Split (1)

train · 253k rows

page_content stringlengths 51 3.15k
Transaction Processing System Real-time processing Transaction_processing_systems > Processing types > Real-time processing "Real time systems attempt to guarantee an appropriate response to a stimulus or request quickly enough to affect the conditions that caused the stimulus." Each transaction in realtime processing is unique; it is not part of a group of transactions.
Non-alcoholic fatty liver disease Fructose consumption Non-alcoholic_fatty_liver_disease > Pathophysiology > Fructose consumption Furthermore, high fructose consumption promotes fat accumulation in the liver by stimulating de novo lipogenesis in the liver and reducing the beta-oxidation of fat. Unlike the sugar glucose, the enzyme fructokinase rapidly metabolizes fructose. This leads to a decreased level of intracellular adenosine triphosphate (ATP). The decrease in ATP increases oxidative stress and impairments in proper protein synthesis and mitochondrial function in the liver.
Hex digit Summary Hex_digit In mathematics and computing, the hexadecimal (also base-16 or simply hex) numeral system is a positional numeral system that represents numbers using a radix (base) of sixteen. Unlike the decimal system representing numbers using ten symbols, hexadecimal uses sixteen distinct symbols, most often the symbols "0"–"9" to represent values 0 to 9, and "A"–"F" (or alternatively "a"–"f") to represent values from ten to fifteen. Software developers and system designers widely use hexadecimal numbers because they provide a human-friendly representation of binary-coded values. Each hexadecimal digit represents four bits (binary digits), also known as a nibble (or nybble).
Abstract interpretation Abstract interpretation of computer programs Abstract_interpretation > Abstract interpretation of computer programs In general, there is a compromise to be made between the precision of the analysis and its decidability (computability), or tractability (computational cost). In practice the abstractions that are defined are tailored to both the program properties one desires to analyze, and to the set of target programs. The first large scale automated analysis of computer programs with abstract interpretation was motivated by the accident that resulted in the destruction of the first flight of the Ariane 5 rocket in 1996.
Electrophilic aromatic substitution Summary Electrophilic_aromatic_substitution Electrophilic aromatic substitution is an organic reaction in which an atom that is attached to an aromatic system (usually hydrogen) is replaced by an electrophile. Some of the most important electrophilic aromatic substitutions are aromatic nitration, aromatic halogenation, aromatic sulfonation, alkylation and acylation Friedel–Crafts reaction.
Jinchao Xu Research Interests and Contributions Jinchao_Xu > Research Interests and Contributions In recent years, Xu has become interested in developing training algorithms for deep learning models and their applications, such as Alzheimer's disease, pathological image recognition, and pulse data analysis. He constructed the connections of ReLU deep neural networks and the classical linear finite element. Xu proposed a new idea for understanding ResNet models from the viewpoint of the multigrid method and also proposed iRDA training algorithms for the training process in CNN, which can achieve a sparse result in this context.
Oxygen–hemoglobin dissociation curve Summary Oxygen-hemoglobin_dissociation_curve The oxygen–hemoglobin dissociation curve, also called the oxyhemoglobin dissociation curve or oxygen dissociation curve (ODC), is a curve that plots the proportion of hemoglobin in its saturated (oxygen-laden) form on the vertical axis against the prevailing oxygen tension on the horizontal axis. This curve is an important tool for understanding how our blood carries and releases oxygen. Specifically, the oxyhemoglobin dissociation curve relates oxygen saturation (SO2) and partial pressure of oxygen in the blood (PO2), and is determined by what is called "hemoglobin affinity for oxygen"; that is, how readily hemoglobin acquires and releases oxygen molecules into the fluid that surrounds it.
Edsger W. Dijkstra Early years Edsger_W._Dijkstra > Life and works > Early years The point was that I was supposed to study theoretical physics at the University of Leiden simultaneously, and as I found the two activities harder and harder to combine, I had to make up my mind, either to stop programming and become a real, respectable theoretical physicist, or to carry my study of physics to a formal completion only, with a minimum of effort, and to become....., yes what? A programmer? But was that a respectable profession?
Receptivity (NMR) Summary Receptivity_(NMR) Other isotopes, for example 103Rh, are highly abundant but have low gyromagnetic ratios. Widely used NMR spectroscopies often focus on highly receptive elements: 1H, 19F, and 31P. == References ==
Australasian swamphen Life cycle Australasian_swamphen > Life cycle Nesting, breeding and rearing are as for the general species, see purple swamphen. In New Zealand they nest, typically well hidden in the middle of a clump of raupo, between August (end of winter) and March (start of autumn). Most eggs are laid between August and February with breeding reaching a peak in spring between September and December. New Zealand pūkeko are joint-nesters and multiple females will lay their eggs in the same nest. The recent development of a useful PCR-based genetic marker to determine the sex of pūkeko has revealed that there is no evidence of sex ratio bias in hatching-order. Patterns of growth, survivorship and adult dominance in this species is therefore attributed to hatching order rather than offspring sex
Inertia ellipsoid Angular kinetic energy constraint Poinsot's_ellipsoid > Angular kinetic energy constraint The law of conservation of energy implies that in the absence of energy dissipation or applied torques, the angular kinetic energy T {\displaystyle T\ } is conserved, so d T d t = 0 {\textstyle {\frac {dT}{dt}}=0} . The angular kinetic energy may be expressed in terms of the moment of inertia tensor I {\displaystyle \mathbf {I} } and the angular velocity vector ω {\displaystyle {\boldsymbol {\omega }}} T = 1 2 ω ⋅ I ⋅ ω = 1 2 I 1 ω 1 2 + 1 2 I 2 ω 2 2 + 1 2 I 3 ω 3 2 {\displaystyle T={\frac {1}{2}}{\boldsymbol {\omega }}\cdot \mathbf {I} \cdot {\boldsymbol {\omega }}={\frac {1}{2}}I_{1}\omega _{1}^{2}+{\frac {1}{2}}I_{2}\omega _{2}^{2}+{\frac {1}{2}}I_{3}\omega _{3}^{2}} where ω k {\displaystyle \omega _{k}\ } are the components of the angular velocity vector ω {\displaystyle {\boldsymbol {\omega }}} , and the I k {\displaystyle I_{k}\ } are the principal moments of inertia when both are in the body frame. Thus, the conservation of kinetic energy imposes a constraint on the three-dimensional angular velocity vector ω {\displaystyle {\boldsymbol {\omega }}} ; in the principal axis frame, it must lie on the ellipsoid defined by the above equation, called the inertia ellipsoid. The path traced out on this ellipsoid by the angular velocity vector ω {\displaystyle {\boldsymbol {\omega }}} is called the polhode (coined by Poinsot from Greek roots for "pole path") and is generally circular or taco-shaped.
Transistor tester Service type transistor testers Transistor_tester > Types of tester > Service type transistor testers These devices usually perform three types of checks: Forward-current gain, or beta of transistor. Base-to-collector leakage current with emitter open(ico) Short circuits from collector to emitter and base.Some service testers include a go/no-go feature, indicating a pass when a certain hfe is exceeded. These are useful, but fail some functional but low hfe transistors. Some also provide a means of identifying transistor elements, if these are unknown.
Monoidal category Properties and associated notions Free_strict_monoidal_category > Properties and associated notions Further, any (small) strict monoidal category can be seen as a monoid object in the category of categories Cat (equipped with the monoidal structure induced by the cartesian product). Monoidal functors are the functors between monoidal categories that preserve the tensor product and monoidal natural transformations are the natural transformations, between those functors, which are "compatible" with the tensor product. Every monoidal category can be seen as the category B(∗, ∗) of a bicategory B with only one object, denoted ∗. The concept of a category C enriched in a monoidal category M replaces the notion of a set of morphisms between pairs of objects in C with the notion of an M-object of morphisms between every two objects in C.
Groundwater flow equation Laplace equation (steady-state flow) Groundwater_flow_equation > Laplace equation (steady-state flow) If the aquifer has recharging boundary conditions a steady-state may be reached (or it may be used as an approximation in many cases), and the diffusion equation (above) simplifies to the Laplace equation. 0 = α ∇ 2 h {\displaystyle 0=\alpha \nabla ^{2}h} This equation states that hydraulic head is a harmonic function, and has many analogs in other fields. The Laplace equation can be solved using techniques, using similar assumptions stated above, but with the additional requirements of a steady-state flow field. A common method for solution of this equations in civil engineering and soil mechanics is to use the graphical technique of drawing flownets; where contour lines of hydraulic head and the stream function make a curvilinear grid, allowing complex geometries to be solved approximately. Steady-state flow to a pumping well (which never truly occurs, but is sometimes a useful approximation) is commonly called the Thiem solution.
Immune systems Gamma delta T cells Human_immune_system > Adaptive immune system > Cell mediated immunity > Gamma delta T cells Gamma delta T cells (γδ T cells) possess an alternative T-cell receptor (TCR) as opposed to CD4+ and CD8+ (αβ) T cells and share the characteristics of helper T cells, cytotoxic T cells and NK cells. The conditions that produce responses from γδ T cells are not fully understood. Like other 'unconventional' T cell subsets bearing invariant TCRs, such as CD1d-restricted natural killer T cells, γδ T cells straddle the border between innate and adaptive immunity.
Constant factor rule in differentiation Summary Sum_rule_in_differentiation This is a summary of differentiation rules, that is, rules for computing the derivative of a function in calculus.
Applications of capacitors Hazards and safety Filter_capacitor > Hazards and safety Proper containment, fusing, and preventive maintenance can help to minimize these hazards. High-voltage capacitors can benefit from a pre-charge to limit in-rush currents at power-up of high voltage direct current (HVDC) circuits. This will extend the life of the component and may mitigate high-voltage hazards.
Magnetic scalar potential Summary Magnetic_scalar_potential Magnetic scalar potential, ψ, is a quantity in classical electromagnetism analogous to electric potential. It is used to specify the magnetic H-field in cases when there are no free currents, in a manner analogous to using the electric potential to determine the electric field in electrostatics. One important use of ψ is to determine the magnetic field due to permanent magnets when their magnetization is known. The potential is valid in any region with zero current density, thus if currents are confined to wires or surfaces, piecemeal solutions can be stitched together to provide a description of the magnetic field at all points in space.
Induced cell cycle arrest Summary Induced_cell_cycle_arrest Induced cell cycle arrest is the use of a chemical or genetic manipulation to artificially halt progression through the cell cycle. Cellular processes like genome duplication and cell division stop. It can be temporary or permanent. It is an artificial activation of naturally occurring cell cycle checkpoints, induced by exogenous stimuli controlled by an experimenter.
Unifying theories in mathematics Historical perspective Unifying_theories_in_mathematics > Historical perspective The process of unification might be seen as helping to define what constitutes mathematics as a discipline. For example, mechanics and mathematical analysis were commonly combined into one subject during the 18th century, united by the differential equation concept; while algebra and geometry were considered largely distinct. Now we consider analysis, algebra, and geometry, but not mechanics, as parts of mathematics because they are primarily deductive formal sciences, while mechanics like physics must proceed from observation. There is no major loss of content, with analytical mechanics in the old sense now expressed in terms of symplectic topology, based on the newer theory of manifolds.
Ligand Common ligands Ligand_exchange > Common ligands The steric properties of some ligands are evaluated in terms of their cone angles. Beyond the classical Lewis bases and anions, all unsaturated molecules are also ligands, utilizing their pi electrons in forming the coordinate bond. Also, metals can bind to the σ bonds in for example silanes, hydrocarbons, and dihydrogen (see also: Agostic interaction). In complexes of non-innocent ligands, the ligand is bonded to metals via conventional bonds, but the ligand is also redox-active.
PP (complexity class) PP compared to other complexity classes Probabilistic_polynomial-time > PP compared to other complexity classes PP includes BPP, since probabilistic algorithms described in the definition of BPP form a subset of those in the definition of PP. PP also includes NP. To prove this, we show that the NP-complete satisfiability problem belongs to PP.
Bloom syndrome protein Interactions Bloom_syndrome_protein > Interactions Bloom syndrome protein has been shown to interact with:
GaCl3 Complexes GaCl3 > Complexes Gallium is the lightest member of Group 13 to have a full d shell, (gallium has the electronic configuration 3d10 4s2 4p1) below the valence electrons that could take part in d-π bonding with ligands. The low oxidation state of Ga in Ga(III)Cl3, along with the low electronegativity and high polarisability, allow GaCl3 to behave as a "soft acid" in terms of the HSAB theory. The strength of the bonds between gallium halides and ligands have been extensively studied.
Inclusive Design Examples of inclusive design Inclusive_Design > Examples of inclusive design There are numerous examples of inclusive design that apply to interfaces and technology, consumer products, and infrastructure.
Markovian property History Transition_density > History Markov later used Markov chains to study the distribution of vowels in Eugene Onegin, written by Alexander Pushkin, and proved a central limit theorem for such chains.In 1912 Henri Poincaré studied Markov chains on finite groups with an aim to study card shuffling. Other early uses of Markov chains include a diffusion model, introduced by Paul and Tatyana Ehrenfest in 1907, and a branching process, introduced by Francis Galton and Henry William Watson in 1873, preceding the work of Markov. After the work of Galton and Watson, it was later revealed that their branching process had been independently discovered and studied around three decades earlier by Irénée-Jules Bienaymé.
Chelate effect Chelate effect Chelation > Chelate effect The square brackets indicate concentration, and the subscripts to the stability constants, β, indicate the stoichiometry of the complex. When the analytical concentration of methylamine is twice that of ethylenediamine and the concentration of copper is the same in both reactions, the concentration is much higher than the concentration because β11 ≫ β12. An equilibrium constant, K, is related to the standard Gibbs free energy, Δ G ⊖ {\displaystyle \Delta G^{\ominus }} by Δ G ⊖ = − R T ln ⁡ K = Δ H ⊖ − T Δ S ⊖ {\displaystyle \Delta G^{\ominus }=-RT\ln K=\Delta H^{\ominus }-T\Delta S^{\ominus }} where R is the gas constant and T is the temperature in kelvins.
Thermoeconomics Thermodynamics Biophysical_economics > Thermodynamics "Rien ne se perd, rien ne se crée, tout se transforme" "Nothing is lost, nothing is created, everything is transformed." -Antoine Lavoisier, one of the fathers of chemistryThermoeconomists maintain that human economic systems can be modeled as thermodynamic systems. Thermoeconomists argue that economic systems always involve matter, energy, entropy, and information. Then, based on this premise, theoretical economic analogs of the first and second laws of thermodynamics are developed.
Antitubercular agent Treatment of MDR-TB Antituberculous_drug > Drug-resistance > Treatment of MDR-TB Mortality and morbidity in patients treated in non-specialist centres is significantly elevated compared to those patients treated in specialist centres. In addition to the obvious risks (e.g., known exposure to a patient with MDR-TB), risk factors for MDR-TB include male sex, HIV infection, previous incarceration, failed TB treatment, failure to respond to standard TB treatment, and relapse following standard TB treatment. A large proportion of people with MDR-TB are unable to access treatment due to what Paul Farmer describes as an "Outcome Gap".
HTML table Tables HTML_element > Document body elements > Tables The format of HTML Tables was proposed in the HTML 3.0 Drafts and the later RFC 1942 HTML Tables. They were inspired by the CALS Table Model. Some elements in these proposals were included in HTML 3.2; the present form of HTML Tables was standardized in HTML 4. (Many of the elements used within tables are neither block nor inline elements.)
Lisp programming language Summary Lisp_programming_language It quickly became a favored programming language for artificial intelligence (AI) research. As one of the earliest programming languages, Lisp pioneered many ideas in computer science, including tree data structures, automatic storage management, dynamic typing, conditionals, higher-order functions, recursion, the self-hosting compiler, and the read–eval–print loop.The name LISP derives from "LISt Processor". Linked lists are one of Lisp's major data structures, and Lisp source code is made of lists.
Basal nuclei Eye movements Basal_nuclei > Function > Eye movements One intensively studied function of the basal ganglia is its role in controlling eye movements. Eye movement is influenced by an extensive network of brain regions that converges on a midbrain area called the superior colliculus (SC). The SC is a layered structure whose layers form two-dimensional retinotopic maps of visual space. A "bump" of neural activity in the deep layers of the SC drives an eye movement directed toward the corresponding point in space.
Small nucleolar RNA Me28S-Gm3255 Summary Small_nucleolar_RNA_Me28S-Gm3255 In molecular biology, Small nucleolar RNA Me28S-Gm3255 is a non-coding RNA (ncRNA) molecule which functions in the modification of other small nuclear RNAs (snRNAs). This type of modifying RNA is usually located in the nucleolus of the eukaryotic cell which is a major site of snRNA biogenesis. It is known as a small nucleolar RNA (snoRNA) and also often referred to as a guide RNA.
Copenhagen interpretation Principles Copenhagen_interpretation_of_quantum_mechanics > Principles Per the above point, the device used to observe a system must be described in classical language, while the system under observation is treated in quantum terms. This is a particularly subtle issue for which Bohr and Heisenberg came to differing conclusions. According to Heisenberg, the boundary between classical and quantum can be shifted in either direction at the observer's discretion.
Mersenne primes Theorems about Mersenne numbers Mersenne_numbers > Theorems about Mersenne numbers For example, 25 − 1 = 31 is prime, and 31 = 1 + 3 × (2 × 5). A composite example is 211 − 1 = 23 × 89, where 23 = 1 + (2 × 11) and 89 = 1 + 4 × (2 × 11). Proof: By Fermat's little theorem, q is a factor of 2q−1 − 1.
Solar pressure Compression in a uniform radiation field Radiation_Pressure > Theory > Compression in a uniform radiation field In general, the pressure of electromagnetic waves can be obtained from the vanishing of the trace of the electromagnetic stress tensor: since this trace equals 3P − u, we get where u is the radiation energy per unit volume. This can also be shown in the specific case of the pressure exerted on surfaces of a body in thermal equilibrium with its surroundings, at a temperature T: the body will be surrounded by a uniform radiation field described by the Planck black-body radiation law and will experience a compressive pressure due to that impinging radiation, its reflection, and its own black-body emission. From that it can be shown that the resulting pressure is equal to one third of the total radiant energy per unit volume in the surrounding space.By using Stefan–Boltzmann law, this can be expressed as where σ {\displaystyle \sigma } is the Stefan–Boltzmann constant.
Hodograph Meteorology Hodograph_transformation > Applications > Meteorology In meteorology, hodographs are used to plot winds from soundings of the Earth's atmosphere. It is a polar diagram where wind direction is indicated by the angle from the center axis and its strength by the distance from the center. In the figure to the right, at the bottom one finds values of wind at 4 heights above ground. They are plotted by the vectors V → 0 {\displaystyle {\vec {V}}_{0}} to V → 4 {\displaystyle {\vec {V}}_{4}} .
Mechanical integrity Scope Mechanical_integrity > Scope These are used to build suitable inspection and condition monitoring forward strategies. The monitoring may include physical (pipes/vessels) and nonphysical systems (Management legal obligations). This diversity will depend upon the requirements of the task at hand. Integrity Engineers also oversee or carry out Integrity Engineering Audit(s) to ensure legal compliance with company, national and international standards and ensure quality assurance within the process that meets good engineering standards.
NADPH oxidase Reaction NADPH_oxidase > Reaction NADPH oxidase catalyzes the production of a superoxide free radical by transferring one electron to oxygen from NADPH.NADPH + 2O2 ↔ NADP+ + 2O−2 + H+
Rare gas Compounds Rare_gas > Chemical properties > Compounds This model, first proposed in 1951, considers bonding of three collinear atoms. For example, bonding in XeF2 is described by a set of three molecular orbitals (MOs) derived from p-orbitals on each atom. Bonding results from the combination of a filled p-orbital from Xe with one half-filled p-orbital from each F atom, resulting in a filled bonding orbital, a filled non-bonding orbital, and an empty antibonding orbital.
Eyeblink conditioning CS-US contingency Eyeblink_conditioning > CS-US contingency Other stimulus contingencies include backward conditioning, in which US comes before CS, and simultaneous conditioning, in which CS and US are presented at the same time. In any case, the time between CS onset and US onset is the interstimulus interval (ISI). Animals are usually trained with a shorter ISI than humans, which can make interspecies comparisons difficult.
Groenewold's theorem Single particle systems Canonical_quantisation > First quantization > Single particle systems For example, the energy is read off by the Hamiltonian operator H ^ {\displaystyle {\hat {H}}} acting on a state \| ψ n ⟩ {\displaystyle \|\psi _{n}\rangle } , yielding where En is the characteristic energy associated to this \| ψ n ⟩ {\displaystyle \|\psi _{n}\rangle } eigenstate. Any state could be represented as a linear combination of eigenstates of energy; for example, where an are constant coefficients. As in classical mechanics, all dynamical operators can be represented by functions of the position and momentum ones, X ^ {\displaystyle {\hat {X}}} and P ^ {\displaystyle {\hat {P}}} , respectively.
Competitive analysis (online algorithm) Summary Competitive_ratio For example, sorting an array of elements varies in difficulty depending on the initial order. Such data-dependent algorithms are analysed for average-case and worst-case data. Competitive analysis is a way of doing worst case analysis for on-line and randomized algorithms, which are typically data dependent.
Polarization controller Summary Polarization_controller A polarization controller is an optical device which allows one to modify the polarization state of light.
Gamma function Integration problems Euler_Gamma_Function > Applications > Integration problems It is of course frequently useful to take limits of integration other than 0 and ∞ to describe the cumulation of a finite process, in which case the ordinary gamma function is no longer a solution; the solution is then called an incomplete gamma function. (The ordinary gamma function, obtained by integrating across the entire positive real line, is sometimes called the complete gamma function for contrast.) An important category of exponentially decaying functions is that of Gaussian functions and integrals thereof, such as the error function.
Frozen orbit Background and motivation Frozen_orbit > Background and motivation For sun-synchronous spacecraft, intentional shifting of the orbit plane (called "precession") can be used for the benefit of the mission. For these missions, a near-circular orbit with an altitude of 600–900 km is used. An appropriate inclination (97.8-99.0 degrees) is selected so that the precession of the orbital plane is equal to the rate of movement of the Earth around the sun, about 1 degree per day.
Multifocal diffractive lens Principle of operation Multifocal_diffractive_lens > Principle of operation An incident laser beam is deflected by grooved diffraction pattern into axial diffraction orders along its optical axis. The foci appear around the far field position. With an additional focusing lens, foci from multifocal lens will appear at certain distances from the focal point of the lens.
Basket options Summary Basket_option A basket option is a financial derivative, more specifically an exotic option, whose underlying is a weighted sum or average of different assets that have been grouped together in a basket. A basket option is similar to an index option, where a number of stocks have been grouped together in an index and the option is based on the price of the index, but differs in that the members and weightings of an index can change over time while those in a basket option do not.Unlike a rainbow option which considers a group of assets but ultimately pays out on the level of one, a basket option is written on a basket of underlying assets but will pay out on a weighted average gain of the basket as a whole.Like rainbow options basket options are most commonly written on a basket of equity indices, though they are frequently written on a basket of individual equities as well. For example, a call option could be written on a basket of ten healthcare stocks, where the basket was composed of ten stocks in weighted proportions. The strike price Xbasket is usually set at the current value of the basket (at-the-money), and the payoff profile will be max(Sbasket − Xbasket, 0) where Sbasket is a weighted average of n asset prices at maturity, and each weight represents the percentage of total investment in that asset.
Story arc Dramatic structure and purpose Story_arc > Dramatic structure and purpose The purpose of a story arc is to move a character or a situation from one state to another, in other words, to effect change. This change or transformation often takes the form of either a tragic fall from grace or a reversal of that pattern. One common form in which this reversal is found is a character going from a situation of weakness to one of strength. For example, a poor woman goes on adventures and in the end makes a fortune for herself, or a lonely man falls in love and marries.
Aliquot part Further notions and facts Aliquot_part > Further notions and facts A number that does not evenly divide n {\displaystyle n} but leaves a remainder is sometimes called an aliquant part of n {\displaystyle n} . An integer n > 1 {\displaystyle n>1} whose only proper divisor is 1 is called a prime number. Equivalently, a prime number is a positive integer that has exactly two positive factors: 1 and itself.
Power stealing Thermoelectrics Energy_harvesting_devices > Energy sources > Thermoelectrics The semiconductors are connected electrically in series and thermally in parallel. Miniature thermocouples have been developed that convert body heat into electricity and generate 40 μ W at 3 V with a 5-degree temperature gradient, while on the other end of the scale, large thermocouples are used in nuclear RTG batteries.
Acid mantle Summary Acid_mantle However the pH of the skin’s acid mantle is a broad range that depends on the condition of the skin and other estimates deem the range to be between 4.5 and 6.5 as slightly acidic. More recent research has challenged the proposed ranges. When healthy human skin has not had contact with skin products or water for extended periods it has been found to naturally return to acidity levels below that of 5.0.
Periodic comet Summary Periodic_comet Periodic comets (also known as short-period comets) are comets with orbital periods of less than 200 years or that have been observed during more than a single perihelion passage (e.g. 153P/Ikeya–Zhang). "Periodic comet" is also sometimes used to mean any comet with a periodic orbit, even if greater than 200 years. Periodic comets receive a permanent number prefix usually after the second perihelion passage, which is why there are a number of unnumbered periodic comets, such as P/2005 T5 (Broughton).
Glossary of aerospace engineering M Glossary_of_aerospace_engineering > M It is sometimes referred to as Lorentz Force Accelerator (LFA) or (mostly in Japan) MPD arcjet. Mass – is both a property of a physical body and a measure of its resistance to acceleration (rate of change of velocity with respect to time) when a net force is applied.
Turing Test The Alan Turing Year, and Turing100 in 2012 Imitation_game > Conferences > The Alan Turing Year, and Turing100 in 2012 Throughout 2012, a number of major events took place to celebrate Turing's life and scientific impact. The Turing100 group supported these events and also organised a special Turing test event in Bletchley Park on 23 June 2012 to celebrate the 100th anniversary of Turing's birth.
Control charts Chart usage Control_charts > Chart details > Chart usage This makes the control limits very important decision aids. The control limits provide information about the process behavior and have no intrinsic relationship to any specification targets or engineering tolerance. In practice, the process mean (and hence the centre line) may not coincide with the specified value (or target) of the quality characteristic because the process design simply cannot deliver the process characteristic at the desired level.
Electrolytic capacitor Lifetime Electrolytic_capacitors > Operational characteristics > Lifetime The lifetime, service life, load life or useful life of electrolytic capacitors is a special characteristic of non-solid aluminum electrolytic capacitors, whose liquid electrolyte can evaporate over time. Lowering the electrolyte level affects the electrical parameters of the capacitors. The capacitance decreases and the impedance and ESR increase with decreasing amounts of electrolyte. This very slow electrolyte drying-out depends on the temperature, the applied ripple current load, and the applied voltage.
Pituitary apoplexy Treatment Pituitary_apoplexy > Treatment The first priority in suspected or confirmed pituitary apoplexy is stabilization of the circulatory system. Cortisol deficiency can cause severe low blood pressure. Depending on the severity of the illness, admission to a high dependency unit (HDU) may be required.Treatment for acute adrenal insufficiency requires the administration of intravenous saline or dextrose solution; volumes of over two liters may be required in an adult. This is followed by the administration of hydrocortisone, which is pharmaceutical grade cortisol, intravenously or into a muscle.
Tree-depth Depth of trees and relation to treewidth Tree-depth > Depth of trees and relation to treewidth The same technique, applied to a tree decomposition of a graph, shows that, if the treewidth of an n {\displaystyle n} -vertex graph G {\displaystyle G} is t {\displaystyle t} , then the tree-depth of G {\displaystyle G} is O ( t log ⁡ n ) {\displaystyle O(t\log n)} . Since outerplanar graphs, series–parallel graphs, and Halin graphs all have bounded treewidth, they all also have at most logarithmic tree-depth. The typical graphs with large treedepth and small treewidth are the perfect binary trees and the paths. Precisely, there is a constant C {\displaystyle C} with the following property: if a graph has treedepth at least C k 5 log 2 ⁡ k {\displaystyle Ck^{5}\log ^{2}k} and treewidth less than k {\displaystyle k} then it contains a perfect binary tree with height k {\displaystyle k} or a path of length 2 k {\displaystyle 2^{k}} as a minor.In the other direction, the treewidth of a graph is at most equal to its tree-depth. More precisely, the treewidth is at most the pathwidth, which is at most one less than the tree-depth.
Vibration fatigue Vibration-fatigue methods Vibration_fatigue > Vibration-fatigue-life estimation > Vibration-fatigue methods The formulas for calculating such estimate are empirical (with very few exceptions) and are based on numerous simulations of random processes with known PSD. As a consequence, the accuracy of those methods varies, depending on analyzed response spectra, material parameters and the method itself - some are more accurate than others.The most commonly used method is the one developed by T. Dirlik in 1985. Recent research on frequency-domain methods of fatigue-life estimation compared well established methods and also recent ones; conclusion showed that the methods by Zhao and Baker, developed in 1992 and by Benasciutti and Tovo, developed in 2004 are also very suitable for vibration-fatigue analysis.
NTFS links Summary NTFS_junction_point The NTFS file system defines various ways to redirect files and folders, e.g., to make a file point to another file or its contents without making a copy of it. The object being pointed to is called the target. Such file is called a hard or symbolic link depending on a way it's stored on the filesystem.
Bra size Consumer measurement methods Bra_size > Consumer measurement methods Bra retailers recommend several methods for measuring band and cup size. These are based on two primary methods, either under the bust or over the bust, and sometimes both. Calculating the correct bra band size is complicated by a variety of factors. The American National Standards Institute states that while a voluntary consensus of sizes exists, there is much confusion to the 'true' size of clothing.
Ozone depletion and climate change Policy approach Ozone_depletion_and_climate_change > Policy approach There are both links and major differences between ozone depletion and global warming and the way the two challenges have been handled. While in the case of atmospheric ozone depletion, in a situation of high uncertainty and against strong resistance, climate change regulation attempts at the international level such as the Kyoto Protocol have failed to reduce global emissions. The Vienna Convention for the Protection of the Ozone Layer and the Montreal Protocol were both originally signed by only some member states of the United Nations (43 nations in the case of the Montreal Protocol in 1986) while Kyoto attempted to create a worldwide agreement from scratch. Expert consensus concerning CFCs in the form of the Scientific Assessment of Ozone Depletion was reached long after the first regulatory steps were taken, and as of 29 December 2012, all countries in the United Nations plus the Cook Islands, the Holy See, Niue and the supranational European Union had ratified the original Montreal Protocol.
Fermat's theorem on sums of two squares Algorithm Fermat's_theorem_on_sums_of_two_squares > Algorithm The number of needed tests is of the order of p = exp ⁡ ( log ⁡ p 2 ) , {\displaystyle {\sqrt {p}}=\exp \left({\frac {\log p}{2}}\right),} and thus exponential in the input size. So the computational complexity of this algorithm is exponential. An algorithm with a polynomial complexity has been described by Stan Wagon in 1990, based on work by Serret and Hermite (1848), and Cornacchia (1908).
Antiprotonic hydrogen Summary Protonium Protonium (symbol: Pn), also known as antiprotonic hydrogen, is a type of exotic atom in which a proton (symbol: p) and an antiproton (symbol: p) orbit each other. Since protonium is a bound system of a particle and its corresponding antiparticle, it is an example of a type of exotic atom called an onium. Protonium has a mean lifetime of approximately 1.0 μs and a binding energy of −0.75 keV.Like all onia, protonium is a boson with all quantum numbers (baryon number, flavour quantum numbers, etc.) and electrical charge equal to 0.
Molecular vibrations Internal coordinates Vibrational_transition > Vibrational coordinates > Internal coordinates Note that the H–C–C angles cannot be used as internal coordinates as well as the H-C-H angle because the angles at each carbon atom cannot all increase at the same time. Note that these coordinates do not correspond to normal modes (see #Normal coordinates). In other words, they do not correspond to particular frequencies or vibrational transitions.
Split attention effect A visual example of split attention Split_attention_effect > A visual example of split attention The figure on the left side of the image produces the split-attention effect, while the figure on the right enhances learning because it guides the learner's attention through the worked example. Unincorporated visual displays of information, such as the image above, can be distracting and confusing for the user, aside from producing the split-attention effect. The split-attention effect is an important form of extraneous cognitive load that instructional material designers should avoid.
Nuclear magnetic resonance spectroscopy of stereoisomers Summary NMR_spectroscopy_of_stereoisomers Mosher's acid contains a -CF3 group, so if the adduct has no other fluorine atoms, the 19F NMR of a racemic mixture shows just two peaks, one for each stereoisomer. As with NMR spectroscopy in general, good resolution requires a high signal-to-noise ratio, clear separation between peaks for each stereoisomer, and narrow line width for each peak. Chiral lanthanide shift reagents cause a clear separation of chemical shift, but they must be used in low concentrations to avoid line broadening.
Legendre transform Analytical mechanics Legendre_transform > Applications > Analytical mechanics A Legendre transform is used in classical mechanics to derive the Hamiltonian formulation from the Lagrangian formulation, and conversely. A typical Lagrangian has the form where ( v , q ) {\displaystyle (v,q)} are coordinates on Rn × Rn, M is a positive real matrix, and For every q fixed, L ( v , q ) {\displaystyle L(v,q)} is a convex function of v {\displaystyle v} , while V ( q ) {\displaystyle V(q)} plays the role of a constant. Hence the Legendre transform of L ( v , q ) {\displaystyle L(v,q)} as a function of v {\displaystyle v} is the Hamiltonian function, In a more general setting, ( v , q ) {\displaystyle (v,q)} are local coordinates on the tangent bundle T M {\displaystyle T{\mathcal {M}}} of a manifold M {\displaystyle {\mathcal {M}}} .
Inner planets Orbits Outer_planet > Structure and composition > Orbits Kepler's laws only account for the influence of the Sun's gravity upon an orbiting body, not the gravitational pulls of different bodies upon each other. On a human time scale, these additional perturbations can be accounted for using numerical models,: 9-6 but the planetary system can change chaotically over billions of years.The angular momentum of the Solar System is a measure of the total amount of orbital and rotational momentum possessed by all its moving components. Although the Sun dominates the system by mass, it accounts for only about 2% of the angular momentum. The planets, dominated by Jupiter, account for most of the rest of the angular momentum due to the combination of their mass, orbit, and distance from the Sun, with a possibly significant contribution from comets.
Energy-dispersive X-ray diffraction Summary Energy-dispersive_X-ray_diffraction Energy-dispersive X-ray diffraction (EDXRD) is an analytical technique for characterizing materials. It differs from conventional X-ray diffraction by using polychromatic photons as the source and is usually operated at a fixed angle. With no need for a goniometer, EDXRD is able to collect full diffraction patterns very quickly. EDXRD is almost exclusively used with synchrotron radiation which allows for measurement within real engineering materials.
Spanner (distributed database technology) Features Spanner_(database) > Features Replication is synchronous and strongly consistent. Reads are strongly consistent and data is versioned to allow for stale reads: clients can read previous versions of data, subject to garbage collection windows. Supports a native SQL interface for reading and writing data.
C3H5ClO Summary C3H5ClO The molecular formula C3H5ClO (molar mass: 92.52 g/mol, exact mass: 92.0029 u) may refer to: Chloroacetone, a colourless liquid with a pungent odour Epichlorohydrin, an organochlorine compound and an epoxide
Viscoelasticity Viscoelastic creep Viscoelasticity > Viscoelastic creep If, on the other hand, it is a viscoelastic solid, it may or may not fail depending on the applied stress versus the material's ultimate resistance. When the stress is maintained for a shorter time period, the material undergoes an initial strain until a time t 1 {\displaystyle t_{1}} , after which the strain immediately decreases (discontinuity) then gradually decreases at times t > t 1 {\displaystyle t>t_{1}} to a residual strain. Viscoelastic creep data can be presented by plotting the creep modulus (constant applied stress divided by total strain at a particular time) as a function of time.
Data-flow diagram History Data-flow_diagram > History The DFD notation draws on graph theory, originally used in operational research to model workflow in organizations. DFD originated from the activity diagram used in the structured analysis and design technique methodology at the end of the 1970s. DFD popularizers include Edward Yourdon, Larry Constantine, Tom DeMarco, Chris Gane and Trish Sarson.Data-flow diagrams (DFD) quickly became a popular way to visualize the major steps and data involved in software-system processes. DFDs were usually used to show data flow in a computer system, although they could in theory be applied to business process modeling. DFDs were useful to document the major data flows or to explore a new high-level design in terms of data flow.
Weak reference Uses Weak_reference > Uses Weak references have a number of common uses. When using reference counting garbage collection, weak references can break reference cycles, by using a weak reference for a link in the cycle. When one has an associative array (mapping, hash map) whose keys are (references to) objects, for example to hold auxiliary data about objects, using weak references for the keys avoids keeping the objects alive just because of their use as keys. When one has an object where other objects are registered, such as in the observer pattern (particularly in event handling), if a strong reference is kept, objects must be explicitly unregistered, otherwise a memory leak occurs (the lapsed listener problem), while a weak reference removes the need to unregister.
North Atlantic Deep Water Formation and sources North_Atlantic_Deep_Water > Formation and sources Eddies of cold less saline ULSW have similar densities of warmer saltier water and flow along the DWBC, but maintain their high CFCs. The ULSW eddies erode rapidly as they mix laterally with this warmer saltier water.The lower waters mass of NADW form from overflow of the Greenland-Iceland-Scotland Ridge. They are Iceland-Scotland Overflow Water (ISOW) and Denmark Strait Overflow Water (DSOW).
Run-time algorithm specialization Specialization with compilation Run-time_algorithm_specialisation > Specialization with compilation In C or C++ we can use a switch statement to associate some actions with different instruction tags. Modern compilers usually compile a switch statement with integer labels from a narrow range rather efficiently by storing the address of the statement corresponding to a value i {\displaystyle i} in the i {\displaystyle i} -th cell of a special array. One can exploit this by taking values for instruction tags from a small interval of integers.
Planetary habitability in the Solar System Earth Planetary_habitability_in_the_Solar_System > Earth The atmosphere of Earth also plays an important role. The ozone layer protects the planet from the harmful radiations from the sun, and free oxygen is abundant enough for the breathing needs of terrestrial life. Earth's magnetosphere, generated by its active core, is also important for the long-term habitability of Earth, as it prevents the solar winds from stripping the atmosphere out of the planet.
C Sharp language Portability C_Sharp_language > Distinguishing features > Portability By design, C# is the programming language that most directly reflects the underlying Common Language Infrastructure (CLI). Most of its intrinsic types correspond to value-types implemented by the CLI framework. However, the language specification does not state the code generation requirements of the compiler: that is, it does not state that a C# compiler must target a Common Language Runtime, or generate Common Intermediate Language (CIL), or generate any other specific format. Theoretically, a C# compiler could generate machine code like traditional compilers of C++ or Fortran.
Cosocle Summary Cosocle In mathematics, the term cosocle (socle meaning pedestal in French) has several related meanings. In group theory, a cosocle of a group G, denoted by Cosoc(G), is the intersection of all maximal normal subgroups of G. If G is a quasisimple group, then Cosoc(G) = Z(G).In the context of Lie algebras, a cosocle of a symmetric Lie algebra is the eigenspace of its structural automorphism that corresponds to the eigenvalue +1. (A symmetric Lie algebra decomposes into the direct sum of its socle and cosocle. )In the context of module theory, the cosocle of a module over a ring R is defined to be the maximal semisimple quotient of the module.
Lawn mowers Gasoline (petrol) Lawn_mowing > Types > By energy source > Gasoline (petrol) The engines usually have a carburetor and require a manual pull crank to start them, although an electric starter is offered on some models, particularly large riding and commercial mowers. Some mowers have a throttle control on the handlebar with which the operator can adjust the engine speed. Other mowers have a fixed, pre-set engine speed.
Linnett Double-Quartet Theory Example: excited states of acetylene Linnett_Double-Quartet_Theory > Theoretical description of excited states > Example: excited states of acetylene Most strikingly, the molecule changes its geometry upon excitation, going from a simple linear symmetry to a trans-bent structure. This is in excellent agreement with both the landmark results of Ingold and King, which were the first demonstration of an excited state having a qualitatively different geometry than the ground state, and the results from molecular orbital theory methods. Thus, this example illustrates that LDQ theory can be a powerful tool for understanding the geometric rearrangements that occur when excited states are formed.
Audio crossover capacitor Passive Audio_crossover > Classification > Classification based on components > Passive A passive crossover splits up an audio signal after it is amplified by a single power amplifier, so that the amplified signal can be sent to two or more driver types, each of which cover different frequency ranges. These crossover are made entirely of passive components and circuitry; the term "passive" means that no additional power source is needed for the circuitry. A passive crossover just needs to be connected by wiring to the power amplifier signal. Passive crossovers are usually arranged in a Cauer topology to achieve a Butterworth filter effect.
Dental brace Fitting procedure Dental_Braces > Fitting procedure Directly bonded molar tubes are associated with a higher failure rate when compared to molar bands cemented with glass ionomer cement. Failure of orthodontic brackets, bonded tubes or bands will increase the overall treatment time for the patient. There is evidence suggesting that there is less enamel decalcification associated with molar bands cemented with glass ionomer cement compared with orthodontic tubes directly cemented to molars using a light cured adhesive.
Fundamental physical constants External articles Dimensionless_physical_constant > External articles S2CID 113017. Olive, Keith A.; Pospelov, Maxim; Qian, Yong-Zhong; Coc, Alain; Cassé, Michel; Vangioni-Flam, Elisabeth (2002-08-23). "Constraints on the variations of the fundamental couplings".
Node graph architecture Visual Programming Debate Node_graph_architecture > Visual Programming Debate Node graphs are a subset of the broader class of visual programming languages. Node graphs allow you to design programs in a visual and structured way instead of through the authoring of source code. In the film and video game industries node graphs are synonymous with visual programming. There is currently some debate on the power, abstraction, and need of node graphs and visual programming languages.
Painlevé paradox Physical realizations Painlevé_paradox > Physical realizations A common demonstration of the paradox is the "bouncing" of chalk when forced to slide across a blackboard. Since the Painlevé paradoxes are based on a mechanical model of Coulomb friction, where the calculated friction force can have multiple values when the contact point has no tangential velocity, this is a simplified model of contact. It does, nevertheless, encapsulate the main dynamical effects of friction, such as sticking and slipping zones. In addition to this simple example, more complex realizations of Painlevé paradoxes have been demonstrated. == References ==
Concurrent constraint logic programming Description Concurrent_constraint_logic_programming > Description A second effect of the difference between the non-concurrent and the concurrent version is that concurrent constraint logic programming is specifically designed to allow processes to run without terminating. Non-terminating processes are common in general in concurrent processing; the concurrent version of constraint logic programming implements them by not using the condition of failure: if no clause is applicable for rewriting a goal, the process evaluating this goal stops instead of making the whole evaluation fail like in non-concurrent constraint logic programming. As a result, the process evaluating a goal may be stopped because no clause is available to proceed, but at the same time the other processes keep running.
Lowell Schoenfeld Contributions Lowell_Schoenfeld > Contributions Schoenfeld is known for obtaining the following results in 1976, assuming the Riemann hypothesis: \| π ( x ) − l i ( x ) \| ≤ x ln ⁡ x 8 π {\displaystyle \|\pi (x)-{\rm {li}}(x)\|\leq {\frac {{\sqrt {x}}\,\ln x}{8\pi }}} for all x ≥ 2657, based on the prime-counting function π(x) and the logarithmic integral function li(x), and \| ψ ( x ) − x \| ≤ x ln 2 ⁡ x 8 π {\displaystyle \|\psi (x)-x\|\leq {\frac {{\sqrt {x}}\,\ln ^{2}x}{8\pi }}} for all x ≥ 73.2, based on the second Chebyshev function ψ(x).
Francoise Baylis Select research publications Francoise_Baylis > Select research publications Journal of Medical Ethics. 33 (12): 726–731. doi:10.1136/jme.2007.022129.
Chemical symbol Daltonian symbols Atomic_symbol > Symbols and names not currently used > Daltonian symbols The following symbols were employed by John Dalton in the early 1800s as the periodic table of elements was being formulated. Not included in this list are substances now known to be compounds, such as certain rare-earth mineral blends. Modern alphabetic notation was introduced in 1814 by Jöns Jakob Berzelius; its precursor can be seen in Dalton's circled letters for the metals, especially in his augmented table from 1810. A trace of Dalton's conventions also survives in ball-and-stick models of molecules, where balls for carbon are black and for oxygen red.
Pointer jumping List ranking Pointer_jumping > List ranking It is assumed, as in common in the PRAM model of computation, that memory access are performed in lock-step, so that each n.next.next memory fetch is performed before each n.next memory store; otherwise, processors may clobber each other's data, producing inconsistencies. : 694 The following diagram follows how the parallel list ranking algorithm uses pointer jumping for a linked list with 11 elements. As the algorithm describes, the first iteration starts initialized with all ranks set to 1 except those with a null pointer for next.
Direct visual feedback Summary Direct_visual_feedback Instead of using technically advanced measuring instruments for feedback, DVF relies on the human eye. One method that has been used to test DVF is by placing a laser beam on the hand and connecting it to a monitor, when the trainee raises his arm from waist height to shoulder height he is focused on the external reference showing exactly what path the arm took from point A(waist height) to point B(shoulder height). Studies have shown that not only is a higher level of performance often achieved faster with an external rather than an internal attention focus, but the skill is retained better.
Quantum finite automata Informal description Quantum_finite_automaton > Informal description Another generalization that should be immediately apparent is to use a stochastic matrix for the transition matrices, and a probability vector for the state; this gives a probabilistic finite automaton. The entries in the state vector must be real numbers, positive, and sum to one, in order for the state vector to be interpreted as a probability. The transition matrices must preserve this property: this is why they must be stochastic.
Mir-96 microRNA Summary Mir-96_microRNA Heterozygous mice and humans progressively lose the ability to hear. Five genes, of 132 predicted targets, have been experimentally validated as targets of miR-96: Aqp5, Celsr2, Myrip, Odf2 and Ryk.Microarray analysis of 4-day old wildtype and mutant mice showed that in the 3′ UTR of upregulated genes, there was a significant enrichment in heptamers complementary to miR-96, implying that miR-96 normally affects a wide range of target genes, and that the mutation results in a loss of normal targets. Among the downregulated genes, there is a significant enrichment in heptamers complementary to the mutant miR-96, so the mutant miR-96 has gained novel targets. Among the downregulated genes were five of particular interest; Ocm, Pitpnm1, Prestin, Ptprq and Gfi1, all of which are strongly and specifically expressed in hair cells. Mice mutant for the latter three exhibit deafness and hair cell degeneration.
Sintering Mechanical equilibrium Pressureless_sintering > Densification, vitrification and grain growth > Grain growth > Mechanical equilibrium As smaller particles tend to have a higher radius of curvature and this results in smaller grains losing atoms to larger grains and shrinking. This is a process called Ostwald ripening. Large grains grow at the expense of small grains. Grain growth in a simple model is found to follow: Here G is final average grain size, G0 is the initial average grain size, t is time, m is a factor between 2 and 4, and K is a factor given by: Here Q is the molar activation energy, R is the ideal gas constant, T is absolute temperature, and K0 is a material dependent factor. In most materials the sintered grain size is proportion to the inverse square root of the fractional porosity, implying that pores are the most effective retardant for grain growth during sintering.
Tension-type headache Stress Tension_headaches > Mechanism > Stress In the literature, stress is mentioned as a factor and may be implicated via the adrenal axis. This ultimately results in downstream activation of NMDA receptor activation, NFκB activation, and upregulation of iNOS with subsequent production of NO leading to pain as described above.
Group 1 element Atomic and ionic radii Alkaline_metal > Periodic trends > Atomic and ionic radii The atomic radii of the alkali metals increase going down the group. Because of the shielding effect, when an atom has more than one electron shell, each electron feels electric repulsion from the other electrons as well as electric attraction from the nucleus. In the alkali metals, the outermost electron only feels a net charge of +1, as some of the nuclear charge (which is equal to the atomic number) is cancelled by the inner electrons; the number of inner electrons of an alkali metal is always one less than the nuclear charge.
John Edensor Littlewood Work John_Edensor_Littlewood > Work Most of Littlewood's work was in the field of mathematical analysis. He began research under the supervision of Ernest William Barnes, who suggested that he attempt to prove the Riemann hypothesis: Littlewood showed that if the Riemann hypothesis is true, then the prime number theorem follows and obtained the error term. This work won him his Trinity fellowship. However, the link between the Riemann hypothesis and the prime number theorem had been known before in Continental Europe, and Littlewood wrote later in his book, A Mathematician's Miscellany that his rediscovery of the result did not shed a positive light on the isolated nature of British mathematics at the time.

Subsets and Splits

No community queries yet

The top public SQL queries from the community will appear here once available.