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Kirchhoff's law (thermodynamics) Summary Kirchhoff's_law_of_thermal_radiation In heat transfer, Kirchhoff's law of thermal radiation refers to wavelength-specific radiative emission and absorption by a material body in thermodynamic equilibrium, including radiative exchange equilibrium. It is a special case of Onsager reciprocal relations as a consequence of the time reversibility of microscopic dynamics, also known as microscopic reversibility. A body at temperature T radiates electromagnetic energy. A perfect black body in thermodynamic equilibrium absorbs all light that strikes it, and radiates energy according to a unique law of radiative emissive power for temperature T (Stefan–Boltzmann law), universal for all perfect black bodies.
Nicolaus Copernicus Copernicus Nicolaus_Copernicus > Copernican system > Copernicus The apparent retrograde and direct motion of the planets arises not from their motion but from the earth's. The motion of the earth alone, therefore, suffices to explain so many apparent inequalities in the heavens. De revolutionibus itself was divided into six sections or parts, called "books": General vision of the heliocentric theory, and a summarized exposition of his idea of the World Mainly theoretical, presents the principles of spherical astronomy and a list of stars (as a basis for the arguments developed in the subsequent books) Mainly dedicated to the apparent motions of the Sun and to related phenomena Description of the Moon and its orbital motions Exposition of the motions in longitude of the non-terrestrial planets Exposition of the motions in latitude of the non-terrestrial planets
Post-concussion syndrome Causes Post-concussion_syndrome > Causes Others believe that post-concussion symptoms are related to common psychological factors. Most common symptoms like headache, dizziness, and sleep problems are similar to those often experienced by individuals diagnosed with depression, anxiety, or post traumatic stress disorder. In many cases, both physiological effects of brain trauma and emotional reactions to these events play a role in the development of symptoms.PCS may be exacerbated by chronic pain. The majority of experts believe that PCS results from a mix of factors, including preexisting psychological factors and those directly relating to the physical injury.
Constructive set theory Arithmetic functions from recursion Intuitionistic_set_theory > Subtheories of ZF > Arithmetic > Arithmetic functions from recursion This then enables a full interpretation of Heyting arithmetic H A {\displaystyle {\mathsf {HA}}} in our set theory, including addition and multiplication functions. With this, N {\displaystyle {\mathbb {N} }} and Z {\displaystyle {\mathbb {Z} }} are well-founded, in the sense of the inductive subsets formulation. Further, arithmetic of rational numbers Q {\displaystyle {\mathbb {Q} }} can then also be defined and its properties, like uniqueness and countability, be proven.
Polychromatic symmetry Summary Polychromatic_symmetry Polychromatic symmetry is a colour symmetry which interchanges three or more colours in a symmetrical pattern. It is a natural extension of dichromatic symmetry. The coloured symmetry groups are derived by adding to the position coordinates (x and y in two dimensions, x, y and z in three dimensions) an extra coordinate, k, which takes three or more possible values (colours).An example of an application of polychromatic symmetry is crystals of substances containing molecules or ions in triplet states, that is with an electronic spin of magnitude 1, should sometimes have structures in which the spins of these groups have projections of + 1, 0 and -1 onto local magnetic fields. If these three cases are present with equal frequency in an orderly array, then the magnetic space group of such a crystal should be three-coloured.
Arithmetic operations Division Arithmetic_operations > Arithmetic operations > Division Division, denoted by the symbols ÷ {\displaystyle \div } or / {\displaystyle /} , is essentially the inverse operation to multiplication. Division finds the quotient of two numbers, the dividend divided by the divisor. Under common rules, dividend divided by zero is undefined. For distinct positive numbers, if the dividend is larger than the divisor, the quotient is greater than 1, otherwise it is less than or equal to 1 (a similar rule applies for negative numbers).
Biracks and biquandles Definitions Biracks_and_biquandles > Definitions {\displaystyle S(a,b_{a})=(b,a^{b}).\,} Then 1. S {\displaystyle S} is a bijection 2. S 1 S 2 S 1 = S 2 S 1 S 2 {\displaystyle S_{1}S_{2}S_{1}=S_{2}S_{1}S_{2}\,} In the second condition, S 1 {\displaystyle S_{1}} and S 2 {\displaystyle S_{2}} are defined by S 1 ( a , b , c ) = ( S ( a , b ) , c ) {\displaystyle S_{1}(a,b,c)=(S(a,b),c)} and S 2 ( a , b , c ) = ( a , S ( b , c ) ) {\displaystyle S_{2}(a,b,c)=(a,S(b,c))} .
Scientific revolution Heliocentrism Scientific_revolution > New ideas > Astronomy > Heliocentrism Kepler was an astronomer who, using the accurate observations of Tycho Brahe, proposed that the planets move around the Sun not in circular orbits but in elliptical ones. Together with his other laws of planetary motion, this allowed him to create a model of the Solar System that was an improvement over Copernicus' original system. Galileo's main contributions to the acceptance of the heliocentric system were his mechanics, the observations he made with his telescope, as well as his detailed presentation of the case for the system.
Radical disproportionation Kinetic isotope effect on disproportionation and recombination Radical_disproportionation > Competition with recombination > Kinetic isotope effect on disproportionation and recombination When the hydrogen atoms in an alkyl radical are displaced with deuterium, disproportionation proceeds at a slightly slower rate whereas the rate of recombination remains the same. Thus disproportionation is weakly affected by the kinetic isotope effect with kH/kD = 1.20 ± 0.15 for ethylene. Hydrogens and deuterons are not involved in recombination reactions. However, deuteron abstraction during disproportionation occurs more slowly than hydrogen abstraction due to the increased mass and reduced vibrational energy of deuterium, although the experimentally observed kH/kD is close to one.
Eudoxus of Cnidus Eudoxan planetary models Eudoxus_of_Cnidus > Astronomy > Eudoxan planetary models A general idea of the content of On Speeds can be gleaned from Aristotle's Metaphysics XII, 8, and a commentary by Simplicius of Cilicia (6th century AD) on De caelo, another work by Aristotle. According to a story reported by Simplicius, Plato posed a question for Greek astronomers: "By the assumption of what uniform and orderly motions can the apparent motions of the planets be accounted for?" Plato proposed that the seemingly chaotic wandering motions of the planets could be explained by combinations of uniform circular motions centered on a spherical Earth, apparently a novel idea in the 4th century BC. In most modern reconstructions of the Eudoxan model, the Moon is assigned three spheres: The outermost rotates westward once in 24 hours, explaining rising and setting.
Embryo drawing Ernst Haeckel (1834–1919) Embryo_drawing > Famous embryo illustrators > Ernst Haeckel (1834–1919) Haeckel portrays a concrete demonstration of his Biogenetic Law through his Gastrea theory, in which he argues that the early cup-shaped gastrula stage of development is a universal feature of multi-celled animals. An ancestral form existed, known as the gastrea, which was a common ancestor to the corresponding gastrula.Haeckel argues that certain features in embryonic development are conserved and palingenetic, while others are caenogenetic. Caenogenesis represents "the blurring of ancestral resemblances in development", which are said to be the result of certain adaptations to embryonic life due to environmental changes.
Johnson thermoelectric energy converter Mechanism of action Johnson_thermoelectric_energy_converter > Mechanism of action Each stage consists of a working fluid chamber that a copper lined membrane electrode assembly (MEA) bisects. A MEA is a proprietary ceramic proton exchange membrane (PEM) that is sandwiched between two electrodes.The operation is similar to an alkali-metal thermal to electric converter, using hydrogen as the working fluid rather than the highly-reactive molten alkali metals, which are difficult to work with. In the high-temperature power stage, expanding high pressure hydrogen from the compression stage converts the heat energy into electrical energy via the MEA.
Ozone destruction Rowland–Molina hypothesis Ozone_depleting > Research history > Rowland–Molina hypothesis Nevertheless, within three years most of the basic assumptions made by Rowland and Molina were confirmed by laboratory measurements and by direct observation in the stratosphere. The concentrations of the source gases (CFCs and related compounds) and the chlorine reservoir species (HCl and ClONO2) were measured throughout the stratosphere, and demonstrated that CFCs were indeed the major source of stratospheric chlorine, and that nearly all of the CFCs emitted would eventually reach the stratosphere. Even more convincing was the measurement, by James G. Anderson and collaborators, of chlorine monoxide (ClO) in the stratosphere.
Euler-Lagrange equation Summary Euler–Lagrange_equation In the calculus of variations and classical mechanics, the Euler–Lagrange equations are a system of second-order ordinary differential equations whose solutions are stationary points of the given action functional. The equations were discovered in the 1750s by Swiss mathematician Leonhard Euler and Italian mathematician Joseph-Louis Lagrange. Because a differentiable functional is stationary at its local extrema, the Euler–Lagrange equation is useful for solving optimization problems in which, given some functional, one seeks the function minimizing or maximizing it. This is analogous to Fermat's theorem in calculus, stating that at any point where a differentiable function attains a local extremum its derivative is zero.
Proportional symbol map Absolute scaling Proportional_symbol_map > Scaling techniques > Absolute scaling This method calculates the exact area of the symbol and resizes it so that its area is mathematically directly proportional to the represented value. For example, if circles are being used to represent GDP on a global map, then a country with a value of 58 would have a circle with twice the area as a country with a value of 29. If circles are being used, the sizes of all symbols are calculated based on a chosen size for any one of the symbols (often, but not necessarily, the minimum value). Say the cartographer decides that a value v0 will have a circle of radius r0. Then for any other value v, the radius r is determined by setting the areas in direct proportion to the values: This can then be solved for r:
Multifactor dimensionality reduction Machine learning with MDR Multifactor_dimensionality_reduction > Machine learning with MDR That is, machine learning algorithms are good at finding patterns in completely random data. It is often difficult to determine whether a reported pattern is an important signal or just chance. One approach is to estimate the generalizability of a model to independent datasets using methods such as cross-validation.
Timestamp-based concurrency control Summary Timestamp-based_concurrency_control In computer science, a timestamp-based concurrency control algorithm is a non-lock concurrency control method. It is used in some databases to safely handle transactions, using timestamps.
Fat comma PHP Fat_comma > Subtleties > PHP In PHP, the fat comma is termed a double arrow, and is used to specify key/value relationships when declaring an array. Unlike in Perl, the double arrow does not treat what comes before it as a bare word, but rather evaluates it. Hence, constants used with the double arrow will be evaluated:
CRISPR/Cas tools Summary CRISPR/Cas_tools CRISPR-Cas design tools are computer software platforms and bioinformatics tools used to facilitate the design of guide RNAs (gRNAs) for use with the CRISPR/Cas gene editing system.
Prion diseases PrPC Prion_diseases > Prion protein > Structure > PrPC The normal protein is not sedimentable; meaning that it cannot be separated by centrifuging techniques. Its function is a complex issue that continues to be investigated. PrPC binds copper (II) ions with high affinity.
Cache associativity Set-associative cache Direct_mapped_cache > Set-associative cache Set-associative cache is a trade-off between direct-mapped cache and fully associative cache. A set-associative cache can be imagined as a n × m matrix. The cache is divided into ‘n’ sets and each set contains ‘m’ cache lines. A memory block is first mapped onto a set and then placed into any cache line of the set.
Geometric sequence Elementary properties Geometrical_progression > Elementary properties This result was taken by T.R. Malthus as the mathematical foundation of his Principle of Population. Note that the two kinds of progression are related: exponentiating each term of an arithmetic progression yields a geometric progression, while taking the logarithm of each term in a geometric progression with a positive common ratio yields an arithmetic progression. An interesting result of the definition of the geometric progression is that any three consecutive terms a, b and c will satisfy the following equation: b 2 = a c {\displaystyle b^{2}=ac} where b is considered to be the geometric mean between a and c.
Epigenetics Repair of oxidative DNA damage can alter epigenetic markers Epigenetic_landscape > Molecular basis > DNA repair > Repair of oxidative DNA damage can alter epigenetic markers Polymerase beta is the main human polymerase in short-patch BER of oxidative DNA damage. Jiang et al. also found that polymerase beta recruited the DNA methyltransferase protein DNMT3b to BER repair sites. They then evaluated the methylation pattern at the single nucleotide level in a small region of DNA including the promoter region and the early transcription region of the BRCA1 gene.
Data network Internet Data_networking > Organizational scope > Internet An internetwork is the connection of multiple different types of computer networks to form a single computer network using higher-layer network protocols and connecting them together using routers. The Internet is the largest example of internetwork. It is a global system of interconnected governmental, academic, corporate, public, and private computer networks. It is based on the networking technologies of the Internet protocol suite.
Hypothesis Testing Criticism Statistical_test > Criticism Confusion resulting (in part) from combining the methods of Fisher and Neyman–Pearson which are conceptually distinct. Emphasis on statistical significance to the exclusion of estimation and confirmation by repeated experiments. Rigidly requiring statistical significance as a criterion for publication, resulting in publication bias.
Competitive examination Types Competitive_examination > Types These tests can use individual's scores to focus on improving the skills that were lacking in comprehension. Performance-based assessments require students to solve real-world problems or produce something with real-world application. For example, the student can demonstrate baking skills by baking a cake, and having the outcome judged for appearance, flavor, and texture.
Enzyme Classification and nomenclature ENZYME_STRUCTURE_AND_FUNCTION > Classification and nomenclature That is, the first number broadly classifies the enzyme based on its mechanism while the other digits add more and more specificity.The top-level classification is: EC 1, Oxidoreductases: catalyze oxidation/reduction reactions EC 2, Transferases: transfer a functional group (e.g. a methyl or phosphate group) EC 3, Hydrolases: catalyze the hydrolysis of various bonds EC 4, Lyases: cleave various bonds by means other than hydrolysis and oxidation EC 5, Isomerases: catalyze isomerization changes within a single molecule EC 6, Ligases: join two molecules with covalent bonds. EC 7, Translocases: catalyze the movement of ions or molecules across membranes, or their separation within membranes.These sections are subdivided by other features such as the substrate, products, and chemical mechanism. An enzyme is fully specified by four numerical designations.
Hydrogenic atom Schrödinger solution Hydrogenic_atom > Schrödinger solution In the solution to the Schrödinger equation, which is non-relativistic, hydrogen-like atomic orbitals are eigenfunctions of the one-electron angular momentum operator L and its z component Lz. A hydrogen-like atomic orbital is uniquely identified by the values of the principal quantum number n, the angular momentum quantum number l, and the magnetic quantum number m. The energy eigenvalues do not depend on l or m, but solely on n. To these must be added the two-valued spin quantum number ms = ±1⁄2, setting the stage for the Aufbau principle. This principle restricts the allowed values of the four quantum numbers in electron configurations of more-electron atoms. In hydrogen-like atoms all degenerate orbitals of fixed n and l, m and s varying between certain values (see below) form an atomic shell.
Pollee Concept Pollee > Concept The idea behind Pollee was to provide for women an easy and convenient urination alternative to portable toilets. The plan was to reduce the queues in front of the portable toilets: "Our drive is that Pollee becomes a real queue-killer that enables girls to get peeing over and done with quickly, so they can get on with the more fun and important things. Queuing is such a waste of life!" — UIWE Together with the designers Sara Nanna and Nuala Collins, three prototypes were developed.
Group conflict Belief domains that contribute Group_conflict > Intergroup conflict > Belief domains that contribute As part of this belief system they also noted a corresponding belief in the inferiority of all other group's heritage, the ability to impose their standards and beliefs on less powerful groups, evidence of the group's core beliefs and values in their practices, programs and policies as well as in the institutions and structures of the group's society, and that they were able to operate outside the level of conscious awareness. Injustice: At the individual level, this belief revolves around perceived mistreatment by others, and/or the world at large. At the group level, this translates to a world view that the ingroup has significant and legitimate grievances against an outgroup.
Object Modeling in Color Summary UML_colors That extra dimension allowed modelers to see important aspects of the models (the pink classes, for instance), and to spot areas that may need reviewing (unusual combinations of color classes linked together). The technique also made it easy to help determine aspects of the domain model – especially for newcomers to modeling. For example, by simply looking first for "pinks" in the domain, it was easy to begin to get some important classes identified for a given domain. It was also easy to review the standard types of attributes, methods, and so on, for applicability to the current domain effort.
Pseudohyperaldosteronism Genetic forms Pseudohyperaldosteronism > Causes > Genetic forms These mutations limit the ability of 11-β-HSD2 to transform active cortisol to the less active cortisone. Excess cortisol is then able to bind and activate mineralocorticoid receptors due to receptor cross-reactivity leading to aldosterone-like effects. Congenital Adrenal Hyperplasia is an autosomal recessive disorder with multiple types, two of which lead to pseudohyperaldosteronism. Deficiency of 11-beta-hydroxylase blocks the conversion of 11-deoxycorticosterone (DOC) to corticosterone leading to an excess of DOC which acts as a mineralocorticoid similar to aldosterone. Deficiency of 17-alpha-hydroxylase blocks the conversion of pregnenolone and progesterone to their 17-a-hydroxy forms leading to increased mineralocorticoid production.
Oxygen partial pressure Summary Dephlogisticated_air However, ozone present at the surface is a byproduct of smog and thus a pollutant. Oxygen was isolated by Michael Sendivogius before 1604, but it is commonly believed that the element was discovered independently by Carl Wilhelm Scheele, in Uppsala, in 1773 or earlier, and Joseph Priestley in Wiltshire, in 1774. Priority is often given for Priestley because his work was published first.
Aggregate demand Summary Aggregate_demand There are many factors that can shift the AD curve. Rightward shifts result from increases in the money supply, in government expenditure, or in autonomous components of investment or consumption spending, or from decreases in taxes. According to the aggregate demand-aggregate supply model, when aggregate demand increases, there is movement up along the aggregate supply curve, giving a higher level of prices.
Suppression capacitor Electronic circuits Power_capacitor > Applications > Electronic circuits Some typical applications of film capacitors for use in electronic equipment Polypropylene film capacitors meet the criteria for stability Class 1 capacitors, and have low electrical losses and nearly linear behavior over a very wide temperature and frequency range. They are used for oscillators and resonant circuits; for electronic filter applications with high quality factor (Q) such as high-pass filters, low-pass filters and band-pass filters as well as for tuning circuits; for audio crossovers in loudspeakers; in sample and hold A/D converters and in peak voltage detectors. Tight capacitance tolerances are required for timing applications in signal lights or pulse width generators to control the speed of motors, PP film capacitors are also well-suited because of their very low leakage current. Class 1 PP film capacitors are able to handle higher current than stability Class 1 ceramic capacitors.
X Protocol Example X_Window_core_protocol > Example The following is a possible example of interaction between a server and a program that creates a window with a black box in it and exits on a keypress. In this example, the server does not send any reply because the client requests do not generate replies. These requests could generate errors. The client opens the connection with the server and sends the initial packet specifying the byte order it is using.
Virtual memory Thrashing Virtual_address_translation > Paged virtual memory > Thrashing In this updated swap-token implementation, a priority counter is set for each process to track the number of swap-out pages. The token is always given to the process with a high priority, which has a high number of swap-out pages. The length of the time stamp is not a constant but is determined by the priority: the higher the number of swap-out pages of a process, the longer the time stamp for it will be.
Glossary of chemistry terms E Glossary_of_chemistry_terms > E electron configuration The distribution of the electrons of an atom or molecule within atomic or molecular orbitals. An extensive system of notation is used to concisely and uniquely display information about the electron configuration of each atomic species. Knowledge of the specific arrangements of electrons in different atoms is useful for understanding chemical bonds and the organization of the periodic table of the elements.
Pulse-width modulation Time proportioning Pulse_width_modulation > Principle > Time proportioning Many digital circuits can generate PWM signals (e.g., many microcontrollers have PWM outputs). They normally use a counter that increments periodically (it is connected directly or indirectly to the clock of the circuit) and is reset at the end of every period of the PWM. When the counter value is more than the reference value, the PWM output changes state from high to low (or low to high). This technique is referred to as time proportioning, particularly as time-proportioning control – which proportion of a fixed cycle time is spent in the high state.
Unisolvence theorem Lebesgue constants Polynomial_interpolation > Lebesgue constants We fix the interpolation nodes x0, ..., xn and an interval containing all the interpolation nodes. The process of interpolation maps the function f to a polynomial p. This defines a mapping X from the space C() of all continuous functions on to itself. The map X is linear and it is a projection on the subspace P ( n ) {\displaystyle P(n)} of polynomials of degree n or less. The Lebesgue constant L is defined as the operator norm of X. One has (a special case of Lebesgue's lemma): In other words, the interpolation polynomial is at most a factor (L + 1) worse than the best possible approximation.
Evolution of eusociality Group selection Evolution_of_eusociality > Mechanisms > Group selection Natural Selection Acts on Emergent Traits: The interactions of the individuals can be considered as part of the extended phenotype of the queen. These interactions produce emergent properties upon which natural selection can act.
List of aqueous ions by element Periodic table notes List_of_aqueous_ions_by_element > Periodic table distribution > Periodic table notes Rather than the periodic table being the sum of its groups and periods an examination of the image shows several patterns Thus, there is a largely a left-to-right transition in metallic character seen in the red-orange-sand-yellow colours for the metals, and the turquoise, blue and violet colours for the nonmetals. The dashed line seen in the periods 1 to 4 corresponds to notions of a dividing line between metals and nonmetals. The mixed species in periods 5 and 6 shows how much trouble chemists can have in assessing where to continue the dividing line. The separate dashed boundary around the Nb-Ta-W-Tc-Re-Os-Ir hexad is an exemplar for the reputation many transition metals have for nonmetallic chemistry.
Hierarchical Bayesian model History Belief_networks > History The term Bayesian network was coined by Judea Pearl in 1985 to emphasize: the often subjective nature of the input information the reliance on Bayes' conditioning as the basis for updating information the distinction between causal and evidential modes of reasoningIn the late 1980s Pearl's Probabilistic Reasoning in Intelligent Systems and Neapolitan's Probabilistic Reasoning in Expert Systems summarized their properties and established them as a field of study.
Symbolic interactionism Premises Symbolic_interactionism > Assumptions, premises, and research methodology > Premises Blumer, following Mead, claimed people interact with each other by interpreting or defining each other's actions instead of merely reacting to each other's actions. Their "response" is not made directly to the actions of one another but instead is based on the meaning which they attach to such actions. Thus, human interaction is mediated by the use of symbols and signification, by interpretation, or by ascertaining the meaning of one another's actions.
Equations of motion Analytical mechanics Equations_of_motion > Analytical mechanics The time derivatives of the generalized coordinates are the generalized velocities The Euler–Lagrange equations are where the Lagrangian is a function of the configuration q and its time rate of change dq/dt (and possibly time t) Setting up the Lagrangian of the system, then substituting into the equations and evaluating the partial derivatives and simplifying, a set of coupled N second order ODEs in the coordinates are obtained. Hamilton's equations are where the Hamiltonian is a function of the configuration q and conjugate "generalized" momenta in which ∂/∂q = (∂/∂q1, ∂/∂q2, …, ∂/∂qN) is a shorthand notation for a vector of partial derivatives with respect to the indicated variables (see for example matrix calculus for this denominator notation), and possibly time t, Setting up the Hamiltonian of the system, then substituting into the equations and evaluating the partial derivatives and simplifying, a set of coupled 2N first order ODEs in the coordinates qi and momenta pi are obtained. The Hamilton–Jacobi equation is where is Hamilton's principal function, also called the classical action is a functional of L. In this case, the momenta are given by Although the equation has a simple general form, for a given Hamiltonian it is actually a single first order non-linear PDE, in N + 1 variables. The action S allows identification of conserved quantities for mechanical systems, even when the mechanical problem itself cannot be solved fully, because any differentiable symmetry of the action of a physical system has a corresponding conservation law, a theorem due to Emmy Noether. All classical equations of motion can be derived from the variational principle known as Hamilton's principle of least action stating the path the system takes through the configuration space is the one with the least action S.
History of the function concept Relational form of a function History_of_the_function_concept > Since 1950 > Relational form of a function The reason for the disappearance of the words "propositional function" e.g., in Suppes (1960), and Halmos (1970), is explained by Tarski (1946) together with further explanation of the terminology: "An expression such as x is an integer, which contains variables and, on replacement of these variables by constants becomes a sentence, is called a SENTENTIAL FUNCTION. But mathematicians, by the way, are not very fond of this expression, because they use the term "function" with a different meaning. ... sentential functions and sentences composed entirely of mathematical symbols (and not words of everyday language), such as: x + y = 5 are usually referred to by mathematicians as FORMULAE. In place of "sentential function" we shall sometimes simply say "sentence" – but only in cases where there is no danger of any misunderstanding".For his part Tarski calls the relational form of function a "FUNCTIONAL RELATION or simply a FUNCTION".
Principles of grid generation Techniques Mesh_generation > Techniques Hybrid techniques do both. A special class of advancing front techniques creates thin boundary layers of elements for fluid flow. In structured mesh generation the entire mesh is a lattice graph, such as a regular grid of squares.
Glossary of engineering: A–L E Glossary_of_engineering:_A–L > E The magnetic field disappears when the current is turned off. The wire turns are often wound around a magnetic core made from a ferromagnetic or ferrimagnetic material such as iron; the magnetic core concentrates the magnetic flux and makes a more powerful magnet. Electromagnetic fieldAn electromagnetic field (also EM field) is a classical (i.e. non-quantum) field produced by accelerating electric charges.
Very long instruction word Motivation Very_long_instruction_word > Motivation A processor that executes every instruction one after the other (i.e., a non-pipelined scalar architecture) may use processor resources inefficiently, yielding potential poor performance. The performance can be improved by executing different substeps of sequential instructions simultaneously (termed pipelining), or even executing multiple instructions entirely simultaneously as in superscalar architectures. Further improvement can be achieved by executing instructions in an order different from that in which they occur in a program, termed out-of-order execution.These three methods all raise hardware complexity. Before executing any operations in parallel, the processor must verify that the instructions have no interdependencies.
Center for Democracy and Technology Privacy and data Center_for_Democracy_and_Technology > Project teams > Privacy and data Additionally, CDT heads the State Privacy Resource Center, which serves as a repository of information to help policymakers at the state and local level craft privacy legislation.AI and Machine Learning The CDTs Privacy and Data team is focusing on how automated processes are making decisions that affect people’s data and privacy because automated programs could make discriminatory decisions that can affect many people’s lives. They are working to ensure that innovation in the field of AI and Machine Learning remains. However, they want to make sure the rights of individuals aren’t taken away and AI is used in a responsible and ethical way.
Stand level modelling Stand description Stand_level_modelling > Stand description group – when there are more than 5 trees, but they are shorter than a harvestable tree. thicket – when there are more than 5 trees, but they are taller than a harvestable tree to around 0.5 ha. rotten group (cluster) – a packed together standing aggregate of trees, trees in the rotten group have different heights and different depths or a stripwise arrangement.
Monatomic hydrogen Isotopes Gaseous_hydrogen > Properties > Isotopes Deuterium is not radioactive, and does not represent a significant toxicity hazard. Water enriched in molecules that include deuterium instead of normal hydrogen is called heavy water. Deuterium and its compounds are used as a non-radioactive label in chemical experiments and in solvents for 1H-NMR spectroscopy.
Suprachiasmatic nucleus Behaviors controlled by the SCN of vertebrates Suprachiasmatic_nucleus > Circadian rhythms of endothermic (warm-blooded) and ectothermic (cold-blooded) vertebrates > Behaviors controlled by the SCN of vertebrates Mice: Among vertebrates, it is known that mammals are endotherms that are capable of homeostatic thermoregulation. It has been shown that mice display thermosensitivity within the SCN. However, the regulation of body temperature in hypothermic mice is more sensitive to the amount of light in their environment.
Schwarzschild vacuum Summary Schwarzschild_vacuum In Einstein's theory of general relativity, the Schwarzschild metric (also known as the Schwarzschild solution) is an exact solution to the Einstein field equations that describes the gravitational field outside a spherical mass, on the assumption that the electric charge of the mass, angular momentum of the mass, and universal cosmological constant are all zero. The solution is a useful approximation for describing slowly rotating astronomical objects such as many stars and planets, including Earth and the Sun. It was found by Karl Schwarzschild in 1916.
Critical resolved shear stress Slip systems and resolved shear stress Critical_resolved_shear_stress > Slip systems and resolved shear stress In the case of two adjacent, randomly oriented grains, one grain will have a larger Schmid factor and thus a smaller yield stress. Under load, this "weaker" grain will yield prior to the "stronger" grain, and as it deforms a stress concentration will build up in the stronger grain near the boundary between them.
Rutherford Aris bibliography Journal articles Rutherford_Aris_bibliography > Journal articles "Studies in optimization–XI: An experimental test of questing controller" (with J.M. Wheeler). Chem.
Common Lisp Data structures Corman_Common_Lisp > Data types > Data structures Usually, only a few types are supported. Many implementations can optimize array functions when the array used is type-specialized.
Quantum Optics History Quantum_Optics > History Light propagating in a restricted volume of space has its energy and momentum quantized according to an integer number of particles known as photons. Quantum optics studies the nature and effects of light as quantized photons. The first major development leading to that understanding was the correct modeling of the blackbody radiation spectrum by Max Planck in 1899 under the hypothesis of light being emitted in discrete units of energy. The photoelectric effect was further evidence of this quantization as explained by Albert Einstein in a 1905 paper, a discovery for which he was to be awarded the Nobel Prize in 1921.
Flow of control Condition-controlled loops Control_structure > Loops > Condition-controlled loops Most programming languages have constructions for repeating a loop until some condition changes. Some variations test the condition at the start of the loop; others test it at the end. If the test is at the start, the body may be skipped completely; if it is at the end, the body is always executed at least once.
Cellular homology Other properties Cellular_homology > Other properties One sees from the cellular chain complex that the n {\displaystyle n} -skeleton determines all lower-dimensional homology modules: H k ( X ) ≅ H k ( X n ) {\displaystyle {H_{k}}(X)\cong {H_{k}}(X_{n})} for k < n {\displaystyle k
Biomolecular Object Network Databank Database structure Biomolecular_Object_Network_Databank > Biomolecular Interaction Network Database (BIND) > Database structure The record may also contain some information on the role of the complex in various interactions and the molecular complex entry links data from 2 or more interaction records. The third component of BIND is the pathway record section. A pathway consists of a network of interactions that are involved in the regulation of cellular processes.
Automated planning Overview Automated_planning > Overview Do actions have a duration? Can several actions be taken concurrently, or is only one action possible at a time? Is the objective of a plan to reach a designated goal state, or to maximize a reward function?
HPG axis Location and regulation Hypothalamic–pituitary–gonadal_axis > Location and regulation Estrogen forms a negative feedback loop by inhibiting the production of GnRH in the hypothalamus. Inhibin acts to inhibit activin, which is a peripherally produced hormone that positively stimulates GnRH-producing cells. Follistatin, which is also produced in all body tissue, inhibits activin and gives the rest of the body more control over the axis.
Cubic harmonic Symmetry and coordinate system Cubic_harmonic > Symmetry and coordinate system In many cases, especially in chemistry and solid-state and condensed-matter physics, the system under investigation doesn't have rotational symmetry. Often it has some kind of lower symmetry, with a special point group representation, or it has no spatial symmetry at all. Biological and biochemical systems, like amino acids and enzymes often belong to low molecular symmetry point groups. The solid crystals of the elements often belong to the space groups and point groups with high symmetry.
Breakthrough Propulsion Physics Program Quantum vacuum energy experiments Breakthrough_Propulsion_Physics_Program > Quantum vacuum energy experiments One topic of investigations was the use of the zero-point energy field. As the Heisenberg uncertainty principle implies that there is no such thing as an exact amount of energy in an exact location, vacuum fluctuations are known to lead to discernible effects such as the Casimir effect. The differential sail is a speculative drive, based on the possibility of inducing differences in the pressure of vacuum fluctuations on either side of a sail-like structure — with the pressure being somehow reduced on the forward surface of the sail, but pushing as normal on the aft surface — and thus propel a vehicle forward.The Casimir effect was investigated experimentally and analytically under the Breakthrough Propulsion Physics project. This included the construction of MicroElectroMechanical (MEM) rectangular Casimir cavities. Theoretical work showed that the effect could be used to create net forces, although the forces would be extremely small. At the conclusion of the project, the Casimir effect was categorized as an avenue for future research.
Pulmonary heart disease Summary Pulmonary_heart_disease Pulmonary heart disease, also known as cor pulmonale, is the enlargement and failure of the right ventricle of the heart as a response to increased vascular resistance (such as from pulmonic stenosis) or high blood pressure in the lungs.Chronic pulmonary heart disease usually results in right ventricular hypertrophy (RVH), whereas acute pulmonary heart disease usually results in dilatation. Hypertrophy is an adaptive response to a long-term increase in pressure. Individual muscle cells grow larger (in thickness) and change to drive the increased contractile force required to move the blood against greater resistance.
Cholestatic hepatitis Primary sclerosing cholangitis Cholestatic_hepatitis > Causes > Rare causes of cholestasis > Primary sclerosing cholangitis Clinical trials are underway for several novel therapies, including obeticholic acid (a bile acid analogue), simtuzumab (a monoclonal antibody), and 24-norursodeoxycholic acid (a synthetic bile acid). Although the pathogenesis of PSC is poorly understood, three dominant theories have been proposed: 1) aberrant immune response, 2) increased intestinal permeability, and 3) dysbiosis of gut microbiota. The first theory involves immune-mediated damage to bile ducts by T cells.
Condensing coil Flow arrangements Condenser_coil > Spiral > Flow arrangements Spiral flow passages are welded at each side for this type of spiral heat exchanger. This type of flow is suitable for handling low density gas, which passes through the cross flow, avoiding pressure loss. It can be used for liquid-liquid applications if one liquid has a considerably greater flow rate than the other.
Dirac mass Making the Schrödinger equation relativistic Dirac_equation > Historical developments and further mathematical details > Making the Schrödinger equation relativistic This has a telling consequence for the interpretation of the equation. Because the equation is second order in the time derivative, one must specify initial values both of the wave function itself and of its first time-derivative in order to solve definite problems.
Boltzmann machine Equilibrium state Boltzmann_machine > Equilibrium state Running the network beginning from a high temperature, its temperature gradually decreases until reaching a thermal equilibrium at a lower temperature. It then may converge to a distribution where the energy level fluctuates around the global minimum.
Hydrogen isotope biogeochemistry Hydrogen isotope formation Hydrogen_isotope_biogeochemistry > Physical chemistry > Hydrogen isotope formation It is important to note that this is classified as a relatively weak beta reaction, so the radioactivity cannot permeate skin. Tritium is thus only hazardous if directly ingested or inhaled. 3 T ⟶ 3 H e + e − + 18.6 M e V {\displaystyle {}^{3}\mathrm {T} \longrightarrow {}^{3}\mathrm {He} +{e}^{-}+18.6\ \mathrm {MeV} }
MicroRNA Turnover Micro_RNA > Turnover However, uridylation may also protect some miRNAs; the consequences of this modification are incompletely understood. Uridylation of some animal miRNAs has been reported. Both plant and animal miRNAs may be altered by addition of adenine (A) residues to the 3' end of the miRNA. An extra A added to the end of mammalian miR-122, a liver-enriched miRNA important in hepatitis C, stabilizes the molecule and plant miRNAs ending with an adenine residue have slower decay rates.
Riemannian connection on a surface Historical overview Riemannian_connection_on_a_surface > Historical overview Cartan's approach was rephrased in the modern language of principal bundles by Ehresmann, after which the subject rapidly took its current form following contributions by Chern, Ambrose and Singer, Kobayashi, Nomizu, Lichnerowicz and others.Connections on a surface can be defined in a variety of ways. The Riemannian connection or Levi-Civita connection is perhaps most easily understood in terms of lifting vector fields, considered as first order differential operators acting on functions on the manifold, to differential operators on sections of the frame bundle. In the case of an embedded surface, this lift is very simply described in terms of orthogonal projection.
Specific entropy History Molar_entropy > History In his 1803 paper Fundamental Principles of Equilibrium and Movement, the French mathematician Lazare Carnot proposed that in any machine, the accelerations and shocks of the moving parts represent losses of moment of activity; in any natural process there exists an inherent tendency towards the dissipation of useful energy. In 1824, building on that work, Lazare's son, Sadi Carnot, published Reflections on the Motive Power of Fire, which posited that in all heat-engines, whenever "caloric" (what is now known as heat) falls through a temperature difference, work or motive power can be produced from the actions of its fall from a hot to cold body. He used an analogy with how water falls in a water wheel.
Refraction index Applications Complex_refractive_index > Applications The refractive index is used to measure solids, liquids, and gases. Most commonly it is used to measure the concentration of a solute in an aqueous solution. It can also be used as a useful tool to differentiate between different types of gemstone, due to the unique chatoyance each individual stone displays. A refractometer is the instrument used to measure the refractive index. For a solution of sugar, the refractive index can be used to determine the sugar content (see Brix).
Musical modes Use Musical_modes > Modern modes > Use The Aeolian forms the base of the most common Western minor scale; in modern practice the Aeolian mode is differentiated from the minor by using only the seven notes of the Aeolian mode. By contrast, minor mode compositions of the common practice period frequently raise the seventh scale degree by a semitone to strengthen the cadences, and in conjunction also raise the sixth scale degree by a semitone to avoid the awkward interval of an augmented second. This is particularly true of vocal music.Traditional folk music provides countless examples of modal melodies.
Biostatistics Use in high-throughput data Biostatistics > Developments and big data > Use in high-throughput data Classical statistical techniques like linear or logistic regression and linear discriminant analysis do not work well for high dimensional data (i.e. when the number of observations n is smaller than the number of features or predictors p: n < p). As a matter of fact, one can get quite high R2-values despite very low predictive power of the statistical model. These classical statistical techniques (esp.
Dual basis Introduction Dual_basis > Introduction To perform operations with a vector, we must have a straightforward method of calculating its components. In a Cartesian frame the necessary operation is the dot product of the vector and the base vector. For example, x = x 1 i 1 + x 2 i 2 + x 3 i 3 {\displaystyle \mathbf {x} =x^{1}\mathbf {i} _{1}+x^{2}\mathbf {i} _{2}+x^{3}\mathbf {i} _{3}} where i k {\displaystyle \mathbf {i} _{k}} is the bases in a Cartesian frame. The components of x {\displaystyle \mathbf {x} } can be found by x k = x ⋅ i k .
Earth radiation Scientific reception Earth_radiation > Scientific reception No solid scientific foundation for these phenomena has been made. A task group of the World Health Organization investigating the effects of extremely low frequency (ELF) electric and magnetic fields on the health of the general public found "no substantive health issues related to ELF electric fields at levels generally encountered by members of the public". The results of techniques used by practitioners of geobiology, such as dowsing or other forms of radiesthesia, have been attributed to the ideomotor phenomenon.
K shortest path routing Algorithm K_shortest_path_routing > Algorithm The Dijkstra algorithm can be generalized to find the k shortest paths.
Predictive Failure Analysis Summary Predictive_Failure_Analysis Predictive Failure Analysis (PFA) refers to methods intended to predict imminent failure of systems or components (software or hardware), and potentially enable mechanisms to avoid or counteract failure issues, or recommend maintenance of systems prior to failure. For example, computer mechanisms that analyze trends in corrected errors to predict future failures of hardware/memory components and proactively enabling mechanisms to avoid them. Predictive Failure Analysis was originally used as term for a proprietary IBM technology for monitoring the likelihood of hard disk drives to fail, although the term is now used generically for a variety of technologies for judging the imminent failure of CPU's, memory and I/O devices. See also first failure data capture.
Magnetic noise Experimental illustrations Magnetic_noise > Experimental illustrations A varying electromagnetic force can be produced either by a moving source of DC magnetic field (e.g. rotating permanent magnet or rotating coil supplied with DC current), or by a steady source of AC magnetic field (e.g. a coil fed by a variable current).
Groundwater hydrology Numerical methods Groundwater_hydrology > Calculation of groundwater flow > Numerical methods The topic of numerical methods is quite large, obviously being of use to most fields of engineering and science in general. Numerical methods have been around much longer than computers have (In the 1920s Richardson developed some of the finite difference schemes still in use today, but they were calculated by hand, using paper and pencil, by human "calculators"), but they have become very important through the availability of fast and cheap personal computers. A quick survey of the main numerical methods used in hydrogeology, and some of the most basic principles are shown below and further discussed in the Groundwater model article. There are two broad categories of numerical methods: gridded or discretized methods and non-gridded or mesh-free methods. In the common finite difference method and finite element method (FEM) the domain is completely gridded ("cut" into a grid or mesh of small elements). The analytic element method (AEM) and the boundary integral equation method (BIEM — sometimes also called BEM, or Boundary Element Method) are only discretized at boundaries or along flow elements (line sinks, area sources, etc.), the majority of the domain is mesh-free.
Vedic Mathematics Originality of methods Vedic_Mathematics > Reception > Originality of methods Dani believes Krishna Tirtha's methods to be a product of his academic training in mathematics and long recorded habit of experimentation with numbers; nonetheless, he considers the work to be an impressive feat. Similar systems include the Trachtenberg system or the techniques mentioned in Lester Meyers's 1947 book High-speed Mathematics. Alex Bellos points out that several of the calculation tricks can also be found in certain European treatises on calculation from the early Modern period.
Science education Pedagogy Biology_education > Pedagogy While the public image of science education may be one of simply learning facts by rote, science education in recent history also generally concentrates on the teaching of science concepts and addressing misconceptions that learners may hold regarding science concepts or other content. Thomas Kuhn, whose 1962 book The Structure of Scientific Revolutions greatly influenced the post-positivist philosophy of science, argued that the traditional method of teaching in the natural sciences tends to produce a rigid mindset.Since the 1980s, science education has been strongly influenced by constructivist thinking. Constructivism in science education has been informed by an extensive research programme into student thinking and learning in science, and in particular exploring how teachers can facilitate conceptual change towards canonical scientific thinking. Constructivism emphasises the active role of the learner, and the significance of current knowledge and understanding in mediating learning, and the importance of teaching that provides an optimal level of guidance to learners.According to a 2004 Policy Forum in Science magazine, "scientific teaching involves active learning strategies to engage students in the process of science and teaching methods that have been systematically tested and shown to reach diverse students.
Pulmonary alveoli Fluid Pulmonary_alveoli > Clinical significance > Diseases > Fluid A pulmonary contusion is a bruise of the lung tissue caused by trauma. Damaged capillaries from a contusion can cause blood and other fluids to accumulate in the tissue of the lung, impairing gas exchange. Pulmonary edema is the buildup of fluid in the parenchyma and alveoli. An edema is usually caused by left ventricular heart failure, or by damage to the lung or its vasculature.
Retrotransposon silencing Heterochromatin formation Retrotransposon_silencing > Small RNA related silencing > Heterochromatin formation EsiRNA and its protein complex may also function to promote the creation of heterochromatin, protein around which DNA is very tightly coiled, near retrotransposon sites, silencing the DNA by making it difficult for transcription related proteins to access it. Likewise, pi-RNA mediated DNA methylation also contributes to the formation of heterochromatin around the methylated site. Methylation and heterochromatin formation allow PIWI and piRNAs to continue to repress retrotransposon even when PIWI's ability to cleave retrotransposons is disrupted (Darricarrere et al 2013).
Concept search Effective searching Concept_search > Effective searching The effectiveness of a concept search can depend on a variety of elements including the dataset being searched and the search engine that is used to process queries and display results. However, most concept search engines work best for certain kinds of queries: Effective queries are composed of enough text to adequately convey the intended concepts. Effective queries may include full sentences, paragraphs, or even entire documents. Queries composed of just a few words are not as likely to return the most relevant results.
Loss of function By impact on protein sequence Sporadic_mutation > Classification of types > By impact on protein sequence A synonymous substitution replaces a codon with another codon that codes for the same amino acid, so that the produced amino acid sequence is not modified. Synonymous mutations occur due to the degenerate nature of the genetic code. If this mutation does not result in any phenotypic effects, then it is called silent, but not all synonymous substitutions are silent.
Joan Robinson's growth model Summary Joan_Robinson's_growth_model There is neutral technical progress. There are only two classes: workers and capitalists, among whom the national income is distributed. Workers save nothing and spend their wage income on consumption.
Gauge boson Massive gauge bosons Gauge_boson > Gauge bosons in the Standard Model > Massive gauge bosons As a result, the universe is permeated by a non-zero Higgs vacuum expectation value (VEV). This VEV couples to three of the electroweak gauge bosons (W+, W− and Z), giving them mass; the remaining gauge boson remains massless (the photon). This theory also predicts the existence of a scalar Higgs boson, which has been observed in experiments at the LHC.
Discovery and development of beta2 agonists Mechanism of long acting β2-agonists Discovery_and_development_of_beta2_agonists > Mechanism of Action > Mechanism of long acting β2-agonists In 1994 Anderson. et al. introduced the plasmalemma diffusion microkinetic theory, explaining what happens to the β2- agonist in the cell membrane lipid bilayer and in the aqueous biophase closest to the binding site of the β2-adrenoceptor. It is postulated that the plasmalemma lipid bilayer of airway smooth muscles acts as a depot for β2-adrenoceptor agonists. β2-adrenoceptor agonists remain available to interact with the β2-adrenoceptor active site after having partitioned into the lipid bilayer.
Immersed boundary method Summary Immersed_boundary_method In computational fluid dynamics, the immersed boundary method originally referred to an approach developed by Charles Peskin in 1972 to simulate fluid-structure (fiber) interactions. Treating the coupling of the structure deformations and the fluid flow poses a number of challenging problems for numerical simulations (the elastic boundary changes the flow of the fluid and the fluid moves the elastic boundary simultaneously). In the immersed boundary method the fluid is represented in an Eulerian coordinate system and the structure is represented in Lagrangian coordinates. For Newtonian fluids governed by the Navier–Stokes equations, the fluid equations are ρ ( ∂ u ( x , t ) ∂ t + u ⋅ ∇ u ) = − ∇ p + μ Δ u ( x , t ) + f ( x , t ) {\displaystyle \rho \left({\frac {\partial {u}({x},t)}{\partial {t}}}+{u}\cdot \nabla {u}\right)=-\nabla p+\mu \,\Delta u(x,t)+f(x,t)} and if the flow is incompressible, we have the further condition that ∇ ⋅ u = 0.
Protein P16 Function P16 > Function This liberates E2F1 from its bound state in the cytoplasm and allows it to enter the nucleus. Once in the nucleus, E2F1 promotes the transcription of target genes that are essential for transition from G1 to S phase.This pathway connects the processes of tumor oncogenesis and senescence, fixing them on opposite ends of a spectrum. On one end, p16 hypermethylation, mutation, or deletion leads to downregulation of the gene and can lead to cancer through the dysregulation of cell cycle progression. Conversely, activation of p16 through reactive oxygen species, DNA damage, or senescence leads to the buildup of p16 in tissues and is implicated in the aging of cells.
Billiards table Tables for other games Billiard_table > Tables for other games Other types of billiard tables are used for specific games, such as Russian pyramid which uses a '12 ft by 6 ft' table (similar to a snooker table but with much smaller pockets), and Asian four ball which uses a pocketless 8 ft by 4 ft table. Games such as bagatelle often had more than six holes, including straight through the bed in the middle of the table, a feature still found in bar billiards and bumper pool.
Diffusion damping Magnitude Diffusion_damping > Magnitude Θ 0 {\displaystyle \Theta _{0}} is the "monopole of the photon distribution function" Ψ {\displaystyle \Psi } is a "gravitational-potential in the Newtonian gauge". The Newtonian gauge is a quantity with importance in the General Theory of Relativity. ( η ) {\displaystyle (\eta )} is the effective temperature.Mathematical calculations of the damping factor depend on k D {\displaystyle {\mathit {k}}_{\mathit {D}}} , or the effective diffusion scale, which in turn depends on a crucial value, the diffusion length, λ D {\displaystyle \lambda _{\mathit {D}}} .
Clay Summary Clay Clay is a very common substance. Shale, formed largely from clay, is the most common sedimentary rock. Although many naturally occurring deposits include both silts and clay, clays are distinguished from other fine-grained soils by differences in size and mineralogy.
Information Object Class (ASN.1) Summary Information_Object_Class_(ASN.1) ASN.1 Information Object Class is a concept widely used in ASN.1 specifications to address issues related to protocol specification similar to issues addressed by CORBA/IDL specifications. Information Object Classes are used for example to specify ROSE (Remote Operations Service Element) protocol in ASN.1.
Freshwater aquarium History Freshwater_aquarium > History This approach was an attempt to mimic a balanced ecosystem in nature. According to this method, fish waste could be consumed by plants, and plants along with the air surface of the water could supply oxygen for the fish.
IBM Db2 Db2 Warehouse on Cloud Db2_for_i > History > Db2 Warehouse on Cloud Elasticity: Db2 Warehouse on Cloud offers independent scaling of storage and compute, so organizations can customize their data warehouses to meet the needs of their businesses. For example, customers can burst on compute during peak demand, and scale down when demand falls. Users can also expand storage capacity as their data volumes grow.

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