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Peptide signal Function (translocation) Cleavable_transit_peptide > Function (translocation) Signal peptides function to prompt a cell to translocate the protein, usually to the cellular membrane. In prokaryotes, signal peptides direct the newly synthesized protein to the SecYEG protein-conducting channel, which is present in the plasma membrane. A homologous system exists in eukaryotes, where the signal peptide directs the newly synthesized protein to the Sec61 channel, which shares structural and sequence homology with SecYEG, but is present in the endoplasmic reticulum. Both the SecYEG and Sec61 channels are commonly referred to as the translocon, and transit through this channel is known as translocation. While secreted proteins are threaded through the channel, transmembrane domains may diffuse across a lateral gate in the translocon to partition into the surrounding membrane.
Linear Independence Definition Linear_dependency > Definition The linear dependency of a sequence of vectors does not depend of the order of the terms in the sequence. This allows defining linear independence for a finite set of vectors: A finite set of vectors is linearly independent if the sequence obtained by ordering them is linearly independent. In other words, one has the following result that is often useful. A sequence of vectors is linearly independent if and only if it does not contain the same vector twice and the set of its vectors is linearly independent.
Major depression disorder Pathophysiology Major_depression_disorder > Pathophysiology Furthermore, a meta-analysis yielded decreased dexamethasone suppression, and increased response to psychological stressors. Further abnormal results have been obscured with the cortisol awakening response, with increased response being associated with depression.Theories unifying neuroimaging findings have been proposed. The first model proposed is the limbic-cortical model, which involves hyperactivity of the ventral paralimbic regions and hypoactivity of frontal regulatory regions in emotional processing. Another model, the cortico-striatal model, suggests that abnormalities of the prefrontal cortex in regulating striatal and subcortical structures result in depression. Another model proposes hyperactivity of salience structures in identifying negative stimuli, and hypoactivity of cortical regulatory structures resulting in a negative emotional bias and depression, consistent with emotional bias studies.
Transfer molding Summary Transfer_moulding This allows thicker reinforcing fiber matrices to be more completely saturated by resin. Furthermore, unlike injection molding the transfer mold casting material may start the process as a solid. This can reduce equipment costs and time dependency. The transfer process may have a slower fill rate than an equivalent injection molding process.
PC Power Supplies Summary Power_supply_rail A power supply unit (PSU) converts mains AC to low-voltage regulated DC power for the internal components of a computer. Modern personal computers universally use switched-mode power supplies. Some power supplies have a manual switch for selecting input voltage, while others automatically adapt to the main voltage.
Nicholas Georgescu-Roegen The production process and the flow-fund model The_Entropy_Law_and_the_Economic_Process > Work > Magnum opus on The Entropy Law and the Economic Process > The production process and the flow-fund model According to the second law of thermodynamics – the entropy law – what happens in the economy is that all matter and energy is transformed from states available for human purposes to states unavailable for human purposes (the degradation principle). This transformation constitutes a unidirectional and irreversible process. Consequently, valuable natural resources ("low entropy") are procured by the input end of the economy; the resources flow through the economy, being transformed and manufactured into goods along the way; and unvaluable waste and pollution ("high entropy") eventually accumulate by the output end.
Centerline (nautical) H Glossary_of_nautical_terms_(A–L) > H Where several headsails are set, a complex arrangement might be termed (from the front and top) flying jib, outer jib, inner jib, and (fore) staysail; less complex would be jib and staysail headstick The spar laced to the head of the topsail. heaveA vessel's transient, vertical, up-and-down motion. heave down To turn a ship on its side (for cleaning), a process which is also known as careening.
Uniform integrability Relation to convergence of random variables Uniformly_integrable > Relation to convergence of random variables A sequence { X n } {\displaystyle \{X_{n}\}} converges to X {\displaystyle X} in the L 1 {\displaystyle L_{1}} norm if and only if it converges in measure to X {\displaystyle X} and it is uniformly integrable. In probability terms, a sequence of random variables converging in probability also converge in the mean if and only if they are uniformly integrable. This is a generalization of Lebesgue's dominated convergence theorem, see Vitali convergence theorem.
DNA databases Genealogical DNA_databases > Types > Genealogical A national or forensic DNA database is not available for non-police purposes. DNA profiles can also be used for genealogical purposes, so that a separate genetic genealogy database needs to be created that stores DNA profiles of genealogical DNA test results. GenBank is a public genetic genealogy database that stores genome sequences submitted by many genetic genealogists.
Origin of photosynthesis Evolutionary record Evolution_of_photosynthesis > Evolution of photosynthetic pathways > Evolutionary record Because C4 metabolism involves a further chemical step, this effect is accentuated. Plant material can be analysed to deduce the ratio of the heavier 13C to 12C. This ratio is denoted δ13C.
Particular values of Riemann zeta function Odd positive integers Particular_values_of_the_Riemann_zeta_function > Positive integers > Odd positive integers There are also results on the irrationality of values of the Riemann zeta function at the elements of certain subsets of the positive odd integers; for example, at least one of ζ(5), ζ(7), ζ(9), or ζ(11) is irrational.The positive odd integers of the zeta function appear in physics, specifically correlation functions of antiferromagnetic XXX spin chain.Most of the identities following below are provided by Simon Plouffe. They are notable in that they converge quite rapidly, giving almost three digits of precision per iteration, and are thus useful for high-precision calculations. Plouffe stated the following identities without proof. Proofs were later given by other authors.
Trickling filter Summary Trickle_filter A trickling filter is a type of wastewater treatment system. It consists of a fixed bed of rocks, coke, gravel, slag, polyurethane foam, sphagnum peat moss, ceramic, or plastic media over which sewage or other wastewater flows downward and causes a layer of microbial slime (biofilm) to grow, covering the bed of media. Aerobic conditions are maintained by splashing, diffusion, and either by forced-air flowing through the bed or natural convection of air if the filter medium is porous.
Proportional compass The added lines Proportional_compass > Galileo's sector > The added lines To see how this works, we start by noting (as can be seen in the figure in circular segment), that the area of the segment is the difference between the area of the pie slice defined by where the chord cuts the circle, and the triangle formed by the chord and the two radii that touch the ends of the chord. The base of the triangle has length 2 c {\displaystyle 2c} , and the height of the triangle is r − h {\displaystyle r-h} , so the area of the triangle is A t = c ( r − h ) {\displaystyle A_{t}=c(r-h)} . Using Pythogras' theorem, we can show that r = ( c 2 + h 2 ) / 2 h {\displaystyle r=(c^{2}+h^{2})/2h} .
Pain receptors Neural Pain_receptors > System overview > Neural Inferior cerebellar peduncle integrates proprioceptive info and outputs to the vestibulocerebellum. The peduncle is not part of the lateral-spinothalamic-tract-pathway; the medulla receives the info and passes it onto the peduncle from elsewhere (see somatosensory system). The thalamus is where pain is thought to be brought into perception; it also aids in pain suppression and modulation, acting like a bouncer, allowing certain intensities through to the cerebrum and rejecting others.
Information processing (psychology) Models and theories Information_processing_(psychology) > In cognitive psychology > Models and theories There are several proposed models or theories that describe the way in which we process information. Every individual has different information overload point with the same information load because individuals have different information-processing capacities (Eppler and Mengis, 2004)
Karp's 21 NP-complete problems Approximations Karp's_21_NP-complete_problems > Approximations As time went on it was discovered that many of the problems can be solved efficiently if restricted to special cases, or can be solved within any fixed percentage of the optimal result. However, David Zuckerman showed in 1996 that every one of these 21 problems has a constrained optimization version that is impossible to approximate within any constant factor unless P = NP, by showing that Karp's approach to reduction generalizes to a specific type of approximability reduction. Note however that these may be different from the standard optimization versions of the problems, which may have approximation algorithms (as in the case of maximum cut).
Lateral meristem Summary Shoot_meristematic Division of meristematic cells provides new cells for expansion and differentiation of tissues and the initiation of new organs, providing the basic structure of the plant body. The cells are small, with small vacuoles or none, and protoplasm filling the cell completely. The plastids (chloroplasts or chromoplasts), are undifferentiated, but are present in rudimentary form (proplastids).
Reaction mixture Elementary reactions Reaction_conditions > Elementary reactions The elementary reaction is the smallest division into which a chemical reaction can be decomposed, it has no intermediate products. Most experimentally observed reactions are built up from many elementary reactions that occur in parallel or sequentially. The actual sequence of the individual elementary reactions is known as reaction mechanism. An elementary reaction involves a few molecules, usually one or two, because of the low probability for several molecules to meet at a certain time.
Permutation tests Literature Permutation_test > Literature New York: Chapman and Hall/CRC ISBN 9780367577711 Good, Phillip I. (2005) Permutation, Parametric and Bootstrap Tests of Hypotheses, 3rd ed., Springer ISBN 0-387-98898-X Good, P (2002). "Extensions of the concept of exchangeability and their applications".
Histone-Modifying Enzymes ADP-ribosylation Histone-Modifying_Enzymes > Uncommon histone modifications > ADP-ribosylation PARP-1 binds histones near the axis where DNA enters and exits the nucleosome and additionally interacts with numerous chromatin-associated proteins which allow for indirect association with chromatin. Upon binding to chromatin, PARP-1 produces repressive histone marks that can alter the conformational state of histones and inhibit gene expression so that DNA repair can take place. Other avenues of transcription regulation by PARP-1 include acting as a transcription coregulator, regulation of RNA and modulation of DNA methylation via inhibiting the DNA methyltransferase Dnmt1.
Devic's disease Anti-AQP4+ variants Neuromyelitis_optica_spectrum_disorder > Pathophysiology > Anti-AQP4+ variants There is a loss of astrocytes, and sometimes also a loss of neurons and oligodendrocytes. Loss of cells other than astrocytes is a consequence of collateral inflammatory damage or astrocyte dysfunction.NMOSD selectively affects the optic nerve, spinal cord, and brain stem. This selectivity can be explained by the increased amount of AQP4 in these structures, and, furthermore, by the increased amount of AQP4 aggregates in the optic nerve and spinal cord.
Extended Kalman Filter Robust extended Kalman filter Extended_Kalman_Filter > Modifications > Robust extended Kalman filter Another way of improving extended Kalman filter performance is to employ the H-infinity results from robust control. Robust filters are obtained by adding a positive definite term to the design Riccati equation. The additional term is parametrized by a scalar which the designer may tweak to achieve a trade-off between mean-square-error and peak error performance criteria.
LOOP (programming language) Summary LOOP_(programming_language) LOOP is a simple register language that precisely captures the primitive recursive functions. The language is derived from the counter-machine model. Like the counter machines the LOOP language comprises a set of one or more unbounded registers, each of which can hold a single non-negative integer.
Generation gap (pattern) Modern languages Generation_gap_(pattern) > Modern languages Modern byte-code language like Java were in their early stages when Vlissides developed his ideas. In a language like Java or C#, this pattern may be followed by generating an interface, which is a completely abstract class. The developer would then hand-modify a concrete implementation of the generated interface. == References ==
Machine learning Physics Machine_learning > History and relationships to other fields > Physics Analytical and computational techniques derived from deep-rooted physics of disordered systems can be extended to large-scale problems, including machine learning, e.g., to analyze the weight space of deep neural networks. Statistical physics is thus finding applications in the area of medical diagnostics.
Ernest Rutherford Model of the atom Ernest_Rutherford > Scientific career > Model of the atom Rutherford continued to make ground breaking discoveries long after receiving the Nobel prize in 1908. Along with Hans Geiger and Ernest Marsden in 1909, he carried out the Geiger–Marsden experiment, which demonstrated the nuclear nature of atoms by deflecting alpha particles passing through a thin gold foil. Rutherford was inspired to ask Geiger and Marsden in this experiment to look for alpha particles with very high deflection angles, of a type not expected from any theory of matter at that time. Such deflections, though rare, were found, and proved to be a smooth but high-order function of the deflection angle. It was Rutherford's interpretation of this data that led him to formulate the Rutherford model of the atom in 1911 – that a very small charged nucleus, containing much of the atom's mass, was orbited by low-mass electrons.In 1912, Rutherford was joined by Niels Bohr (who postulated that electrons moved in specific orbits). Bohr adapted Rutherford's nuclear structure to be consistent with Max Planck's quantum theory, and the resulting Rutherford–Bohr model is considered valid to this day.
Ataxia telangiectasia and Rad3 related Function Ataxia_telangiectasia_and_Rad3_related > Function It is hypothesized that this pathway, which works independently of TOPBP1 pathway, is used to divide labor and possibly respond to differential needs within the cell. It is hypothesized that one pathway may be most active when ATR is carrying out normal support for replicating cells, and the other may be active when the cell is under more extreme replicative stress.It is not just ssDNA that activates ATR, though the existence of RPA associated ssDNA is important. Instead, ATR activation is heavily dependent on the existence of all the proteins previously described, that colocalize around the site of DNA damage.
Rotation (geometry) In Euclidean geometry Rotation_(mathematics) > Definitions and representations > In Euclidean geometry Any rotation about the origin can be represented as the composition of three rotations defined as the motion obtained by changing one of the Euler angles while leaving the other two constant. They constitute a mixed axes of rotation system because angles are measured with respect to a mix of different reference frames, rather than a single frame that is purely external or purely intrinsic. Specifically, the first angle moves the line of nodes around the external axis z, the second rotates around the line of nodes and the third is an intrinsic rotation (a spin) around an axis fixed in the body that moves.
Zermelo–Fraenkel axiomatization History Zermelo-Fraenkel_axioms > History They also independently proposed replacing the axiom schema of specification with the axiom schema of replacement. Appending this schema, as well as the axiom of regularity (first proposed by John von Neumann), to Zermelo set theory yields the theory denoted by ZF. Adding to ZF either the axiom of choice (AC) or a statement that is equivalent to it yields ZFC.
Time arrow Thermodynamic arrow of time Time_arrow > Arrows > Thermodynamic arrow of time However, there are a number of paradoxes regarding violation of the second law of thermodynamics, one of them due to the Poincaré recurrence theorem. This arrow of time seems to be related to all other arrows of time and arguably underlies some of them, with the exception of the weak arrow of time.Harold Blum's 1951 book Time's Arrow and Evolution discusses "the relationship between time's arrow (the second law of thermodynamics) and organic evolution." This influential text explores "irreversibility and direction in evolution and order, negentropy, and evolution." Blum argues that evolution followed specific patterns predetermined by the inorganic nature of the earth and its thermodynamic processes.
Moral Machine Summary Moral_Machine The presented scenarios are often variations of the trolley problem, and the information collected would be used for further research regarding the decisions that machine intelligence must make in the future. For example, as artificial intelligence plays an increasingly significant role in autonomous driving technology, research projects like Moral Machine help to find solutions for challenging life-and-death decisions that will face self-driving vehicles.Moral Machine was active from January 2016 to July 2020. The Moral Machine continues to be available on their website for people to experience.
Semidiameter Special cases Semidiameter > Special cases The semi-diameter of a sphere, circle, or interval is the same thing as its radius — namely, any line segment from the center to its boundary. The semi-diameters of a non-circular ellipse are the halves of its extents along the two axes of symmetry. They are the parameters a, b of the implicit equation ( x a ) 2 + ( y b ) 2 = 1. {\displaystyle \left({\frac {x}{a}}\right)^{2}+\left({\frac {y}{b}}\right)^{2}=1.\,\!}
Invalid science Protocol registration Invalid_science > Reform > Protocol registration Registering research protocols in advance and monitoring them over the course of a study can prevent researchers from modifying the protocol midstream to highlight preferred results. Providing raw data for other researchers to inspect and test can also better hold researchers to account.
Flux qubit Summary Flux_qubit Higher energy eigenstates correspond to much larger (macroscopic) persistent currents, that induce an additional flux quantum to the qubit loop, thus are well separated energetically from the lowest two eigenstates. This separation, known as the "qubit non linearity" criteria, allows operations with the two lowest eigenstates only, effectively creating a two level system. Usually, the two lowest eigenstates will serve as the computational basis for the logical qubit. Computational operations are performed by pulsing the qubit with microwave frequency radiation which has an energy comparable to that of the gap between the energy of the two basis states, similar to RF-SQUID. Properly selected pulse duration and strength can put the qubit into a quantum superposition of the two basis states while subsequent pulses can manipulate the probability weighting that the qubit will be measured in either of the two basis states, thus performing a computational operation.
Compound option Variants Compound_option > Variants Compound options provide their owners with the right to buy or sell another option. These options create positions with greater leverage than do traditional options. There are four basic types of compound options: Call on Call (CoC) Call on Put (CoP) or caput option Put on Put (PoP) Put on Call (PoC)
Ecological niche Segregation versus restriction Ecological_niches > Segregation versus restriction This "mating theory of niche restriction" is supported by the observation that niches of asexual stages are often wider than those of sexually mature stages; that niches become narrower at the time of mating; and that microhabitats of sessile species and of species with small population sizes often are narrower than those of non-sessile species and of species with large population sizes.Niche segregation: The random selection of niches in largely empty niche space will often automatically lead to segregation (this mechanism is of particular importance in the second paradigm). Niches are segregated due to interspecific competition (this mechanism is of particular importance in the first paradigm). Niches of similar species are segregated (as the result of natural selection) in order to prevent interspecific hybridisation, because hybrids are less fit. (Many cases of niche segregation explained by interspecific competition are better explained by this mechanism, i.e., “reinforcement of reproductive barriers”) (e.g., Rohde 2005b).
Equal environments assumption Summary Twin_studies Twins are a valuable source for observation because they allow the study of environmental influence and varying genetic makeup: "identical" or monozygotic (MZ) twins share essentially 100% of their genes, which means that most differences between the twins (such as height, susceptibility to boredom, intelligence, depression, etc.) are due to experiences that one twin has but not the other twin. "Fraternal" or dizygotic (DZ) twins share only about 50% of their genes, the same as any other sibling. Twins also share many aspects of their environment (e.g., uterine environment, parenting style, education, wealth, culture, community) because they are born into the same family.
Cross section (electronics) Preparation Cross_section_(electronics) > Preparation Cross sections can be prepared by several methods typically chosen based on the scale of the feature of interest because the technique affects the smoothness of the final polish. Smoother polishes allow an analysis of smaller features but can also take longer or be more expensive to prepare. Cross sectioning hard materials such as alumina might require a different technique than a soft material like gold or soft plastic.
Constructive quantum field theory Summary Constructive_quantum_field_theory In mathematical physics, constructive quantum field theory is the field devoted to showing that quantum field theory can be defined in terms of precise mathematical structures. This demonstration requires new mathematics, in a sense analogous to classical real analysis, putting calculus on a mathematically rigorous foundation. Weak, strong, and electromagnetic forces of nature are believed to have their natural description in terms of quantum fields.
Weak base Percentage protonated Weak_base > Percentage protonated As seen above, the strength of a base depends primarily on pH. To help describe the strengths of weak bases, it is helpful to know the percentage protonated-the percentage of base molecules that have been protonated. A lower percentage will correspond with a lower pH because both numbers result from the amount of protonation. A weak base is less protonated, leading to a lower pH and a lower percentage protonated.The typical proton transfer equilibrium appears as such: B ( a q ) + H 2 O ( l ) ↔ H B + ( a q ) + O H − ( a q ) {\displaystyle B(aq)+H_{2}O(l)\leftrightarrow HB^{+}(aq)+OH^{-}(aq)} B represents the base. P e r c e n t a g e p r o t o n a t e d = m o l a r i t y o f H B + i n i t i a l m o l a r i t y o f B × 100 % = i n i t i a l × 100 % {\displaystyle Percentage\ protonated={molarity\ of\ HB^{+} \over \ initial\ molarity\ of\ B}\times 100\%={ \over _{initial}}{\times 100\%}} In this formula, initial is the initial molar concentration of the base, assuming that no protonation has occurred.
Post-transcriptional regulation Summary Post-transcriptional_regulation Post-transcriptional regulation is the control of gene expression at the RNA level. It occurs once the RNA polymerase has been attached to the gene's promoter and is synthesizing the nucleotide sequence. Therefore, as the name indicates, it occurs between the transcription phase and the translation phase of gene expression. These controls are critical for the regulation of many genes across human tissues. It also plays a big role in cell physiology, being implicated in pathologies such as cancer and neurodegenerative diseases.
Specific gravities The relative density in soil mechanics Relative_density > Measurement > The relative density in soil mechanics The relative density D R {\displaystyle D_{\mathrm {R} }} a measure of the current void ratio in relation to the maximum and minimum void rations, and applied effective stress control the mechanical behavior of cohesionless soil. Relative density is defined by in which e m a x , e m i n {\displaystyle e_{\mathrm {max} },e_{\mathrm {min} }} , and e {\displaystyle e} are the maximum, minimum and actual void rations.
Global heating Clean energy Man-made_climate_change > Reducing and recapturing emissions > Clean energy Solar panels and onshore wind are now among the cheapest forms of adding new power generation capacity in many locations. Renewables represented 75% of all new electricity generation installed in 2019, nearly all solar and wind. Other forms of clean energy, such as nuclear and hydropower, currently have a larger share of the energy supply.
Heart chambers Heart failure Heart_chambers > Clinical significance > Diseases > Heart failure Heart failure is defined as a condition in which the heart is unable to pump enough blood to meet the demands of the body. Patients with heart failure may experience breathlessness especially when lying flat, as well as ankle swelling, known as peripheral oedema. Heart failure is the result of many diseases affecting the heart, but is most commonly associated with ischemic heart disease, valvular heart disease, or high blood pressure.
Crystallography Summary Crystallography Each point is labelled with its Miller index. The final plot allows the symmetry of the crystal to be established.
Gradient vector field Summary Complete_vector_field Likewise, n coordinates, a vector field on a domain in n-dimensional Euclidean space R n {\displaystyle \mathbb {R} ^{n}} can be represented as a vector-valued function that associates an n-tuple of real numbers to each point of the domain. This representation of a vector field depends on the coordinate system, and there is a well-defined transformation law (covariance and contravariance of vectors) in passing from one coordinate system to the other. Vector fields are often discussed on open subsets of Euclidean space, but also make sense on other subsets such as surfaces, where they associate an arrow tangent to the surface at each point (a tangent vector).
Glossary of engineering: A–L I Glossary_of_engineering:_A–L > I The resulting electrically charged atom or molecule is called an ion. Ionization can result from the loss of an electron after collisions with subatomic particles, collisions with other atoms, molecules and ions, or through the interaction with electromagnetic radiation.
Parkinson's disease Prognosis Parkinson's_disease > Prognosis A disease pattern mainly characterized by tremor as opposed to rigidity, though, predicts an improved survival. Death from aspiration pneumonia is twice as common in individuals with PD as in the healthy population.In 2016, PD resulted in about 211,000 deaths globally, an increase of 161% since 1990. The overall death rate increased by 19% to 1.81 per 100,000 people during that time.
24 (number) In science 24_(number) > In science The atomic number of chromium. The average number of hours in a day (on Earth), also known as a mean solar day. 24! is an approximation (exceeding by just over 3%) of the Avogadro constant.
Gap (chart pattern) Types of gaps Gap_(chart_pattern) > Types of gaps These gaps are associated with a rapid, straight-line advance or decline. A reversal day can easily help to differentiate between the Measuring gap and the Exhaustion gap. When it is formed at the top with heavy volume, there is significant chance that the market is exhausted and prevailing trend is at halt which is ordinarily followed by some other area pattern development.
Receptor downregulation Example: Insulin receptor downregulation Receptor_downregulation > Example: Insulin receptor downregulation Elevated levels of the hormone insulin in the blood trigger downregulation of the associated receptors. When insulin binds to its receptors on the surface of a cell, the hormone receptor complex undergoes endocytosis and is subsequently attacked by intracellular lysosomal enzymes. The internalization of the insulin molecules provides a pathway for degradation of the hormone as well as for regulation of the number of sites that are available for binding on the cell surface. At high plasma concentrations, the number of surface receptors for insulin is gradually reduced by the accelerated rate of receptor internalization and degradation brought about by increased hormonal binding.
Usability Designing for usability Usability > Designing for usability Any system or device designed for use by people should be easy to use, easy to learn, easy to remember (the instructions), and helpful to users. John Gould and Clayton Lewis recommend that designers striving for usability follow these three design principles Early focus on end users and the tasks they need the system/device to do Empirical measurement using quantitative or qualitative measures Iterative design, in which the designers work in a series of stages, improving the design each time
Solar reflectance Insolation effects Astronomical_albedo > Examples of terrestrial albedo effects > Insolation effects The intensity of albedo temperature effects depends on the amount of albedo and the level of local insolation (solar irradiance); high albedo areas in the Arctic and Antarctic regions are cold due to low insolation, whereas areas such as the Sahara Desert, which also have a relatively high albedo, will be hotter due to high insolation. Tropical and sub-tropical rainforest areas have low albedo, and are much hotter than their temperate forest counterparts, which have lower insolation. Because insolation plays such a big role in the heating and cooling effects of albedo, high insolation areas like the tropics will tend to show a more pronounced fluctuation in local temperature when local albedo changes.Arctic regions notably release more heat back into space than what they absorb, effectively cooling the Earth. This has been a concern since arctic ice and snow has been melting at higher rates due to higher temperatures, creating regions in the arctic that are notably darker (being water or ground which is darker color) and reflects less heat back into space. This feedback loop results in a reduced albedo effect.
Quadratic equation History Quadratic_equation > History The writing of the Chinese mathematician Yang Hui (1238–1298 AD) is the first known one in which quadratic equations with negative coefficients of 'x' appear, although he attributes this to the earlier Liu Yi. By 1545 Gerolamo Cardano compiled the works related to the quadratic equations. The quadratic formula covering all cases was first obtained by Simon Stevin in 1594. In 1637 René Descartes published La Géométrie containing the quadratic formula in the form we know today.
Special-purpose programming language In design and implementation Little_language > Overview > In design and implementation Often, these tiny languages can be used together inside a shell to perform more complex programming tasks. The line between domain-specific languages and scripting languages is somewhat blurred, but domain-specific languages often lack low-level functions for filesystem access, interprocess control, and other functions that characterize full-featured programming languages, scripting or otherwise. Many domain-specific languages do not compile to byte-code or executable code, but to various kinds of media objects: GraphViz exports to PostScript, GIF, JPEG, etc., where Csound compiles to audio files, and a ray-tracing domain-specific language like POV compiles to graphics files.
Insect flight Other hypotheses Insect_flight > Evolution and adaptation > Other hypotheses Other hypotheses include Vincent Wigglesworth's 1973 suggestion that wings developed from thoracic protrusions used as radiators.Adrian Thomas and Åke Norberg suggested in 2003 that wings may have evolved initially for sailing on the surface of water as seen in some stoneflies.Stephen P. Yanoviak and colleagues proposed in 2009 that the wing derives from directed aerial gliding descent—a preflight phenomenon found in some apterygota, a wingless sister taxon to the winged insects.
Behavioral endocrinology Hypothalamus Behavioral_endocrinology > The neuroendocrine system > Hypothalamus The hypothalamus is a distinct part of the brain that is made up of neurons and its main purpose is to maintain homeostasis. The hypothalamus also plays an important part in survival of the individual by integrating the interactions between hormonal and behavioral processes, such as, eating behavior and aggressive behavior.
Nicholas Georgescu-Roegen The production process and the flow-fund model The_Entropy_Law_and_the_Economic_Process > Work > Magnum opus on The Entropy Law and the Economic Process > The production process and the flow-fund model From the 1980s, numerous economists have been working on Georgesu-Roegen's flow-fund model. In 1992, Mario Morroni presented a development of the flow-fund model for applied analysis. This model has been implemented in some case studies regarding the textile industry, electronic devices for telecommunication industry, shoe industry, and tie industry.
Weyr canonical form Reduction to the nilpotent case Weyr_canonical_form > Computation of the Weyr canonical form > Reduction to the nilpotent case Let A {\displaystyle A} be a square matrix of order n {\displaystyle n} over an algebraically closed field and let the distinct eigenvalues of A {\displaystyle A} be λ 1 , λ 2 , … , λ k {\displaystyle \lambda _{1},\lambda _{2},\ldots ,\lambda _{k}} . The Jordan–Chevalley decomposition theorem states that A {\displaystyle A} is similar to a block diagonal matrix of the form A = = + = D + N {\displaystyle A={\begin{bmatrix}\lambda _{1}I+N_{1}&&&\\&\lambda _{2}I+N_{2}&&\\&&\ddots &\\&&&\lambda _{k}I+N_{k}\\\end{bmatrix}}={\begin{bmatrix}\lambda _{1}I&&&\\&\lambda _{2}I&&\\&&\ddots &\\&&&\lambda _{k}I\\\end{bmatrix}}+{\begin{bmatrix}N_{1}&&&\\&N_{2}&&\\&&\ddots &\\&&&N_{k}\\\end{bmatrix}}=D+N} where D {\displaystyle D} is a diagonal matrix, N {\displaystyle N} is a nilpotent matrix, and = 0 {\displaystyle =0} , justifying the reduction of N {\displaystyle N} into subblocks N i {\displaystyle N_{i}} . So the problem of reducing A {\displaystyle A} to the Weyr form reduces to the problem of reducing the nilpotent matrices N i {\displaystyle N_{i}} to the Weyr form. This is leads to the generalized eigenspace decomposition theorem.
H4K5ac Epigenetic implications H4K16ac > Epigenetic implications This independence from the DNA sequence enforces the epigenetic nature of histone modifications. Chromatin states are also useful in identifying regulatory elements that have no defined sequence, such as enhancers. This additional level of annotation allows for a deeper understanding of cell specific gene regulation.
Anelasticity Mechanical models Anelasticity > Mechanical models > Mechanical models In the case where only the constants a 0 {\displaystyle a_{0}} and b 0 {\displaystyle b_{0}} are not zero, the body is ideally elastic and is modelled by the Hookean spring. To add internal friction to a model, the Newtonian dashpot is used, represented by a piston moving in an ideally viscous liquid. Its velocity is proportional to the applied force, therefore entirely dissipating work as heat. These two mechanical elements can be combined in series or in parallel.
Stanley sequence Summary Stanley_sequence In mathematics, a Stanley sequence is an integer sequence generated by a greedy algorithm that chooses the sequence members to avoid arithmetic progressions. If S {\displaystyle S} is a finite set of non-negative integers on which no three elements form an arithmetic progression (that is, a Salem–Spencer set), then the Stanley sequence generated from S {\displaystyle S} starts from the elements of S {\displaystyle S} , in sorted order, and then repeatedly chooses each successive element of the sequence to be a number that is larger than the already-chosen numbers and does not form any three-term arithmetic progression with them. These sequences are named after Richard P. Stanley.
Gravimetry Relative gravimeters Satellite_gravimetry > Gravimeters > Relative gravimeters Recently, the SGs, and broadband three axis seismometers operated in gravimeter mode, have begun to detect and characterize the small gravity signals from earthquakes. These signals arrive at the gravimeter at the speed of light, so have the potential to improve earthquake early warning methods. There is some activity to design purpose-built gravimeters of sufficient sensitivity and bandwidth to detect these prompt gravity signals from earthquakes.
Galileo satellites Orbital slots Galileo_satellites > Orbital slots Refer to Galileo Constellation Information for the most up-to-date information.
Ionic strength Importance Ionic_strength > Importance The ionic strength plays a central role in the Debye–Hückel theory that describes the strong deviations from ideality typically encountered in ionic solutions. It is also important for the theory of double layer and related electrokinetic phenomena and electroacoustic phenomena in colloids and other heterogeneous systems. That is, the Debye length, which is the inverse of the Debye parameter (κ), is inversely proportional to the square root of the ionic strength. Both molar and molal ionic strength have been used, often without explicit definition.
Ecological equilibrium Overview Predictive_homeostasis > Overview Where the levels of variables are higher or lower than those needed, they are often prefixed with hyper- and hypo-, respectively such as hyperthermia and hypothermia or hypertension and hypotension. If an entity is homeostatically controlled it does not imply that its value is necessarily absolutely steady in health. Core body temperature is, for instance, regulated by a homeostatic mechanism with temperature sensors in, amongst others, the hypothalamus of the brain.
Series sum Natural numbers Series_sum > Addition of numbers > Natural numbers Taken literally, the above definition is an application of the recursion theorem on the partially ordered set N2. On the other hand, some sources prefer to use a restricted recursion theorem that applies only to the set of natural numbers. One then considers a to be temporarily "fixed", applies recursion on b to define a function "a +", and pastes these unary operations for all a together to form the full binary operation.This recursive formulation of addition was developed by Dedekind as early as 1854, and he would expand upon it in the following decades. He proved the associative and commutative properties, among others, through mathematical induction.
Predictive engineering analytics Model-in-the-Loop Predictive_engineering_analytics > Enabling processes and technologies > Establishing a strong coupling between 1D simulation, 3D simulation and controls engineering > Model-in-the-Loop By combining them with the system models in MiL simulations, potential algorithms can be validated and selected. In practice, MiL involves co-simulation between virtual controls from dedicated controller modeling software and scalable 1D models of the multi-physical system. This provides the right combination of accuracy and calculation speed for investigation of concepts and strategies, as well as controllability assessment.
Spring Constant Summary Force_constant Hooke's law is only a first-order linear approximation to the real response of springs and other elastic bodies to applied forces. It must eventually fail once the forces exceed some limit, since no material can be compressed beyond a certain minimum size, or stretched beyond a maximum size, without some permanent deformation or change of state.
Sequential Monte Carlo methods Applications Particle_filter > Applications Particle filters and Feynman-Kac particle methodologies find application in several contexts, as an effective mean for tackling noisy observations or strong nonlinearities, such as: Bayesian inference, machine learning, risk analysis and rare event sampling Bioinformatics Computational science Economics, financial mathematics and mathematical finance: particle filters can perform simulations which are needed to compute the high-dimensional and/or complex integrals related to problems such as dynamic stochastic general equilibrium models in macro-economics and option pricing Engineering Fault detection and isolation: in observer-based schemas a particle filter can forecast expected sensors output enabling fault isolation Molecular chemistry and computational physics Pharmacokinetics Phylogenetics Robotics, artificial intelligence: Monte Carlo localization is a de facto standard in mobile robot localization Signal and image processing: visual localization, tracking, feature recognition
Corticotropin-releasing factor family Summary Corticotropin-releasing_factor_family The peptides have a variety of physiological effects on stress and anxiety, vasoregulation, thermoregulation, growth and metabolism, metamorphosis and reproduction in various species, and are all released as prohormones.Corticotropin-releasing hormone (CRH) is a releasing hormone found mainly in the paraventricular nucleus of the mammalian hypothalamus that regulates the release of corticotropin (ACTH) from the pituitary gland. The paraventricular nucleus transports CRH to the anterior pituitary, stimulating adrenocorticotropic hormone (ACTH) release via CRH type 1 receptors, thereby activating the hypothalamic-pituitary-adrenal axis (HPA) and, thus, glucocorticoid release. CRH is evolutionary-related to a number of other active peptides.
Turbo machinery Fluid flow Turbomachinery > Turbomachines > Categorization > Fluid flow In the figure: U = Blade velocity, Vf = Flow velocity, V = Absolute velocity, Vr = Relative velocity, Vw = Tangential or Whirl component of velocity.Radial flow turbomachines - When the path of the throughflow is wholly or mainly in a plane perpendicular to the rotation axis, the device is termed a radial flow turbomachine. Therefore, the change of radius between the entry and the exit is finite. A radial turbomachine can be inward or outward flow type depending on the purpose that needs to be served.
Neural circuit Study methods Brain_circuit > Study methods Similarly, simulations of dysfunctional neurotransmitters in neurological conditions (e.g., dopamine in the basal ganglia of Parkinson's patients) can yield insights into the underlying mechanisms for patterns of cognitive deficits observed in the particular patient group. Predictions from these models can be tested in patients or via pharmacological manipulations, and these studies can in turn be used to inform the models, making the process iterative. The modern balance between the connectionist approach and the single-cell approach in neurobiology has been achieved through a lengthy discussion.
Integrated solar combined cycle Boosting efficiency Combined_Cycle_Gas_Turbine > Efficiency > Boosting efficiency Efficiency of the turbine is increased when combustion can run hotter, so the working fluid expands more. Therefore efficiency is limited by whether the first stage of turbine blades can survive higher temperatures. Cooling and materials research are continuing. A common technique, adopted from aircraft, is to pressurise hot-stage turbine blades with coolant.
Scale-space representation Related multi-scale representations Scale-space_representation > Related multi-scale representations A large number of evolution equations have been formulated in this way, motivated by different specific requirements (see the abovementioned book references for further information). It should be noted, however, that not all of these non-linear scale-spaces satisfy similar "nice" theoretical requirements as the linear Gaussian scale-space concept.
Gaseous fission reactor Spacecraft Gaseous_fission_reactor > Spacecraft One might attempt to circumvent the problem by confining the fission fuel magnetically, in a manner similar to the fusion fuel in a tokamak. Unfortunately it is not likely that this arrangement will actually work to contain the fuel, since the ratio of ionization to particle momentum is not favourable. Whereas a tokamak would generally work to contain singly ionized deuterium or tritium with a mass of two or three daltons, the uranium vapour would be at most triply ionized with a mass of 235 dalton (unit).
Christian Doppler Development of the Doppler Effect Christian_Doppler > Biography > Development of the Doppler Effect In 1842, at the age of 38, Doppler gave a lecture to the Royal Bohemian Society of Sciences and subsequently published Über das farbige Licht der Doppelsterne und einiger anderer Gestirne des Himmels ("On the coloured light of the binary stars and some other stars of the heavens"). In this work, Doppler postulated his principle (later named the Doppler effect) that the observed frequency of a wave depends on the relative speed of the source and the observer, and he later tried to use this concept to explain the visible colours of binary stars (this hypothesis was later proven wrong). Doppler also incorrectly believed that if a star were to exceed 136,000 kilometers per second in radial velocity, then it would not be visible to the human eye.
Derivative work Originality requirement Derivative_works > Application of derivative-work copyright > Originality requirement Because the court considered that "it is clear that the originality requirement imposed by the Constitution and the Copyright Act has particular significance in the case of derivative works based on copyrighted preexisting works," it denied relief and dismissed the claim. Thus the law is clear that a derivative work is protectable only to the extent that it embodies original expression. Its non-original aspects are not copyright-protectable (what is loosely called "uncopyrightable").
Ground acceleration Comparison of instrumental and felt intensity Peak_ground_acceleration > Comparison of instrumental and felt intensity Peak ground acceleration provides a measurement of instrumental intensity, that is, ground shaking recorded by seismic instruments. Other intensity scales measure felt intensity, based on eyewitness reports, felt shaking, and observed damage. There is correlation between these scales, but not always absolute agreement since experiences and damage can be affected by many other factors, including the quality of earthquake engineering. Generally speaking, 0.001 g (0.01 m/s2) – perceptible by people 0.02 g (0.2 m/s2) – people lose their balance 0.50 g (5 m/s2) – very high; well-designed buildings can survive if the duration is short.
Ocular lens Summary Ocular_lens By switching the eyepiece, the user can adjust what is viewed. For instance, eyepieces will often be interchanged to increase or decrease the magnification of a telescope. Eyepieces also offer varying fields of view, and differing degrees of eye relief for the person who looks through them.
Barotrauma Pneumothorax Mask_squeeze > Pathophysiology > Pneumothorax A pneumothorax is an abnormal collection of air in the pleural space between the lung and the chest wall. Symptoms typically include sudden onset of sharp, one-sided chest pain and shortness of breath. In a minority of cases, a one-way valve is formed by an area of damaged tissue, and the amount of air in the space between chest wall and lungs increases; this is called a tension pneumothorax. This can cause a steadily worsening oxygen shortage and low blood pressure.
Graph-encoded map Summary Graph-encoded_map However, interpreting a graph-encoded map in this way requires more care. When the same face appears on both sides of an edge, as can happen for instance for a planar embedding of a tree, the two sides give rise to different gem vertices. And when the same vertex appears at both endpoints of a self-loop, the two ends of the edge again give rise to different gem vertices.
Special and general relativity General relativity Theory_of_Relativity > General relativity General relativity is a theory of gravitation developed by Einstein in the years 1907–1915. The development of general relativity began with the equivalence principle, under which the states of accelerated motion and being at rest in a gravitational field (for example, when standing on the surface of the Earth) are physically identical. The upshot of this is that free fall is inertial motion: an object in free fall is falling because that is how objects move when there is no force being exerted on them, instead of this being due to the force of gravity as is the case in classical mechanics. This is incompatible with classical mechanics and special relativity because in those theories inertially moving objects cannot accelerate with respect to each other, but objects in free fall do so.
Normal probability plot Plot types Normal_probability_plot > Plot types This is a sample of size 50 from a normal distribution, plotted as both a histogram, and a normal probability plot. This is a sample of size 50 from a right-skewed distribution, plotted as both a histogram, and a normal probability plot. This is a sample of size 50 from a uniform distribution, plotted as both a histogram, and a normal probability plot.
Social Choice and Individual Values Conditions and theorem Social_Choice_and_Individual_Values > Conditions and theorem A constitution might seem to be a promising alternative to dictatorship and vote-immune social convention or external control. Arrow describes the connectedness of a social ordering as requiring only that some social choice be made from any environment of available social states. Since some social state will prevail, this is hard to deny (especially with no place on the ballot for abstention). The transitivity of a social ordering has an advantage over requiring unanimity (or much less) to change between social states if there is a maladapted status quo (that is, one subject to "democratic paralysis").
MO theory Overview MO_theory > Overview Thus, overall, bonding is far more delocalized in MO theory, which makes it more applicable to resonant molecules that have equivalent non-integer bond orders than valence bond theory. This makes MO theory more useful for the description of extended systems. Robert S. Mulliken, who actively participated in the advent of molecular orbital theory, considers each molecule to be a self-sufficient unit.
Human population Fluctuation Human_population > Fluctuation By 2000, there were approximately ten times as many people on Earth as there had been in 1700. However, this rapid growth did not last. During the period 2000–2005, the United Nations estimates that the world's population was growing at an annual rate of 1.3% (equivalent to around 80 million people), down from a peak of 2.1% during the period 1965–1970.
Supramolecular assemblies Templating reactions Supramolecular_assembly > Templating reactions As studied in coordination chemistry, metal ions (usually transition metal ions) exist in solution bound to ligands, In many cases, the coordination sphere defines geometries conducive to reactions either between ligands or involving ligands and other external reagents. A well known metal-ion-templating was described by Charles Pedersen in his synthesis of various crown ethers using metal cations as template. For example, 18-crown-6 strongly coordinates potassium ion thus can be prepared through the Williamson ether synthesis using potassium ion as the template metal. Metal ions are frequently used for assembly of large supramolecular structures.
Mean density of the Earth Magnetic field Mean_density_of_the_Earth > Geophysical characteristics > Magnetic field The convection movements in the core are chaotic; the magnetic poles drift and periodically change alignment. This causes secular variation of the main field and field reversals at irregular intervals averaging a few times every million years. The most recent reversal occurred approximately 700,000 years ago.The extent of Earth's magnetic field in space defines the magnetosphere.
Probability Interpretations Probability > Interpretations The product of the prior and the likelihood, when normalized, results in a posterior probability distribution that incorporates all the information known to date. By Aumann's agreement theorem, Bayesian agents whose prior beliefs are similar will end up with similar posterior beliefs. However, sufficiently different priors can lead to different conclusions, regardless of how much information the agents share.
List of textbooks on classical mechanics and quantum mechanics Classical mechanics List_of_textbooks_on_classical_mechanics_and_quantum_mechanics > Undergraduate > Classical mechanics Classical Mechanics. Imperial College Press. ISBN 1860944248.
Critical line theorem Lee–Yang theorem Riemann_Hypothesis > Attempted proofs > Lee–Yang theorem The Lee–Yang theorem states that the zeros of certain partition functions in statistical mechanics all lie on a "critical line" with their real part equals to 0, and this has led to some speculation about a relationship with the Riemann hypothesis.
Viscous vortex domains method Discrete formulas Viscous_vortex_domains_method > Discrete formulas Fluid velocity V in point r can be calculated with help of Biot-savart law V ( r ) = 1 2 π ∑ i γ i ⋅ {\displaystyle \mathbf {V} (\mathbf {r} )={\dfrac {1}{2\pi }}\sum _{i}\gamma _{i}\cdot \left} where i indexes domains in flow, ri — tracking point of domain and γi — his circulation. δ is a so-called "radius of discreteness" — small value that smooths the vortex and helps to get rid of singularity in the domain tracking point. It equals to mean distance between domains.
Human memory Working memory Human_memory > Long-term memory > Working memory the phonological loop also has a limit to how much it can hold at once which means that it is easier to remember a lot of short words rather than a lot of long words, according to the word length effect. The visuospatial sketchpad stores visual and spatial information. It is engaged when performing spatial tasks (such as judging distances) or visual ones (such as counting the windows on a house or imagining images).
Primitive recursive arithmetic Summary Primitive_recursive_arithmetic Primitive recursive arithmetic (PRA) is a quantifier-free formalization of the natural numbers. It was first proposed by Norwegian mathematician Skolem (1923), as a formalization of his finitistic conception of the foundations of arithmetic, and it is widely agreed that all reasoning of PRA is finitistic. Many also believe that all of finitism is captured by PRA, but others believe finitism can be extended to forms of recursion beyond primitive recursion, up to ε0, which is the proof-theoretic ordinal of Peano arithmetic. PRA's proof theoretic ordinal is ωω, where ω is the smallest transfinite ordinal.
Telomerase RNA Clinical Significance Vertebrate_telomerase_RNA > Clinical Significance Loss of function mutations in the TERC genomic locus have been associated with a variety of degenerative diseases. Mutations in TERC have been associated with dyskeratosis congenita, idiopathic pulmonary fibrosis, aplastic anemia, and myelodysplasia. Overexpression and improper regulation of TERC have been associated with a variety of cancers. Upregulation of hTR is widely observed in patients with precancerous cervical phenotype as a result of HPV infection.
Extreme response spectrum Summary Extreme_response_spectrum The Extreme Response Spectrum (ERS) (or Maximum Response Spectrum (MRS)) is defined as a curve giving the value of the highest peak of the response of a linear Single Degree of Freedom System (SDOF system) to vibration, according to its natural frequency, for a given damping ratio. The response is described here by the relative movement of the mass of this system in relation to its support. The x-axis refers to the natural frequency and the y-axis to the highest peak multiplied by the square of the quantity (2 π x natural frequency), by analogy with the relative displacement shock response spectrum. The severity of a vibration can be evaluated by calculating the stresses on a mathematical or finite element model of the structure and, for example, comparison with the ultimate stress of the material.
Ever Normal Granary Side effects Ever_Normal_Granary > Side effects The primary action of buffer stocks, creating price stability, is often combined with other mechanisms to meet other goals such as the promotion of domestic industry. That is achieved by setting a minimum price for a certain product above the equilibrium price, the point at which the supply and demand curves cross, which guarantees a minimum price to producers, encouraging them to produce more, thus creating a surplus ready to be used as a buffer stock. The price stability itself may also tempt firms into the market, further boosting supply. The upside is security of supply (such as food security); the downside is huge stockpiles, or in other cases, destruction of commodities. The scheme also makes domestic food more expensive for other countries to purchase and operation of such a scheme can be costly to the operator.Their main advantage, when compared to other forms of government intervention in markets, is that they are a mechanism that achieves its objectives "quickly and directly".
Doughnut chart Ring chart, sunburst chart, and multilevel pie chart Pie_graph > Variants and similar charts > Ring chart, sunburst chart, and multilevel pie chart A ring chart, also known as a sunburst chart or a multilevel pie chart, is used to visualize hierarchical data, depicted by concentric circles. The circle in the center represents the root node, with the hierarchy moving outward from the center. A segment of the inner circle bears a hierarchical relationship to those segments of the outer circle which lie within the angular sweep of the parent segment.
Banach Spaces Banach's theorems Banach_norm > General theory > Banach's theorems Here are the main general results about Banach spaces that go back to the time of Banach's book (Banach (1932)) and are related to the Baire category theorem. According to this theorem, a complete metric space (such as a Banach space, a Fréchet space or an F-space) cannot be equal to a union of countably many closed subsets with empty interiors. Therefore, a Banach space cannot be the union of countably many closed subspaces, unless it is already equal to one of them; a Banach space with a countable Hamel basis is finite-dimensional.

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