Split (1)

train · 253k rows

page_content stringlengths 51 3.15k
Transformer (machine learning model) Positional encoding Transformer_(neural_network) > Architecture > Encoder > Positional encoding A positional encoding is a fixed-size vector representation that encapsulates the relative positions of tokens within a target sequence: it provides the transformer model with information about where the words are in the input sequence. The positional encoding is defined as a function of type f: R → R d ; d ∈ Z , d > 0 {\displaystyle f:\mathbb {R} \to \mathbb {R} ^{d};d\in \mathbb {Z} ,d>0} , where d {\displaystyle d} is a positive even integer. The full positional encoding – as defined in the original paper – is given by the equation:where θ = t r k , r = N 2 / d {\displaystyle \theta ={\frac {t}{r^{k}}},r=N^{2/d}} . Here, N {\displaystyle N} is a free parameter that should be significantly larger than the biggest k {\displaystyle k} that would be input into the positional encoding function.
Max pooling Parameter sharing Pooling_(neural_networks) > Building blocks > Convolutional layer > Parameter sharing Therefore, it is common to refer to the sets of weights as a filter (or a kernel), which is convolved with the input. The result of this convolution is an activation map, and the set of activation maps for each different filter are stacked together along the depth dimension to produce the output volume. Parameter sharing contributes to the translation invariance of the CNN architecture.Sometimes, the parameter sharing assumption may not make sense.
P53 Interactions Tumor_suppressor_protein_p53 > Interactions p53 has been shown to interact with:
Pointe technique Movement into en pointe Pointe_technique > Technique > Movement into en pointe In the process, the feet break contact with the floor and the dancer is briefly airborne. To transition to en pointe via piqué, a dancer will step out directly onto a fully extended, vertical foot. The other foot is then raised from the floor, thereby leaving the dancer en pointe.
Hothouse Earth Greenhouse Earth Greenhouse_and_icehouse_Earth > Greenhouse Earth A "greenhouse Earth" is a period during which no continental glaciers exist anywhere on the planet. Additionally, the levels of carbon dioxide and other greenhouse gases (such as water vapor and methane) are high, and sea surface temperatures (SSTs) range from 28 °C (82.4 °F) in the tropics to 0 °C (32 °F) in the polar regions. Earth has been in a greenhouse state for about 85% of its history.The state should not be confused with a hypothetical runaway greenhouse effect, which is an irreversible tipping point that corresponds to the ongoing runaway greenhouse effect on Venus. The IPCC states that "a 'runaway greenhouse effect'—analogous to Venus—appears to have virtually no chance of being induced by anthropogenic activities."
Measure of central tendency Uniqueness Measure_of_central_tendency > Solutions to variational problems > Uniqueness The mean (L2 center) and midrange (L∞ center) are unique (when they exist), while the median (L1 center) and mode (L0 center) are not in general unique. This can be understood in terms of convexity of the associated functions (coercive functions). The 2-norm and ∞-norm are strictly convex, and thus (by convex optimization) the minimizer is unique (if it exists), and exists for bounded distributions. Thus standard deviation about the mean is lower than standard deviation about any other point, and the maximum deviation about the midrange is lower than the maximum deviation about any other point.
Dialectics of Nature History and contents Marxist_philosophy_of_nature > History and contents "Their interest lies not so much in their detailed criticism of theories, but in showing how Engels grappled with intellectual problems". One "law" proposed in the Dialectics of Nature is the "law of the transformation of quantity into quality and vice versa". Probably the most commonly cited example of this is the change of water from a liquid to a gas, by increasing its temperature (although Engels also describes other examples from chemistry).
Bundle conductor Circuits Bundle_conductor > Structures > Circuits Single phase AC-power lines as used for traction current have four conductors for two circuits. Usually both circuits operate at the same voltage. In HVDC systems typically two conductors are carried per line, but in rare cases only one pole of the system is carried on a set of towers.
Concrete syntax Nomenclature Concrete_syntax > Nomenclature A parse tree is made up of nodes and branches. In the picture the parse tree is the entire structure, starting from S and ending in each of the leaf nodes (John, ball, the, hit). In a parse tree, each node is either a root node, a branch node, or a leaf node. In the above example, S is a root node, NP and VP are branch nodes, while John, ball, the, and hit are all leaf nodes.
Analog electronics Noise Analog_circuits > Analogue vs digital electronics > Noise Analogue signals can still contain intelligible information with very high levels of noise. Digital circuits, on the other hand, are not affected at all by the presence of noise until a certain threshold is reached, at which point they fail catastrophically. For digital telecommunications, it is possible to increase the noise threshold with the use of error detection and correction coding schemes and algorithms.
Volatility (finance) Mathematical definition Volatility_(finance) > Mathematical definition A common assumption is that P = 252 trading days in any given year. Then, if σdaily = 0.01, the annualized volatility is σ annually = 0.01 252 = 0.1587. {\displaystyle \sigma _{\text{annually}}=0.01{\sqrt {252}}=0.1587.}
Nuclear Chemistry Biology Nuclear_Chemistry > Spinout areas > Uses within geology, biology and forensic science > Biology Stable isotopes have the advantage of not delivering a radiation dose to the system being studied; however, a significant excess of them in the organ or organism might still interfere with its functionality, and the availability of sufficient amounts for whole-animal studies is limited for many isotopes. Measurement is also difficult, and usually requires mass spectrometry to determine how much of the isotope is present in particular compounds, and there is no means of localizing measurements within the cell. 2H (deuterium), the stable isotope of hydrogen, is a stable tracer, the concentration of which can be measured by mass spectrometry or NMR.
Communicative ecology Dimensions Communicative_ecology > Characteristics > Dimensions They may also consider how different media may facilitate or constrain either networked or collective interaction. If interested in the global or local characteristics of an ecology, researchers may examine how communication with proximate others may be mediated differently from communication with others in distant locales. They could also explore which communication topics are more likely to occur at the local level rather than within globally distributed social networks.
Automotive electronics Engine electronics Automotive_electronics > Types > Engine electronics One of the most demanding electronic parts of an automobile is the engine control unit (ECU). Engine controls demand one of the highest real-time deadlines, as the engine itself is a very fast and complex part of the automobile. Of all the electronics in any car, the computing power of the engine control unit is the highest, typically a 32-bit processor.A modern car may have up to 100 ECU's and a commercial vehicle up to 40.An engine ECU controls such functions as: In a diesel engine: Fuel injection rate Emission control, NOx control Regeneration of oxidation catalytic converter Turbocharger control Cooling system control Throttle controlIn a gasoline engine: Lambda control OBD (On-Board Diagnostics) Cooling system control Ignition system control Lubrication system control (only a few have electronic control) Fuel injection rate control Throttle controlMany more engine parameters are actively monitored and controlled in real-time.
Skyline operator Summary Skyline_operator The skyline operator is the subject of an optimization problem, used in a query to filter results from a database to keep only those objects that are not worse than any other. This operator is an extension to SQL proposed by Börzsönyi et al. A classic example of application of the skyline operator involves selecting a hotel for a holiday. The user wants the hotel to be both cheap and close to the beach. However, hotels that are close to the beach may also be expensive. In this case, the skyline operator would only present those hotels that are not worse than any other hotel in both price and distance to the beach.
Size zero Movement against size zero Size_zero > Movement against size zero Their law stipulates that women and men hired as models must be certified by a physician as having a body mass index (BMI) of no less than 18.5. The legislation also requires the inclusion of an informational note in adverts using photos manipulated to make models look thinner. There were divergent views on the ban within the Israeli fashion industry. One modelling agent, who had helped promote the bill, suggested that the fall in typical dress sizes for models in the preceding 15–20 years amounted to "the difference between death and life". However, another described the law as "arbitrary" and "not appropriate for every model".
Magnetite Magnetene Magnetite > Magnetene Magnetene is a 2 dimensional flat sheet of magnetite noted for its ultra-low-friction behavior.
Bull market Summary Bull_market A market trend is a perceived tendency of financial markets to move in a particular direction over time. Analysts classify these trends as secular for long time-frames, primary for medium time-frames, and secondary for short time-frames. Traders attempt to identify market trends using technical analysis, a framework which characterizes market trends as predictable price tendencies within the market when price reaches support and resistance levels, varying over time. A market trend can only be determined in hindsight, since at any time prices in the future are not known.
Group dynamics Group structure Group_dynamics > Intragroup dynamics > Group structure Centralized communications allow standardization of information, but may restrict the free flow of information. Decentralized communications make it easy to share information directly between group members. When decentralized, communications tend to flow more freely, but the delivery of information may not be as fast or accurate as with centralized communications.
Thermal physics Overview Thermal_physics > Overview Thermal physics, generally speaking, is the study of the statistical nature of physical systems from an energetic perspective. Starting with the basics of heat and temperature, thermal physics analyzes the first law of thermodynamics and second law of thermodynamics from the statistical perspective, in terms of the number of microstates corresponding to a given macrostate. In addition, the concept of entropy is studied via quantum theory. A central topic in thermal physics is the canonical probability distribution.
Natural language programming Software paradigm Natural-language_programming > Software paradigm Natural-language programming is a top-down method of writing software. Its stages are as follows: Definition of an ontology – taxonomy – of concepts needed to describe tasks in the topic addressed. Each concept and all their attributes are defined in natural-language words. This ontology will define the data structures the NLP can use in sentences.
Cognitive dissonance Forbidden behavior paradigm Cognitive_dissonance > Paradigms > Induced compliance > Forbidden behavior paradigm After playing alone, the control-group children later devalued the importance of the forbidden toy. In the variable group, classical music played in the background while the children played alone.
Linear seismic inversion Summary Linear_seismic_inversion Inverse modeling is a mathematical technique where the objective is to determine the physical properties of the subsurface of an earth region that has produced a given seismogram. Cooke and Schneider (1983) defined it as calculation of the earth's structure and physical parameters from some set of observed seismic data. The underlying assumption in this method is that the collected seismic data are from an earth structure that matches the cross-section computed from the inversion algorithm. Some common earth properties that are inverted for include acoustic velocity, formation and fluid densities, acoustic impedance, Poisson's ratio, formation compressibility, shear rigidity, porosity, and fluid saturation.
Thermochemical cycle Water-splitting via a single reaction Thermochemical_cycle > Principles > Water-splitting via a single reaction Consider a system composed of chemical species (e.g. water splitting) in thermodynamic equilibrium at constant pressure and thermodynamic temperature T: H2O(l) ⇌ {\displaystyle \rightleftharpoons } H2(g) + 1/2 O2(g) (1)Equilibrium is displaced to the right only if energy (enthalpy change ΔH for water-splitting) is provided to the system under strict conditions imposed by thermodynamics: one fraction must be provided as work, namely the Gibbs free energy change ΔG of the reaction: it consists of "noble" energy, i.e. under an organized state where matter can be controlled, such as electricity in the case of the electrolysis of water. Indeed, the generated electron flow can reduce protons (H+) at the cathode and oxidize anions (O2−) at the anode (the ions exist because of the chemical polarity of water), yielding the desired species. the other one must be supplied as heat, i.e. by increasing the thermal agitation of the species, and is equal by definition of the entropy to the absolute temperature T times the entropy change ΔS of the reaction. Δ H = Δ G + T Δ S {\displaystyle \Delta H=\Delta G+T\Delta S} (2)Hence, for an ambient temperature T° of 298K (kelvin) and a pressure of 1 atm (atmosphere (unit)) (ΔG° and ΔS° are respectively equal to 237 kJ/mol and 163 J/mol/K, relative to the initial amount of water), more than 80% of the required energy ΔH must be provided as work in order for water-splitting to proceed.
Ehrenfest paradox Essence of the paradox Ehrenfest_paradox > Essence of the paradox However, since the radius is perpendicular to the direction of motion, it will not undergo any contraction. So c i r c u m f e r e n c e d i a m e t e r = 2 π R 1 − ( ω R ) 2 / c 2 2 R = π 1 − ( ω R ) 2 / c 2 . {\displaystyle {\frac {\mathrm {circumference} }{\mathrm {diameter} }}={\frac {2\pi R{\sqrt {1-(\omega R)^{2}/c^{2}}}}{2R}}=\pi {\sqrt {1-(\omega R)^{2}/c^{2}}}.} This is paradoxical, since in accordance with Euclidean geometry, it should be exactly equal to π.
Ω-consistent theory Definition Ω-consistent_theory > Definition If the language of T consists only of the language of arithmetic (as opposed to, for example, set theory), then a sound system is one whose model can be thought of as the set ω, the usual set of mathematical natural numbers. The case of general T is different, see ω-logic below. Σn-soundness has the following computational interpretation: if the theory proves that a program C using a Σn−1-oracle halts, then C actually halts.
Reference model The uses of a reference model Reference_model > The uses of a reference model A third use of a reference model is to improve communication between people. A reference model breaks up a problem into entities, or "things that exist all by themselves." This is often an explicit recognition of concepts that many people already share, but when created in an explicit manner, a reference model is useful by defining how these concepts differ from, and relate to, one another.
Crowdsensing Process Crowdsensing > Process The second stage involves the storage of data in the user's device until it gets another user to share and communicate. For instance, videos monitoring an activity (e.g. traffic) may be stored on a user's device for a specific period and are then transmitted to a person or institution capable of taking action.An example of mobile crowdsensing is when mobile phone users activate the mobile sensor, including Google Maps and Snapchat that collect and share local information to the internet. The app retrieves information such as location, birthday, gender, and more.
Active suspension Magnetorheological damper Active_suspension > Adaptive and semi-active > Magnetorheological damper The damper fluid contains metallic particles. Through the onboard computer, the dampers' compliance characteristics are controlled by an electromagnet. Essentially, increasing the current flow into the damper magnetic circuit increases the circuit magnetic flux.
Empirical dynamic modeling Convergent Cross Mapping Empirical_dynamic_modeling > Methods > Convergent Cross Mapping Convergent cross mapping (CCM) leverages a corollary to the Generalized Takens Theorem that it should be possible to cross predict or cross map between variables observed from the same system. Suppose that in some dynamical system involving variables X {\displaystyle X} and Y {\displaystyle Y} , X {\displaystyle X} causes Y {\displaystyle Y} . Since X {\displaystyle X} and Y {\displaystyle Y} belong to the same dynamical system, their reconstructions (via embeddings) M x {\displaystyle M_{x}} , and M y {\displaystyle M_{y}} , also map to the same system. The causal variable X {\displaystyle X} leaves a signature on the affected variable Y {\displaystyle Y} , and consequently, the reconstructed states based on Y {\displaystyle Y} can be used to cross predict values of X {\displaystyle X} . CCM leverages this property to infer causality by predicting X {\displaystyle X} using the M y {\displaystyle M_{y}} library of points (or vice versa for the other direction of causality), while assessing improvements in cross map predictability as larger and larger random samplings of M y {\displaystyle M_{y}} are used. If the prediction skill of X {\displaystyle X} increases and saturates as the entire M y {\displaystyle M_{y}} is used, this provides evidence that X {\displaystyle X} is casually influencing Y {\displaystyle Y} .
Digital library Searching Digital_library > Features of digital libraries > Searching A drawback to this approach is that the search mechanism is limited by the different indexing and ranking capabilities of each database; therefore, making it difficult to assemble a combined result consisting of the most relevant found items. Searching over previously harvested metadata involves searching a locally stored index of information that has previously been collected from the libraries in the federation. When a search is performed, the search mechanism does not need to make connections with the digital libraries it is searching—it already has a local representation of the information.
Environmental stress Biological background Stress_(biology) > Biological background Stress can have many profound effects on the human biological systems. Biology primarily attempts to explain major concepts of stress using a stimulus-response paradigm, broadly comparable to how a psychobiological sensory system operates. The central nervous system (brain and spinal cord) plays a crucial role in the body's stress-related mechanisms. Whether one should interpret these mechanisms as the body's response to a stressor or embody the act of stress itself is part of the ambiguity in defining what exactly stress is.
Painting and Decorating Contractors of America Industry leadership Painting_and_Decorating_Contractors_of_America > Industry leadership PCA has connected with a variety of groups to provide services to the painting and decorating profession. Some examples of these initiatives have focused on improving occupational safety and health, and the role of women in painting
Embodied cognition Memory Embodied_cognition > Scope > Memory The relationships between memory and embodied cognition have been demonstrated in studies in different fields and through various tasks. In general, studies on embodied cognition and memory investigate how manipulations on the body cause changes in memory performance, or vice versa, manipulations through memory tasks subsequently lead to bodily changes. Researchers has drawn attention to the relationship between memory and action from an embodied cognition approach where memory is defined as integrated patterns of actions limited by the body.
One-way encryption Universal one-way function One-way_functions > Universal one-way function There is an explicit function f that has been proved to be one-way, if and only if one-way functions exist. In other words, if any function is one-way, then so is f. Since this function was the first combinatorial complete one-way function to be demonstrated, it is known as the "universal one-way function". The problem of finding a one-way function is thus reduced to proving—perhaps non-constructively—that one such function exists.
Glossary of power electronics I Glossary_of_power_electronics > I indirect current link AC converter An AC converter with a current stiff DC link . indirect DC converter A DC converter with an AC link. indirect inverter An inverter with a DC link.
Nuclear Magnetic Resonance Fourier-transform spectroscopy Nuclear_Magnetic_Resonance > NMR spectroscopy > Fourier-transform spectroscopy In order to obtain the frequency-domain NMR spectrum (NMR absorption intensity vs. NMR frequency) this time-domain signal (intensity vs. time) must be Fourier transformed. Fortunately, the development of Fourier transform (FT) NMR coincided with the development of digital computers and the digital fast Fourier transform (FFT). Fourier methods can be applied to many types of spectroscopy. Richard R. Ernst was one of the pioneers of pulsed NMR and won a Nobel Prize in chemistry in 1991 for his work on Fourier Transform NMR and his development of multi-dimensional NMR spectroscopy.
Philosophy of time Causation solution Philosophy_of_time > Direction of time > Causation solution One solution to this problem takes a metaphysical view, in which the direction of time follows from an asymmetry of causation. We know more about the past because the elements of the past are causes for the effect that is our perception. We feel we can't affect the past and can affect the future because we can't affect the past and can affect the future. There are two main objections to this view.
Algorithm characterizations 1954 A. A. Markov Jr.'s characterization Algorithm_characterization > 1954 A. A. Markov Jr.'s characterization We replace this by a physical limitation which we call the principle of local causation. Its justification lies in the finite velocity of propagation of effects and signals: contemporary physics rejects the possibility of instantaneous action at a distance." (Gandy (1980) p. 135 in J. Barwise et al.)
Rodrigues' rotation formula Matrix notation Rodrigues'_rotation_formula > Matrix notation The linear transformation on v ∈ R 3 {\displaystyle \mathbf {v} \in \mathbb {R} ^{3}} defined by the cross product v ↦ k × v {\displaystyle \mathbf {v} \mapsto \mathbf {k} \times \mathbf {v} } is given in coordinates by representing v and k × v as column matrices: = = . {\displaystyle {\begin{bmatrix}(\mathbf {k} \times \mathbf {v} )_{x}\\(\mathbf {k} \times \mathbf {v} )_{y}\\(\mathbf {k} \times \mathbf {v} )_{z}\end{bmatrix}}={\begin{bmatrix}k_{y}v_{z}-k_{z}v_{y}\\k_{z}v_{x}-k_{x}v_{z}\\k_{x}v_{y}-k_{y}v_{x}\end{bmatrix}}=\left{\begin{bmatrix}v_{x}\\v_{y}\\v_{z}\end{bmatrix}}\,.} That is, the matrix of this linear transformation (with respect to standard coordinates) is the cross-product matrix: K = .
Refectory table Summary Refectory_table A refectory table is a highly elongated table used originally for dining in monasteries during Medieval times. In the Late Middle Ages, the table gradually became a banqueting or feasting table in castles and other noble residences. The original table manufacture was by hand and created of oak or walnut; the design is based on a trestle style. Typically, the table legs are supported by circumferential stretchers positioned very low to the floor.
GIS in archaeology GIS in analysis GIS_in_archaeology > GIS in analysis Simulation is a simplified representation of reality, attempting to model phenomena by identifying key variables and their interactions. This is used to think through problem formulation, as a means of testing hypothetical predictions, and also as a means to generate data.
Vector spherical harmonics Summary Vector_spherical_harmonics In mathematics, vector spherical harmonics (VSH) are an extension of the scalar spherical harmonics for use with vector fields. The components of the VSH are complex-valued functions expressed in the spherical coordinate basis vectors.
Likelihood ratio Example Log_likelihood > Definition > Discrete probability distribution > Example Consider a simple statistical model of a coin flip: a single parameter p H {\displaystyle p_{\text{H}}} that expresses the "fairness" of the coin. The parameter is the probability that a coin lands heads up ("H") when tossed. p H {\displaystyle p_{\text{H}}} can take on any value within the range 0.0 to 1.0. For a perfectly fair coin, p H = 0.5 {\displaystyle p_{\text{H}}=0.5} .
Affinity propagation Applications Affinity_propagation > Applications The inventors of affinity propagation showed it is better for certain computer vision and computational biology tasks, e.g. clustering of pictures of human faces and identifying regulated transcripts, than k-means, even when k-means was allowed many random restarts and initialized using PCA. A study comparing affinity propagation and Markov clustering on protein interaction graph partitioning found Markov clustering to work better for that problem. A semi-supervised variant has been proposed for text mining applications. Another recent application was in economics, when the affinity propagation was used to find some temporal patterns in the output multipliers of the US economy between 1997 and 2017.
QED vacuum Attainability QED_vacuum > Attainability Predictions of QED vacuum such as spontaneous emission, the Casimir effect and the Lamb shift have been experimentally verified, suggesting QED vacuum is a good model for a high quality realizable vacuum. There are competing theoretical models for vacuum, however. For example, quantum chromodynamic vacuum includes many virtual particles not treated in quantum electrodynamics. The vacuum of quantum gravity treats gravitational effects not included in the Standard Model. It remains an open question whether further refinements in experimental technique ultimately will support another model for realizable vacuum.
Introduction to viruses Innate immunity of animals Introduction_to_viruses > Viruses and diseases > Host resistance > Innate immunity of animals Animals, including humans, have many natural defences against viruses. Some are non-specific and protect against many viruses regardless of the type. This innate immunity is not improved by repeated exposure to viruses and does not retain a "memory" of the infection. The skin of animals, particularly its surface, which is made from dead cells, prevents many types of viruses from infecting the host.
Theory of equations Summary Theory_of_equations In algebra, the theory of equations is the study of algebraic equations (also called "polynomial equations"), which are equations defined by a polynomial. The main problem of the theory of equations was to know when an algebraic equation has an algebraic solution. This problem was completely solved in 1830 by Évariste Galois, by introducing what is now called Galois theory.
7178 aluminium alloy Advantages 7178_aluminium_alloy > Advantages High corrosion resistance High tensile strength Excellent polish High machine strength High creep resistance High temperature strength High mechanical properties
Evolutionary rescue Theoretical framework Evolutionary_rescue > Theoretical framework After a sudden change in the environment, evolutionary rescue is predicted to create a U-shaped curve of population dynamics, as the original genotypes, which are unable to replace themselves, are replaced by genotypes that are able to increase in numbers. In a continuously changing environment, evolutionary rescue is predicted to appear as a stable lag of the mean trait value behind a moving environmental optimum, where the rate of evolution and rate of change in the environment are equal. The theory has been reviewed by Alexander et al in 2014 and continues to grow rapidly, adding both genetic and ecological complexity. Evolutionary rescue is distinct from demographic rescue, where a population is sustained by continuous migration from elsewhere, without the need for evolution. On the other hand, genetic rescue, where a population persists because of migration that reduces inbreeding depression, can be thought of a special case of evolutionary rescue (but see ).
Blockchain technology Domain names Hybrid_blockchains > Uses > Domain names There are several different efforts to offer domain name services via the blockchain. These domain names can be controlled by the use of a private key, which purports to allow for uncensorable websites. This would also bypass a registrar's ability to suppress domains used for fraud, abuse, or illegal content.Namecoin is a cryptocurrency that supports the ".bit" top-level domain (TLD). Namecoin was forked from bitcoin in 2011.
Edward Thorndike Adult learning Edward_Thorndike > Adult learning Identifiability- According to Thorndike, the identification or placement of a situation is a first response of the nervous system, which can recognize it. Then connections may be made to one another or to another response, and these connections depend upon the original identification. Therefore, a large amount of learning is made up of changes in the identifiability of situations.
IR spectrum Practical IR spectroscopy Infra-red_spectroscopy > Practical IR spectroscopy Alternatively, the entire wavelength range is measured using a Fourier transform instrument and then a transmittance or absorbance spectrum is generated using a dedicated procedure. This technique is commonly used for analyzing samples with covalent bonds. Simple spectra are obtained from samples with few IR active bonds and high levels of purity. More complex molecular structures lead to more absorption bands and more complex spectra.
Black Hole General relativity Black_Holes > History > General relativity Firstly, the force of gravitation would be so great that light would be unable to escape from it, the rays falling back to the star like a stone to the earth. Secondly, the red shift of the spectral lines would be so great that the spectrum would be shifted out of existence. Thirdly, the mass would produce so much curvature of the spacetime metric that space would close up around the star, leaving us outside (i.e., nowhere).
Overdiagnosis Overdiagnosis and the variability of cancer progression Overdiagnosis > Overdiagnosis and the variability of cancer progression In other words, there are cellular abnormalities that meet the pathologic definition of cancer but never grow to cause symptoms—alternatively, they may grow and then regress. Although the concept of non-progressive cancers may seem implausible, basic scientists have begun to uncover biologic mechanisms that halt the progression of cancer. Some cancers outgrow their blood supply (and are starved), others are recognized by the host's immune system (and are successfully contained), and some are not that aggressive in the first place. Cancer that grows too slowly to be likely to harm the patient is usually referred to as a benign tumor. Although some types of benign tumor may require intervention, they are often simply monitored for malignant transformation.
Homocitrate synthase Summary Homocitrate_synthase In enzymology, a homocitrate synthase (EC 2.3.3.14) is an enzyme that catalyzes the chemical reaction acetyl-CoA + H2O + 2-oxoglutarate ⇌ {\displaystyle \rightleftharpoons } (R)-2-hydroxybutane-1,2,4-tricarboxylate + CoAThe 3 substrates of this enzyme are acetyl-CoA, H2O, and 2-oxoglutarate, whereas its two products are (R)-2-hydroxybutane-1,2,4-tricarboxylate and CoA. This enzyme belongs to the family of transferases, specifically those acyltransferases that convert acyl groups into alkyl groups on transfer. The systematic name of this enzyme class is acetyl-CoA:2-oxoglutarate C-acetyltransferase (thioester-hydrolysing, carboxymethyl forming). Other names in common use include 2-hydroxybutane-1,2,4-tricarboxylate 2-oxoglutarate-lyase, (CoA-acetylating), acetyl-coenzyme A:2-ketoglutarate C-acetyl transferase, and homocitrate synthetase. This enzyme participates in lysine biosynthesis and pyruvate metabolism.
Neurophilosophy Views on computation Neurophilosophy > Computation and representation in the brain > Views on computation Shagrir identifies several philosophers of neuroscience who espouse structural accounts. According to him, Fodor and Pylyshyn require some sort of syntactic constraint on their theory of computation. This is consistent with their rejection of connectionist systems on the grounds of systematicity.
Rigid bodies Linear and angular velocity Rigid_Body > Kinematics > Linear and angular velocity However, when motion involves rotation, the instantaneous velocity of any two points on the body will generally not be the same. Two points of a rotating body will have the same instantaneous velocity only if they happen to lie on an axis parallel to the instantaneous axis of rotation. Angular velocity is a vector quantity that describes the angular speed at which the orientation of the rigid body is changing and the instantaneous axis about which it is rotating (the existence of this instantaneous axis is guaranteed by the Euler's rotation theorem).
Non-communicable diseases Diabetes Noncommunicable_diseases > Key diseases > Diabetes Type 2 Diabetes Mellitus is a chronic condition which is largely preventable and manageable but difficult to cure. Management concentrates on keeping blood sugar levels as close to normal ("euglycemia") as possible without presenting undue patient danger. This can usually be with close dietary management, exercise, and use of appropriate medications (insulin only in the case of type 1 diabetes mellitus. Oral medications may be used in the case of type 2 diabetes, as well as insulin).
Kepler-371 Summary Kepler-371 Kepler-371 (also known as KOI-2194 or KIC 3548044) is a star some 2,720 ly away from the Earth. It hosts a multi planetary system consisting of 2 confirmed Super-Earths, as well as 1 unconfirmed Near-Earth sized exoplanet in its habitable zone. == References ==
Scientific Notation Normalized notation Scientific_Notation > Normalized notation It is also the form that is required when using tables of common logarithms. In normalized notation, the exponent n is negative for a number with absolute value between 0 and 1 (e.g. 0.5 is written as 5×10−1). The 10 and exponent are often omitted when the exponent is 0.
B vitamins Related compounds Vitamin_B_complex > Related compounds Isolated from human urine at 0.33ppm (later in blood), but later abandoned by him as further evidence did not confirm this. He also claimed this was not xanthopterin. Vitamin B15: pangamic acid, also known as pangamate.
Disulfur tetrafluoride Summary Disulfur_tetrafluoride 1,1,1,2-tetrafluorodisulfane, also known as 1,2-difluorodisulfane 1,1-difluoride or just difluorodisulfanedifluoride (FSSF3) is an unstable molecular compound of fluorine and sulfur. The molecule has a pair of sulfur atoms, with one fluorine atom on one sulfur, and three fluorine atoms on the other. It has the uncommon property that all the bond lengths are different. The bond strength is not correlated with bond length but is inversely correlated with the force constant (Badger's rule).
Strong CP problem Proposed solutions Strong_CP_problem > Proposed solutions The axion ground state dynamically forces the theory to be CP-symmetric by setting θ ¯ = 0 {\displaystyle {\bar {\theta }}=0} . Axions are also considered viable candidates for dark matter and axion-like particles are also predicted by string theory. Other less popular proposed solutions exist such as Nelson–Barr models. These set θ ¯ = 0 {\displaystyle {\bar {\theta }}=0} at some high energy scale where CP-symmetry is exact but the symmetry is then spontaneously broken at low energies. The tricky part of these models is to account for why θ ¯ {\displaystyle {\bar {\theta }}} remains small at low energies while the CP breaking phase in the CKM matrix becomes large.
Relational Database Relations or tables Relational_database_management_systems > Relations or tables Similarly, queries identify tuples for updating or deleting. Tuples by definition are unique. If the tuple contains a candidate or primary key then obviously it is unique; however, a primary key need not be defined for a row or record to be a tuple. The definition of a tuple requires that it be unique, but does not require a primary key to be defined. Because a tuple is unique, its attributes by definition constitute a superkey.
Flatbed plotter Overview Pen_plotter > Overview Digitally controlled plotters evolved from earlier fully analog XY-writers used as output devices for measurement instruments and analog computers. Pen plotters print by moving a pen or other instrument across the surface of a piece of paper. This means that plotters are vector graphics devices, rather than raster graphics as with other printers. Pen plotters can draw complex line art, including text, but do so slowly because of the mechanical movement of the pens.
Mir-26 microRNA precursor family miR-26b roles Mir-26_microRNA_precursor_family > miR-26b roles Alongside other phosphatases, CTDSPs make up important components of a REST (repressor element 1 silencing transcription factor)/NRSF (neuron-restrictive silencer factor) protein complex. This REST/NRSF complex controls activation of the genes in turn responsible for control of neural stem cell differentiation.
Lebesgue integrability condition Examples Riemann_integrability > Examples Then, by carefully choosing the new tags, we can make the value of the Riemann sum turn out to be within ε of either zero or one. Our first step is to cut up the partition. There are n of the ti, and we want their total effect to be less than ε. If we confine each of them to an interval of length less than ε/n, then the contribution of each ti to the Riemann sum will be at least 0 · ε/n and at most 1 · ε/n.
Stack-based memory allocation System interface Stack-based_memory_allocation > System interface Many Unix-like systems as well as Microsoft Windows implement a function called alloca for dynamically allocating stack memory in a way similar to the heap-based malloc. A compiler typically translates it to inlined instructions manipulating the stack pointer, similar to how variable-length arrays are handled. Although there is no need to explicitly free the memory, there is a risk of undefined behavior due to stack overflow.
Bacterial recombination Evolution Bacterial_recombination > Evolution This clonal nature leads to random mutations that occur during DNA replication that potentially helps bacteria evolve. It was originally thought that only accumulated mutations helped bacteria evolve. In contrast, bacteria also import genes in a process called homologous recombination, first discovered by the observation of mosaic genes at loci encoding antibiotic resistance.
Logic of relatives Classes of signs Logic_of_relatives > Philosophy > Signs > Classes of signs Rheme, dicisign, argument (also called sumisign, dicisign, suadisign, also seme, pheme, delome, and regarded as very broadened versions of the traditional term, proposition, argument): This typology classifies every sign according to the category which the interpretant attributes to the sign's way of denoting its object—the rheme, for example a term, is a sign interpreted to represent its object in respect of quality; the dicisign, for example a proposition, is a sign interpreted to represent its object in respect of fact; and the argument is a sign interpreted to represent its object in respect of habit or law. This is the culminating typology of the three, where the sign is understood as a structural element of inference. Every sign belongs to one class or another within (I) and within (II) and within (III).
Gram-positive bacterium Exceptions Gram_positive_bacteria > Importance of the outer cell membrane in bacterial classification > Exceptions Two related phyla to the Chloroflexi, the TM7 clade and the Ktedonobacteria, are also monoderms.Some Bacillota species are not gram-positive. The class Negativicutes, which includes Selenomonas, are diderm and stain gram-negative. Additionally, a number of bacterial taxa (viz. Negativicutes, Fusobacteriota, Synergistota, and Elusimicrobiota) that are either part of the phylum Bacillota or branch in its proximity are found to possess a diderm cell structure. However, a conserved signature indel (CSI) in the HSP60 (GroEL) protein distinguishes all traditional phyla of gram-negative bacteria (e.g., Pseudomonadota, Aquificota, Chlamydiota, Bacteroidota, Chlorobiota, "Cyanobacteria", Fibrobacterota, Verrucomicrobiota, Planctomycetota, Spirochaetota, Acidobacteriota, etc.) from these other atypical diderm bacteria, as well as other phyla of monoderm bacteria (e.g., Actinomycetota, Bacillota, Thermotogota, Chloroflexota, etc.). The presence of this CSI in all sequenced species of conventional LPS (lipopolysaccharide)-containing gram-negative bacterial phyla provides evidence that these phyla of bacteria form a monophyletic clade and that no loss of the outer membrane from any species from this group has occurred.
Lunar habitation Energy storage Lunar_habitation > Energy > Solar energy > Energy storage Combining fuel cells with electrolysis would provide a "perpetual" source of electricity – solar energy could be used to provide power during the lunar day, and fuel cells at night. During the lunar day, solar energy would also be used to electrolyze the water created in the fuel cells – although there would be small losses of gases that would have to be replaced. Even if lunar facilities could provide themselves access to a near-continuous source of solar energy, they would still need to maintain fuel cells or an alternate energy storage system to sustain themselves during lunar eclipses and emergency situations.
Memory consolidation Synaptic consolidation Memory_consolidation > Synaptic consolidation It is also referred to as 'initial consolidation'. As soon as six hours after training, memories become impervious to interferences that disrupt synaptic consolidation and the formation of long-term memory. Late-phase LTP, the long-lasting form of one of the best understood forms of synaptic plasticity, is thought to be the cellular process underlying synaptic consolidation.
Clinical diagnosis Medical uses Clinical_diagnosis > Medical uses A complaint expressed by a patient. The fact that a patient has sought a diagnostician can itself be an indication to perform a diagnostic procedure. For example, in a doctor's visit, the physician may already start performing a diagnostic procedure by watching the gait of the patient from the waiting room to the doctor's office even before she or he has started to present any complaints.Even during an already ongoing diagnostic procedure, there can be an indication to perform another, separate, diagnostic procedure for another, potentially concomitant, disease or condition. This may occur as a result of an incidental finding of a sign unrelated to the parameter of interest, such as can occur in comprehensive tests such as radiological studies like magnetic resonance imaging or blood test panels that also include blood tests that are not relevant for the ongoing diagnosis.
Seismic tomography History Seismic_tomography > History Seismic tomography requires large datasets of seismograms and well-located earthquake or explosion sources. These became more widely available in the 1960s with the expansion of global seismic networks, and in the 1970s when digital seismograph data archives were established. These developments occurred concurrently with advancements in computing power that were required to solve inverse problems and generate theoretical seismograms for model testing.In 1977, P-wave delay times were used to create the first seismic array-scale 2D map of seismic velocity. In the same year, P-wave data were used to determine 150 spherical harmonic coefficients for velocity anomalies in the mantle.
Stack canary Exploiting stack buffer overflows Stack_based_buffer_overflow > Exploiting stack buffer overflows A twelve-character input thus requires thirteen bytes to store, the input followed by the sentinel zero byte. The zero byte then ends up overwriting a memory location that's one byte beyond the end of the buffer.) The program stack in foo() with various inputs: In figure C above, when an argument larger than 11 bytes is supplied on the command line foo() overwrites local stack data, the saved frame pointer, and most importantly, the return address.
Scale-invariant feature transform Keypoint descriptor Scale-invariant_feature_transform > Algorithm > Keypoint descriptor The threshold of 0.2 was empirically chosen, and by replacing the fixed threshold with one systematically calculated, matching results can be improved.Although the dimension of the descriptor, i.e. 128, seems high, descriptors with lower dimension than this don't perform as well across the range of matching tasks and the computational cost remains low due to the approximate BBF (see below) method used for finding the nearest neighbor. Longer descriptors continue to do better but not by much and there is an additional danger of increased sensitivity to distortion and occlusion. It is also shown that feature matching accuracy is above 50% for viewpoint changes of up to 50 degrees. Therefore, SIFT descriptors are invariant to minor affine changes. To test the distinctiveness of the SIFT descriptors, matching accuracy is also measured against varying number of keypoints in the testing database, and it is shown that matching accuracy decreases only very slightly for very large database sizes, thus indicating that SIFT features are highly distinctive.
Vmsplice() local root exploit Architecture and features Vmsplice()_local_root_exploit > Architecture and features Configurable I/O schedulers, ioctl(2) syscall that manipulates the underlying device parameters of special files (it is a non standard system call, since arguments, returns, and semantics depends on the device driver in question), support for POSIX asynchronous I/O (however, because they scale poorly with multithreaded applications, a family of Linux specific I/O system calls (io_*(2)) had to be created for the management of asynchronous I/O contexts suitable for concurrently processing). OS-level virtualization (with Linux-VServer), paravirtualization and hardware-assisted virtualization (with KVM or Xen, and using QEMU for hardware emulation); On the Xen hypervisor, the Linux kernel provides support to build Linux distributions (such as openSuSE Leap and many others) that work as Dom0, that are virtual machine host servers that provide the management environment for the user's virtual machines (DomU). I/O Virtualization with VFIO and SR-IOV.
Hirayama disease Diagnosis Hirayama_disease > Diagnosis Pain and tingling in the hand is typically present in CTS and absent from MMA; loss of function presents differently; with careful electrophysiological study and neurological exams the two are distinguished. In early stages, ALS, SCA, and MMA, presentation may be similar. Both CSA and ALS ultimately have more extensive symptoms.
Jovian system Irregular satellites Jovian_system > Groups > Irregular satellites Its prograde orbit crosses paths with several moons that have retrograde orbits and may in the future collide with them. Retrograde satellites: The Carme group is tightly confined within semi-major axes between 22–24 million km (14–15 million mi), inclinations between 164–166°, and eccentricities between 0.25 and 0.28. It is very homogeneous in color (light red) and is believed to have originated as collisional fragments from a D-type asteroid progenitor, possibly a Jupiter trojan.
Keldysh formalism Summary Keldysh_formalism In non-equilibrium physics, the Keldysh formalism is a general framework for describing the quantum mechanical evolution of a system in a non-equilibrium state or systems subject to time varying external fields (electrical field, magnetic field etc.). Historically, it was foreshadowed by the work of Julian Schwinger and proposed almost simultaneously by Leonid Keldysh and, separately, Leo Kadanoff and Gordon Baym. It was further developed by later contributors such as O. V. Konstantinov and V. I. Perel.Extensions to driven-dissipative open quantum systems is given not only for bosonic systems, but also for fermionic systems.The Keldysh formalism provides a systematic way to study non-equilibrium systems, usually based on the two-point functions corresponding to excitations in the system. The main mathematical object in the Keldysh formalism is the non-equilibrium Green's function (NEGF), which is a two-point function of particle fields. In this way, it resembles the Matsubara formalism, which is based on equilibrium Green functions in imaginary-time and treats only equilibrium systems.
G2-M DNA damage checkpoint Cyclin B-CDK 1 activity G2-M_DNA_damage_checkpoint > Cyclin B-CDK 1 activity The Novak-Tyson model is a mathematical model used to explain such regulatory loop that predicted the irreversible transition into mitosis driven by hysteresis. Through experiments in Xenopus laevis cell-free egg extracts, such model was confirmed as the basis for entry into mitosis. Once cyclin concentration reaches a certain minimum activation threshold, Cdc2 is rapidly activated.
Simple object S Simple_object > S subcategory A category A is a subcategory of a category B if there is an inclusion functor from A to B. subobject Given an object A in a category, a subobject of A is an equivalence class of monomorphisms to A; two monomorphisms f, g are considered equivalent if f factors through g and g factors through f. subquotient A subquotient is a quotient of a subobject. subterminal object A subterminal object is an object X such that every object has at most one morphism into X. symmetric monoidal category A symmetric monoidal category is a monoidal category (i.e., a category with ⊗) that has maximally symmetric braiding. symmetric sequence A symmetric sequence is a sequence of objects with actions of symmetric groups. It is categorically equivalent to a (combinatorial) species.
Inversional symmetry Chords Inversion_(music) > Chords A chord's inversion describes the relationship of its lowest notes to the other notes in the chord. For instance, a C major triad contains the tones C, E and G; its inversion is determined by which of these tones is the lowest note (or bass note) in the chord. The term inversion often categorically refers to the different possibilities, though it may also be restricted to only those chords where the lowest note is not also the root of the chord. Texts that follow this restriction may use the term position instead, to refer to all of the possibilities as a category.
Non-linear iterative partial least squares Further considerations Principal_Components_Analysis > Further considerations This means that whenever the different variables have different units (like temperature and mass), PCA is a somewhat arbitrary method of analysis. (Different results would be obtained if one used Fahrenheit rather than Celsius for example.) Pearson's original paper was entitled "On Lines and Planes of Closest Fit to Systems of Points in Space" – "in space" implies physical Euclidean space where such concerns do not arise.
History of logarithms Common logarithm History_of_logarithms > Common logarithm As the common log of ten is one, of a hundred is two, and a thousand is three, the concept of common logarithms is very close to the decimal-positional number system. The common log is said to have base 10, but base 10,000 is ancient and still common in East Asia. In his book The Sand Reckoner, Archimedes used the myriad as the base of a number system designed to count the grains of sand in the universe. As was noted in 2000: In antiquity Archimedes gave a recipe for reducing multiplication to addition by making use of geometric progression of numbers and relating them to an arithmetic progression.In 1616 Henry Briggs visited John Napier at Edinburgh in order to discuss the suggested change to Napier's logarithms.
Abelian Higgs model Non-Abelian Higgs mechanism Higgs_mechanism > Examples > Non-Abelian Higgs mechanism Depending on the representation of the scalar field, not every gauge field acquires a mass. A simple example is in the renormalizable version of an early electroweak model due to Julian Schwinger.
Viral oncogene protein Inactivation of p53 Viral_oncogene_protein > DNA oncoviruses > Inactivation of p53 Viruses employ various methods of inactivating p53. The adenovirus E1B protein (55K) prevents p53 from regulating genes by binding to the site on p53 which binds to the genome. In SV40, the large T antigen (LT) is an analogue; LT also binds to several other cellular proteins, such as p107 and p130, on the same residues. LT binds to p53's binding domain on the DNA (rather than on the protein), again preventing p53 from appropriately regulating genes. HPV instead degrades p53: the HPV protein E6 binds to a cellular protein called the E6-associated protein (E6-AP, also known as UBE3A), forming a complex which causes the rapid and specific ubiquitination of p53.
Blossom algorithm Augmenting paths Blossom_algorithm > Augmenting paths By Berge's lemma, matching M is maximum if and only if there is no M-augmenting path in G. Hence, either a matching is maximum, or it can be augmented. Thus, starting from an initial matching, we can compute a maximum matching by augmenting the current matching with augmenting paths as long as we can find them, and return whenever no augmenting paths are left. We can formalize the algorithm as follows: INPUT: Graph G, initial matching M on G OUTPUT: maximum matching M* on G A1 function find_maximum_matching(G, M): M* A2 P ← find_augmenting_path(G, M) A3 if P is non-empty then A4 return find_maximum_matching(G, augment M along P) A5 else A6 return M A7 end if A8 end function We still have to describe how augmenting paths can be found efficiently. The subroutine to find them uses blossoms and contractions.
Human consciousness Models Phenomenal_consciousness > Scientific study > Models Damage to these cortical regions can lead to deficits in consciousness such as hemispatial neglect. In the attention schema theory, the value of explaining the feature of awareness and attributing it to a person is to gain a useful predictive model of that person's attentional processing. Attention is a style of information processing in which a brain focuses its resources on a limited set of interrelated signals.
Upwelling current Effect on climate Upwelling > Effect on climate Coastal upwelling has a major influence over the affected region's local climate. This effect is magnified if the ocean current is already cool. As the cold, nutrient-rich water moves upwards and the sea surface temperature gets cooler, the air immediately above it also cools down and is likely to condensate, forming sea fog and stratus clouds. This also inhibits the formation of higher altitude clouds, showers and thunderstorms and results in rainfall over the ocean leaving the land dry.
Controller Area Network Physical organization Controller-area_network > Architecture > Physical organization CAN is a multi-master serial bus standard for connecting electronic control units (ECUs) also known as nodes (automotive electronics is a major application domain). Two or more nodes are required on the CAN network to communicate. A node may interface to devices from simple digital logic e.g. PLD, via FPGA up to an embedded computer running extensive software. Such a computer may also be a gateway allowing a general-purpose computer (like a laptop) to communicate over a USB or Ethernet port to the devices on a CAN network.
Barraquer–Simons syndrome Prognosis Barraquer–Simons_syndrome > Prognosis About 40-50% of patients develop end-stage renal disease over the course of 10 years. This condition is responsible for most recurrent hospital admissions in patients with acquired partial lipodystrophy. Rapid progression of renal disease in a pregnant patient was reported.
Validated numerics Accidents caused by numerical errors Validated_numerics > Importance > Accidents caused by numerical errors The following examples are known as accidents caused by numerical errors: Failure of intercepting missiles in the Gulf War (1991) Failure of the Ariane 5 rocket (1996) Mistakes in election result totalization
Hemicrania continua Summary Hemicrania_continua Hemicrania continua (HC) is a persistent unilateral headache that responds to indomethacin. It is usually unremitting, but rare cases of remission have been documented. Hemicrania continua is considered a primary headache disorder, meaning that another condition does not cause it.
Neural circuit Summary Neural_circuit A neural circuit (also known as a biological neural network BNNs) is a population of neurons interconnected by synapses to carry out a specific function when activated. Multiple neural circuits interconnect with one another to form large scale brain networks.Neural circuits have inspired the design of artificial neural networks, though there are significant differences.
Granular layer (cerebellum) Structure Granule_cell_layer > Structure At the level of gross anatomy, the cerebellum consists of a tightly folded layer of cortex, with white matter underneath and a fluid-filled ventricle at the base. Four deep cerebellar nuclei are embedded in the white matter. Each part of the cortex consists of the same small set of neuronal elements, laid out in a highly stereotyped geometry. At an intermediate level, the cerebellum and its auxiliary structures can be separated into several hundred or thousand independently functioning modules called "microzones" or "microcompartments".
Telomeric repeat-containing RNAs Immunodeficiency, Centromeric Region Instability, Facial Anomalies (ICF Syndrome) Telomeric_Repeat-Containing_RNA_(TERRA) > Proposed Role in Human Disease > Immunodeficiency, Centromeric Region Instability, Facial Anomalies (ICF Syndrome) Further evidence also shows a decrease in trimethylated histone H3K9 at the telomeres and loss of binding of the Shelerin-component TRF2 at the subtelomeres. As a result, the increased TERRA expression further contributes to abnormal shorting of the telomere, leading to the spontaneous genomic instability and systemic immunodeficiency. At the minimum, there appears to be a causal link between DNA methylation, TERRA regulation, and telomere length - although the relationship is currently not well understood.
Model transformation Unidirectional versus bidirectional Model_transformation > Classification of model transformations > Unidirectional versus bidirectional A unidirectional model transformation has only one mode of execution: that is, it always takes the same type of input and produces the same type of output. Unidirectional model transformations are useful in compilation-like situations, where any output model is read-only. The relevant notion of consistency is then very simple: the input model is consistent with the model that the transformation would produce as output, only. For a bidirectional model transformation, the same type of model can sometimes be input and other times be output.

Subsets and Splits

No community queries yet

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