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Affine coordinates Examples Affine_space > Examples The solutions of an inhomogeneous linear differential equation form an affine space over the solutions of the corresponding homogeneous linear equation. Generalizing all of the above, if T: V → W is a linear map and y lies in its image, the set of solutions x ∈ V to the equation Tx = y is a coset of the kernel of T , and is therefore an affine space over Ker T . The space of (linear) complementary subspaces of a vector subspace V in a vector space W is an affine space, over Hom(W/V, V). |
Tactile hallucinations In Parkinson's disease Tactile_hallucination > In Parkinson's disease Several other patients felt that there was a parasitic infestation of their skin which caused lesions on their skins due to the obsessive need of itching. Fénelon also analyzed the particular types of tactile hallucinations experienced, the timing of such experience and certain drugs that could eliminate such experience. It was concluded that patients with both PD and tactile hallucinations not only experienced sensations elicited by insects under their skin but also by vivid tactile sensations of people. |
Thermodynamic integration Summary Thermodynamic_integration Thermodynamic integration is a method used to compare the difference in free energy between two given states (e.g., A and B) whose potential energies U A {\displaystyle U_{A}} and U B {\displaystyle U_{B}} have different dependences on the spatial coordinates. Because the free energy of a system is not simply a function of the phase space coordinates of the system, but is instead a function of the Boltzmann-weighted integral over phase space (i.e. partition function), the free energy difference between two states cannot be calculated directly from the potential energy of just two coordinate sets (for state A and B respectively). In thermodynamic integration, the free energy difference is calculated by defining a thermodynamic path between the states and integrating over ensemble-averaged enthalpy changes along the path. Such paths can either be real chemical processes or alchemical processes. An example alchemical process is the Kirkwood's coupling parameter method. |
Working fluids Properties and states Working_fluid > Properties and states This is usually done on a property diagram which is simply a plot of one property versus another. When the working fluid passes through engineering components such as turbines and compressors, the point on a property diagram moves due to the possible changes of certain properties. In theory therefore it is possible to draw a line/curve which fully describes the thermodynamic properties of the fluid. |
Dynamic network analysis Overview Dynamic_network_analysis > Overview There are two aspects of this field. The first is the statistical analysis of DNA data. The second is the utilization of simulation to address issues of network dynamics. DNA networks vary from traditional social networks in that they are larger, dynamic, multi-mode, multi-plex networks, and may contain varying levels of uncertainty. |
Computability in Analysis and Physics Topics Computability_in_Analysis_and_Physics > Topics The book concerns computable analysis, a branch of mathematical analysis founded by Alan Turing and concerned with the computability of constructions in analysis. This area is connected to, but distinct from, constructive analysis, reverse mathematics, and numerical analysis. The early development of the field was summarized in a book by Oliver Aberth, Computable Analysis (1980), and Computability in Analysis and Physics provides an update, incorporating substantial developments in this area by its authors. |
Social communication Summary Social_communication For example, many flowers use symmetrical shapes and colors that stand out from their surroundings in order to signal to insects where nectar is located to attract them. Humans also practice interspecies communication, for example, when interacting with pets. The field of communication includes various other issues, like communicative competence and the history of communication. |
Linear combinations of atomic orbitals Mathematical description Linear_combination_of_atomic_orbitals_molecular_orbital_method > Mathematical description This reducible representation is decomposed into the sum of irreducible representations. These irreducible representations correspond to the symmetry of the orbitals involved. Molecular orbital diagrams provide simple qualitative LCAO treatment. The Hückel method, the extended Hückel method and the Pariser–Parr–Pople method, provide some quantitative theories. |
Radionics History Radionics > History According to the theory, all human bodies give off unique or characteristic "radiations" as do all other physical bodies or objects. Such radiations are often termed an "aura". Radiesthesia is cited as the explanation of such phenomena as dowsing by rods and pendulums in order to locate buried substances, diagnose illnesses, and the like. |
List of binary codes Summary List_of_binary_codes This is a list of some binary codes that are (or have been) used to represent text as a sequence of binary digits "0" and "1". Fixed-width binary codes use a set number of bits to represent each character in the text, while in variable-width binary codes, the number of bits may vary from character to character. the binary codes are used to read the computer language. |
Gravity anomaly Definition Gravity_anomaly > Definition Richter was equipped with a highly precise pendulum clock which had been carefully calibrated at Paris before his departure. However, he found that the clock ran too slowly in Cayenne, compared with the apparent motion of the stars. Fifteen years later, Isaac Newton used his newly formulated universal theory of gravitation to explain the anomaly. |
Object-oriented analysis and design History Object-oriented_analysis_and_design > History In 1994, the Three Amigos of Rational Software started working together to develop the Unified Modeling Language (UML). Later, together with Philippe Kruchten and Walker Royce (eldest son of Winston Royce), they have led a successful mission to merge their own methodologies, OMT, OOSE and Booch method, with various insights and experiences from other industry leaders into the Rational Unified Process (RUP), a comprehensive iterative and incremental process guide and framework for learning industry best practices of software development and project management. Since then, the Unified Process family has become probably the most popular methodology and reference model for object-oriented analysis and design. |
Small-conductance mechanosensitive channel Function Small-conductance_mechanosensitive_channel > Function MS channels function as electromechanical switches with the capability to sense the physical state of lipid bilayers. Interactions with the membrane lipids are responsible for the sensing of mechanical force for most known MS channels. In bacterial and animal systems, MS ion channels are thought to mediate the perception of pressure, touch, and sound. |
Repeated measures design Design and analysis of experiments Repeated_measures_ANOVA > References > Design and analysis of experiments Jones, Byron; Kenward, Michael G. (2003). Design and Analysis of Cross-Over Trials (Second ed.). London: Chapman and Hall. |
T regulatory cell Development Regulatory_T_cell > Development Its development is mainly dependent on IL-15. This subset has lower affinity for self antigens than CD25+Foxp3high subset. |
Terraforming of Venus Space-based Terraforming_of_Venus > Proposed approaches to terraforming > Cooling planet by solar shades > Space-based Solar shades could also serve as solar power generators. Space-based solar shade techniques, and thin-film solar sails in general, are only in an early stage of development. The vast sizes require a quantity of material that is many orders of magnitude greater than any human-made object that has ever been brought into space or constructed in space. |
Frontier Orbital Theory Sigmatropic reactions Frontier_molecular_orbital_theory > Applications > Sigmatropic reactions Assuming the reaction happens suprafacially, the shift results with the HOMO of butadiene on the 4 carbons that are not involved in the sigma bond of the product. Since the pi system changed from the LUMO to the HOMO, this reaction is allowed (though it would not be allowed if the pi system went from LUMO to LUMO). To explain why the reaction happens suprafacially, first notice that the terminal orbitals are in the same phase. |
Convergence in measure Definitions Convergence_in_measure > Definitions Let f , f n ( n ∈ N ): X → R {\displaystyle f,f_{n}\ (n\in \mathbb {N} ):X\to \mathbb {R} } be measurable functions on a measure space ( X , Σ , μ ) {\displaystyle (X,\Sigma ,\mu )} . The sequence f n {\displaystyle f_{n}} is said to converge globally in measure to f {\displaystyle f} if for every ε > 0 {\displaystyle \varepsilon >0} , lim n → ∞ μ ( { x ∈ X: | f ( x ) − f n ( x ) | ≥ ε } ) = 0 {\displaystyle \lim _{n\to \infty }\mu (\{x\in X:|f(x)-f_{n}(x)|\geq \varepsilon \})=0} ,and to converge locally in measure to f {\displaystyle f} if for every ε > 0 {\displaystyle \varepsilon >0} and every F ∈ Σ {\displaystyle F\in \Sigma } with μ ( F ) < ∞ {\displaystyle \mu (F)<\infty } , lim n → ∞ μ ( { x ∈ F: | f ( x ) − f n ( x ) | ≥ ε } ) = 0 {\displaystyle \lim _{n\to \infty }\mu (\{x\in F:|f(x)-f_{n}(x)|\geq \varepsilon \})=0} .On a finite measure space, both notions are equivalent. Otherwise, convergence in measure can refer to either global convergence in measure or local convergence in measure, depending on the author. |
Cardiac amyloidosis Treatments Cardiac_amyloidosis > Treatments For familial amyloidosis, ACE-inhibitors and beta-blockers can be prescribed if there is no autonomic neuropathy. Suppression of transthyretin production: liver transplantation and medications that decreases the activity of the transthyretin genes (patisiran and inotersen). In patients with familial transthyretin mutations, liver transplantation can provide the body with a source of normal transthyretin. |
Image histogram Summary Image_histogram An image histogram is a type of histogram that acts as a graphical representation of the tonal distribution in a digital image. It plots the number of pixels for each tonal value. By looking at the histogram for a specific image a viewer will be able to judge the entire tonal distribution at a glance. |
Mordehai Milgrom Milgrom and modified Newtonian dynamics Mordehai_Milgrom > Milgrom and modified Newtonian dynamics Milgrom suggests that Newton's law of universal gravitation should be modified for very small accelerations, typically of the order of 10−11g and less. |
Floral symmetry Symmetry groups Floral_symmetry > Symmetry groups Monocots that exhibit rotational symmetry but not mirror symmetry (for instance, if their petals exhibit chirality) are described by the cyclic group of order 3, C 3 {\displaystyle C_{3}} , and monocots with both rotational symmetry and reflection symmetry about 3 axes are described by the dihedral group of dimension 3, D 3 {\displaystyle D_{3}} . Eudicots with tetramerous or pentamerous petals are often invariant under rotations by π / 2 {\displaystyle \pi /2} or 2 π / 5 {\displaystyle 2\pi /5} . Again, whether they also have mirror planes decides whether they belong to dihedral ( D 4 {\displaystyle D_{4}} and D 5 {\displaystyle D_{5}} ) or cyclic groups ( C 4 {\displaystyle C_{4}} or C 5 {\displaystyle C_{5}} ). |
Mitotic catastrophe DNA damage Mitotic_catastrophe > Causes > DNA damage The response to DNA damage present during mitosis is different from the response to DNA damage detected during the rest of the cell cycle. Cells can detect DNA defects during the rest of the cell cycle and either repair them if possible or undergo apoptosis of senescence. Given that when this happens the cell does not progress into mitosis it is not considered a mitotic catastrophe. |
Mathematical fallacies Summary False_proof The latter usually applies to a form of argument that does not comply with the valid inference rules of logic, whereas the problematic mathematical step is typically a correct rule applied with a tacit wrong assumption. Beyond pedagogy, the resolution of a fallacy can lead to deeper insights into a subject (e.g., the introduction of Pasch's axiom of Euclidean geometry, the five colour theorem of graph theory). |
Brain–brain interface Summary Brain-brain_interface Such a computing structure could define the first example of an organic computer capable of solving heuristic problems that would be deemed non-computable by a general Turing-machine. Future works will elucidate in detail the characteristics of this multi-brain system, its computational capabilities, and how it compares to other non-Turing computational architectures Miguel Nicolelis of Duke University, one of the investigators who did the experiment with rats, has done previous work using a brain–computer interface. == References == |
Controller Area Network Automotive Controller_Area_Network > Applications > Automotive Examples include: Auto start/stop: Various sensor inputs from around the vehicle (speed sensors, steering angle, air conditioning on/off, engine temperature) are collated via the CAN bus to determine whether the engine can be shut down when stationary for improved fuel economy and emissions. Electric park brakes: The hill hold functionality takes input from the vehicle's tilt sensor (also used by the burglar alarm) and the road speed sensors (also used by the ABS, engine control and traction control) via the CAN bus to determine if the vehicle is stopped on an incline. Similarly, inputs from seat belt sensors (part of the airbag controls) are fed from the CAN bus to determine if the seat belts are fastened, so that the parking brake will automatically release upon moving off. |
Vladimir Krivchenkov Interpretation of Quantum mechanics Vladimir_Krivchenkov > Interpretation of Quantum mechanics According to Krivchenkov, the intents to "interpret" quantum mechanics in terms of classical mechanics have no more sense than interpretation of heliocentric cosmological system in terms of geocentric system. Only the old tradition forced the physicists to discuss the so-called Copenhagen interpretation of quantum mechanics. Quantum mechanics is completely deterministic systems, where any event always has a cause and any cause always has an effect. However, some quantum mechanical systems are complicated, so we have to describe them classically (quasi-classically, semi-classically, pseudo-classically, ...). |
Homogeneous system of linear equations Trivial example Simultaneous_linear_equations > Elementary examples > Trivial example The system of one equation in one unknown 2 x = 4 {\displaystyle 2x=4} has the solution x = 2. {\displaystyle x=2.} However, a linear system is commonly considered as having at least two equations. |
Burnishing (metal) Effects on sliding contact Burnishing_(metal) > Effects on sliding contact This reduces the precision and accuracy of the machine. The combination of higher friction and degraded form often leads to a runaway situation that continually worsens until the component fails. To prevent destructive burnishing, sliding must be avoided, and in rolling situations, loads must be beneath the spalling threshold. |
Diamond buffer High output current derivatives Diamond_buffer > High output current derivatives If efficiency and cost are critical, the circuit can be further improved for higher current handling at low idle currents. In the simplest form, the circuit is augmented with a reverse diode connected to the bases of the output transistors. At high output currents the diode opens, and the diamond operates as a conventional two-stage emitter follower. |
Ernst Mayr Ideas Ernst_Mayr > Ideas Current molecular studies in evolution and speciation indicate that although allopatric speciation is the norm, there are numerous cases of sympatric speciation in groups with greater mobility, such as birds. The precise mechanisms of sympatric speciation, however, are usually a form of microallopatry enabled by variations in niche occupancy among individuals within a population. In many of his writings, Mayr rejected reductionism in evolutionary biology, arguing that evolutionary pressures act on the whole organism, not on single genes, and that genes can have different effects depending on the other genes present. |
Argininosuccinic acid Reactions Argininosuccinic_acid > Reactions Some cells synthesize argininosuccinic acid from citrulline and aspartic acid and use it as a precursor for arginine in the urea cycle or citrulline-NO cycle. The enzyme that catalyzes the reaction is argininosuccinate synthetase.Argininosuccinic acid is a precursor to fumarate in the citric acid cycle via argininosuccinate lyase. |
Vopěnka's principle Summary Vopěnka's_principle According to Pudlák (2013, p. 204), Vopěnka's principle was originally intended as a joke: Vopěnka was apparently unenthusiastic about large cardinals and introduced his principle as a bogus large cardinal property, planning to show later that it was not consistent. However, before publishing his inconsistency proof he found a flaw in it. |
Photoheterotroph Ecology Photoheterotroph > Ecology Notably, temperature and pH drive anoxygenic phototroph community composition in Yellowstone National Park's geothermal features. In addition, various, light-dependent niches in the Great Salk Lake's hypersaline mats support phototrophic diversity as microbes optimize energy production and combat osmotic stress.Biogeochemical Cycling Photoheterotrophs influence global carbon cycling by assimilating dissolved organic carbon (DOC). Therefore, when harvesting light-energy, carbon is maintained in the microbial loop without corresponding respiration (i.e., carbon dioxide release to the atmosphere as DOC is oxidized to fuel energy production). This disconnect, the discovery of facultative photoheterotrophs (e.g., AAPs with flexible energy sources), and previous measurements taken in the dark (i.e., to avoid skewed oxygen consumption values due to photooxidation, UV light, and oxygenic photosynthesis) lead to overestimated aquatic CO2 emissions. For example, a 15.2% decrease in community respiration was observed in Cep Lake, Czechia—alongside preferential glucose and pyruvate uptake—is attributed to facultative photoheterotrophs preferring light-energy during the daytime, given fitness benefits mentioned previously. |
Zermelo–Fraenkel set theory Summary Zermelo-Fraenkel_axioms For example, the axiom of pairing says that given any two sets a {\displaystyle a} and b {\displaystyle b} there is a new set { a , b } {\displaystyle \{a,b\}} containing exactly a {\displaystyle a} and b {\displaystyle b} . Other axioms describe properties of set membership. |
Cloacal membrane Summary Cloacal_membrane Before the urorectal septum has an opportunity to fuse with the cloacal membrane, the membrane ruptures, exposing the urogenital sinus and dorsal anorectal canal to the exterior. Later on, an ectodermal plug, the anal membrane, forms to create the lower third of the rectum. It ruptures in the seventh week of gestation. |
Histogram matching Implementation Histogram_specification > Implementation Consider a grayscale input image X. It has a probability density function pr(r), where r is a grayscale value, and pr(r) is the probability of that value. This probability can easily be computed from the histogram of the image by p r ( r j ) = n j n {\textstyle p_{r}(r_{j})={n_{j} \over n}} Where nj is the frequency of the grayscale value rj, and n is the total number of pixels in the image. Now consider a desired output probability density function pz(z). A transformation of pr(r) is needed to convert it to pz(z). |
Quantum cellular automata Summary Quantum_cellular_automata A quantum cellular automaton (QCA) is an abstract model of quantum computation, devised in analogy to conventional models of cellular automata introduced by John von Neumann. The same name may also refer to quantum dot cellular automata, which are a proposed physical implementation of "classical" cellular automata by exploiting quantum mechanical phenomena. QCA have attracted a lot of attention as a result of its extremely small feature size (at the molecular or even atomic scale) and its ultra-low power consumption, making it one candidate for replacing CMOS technology. |
Edgeworth's limit theorem Illustration when there are only two commodities Edgeworth's_limit_theorem > Illustration when there are only two commodities Francis Ysidro Edgeworth first described what later became known as the limit theorem in his book Mathematical Psychics (1881). He used a variant of what is now known as the Edgeworth box (with quantities traded, rather than quantities possessed, on the relevant axes) to analyse trade between groups of traders of various sizes. In general he found that 'Contract without competition is indeterminate, contract with perfect competition is perfectly determinate, contract with more or less perfect competition is less or more indeterminate.' |
Insertion Sort Variants Binary_insertion_sort > Variants A variant named binary merge sort uses a binary insertion sort to sort groups of 32 elements, followed by a final sort using merge sort. It combines the speed of insertion sort on small data sets with the speed of merge sort on large data sets.To avoid having to make a series of swaps for each insertion, the input could be stored in a linked list, which allows elements to be spliced into or out of the list in constant time when the position in the list is known. However, searching a linked list requires sequentially following the links to the desired position: a linked list does not have random access, so it cannot use a faster method such as binary search. |
Bootstrap compiler Advantages Bootstrapping_(compilers) > Advantages Bootstrapping a compiler has the following advantages: It is a non-trivial test of the language being compiled, and as such is a form of dogfooding. Compiler developers and bug reporters only need to know the language being compiled. Compiler development can be performed in the higher-level language being compiled. Improvements to the compiler's back-end improve not only general-purpose programs but also the compiler itself. It is a comprehensive consistency check as it should be able to reproduce its own object code.Note that some of these points assume that the language runtime is also written in the same language. |
Solvent suppression Introduction Solvent_suppression > Introduction In liquid-state NMR spectroscopy, the sample to be studied is dissolved in a solvent. Typically, the concentration of the solvent is much higher than the concentration of the solutes of interest. The signal from the solvent can overwhelm that of the solute, and the NMR instrument may not collect any meaningful data. Solvent suppression techniques are particularly important in protein NMR where the solvent often includes H2O as well as D2O. == References == |
String theorist Extra dimensions Ten-dimensional_space > Fundamentals > Extra dimensions A Calabi–Yau manifold is a special space which is typically taken to be six-dimensional in applications to string theory. It is named after mathematicians Eugenio Calabi and Shing-Tung Yau.Another approach to reducing the number of dimensions is the so-called brane-world scenario. In this approach, physicists assume that the observable universe is a four-dimensional subspace of a higher dimensional space. In such models, the force-carrying bosons of particle physics arise from open strings with endpoints attached to the four-dimensional subspace, while gravity arises from closed strings propagating through the larger ambient space. This idea plays an important role in attempts to develop models of real-world physics based on string theory, and it provides a natural explanation for the weakness of gravity compared to the other fundamental forces. |
Direct Rendering Manager Kernel Mode Setting Graphics_Execution_Manager > Software architecture > Kernel Mode Setting It not only breaks the isolation that operating systems should provide between programs and hardware, raising both stability and security concerns, but also could leave the graphics hardware in an inconsistent state if two or more user space programs try to do the mode-setting at the same time. To avoid these conflicts, the X Server became in practice the only user space program that performed mode-setting operations; the remainder user space programs relied on the X Server to set the appropriate mode and to handle any other operation involving mode-setting. Initially the mode-setting was performed exclusively during the X Server startup process, but later the X Server gained the ability to do it while running. |
Capsule neural network Routing by agreement Capsule_neural_network > Routing by agreement At each iteration, the coefficients are adjusted via a "routing" softmax so that they continue to sum to 1 (to express the probability that a given capsule is the parent of a given child.) Softmax amplifies larger values and diminishes smaller values beyond their proportion of the total. |
Transmission towers Stockbridge dampers Power_transmission_tower > Other features > Stockbridge dampers Stockbridge dampers are added to the transmission lines a meter or two from the tower. They consist of a short length of cable clamped in place parallel to the line itself and weighted at each end. The size and dimensions are carefully designed to damp any buildup of mechanical oscillation of the lines that could be induced by mechanical vibration most likely that caused by wind. Without them it's possible for a standing wave to become established that grows in magnitude and destroys the line or the tower. |
Sigma hole interactions Strength Sigma_hole_interactions > Characteristics > Strength At any angle, it can be observed that the interaction is stronger when the Bromine atom hosting the sigma hole is bound to a strongly electron withdrawing cyano group than when this atom is bound to a trifluoromethyl group, which is only moderately electron withdrawing. On the other hand, the interaction is stronger when an ammonia molecule provides the lone pair, as the electrostatic potential associated with this site is more negative than the corresponding site on hydrogen cyanide. In all cases, the interaction is becomes stronger at more linear angles. |
Object composition Summary Object_composition In computer science, object composition and object aggregation are closely related ways to combine objects or data types into more complex ones. In conversation the distinction between composition and aggregation is often ignored. Common kinds of compositions are objects used in object-oriented programming, tagged unions, sets, sequences, and various graph structures. |
Irreversible Process History Irreversible_change > History From 1872 to 1875, Ludwig Boltzmann reinforced the statistical explanation of this paradox in the form of Boltzmann's entropy formula, stating that an increase of the number of possible microstates a system might be in, will increase the entropy of the system, making it less likely that the system will return to an earlier state. His formulas quantified the analysis done by William Thomson, 1st Baron Kelvin, who had argued that: The equations of motion in abstract dynamics are perfectly reversible; any solution of these equations remains valid when the time variable t is replaced by –t. On the other hand, physical processes are irreversible: for example, the friction of solids, conduction of heat, and diffusion. |
Foreland basin Plate motion and seismicity Foreland_basin > Plate motion and seismicity Thus, it is crucial to consider non-GPS models to determine the long-term evolution of continental collisions and in how it helped develop the adjacent foreland basins. Comparing both modern GPS (Sella et al. 2002) and non-GPS models allows deformation rates to be calculated. Comparing these numbers to the geologic regime helps constrain the number of probable models as well as which model is more geologically accurate within a specific region. Seismicity determines where active zones of seismic activity occur as well as measure the total fault displacements and the timing of the onset of deformation. |
Vector DNA Summary Vector_DNA In molecular cloning, a vector is any particle (e.g., plasmids, cosmids, Lambda phages) used as a vehicle to artificially carry a foreign nucleic sequence – usually DNA – into another cell, where it can be replicated and/or expressed. A vector containing foreign DNA is termed recombinant DNA. The four major types of vectors are plasmids, viral vectors, cosmids, and artificial chromosomes. Of these, the most commonly used vectors are plasmids. |
Catastrophic interference Generative replay Catastrophic_interference > Proposed solutions > Rehearsal > Generative replay In recent years, pseudo-rehearsal has re-gained in popularity thanks to the progress in the capabilities of deep generative models. When such deep generative models are used to generate the "pseudo-data" to be rehearsed, this method is typically referred to as generative replay. Such generative replay can effectively prevent catastrophic forgetting, especially when the replay is performed in the hidden layers rather than at the input level. |
Cross pollination Process of pollination Cross_pollination > Process of pollination Spore mother cells in the microsporangia divide by meiosis to form haploid microspores that develop further by two mitotic divisions into immature male gametophytes (pollen grains). The four resulting cells consist of a large tube cell that forms the pollen tube, a generative cell that will produce two sperm by mitosis, and two prothallial cells that degenerate. These cells comprise a very reduced microgametophyte, that is contained within the resistant. |
Maximin strategy The Stag Hunt Maximin_strategy > Socially Desirable Outcomes > Pareto Optimality > The Stag Hunt It is imperative to note that Pareto optimality is not a strategic solution for simultaneous games. However, the ideal informs players about the potential for more efficient outcomes. Moreover, potentially providing insight into how players should learn to play over time. |
Flow density Transport fluxes Photon_flux > Flux as flow rate per unit area > Transport fluxes Eight of the most common forms of flux from the transport phenomena literature are defined as follows: Momentum flux, the rate of transfer of momentum across a unit area (N·s·m−2·s−1). (Newton's law of viscosity) Heat flux, the rate of heat flow across a unit area (J·m−2·s−1). (Fourier's law of conduction) (This definition of heat flux fits Maxwell's original definition.) Diffusion flux, the rate of movement of molecules across a unit area (mol·m−2·s−1). |
Population standard deviation History 5_sigma > History The term standard deviation was first used in writing by Karl Pearson in 1894, following his use of it in lectures. This was as a replacement for earlier alternative names for the same idea: for example, Gauss used mean error. |
Advection–diffusion equation Understanding the terms involved Convection–diffusion_transport_equation > Equation > Understanding the terms involved Thus, the concentration at a given location can change because of the flow. The final contribution, R, describes the creation or destruction of the quantity. For example, if c is the concentration of a molecule, then R describes how the molecule can be created or destroyed by chemical reactions. |
Hydroxyl radical In Earth's atmosphere Hydroxyl_radicals > In Earth's atmosphere The results obtained by Montzka et al. (2011) shows that the interannual variability in •OH estimated from CH3CCl3 measurements is small, indicating that global •OH is generally well buffered against perturbations. This small variability is consistent with measurements of methane and other trace gases primarily oxidized by •OH, as well as global photochemical model calculations. In 2014, researchers reported their discovery of a "hole" or absence of hydroxyl throughout the entire depth of the troposphere across a large region of the tropical West Pacific. They suggested that this hole is permitting large quantities of ozone-degrading chemicals to reach the stratosphere, and that this may be significantly reinforcing ozone depletion in the polar regions with potential consequences for the climate of the Earth. |
HP 35s Complex numbers HP_35s > Feature details > Complex numbers Previous (and other current) HP calculators have handled complex numbers in a variety of ways. In the HP 33s, complex numbers were stored as two separate values, and the "complex" modifier was used to indicate that an operation was to treat the stack as containing complex numbers. For example, adding 12 + 34i and 56 + 78i involved the following keystrokes: 34↵ Enter12↵ Enter78↵ Enter56CMPLX+, which used up all four stack levels.The 35s stores complex numbers as single values, which can then be operated on in the standard ways. The above example of adding 12 + 34i and 56 + 78i then becomes: 12i34↵ Enter56i78+. |
Atomic bombing Other types Nuclear_warheads > Types > Other types There are other types of nuclear weapons as well. For example, a boosted fission weapon is a fission bomb that increases its explosive yield through a small number of fusion reactions, but it is not a fusion bomb. In the boosted bomb, the neutrons produced by the fusion reactions serve primarily to increase the efficiency of the fission bomb. There are two types of boosted fission bomb: internally boosted, in which a deuterium-tritium mixture is injected into the bomb core, and externally boosted, in which concentric shells of lithium-deuteride and depleted uranium are layered on the outside of the fission bomb core. |
Evolution theory Epigenetics Biological_evolution > Sources of variation > Epigenetics Developmental biologists suggest that complex interactions in genetic networks and communication among cells can lead to heritable variations that may underlay some of the mechanics in developmental plasticity and canalisation. Heritability may also occur at even larger scales. For example, ecological inheritance through the process of niche construction is defined by the regular and repeated activities of organisms in their environment. This generates a legacy of effects that modify and feed back into the selection regime of subsequent generations. Other examples of heritability in evolution that are not under the direct control of genes include the inheritance of cultural traits and symbiogenesis. |
Alkali metals Reactivity Alkali_metal_compound > Periodic trends > Reactivity The atomisation energy measures the strength of the metallic bond of an element, which falls down the group as the atoms increase in radius and thus the metallic bond must increase in length, making the delocalised electrons further away from the attraction of the nuclei of the heavier alkali metals. Adding the atomisation and first ionisation energies gives a quantity closely related to (but not equal to) the activation energy of the reaction of an alkali metal with another substance. This quantity decreases going down the group, and so does the activation energy; thus, chemical reactions can occur faster and the reactivity increases down the group. |
Hydration shell Hydration shells of proteins Solvation_shell > Hydration shells of proteins The hydration shell (also sometimes called hydration layer) that forms around proteins is of particular importance in biochemistry. This interaction of the protein surface with the surrounding water is often referred to as protein hydration and is fundamental to the activity of the protein. The hydration layer around a protein has been found to have dynamics distinct from the bulk water to a distance of 1 nm. The duration of contact of a specific water molecule with the protein surface may be in the subnanosecond range while molecular dynamics simulations suggest the time water spends in the hydration shell before mixing with the outside bulk water could be in the femtosecond to picosecond range, and that near features conventionally regarded as attractive to water, such as hydrogen bond donors, the water molecules are actually relatively weakly bound and are easily displaced. Solvation shell water molecules can also influence the molecular design of protein binders or inhibitors.With other solvents and solutes, varying steric and kinetic factors can also affect the solvation shell. |
Organic life Living systems theories Organic_life > Definitions > Living systems theories Living systems are open self-organizing living things that interact with their environment. These systems are maintained by flows of information, energy, and matter. Budisa, Kubyshkin and Schmidt defined cellular life as an organizational unit resting on four pillars/cornerstones: (i) energy, (ii) metabolism, (iii) information and (iv) form. This system is able to regulate and control metabolism and energy supply and contains at least one subsystem that functions as an information carrier (genetic information). |
Primary progressive multiple sclerosis Management Multiple_Sclerosis > Management Although no cure for multiple sclerosis has been found, several therapies have proven helpful. Several effective treatments can decrease the number of attacks and the rate of progression. The primary aims of therapy are returning function after an attack, preventing new attacks, and preventing disability. Starting medications is generally recommended in people after the first attack when more than two lesions are seen on MRI.The first approved medications used to treat MS were modestly effective, though were poorly tolerated and had many adverse effects. |
Aberration of starlight Explanation Constant_of_aberration > Explanation Since the direction of motion of the Earth changes during its orbit, the direction of this tilting changes during the course of the year, and causes the apparent position of the star to differ from its true position as measured in the inertial frame of the Sun. While classical reasoning gives intuition for aberration, it leads to a number of physical paradoxes observable even at the classical level (see history). The theory of special relativity is required to correctly account for aberration. The relativistic explanation is very similar to the classical one however, and in both theories aberration may be understood as a case of addition of velocities. |
Collapsed lung Tension pneumothorax Tension_pneumothorax > Signs and symptoms > Tension pneumothorax Other findings may include quieter breath sounds on one side of the chest, low oxygen levels and blood pressure, and displacement of the trachea away from the affected side. Rarely, there may be cyanosis (bluish discoloration of the skin due to low oxygen levels), altered level of consciousness, a hyperresonant percussion note on examination of the affected side with reduced expansion and decreased movement, pain in the epigastrium (upper abdomen), displacement of the apex beat (heart impulse), and resonant sound when tapping the sternum.Tension pneumothorax may also occur in someone who is receiving mechanical ventilation, in which case it may be difficult to spot as the person is typically receiving sedation; it is often noted because of a sudden deterioration in condition. Recent studies have shown that the development of tension features may not always be as rapid as previously thought. Deviation of the trachea to one side and the presence of raised jugular venous pressure (distended neck veins) are not reliable as clinical signs. |
Data segment Summary Data_segment In computing, a data segment (often denoted .data) is a portion of an object file or the corresponding address space of a program that contains initialized static variables, that is, global variables and static local variables. The size of this segment is determined by the size of the values in the program's source code, and does not change at run time. The data segment is read/write, since the values of variables can be altered at run time. This is in contrast to the read-only data segment (rodata segment or .rodata), which contains static constants rather than variables; it also contrasts to the code segment, also known as the text segment, which is read-only on many architectures. |
Geometric object History Geometric_object > History Eudoxus (408–c. 355 BC) developed the method of exhaustion, which allowed the calculation of areas and volumes of curvilinear figures, as well as a theory of ratios that avoided the problem of incommensurable magnitudes, which enabled subsequent geometers to make significant advances. Around 300 BC, geometry was revolutionized by Euclid, whose Elements, widely considered the most successful and influential textbook of all time, introduced mathematical rigor through the axiomatic method and is the earliest example of the format still used in mathematics today, that of definition, axiom, theorem, and proof. |
Economic risk Risk and uncertainty Risk_takers > Other considerations > Risk and uncertainty Measurement of risk: A set of possibilities each with quantified probabilities and quantified losses. Example: "There is a 40% chance the proposed oil well will be dry with a loss of $12 million in exploratory drilling costs. "In this sense, one may have uncertainty without risk but not risk without uncertainty. |
Glossary of systems theory D Glossary_of_systems_theory > D Development: The process of liberating a system from its previous set of limiting conditions. It is an amelioration of conditions or quality. Dissipative structure: A term invented by Ilya Prigogine to describe complex chemical structures undergoing the process of chemical change through the dissipation of entropy into their environment, and the corresponding importation of "negentropy" from their environment. Also known as syntropic systems. |
Train inspection system Technologies Train_inspection_system > Technologies Many are stand-alone detectors, but most often are integrated into bearing temperature scanning locations. High/wide sensors These are able to measure the height and width of rolling stock, so that cars and loads which won't fit under bridges or through tunnels are stopped. Most often they are optical line of sight devices that trigger an alarm when the beam is broken. |
Linux console Summary Linux_console The Linux console is a system console internal to the Linux kernel. A system console is the device which receives all kernel messages and warnings and which allows logins in single user mode. The Linux console provides a way for the kernel and other processes to send text output to the user, and to receive text input from the user. The user typically enters text with a computer keyboard and reads the output text on a computer monitor. |
Cluster headache Summary Cluster_headache Men are affected about four times more often than women. Cluster headaches are named for the occurrence of groups of headache attacks (clusters). They have also been referred to as "suicide headaches". |
Conjecture P versus NP problem Conjecture > Important examples > P versus NP problem The P versus NP problem is a major unsolved problem in computer science. Informally, it asks whether every problem whose solution can be quickly verified by a computer can also be quickly solved by a computer; it is widely conjectured that the answer is no. It was essentially first mentioned in a 1956 letter written by Kurt Gödel to John von Neumann. Gödel asked whether a certain NP-complete problem could be solved in quadratic or linear time. The precise statement of the P=NP problem was introduced in 1971 by Stephen Cook in his seminal paper "The complexity of theorem proving procedures" and is considered by many to be the most important open problem in the field. It is one of the seven Millennium Prize Problems selected by the Clay Mathematics Institute to carry a US$1,000,000 prize for the first correct solution. |
Energy infrastructure Fossil fuels Energy_production > Fossil fuels Fossil fuels are currently economical for decentralized energy use. Energy dependence on imported fossil fuels creates energy security risks for dependent countries. Oil dependence in particular has led to war, funding of radicals, monopolization, and socio-political instability.Fossil fuels are non-renewable resources, which will eventually decline in production and become exhausted. |
Nanocircuitry Production methods Nanocircuitry > Production methods The first part of their organization begins with transistors. As of right now, most electronics are using silicon-based transistors. Transistors are an integral part of circuits as they control the flow of electricity and transform weak electrical signals to strong ones. |
Immortal DNA strand hypothesis Evidence Immortal_DNA_strand_hypothesis > Evidence Some features may not be present in vivo or may be absent in vitro. In May 2007 evidence in support of the Immortal DNA Strand theory was discovered by Michael Conboy et al., using the muscle stem/satellite cell model during tissue regeneration, where there is tremendous cell division during a relatively brief period of time. Using two BrdU analogs to label template and newly synthesized DNA strands, they saw that about half of the dividing cells in regenerating muscle sort the older "Immortal" DNA to one daughter cell and the younger DNA to the other. |
Introduction to gauge theory Gauge bosons Introduction_to_gauge_theory > In quantum mechanics > Gauge bosons We then measure the two waves at some other, nearby point, in order to determine their wavelengths. But there are two entirely different reasons that the waves could have changed. They could have changed because they were oscillating with a certain wavelength, or they could have changed because the gauge function changed from a 20–80 mixture to, say, 21–79. |
JavaScript syntax Methods ECMAScript_syntax > Objects > Methods (There are also call and apply methods that can set this explicitly—some packages such as jQuery do unusual things with this.) In the example below, Foo is being used as a constructor. There is nothing special about a constructor - it is just a plain function that initialises an object. |
Sequence determination Significance Sequence_determination > Significance The underlying concept is that each of the sequences will produce a distinctive result that can be visualized or measured. In some instances, the results will be essentially conclusive with only one reasonable interpretation. In other situations, the results may be less definite in that the observed features may permit more than one interpretation of the original sequence. == References == |
In-place matrix transposition Summary In-place_matrix_transposition In contrast, for a square matrix (N = M), all of the cycles are of length 1 or 2, and the transpose can be achieved by a simple loop to swap the upper triangle of the matrix with the lower triangle. Further complications arise if one wishes to maximize memory locality in order to improve cache line utilization or to operate out-of-core (where the matrix does not fit into main memory), since transposes inherently involve non-consecutive memory accesses. The problem of non-square in-place transposition has been studied since at least the late 1950s, and several algorithms are known, including several which attempt to optimize locality for cache, out-of-core, or similar memory-related contexts. |
Three-stage quantum cryptography protocol Summary Three-stage_quantum_cryptography_protocol The three-stage quantum cryptography protocol, also known as Kak's three-stage protocol is a method of data encryption that uses random polarization rotations by both Alice and Bob, the two authenticated parties, that was proposed by Subhash Kak. In principle, this method can be used for continuous, unbreakable encryption of data if single photons are used. It is different from methods of QKD (quantum key distribution) for it can be used for direct encryption of data, although it could also be used for exchanging keys. The basic idea behind this method is that of sending secrets (or valuables) through an unreliable courier by having both Alice and Bob place their locks on the box containing the secret, which is also called double-lock cryptography. |
Devicetree Summary Device_tree In computing, a devicetree (also written device tree) is a data structure describing the hardware components of a particular computer so that the operating system's kernel can use and manage those components, including the CPU or CPUs, the memory, the buses and the integrated peripherals. The device tree was derived from SPARC-based computers via the Open Firmware project. The current Devicetree specification is targeted at smaller systems, but is still used with some server-class systems (for instance, those described by the Power Architecture Platform Reference). |
Pulse dialling Summary Pulse_dialing Pulse dialing is a signaling technology in telecommunications in which a direct current local loop circuit is interrupted according to a defined coding system for each signal transmitted, usually a digit. This lends the method the often used name loop disconnect dialing. In the most common variant of pulse dialing, decadic dialing, each of the ten Arabic numerals are encoded in a sequence of up to ten pulses. |
Octet (computing) Definition Octet_(computing) > Definition The international standard IEC 60027-2, chapter 3.8.2, states that a byte is an octet of bits. However, the unit byte has historically been platform-dependent and has represented various storage sizes in the history of computing. Due to the influence of several major computer architectures and product lines, the byte became overwhelmingly associated with eight bits. This meaning of byte is codified in such standards as ISO/IEC 80000-13. |
Software Metrics Metamodel Measures Software_Metrics_Metamodel > Measures SMM specifies the representation of measures without detailing the representation of the entities measured. SMM defines representations for: Direct measures that are taken directly against a measurand. Examples include counts and named measures such as McCabe’s cyclomatic complexity or gross domestic product. Values may be imported or queried via SMM operations. |
Multistage amplifier Overall gain Cascade_amplifier > Overall gain The complication in calculating the gain of cascaded stages is the non-ideal coupling between stages due to loading. Two cascaded common emitter stages are shown. Because the input resistance of the second stage forms a voltage divider with the output resistance of the first stage, the total gain is not the product of the individual (separated) stages. The overall gain of a multistage amplifier is the product of the gains of the individual stages (ignoring potential loading effects): Gain (A) = A1* A2*A3 *A4 *... *An.Alternately, if the gain of each amplifier stage is expressed in decibels (dB), the total gain is the sum of the gains of the individual stages: Gain in dB (A) = A1 + A2 + A3 + A4 + ... An |
Variance-to-mean ratio Interpretation Variance-to-mean_ratio > Interpretation Some distributions, most notably the Poisson distribution, have equal variance and mean, giving them a VMR = 1. The geometric distribution and the negative binomial distribution have VMR > 1, while the binomial distribution has VMR < 1, and the constant random variable has VMR = 0. This yields the following table: This can be considered analogous to the classification of conic sections by eccentricity; see Cumulants of particular probability distributions for details. The relevance of the index of dispersion is that it has a value of 1 when the probability distribution of the number of occurrences in an interval is a Poisson distribution. |
The Compendious Book on Calculation by Completion and Balancing Quadratic equations The_Compendious_Book_on_Calculation_by_Completion_and_Balancing > Quadratic equations Repeated application of this rule eliminates negative quantities from calculations. Al-Muqabala (المقابله, "balancing" or "corresponding") means subtraction of the same positive quantity from both sides: "x2 + 5 = 40x + 4x2" is turned into "5 = 40x + 3x2". Repeated application of this rule makes quantities of each type ("square"/"root"/"number") appear in the equation at most once, which helps to see that there are only 6 basic solvable types of the problem, when restricted to positive coefficients and solutions. Subsequent parts of the book do not rely on solving quadratic equations. |
Organizational engineering Applications Organizational_engineering > Applications The various “I Opt” individual analyzes are used as a component of educational programs in areas like leadership development, learning and career guidance. They are also used to facilitate education itself. For example, the TwoPerson Analysis is used as a tool to quickly launch mentoring relationships. |
HIV envelope gp120 HIV_envelope > In HIV > gp120 Exposed on the surface of the viral envelope, the glycoprotein gp120 binds to the CD4 receptor on any target cell that has such a receptor, particularly the helper T-cell. Strains of HIV-1 have been isolated that are able to enter host cells that are CD4 negative. This CD4-independence is associated with spontaneous mutation in the env gene. |
Denitrifying bacteria Summary Denitrifying_bacteria Denitrifying bacteria are a diverse group of bacteria that encompass many different phyla. This group of bacteria, together with denitrifying fungi and archaea, is capable of performing denitrification as part of the nitrogen cycle. Denitrification is performed by a variety of denitrifying bacteria that are widely distributed in soils and sediments and that use oxidized nitrogen compounds in absence of oxygen as a terminal electron acceptor. They metabolise nitrogenous compounds using various enzymes, turning nitrogen oxides back to nitrogen gas ( N 2 {\displaystyle {\ce {N2}}} ) or nitrous oxide ( N 2 O {\displaystyle {\ce {N2O}}} ). |
Lebesgue integration Alternative formulations Lebesgue_integration > Alternative formulations The Riemann integral exists for any continuous function f of compact support defined on Rn (or a fixed open subset). Integrals of more general functions can be built starting from these integrals. Let Cc be the space of all real-valued compactly supported continuous functions of R. Define a norm on Cc by Then Cc is a normed vector space (and in particular, it is a metric space.) |
Simon's problem Summary Simon's_problem In computational complexity theory and quantum computing, Simon's problem is a computational problem that is proven to be solved exponentially faster on a quantum computer than on a classical (that is, traditional) computer. The quantum algorithm solving Simon's problem, usually called Simon's algorithm, served as the inspiration for Shor's algorithm. Both problems are special cases of the abelian hidden subgroup problem, which is now known to have efficient quantum algorithms. The problem is set in the model of decision tree complexity or query complexity and was conceived by Daniel Simon in 1994. |
K-25 Gaseous diffusion K-25 > Gaseous diffusion In a container with a porous barrier containing a mixture of two gases, the lighter molecules will pass out of the container more rapidly than the heavier molecules. The gas leaving the container is slightly enriched in the lighter molecules, while the residual gas is slightly depleted. A container wherein the enrichment process takes place through gaseous diffusion is called a diffuser.Gaseous diffusion had been used to separate isotopes before. |
Professional File System Summary Professional_File_System The Professional File System is a filesystem originally developed commercially for the Amiga, now distributed on Aminet with a 4-clause BSD license. It is a compatible successor of AmiFileSafe (AFS), with an emphasis on added reliability and speed compared to standard Amiga filesystems. It also features multi-user abilities like the older MuFS.The device is split into two main areas. At the beginning of the device is the metadata section, which consists of a root block, and a generic array of blocks that can be allocated to store metadata. |
Atmospheric turbulence Features Atmospheric_turbulence > Features In the best case, this assumption is only an approximation. Nevertheless, the turbulent diffusivity is the simplest approach for quantitative analysis of turbulent flows, and many models have been postulated to calculate it. |
Computation and Neural Systems Summary Computation_and_Neural_Systems The Computation and Neural Systems (CNS) program was established at the California Institute of Technology in 1986 with the goal of training Ph.D. students interested in exploring the relationship between the structure of neuron-like circuits/networks and the computations performed in such systems, whether natural or synthetic. The program was designed to foster the exchange of ideas and collaboration among engineers, neuroscientists, and theoreticians. |
Sucharit Bhakdi Atherosclerosis Sucharit_Bhakdi > Scientific and medical career > Research career > Atherosclerosis According to Bhakdi's hypothesis, LDL is generally not oxidized, but cholesterol is also absorbed by monocytes and foam cells are formed. However, the high density lipoprotein (HDL) can remove cholesterol again. If, however, a certain amount of LDL accumulates locally on the vascular wall and cannot be removed, part of the immune system causes inflammatory reactions that lead to atherosclerosis. In this way, early-stage atherosclerosis could be reversed if the LDL blood level (and blood pressure) was lowered and the HDL level increased. Bhakdi's hypothesis, however, is not reflected in current opinion. |
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