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Subsurface bacteria Sediments Subsurface_bacteria > Habitats > Ocean floor > Sediments Upwelling brings nutrient-rich water to the surface, stimulating abundant growth of phytoplankton, which then settles to the bottom (a phenomenon known as the biological pump). Thus, there is a lot of organic material in the sediments, and all the oxygen is used up in its consumption.
Bandwidth (matrix theory) Band form of sparse matrices Bandwidth_(linear_algebra) > Band form of sparse matrices There are, however, matrices for which the reverse Cuthill–McKee algorithm performs better. There are many other methods in use. The problem of finding a representation of a matrix with minimal bandwidth by means of permutations of rows and columns is NP-hard.
Traversal Using Relay NAT Protocol Traversal_Using_Relays_around_NAT > Protocol The Allocate request asks the TURN server to allocate some of its resources for the client so that it may contact a peer. If allocation is possible, the server allocates an address for the client to use as a relay, and sends the client an "Allocation Successful" response, which contains an "allocated relayed transport address" located at the TURN server. Second, the client sends in a CreatePermissions request to the TURN server to create a permissions check system for peer-server communications.
Child psychology Main research methods Child_psychologist > Research methods and designs > Main research methods This method allows for strong inferences to be made of causal relationships between the manipulation of one or more independent variables and subsequent behavior, as measured by the dependent variable. The advantage of using this research method is that it permits determination of cause-and-effect relationships among variables. On the other hand, the limitation is that data obtained in an artificial environment may lack generalizability.
Medicinal properties Assessing the quality of evidence Evidence_based > Methods > Assessing the quality of evidence In other words, the probability is very low that further research will completely change the presented conclusions. Moderate Quality Evidence: The authors are confident that the presented estimate lies close to the true value, but it is also possible that it may be substantially different. In other words, further research may completely change the conclusions.
Fourier heat conduction equation Intensive-property representation Fourier_heat_conduction_equation > Conductance > Intensive-property representation Fourier's law can also be stated as: analogous to Ohm's law, I = V / R {\displaystyle I=V/R} or I = V G . {\displaystyle I=VG.} The reciprocal of conductance is resistance, R, given by: analogous to Ohm's law, R = V / I . {\displaystyle R=V/I.} The rules for combining resistances and conductances (in series and parallel) are the same for both heat flow and electric current.
Viral entry Aftermath Viral_entry > Aftermath Once a virus is in a cell, it will activate formation of proteins (either by itself or using the host) to gain full control of the host cell, if it is able to. Control mechanisms include the suppression of intrinsic cell defenses, suppression of cell signaling and suppression of host cellular transcription and translation. Often, it is these cytotoxic effects that lead to the death and decline of a cell infected by a virus.
NMR tube Sample preparation NMR_tube > Sample preparation Protein NMR is usually performed in a 90% H2O (or buffer)/10% D2O mixture. The sample may be sonicated or agitated to aid dissolution, and solids are removed via filtering through a plug of celite layered on a cotton wool plug in a Pasteur pipette, directly into the NMR tube. The NMR tube is then usually sealed with a polyethylene cap, but can be flame sealed or sealed with a Teflon 'Schlenk' tap or even a very small rubber septum. Parafilm may be wrapped around the cap to reduce solvent evaporation.
Orbital station-keeping Geostationary orbit Orbital_station_keeping > Geostationary orbit When this North-South movement gets too large a steerable antenna is needed to track the spacecraft. An example of this is Artemis.To save weight, it is crucial for GEO satellites to have the most fuel-efficient propulsion system. Almost all modern satellites are therefore employing a high specific impulse system like plasma or ion thrusters.
Fixed-parameter algorithm Summary Fixed-parameter_tractability In computer science, parameterized complexity is a branch of computational complexity theory that focuses on classifying computational problems according to their inherent difficulty with respect to multiple parameters of the input or output. The complexity of a problem is then measured as a function of those parameters. This allows the classification of NP-hard problems on a finer scale than in the classical setting, where the complexity of a problem is only measured as a function of the number of bits in the input. This appears to have been first demonstrated in Gurevich, Stockmeyer & Vishkin (1984).
Symmetries in general relativity Summary Symmetries_in_general_relativity Spacetime symmetries are features of spacetime that can be described as exhibiting some form of symmetry. The role of symmetry in physics is important in simplifying solutions to many problems. Spacetime symmetries are used in the study of exact solutions of Einstein's field equations of general relativity. Spacetime symmetries are distinguished from internal symmetries.
61 (number) In mathematics 61_(number) > In mathematics 61 is: the 18th prime number. a twin prime with 59. a cuban prime of the form p = x3 − y3/x − y, where x = y + 1. the smallest proper prime, a prime p which ends in the digit 1 in base 10 and whose reciprocal in base 10 has a repeating sequence with length p − 1. In such primes, each digit 0, 1, ..., 9 appears in the repeating sequence the same number of times as does each other digit (namely, p − 1/10 times).
Posetal category Summary Posetal_category When the commutative diagrams of a category are interpreted as a typed equational theory whose objects are the types, a codiscrete posetal category corresponds to an inconsistent theory understood as one satisfying the axiom x = y at all types. Viewing a 2-category as an enriched category whose hom-objects are categories, the hom-objects of any extension of a posetal category to a 2-category having the same 1-cells are monoids. Some lattice-theoretic structures are definable as posetal categories of a certain kind, usually with the stronger assumption of being skeletal.
Inclusion (education) Broader approach: social and cultural inclusion Inclusive_education > Broader approach: social and cultural inclusion Although inclusion is generally associated with elementary and secondary education, it is also applicable in postsecondary education. According to UNESCO, inclusion "is increasingly understood more broadly as a reform that supports and welcomes diversity amongst all learners." Under this broader definition of inclusion, steps should also be taken to eliminate discrimination and provide accommodations for all students who are at a disadvantage because of some reason other than disability.
Generative adversarial networks CycleGAN Generative_adversarial_networks > Variants > GANs with more than 2 players > CycleGAN CycleGAN is an architecture for performing translations between two domains, such as between photos of horses and photos of zebras, or photos of night cities and photos of day cities. The CycleGAN game is defined as follows:There are two probability spaces ( Ω X , μ X ) , ( Ω Y , μ Y ) {\displaystyle (\Omega _{X},\mu _{X}),(\Omega _{Y},\mu _{Y})} , corresponding to the two domains needed for translations fore-and-back. There are 4 players in 2 teams: generators G X: Ω X → Ω Y , G Y: Ω Y → Ω X {\displaystyle G_{X}:\Omega _{X}\to \Omega _{Y},G_{Y}:\Omega _{Y}\to \Omega _{X}} , and discriminators D X: Ω X → , D Y: Ω Y → {\displaystyle D_{X}:\Omega _{X}\to ,D_{Y}:\Omega _{Y}\to } . The objective function is where λ {\displaystyle \lambda } is a positive adjustable parameter, L G A N {\displaystyle L_{GAN}} is the GAN game objective, and L c y c l e {\displaystyle L_{cycle}} is the cycle consistency loss:The generators aim to minimize the objective, and the discriminators aim to maximize it: Unlike previous work like pix2pix, which requires paired training data, cycleGAN requires no paired data. For example, to train a pix2pix model to turn a summer scenery photo to winter scenery photo and back, the dataset must contain pairs of the same place in summer and winter, shot at the same angle; cycleGAN would only need a set of summer scenery photos, and an unrelated set of winter scenery photos.
Euclidean Algorithm Visualization Euclid's_algorithm > Description > Visualization The sequence ends when there is no residual rectangle, i.e., when the square tiles cover the previous residual rectangle exactly. The length of the sides of the smallest square tile is the GCD of the dimensions of the original rectangle. For example, the smallest square tile in the adjacent figure is 21×21 (shown in red), and 21 is the GCD of 1071 and 462, the dimensions of the original rectangle (shown in green).
Scale parameter Definition Scale_parameter > Definition If the probability density exists for all values of the complete parameter set, then the density (as a function of the scale parameter only) satisfies f s ( x ) = f ( x / s ) / s , {\displaystyle f_{s}(x)=f(x/s)/s,\!} where f is the density of a standardized version of the density, i.e. f ( x ) ≡ f s = 1 ( x ) {\displaystyle f(x)\equiv f_{s=1}(x)} . An estimator of a scale parameter is called an estimator of scale.
Apparent molar property Relation to the activity coefficient of an electrolyte and its solvation shell number Apparent_molar_property > Relation to the activity coefficient of an electrolyte and its solvation shell number The ratio ra between the apparent molar volume of a dissolved electrolyte in a concentrated solution and the molar volume of the solvent (water) can be linked to the statistical component of the activity coefficient γ s {\displaystyle \gamma _{s}} of the electrolyte and its solvation shell number h: ln ⁡ γ s = h − ν ν ln ⁡ ( 1 + b r a 55.5 ) − h ν ln ⁡ ( 1 − b r a 55.5 ) + b r a ( r a + h − ν ) 55.5 ( 1 + b r a 55.5 ) {\displaystyle \ln \gamma _{s}={\frac {h-\nu }{\nu }}\ln(1+{\frac {br_{a}}{55.5}})-{\frac {h}{\nu }}\ln(1-{\frac {br_{a}}{55.5}})+{\frac {br_{a}(r_{a}+h-\nu )}{55.5(1+{\frac {br_{a}}{55.5}})}}} ,where ν is the number of ions due to dissociation of the electrolyte, and b is the molality as above.
Photosynthetic reaction centre Photosystem I Photosynthetic_reaction_centre > In Cyanobacteria and plants > Photosystem I After the electron has left Photosystem II it is transferred to a cytochrome b6f complex and then to plastocyanin, a blue copper protein and electron carrier. The plastocyanin complex carries the electron that will neutralize the pair in the next reaction center, Photosystem I. As with Photosystem II and the bacterial reaction center, a pair of chlorophyll a molecules initiates photoinduced charge separation. This pair is referred to as P700, where 700 is a reference to the wavelength at which the chlorophyll molecules absorb light maximally. The P700 lies in the center of the protein.
DNAPrint Genomics AncestrybyDNA DNAPrint_Genomics > AncestrybyDNA Typically, these markers are considered "observable variations" due to the fact that the variations can be located on the DNA.Autosomal DNA tests like AncestrybyDNA are used to identify people with whom the DNA donor shares ancestors. The process involves identifying large, shared chunks of DNA between individuals. These "shared chunks'' are indicators of some kind of relatively-recent shared inheritance.
Chang and Roberts algorithm The algorithm Chang_and_Roberts_algorithm > The algorithm It creates an election message containing its UID. It then sends this message clockwise to its neighbour. Every time a process sends or forwards an election message, the process also marks itself as a participant.
Aircraft flight mechanics Straight and level flight of aircraft Aircraft_flight_mechanics > Straight and level flight of aircraft Vertical flight requires no lift. When flying straight upwards the aircraft can reach zero airspeed before falling earthwards; the wing is generating no lift and so does not stall. In straight, climbing flight at constant airspeed, thrust exceeds drag.
Ring of differential operators Summary Ring_of_differential_operators In mathematics, a differential operator is an operator defined as a function of the differentiation operator. It is helpful, as a matter of notation first, to consider differentiation as an abstract operation that accepts a function and returns another function (in the style of a higher-order function in computer science). This article considers mainly linear differential operators, which are the most common type. However, non-linear differential operators also exist, such as the Schwarzian derivative.
Optical extent In refractions and reflections Optical_extent > Conservation of etendue > In refractions and reflections With these definitions, Snell's law of refraction can be written as and its derivative relative to θ multiplied by each other result in where both sides of the equation were also multiplied by dφ which does not change on refraction. This expression can now be written as and multiplying both sides by dS we get that is showing that the etendue of the light refracted at dS is conserved. The same result is also valid for the case of a reflection at a surface dS, in which case nΣ = nS and θΣ = θS.
Wheel and axle Mechanical advantage Wheel_and_axle > Mechanical advantage By varying the radii of the axle and/or wheel, any amount of mechanical advantage may be gained. In this manner, the size of the wheel may be increased to an inconvenient extent.
Adaptive memory History of adaptive memory research Adaptive_memory > History of adaptive memory research Therefore, optimal cognitive performance may be found in problems faced by our ancestors, or related to the environments in which our evolutionary ancestors lived. Based on this finding, Nairne and his colleagues proposed that human memory systems are 'tuned' to information relevant to survival.The first study on the subject of adaptive memory was published in 2007 and its methodology has been replicated many times since. Participants were told to imagine themselves in one of three randomly assigned scenarios.
Constant-recursive sequence Decision problems Constant-recursive_sequence > Behavior > Decision problems The pattern of zeros in a constant-recursive sequence can also be investigated from the perspective of computability theory. To do so, the description of the sequence s n {\displaystyle s_{n}} must be given a finite description; this can be done if the sequence is over the integers or rational numbers, or even over the algebraic numbers. Given such an encoding for sequences s n {\displaystyle s_{n}} , the following problems can be studied: Because the square of a constant-recursive sequence s n 2 {\displaystyle s_{n}^{2}} is still constant-recursive (see closure properties), the existence-of-a-zero problem in the table above reduces to positivity, and infinitely-many-zeros reduces to eventual positivity. Other problems also reduce to those in the above table: for example, whether s n = c {\displaystyle s_{n}=c} for some n {\displaystyle n} reduces to existence-of-a-zero for the sequence s n − c {\displaystyle s_{n}-c} .
Le Sage's theory of gravitation Kinetic theory Le_Sage's_theory_of_gravitation > Kinetic theory Isenkrahe, Ryšánek, du Bois-Reymond Caspar Isenkrahe presented his model in a variety of publications between 1879 and 1915. His basic assumptions were very similar to those of Le Sage and Preston, but he gave a more detailed application of the kinetic theory. However, by asserting that the velocity of the corpuscles after collision was reduced without any corresponding increase in the energy of any other object, his model violated the conservation of energy.
Exponential grow Biology Geometric_growth > Examples > Biology The number of microorganisms in a culture will increase exponentially until an essential nutrient is exhausted, so there is no more of that nutrient for more organisms to grow. Typically the first organism splits into two daughter organisms, who then each split to form four, who split to form eight, and so on. Because exponential growth indicates constant growth rate, it is frequently assumed that exponentially growing cells are at a steady-state.
Evaluation methods Classification of approaches Evaluation_methods > Approaches > Classification of approaches The questions orientation includes approaches that might or might not provide answers specifically related to the value of an object—they call this quasi-evaluation. The values orientation includes approaches primarily intended to determine the value of an object—they call this true evaluation. When the above concepts are considered simultaneously, fifteen evaluation approaches can be identified in terms of epistemology, major perspective (from House), and orientation.
Loop-invariant code motion Invariant code detection Loop-invariant_code_motion > Invariant code detection Usually, a reaching definitions analysis is used to detect whether a statement or expression is loop invariant. For example, if all reaching definitions for the operands of some simple expression are outside of the loop, the expression can be moved out of the loop. Recent work using data-flow dependence analysis allows to detect not only invariant commands but larger code fragments such as an inner loop. The analysis also detects quasi-invariants of arbitrary degrees, that is commands or code fragments that become invariant after a fixed number of iterations of the loop body.
Fish reproduction Parthenogenesis Fish_reproduction > Reproductive strategies > Parthenogenesis A special case of parthenogenesis is gynogenesis. In this type of reproduction, offspring are produced by the same mechanism as in parthenogenesis, however, the egg is stimulated to develop simply by the presence of sperm - the sperm cells do not contribute any genetic material to the offspring. Because gynogenetic species are all female, activation of their eggs requires mating with males of a closely related species for the needed stimulus. The Amazon molly, (pictured), reproduces by gynogenesis.
Oscillation (mathematics) Summary Oscillation_of_a_function_at_a_point In mathematics, the oscillation of a function or a sequence is a number that quantifies how much that sequence or function varies between its extreme values as it approaches infinity or a point. As is the case with limits, there are several definitions that put the intuitive concept into a form suitable for a mathematical treatment: oscillation of a sequence of real numbers, oscillation of a real-valued function at a point, and oscillation of a function on an interval (or open set).
Spectral theorem Hermitian maps and Hermitian matrices Spectral_theorem > Finite-dimensional case > Hermitian maps and Hermitian matrices Now consider the space K = span{e1}⊥, the orthogonal complement of e1. By Hermiticity, K is an invariant subspace of A. Applying the same argument to K shows that A has an eigenvector e2 ∈ K. Finite induction then finishes the proof. The spectral theorem holds also for symmetric maps on finite-dimensional real inner product spaces, but the existence of an eigenvector does not follow immediately from the fundamental theorem of algebra.
Immunosequencing Background Immunosequencing > Background In most areas of biology a single gene codes for one or a few possible proteins. Through V(D)J recombination a number of organisms take a relatively small number of genes coding for antibodies and T-cell receptors (TCRs) and produce a huge diversity of slightly different antibodies and TCRs. The diversity allows for the recognition of a wide array of antigens. As an immune system reacts to infections and other events, the number of different antibodies and TCRs it contains changes. The makeup and quantity of these proteins is sometimes referred to as an immune repertoire. Immunosequencing is a technique utilizing multiplex polymerase chain reaction that allows for the sequencing and quantification of the large diversity of antibody and TCR genes composing an individual's immune repertoire.
Histogram equalization Overview Histogram_equalization > Overview Histogram equalization will work the best when applied to images with much higher color depth than palette size, like continuous data or 16-bit gray-scale images. There are two ways to think about and implement histogram equalization, either as image change or as palette change. The operation can be expressed as P(M(I)) where I is the original image, M is histogram equalization mapping operation and P is a palette.
Local symmetry As a kind of invariance Internal_symmetry > As a kind of invariance Invariance is specified mathematically by transformations that leave some property (e.g. quantity) unchanged. This idea can apply to basic real-world observations. For example, temperature may be homogeneous throughout a room. Since the temperature does not depend on the position of an observer within the room, we say that the temperature is invariant under a shift in an observer's position within the room.
Herwig Schopper Biography Herwig_Schopper > Biography This facility allowed the verification of the standard model of particle physics, namely that it is a renormalizable field theory, leading to the award of the Nobel Prize to the theoreticians Veltman and t'Hooft. Furthermore, it enabled the precise determination of fundamental parameters of the electroweak force, such as the W± and Z masses, and proved the existence of three neutrino families. Thus, this particle accelerator transformed high energy physics into a field of precision measurements and provided estimates to the mass of the top quark, Higgs boson and other supersymmetric and hypothetical particles.
Cambrian substrate revolution Anchorage Cambrian_substrate_revolution > Advantages of burrowing > Anchorage An advantage to living within the substrate would be protection from being washed away by currents.
Indeterminate form Summary Indeterminate_form A limit confirmed to be infinity is not indeterminate since it has been determined to have a specific value (infinity). The term was originally introduced by Cauchy's student Moigno in the middle of the 19th century.
Classical control theory Summary Classical_control_theory The difference between actual and desired output, called the error signal, is applied as feedback to the input of the system, to bring the actual output closer to the reference. Classical control theory deals with linear time-invariant (LTI) single-input single-output (SISO) systems. The Laplace transform of the input and output signal of such systems can be calculated. The transfer function relates the Laplace transform of the input and the output.
Lagrange's theorem (number theory) Summary Lagrange's_theorem_(number_theory) In number theory, Lagrange's theorem is a statement named after Joseph-Louis Lagrange about how frequently a polynomial over the integers may evaluate to a multiple of a fixed prime. More precisely, it states that if p is a prime number, x ∈ Z / p Z {\displaystyle x\in \mathbb {Z} /p\mathbb {Z} } , and f ( x ) ∈ Z {\displaystyle \textstyle f(x)\in \mathbb {Z} } is a polynomial with integer coefficients, then either: every coefficient of f(x) is divisible by p, or f(x) ≡ 0 (mod p) has at most deg f(x) solutionswhere deg f(x) is the degree of f(x). If the modulus is not prime, then it is possible for there to be more than deg f(x) solutions.
Critical line theorem Consequences of the generalized Riemann hypothesis Riemann_Hypothesis > Consequences > Consequences of the generalized Riemann hypothesis In 1934, Chowla showed that the generalized Riemann hypothesis implies that the first prime in the arithmetic progression a mod m is at most Km2log(m)2 for some fixed constant K. In 1967, Hooley showed that the generalized Riemann hypothesis implies Artin's conjecture on primitive roots. In 1973, Weinberger showed that the generalized Riemann hypothesis implies that Euler's list of idoneal numbers is complete. Weinberger (1973) showed that the generalized Riemann hypothesis for the zeta functions of all algebraic number fields implies that any number field with class number 1 is either Euclidean or an imaginary quadratic number field of discriminant −19, −43, −67, or −163.
Reference materials for stable isotope analysis Oxygen Reference_materials_for_stable_isotope_analysis > Isotopic reference materials > Traditional isotope systems > Oxygen Oxygen isotopic ratios are commonly compared to both the VSMOW and the VPDB references. Traditionally oxygen in water is reported relative to VSMOW while oxygen liberated from carbonate rocks or other geologic archives is reported relative to VPDB. As in the case of hydrogen, the oxygen isotopic scale is defined by two materials, VSMOW2 and SLAP2. Measurements of sample δ18O vs. VSMOW can be converted to the VPDB reference frame through the following equation: δ18OVPDB = 0.97001*δ18OVSMOW - 29.99‰ (Brand et al., 2014).
Standard data model Summary Standard_data_model The standardization affects software architecture as solutions that vary from the standard may cause data sharing issues and problems if data is out of compliance with the standard. The more effective standard models have developed in the banking, insurance, pharmaceutical and automotive industries, to reflect the stringent standards applied to customer information gathering, customer privacy, consumer safety, or just in time manufacturing. Typically these use the popular relational model of database management, but some use the hierarchical model, especially those used in manufacturing or mandated by governments, e.g., the DIN codes specified by Germany.
Synthesis phase DNA damage checkpoints Synthesis_phase > DNA damage checkpoints The S-M Checkpoint blocks mitosis until the entire genome has been successfully duplicated. This pathway induces arrest by inhibiting the Cyclin-B-CDK1 complex, which gradually accumulates throughout the cell cycle to promote mitotic entry. The intra-S Phase Checkpoint detects Double Strand Breaks (DSBs) through activation of ATR and ATM kinases.
Glossary of genetics (0–L) D Glossary_of_genetics_(0–L) > D In B-DNA, the most common DNA variant found in nature, the double helix has a right-handed twist with about 10 base pairs per full turn, and the molecular geometry results in an alternating pattern of "grooves" of differing widths (a major groove and a minor groove) between the parallel backbones. double-strand break (DSB) The loss of continuity of the phosphate-sugar backbone in both strands of a double-stranded DNA molecule, in particular when the two breaks occur at sites that are directly across from or very close to each other on the complementary strands. Contrast single-strand break.
Theoretical and experimental justification for the Schrödinger equation Particle state vector Theoretical_and_experimental_justification_for_the_Schrödinger_equation > Schrödinger equation > Particle state vector Rather than polarization states as in the photon case, Schrödinger assumed the state of the vector depended on the position of the particle. If a particle lives in one spatial dimension, then he divided the line up into an infinite number of small bins of length λ {\displaystyle \lambda } and assigned a component of the state vector to each bin The subscript j identifies the bin.
Simulated consciousness Learning Simulated_consciousness > Research and implementation proposals > Aspects of consciousness > Learning Learning is also considered necessary for artificial consciousness. Per Bernard Baars, conscious experience is needed to represent and adapt to novel and significant events. Per Axel Cleeremans and Luis Jiménez, learning is defined as "a set of philogenetically advanced adaptation processes that critically depend on an evolved sensitivity to subjective experience so as to enable agents to afford flexible control over their actions in complex, unpredictable environments".
Metastatic breast cancer Chemotherapy Metastatic_breast_cancer > Treatment > Chemotherapy What receptor hormone the tumour has. Observation of metastases provides direct feedback on the effectiveness of the treatment and often a number of chemotherapy agents are tried sequentially to determine one that works. Adding one or more chemotherapy drugs to an established regimen in women with metastatic breast cancer gives greater tumour shrinkage on imaging but also increased toxicity.Combination chemotherapy is often used in patients with metastatic breast cancer.
Evolutionary approaches to schizophrenia Other studies using evolutionary explanations Evolutionary_approaches_to_schizophrenia > Other studies using evolutionary explanations The biocultural approach is used to try to explain this variance. This model primarily looks at the interaction between genetic heritage and cultural influences and how it impacts the onset of schizophrenia. Studies like this still take into account evolutionary factors but do not accept the schizophrenia enigma.
Intercondylar eminence Summary Intercondylar_eminence The intercondylar area is the separation between the medial and lateral condyle on the upper extremity of the tibia. The anterior and posterior cruciate ligaments and the menisci attach to the intercondylar area.The intercondyloid eminence is composed of the medial and lateral intercondylar tubercles, and divides the intercondylar area into an anterior and a posterior area.
Construction drawing Line styles and types Construction_drawing > Common features > Line styles and types These indicate the cutting plane of an object. 2H pencil Type K lines indicate the alternate positions of an object and the line taken by that object. These are drawn with a long line of 10–20 mm, then a small gap, then a small line of 2 mm, then a gap, then another small line. 2H pencil.
Lambert-Beer law Expression with attenuation coefficient Beer–Lambert_law > Mathematical formulations > Expression with attenuation coefficient The law can be expressed in terms of attenuation coefficient, but in this case is better called the Bouguer-Lambert's law. The (Napierian) attenuation coefficient μ {\displaystyle \mu } and the decadic attenuation coefficient μ 10 = μ ln ⁡ 10 {\displaystyle \mu _{10}={\tfrac {\mu }{\ln 10}}} of a material sample are related to its number densities and amount concentrations asrespectively, by definition of attenuation cross section and molar attenuation coefficient. Then the aw becomesandIn case of uniform attenuation, these relations becomeor equivalently In many cases, the attenuation coefficient does not vary with z {\displaystyle z} , in which case one does not have to perform an integral and can express the law as:where the attenuation is usually an addition of absorption coefficient α {\displaystyle \alpha } (creation of electron-hole pairs) or scattering (for example Rayleigh scattering if the scattering centers are much smaller than the incident wavelength). Also note that for some systems we can put 1 / λ {\displaystyle 1/\lambda } (1 over inelastic mean free path) in place of μ {\displaystyle \mu } .
Federated Search Challenges Federated_Search > Challenges Also, some resources are secure, and should not be arbitrarily queried and exposed in development due to privacy and security concerns. Therefore, the development, testing and performance test environments must include installation and configuration for many sub-systems to allow safe, secure testing. Another challenge within an enterprise is HA/DR (high-availability and disaster recovery).
Stream competency Summary Stream_competency Initiation of motion involves mass, force, friction and stress. Gravity and friction are the two primary forces in play as water flows through a channel. Gravity acts upon water to move it down slope.
Little Boy Summary Little_Boy Fission was accomplished by shooting a hollow cylinder (the "bullet") onto a solid cylinder of the same material (the "target") by means of a charge of nitrocellulose propellant powder. Little Boy contained 64 kilograms (141 lb) of highly enriched uranium, although less than a kilogram underwent nuclear fission. Its components were fabricated at three different plants so that no one would have a copy of the complete design.
Prokaryote Evolution Prokaryotic_cell > Evolution The oldest known fossil eukaryotes are about 1.7 billion years old. However, some genetic evidence suggests eukaryotes appeared as early as 3 billion years ago.While Earth is the only place in the universe where life is known to exist, some have suggested that there is evidence on Mars of fossil or living prokaryotes. However, this possibility remains the subject of considerable debate and skepticism.
Interpretation of probability Logical, epistemic, and inductive probability Interpretation_of_probability > Logical, epistemic, and inductive probability It is widely recognized that the term "probability" is sometimes used in contexts where it has nothing to do with physical randomness. Consider, for example, the claim that the extinction of the dinosaurs was probably caused by a large meteorite hitting the earth. Statements such as "Hypothesis H is probably true" have been interpreted to mean that the (presently available) empirical evidence (E, say) supports H to a high degree. This degree of support of H by E has been called the logical, or epistemic, or inductive probability of H given E. The differences between these interpretations are rather small, and may seem inconsequential.
Smart power Origin Smart_power > Origin Rather, it will find "ways to combine resources into successful strategies in the new context of power diffusion and the 'rise of the rest.'" A successful smart power strategy will provide answers to the following questions: 1) What goals or outcomes are preferred? 2) What resources are available and in which contexts?
Topical steroid withdrawal Cause Topical_steroid_withdrawal > Cause To experience this withdrawal, it generally requires the misuse and/or application of a topical steroid daily for 2 to 4 months, depending on the potency of the topical corticosteroid. In some cases, this has been reported after as little as 2 weeks of use.
Autonomic networking Configuration management Autonomic_networking > Components of autonomic networking > Configuration management Configuration management is responsible for the interaction with network elements and interfaces. It includes an accounting capability with historical perspective that provides for the tracking of configurations over time, with respect to various circumstances. In the biological metaphor, these are the hands and, to some degree, the memory of the autonomic system. On a network, remediation and provisioning are applied via configuration setting of specific devices.
Mir-26 microRNA precursor family Summary Mir-26_microRNA_precursor_family == Origins == The miR-26 microRNA is a small non-coding RNA that is involved in regulating gene expression. The miR-26 family is composed of miR-26a-1, miR-26a-2 and miR-26b located in chromosomes 3, 12 and 2, respectively. Pre-miR-26 with stem-loop structure is processed into mature miR-26 by a series of enzymes of intranuclear and intracytoplasm. The mature miRNA of miR-26a-1 and miR-26a-2 possesses the same sequence, with the exception of 2 different nucleotides in mature miR-26b. miR-26 appears to be a vertebrate specific microRNA and has now been predicted or experimentally validated in many vertebrate species (MIPF0000043).
Oil barrel Related kinds of quantity Barrel_of_oil > Oil barrel > Related kinds of quantity Outside the United States, volumes of oil are usually reported in cubic metres (m3) instead of oil barrels. Cubic metre is the basic volume unit in the International System. In Canada, oil companies measure oil in cubic metres, but convert to barrels on export, since most of Canada's oil production is exported to the US. The nominal conversion factor is 1 cubic metre = 6.2898 oil barrels, but conversion is generally done by custody transfer meters on the border, since the volumes are specified at different temperatures, and the exact conversion factor depends on both density and temperature.
Social rule system theory Textually encoded social rules Social_rule_system_theory > Social rules and the patterning of action > Textually encoded social rules The situations (in which rules are applied or implemented) are particularistic, even idiosyncratic, whereas formal rules of behavior are more or less general. In some situations (especially emergent or new situations), actors may be uncertain or disagree about which rules apply or about the ways in which to apply them. They engage in situational analyses and rule modification, or even rule innovation out of which emerge informal rules (which may be formalized later).
Filter design Typical design requirements Filter_design > Typical design requirements Typical requirements which are considered in the design process are: The filter should have a specific frequency response The filter should have a specific phase shift or group delay The filter should have a specific impulse response The filter should be causal The filter should be stable The filter should be localized (pulse or step inputs should result in finite time outputs) The computational complexity of the filter should be low The filter should be implemented in particular hardware or software
Behavior-based robotics Principles Behavior_based_AI > Principles Behavior-based robotics sets itself apart from traditional artificial intelligence by using biological systems as a model. Classic artificial intelligence typically uses a set of steps to solve problems, it follows a path based on internal representations of events compared to the behavior-based approach. Rather than use preset calculations to tackle a situation, behavior-based robotics relies on adaptability. This advancement has allowed behavior-based robotics to become commonplace in researching and data gathering.Most behavior-based systems are also reactive, which means they need no programming of a chair looks like, or what kind of surface the robot is moving on.
The Entropy Law and the Economic Process Conceptions of scarcity Nicholas_Georgescu-Roegen > Work > Magnum opus on The Entropy Law and the Economic Process > Conceptions of scarcity Hence, mainly two sources of low entropy are available to man, namely the stock of mineral resources in the crust of the earth; and the flow of radiation, received from the sun. Since the sun will continue to shine for billions of years to come, the earth's mineral stock is the scarcer one of these two main sources of low entropy. Whereas the stock of minerals may be extracted from the crust of the earth at a rate of our own choosing (practically), the flow of solar radiation arrives at the surface of the earth at a constant and fixed rate, beyond human control, Georgescu-Roegen maintains.
Gas state Temperature Gaseous_phase > Macroscopic view of gases > Temperature In statistical mechanics, temperature is the measure of the average kinetic energy stored in a molecule (also known as the thermal energy). The methods of storing this energy are dictated by the degrees of freedom of the molecule itself (energy modes). Thermal (kinetic) energy added to a gas or liquid (an endothermic process) produces translational, rotational, and vibrational motion.
Internet search Types of web search engines Internet_search > Technology > Types of web search engines But more important, not every search engine uses the same algorithm to search through the indices. The algorithm is what the search engines use to determine the relevance of the information in the index to what the user is searching for. One of the elements that a search engine algorithm scans for is the frequency and location of keywords on a Web page.
Comparison of DNS server software Features Comparison_of_DNS_server_software > Features Others are divided into smaller programs, each implementing a subsystem of the server. As in the classic Computer Science microkernel debate, the importance and utility of this distinction is hotly debated. The feature matrix in this article does not discuss whether DNS features are provided in a single program or several, so long as those features are provided with the base server package and not with third-party add-on software.
T lymphocytes TCR development summary T-cell_exhaustion > Development > TCR development > TCR development summary β-selection is the first checkpoint, where thymocytes that are able to form a functional pre-TCR (with an invariant alpha chain and a functional beta chain) are allowed to continue development in the thymus. Next, positive selection checks that thymocytes have successfully rearranged their TCRα locus and are capable of recognizing MHC molecules with appropriate affinity. Negative selection in the medulla then eliminates thymocytes that bind too strongly to self-antigens expressed on MHC molecules. These selection processes allow for tolerance of self by the immune system. Typical naive T cells that leave the thymus (via the corticomedullary junction) are self-restricted, self-tolerant, and single positive.
Bone marrow biopsy Test performance Bone_marrow_aspiration > Test performance The skin is cleansed, and a local anesthetic such as lidocaine or procaine is injected to numb the area. Patients may also be pretreated with analgesics and/or anti-anxiety medications, although this is not a routine practice. Typically, the aspirate is performed first.
Technical drawings Computer aided design Technical_drawing > Methods > Computer aided design Both 2D and 3D CAD systems can be used to produce technical drawings for any discipline. The various disciplines (electrical, electronic, pneumatic, hydraulic, etc.) have industry recognized symbols to represent common components. BS and ISO produce standards to show recommended practices but it is up to individuals to produce the drawings to a standard.
Equilibrium chemistry Complexes of metals Equilibrium_chemistry > Complexes of metals A better representation would be + + O2 ⇌ HbO2 + H+as this shows that when hydrogen ion concentration increases the equilibrium is shifted to the left in accordance with Le Châtelier's principle. Hydrogen ion concentration can be increased by the presence of carbon dioxide, which behaves as a weak acid. H2O + CO2 ⇌ HCO−3 + H+The iron atom can also bind to other molecules such as carbon monoxide.
Logic Programming Concurrent logic programming Rule-based_programming > Variants and extensions > Concurrent logic programming These subgoals can also be executed in parallel. Thus concurrent logic programming implements a form of "don't care nondeterminism", rather than "don't know nondeterminism". For example, the following concurrent logic program defines a predicate shuffle(Left, Right, Merge) , which can be used to shuffle two lists Left and Right, combining them into a single list Merge that preserves the ordering of the two lists Left and Right: Here, represents the empty list, and represents a list with first element Head followed by list Tail, as in Prolog.
Glossary of artificial intelligence S Glossary_of_artificial_intelligence > S supervised learning The machine learning task of learning a function that maps an input to an output based on example input-output pairs. It infers a function from labeled training data consisting of a set of training examples. In supervised learning, each example is a pair consisting of an input object (typically a vector) and a desired output value (also called the supervisory signal).
Born–Oppenheimer approximation Derivation Born–Oppenheimer_approximation > Derivation {\displaystyle T_{\text{n}}(\mathbf {R} )_{k'k}\equiv {\big (}\mathbb {H} _{\text{n}}(\mathbf {R} ){\big )}_{k'k}=\delta _{k'k}T_{\text{n}}-\sum _{A,\alpha }{\frac {1}{M_{A}}}\langle \chi _{k'}\|P_{A\alpha }\|\chi _{k}\rangle _{(\mathbf {r} )}P_{A\alpha }+\langle \chi _{k'}\|T_{\text{n}}\|\chi _{k}\rangle _{(\mathbf {r} )}.} The diagonal ( k ′ = k {\displaystyle k'=k} ) matrix elements ⟨ χ k \| P A α \| χ k ⟩ ( r ) {\displaystyle \langle \chi _{k}\|P_{A\alpha }\|\chi _{k}\rangle _{(\mathbf {r} )}} of the operator P A α {\displaystyle P_{A\alpha }} vanish, because we assume time-reversal invariant, so χ k {\displaystyle \chi _{k}} can be chosen to be always real. The off-diagonal matrix elements satisfy ⟨ χ k ′ \| P A α \| χ k ⟩ ( r ) = ⟨ χ k ′ \| \| χ k ⟩ ( r ) E k ( R ) − E k ′ ( R ) .
Modal operator Axiological Modal_operator > Modality interpreted > Axiological Axiological modal operators (G-operators) transform the world's entities into values and disvalues as seen by a social group, a culture, or a historical period. Axiological modalities are highly subjective categories: what is good for one person may be considered as bad by another one.
Fraunhofer diffraction Diffraction by a rectangular aperture Far-field_diffraction_pattern > Examples > Diffraction by a rectangular aperture The form of the diffraction pattern given by a rectangular aperture is shown in the figure on the right (or above, in tablet format). There is a central semi-rectangular peak, with a series of horizontal and vertical fringes. The dimensions of the central band are related to the dimensions of the slit by the same relationship as for a single slit so that the larger dimension in the diffracted image corresponds to the smaller dimension in the slit.
History of compiler construction First compilers History_of_compiler_construction > First compilers Software for early computers was primarily written in assembly language, and before that directly in machine code. It is usually more productive for a programmer to use a high-level language, and programs written in a high-level language can be reused on different kinds of computers. Even so, it took a while for compilers to become established, because they generated code that did not perform as well as hand-written assembler, they were daunting development projects in their own right, and the very limited memory capacity of early computers created many technical problems for practical compiler implementations. The first practical compiler was written by Corrado Böhm in 1951 for his PhD thesis, one of the first computer science doctorates awarded anywhere in the world.
Yang–Mills field History and theoretical description Yang-Mills_field > History and theoretical description The massless gauge bosons of the electroweak SU(2) × U(1) mix after spontaneous symmetry breaking to produce the 3 massive weak bosons (W+, W−, and Z0) as well as the still-massless photon field. The dynamics of the photon field and its interactions with matter are, in turn, governed by the U(1) gauge theory of quantum electrodynamics. The Standard Model combines the strong interaction with the unified electroweak interaction (unifying the weak and electromagnetic interaction) through the symmetry group SU(3) × SU(2) × U(1).
Euchromatin Structure Euchromatin > Structure Euchromatin is composed of repeating subunits known as nucleosomes, reminiscent of an unfolded set of beads on a string, that are approximately 11 nm in diameter. At the core of these nucleosomes are a set of four histone protein pairs: H3, H4, H2A, and H2B. Each core histone protein possesses a 'tail' structure, which can vary in several ways; it is thought that these variations act as "master control switches" through different methylation and acetylation states, which determine the overall arrangement of the chromatin. Approximately 147 base pairs of DNA are wound around the histone octamers, or a little less than 2 turns of the helix. Nucleosomes along the strand are linked together via the histone, H1, and a short space of open linker DNA, ranging from around 0-80 base pairs. The key distinction between the structure of euchromatin and heterochromatin is that the nucleosomes in euchromatin are much more widely spaced, which allows for easier access of different protein complexes to the DNA strand and thus increased gene transcription.
HotSpot (virtual machine) History HotSpot_(virtual_machine) > History In 1997, Sun Microsystems purchased Animorphic.Shortly after acquiring Animorphic, Sun decided to write a new just-in-time (JIT) compiler for the Java virtual machine. This new compiler would give rise to the name HotSpot, derived from the software's behavior: as it runs Java bytecode, as with the Self VM, HotSpot continually analyzes the program's performance for hot spots which are executed often or repeatedly. These are then targeted for optimizing, leading to high-performance execution with a minimum of overhead for less performance-critical code. In one report, the JVM beat some C++ or C code in some benchmarks.Initially available as an add-on for Java 1.2, HotSpot became the default Sun JVM in Java 1.3.
Mass moment of inertia Rigid body Rotational_inertia > Motion in a fixed plane > Rigid body If a mechanical system is constrained to move parallel to a fixed plane, then the rotation of a body in the system occurs around an axis k ^ {\displaystyle \mathbf {\hat {k}} } parallel to this plane. In this case, the moment of inertia of the mass in this system is a scalar known as the polar moment of inertia. The definition of the polar moment of inertia can be obtained by considering momentum, kinetic energy and Newton's laws for the planar movement of a rigid system of particles.If a system of n {\displaystyle n} particles, P i , i = 1 , … , n {\displaystyle P_{i},i=1,\dots ,n} , are assembled into a rigid body, then the momentum of the system can be written in terms of positions relative to a reference point R {\displaystyle \mathbf {R} } , and absolute velocities v i {\displaystyle \mathbf {v} _{i}}: where ω {\displaystyle {\boldsymbol {\omega }}} is the angular velocity of the system and V {\displaystyle \mathbf {V} } is the velocity of R {\displaystyle \mathbf {R} } . For planar movement the angular velocity vector is directed along the unit vector k {\displaystyle \mathbf {k} } which is perpendicular to the plane of movement.
Congruence modulo m Applications Modular_math > Applications The modulo operation, as implemented in many programming languages and calculators, is an application of modular arithmetic that is often used in this context. The logical operator XOR sums 2 bits, modulo 2. In music, arithmetic modulo 12 is used in the consideration of the system of twelve-tone equal temperament, where octave and enharmonic equivalency occurs (that is, pitches in a 1:2 or 2:1 ratio are equivalent, and C-sharp is considered the same as D-flat).
History of the Church–Turing thesis Gandy: "machine computation", discrete, deterministic, and limited to "local causation" by light speed History_of_the_Church–Turing_thesis > Gandy: "machine computation", discrete, deterministic, and limited to "local causation" by light speed ... Both Church and Turing had in mind calculation by an abstract human being using some mechanical aids (such as paper and pencil)"Robert Soare (1995, see below) had issues with this framing, considering Church's paper (1936) published prior to Turing's "Appendix proof" (1937). Gandy attempts to "analyze mechanical processes and so to provide arguments for the following: "Thesis M. What can be calculated by a machine is computable. "Gandy "exclude from consideration devices which are essentially analogue machines ... .The only physical presuppositions made about mechanical devices (Cf Principle IV below) are that there is a lower bound on the linear dimensions of every atomic part of the device and that there is an upper bound (the velocity of light) on the speed of propagation of change".
Radar signal characteristics Unambiguous velocity Radar_signal_characteristics > In the frequency domain > Unambiguous velocity This is an issue only with a particular type of system; the pulse-Doppler radar, which uses the Doppler effect to resolve velocity from the apparent change in frequency caused by targets that have net radial velocities compared to the radar device. Examination of the spectrum generated by a pulsed transmitter, shown above, reveals that each of the sidebands, (both coarse and fine), will be subject to the Doppler effect, another good reason to limit bandwidth and spectral complexity by pulse profiling. Consider the positive shift caused by the closing target in the diagram which has been highly simplified for clarity.
Sau Lan Wu Higgs boson Sau_Lan_Wu > Achievements > Higgs boson On July 4, 2012, following the immense efforts of the ATLAS and CMS Collaborations, CERN announced the discovery of a boson consistent with the predicted characters of Higgs boson with a mass of 125 GeV. This was a statistically significant discovery at the level of 5-sigma, a term meaning that the odds it occurred by chance are less than 1 in 3.5 million. This discovery completes the Standard Model of particle physics which explains most of the phenomena in the visible Universe. Wu is credited as a significant contributor to the discovery with her Wisconsin's group work on the two key decay channels that led to the discovery of the Higgs boson, the decay of the Higgs boson into two gamma-rays (H→ɣɣ), and the decay of the Higgs boson into four leptons (H→ZZ*→4ℓ).
Communication diagram Summary Communication_diagram Reading a communication diagram involves starting at message 1.0, and following the messages from object to object. Communication diagrams show much of the same information as sequence diagrams, but because of how the information is presented, some of it is easier to find in one diagram than the other. Communication diagrams show which elements each one interacts with better, but sequence diagrams show the order in which the interactions take place more clearly.
Radio receiver design Fundamental considerations Radio_receiver_design > Fundamental considerations The objective is to produce a signal-to-noise ratio of the recovered signal sufficient for the intended purpose. This ratio is also often expressed in decibels. A signal-to-noise ratio of 10 dB (signal 10 times as powerful as noise) might be usable for voice communications by experienced operators, but a receiver intended for high-fidelity music reproduction might require 50 dB or higher signal-to-noise ratio.
Continuously Variable Transmission Summary Continuously_Variable_Transmission A continuously variable transmission (CVT) is an automated transmission that can change through a continuous range of gear ratios. This contrasts with other transmissions that provide a limited number of gear ratios in fixed steps. The flexibility of a CVT with suitable control may allow the engine to operate at a constant angular velocity while the vehicle moves at varying speeds. CVTs are used in cars, tractors, side-by-sides, motor scooters, snowmobiles, bicycles, and earthmoving equipment. The most common type of CVT uses two pulleys connected by a belt or chain; however, several other designs have also been used at times.
Multiple signal classification Theory Multiple_signal_classification > Theory The remaining M − p {\displaystyle M-p} eigenvectors correspond to eigenvalue equal to σ 2 {\displaystyle \sigma ^{2}} and span the noise subspace U N {\displaystyle {\mathcal {U}}_{N}} , which is orthogonal to the signal subspace, U S ⊥ U N {\displaystyle {\mathcal {U}}_{S}\perp {\mathcal {U}}_{N}} . Note that for M = p + 1 {\displaystyle M=p+1} , MUSIC is identical to Pisarenko harmonic decomposition. The general idea behind MUSIC method is to use all the eigenvectors that span the noise subspace to improve the performance of the Pisarenko estimator.
Mermin–Wagner theorem Crystals in 2D Mermin–Wagner_theorem > Crystals in 2D The deviations are basically given by the elastic lattice vibrations (acoustic phonons). A direct experimental proof of Mermin–Wagner–Hohenberg fluctuations would be, if the displacements increase logarithmic with the distance of a locally fitted coordinate frame (blue). This logarithmic divergence goes along with an algebraic (slow) decay of positional correlations.
Broadcast satellite Summary Broadcast_satellite A satellite in a geostationary orbit appears stationary, always at the same point in the sky, to ground observers. Popularly or loosely, the term "geosynchronous" may be used to mean geostationary. Specifically, geosynchronous Earth orbit (GEO) may be a synonym for geosynchronous equatorial orbit, or geostationary Earth orbit.
Viscosity models for mixtures Use, definition and dependence Viscosity_models_for_mixtures > Use, definition and dependence Although the pressures changes are big, the fluid phases will flow slowly through the reservoir due to the flow restriction caused by the porous rock. The above definition is based on a shear-driven fluid motion that in its most general form is modelled by a shear stress tensor and a velocity gradient tensor. The fluid dynamics of a shear flow is, however, very well illustrated by the simple Couette flow.
Photoelectrochemistry Summary Photoelectrochemistry Photoelectrochemistry is a subfield of study within physical chemistry concerned with the interaction of light with electrochemical systems. It is an active domain of investigation. One of the pioneers of this field of electrochemistry was the German electrochemist Heinz Gerischer. The interest in this domain is high in the context of development of renewable energy conversion and storage technology.
Apprenticeship learning Inverse reinforcement learning approach Apprenticeship_learning > Mapping function approach > Inverse reinforcement learning approach One domain where AIRP has been used extensively is helicopter control. While simple trajectories can be intuitively derived, complicated tasks like aerobatics for shows has been successful. These include aerobatic maneuvers like - in-place flips, in-place rolls, loops, hurricanes and even auto-rotation landings. This work was developed by Pieter Abbeel, Adam Coates, and Andrew Ng - "Autonomous Helicopter Aerobatics through Apprenticeship Learning"
Natural experiments Summary Natural_experiments Natural experiments are most useful when there has been a clearly defined exposure involving a well defined subpopulation (and the absence of exposure in a similar subpopulation) such that changes in outcomes may be plausibly attributed to the exposure. In this sense, the difference between a natural experiment and a non-experimental observational study is that the former includes a comparison of conditions that pave the way for causal inference, but the latter does not. Natural experiments are employed as study designs when controlled experimentation is extremely difficult to implement or unethical, such as in several research areas addressed by epidemiology (like evaluating the health impact of varying degrees of exposure to ionizing radiation in people living near Hiroshima at the time of the atomic blast) and economics (like estimating the economic return on amount of schooling in US adults).
Biologically inspired engineering Examples Bionics > Examples Neuromorphic chips and silicon retinae have wiring that is modeled after real neural networks. Technoecosystems or 'EcoCyborg' systems involve the coupling of natural ecological processes to technological ones which mimic ecological functions.

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