarboxylic acid is HO2C(CH2)nCO2H. The PubChem links gives access to more information on the compounds, including other names, ids, toxicity and safety. Acids from the two-carbon oxalic acid to the ten-member sebacic acid may be remembered using the mnemonic 'Oh My Son, Go And Pray Softly And Silently', and also 'Oh my! Such great Apple Pie, sweet as sugar! '.
Green house gas Works cited Greenhouse_Gas > References > Works cited Blasing, T.J. (February 2013), Current Greenhouse Gas Concentrations, doi:10.3334/CDIAC/atg.032, archived from the original on 16 July 2011, retrieved 30 October 2012 IPCC TAR WG1 (2001), Houghton, J.T. ; Ding, Y.; Griggs, D.J. ; Noguer, M.; van der Linden, P.J.
Mach kernel Mach Mach_kernel > History > Mach Additionally, Mach allowed any program to handle privileges that would normally be given to the operating system only, in order to allow user space programs to handle things like interacting with hardware. Under Mach, and like UNIX, the operating system again becomes primarily a collection of utilities. As with UNIX, Mach keeps the concept of a driver for handling the hardware.
Unnormalized form Summary Unnormalized_form In database normalization, unnormalized form (UNF), also known as an unnormalized relation or non-first normal form (N1NF or NF2), is a database data model (organization of data in a database) which does not meet any of the conditions of database normalization defined by the relational model. Database systems which support unnormalized data are sometimes called non-relational or NoSQL databases. In the relational model, unnormalized relations can be considered the starting point for a process of normalization. It should not be confused with denormalization, where normalization is deliberately compromised for selected tables in a relational database.
Two-alternative forced choice Behavioural experiments Two-alternative_forced_choice > Behavioural experiments A juice reward is then administered after each response. The amount of juice reward is then varied to modulate choice. In a different application, the 2AFC is designed to test discrimination of motion perception.
Watt Origin and adoption as an SI unit Watt > Origin and adoption as an SI unit In this new definition, 1 "absolute" watt = 1.00019 "international" watts. Texts written before 1948 are likely to be using the "international" watt, which implies caution when comparing numerical values from this period with the post-1948 watt. In 1960, the 11th General Conference on Weights and Measures adopted the "absolute" watt into the International System of Units (SI) as the unit of power.
Compiler optimization Code generator optimizations Compiler_optimization > Specific techniques > Code generator optimizations If the coloring fails one variable is "spilled" to memory and the coloring is retried.Instruction selection Most architectures, particularly CISC architectures and those with many addressing modes, offer several different ways of performing a particular operation, using entirely different sequences of instructions. The job of the instruction selector is to do a good job overall of choosing which instructions to implement which operators in the low-level intermediate representation with. For example, on many processors in the 68000 family and on the x86 architecture, complex addressing modes can be used in statements like "lea 25(a1,d5*4), a0", allowing a single instruction to perform a significant amount of arithmetic with less storage.Instruction scheduling Instruction scheduling is an important optimization for modern pipelined processors, which avoids stalls or bubbles in the pipeline by clustering instructions with no dependencies together, while being careful to preserve the original semantics.Rematerialization Rematerialization recalculates a value instead of loading it from memory, preventing a memory access.
MoCl2 Related clusters MoCl2 > Related clusters A variety of clusters are structurally related to 2−. The tungsten analogue is known. Ta and Nb form related clusters where halides are bridge edges of the Ta6 octahedron vs faces. The resulting formula is 4−.
Hierarchical internetworking model Access layer Hierarchical_internetworking_model > Access layer End-stations and servers connect to the enterprise at the access layer. Access layer devices are usually commodity switching platforms, and may or may not provide layer 3 switching services. The traditional focus at the access layer is minimizing "cost-per-port": the amount of investment the enterprise must make for each provisioned Ethernet port. This layer is also called the desktop layer because it focuses on connecting client nodes, such as workstations to the network.
Glossary of representation theory R Glossary_of_representation_theory > R Equivalently, a linear representation is a group action of G on a vector space V that is linear: the action σ: G × V → V {\displaystyle \sigma :G\times V\to V} such that for each g in G, σ g: V → V , v ↦ σ ( g , v ) {\displaystyle \sigma _{g}:V\to V,v\mapsto \sigma (g,v)} is a linear transformation. 3. A virtual representation is an element of the Grothendieck ring of the category of representations. representative The term "representative function" is another term for a matrix coefficient.
Circuit topology (electrical) Hypergraphs Circuit_topology_(electrical) > Graph theory > Active components > Hypergraphs In a directed hypergraph, the tentacles carry labels which are determined by the hyperedge's label. A conventional directed graph can be thought of as a hypergraph with hyperedges each of which has two tentacles. These two tentacles are labelled source and target and usually indicated by an arrow.
Carbon Monoxide Industrial production Carbon_Monoxide > Production > Industrial production 2 CO2 → 2 CO + O2Carbon monoxide is also a byproduct of the reduction of metal oxide ores with carbon, shown in a simplified form as follows: MO + C → M + COCarbon monoxide is also produced by the direct oxidation of carbon in a limited supply of oxygen or air. 2 C + O2 → 2 COSince CO is a gas, the reduction process can be driven by heating, exploiting the positive (favorable) entropy of reaction. The Ellingham diagram shows that CO formation is favored over CO2 in high temperatures.
Immune dysregulation Dysregulation of the immune system in response to toxins Immune_dysregulation > Dysregulation of the immune system in response to toxins However, the ability to break down toxic substances and the resulting impact on the organism is also related to the metabolism and genetic equipment of the individual. Toxins can act directly on the cellular component of immunity, or by their metabolites, or they can promote reactive oxygen species (ROS) in the body, or by depletion of antioxidants or oxidative stress. The most common clinical manifestations are immunosuppression, hypersensitivity, autoimmune diseases, but also support for the Th2 response and the development of allergies, or support for chronic inflammation.
Meningococcal infection Signs and symptoms Neisseria_meningitidis > Signs and symptoms Current guidance in the United Kingdom is that if a case of meningococcal meningitis or septicaemia (infection of the blood) is suspected, intravenous antibiotics should be given and the ill person admitted to the hospital. This means that laboratory tests may be less likely to confirm the presence of Neisseria meningitidis as the antibiotics will dramatically lower the number of bacteria in the body. The UK guidance is based on the idea that the reduced ability to identify the bacteria is outweighed by reduced chance of death.Septicaemia caused by Neisseria meningitidis has received much less public attention than meningococcal meningitis even though septicaemia has been linked to infant deaths.
Local convex hull Summary Local_convex_hull If the local distribution function is a parametric distribution, such as a symmetric bivariate normal distribution then the method is referred to as a kernel method, but more correctly should be designated as a parametric kernel method. On the other hand, if the local kernel element associated with each point is a local convex polygon constructed from the point and its k-1 nearest neighbors, then the method is nonparametric and referred to as a k-LoCoH or fixed point LoCoH method. This is in contrast to r-LoCoH (fixed radius) and a-LoCoH (adaptive radius) methods.
Field-oriented control Technical overview Vector_control_(motor) > Technical overview The induction motor's (d,q) coordinate system can be superimposed to the motor's instantaneous (a,b,c) three-phase sinusoidal system as shown in accompanying image (phases b & c not shown for clarity). Components of the (d,q) system current vector allow conventional control such as proportional and integral, or PI, control, as with a DC motor. Projections associated with the (d,q) coordinate system typically involve: Forward projection from instantaneous currents to (a,b,c) complex stator current space vector representation of the three-phase sinusoidal system.
John Tyndall Main scientific work John_Tyndall > Main scientific work Prior to Tyndall it was widely surmised that the Earth's atmosphere warms the surface in what was later called a greenhouse effect, but he was the first to prove it. The proof was that water vapour strongly absorbed infrared radiation. Three years earlier, in 1856, the American scientist Eunice Newton Foote had announced experiments demonstrating that water vapour and carbon dioxide absorb heat from solar radiation, but she did not differentiate the effects of infrared.
Rocket equation Acceleration-based Classical_rocket_equation > Derivation > Other derivations > Acceleration-based Imagine a rocket at rest in space with no forces exerted on it (Newton's First Law of Motion). From the moment its engine is started (clock set to 0) the rocket expels gas mass at a constant mass flow rate R (kg/s) and at exhaust velocity relative to the rocket ve (m/s). This creates a constant force F propelling the rocket that is equal to R × ve. The rocket is subject to a constant force, but its total mass is decreasing steadily because it is expelling gas.
Gear manufacturing Gear generation Gear_manufacturing > Gear generation In gear generation, the tooth flanks are obtained as an outline of the subsequent positions of the cutter, which resembles in shape the mating gear in the gear pair. There are two machining processes employed shaping and milling. There are several modifications of these processes for different cutting tool used.
Paxos algorithm Basic Paxos when multiple Proposers conflict Paxos_algorithm > Basic Paxos > Graphic representation of the flow of messages in the basic Paxos > Basic Paxos when multiple Proposers conflict OLD LEADER tries 3 | X------------>|->|->| | | Prepare(3) | |<------------X--X--X | | Promise(3,{null,null,null}) | | | | | | | | !! NEW LEADER proposes, denied | | X--------->|->|->| | | Accept! (2,Va) | | |<---------X--X--X | | Nack(3) | | | | | | | | !!
Gravity of Earth Other factors Gravity_of_Earth > Variation in magnitude > Other factors In air or water, objects experience a supporting buoyancy force which reduces the apparent strength of gravity (as measured by an object's weight). The magnitude of the effect depends on the air density (and hence air pressure) or the water density respectively; see Apparent weight for details. The gravitational effects of the Moon and the Sun (also the cause of the tides) have a very small effect on the apparent strength of Earth's gravity, depending on their relative positions; typical variations are 2 µm/s2 (0.2 mGal) over the course of a day.
Yang–Mills equation Physics Yang–Mills_equations > Motivation > Physics The essential points of the work of Yang and Mills are as follows. One assumes that the fundamental description of a physical model is through the use of fields, and derives that under a local gauge transformation (change of local trivialisation of principal bundle), these physical fields must transform in precisely the way that a connection A {\displaystyle A} (in physics, a gauge field) on a principal bundle transforms. The gauge field strength is the curvature F A {\displaystyle F_{A}} of the connection, and the energy of the gauge field is given (up to a constant) by the Yang–Mills action functional YM ⁡ ( A ) = ∫ X ‖ F A ‖ 2 d v o l g .
Trefftz method Introduction Trefftz_method > Introduction The hybrid Trefftz finite-element method has been considerably advanced since its introduction about 30 years ago. The conventional method of finite element analysis involves converting the differential equation that governs the problem into a variational functional from which element nodal properties – known as field variables – can be found. This can be solved by substituting in approximate solutions to the differential equation and generating the finite element stiffness matrix which is combined with all the elements in the continuum to obtain the global stiffness matrix. Application of the relevant boundary conditions to this global matrix, and the subsequent solution of the field variables rounds off the mathematical process, following which numerical computations can be used to solve real life engineering problems.An important aspect of solving the functional requires us to find solutions that satisfy the given boundary conditions and satisfy inter-element continuity since we define independently the properties over each element domain.The hybrid Trefftz method differs from the conventional finite element method in the assumed displacement fields and the formulation of the variational functional.
Bivalent (genetics) Formation Bivalent_(genetics) > Formation This physical strand exchange and the cohesion between the sister chromatids along each chromosome ensure robust pairing of the homologs in diplotene phase. The structure, visible by microscopy, is called a bivalent.
Nuclear weapons design Two-stage thermonuclear Pure_fission_weapon > Two-stage thermonuclear The radiation quickly turns the plastic foam that had been filling the channel into a plasma which is mostly transparent to X-rays, and the radiation is absorbed in the outermost layers of the pusher/tamper surrounding the secondary, which ablates and applies a massive force (much like an inside out rocket engine) causing the fusion fuel capsule to implode much like the pit of the primary. As the secondary implodes a fissile "spark plug" at its center ignites and provides neutrons and heat which enable the lithium deuteride fusion fuel to produce tritium and ignite as well. The fission and fusion chain reactions exchange neutrons with each other and boost the efficiency of both reactions.
Hilbert spaces Lebesgue spaces Complex_Hilbert_space > Examples > Lebesgue spaces Lebesgue spaces are function spaces associated to measure spaces (X, M, μ), where X is a set, M is a σ-algebra of subsets of X, and μ is a countably additive measure on M. Let L2(X, μ) be the space of those complex-valued measurable functions on X for which the Lebesgue integral of the square of the absolute value of the function is finite, i.e., for a function f in L2(X, μ), and where functions are identified if and only if they differ only on a set of measure zero. The inner product of functions f and g in L2(X, μ) is then defined as or where the second form (conjugation of the first element) is commonly found in the theoretical physics literature. For f and g in L2, the integral exists because of the Cauchy–Schwarz inequality, and defines an inner product on the space. Equipped with this inner product, L2 is in fact complete.
Lipogenesis Hormonal regulation Triglyceride_synthesis > Hormonal regulation Acetyl-CoA carboxylase (ACC), converts acetyl-CoA produced by PDH into malonyl-CoA. Malonyl-CoA provides the two-carbon building blocks that are used to create larger fatty acids.
Temperature-compensated balance wheel Summary Balance_wheels The balance wheel and hairspring together form a harmonic oscillator, which due to resonance oscillates preferentially at a certain rate, its resonant frequency or "beat", and resists oscillating at other rates. The combination of the mass of the balance wheel and the elasticity of the spring keep the time between each oscillation or "tick" very constant, accounting for its nearly universal use as the timekeeper in mechanical watches to the present. From its invention in the 14th century until tuning fork and quartz movements became available in the 1960s, virtually every portable timekeeping device used some form of balance wheel.
Oppenheimer (film) Filming Oppenheimer_(film) > Production > Filming Kai Bird visited the set and was impressed by Murphy's performance as Oppenheimer during filming.Filming involved the use of real explosives to recreate the Trinity nuclear test, forgoing the use of computer-generated graphics. When this news first broke online, many fans (aware of Nolan's famous preference for in-camera practical effects) thought it meant he had set off a real atomic bomb. Nolan later remarked that it was both "flattering" and "scary" that his fans would think that of him.
Voluntary muscles Exercise Muscle_loss > Exercise Type II muscle fibers rely on glucogenesis for energy during anaerobic exercise. During anaerobic exercise, type II fibers consume little oxygen, protein and fat, produce large amounts of lactic acid and are fatigable. Many exercises are partially aerobic and anaerobic; for example, soccer and rock climbing.
Two-domain system Domain Archaea Two-domain_system > Classification > Domain Archaea It comprises both prokaryotic and eukaryotic organisms.Archaea Archaea are prokaryotic organisms and some examples are: All methanogens – which produce the gas methane. Most halophiles – which live in very salty water. Most thermoacidophiles – which live in acidic high-temperature water.Eukarya Eukaryotes are those having nucleus in their cells, and are classified into four groups: Protists – an informal taxon for unicellular eukaryotes that include malarial parasites, amoeba, and diatoms. Kingdom Fungi – multicellular eukaryotes such as mushroom, yeast, and mould.
Eyring equation Error propagation formulas Eyring_equation > Error propagation formulas Error propagation formulas for Δ H ‡ {\displaystyle \Delta H^{\ddagger }} and Δ S ‡ {\displaystyle \Delta S^{\ddagger }} have been published.
Solubility constant Dissolution with reaction Solubility_constant > Quantitative aspects > Dissolution with reaction A typical reaction with dissolution involves a weak base, B, dissolving in an acidic aqueous solution. This reaction is very important for pharmaceutical products. Dissolution of weak acids in alkaline media is similarly important. The uncharged molecule usually has lower solubility than the ionic form, so solubility depends on pH and the acid dissociation constant of the solute.
Micro RNA Transcription Micro_RNA > Biogenesis > Transcription Animal miRNAs are initially transcribed as part of one arm of an ~80 nucleotide RNA stem-loop that in turn forms part of a several hundred nucleotide-long miRNA precursor termed a pri-miRNA. When a stem-loop precursor is found in the 3' UTR, a transcript may serve as a pri-miRNA and a mRNA. RNA polymerase III (Pol III) transcribes some miRNAs, especially those with upstream Alu sequences, transfer RNAs (tRNAs), and mammalian wide interspersed repeat (MWIR) promoter units.
Immortal DNA strand hypothesis Evidence Immortal_DNA_strand_hypothesis > Evidence Joshua Merok et al. from the lab of James Sherley engineered mammalian cells with an inducible p53 gene that controls asymmetric divisions. BrdU pulse/chase experiments with these cells demonstrated that chromosomes segregated non-randomly only when the cells were induced to divide asymmetrically like adult stem cells. These asymmetrically dividing cells provide an in vitro model for demonstration and investigation of immortal strand mechanisms.
Quine–Morse set theory MK axioms and ontology Morse–Kelley_set_theory > MK axioms and ontology ∃ y ) ] ) ] . {\displaystyle \exists y)])].} Note that p and s in Power Set and Union are universally, not existentially, quantified, as Class Comprehension suffices to establish the existence of p and s. Power Set and Union only serve to establish that p and s cannot be proper classes. The above axioms are shared with other set theories as follows: ZFC and NBG: Pairing, Power Set, Union, Infinity; NBG (and ZFC, if quantified variables were restricted to sets): Extensionality, Foundation; NBG: Limitation of Size.
Shear force Summary Shear_forces In solid mechanics, shearing forces are unaligned forces acting on one part of a body in a specific direction, and another part of the body in the opposite direction. When the forces are collinear (aligned with each other), they are called tension forces or compression forces. Shear force can also be defined in terms of planes: "If a plane is passed through a body, a force acting along this plane is called a shear force or shearing force."
Standard Gibbs function of formation Summary Standard_Gibbs_function_of_formation The standard Gibbs free energy of formation (Gf°) of a compound is the change of Gibbs free energy that accompanies the formation of 1 mole of a substance in its standard state from its constituent elements in their standard states (the most stable form of the element at 1 bar of pressure and the specified temperature, usually 298.15 K or 25 °C). The table below lists the standard Gibbs function of formation for several elements and chemical compounds and is taken from Lange's Handbook of Chemistry. Note that all values are in kJ/mol. Far more extensive tables can be found in the CRC Handbook of Chemistry and Physics and the NIST JANAF tables. The NIST Chemistry WebBook (see link below) is an online resource that contains standard enthalpy of formation for various compounds along with the standard absolute entropy for these compounds from which the standard Gibbs free energy of formation can be calculated.
Molière radius Summary Molière_radius The Molière radius is a characteristic constant of a material giving the scale of the transverse dimension of the fully contained electromagnetic showers initiated by an incident high energy electron or photon. By definition, it is the radius of a cylinder containing on average 90% of the shower's energy deposition. Two Molière radii contain 95% of the shower's energy deposition.
Carbon Cycle Climate change Carbon_export > Human influence on fast carbon cycle > Climate change Carbon sinks in the land and the ocean each currently take up about one-quarter of anthropogenic carbon emissions each year.These feedbacks are expected to weaken in the future, amplifying the effect of anthropogenic carbon emissions on climate change. The degree to which they will weaken, however, is highly uncertain, with Earth system models predicting a wide range of land and ocean carbon uptakes even under identical atmospheric concentration or emission scenarios. Arctic methane emissions indirectly caused by anthropogenic global warming also affect the carbon cycle and contribute to further warming.
Hamilton equation Optical wave fronts and trajectories Hamilton-Jacobi_theory > Waves and particles > Optical wave fronts and trajectories The HJE establishes a duality between trajectories and wavefronts. For example, in geometrical optics, light can be considered either as “rays” or waves. The wave front can be defined as the surface C t {\textstyle {\cal {C}}_{t}} that the light emitted at time t = 0 {\textstyle t=0} has reached at time t {\textstyle t} . Light rays and wave fronts are dual: if one is known, the other can be deduced.
Isospectral flow Summary Isospectral_problem In mathematics, two linear operators are called isospectral or cospectral if they have the same spectrum. Roughly speaking, they are supposed to have the same sets of eigenvalues, when those are counted with multiplicity. The theory of isospectral operators is markedly different depending on whether the space is finite or infinite dimensional.
Generative adversarial networks Mathematical Generative_adversarial_networks > Definition > Mathematical The discriminator's strategy set is the set of Markov kernels μ D: Ω → P {\displaystyle \mu _{D}:\Omega \to {\mathcal {P}}} , where P {\displaystyle {\mathcal {P}}} is the set of probability measures on {\displaystyle } . The GAN game is a zero-sum game, with objective function The generator aims to minimize the objective, and the discriminator aims to maximize the objective. The generator's task is to approach μ G ≈ μ ref {\displaystyle \mu _{G}\approx \mu _{\text{ref}}} , that is, to match its own output distribution as closely as possible to the reference distribution. The discriminator's task is to output a value close to 1 when the input appears to be from the reference distribution, and to output a value close to 0 when the input looks like it came from the generator distribution.
Aquarium filter Trickle filters Aquarium_filter > Types > Power filters > Trickle filters The water returns to the aquarium like rain.Alternatively, the wet/dry filter may be placed below the tank. In this design, water is fed by gravity to the filter below the aquarium. Prefiltered water is delivered to a perforated plate (drip plate).
Adenylyl-sulfate reductase Nomenclature Adenylyl-sulfate_reductase > Nomenclature This enzyme belongs to the family of oxidoreductases, specifically those acting on a sulfur group of donors with other acceptors. The systematic name of this enzyme class is AMP, sulfite:acceptor oxidoreductase (adenosine-5'-phosphosulfate-forming). Other names in common use include adenosine phosphosulfate reductase, adenosine 5'-phosphosulfate reductase, APS-reductase, APS reductase, AMP, sulfite:(acceptor) oxidoreductase, and (adenosine-5'-phosphosulfate-forming). This enzyme participates in selenium metabolism and sulfur metabolism.
Chemical yield Theoretical, actual, and percent yields Yield_(chemistry) > Theoretical, actual, and percent yields If a reverse reaction occurs, the final state contains both reactants and products in a state of chemical equilibrium. Two or more reactions may occur simultaneously, so that some reactant is converted to undesired side products. Losses occur in the separation and purification of the desired product from the reaction mixture. Impurities are present in the starting material which do not react to give desired product.
Crystallography Summary Crystallography This involved measuring the angles of crystal faces relative to each other and to theoretical reference axes (crystallographic axes), and establishing the symmetry of the crystal in question. The position in 3D space of each crystal face is plotted on a stereographic net such as a Wulff net or Lambert net. The pole to each face is plotted on the net.
Function constant Sorting Anonymous_function > Uses > Sorting Consider this Python code sorting a list of strings by length of the string: The anonymous function in this example is the lambda expression: The anonymous function accepts one argument, x, and returns the length of its argument, which is then used by the sort() method as the criteria for sorting. Basic syntax of a lambda function in Python is The expression returned by the lambda function can be assigned to a variable and used in the code at multiple places. Another example would be sorting items in a list by the name of their class (in Python, everything has a class): Note that 11.2 has class name "float", 10 has class name "int", and 'number' has class name "str". The sorted order is "float", "int", then "str".
Nerve regeneration Central nervous system regeneration Neural_regeneration > Central nervous system regeneration Slower degeneration of the distal segment than that which occurs in the peripheral nervous system also contributes to the inhibitory environment because inhibitory myelin and axonal debris are not cleared away as quickly. All these factors contribute to the formation of what is known as a glial scar, which axons cannot grow across. The proximal segment attempts to regenerate after injury, but its growth is hindered by the environment. It is important to note that central nervous system axons have been proven to regrow in permissive environments; therefore, the primary problem to central nervous system axonal regeneration is crossing or eliminating the inhibitory lesion site. Another problem is that the morphology and functional properties of central nervous system neurons are highly complex, for this reason a neuron functionally identical cannot be replaced by one of another type (Llinás' law).
Molecular oxygen Ozone Monatomic_oxygen > Ozone Triatomic oxygen (ozone, O3) is a very reactive allotrope of oxygen that is a pale blue gas at standard temperature and pressure. Liquid and solid O3 have a deeper blue color than ordinary O2, and they are unstable and explosive. In its gas phase, ozone is destructive to materials like rubber and fabric and is damaging to lung tissue.
Endocrine organ Hormones Endocrine_cell > Function > Hormones The term hormone is sometimes extended to include chemicals produced by cells that affect the same cell (autocrine or intracrine signalling) or nearby cells (paracrine signalling). Hormones are used to communicate between organs and tissues for physiological regulation and behavioral activities, such as digestion, metabolism, respiration, tissue function, sensory perception, sleep, excretion, lactation, stress, growth and development, movement, reproduction, and mood.Hormones affect distant cells by binding to specific receptor proteins in the target cell resulting in a change in cell function. This may lead to cell type-specific responses that include rapid changes to the activity of existing proteins, or slower changes in the expression of target genes. Amino acid–based hormones (amines and peptide or protein hormones) are water-soluble and act on the surface of target cells via signal transduction pathways; steroid hormones, being lipid-soluble, move through the plasma membranes of target cells to act within their nuclei.
50 Hz Rotating machines Power_system_stability > Operating factors > Rotating machines The steadier rotation speed of high-speed machines allowed for satisfactory operation of commutators in rotary converters. The synchronous speed N in RPM is calculated using the formula, N = 120 f P {\displaystyle N={\frac {120f}{P}}\,} where f is the frequency in hertz and P is the number of poles. Direct-current power was not entirely displaced by alternating current and was useful in railway and electrochemical processes. Prior to the development of mercury arc valve rectifiers, rotary converters were used to produce DC power from AC. Like other commutator-type machines, these worked better with lower frequencies.
Carbohydrate catabolism Summary Carbohydrate_catabolism Glucose reacts with oxygen in the following reaction, C6H12O6 + 6O2 → 6CO2 + 6H2O. Carbon dioxide and water are waste products, and the overall reaction is exothermic. The reaction of glucose with oxygen releasing energy in the form of molecules of ATP is therefore one of the most important biochemical pathways found in living organisms.
Inclusion (disability rights) Approaches Inclusion_(disability_rights) > Approaches In short, it is a process that is centered on integrating formerly marginalized individuals into "mainstream" society. This is accomplished by making "the needs and experiences of persons with disabilities an integral part of the design, implementation, monitoring, and evaluation of policies and programs in all political, economic, and societal spheres so that persons with disabilities benefit equally and so that inequality is not perpetuated." In educational settings, it is the practice of placing students with special education services in a general education classroom during specific time periods based on their skills to enable a person with a disability to take part in a "mainstream" environment without added difficulty by creating inclusive settings. For example, education initiatives such as IDEA or No Child Left Behind promote inclusive schooling or mainstreaming for children with disabilities, such as autism, so that they can participate in the community at large.
Planck law Spectral dependence of thermal radiation Planckian_distribution > Physics > Kirchhoff's law of thermal radiation > Spectral dependence of thermal radiation By the Helmholtz reciprocity principle, radiation from the interior of such a body would pass unimpeded, directly to its surrounds without reflection at the interface. In thermodynamic equilibrium, the thermal radiation emitted from such a body would have that unique universal spectral radiance as a function of temperature. This insight is the root of Kirchhoff's law of thermal radiation.
Integrating sphere Structure Integrating_sphere > Structure The theory of the integrating sphere assumes a uniform inside surface with diffuse reflectivity approaching 100%. Openings where light can exit or enter, used for detectors and sources, are normally called ports. The total area of all ports must be small, less than about 5% of the surface area of the sphere, for the theoretical assumptions to be valid.
Neural cryptography Applications Neural_cryptography > Applications Hardware application with multi micro-controllers have been proposed due to the easy implementation of multilayer neural networks in hardware. One example of a public-key protocol is given by Khalil Shihab. He describes the decryption scheme and the public key creation that are based on a backpropagation neural network.
Digital music Conversion process Digital_audio_recorder > Overview > Conversion process The digital signal may be altered through digital signal processing, where it may be filtered or have effects applied. Sample-rate conversion including upsampling and downsampling may be used to change signals that have been encoded with a different sampling rate to a common sampling rate prior to processing. Audio data compression techniques, such as MP3, Advanced Audio Coding, Ogg Vorbis, or FLAC, are commonly employed to reduce the file size.
Outline of cell biology By function Outline_of_cell_biology > Types of cells > By function The largest existing single cells currently known are (fertilized) eggs. Meristemic cell – Undifferentiated plants cells analogous to animal stem cells. Stem cell – Undifferentiated cells found in most multi-cellular organisms which are capable of retaining the ability to reinvigorate themselves through mitotic cell division and can differentiate into a diverse range of specialized cell types.
Co-receptor CCR family of receptors Co-receptor > Some classical examples > CCR family of receptors The HIV envelope glycoprotein GP120 binds to CD4 as its primary receptor, CCR5 then forms a complex with CD4 and HIV, allowing viral entry into the cell. CCR5 is not the only member of the CCR family that allows for HIV infection. Due to the commonality of structures found throughout the family, CCR2b, CCR3, and CCR8 can be utilized by some HIV strains as co-receptors to facilitate infection.
Wiener–Khinchin theorem Discrepancies in terminology Wiener–Khinchin_theorem > Discrepancies in terminology In many textbooks and in much of the technical literature it is tacitly assumed that Fourier inversion of the autocorrelation function and the power spectral density is valid, and the Wiener–Khinchin theorem is stated, very simply, as if it said that the Fourier transform of the autocorrelation function was equal to the power spectral density, ignoring all questions of convergence (Einstein is an example). But the theorem (as stated here) was applied by Norbert Wiener and Aleksandr Khinchin to the sample functions (signals) of wide-sense-stationary random processes, signals whose Fourier transforms do not exist. The whole point of Wiener's contribution was to make sense of the spectral decomposition of the autocorrelation function of a sample function of a wide-sense-stationary random process even when the integrals for the Fourier transform and Fourier inversion do not make sense. Further complicating the issue is that the discrete Fourier transform always exists for digital, finite-length sequences, meaning that the theorem can be blindly applied to calculate autocorrelations of numerical sequences.
Outline of machine learning Machine learning research Machine_learning_algorithms > Machine learning research List of artificial intelligence projects List of datasets for machine learning research
Nonabelian Hodge theorem History Nonabelian_Hodge_correspondence > History The Narasimhan–Seshadri theorem concerns unitary representations of the fundamental group. Nigel Hitchin introduced a notion of a Higgs bundle as an algebraic object which should correspond to complex representations of the fundamental group (in fact the terminology "Higgs bundle" was introduced by Carlos Simpson after the work of Hitchin). The first instance of the nonabelian Hodge theorem was proven by Hitchin, who considered the case of rank two Higgs bundles over a compact Riemann surface.
Bayesian epistemology Beliefs, probability and bets Bayesian_epistemology > Fundamentals > Beliefs, probability and bets So if you know that the objective chance of a coin landing heads is 50% then your credence that the coin will land heads should be 0.5. The axioms of probability together with the principal principle determines the static or synchronic aspect of rationality: what an agent's beliefs should be like when only considering one moment. But rationality also involves a dynamic or diachronic aspect, which comes to play for changing one's credences upon being confronted with new evidence. This aspect is determined by the principle of conditionalization.
Intel VT Intel virtualization (VT-x) X86_virtualization > Hardware-assisted virtualization > Central processing unit > Intel virtualization (VT-x) In 2010, Westmere added support for launching the logical processor directly in real mode – a feature called "unrestricted guest", which requires EPT to work.Since the Haswell microarchitecture (announced in 2013), Intel started to include VMCS shadowing as a technology that accelerates nested virtualization of VMMs. The virtual machine control structure (VMCS) is a data structure in memory that exists exactly once per VM, while it is managed by the VMM. With every change of the execution context between different VMs, the VMCS is restored for the current VM, defining the state of the VM's virtual processor.
Data Access Object Advantages Data_Access_Object > Advantages Technologies like Java Persistence API and Enterprise JavaBeans come built into application servers and can be used in applications that use a Java EE application server. Commercial products such as TopLink are available based on object-relational mapping (ORM). Popular open source ORM software includes Doctrine, Hibernate, iBATIS and JPA implementations such as Apache OpenJPA.
Introduction to general relativity Probing the gravitational field Introduction_to_general_relativity > Geometry and gravitation > Probing the gravitational field In special relativity, parallel geodesics remain parallel. In a gravitational field with tidal effects, this will not, in general, be the case.
Viral marketing Metrics Viral_marketing > Methods and metrics > Metrics Consumers' brand engagement can be measured through the K-factor, the number of followers, friends, registered users, and time spent on the website. Indicators that are more bottom-line oriented focus on consumers' actions after acknowledging the marketing content, including the number of requests for information, samples, or test-drives. Nevertheless, responses to actual call-to-action messages are important, including the conversion rate.
Optical anisotropy Summary Double_refraction Crystals with non-cubic crystal structures are often birefringent, as are plastics under mechanical stress. Birefringence is responsible for the phenomenon of double refraction whereby a ray of light, when incident upon a birefringent material, is split by polarization into two rays taking slightly different paths. This effect was first described by Danish scientist Rasmus Bartholin in 1669, who observed it in calcite crystals which have one of the strongest birefringences. In the 19th century Augustin-Jean Fresnel described the phenomenon in terms of polarization, understanding light as a wave with field components in transverse polarization (perpendicular to the direction of the wave vector). Birefringence plays an important role in achieving phase-matching for a number of nonlinear optical processes.
Wang and Landau algorithm Wang and Landau molecular dynamics: Statistical Temperature Molecular Dynamics (STMD) Wang_and_Landau_algorithm > Wang and Landau molecular dynamics: Statistical Temperature Molecular Dynamics (STMD) As the simulation converges to flat energy sampling, the running estimate T ~ ( E ) {\displaystyle {\tilde {T}}(E)} converges to the true T ( E ) {\displaystyle T(E)} . Technical details including steps to speed convergence are described in and.In STMD T 0 {\displaystyle T_{0}} is called the kinetic temperature as it controls the velocities as usual, but does not enter the configurational sampling, which is unusual. Thus STMD can probe low energies with fast particles.
VMware Current products VMware > Current products The translated code gets stored in spare memory, typically at the end of the address space, which segmentation mechanisms can protect and make invisible. For these reasons, VMware operates dramatically faster than emulators, running at more than 80% of the speed that the virtual guest operating system would run directly on the same hardware. In one study VMware claims a slowdown over native ranging from 0–6 percent for the VMware ESX Server.
NIO ET7 Autonomous driving system NIO_ET7 > Autonomous driving system The autonomous driving system in the Nio ET7 is called Aquila, which uses 33 sensors, including seven 8 MP high-definition cameras, four 3 MP light-sensitive surround-view cameras, a high-resolution LIDAR with a 500 m (1,640.4 ft) range, 5 millimeter-wave radars, 12 ultrasonic radars, and 2 high-precision positioning units. The Aquila autonomous driving system generates 8 gigabytes of data per second which is analysed by an onboard computer called Adam.
Algebraic data types Explanation Algebraic_data_types > Explanation This task may seem easy for the simple patterns above, but with many complex recursive patterns, the task becomes difficult for the average human (or compiler, if it must check arbitrary nested if-else constructs) to handle. Similarly, there may be patterns which never match (i.e., are already covered by prior patterns), and the compiler can also check and issue warnings for these, as they may indicate an error in reasoning.
Derivative-free optimization Introduction Derivative-free_optimization > Introduction The problem to be solved is to numerically optimize an objective function f: A → R {\displaystyle f\colon A\to \mathbb {R} } for some set A {\displaystyle A} (usually A ⊂ R n {\displaystyle A\subset \mathbb {R} ^{n}} ), i.e. find x 0 ∈ A {\displaystyle x_{0}\in A} such that without loss of generality f ( x 0 ) ≤ f ( x ) {\displaystyle f(x_{0})\leq f(x)} for all x ∈ A {\displaystyle x\in A} . When applicable, a common approach is to iteratively improve a parameter guess by local hill-climbing in the objective function landscape. Derivative-based algorithms use derivative information of f {\displaystyle f} to find a good search direction, since for example the gradient gives the direction of steepest ascent. Derivative-based optimization is efficient at finding local optima for continuous-domain smooth single-modal problems.
RF interference EMI in integrated circuits RF_interference > EMI in integrated circuits Integrated circuits are often a source of EMI, but they must usually couple their energy to larger objects such as heatsinks, circuit board planes and cables to radiate significantly.On integrated circuits, important means of reducing EMI are: the use of bypass or decoupling capacitors on each active device (connected across the power supply, as close to the device as possible), rise time control of high-speed signals using series resistors, and IC power supply pin filtering. Shielding is usually a last resort after other techniques have failed, because of the added expense of shielding components such as conductive gaskets. The efficiency of the radiation depends on the height above the ground plane or power plane (at RF, one is as good as the other) and the length of the conductor in relation to the wavelength of the signal component (fundamental frequency, harmonic or transient such as overshoot, undershoot or ringing). At lower frequencies, such as 133 MHz, radiation is almost exclusively via I/O cables; RF noise gets onto the power planes and is coupled to the line drivers via the VCC and GND pins.
Statics Moment about a point Static_structure > Background > Moment of a force > Moment about a point x i j ) {\displaystyle r=\left({\begin{array}{cc}x_{00}&...&x_{0j}\\x_{01}&...&x_{1j}\\...&...&...\\x_{i0}&...&x_{ij}\\\end{array}}\right)} F = ( f 00 . . .
Polysymplectic manifold General and cited references Special_Lagrangian_submanifold > General and cited references Arnold, V. I. (1990). "Ch.1, Symplectic geometry".
List of uncertainty propagation software Software List_of_uncertainty_propagation_software > Software GUM + Monte Carlo. Free restricted educational version available. gum_mc: GUM framework and Monte Carlo method.
Structured analysis and design technique Summary Structured_analysis_and_design_technique Structured analysis and design technique (SADT) is a systems engineering and software engineering methodology for describing systems as a hierarchy of functions. SADT is a structured analysis modelling language, which uses two types of diagrams: activity models and data models. It was developed in the late 1960s by Douglas T. Ross, and was formalized and published as IDEF0 in 1981.
First law of thermodynamics Overview of the weight of evidence for the law First_law_of_thermodynamics > Evidence for the first law of thermodynamics for closed systems > Overview of the weight of evidence for the law The first law of thermodynamics is so general that its predictions cannot all be directly tested. In many properly conducted experiments it has been precisely supported, and never violated. Indeed, within its scope of applicability, the law is so reliably established, that, nowadays, rather than experiment being considered as testing the accuracy of the law, it is more practical and realistic to think of the law as testing the accuracy of experiment. An experimental result that seems to violate the law may be assumed to be inaccurate or wrongly conceived, for example due to failure to account for an important physical factor. Thus, some may regard it as a principle more abstract than a law.
Black-body radiation Temperature relation between a planet and its star Black-body_radiation > Applications > Temperature relation between a planet and its star The power from the Sun that strikes the planet (at the top of the atmosphere) is: P S E = P S e m t ( π R E 2 4 π D 2 ) ( 2 ) {\displaystyle P_{\rm {SE}}=P_{\rm {S\ emt}}\left({\frac {\pi R_{\rm {E}}^{2}}{4\pi D^{2}}}\right)\qquad \qquad (2)} where R E {\displaystyle R_{\rm {E}}\,} is the radius of the planet, and D {\displaystyle D\,} is the distance between the Sun and the planet.Because of its high temperature, the Sun emits to a large extent in the ultraviolet and visible (UV-Vis) frequency range. In this frequency range, the planet reflects a fraction α {\displaystyle \alpha } of this energy where α {\displaystyle \alpha } is the albedo or reflectance of the planet in the UV-Vis range. In other words, the planet absorbs a fraction 1 − α {\displaystyle 1-\alpha } of the Sun's light, and reflects the rest.
Linear belief function Linear regression models Linear_belief_function > Knowledge representation > Linear regression models From representing the six special cases, we see a clear advantage of the moment matrix representation, i.e., it allows a unified representation for seemingly diverse types of knowledge, including linear equations, joint and conditional distributions, and ignorance. The unification is significant not only for knowledge representation in artificial intelligence but also for statistical analysis and engineering computation. For example, the representation treats the typical logical and probabilistic components in statistics — observations, distributions, improper priors (for Bayesian statistics), and linear equation models — not as separate concepts, but as manifestations of a single concept. It allows one to see the inner connections between these concepts or manifestations and to interplay them for computational purposes.
Green Chemistry Synthetic techniques Sustainable_chemistry > Examples > Synthetic techniques A number of important process chemicals can be synthesized in engineered organisms, such as shikimate, a Tamiflu precursor which is fermented by Roche in bacteria. Click chemistry is often cited as a style of chemical synthesis that is consistent with the goals of green chemistry. The concept of 'green pharmacy' has recently been articulated based on similar principles.
Instant indexing Delayed inclusion Instant_indexing > Delayed inclusion Certain search engine services may require an extended period of time for inclusion, which is seen as a delay and causes frustration to website administrators who wish to have their websites appear in search engine results.Delayed inclusion may be due to the size of the index that the service must maintain or due to corporate, political or social policies. Some services, such as Ask.com only index content collected by a crawler program which does not allow for manual adding of content to index.
Nil ring Z Nil_ring > Z zero A zero ring: The ring consisting only of a single element 0 = 1, also called the trivial ring. Sometimes "zero ring" is alternatively used to mean rng of square zero.
Mixed quantum-classical dynamics Use of NA-MQC dynamics Mixed_quantum-classical_dynamics > Use of NA-MQC dynamics In the Born-Oppenheimer approximation, the ensemble of electrons of a molecule or supramolecular system can have several discrete states. The potential energy of each of these electronic states depends on the position of the nuclei, forming multidimensional surfaces. Under usual conditions (room temperature, for instance), the molecular system is in the ground electronic state (the electronic state of lowest energy). In this stationary situation, nuclei and electrons are in equilibrium, and the molecule naturally vibrates near harmonically due to the zero-point energy.
Substitution rule Proof Change_of_variables_formula > Substitution for a single variable > Proof Since f {\displaystyle f} is continuous, it has an antiderivative F {\displaystyle F} . The composite function F ∘ g {\displaystyle F\circ g} is then defined. Since g {\displaystyle g} is differentiable, combining the chain rule and the definition of an antiderivative gives Applying the fundamental theorem of calculus twice gives which is the substitution rule.
Standing Wave Standing wave on a string with two fixed ends Standing_Wave > Mathematical description > Standing wave on a string with two fixed ends This boundary condition is in the form of the Sturm–Liouville formulation. The latter boundary condition is satisfied when sin ⁡ ( 2 π L λ ) = 0 {\displaystyle \sin \left({2\pi L \over \lambda }\right)=0} . L is given, so the boundary condition restricts the wavelength of the standing waves to n = 1 , 2 , 3 , … {\displaystyle n=1,2,3,\ldots } Waves can only form standing waves on this string if they have a wavelength that satisfies this relationship with L. If waves travel with speed v along the string, then equivalently the frequency of the standing waves is restricted to f = v λ = n v 2 L .
Reporter gene Promoter assays Reporter_gene > Promoter assays Reporter genes can be used to assay for the activity of a particular promoter in a cell or organism. In this case there is no separate "gene of interest"; the reporter gene is simply placed under the control of the target promoter and the reporter gene product's activity is quantitatively measured. The results are normally reported relative to the activity under a "consensus" promoter known to induce strong gene expression.
Cartographic design Map types Cartographic_design > Map types Choropleth maps are by far the most popular kind of thematic maps due to the widespread availability of aggregated statistical data (such as census data, but the nature of aggregate data can result in significant misinterpretation issues, such as the Ecological fallacy and the Modifiable areal unit problem, which can be somewhat mitigated by careful design. A Dasymetric map is a hybrid type that uses additional data sources to refine the boundaries of a choropleth map (especially through excluding uninhabited areas), thereby mitigating some of the sources of misinterpretation. A Proportional symbol map visualizes statistical data of point symbols, often circles, using the visual variable of size.
Inattentional blindness Evidence for late selection Inattentional_blindness > The cognition debate: early vs. late selection of attention > Evidence for late selection When photos of objects are shown too quickly for participants to identify, subsequent presentation of those items lead to significantly faster identification in comparison to novel objects.A notable study by Mack and Rock has also revealed that showing a word stimulus differing from the participant's name by one letter did not generally call conscious attention. By simply changing a character, transforming the presented word into the observer's first name, the now highly meaningful stimulus is significantly more likely to be attended to. This suggests that the stimuli are being extensively processed, at least enough to analyze their meaning. These results point to the fact that attentional selection may be determined late in processing.The evidence outlined above suggests that even when stimuli are not processed to the level of conscious attention, they are nonetheless perceptually and cognitively processed, and can indeed exert effects on subsequent behavior.
Microgram Summary Microgram In the metric system, a microgram or microgramme is a unit of mass equal to one millionth (1×10−6) of a gram. The unit symbol is μg according to the International System of Units (SI); the recommended symbol in the United States and United Kingdom when communicating medical information is mcg. In μg the prefix symbol for micro- is the Greek letter μ (mu).
Home automation for the elderly and disabled Disabled population Assistive_domotics > Telehealth implementation > Disabled population Patients with functional disabilities may benefit from telehealth care. According to the World Health Organization, functional limitation refers to the physical or mental conditions, which impair, interfere with, or impede one or more of the individual's major life activities and instrumental activities of daily living.
Antihypertensive agent Patient factors Antihypertensive_drug > Choice of initial medication > Patient factors Race. JNC8 guidelines particularly point out that when used as monotherapy, thiazide diuretics, and calcium channel blockers have been found to be more effective in reducing blood pressure in black hypertensives than β-blockers, ACE inhibitors, or ARBs. Tremor may warrant the use of beta blockers.The JNC8 guidelines indicate reasons to choose one drug over the others for certain individual patients.
Earthquake seismology History Earthquake_seismology > History 340 BCE), and Zhang Heng (132 CE). In 132 CE, Zhang Heng of China's Han dynasty designed the first known seismoscope.In the 17th century, Athanasius Kircher argued that earthquakes were caused by the movement of fire within a system of channels inside the Earth. Martin Lister (1638–1712) and Nicolas Lemery (1645–1715) proposed that earthquakes were caused by chemical explosions within the Earth.The Lisbon earthquake of 1755, coinciding with the general flowering of science in Europe, set in motion intensified scientific attempts to understand the behaviour and causation of earthquakes.
Value at risk Risk measure and risk metric Value_at_risk > Risk measure and risk metric There are many alternative risk measures in finance. Given the inability to use mark-to-market (which uses market prices to define loss) for future performance, loss is often defined (as a substitute) as change in fundamental value.
Deep Learning History Deep_neural_network > History Transformers are also increasingly being used in computer vision.In 1991, Jürgen Schmidhuber also published adversarial neural networks that contest with each other in the form of a zero-sum game, where one network's gain is the other network's loss. The first network is a generative model that models a probability distribution over output patterns. The second network learns by gradient descent to predict the reactions of the environment to these patterns.