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Metabolic Theory of Ecology Theoretical background Metabolic_Theory_of_Ecology > Theoretical background Metabolic rate scales with the mass of an organism of a given species according to Kleiber's law where B is whole organism metabolic rate (in watts or other unit of power), M is organism mass (in kg), and Bo is a mass-independent normalization constant (given in a unit of power divided by a unit of mass. In this case, watts per kilogram): B = B o M 3 / 4 {\displaystyle B=B_{o}M^{3/4}\,} At increased temperatures, chemical reactions proceed faster. This relationship is described by the Boltzmann factor, where E is activation energy in electronvolts or joules, T is absolute temperature in kelvins, and k is the Boltzmann constant in eV/K or J/K: e − E k T {\displaystyle e^{-{\frac {E}{k\,T}}}} While Bo in the previous equation is mass-independent, it is not explicitly independent of temperature. |
Object Data Management Group Major components of the ODMG 3.0 specification Object_Data_Management_Group > Major components of the ODMG 3.0 specification The ODMG Object Definition Language (ODL) was used to define the object types that conform to the ODMG Object Model. The ODMG Object Interchange Format (OIF) was used to dump and load the current state to or from a file or set of files. Object Query Language (OQL). |
Dynamic arrest Silica, SiO2 Glass_transition_temperature > In specific materials > Silica, SiO2 Alternatively, P, which has a valency of 5, helps to reinforce an ordered lattice, and thus increases the Tg.Tg is directly proportional to bond strength, e.g. it depends on quasi-equilibrium thermodynamic parameters of the bonds e.g. on the enthalpy Hd and entropy Sd of configurons – broken bonds: Tg = Hd / where R is the gas constant and fc is the percolation threshold. For strong melts such as SiO2 the percolation threshold in the above equation is the universal Scher–Zallen critical density in the 3-D space e.g. fc = 0.15, however for fragile materials the percolation thresholds are material-dependent and fc ≪ 1. The enthalpy Hd and the entropy Sd of configurons – broken bonds can be found from available experimental data on viscosity. |
Precision matrix Usage Precision_matrix > Usage This means that precision matrices tend to be sparse when many of the dimensions are conditionally independent, which can lead to computational efficiencies when working with them. It also means that precision matrices are closely related to the idea of partial correlation. The precision matrix plays a central role in generalized least squares, compared to ordinary least squares, where P {\displaystyle P} is the identity matrix, and to weighted least squares, where P {\displaystyle P} is diagonal (the weight matrix). |
Minisatellite Mutability Minisatellite > Mutability In alternative models, it is the presence of neighbouring double-strand hotspots which is the primary cause of minisatellite repeat copy number variations. Somatic changes are suggested to result from replication difficulties (which might include replication slippage, among other phenomena).Studies have shown that the evolutionary fate of minisatellites tends towards an equilibrium distribution in the size of alleles, until mutations in the flanking DNA affect the recombinational activity of a minisatellite by suppressing DNA instability. Such an event would ultimately lead to the extinction of a hypermutable minisatellite by meiotic drive. |
Alternation of generations A complex life cycle Alternation_of_generation > Alternation of generations in plants > A complex life cycle Megaspores develop within the megasporangium; typically one of the four spores produced by meiosis gains bulk at the expense of the remaining three, which disappear. 'Female' willow trees (megasporophytes) produce flowers with only carpels (modified leaves that bear the megasporangia). Megaspores germinate producing megagametophytes; at maturity one or more archegonia are produced. |
Statistically close Summary Probability_metric In statistics, probability theory, and information theory, a statistical distance quantifies the distance between two statistical objects, which can be two random variables, or two probability distributions or samples, or the distance can be between an individual sample point and a population or a wider sample of points. A distance between populations can be interpreted as measuring the distance between two probability distributions and hence they are essentially measures of distances between probability measures. Where statistical distance measures relate to the differences between random variables, these may have statistical dependence, and hence these distances are not directly related to measures of distances between probability measures. |
Carl Gustav Jacob Jacobi Scientific contributions Carl_Gustav_Jacob_Jacobi > Scientific contributions He was also one of the early founders of the theory of determinants. In particular, he invented the Jacobian determinant formed from the n2 partial derivatives of n given functions of n independent variables, which plays an important part in changes of variables in multiple integrals, and in many analytical investigations. In 1841 he reintroduced the partial derivative ∂ notation of Legendre, which was to become standard. |
Bacterial morphological plasticity Bimodal effect Bacterial_morphological_plasticity > Environmental cues > Bimodal effect As a result of this, the predator cannot handle more prey until the previous ingested material is consumed or expelled. Moreover, bacterial cell surface charge and hydrophobicity have also been suggested that might reduce grazing ability. Another strategy that bacteria can use for avoiding the predation is to poison their predator. For example, certain bacteria such as Chromobacterium violaceum and Pseudomonas aeruginosa can secrete toxin agents related to quorum sensing to kill their predators. |
60 (number) In mathematics 60_(number) > In mathematics 60 is a highly composite number. Because it is the sum of its unitary divisors (excluding itself), it is a unitary perfect number, and it is an abundant number with an abundance of 48. Being ten times a perfect number, it is a semiperfect number. 60 is a Twin-prime sum of the fifth pair of twin-primes, 29 + 31. |
A New Kind of Science Computation and its implications A_New_Kind_of_Science > Contents > Computation and its implications The thesis of A New Kind of Science (NKS) is twofold: that the nature of computation must be explored experimentally, and that the results of these experiments have great relevance to understanding the physical world. |
Decomposition of spectrum (functional analysis) Self-adjoint operators on Hilbert space Decomposition_of_spectrum_(functional_analysis) > Self-adjoint operators on Hilbert space Hilbert spaces are Banach spaces, so the above discussion applies to bounded operators on Hilbert spaces as well. A subtle point concerns the spectrum of T*. For a Banach space, T* denotes the transpose and σ(T*) = σ(T). For a Hilbert space, T* normally denotes the adjoint of an operator T ∈ B(H), not the transpose, and σ(T*) is not σ(T) but rather its image under complex conjugation. For a self-adjoint T ∈ B(H), the Borel functional calculus gives additional ways to break up the spectrum naturally. |
Optometer (ophthalmic instrument) The modern phoropter or refractor Optometer_(ophthalmic_instrument) > The modern phoropter or refractor Around 1910, binocularity was tested using trial frames which sat on the patient's face or on a support bar, with extra testing devices added to the front of the frames, such as Maddox rods, rotating prisms, and phorometers. The refraction part of the exam was done with trial lenses that fit into the back of the same trial frame. Optometer was the generic name for devices, crude and simple, with rotating batteries of sphere and cylinder lenses placed in front of each eye, one at a time; so there was no testing for binocularity. |
Cooper pairing Description Cooper_pair > Description The BCS theory is also applicable to other fermion systems, such as helium-3. Indeed, Cooper pairing is responsible for the superfluidity of helium-3 at low temperatures. In 2008 it was proposed that pairs of bosons in an optical lattice may be similar to Cooper pairs. |
Back annotation Backannotation Back_annotation > Hierarchy > Backannotation Backannotation is data that could be added to a hierarchical netlist. Usually they are kept separate from the netlist, because several such alternate sets of data could be applied to a single netlist. These data may have been extracted from a physical design, and might provide extra information for more accurate simulations. Usually the data are composed of a hierarchical path and a piece of data for that primitive or finding the values of RC delay due to interconnection. |
Endometrial transformation dose Summary Endometrial_transformation_dose However, decidualization-like reactions have also been observed in some species that don't display hemochorial placentation.In humans, decidualization occurs after ovulation during the menstrual cycle. After implantation of the embryo, the decidua further develops to mediate the process of placentation. In the event no embryo is implanted, the decidualized endometrial lining is shed or, as is the case with species that follow the estrous cycle, absorbed. In menstruating species, decidualization is spontaneous and occurs as a result of maternal hormones. In non-menstruating species, decidualization is non-spontaneous, meaning it only happens after there are external signals from an implanted embryo. |
Autophagy database Use in bioinformatics Autophagy_database > Use in bioinformatics Given that these databases are a large store of biological information, these can be used in bioinformatics applications to simplify information collection and analysis. Bioinformatics looks to pair biological discoveries with big data, to aid in improved scientific discoveries. Each database can be utilized to study an autophagic protein or gene of interest, where these databases are maintained by user submissions. |
Chemotherapy Dosage Chemotherapy > Treatment strategies > Dosage Because of their higher BSA, clinicians often arbitrarily reduce the dose prescribed by the BSA formula for fear of overdosing. In many cases, this can result in sub-optimal treatment.Several clinical studies have demonstrated that when chemotherapy dosing is individualized to achieve optimal systemic drug exposure, treatment outcomes are improved and toxic side effects are reduced. In the 5-FU clinical study cited above, people whose dose was adjusted to achieve a pre-determined target exposure realized an 84% improvement in treatment response rate and a six-month improvement in overall survival (OS) compared with those dosed by BSA. |
Normalisable wavefunction Historical background Normalized_wavefunction > Historical background In 1900, Max Planck postulated the proportionality between the frequency f {\displaystyle f} of a photon and its energy E {\displaystyle E} , E = h f {\displaystyle E=hf} , and in 1916 the corresponding relation between a photon's momentum p {\displaystyle p} and wavelength λ {\displaystyle \lambda } , λ = h p {\displaystyle \lambda ={\frac {h}{p}}} , where h {\displaystyle h} is the Planck constant. In 1923, De Broglie was the first to suggest that the relation λ = h p {\displaystyle \lambda ={\frac {h}{p}}} , now called the De Broglie relation, holds for massive particles, the chief clue being Lorentz invariance, and this can be viewed as the starting point for the modern development of quantum mechanics. The equations represent wave–particle duality for both massless and massive particles. In the 1920s and 1930s, quantum mechanics was developed using calculus and linear algebra. |
Β+ decay Angular momentum Beta_decay > Conservation rules for beta decay > Angular momentum For allowed decays, the net orbital angular momentum is zero, hence only spin quantum numbers are considered. The electron and antineutrino are fermions, spin-1/2 objects, therefore they may couple to total S = 1 {\displaystyle S=1} (parallel) or S = 0 {\displaystyle S=0} (anti-parallel). For forbidden decays, orbital angular momentum must also be taken into consideration. |
Polycistronic mRNA Nonsense-mediated decay Polycistronic_mRNA > Degradation > Nonsense-mediated decay Eukaryotic messages are subject to surveillance by nonsense-mediated decay (NMD), which checks for the presence of premature stop codons (nonsense codons) in the message. These can arise via incomplete splicing, V(D)J recombination in the adaptive immune system, mutations in DNA, transcription errors, leaky scanning by the ribosome causing a frame shift, and other causes. Detection of a premature stop codon triggers mRNA degradation by 5' decapping, 3' poly(A) tail removal, or endonucleolytic cleavage. |
Calculator application Computer algebra systems Calculator_application > Related software packages > Computer algebra systems Computer algebra systems are not normally called calculators because their main purpose is to perform symbolic manipulation of mathematical expressions that can contain variables and complex operations, such as integration. However, the expressions can be basic calculations that do not use variables, and that are simply evaluated, as with a calculator. |
AeroLift CycloCrane Design and development AeroLift_CycloCrane > Design and development The stalks are gradually rotated in the opposite direction causing them to act as a propeller again to take the ship back into rotation and hover. The load is then released and the ship can return for another load or if the ship is to be moored it can be secured to a tether or mast. Both versions of the CycloCrane were 178 ft (54.25 m) long. |
Jahn–Teller distortion Implications for dynamics Jahn–Teller_distortion > Theory > Potential energy surfaces > Implications for dynamics Here the nonadiabatic couplings become very large and the behaviour of the system cannot be described within the familiar Born–Oppenheimer (BO) separation between the electronic and nuclear motions. The nuclear motion ceases to be confined to a single, well-defined APES and the transitions between the adiabatic surfaces occur yielding effects like Slonzcewsky resonances. In molecules this is usually a femtosecond timescale, which amounts to ultrafast (femtosecond) internal conversion processes, accompanied by broad spectral bands also under isolated-molecule conditions and highly complex spectral features. |
Tissue hypoxia Summary Hypoxic_tissue Hypoxia in which there is complete absence of oxygen supply is referred to as anoxia. Hypoxia can be due to external causes, when the breathing gas is hypoxic, or internal causes, such as reduced effectiveness of gas transfer in the lungs, reduced capacity of the blood to carry oxygen, compromised general or local perfusion, or inability of the affected tissues to extract oxygen from, or metabolically process, an adequate supply of oxygen from an adequately oxygenated blood supply. Generalized hypoxia occurs in healthy people when they ascend to high altitude, where it causes altitude sickness leading to potentially fatal complications: high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE). |
Microsoft Active Accessibility Challenges and limitations Microsoft_Active_Accessibility > Challenges and limitations MSAA represents the UI as a hierarchy of accessible objects in a manner similar to Windows' Window Manager. Clients navigate from one accessible object to another using the IAccessible::accNavigate method. However, servers implemented accNavigate in unpredictable ways and often not at all. |
Epigenetic regulation of neurogenesis Histone modifications Epigenetic_regulation_of_neurogenesis > Embryonic neurogenesis > Histone modifications Mutant analysis has shown that histone methylation modulates the production of deep layer and upper layer neurons through epigenetic regulation. Specifically, deletion of a portion of the PRC2 complex, Ezh2, encoding histone methyltransferase, led to a twofold reduction of POU3F2/BRN2-expressing and SATB2-expressing upper layer neurons without affecting the number of neurons in layers V and VI . In mouse embryonic stem cell-derived neural progenitors, increased histone acetylation induced by the histone deacetylase (HDAC) inhibitor valproic acid not only induced neuronal differentiation, but also selectively enriched the upper layer neuronal population. Therefore, it has been proposed that HDAC inhibition promotes the progression of neuronal differentiation, leading to a fate-switch from deep-layer producing progenitors into upper-layer progenitors. However, the reasons behind this selective differentiation and timing control as a result of HDAC inhibition are not yet fully understood. |
Second-order differential equation History Differential_equation > History Lagrange solved this problem in 1755 and sent the solution to Euler. Both further developed Lagrange's method and applied it to mechanics, which led to the formulation of Lagrangian mechanics. In 1822, Fourier published his work on heat flow in Théorie analytique de la chaleur (The Analytic Theory of Heat), in which he based his reasoning on Newton's law of cooling, namely, that the flow of heat between two adjacent molecules is proportional to the extremely small difference of their temperatures. Contained in this book was Fourier's proposal of his heat equation for conductive diffusion of heat. This partial differential equation is now a common part of mathematical physics curriculum. |
NMR Chemical Shift Re-referencing General References Nuclear_magnetic_resonance_chemical_shift_re-referencing > General References "The C-13 chemical-shift index - a simple method for the identification of protein secondary structure using C-13 chemical-shift data". Journal of Biomolecular NMR. 4 (2): 171–180. |
Thermal management (electronics) Thermal interface material Heat_dissipation > Overview > Thermal interface material A thermal interface material or mastic (aka TIM) is used to fill the gaps between thermal transfer surfaces, such as between microprocessors and heatsinks, in order to increase thermal transfer efficiency. It has a higher thermal conductivity value in Z-direction than xy-direction. |
Amazon SimpleDB Limitations Amazon_SimpleDB > Limitations partition tolerance – components in the system are connected to one another by a computer network. If components are not able to contact one another using the network (a condition known as a network partition), operation of the system will continue.Component failures are assumed to be inevitable; thus, both of these properties were deemed necessary in order to provide a reliable web service. The CAP theorem states that it is not possible for a system to exhibit these properties along with consistency; thus, the designers needed to settle for a weaker form of consistency. Published limitations: |
Ecological selection Circumstances in which it occurs Ecological_selection > Circumstances in which it occurs Each of these is a vehicle for ecological selection to do its work in the course of evolution. However, ecological selection can be much more specific, not only working within species but within populations, even populations in the same region. For example, scientists in Quebec recently examined how tree seedlings react to different nitrate levels. |
Mitotic phase Forms of mitosis Mitosis > Variations > Forms of mitosis Closed orthomitosis is found among diatoms, ciliates, some Microsporidia, unicellular yeasts and some multicellular fungi. Semiopen pleuromitosis is typical of most Apicomplexa. Semiopen orthomitosis occurs with different variants in some amoebae (Lobosa) and some green flagellates (e.g., Raphidophyta or Volvox). Open orthomitosis is typical in mammals and other Metazoa, and in land plants; but it also occurs in some protists. |
Generalizability theory Overview Generalizability_theory > Overview The usefulness of data gained from a G study is crucially dependent on the design of the study. Therefore, the researcher must carefully consider the ways in which he/she hopes to generalize any specific results. Is it important to generalize from one setting to a larger number of settings? |
Stem and leaf plot Summary Stem-and-leaf_plot The popularity during those years is attributable to their use of monospaced (typewriter) typestyles that allowed computer technology of the time to easily produce the graphics. Modern computers' superior graphic capabilities have meant these techniques are less often used. This plot has been implemented in Octave and R.A stem-and-leaf plot is also called a stemplot, but the latter term often refers to another chart type. A simple stem plot may refer to plotting a matrix of y values onto a common x axis, and identifying the common x value with a vertical line, and the individual y values with symbols on the line.Unlike histograms, stem-and-leaf displays retain the original data to at least two significant digits, and put the data in order, thereby easing the move to order-based inference and non-parametric statistics. |
Drug-resistant TB Summary Multidrug-resistant_TB Multidrug-resistant tuberculosis (MDR-TB) is a form of tuberculosis (TB) infection caused by bacteria that are resistant to treatment with at least two of the most powerful first-line anti-TB medications (drugs): isoniazid and rifampin. Some forms of TB are also resistant to second-line medications, and are called extensively drug-resistant TB (XDR-TB).Tuberculosis is caused by infection with the bacterium Mycobacterium tuberculosis. Almost one in four people in the world are infected with TB bacteria. Only when the bacteria become active do people become ill with TB. |
Adrenal cortex Layers Adrenal_cortex > Layers The synthesis and secretion of aldosterone are mainly regulated by the renin–angiotensin–aldosterone system. The zona glomerulosa cells express a specific enzyme aldosterone synthase (also known as CYP11B2). Aldosterone is largely responsible for the long-term regulation of blood pressure. |
AI@50 Selected Submitted Papers: Future Possibilities for AI AI@50 > Conference Program and links to published papers > Selected Submitted Papers: Future Possibilities for AI Eric Steinhart, Survival as a Digital Ghost Colin T. A. Schmidt, Did You Leave That 'Contraption' Alone With Your Little Sister? Michael Anderson & Susan Leigh Anderson, The Status of Machine Ethics Marcello Guarini, Computation, Coherence, and Ethical Reasoning |
Brian G. Gardiner (meteorologist) Summary Brian_G._Gardiner_(meteorologist) Brian Gerard Gardiner is a retired British meteorologist, formerly working for the British Antarctic Survey. Together with Joe Farman and Jonathan Shanklin he discovered the "Ozone Hole". Their results were first published on 16 May 1985. They won the Chree medal and prize in 2001. == References == |
Slenderness ratio Summary Slenderness_ratio Slenderness captures the influence on buckling of all the geometric aspects of the column, namely its length, area, and second moment of area. The influence of the material is represented separately by the material's modulus of elasticity E {\displaystyle E} . Structural engineers generally consider a skyscraper as slender if the height:width ratio exceeds 10:1 or 12:1. Slim towers require the adoption of specific measures to counter the high strengths of wind in the vertical cantilever, like including additional structures to endow greater rigidity to the building or diverse types of tuned mass dampers to avoid unwanted swinging.Tall buildings with high slenderness ratio are sometime referred to as pencil towers. |
Proof of identity (blockchain consensus) The proof of identity Proof_of_identity_(blockchain_consensus) > Biometric data-based proofs > The proof of identity The system can be implemented according to CanDID methodology.The proof of identity addresses the problems with the proof of personhood and UniqueID, however, there are some challenges and possible criticisms to consider: The amount of data to store in the blockchain is considerable and may require some daily downtime for cohort leader servers to reboot. The system includes the creation of a PoID global organization that facilitates the kick-off of identification venues and rules out rare biometric disputes. This may be seen as a center of authority. |
Generalised beam theory Description Generalised_beam_theory > Description The theory can be applied without restrictions to any prismatic thin-walled structural member exhibiting straight or curved axial axis (any loading, any cross-section geometry, any boundary conditions). GBT is in some ways analogous to the finite strip method and can be a more computationally efficient method than modeling a beam with a full 2D or 3D finite element method to predict the member structural behavior. GBT has been widely recognized as an efficient approach to analyzing thin-walled members and structural systems. |
Scientific realism Constructivist epistemology Scientific_realism > Arguments for and against scientific realism > Constructivist epistemology Social constructivists might argue that scientific realism is unable to account for the rapid change that occurs in scientific knowledge during periods of scientific revolution. Constructivists may also argue that the success of theories is only a part of the construction. However, these arguments ignore the fact that many scientists are not realists. During the development of quantum mechanics in the 1920s, the dominant philosophy of science was logical positivism. The alternative realist Bohm interpretation and many-worlds interpretation of quantum mechanics do not make such a revolutionary break with the concepts of classical physics. |
Andrey Kolmogorov Adulthood Andrey_Kolmogorov > Biography > Adulthood In 1971, Kolmogorov joined an oceanographic expedition aboard the research vessel Dmitri Mendeleev. He wrote a number of articles for the Great Soviet Encyclopedia. In his later years, he devoted much of his effort to the mathematical and philosophical relationship between probability theory in abstract and applied areas.Kolmogorov died in Moscow in 1987 and his remains were buried in the Novodevichy cemetery. |
Energy functional Summary Energy_functional This energy is a scalar quantity, a function of the state, hence the term functional. The system tends to develop from the state with higher energy (higher cost) to the state with lower energy, thus local minima of this functional are usually related to the stable stationary states. Studying such states is part of the optimization problems, where the terms energy functional or cost functional are often used to describe the objective function. |
Tree stack automaton Summary Tree_stack_automaton A tree stack automaton (plural: tree stack automata) is a formalism considered in automata theory. It is a finite state automaton with the additional ability to manipulate a tree-shaped stack. It is an automaton with storage whose storage roughly resembles the configurations of a thread automaton. A restricted class of tree stack automata recognises exactly the languages generated by multiple context-free grammars (or linear context-free rewriting systems). |
Space diagonal Space diagonals of magic cubes Space_diagonal > Space diagonals of magic cubes A magic square is an arrangement of numbers in a square grid so that the sum of the numbers along every row, column, and diagonal is the same. Similarly, one may define a magic cube to be an arrangement of numbers in a cubical grid so that the sum of the numbers on the four space diagonals must be the same as the sum of the numbers in each row, each column, and each pillar. |
Protein–ligand complex Functions Protein–ligand_complex > Functions Protein–ligand complexes can be found in almost any cellular process. Binding of a ligand causes a conformational change in the protein and often also in the ligand. This change initiates a sequence of events leading to different cellular functions. |
Fock state Vacuum fluctuations Photon_number > Vacuum fluctuations Thus it is easy to see that the expectation values of these field operators vanishes in the vacuum state: ⟨ 0 | F | 0 ⟩ = 0 {\displaystyle \langle 0|F|0\rangle =0} However, it can be shown that the expectation values of the square of these field operators is non-zero. Thus there are fluctuations in the field about the zero ensemble average. These vacuum fluctuations are responsible for many interesting phenomenon including the Lamb shift in quantum optics. |
Model risk Testing Model_risk > Mitigation > Testing Stress testing and backtesting. Avoid letting small issues snowball into large issues later on. Independent validation Ongoing monitoring and against market |
Gravitational contact terms Summary Gravitational_contact_terms The contact term then generates a correction to the full action of the theory. Contact terms occur in gravity when there are non-minimal interactions, ( M P l a n c k 2 + α ϕ 2 ) R {\displaystyle (M_{Planck}^{2}+\alpha \phi ^{2})R} , or in Brans-Dicke Theory, ( M P l a n c k 2 + κ M P l a n c k Φ ) R {\displaystyle (M_{Planck}^{2}+\kappa M_{Planck}\Phi )R} . The non-minimal couplings are quantum equivalent to an "Einstein frame," with a pure Einstein-Hilbert action, M P l a n c k 2 R {\displaystyle M_{Planck}^{2}R} , owing to gravitational contact terms. |
Field aligned current Summary Field_aligned_current A Birkeland current (also known as field-aligned current) is a set of electrical currents that flow along geomagnetic field lines connecting the Earth's magnetosphere to the Earth's high latitude ionosphere. In the Earth's magnetosphere, the currents are driven by the solar wind and interplanetary magnetic field and by bulk motions of plasma through the magnetosphere (convection indirectly driven by the interplanetary environment). The strength of the Birkeland currents changes with activity in the magnetosphere (e.g. during substorms). Small scale variations in the upward current sheets (downward flowing electrons) accelerate magnetospheric electrons which, when they reach the upper atmosphere, create the Auroras Borealis and Australis. |
Matrix decomposition Singular value decomposition Matrix_decomposition > Decompositions based on eigenvalues and related concepts > Singular value decomposition Applicable to: m-by-n matrix A. Decomposition: A = U D V ∗ {\displaystyle A=UDV^{*}} , where D is a nonnegative diagonal matrix, and U and V satisfy U ∗ U = I , V ∗ V = I {\displaystyle U^{*}U=I,V^{*}V=I} . Here V ∗ {\displaystyle V^{*}} is the conjugate transpose of V (or simply the transpose, if V contains real numbers only), and I denotes the identity matrix (of some dimension). Comment: The diagonal elements of D are called the singular values of A. Comment: Like the eigendecomposition above, the singular value decomposition involves finding basis directions along which matrix multiplication is equivalent to scalar multiplication, but it has greater generality since the matrix under consideration need not be square. Uniqueness: the singular values of A {\displaystyle A} are always uniquely determined. U {\displaystyle U} and V {\displaystyle V} need not to be unique in general. |
Classifier system Methodology Learning_classifier_system > Methodology As a result, the LCS paradigm can be flexibly applied to many problem domains that call for machine learning. The major divisions among LCS implementations are as follows: (1) Michigan-style architecture vs. Pittsburgh-style architecture, (2) reinforcement learning vs. supervised learning, (3) incremental learning vs. batch learning, (4) online learning vs. offline learning, (5) strength-based fitness vs. accuracy-based fitness, and (6) complete action mapping vs best action mapping. These divisions are not necessarily mutually exclusive. For example, XCS, the best known and best studied LCS algorithm, is Michigan-style, was designed for reinforcement learning but can also perform supervised learning, applies incremental learning that can be either online or offline, applies accuracy-based fitness, and seeks to generate a complete action mapping. |
Heat sinks Experimental methods Heat_sink > Methods to determine performance > Experimental methods Experimental tests are one of the more popular ways to determine the heat sink thermal performance. In order to determine the heat sink thermal resistance, the flow rate, input power, inlet air temperature and heat sink base temperature need to be known. Vendor-supplied data is commonly provided for ducted test results. However, the results are optimistic and can give misleading data when heat sinks are used in an unducted application. More details on heat sink testing methods and common oversights can be found in Azar, et al. |
Equilibrium state Cited bibliography Thermodynamical_equilibrium > Cited bibliography An Advanced Treatise, ed. H. Eyring, D. Henderson, W. Jost, Academic Press, New York, lcn 73–117081. Kirkwood, J.G., Oppenheim, I. |
Nucleophilic catalysis Proton donors or acceptors Enzyme_catalysis > Mechanisms of an alternative reaction route > Proton donors or acceptors It is important to clarify that the modification of the pKa's is a pure part of the electrostatic mechanism. Furthermore, the catalytic effect of the above example is mainly associated with the reduction of the pKa of the oxyanion and the increase in the pKa of the histidine, while the proton transfer from the serine to the histidine is not catalyzed significantly, since it is not the rate determining barrier. Note that in the example shown, the histidine conjugate acid acts as a general acid catalyst for the subsequent loss of the amine from a tetrahedral intermediate. Evidence supporting this proposed mechanism (Figure 4 in Ref. 13) has, however been controverted. |
Null hypothesis Goals of null hypothesis tests Exclusion_of_the_null_hypothesis > Goals of null hypothesis tests If not true, the theory of the early universe may need revision. Null hypotheses of homogeneity are used to verify that multiple experiments are producing consistent results. For example, the effect of a medication on the elderly is consistent with that of the general adult population. |
Prion protein Interactions Prion_protein > Interactions A strong interaction exists between PrP and the cochaperone Hop (Hsp70/Hsp90 organizing protein; also called STI1 (Stress-induced protein 1)). |
Index of protein-related articles Nutrition Index_of_protein-related_articles > Nutrition Carbohydrates (nutrient), role of protein in nutrition Soy protein, storage protein held in discrete particles called protein bodies Whey protein, the name for a collection of globular proteins that can be isolated from whey |
Quasi-experiment Ethics Quasi-experiment > Ethics A quasi-experiment generally does not involve actual randomization.Quasi-experiments have outcome measures, treatments, and experimental units, but do not use random assignment. Quasi-experiments are often the design that most people choose over true experiments. It is usually easily conducted as opposed to true experiments, because they bring in features from both experimental and non-experimental designs. Measured variables as well as manipulated variables can be brought in. Usually quasi-experiments are chosen by experimenters because they maximize internal and external validity. |
Baroreflex activation therapy Medical uses Baroreflex_activation_therapy > Medical uses Baroreflex activation therapy is used to reduce the symptoms of heart failure in patients who do not qualify for cardiac resynchronization therapy. |
Complex-base system Base −1 ± i Complex-base_system > Base −1 ± i Of particular interest are the quater-imaginary base (base 2i) and the base −1 ± i systems discussed below, both of which can be used to finitely represent the Gaussian integers without sign. Base −1 ± i, using digits 0 and 1, was proposed by S. Khmelnik in 1964 and Walter F. Penney in 1965. |
Coreolis effect Corollaries Coriolis_Force > Formula > Corollaries For example, on Earth, this situation occurs for a body at the equator falling downward, as in the Dechales illustration above, where the falling ball travels further to the east than does the tower. if the velocity is straight outward from the axis, the Coriolis force is against the direction of local rotation. In the tower example, a ball launched upward would move toward the west. |
Income inequality metrics Common income inequality metrics Income_inequality_metrics > Common income inequality metrics Among the most common metrics used to measure inequality are the Gini index (also known as Gini coefficient), the Theil index, and the Hoover index. They have all four properties described above. An additional property of an inequality metric that may be desirable from an empirical point of view is that of 'decomposability'. |
MadeInGermany Summary MadeInGermany For this undertaking, a new vehicle has been designed to meet the criteria for a city approval to drive autonomously on real roads. The vehicle was named MadeInGermany and has driven over 3,000 kilometers autonomously on Berlin’s city roads and highways with no human intervention. The primary goal is to operate autonomously in urban environments with dense human traffic and obeying traffic regulations. In order to obtain the permission to drive autonomously and freely in daily traffic alongside other traffic participants, the sensors have been primarily mounted inside the car’s body. MadeInGermany was also a test vehicle for semi-autonomous control, being remote controlled with an iPad app or a Brain–computer interface. |
Eye movement in music reading Summary Eye_movement_in_music_reading Saccades are separated from each other by fixations, during which the eyes are relatively stationary on the page. It is well established that the perception of visual information occurs almost entirely during fixations and that little if any information is picked up during saccades. Fixations comprise about 90% of music reading time, typically averaging 250–400 ms in duration.Eye movement in music reading is an extremely complex phenomenon that involves a number of unresolved issues in psychology, and which requires intricate experimental conditions to produce meaningful data. Despite some 30 studies in this area over the past 70 years, little is known about the underlying patterns of eye movement in music reading. |
Compressive strength Summary Compression_strength In mechanics, compressive strength (or compression strength) is the capacity of a material or structure to withstand loads tending to reduce size (as opposed to tensile strength which withstands loads tending to elongate). In other words, compressive strength resists compression (being pushed together), whereas tensile strength resists tension (being pulled apart). In the study of strength of materials, tensile strength, compressive strength, and shear strength can be analyzed independently. Some materials fracture at their compressive strength limit; others deform irreversibly, so a given amount of deformation may be considered as the limit for compressive load. |
Chemical Science Industry Applied_Chemistry > Practice > Industry The chemical industry represents an important economic activity worldwide. The global top 50 chemical producers in 2013 had sales of US$980.5 billion with a profit margin of 10.3%. |
Astronomical albedo Trees Astronomical_albedo > Examples of terrestrial albedo effects > Trees The water vapor causes cooling on the land surface, causes heating where it condenses, acts a strong greenhouse gas, and can increase albedo when it condenses into clouds. Scientists generally treat evapotranspiration as a net cooling impact, and the net climate impact of albedo and evapotranspiration changes from deforestation depends greatly on local climate.Mid-to-high-latitude forests have a much lower albedo during snow seasons than flat ground, thus contributing to warming. |
Journal of Statistical Physics Summary Journal_of_Statistical_Physics Phys., vol. 21(6), 669–706, (1979). Times Cited: 1,071 Wertheim, MS, Fluids with highly directional attractive forces. |
Grounding in communication Grounding in conversation Grounding_in_communication > Elements of theory > Grounding in conversation Grounding in communication theory has described conversation as a form of collaborative action. While grounding in communication theory has been applied to mediated communication, the theory primarily addresses face-to-face conversation. Groups working together will ground their conversations by coming up with common ground or mutual knowledge. The members will utilize this knowledge in order to contribute to a more efficient dialogue. |
Span loading Effect on turning performance Wing_loading > Effect on performance > Effect on turning performance Like any body in circular motion, an aircraft that is fast and strong enough to maintain level flight at speed v in a circle of radius R accelerates towards the center at v 2 R {\displaystyle \scriptstyle {\frac {v^{2}}{R}}} . That acceleration is caused by the inward horizontal component of the lift, L s i n θ {\displaystyle \scriptstyle Lsin\theta } , where θ {\displaystyle \theta } is the banking angle. Then from Newton's second law, Solving for R gives The lower the wing loading, the tighter the turn. |
Discrete-event simulation State Discrete_event_simulation > Components > State A system state is a set of variables that captures the salient properties of the system to be studied. The state trajectory over time S(t) can be mathematically represented by a step function whose value can change whenever an event occurs. |
Nonstructural estimation Methods Nonstructural_estimation > Methods One of the fundamental statistical methods used by econometricians is regression analysis. Regression methods are important in econometrics because economists typically cannot use controlled experiments. Econometricians often seek illuminating natural experiments in the absence of evidence from controlled experiments. Observational data may be subject to omitted-variable bias and a list of other problems that must be addressed using causal analysis of simultaneous-equation models. |
Radial basis function network Summary Radial_basis_function_network In the field of mathematical modeling, a radial basis function network is an artificial neural network that uses radial basis functions as activation functions. The output of the network is a linear combination of radial basis functions of the inputs and neuron parameters. Radial basis function networks have many uses, including function approximation, time series prediction, classification, and system control. They were first formulated in a 1988 paper by Broomhead and Lowe, both researchers at the Royal Signals and Radar Establishment. |
Genomic instability The usual genome situation Genome_instability > The usual genome situation Usually, all cells in an individual in a given species (plant or animal) show a constant number of chromosomes, which constitute what is known as the karyotype defining this species (see also List of number of chromosomes of various organisms), although some species present a very high karyotypic variability. In humans, mutations that would change an amino acid within the protein coding region of the genome occur at an average of only 0.35 per generation (less than one mutated protein per generation).Sometimes, in a species with a stable karyotype, random variations that modify the normal number of chromosomes may be observed. In other cases, there are structural alterations (e.g., chromosomal translocations, deletions) that modify the standard chromosomal complement. In these cases, it is indicated that the affected organism presents genome instability (also genetic instability, or even chromosomic instability). The process of genome instability often leads to a situation of aneuploidy, in which the cells present a chromosomic number that is either higher or lower than the normal complement for the species. |
Prosolvable group Examples Prosolvable_group > Examples Let p be a prime, and denote the field of p-adic numbers, as usual, by Q p {\displaystyle \mathbf {Q} _{p}} . Then the Galois group Gal ( Q ¯ p / Q p ) {\displaystyle {\text{Gal}}({\overline {\mathbf {Q} }}_{p}/\mathbf {Q} _{p})} , where Q ¯ p {\displaystyle {\overline {\mathbf {Q} }}_{p}} denotes the algebraic closure of Q p {\displaystyle \mathbf {Q} _{p}} , is prosolvable. This follows from the fact that, for any finite Galois extension L {\displaystyle L} of Q p {\displaystyle \mathbf {Q} _{p}} , the Galois group Gal ( L / Q p ) {\displaystyle {\text{Gal}}(L/\mathbf {Q} _{p})} can be written as semidirect product Gal ( L / Q p ) = ( R ⋊ Q ) ⋊ P {\displaystyle {\text{Gal}}(L/\mathbf {Q} _{p})=(R\rtimes Q)\rtimes P} , with P {\displaystyle P} cyclic of order f {\displaystyle f} for some f ∈ N {\displaystyle f\in \mathbf {N} } , Q {\displaystyle Q} cyclic of order dividing p f − 1 {\displaystyle p^{f}-1} , and R {\displaystyle R} of p {\displaystyle p} -power order. Therefore, Gal ( L / Q p ) {\displaystyle {\text{Gal}}(L/\mathbf {Q} _{p})} is solvable. |
Ulnar deviation Summary Ulnar_deviation Ulnar deviation, also known as ulnar drift, is a hand deformity in which the swelling of the metacarpophalangeal joints (the big knuckles at the base of the fingers) causes the fingers to become displaced, tending towards the little finger. Its name comes from the displacement toward the ulna (as opposed to radial deviation, in which fingers are displaced toward the radius). Ulnar deviation is likely to be a characteristic of rheumatoid arthritis, more than of osteoarthritis. |
Sub domain Overview Sub_domain > Overview The Domain Name System (DNS) has a tree structure or hierarchy, which includes nodes on the tree being a domain name. A subdomain is a domain that is part of a larger domain. Each label may contain from 0 to 63 octets. The full domain name may not exceed a total length of 253 ASCII characters in its textual representation.Subdomains are defined by editing the DNS zone file pertaining to the parent domain. |
Cockayne's syndrome Laboratory Studies Cockayne's_syndrome > Diagnosis > Laboratory Studies In Cockayne syndrome patients, UV-irradiated cells show decreased DNA and RNA synthesis. https://emedicine.medscape.com/article/1115866-workup#c5 Laboratory studies are mainly useful to eliminate other disorders. For example, skeletal radiography, endocrinologic tests, and chromosomal breakage studies can help in excluding disorders included in the differential diagnosis. |
Virus genome Epidemiology Virus > Role in human disease > Epidemiology The rate or speed of transmission of viral infections depends on factors that include population density, the number of susceptible individuals, (i.e., those not immune), the quality of healthcare and the weather.Epidemiology is used to break the chain of infection in populations during outbreaks of viral diseases. Control measures are used that are based on knowledge of how the virus is transmitted. It is important to find the source, or sources, of the outbreak and to identify the virus. |
By inspection Philosophy of mathematics Angle_chasing > Philosophy of mathematics The concept of "elementary proof" is used specifically in number theory, where it usually refers to a proof that does not resort to methods from complex analysis. folklore A result is called "folklore" if it is non-obvious, non-published, yet somehow generally known to the specialists within a field. In many scenarios, it is unclear as to who first obtained the result, though if the result is significant, it may eventually find its way into the textbooks, whereupon it ceases to be folklore.Many of the results mentioned in this paper should be considered "folklore" in that they merely formally state ideas that are well-known to researchers in the area, but may not be obvious to beginners and to the best of my knowledge do not appear elsewhere in print. |
Carroll's paradox Summary Carroll's_paradox In physics, Carroll's paradox arises when considering the motion of a falling rigid rod that is specially constrained. Considered one way, the angular momentum stays constant; considered in a different way, it changes. It is named after Michael M. Carroll who first published it in 1984. |
Fatigue Avoidance Scheduling Tool History Fatigue_Avoidance_Scheduling_Tool > History However, all of these applications involved experts or personnel that they had trained. Attempts to apply FAST to daily flying scheduling operations were unsuccessful because the user interface was designed originally for scientists, not for operators. The Federal Railroad Administration sponsored a major evaluation of the SAFTE biomathematical fatigue model (or simulation) to determine if it could predict increased risk of railroad accidents based on work schedule information (Hursh, Raslear et al., 2006). |
Axonal projection Clinical significance Axonal_initial_segment > Clinical significance The dysfunction of axons in the nervous system is one of the major causes of many inherited and acquired neurological disorders that affect both peripheral and central neurons.When an axon is crushed, an active process of axonal degeneration takes place at the part of the axon furthest from the cell body. This degeneration takes place quickly following the injury, with the part of the axon being sealed off at the membranes and broken down by macrophages. This is known as Wallerian degeneration. |
Hemostasis Steps of mechanism Hemostasis > Steps of mechanism Platelets are a large factor in the hemostatic process. They allow for the creation of the "platelet plug" that forms almost directly after a blood vessel has been ruptured. Within seconds of a blood vessel's epithelial wall being disrupted, platelets begin to adhere to the sub-endothelium surface. |
Digital Identity Trust, authentication and authorization Digital_Identity > Technical aspects > Trust, authentication and authorization In order to assign a digital representation to an entity, the attributing party must trust that the claim of an attribute (such as name, location, role as an employee, or age) is correct and associated with the person or thing presenting the attribute. Conversely, the individual claiming an attribute may only grant selective access to its information (e.g., proving identity in a bar or PayPal authentication for payment at a website). In this way, digital identity is better understood as a particular viewpoint within a mutually-agreed relationship than as an objective property. |
Muscle fatigue Metabolites Muscle_fatigue > Metabolic fatigue > Metabolites Metabolites are the substances (generally waste products) produced as a result of muscular contraction. They include chloride, potassium, lactic acid, ADP, magnesium (Mg2+), reactive oxygen species, and inorganic phosphate. Accumulation of metabolites can directly or indirectly produce metabolic fatigue within muscle fibers through interference with the release of calcium (Ca2+) from the sarcoplasmic reticulum or reduction of the sensitivity of contractile molecules actin and myosin to calcium. |
Stress analysis Simplifications Stress_analysis > Mathematical methods > Simplifications Stress analysis is simplified when the physical dimensions and the distribution of loads allow the structure to be treated as one- or two-dimensional. In the analysis of a bridge, its three dimensional structure may be idealized as a single planar structure, if all forces are acting in the plane of the trusses of the bridge. Further, each member of the truss structure might then be treated a uni-dimensional members with the forces acting along the axis of each member. In which case, the differential equations reduce to a finite set of equations with finitely many unknowns. |
Decision trees Optimizing a decision tree Decision_trees > Optimizing a decision tree The leaves will represent the final classification decision the model has produced based on the mutations a sample either has or does not have. The left tree is the decision tree we obtain from using information gain to split the nodes and the right tree is what we obtain from using the phi function to split the nodes. Now assume the classification results from both trees are given using a confusion matrix. |
Hydrogen-like atom Solution to Dirac equation Hydrogen-like_atom > Solution to Dirac equation The modifications of the energy due to using the Dirac equation rather than the Schrödinger solution is of the order of α2, and for this reason α is called the fine-structure constant. The solution to the Dirac equation for quantum numbers n, k, and m, is: where the Ωs are columns of the two spherical harmonics functions shown to the right. |
Session Initiation Protocol Protocol operation Session_Initiation_Protocol > Protocol operation SIP reuses most of the header fields, encoding rules and status codes of HTTP, providing a readable text-based format. SIP can be carried by several transport layer protocols including Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and Stream Control Transmission Protocol (SCTP). SIP clients typically use TCP or UDP on port numbers 5060 or 5061 for SIP traffic to servers and other endpoints. |
Friction drag Definition Skin_friction > Skin friction coefficient > Definition A fundamental fact in aerodynamics states that ( τ w ) l a m i n a r < ( τ w ) t u r b u l e n t {\displaystyle ({\tau _{w}})_{laminar}<({\tau _{w}})_{turbulent}} . This immediately implies that laminar skin friction drag is smaller than turbulent skin friction drag, for the same inflow. The skin friction coefficient is a strong function of the Reynolds number R e {\displaystyle Re} , as R e {\displaystyle Re} increases c f {\displaystyle c_{f}} decreases. |
Cloud computing architecture Software as a service (SaaS) Cloud_computing_architecture > Delivery > Software as a service (SaaS) The software-as-a-service (SaaS) service-model involves the cloud provider installing and maintaining software in the cloud and users running the software from cloud over the Internet (or Intranet). The users' client machines require no installation of any application-specific software since cloud applications run in the cloud. SaaS is scalable, and system administrators may load the applications on several servers. In the past, each customer would purchase and load their own copy of the application to each of their own servers, but with the SaaS the customer can access the application without installing the software locally. |
Mathematical algorithm Formal versus empirical Algorithm_design > Algorithmic analysis > Formal versus empirical The analysis, and study of algorithms is a discipline of computer science, and is often practiced abstractly without the use of a specific programming language or implementation. In this sense, algorithm analysis resembles other mathematical disciplines in that it focuses on the underlying properties of the algorithm and not on the specifics of any particular implementation. Usually pseudocode is used for analysis as it is the simplest and most general representation. However, ultimately, most algorithms are usually implemented on particular hardware/software platforms and their algorithmic efficiency is eventually put to the test using real code. |
Creep-testing machine Applications Creep-testing_machine > Applications Creep machines are most commonly used in experiments to determine how efficient and stable a material is. The machine is used by students and companies to create a creep curve on how much pressure and stress a material can handle. The machine is able to calculate the stress rate, time and pressure.Creep testing has three different applications in the industry: Displacement-Limited applications: the size must be precise and there must be little errors or tendency to change. |
Multiple Virtual Storage MVS filesystem Multiple_Virtual_Storage > MVS filesystem That is, Unix programs using fopen() can access an MVS dataset and a user can allocate a Unix file as though it were a dataset, with some restrictions. The Hierarchical File System (HFS) (not to be confused with Apple's Hierarchical File System) uses a unique type of dataset, while the newer z/OS File System (zFS) (not to be confused with Sun's ZFS) uses a VSAM Linear Data Set (LDS). Programs running on network-connected computers (such as the IBM AS/400) can use local data management interfaces to transparently create, manage, and access VSAM record-oriented files by using client-server products implemented according to Distributed Data Management Architecture (DDM). DDM is also the base architecture for the MVS DB2 server that implements Distributed Relational Database Architecture (DRDA). |
QUIC Background QUIC > Background Transmission Control Protocol, or TCP, aims to provide an interface for sending streams of data between two endpoints. Data is handed to the TCP system, which ensures the data makes it to the other end in exactly the same form, or the connection will indicate that an error condition exists.To do this, TCP breaks up the data into network packets and adds small amounts of data to each packet. This additional data includes a sequence number that is used to detect packets that are lost or arrive out of order, and a checksum that allows the errors within packet data to be detected. When either problem occurs, TCP uses automatic repeat request (ARQ) to tell the sender to re-send the lost or damaged packet.In most implementations, TCP will see any error on a connection as a blocking operation, stopping further transfers until the error is resolved or the connection is considered failed. |
Metric unit Background Metric_symbol > Background Derived units may have their own unit name, such as the watt (J/s) and lux (cd/m2), or may just be expressed as combinations of base units, such as velocity (m/s) and acceleration (m/s2).The metric system was designed to have properties that make it easy to use and widely applicable, including units based on the natural world, decimal ratios, prefixes for multiples and sub-multiples, and a structure of base and derived units. It is a coherent system, which means that its units do not introduce conversion factors not already present in equations relating quantities.The metric system is extensible, and new derived units are defined as needed in fields such as radiology and chemistry. For example, the katal, a derived unit for catalytic activity equivalent to one mole per second (1 mol/s), was added in 1999. |
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