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Space Time Continuum Mutual time dilation Lorentz_interval > Spacetime in special relativity > Mutual time dilation and the twin paradox > Mutual time dilation This shows that the time interval OD is longer than OA, showing that the "moving" clock runs slower. : 124 In the lower picture the frame S is moving with velocity −v in the frame S′ at rest. The worldline of clock W is the ct-axis (slanted to the left), the worldline of W′1 is the vertical ct′-axis, and the worldline of W′2 is the vertical through event C, with ct′-coordinate D. The invariant hyperbola through event C scales the time interval OC to OA, which is shorter than OD; also, B is constructed (similar to D in the upper pictures) as simultaneous to A in S, at x = 0.
Stewardship cessation Satellites Stewardship_cessation > Examples > Satellites Another example is when geostationary communications satellites reach the end of their useful lives. Stewardship cessation will occur hopefully in a planned manner, where the operator will move the satellite to a somewhat higher orbit to minimise the risk that the satellite will be a collision hazard to other satellites in the geostationary arc (graveyard burn). Unplanned stewardship cessation will occur if telecommand access to the satellite's systems is cut off due to a failure, for instance in the telecommand receivers.
Humphrey cycle Summary Humphrey_cycle Static pressure and density of the gas decrease. Constant-pressure heat rejection. In this step, heat is removed from the working fluid while the fluid remains at constant pressure. In open-cycle engines this process usually represents expulsion of the gas from the engine, where it quickly equalizes to ambient pressure and slowly loses heat to the atmosphere, which is considered to be an infinitely large reservoir for heat storage, with constant pressure and temperature. == References ==
Holonomic constraint Classification of physical systems Holonomic_constraint > Holonomic system > Classification of physical systems In order to study classical physics rigorously and methodically, we need to classify systems. Based on previous discussion, we can classify physical systems into holonomic systems and non-holonomic systems. One of the conditions for the applicability of many theorems and equations is that the system must be a holonomic system. For example, if a physical system is a holonomic system and a monogenic system, then Hamilton's principle is the necessary and sufficient condition for the correctness of Lagrange's equation.
Isotope Radioactive isotopes Isotope > History > Radioactive isotopes Soddy proposed that several types of atoms (differing in radioactive properties) could occupy the same place in the table. For example, the alpha-decay of uranium-235 forms thorium-231, whereas the beta decay of actinium-230 forms thorium-230.
Fracture in polymers Built-up heat from hysteresis Fracture_in_polymers > Fatigue Failure > Built-up heat from hysteresis Polymers are viscoelastic by nature, and exhibit mechanical hysteresis even at moderate strains due to continuous elongation and contraction. Some of this inelastic deformation energy is dissipated as heat within the polymer, and consequently the materials temperature will rise as a function of frequency, testing temperature, the stress cycle and the type of polymer. As the temperature within the polymer rises, the stiffness and yield strength will fall, and thermal failure becomes a possibility as deformation levels become excessive.
Electrocution Medical aspects Electrocution > Medical aspects Fish & Geddes state: "Contact with 20 mA of current can be fatal".The health hazard of an electric current flowing through the body depends on the amount of current and the length of time for which it flows, not merely on the voltage. However, a high voltage is required to produce a high current through the body. This is due to the relatively high resistance of skin when dry, requiring a high voltage to pass through. The severity of a shock also depends on whether the path of the current includes a vital organ.
Human memory Cognitive neuroscience Human_memory > Cognitive neuroscience Working memory. Recent functional imaging studies detected working memory signals in both medial temporal lobe (MTL), a brain area strongly associated with long-term memory, and prefrontal cortex (Ranganath et al. 2005), suggesting a strong relationship between working memory and long-term memory. However, the substantially more working memory signals seen in the prefrontal lobe suggest that this area plays a more important role in working memory than MTL (Suzuki 2007).
Base of lung Obstructive lung diseases Oblique_fissure > Clinical significance > Obstructive lung diseases A common cause of chronic bronchitis, and emphysema, is smoking; and common causes of bronchiectasis include severe infections and cystic fibrosis. The definitive cause of asthma is not yet known, but it has been linked to other atopic diseases.The breakdown of alveolar tissue, often as a result of tobacco-smoking leads to emphysema, which can become severe enough to develop into COPD. Elastase breaks down the elastin in the lung's connective tissue that can also result in emphysema.
Optimal design of experiments Historical Optimal_design_of_experiments > Further reading > Historical Operations Research. 15 (4): 643–648. doi:10.1287/opre.15.4.643.
Synthesis phase Nucleosome replication Synthesis_phase > Nucleosome replication Free histones produced by the cell during S-phase are rapidly incorporated into new nucleosomes. This process is closely tied to the replication fork, occurring immediately in “front” and “behind” the replication complex. Translocation of MCM helicase along the leading strand disrupts parental nucleosome octamers, resulting in the release of H3-H4 and H2A-H2B subunits. Reassembly of nucleosomes behind the replication fork is mediated by chromatin assembly factors (CAFs) that are loosely associated with replication proteins.
Diatomic carbon Electromagnetic properties Diatomic_carbon > Properties > Electromagnetic properties Molecular orbital theory shows that there are two sets of paired electrons in a degenerate pi bonding set of orbitals. This gives a bond order of 2, meaning that there should exist a double bond between the two carbon atoms in a C2 molecule. One analysis suggested instead that a quadruple bond exists, an interpretation that was disputed.
Matrix decoder Notation Matrix_decoder > Notation The notation for matrix encoding consists of the number of original discrete audio channels separated by a colon from the number of encoded and decoded channels. For example, four channels encoded into two discrete channels and decoded back to four-channels would be notated: 4:2:4 Some methods derive new channels from the existing ones, with no special encoding of the audio source. For example, five discrete channels decoded to six channels would be notated: 5:5:6 Such derived channel "decoders" may take advantage of the Haas effect, as well as audio cues inherent in the source channels. Many matrix encoding methods have been developed:
GNU Units Other implementations GNU_Units > History > Other implementations UDUNITS is a similar utility program, except that it has an additional programming library interface and date conversion abilities. UDUNITS is considered the de facto program and library for variable unit conversion for netCDF files.
Metaplectic representation Fourier transform Metaplectic_representation > Fourier transform The Fourier transform is defined on S {\displaystyle {\mathcal {S}}} by f ^ ( ξ ) = 1 2 π ∫ − ∞ ∞ f ( x ) e − i x ξ d x . {\displaystyle {\widehat {f}}(\xi )={1 \over {\sqrt {2\pi }}}\int _{-\infty }^{\infty }f(x)e^{-ix\xi }\,dx.} It defines a continuous map of S {\displaystyle {\mathcal {S}}} into itself for its natural topology.
Octagon Area Regular_octagon > Properties > Area Given the length of a side a, the span S is S = a 2 + a + a 2 = ( 1 + 2 ) a ≈ 2.414 a . {\displaystyle S={\frac {a}{\sqrt {2}}}+a+{\frac {a}{\sqrt {2}}}=(1+{\sqrt {2}})a\approx 2.414a.} The span, then, is equal to the silver ratio times the side, a. The area is then as above: A = ( ( 1 + 2 ) a ) 2 − a 2 = 2 ( 1 + 2 ) a 2 ≈ 4.828 a 2 .
Airplane wing Airplane/aeroplane Fixed_wing_aircraft > Classes of fixed-wing aircraft > Airplane/aeroplane An airplane (also known as an aeroplane or simply a plane) is a powered fixed-wing aircraft that is propelled forward by thrust from a jet engine or propeller. Planes come in a variety of sizes, shapes, and wing configurations. The broad spectrum of uses for planes includes recreation, transportation of goods and people, military, and research.
Glass batch calculation Example calculation Glass_batch > Example calculation An example batch calculation may be demonstrated here. The desired glass composition in wt% is: 67 SiO2, 12 Na2O, 10 CaO, 5 Al2O3, 1 K2O, 2 MgO, 3 B2O3, and as raw materials are used sand, trona, lime, albite, orthoclase, dolomite, and borax. The formulas and molar masses of the glass and batch components are listed in the following table: The batching matrix B indicates the relation of the molarity in the batch (columns) and in the glass (rows). For example, the batch component SiO2 adds 1 mol SiO2 to the glass, therefore, the intersection of the first column and row shows "1".
Near ir spectroscopy History Near_ir_spectroscopy > History The discovery of near-infrared energy is ascribed to William Herschel in the 19th century, but the first industrial application began in the 1950s. In the first applications, NIRS was used only as an add-on unit to other optical devices that used other wavelengths such as ultraviolet (UV), visible (Vis), or mid-infrared (MIR) spectrometers. In the 1980s, a single-unit, stand-alone NIRS system was made available.
Subject-matter expert Turing test Summary Subject-matter_expert_Turing_test A subject matter expert Turing test is a variation of the Turing test where a computer system attempts to replicate an expert in a given field such as chemistry or marketing. It is also known, as a Feigenbaum test and was proposed by Edward Feigenbaum in a 2003 paper.The concept is also described by Ray Kurzweil in his 2005 book The Singularity is Near. Kurzweil argues that machines who pass this test are an inevitable consequence of Moore's Law.
Cache algorithm Least-frequently used (LFU) Cache_algorithm > Policies > Simple frequency-based policies > Least-frequently used (LFU) Counts how often an item is needed. Those that are used least often are discarded first. This works very similar to LRU except that instead of storing the value of how recently a block was accessed, we store the value of how many times it was accessed. So of course while running an access sequence we will replace a block which was used fewest times from our cache. E.g., if A was used (accessed) 5 times and B was used 3 times and others C and D were used 10 times each, we will replace B.
Gravitation (book) Reviews Gravitation_(book) > Reviews MTW has a very extensive bibliography. Many texts on general relativity refer to it in their bibliographies or footnotes.
Bullet list Summary Bulleted_list (period), and even o (lowercase Latin letter O), are conventionally used in ASCII-only text or other environments where bullet characters are not available. Historically, the index symbol ☞ (representing a hand with a pointing index finger) was popular for similar uses. Lists made with bullets are called bulleted lists. The HTML element name for a bulleted list is "unordered list", because the list items are not arranged in numerical order (as they would be in a numbered list).
The speed of light in vacuum In a medium Velocity_of_light > Propagation of light > In a medium As an extreme example of light "slowing" in matter, two independent teams of physicists claimed to bring light to a "complete standstill" by passing it through a Bose–Einstein condensate of the element rubidium. However, the popular description of light being "stopped" in these experiments refers only to light being stored in the excited states of atoms, then re-emitted at an arbitrarily later time, as stimulated by a second laser pulse. During the time it had "stopped", it had ceased to be light.
Interaction vertex On a lattice Feynman_diagrams > Path integral formulation > On a lattice The lattice means that fluctuations at large k are not allowed to contribute right away, they only start to contribute in the limit a → 0. Sometimes, instead of a lattice, the field modes are just cut off at high values of k instead. It is also convenient from time to time to consider the space-time volume to be finite, so that the k modes are also a lattice.
Neutral mutation Synonymous mutation of bases Neutral_mutation > Types > Synonymous mutation of bases When an incorrect nucleotide is inserted during replication or transcription of a coding region, it can affect the eventual translation of the sequence into amino acids. Since multiple codons are used for the same amino acids, a change in a single base may still lead to translation of the same amino acid. This phenomenon is referred to as degeneracy and allows for a variety of codon combinations leading to the same amino acid being produced. For example, the codes TCT, TCC, TCA, TCG, AGT, and AGC all code for the amino acid serine.
H-TCP Name H-TCP > Name The algorithm was initially introduced as H-TCP, without mention of what the 'H' stands for. However, it is often called "Hamilton TCP", for the Hamilton Institute where it was created.
Web performance Optimization techniques Web_performance_optimization > Optimization techniques Code minification distinguishes discrepancies between codes written by web developers and how network elements interpret code. Minification removes comments and extra spaces as well as crunch variable names in order to minimize code, decreasing files sizes by as much as 60%. In addition to caching and compression, lossy compression techniques (similar to those used with audio files) remove non-essential header information and lower original image quality on many high resolution images.
Image segmentation Variational methods Image_segmentation > Variational methods The goal of variational methods is to find a segmentation which is optimal with respect to a specific energy functional. The functionals consist of a data fitting term and a regularizing terms. A classical representative is the Potts model defined for an image f {\displaystyle f} by argmin u ⁡ γ ‖ ∇ u ‖ 0 + ∫ ( u − f ) 2 d x . {\displaystyle \operatorname {argmin} _{u}\gamma \|\nabla u\|_{0}+\int (u-f)^{2}\,dx.}
Old Law Tenement Design Old_Law_Tenement > Design Tenants usually placed a table and chairs at the angled window at the end of the narrow airshaft. Most people constructed a shelf at the kitchen window that hung out into the airshaft. During winter, food could be stored there and refrigerated without the expense of buying ice. Two toilets, cramped water closets were located on the landing in the hallway for common use.
Java version history Future features Java_version_history > Future features Project Valhalla: Value classes, whose objects lack identity, but can in certain cases get an improved memory layout (with less indirection), or have their allocation optimized away entirely. Project Panama: Improved interoperability with native code, to enable Java source code to call functions and use data types from other languages, in a way that is easier and has better performance than today. Vector API (a portable and relatively low-level abstraction layer for SIMD programming) is also developed under Project Panama umbrella. Project Lilliput: Reduce the size of Java object headers. First down to 64 bits, and then down to 32 bits.
Spherical law of cosines Summary Spherical_law_of_cosines As a special case, for C = π/2, then cos C = 0, and one obtains the spherical analogue of the Pythagorean theorem: If the law of cosines is used to solve for c, the necessity of inverting the cosine magnifies rounding errors when c is small. In this case, the alternative formulation of the law of haversines is preferable.A variation on the law of cosines, the second spherical law of cosines, (also called the cosine rule for angles) states: where A and B are the angles of the corners opposite to sides a and b, respectively. It can be obtained from consideration of a spherical triangle dual to the given one.
Biofluid dynamics Summary Biofluid_dynamics Biological fluid Dynamics (or Biofluid Dynamics) involves the study of the motion of biological fluids (e.g. blood flow in arteries, animal flight, fish swimming, etc.). It can be either circulatory system or respiratory systems. Understanding the circulatory system is one of the major areas of research.
Stochastic game Summary Stochastic_game The game then moves to a new random state whose distribution depends on the previous state and the actions chosen by the players. The procedure is repeated at the new state and play continues for a finite or infinite number of stages. The total payoff to a player is often taken to be the discounted sum of the stage payoffs or the limit inferior of the averages of the stage payoffs. Stochastic games generalize Markov decision processes to multiple interacting decision makers, as well as strategic-form games to dynamic situations in which the environment changes in response to the players’ choices.
Open Transport Network Summary Open_Transport_Network Open Transport Network (OTN) is a flexible private communication network based on fiber optic technology, manufactured by OTN Systems. It is a networking technology used in vast, private networks with a great diversity of communication requirements, such as subway systems, pipelines, the mining industry, tunnels and the like (ref). It permits all kinds of applications such as video images, different forms of speech and data traffic, information for process management and the like to be sent flawlessly and transparent over a practically unlimited distance. The system is a mix of Transmission and Access NE, communicating over an optical fiber. The communication protocols include serial protocols (e.g. RS232) as well as telephony (POTS/ISDN), audio, Ethernet, video and video-over-IP (via M-JPEG, MPEG2/4, H.264 or DVB) (ref). Open Transport Network is a brand name and not to be mistaken with Optical Transport Network.
History of tuberculosis Seventeenth and eighteenth centuries History_of_tuberculosis > Seventeenth and eighteenth centuries In his Systematik de speziellen Pathologie und Therapie, J. L. Schönlein, Professor of Medicine in Zurich, proposed that the word "tuberculosis" be used to describe the condition of tubercles.The incidence of tuberculosis grew progressively during the Middle Ages and Renaissance, displacing leprosy, peaking between the 18th and 19th century as field workers moved to the cities looking for work. When he released his study in 1808, William Woolcombe was astonished at the prevalence of tuberculosis in 18th-century England. Of the 1,571 deaths in the English city of Bristol between 1790 and 1796, 683 were due to tuberculosis.
Microevolution Mutation Microevolution > Four processes > Mutation Mutations can affect the phenotype of an organism, especially if they occur within the protein coding sequence of a gene. Error rates are usually very low—1 error in every 10–100 million bases—due to the proofreading ability of DNA polymerases. (Without proofreading error rates are a thousandfold higher; because many viruses rely on DNA and RNA polymerases that lack proofreading ability, they experience higher mutation rates.)
Diffraction topography Literature Diffraction_topography > Literature doi:10.1107/s0909049500002995. ISSN 0909-0495. PMID 16609195.
Alcoholic hepatitis Signs and symptoms Alcoholic_hepatitis > Signs and symptoms Alcoholic hepatitis is characterized by a number of symptoms, which may include feeling unwell, enlargement of the liver, development of fluid in the abdomen (ascites), and modest elevation of liver enzyme levels (as determined by liver function tests). May also present with Hepatic encephalopathy (brain dysfunction due to liver failure) causing symptoms such as confusion, decreased levels of consciousness, or asterixis, (a characteristic flapping movement when the wrist is extended indicative of hepatic encephalopathy). Severe cases are characterized by profound jaundice, obtundation (ranging from drowsiness to unconsciousness), and progressive critical illness; the mortality rate is 50% within 30 days of onset despite best care.Alcoholic hepatitis is distinct from cirrhosis caused by long-term alcohol consumption. Alcoholic hepatitis can occur in patients with chronic alcoholic liver disease and alcoholic cirrhosis.
Antileukotriene agent Approaches Leukotriene_antagonist > Approaches There are two main approaches to block the actions of leukotrienes.
Hydraulic model Equation examples Hydraulic_analogy > Equation examples If the differential equations are equivalent in form, the dynamics of the systems they describe will be related. The example hydraulic equations approximately describe the relationship between a constant, laminar flow in a cylindrical pipe and the difference in pressure at each end, as long as the flow is not analyzed near the ends of the pipe. The example electric equations approximately describe the relationship between a current in a straight wire and the difference in electric potential (voltage).
Matrix completion Gradient descent Matrix_completion > Algorithms for Low-Rank Matrix Completion > Gradient descent They then propose the following algorithm: Trim M E {\displaystyle M^{E}} by removing all observations from columns with degree larger than 2 | E | n {\displaystyle {\frac {2|E|}{n}}} by setting the entries in the columns to 0. Similarly remove all observations from rows with degree larger than 2 | E | n {\displaystyle {\frac {2|E|}{n}}} . Project M E {\displaystyle M^{E}} onto its first r {\displaystyle r} principal components.
Medical Image Computing Classification Medical_Image_Computing > Statistical analysis > Classification A remedy to this problem is to reduce the number of features in an informative sense (see dimensionality reduction). Several unsupervised and semi-/supervised, approaches have been proposed to address this issue.
Brouwer fixed-point Boundedness Brouwer_Fixed_Point_Theorem > Importance of the pre-conditions > Boundedness Consider the function f ( x ) = x + 1 , {\displaystyle f(x)=x+1,} which is a continuous function from R {\displaystyle \mathbb {R} } to itself. As it shifts every point to the right, it cannot have a fixed point. The space R {\displaystyle \mathbb {R} } is convex and closed, but not bounded.
Word combinatorics Definition Combinatorics_on_words > Definition In mathematics various structures are used to encode data. A common structure used in combinatorics is the tree structure. A tree structure is a graph where the vertices are connected by one line, called a path or edge.
Satellite orbit Orbital decay Planetary_motion > Perturbations > Orbital decay If an orbit is about a planetary body with a significant atmosphere, its orbit can decay because of drag. Particularly at each periapsis, the object experiences atmospheric drag, losing energy. Each time, the orbit grows less eccentric (more circular) because the object loses kinetic energy precisely when that energy is at its maximum. This is similar to the effect of slowing a pendulum at its lowest point; the highest point of the pendulum's swing becomes lower.
Cell transfer therapy Dendritic cell therapy Immune_checkpoint_inhibitor > Cellular immunotherapy > Dendritic cell therapy Dendritic cell therapy provokes anti-tumor responses by causing dendritic cells to present tumor antigens to lymphocytes, which activates them, priming them to kill other cells that present the antigen. Dendritic cells are antigen-presenting cells (APCs) in the mammalian immune system. In cancer treatment they aid cancer antigen targeting. The only approved cellular cancer therapy based on dendritic cells is sipuleucel-T.
Feynman graph Loop order Feynman_diagram > Path integral formulation > Equation of motion > Loop order This diagram has no external lines at all. The reason loop diagrams are called loop diagrams is because the number of k-integrals that are left undetermined by momentum conservation is equal to the number of independent closed loops in the diagram, where independent loops are counted as in homology theory. The homology is real-valued (actually Rd valued), the value associated with each line is the momentum.
Transformational syntax Overview Transformational_syntax > Overview According to the Chomskyan tradition, language acquisition is easy for children because they are born with a universal grammar in their minds. The tradition also distinguishes between linguistic competence, what a person knows of a language, and linguistic performance, how a person uses it. Finally, grammars and metagrammars are ranked by three levels of adequacy: observational, descriptive, and explanatory.
Superspreading event COVID-19 pandemic: 2020–present Superspreading_event > Superspreaders during outbreaks or pandemics > COVID-19 pandemic: 2020–present One person who attended the party had recently returned from South Africa, the epicenter of the SARS-CoV-2 Omicron variant outbreak and a country where the company has a solar panel project. It was later found that the attendee from South Africa had been infected with the Omicron variant. More than half of the party's attendees have since tested positive for COVID-19 and of those attendees, at least 13 of them were confirmed to have the variant.On 3 April 2022, the Gridiron Dinner in Washington D.C. led to at least 67 people testing positive for COVID-19, including three members of the Cabinet of Joe Biden: Merrick Garland, Gina Raimondo, and Tom Vilsack.
Heterolysis (chemistry) Solvation effects Heterolytic_fission > Solvation effects The rate of reaction for many reactions involving unimolecular heterolysis depends heavily on rate of ionization of the covalent bond. The limiting reaction step is generally the formation of ion pairs. One group in Ukraine did an in-depth study on the role of nucleophilic solvation and its effect on the mechanism of bond heterolysis. They found that the rate of heterolysis depends strongly on the nature of the solvent.
Complex Network Definition Complex_Network > Definition Both are characterized by specific structural features—power-law degree distributions for the former and short path lengths and high clustering for the latter. However, as the study of complex networks has continued to grow in importance and popularity, many other aspects of network structures have attracted attention as well. The field continues to develop at a brisk pace, and has brought together researchers from many areas including mathematics, physics, electric power systems, biology, climate, computer science, sociology, epidemiology, and others. Ideas and tools from network science and engineering have been applied to the analysis of metabolic and genetic regulatory networks; the study of ecosystem stability and robustness; clinical science; the modeling and design of scalable communication networks such as the generation and visualization of complex wireless networks; and a broad range of other practical issues. Network science is the topic of many conferences in a variety of different fields, and has been the subject of numerous books both for the lay person and for the expert.
Postural Orthostatic Tachycardia Syndrome Diagnosis Postural_Orthostatic_Tachycardia_Syndrome > Diagnosis POTS is most commonly diagnosed by a cardiologist (41%), cardiac electrophysiologist (15%), or neurologist (19%). The average number of physicians seen before receiving diagnosis is seven, and the average delay before diagnosis is 4.7 years.
Fission products (by element) Lanthanides (lanthanum-139, cerium-140 to 144, neodymium-142 to 146, 148, 150, promethium-147, and samarium-149, 151, 152, 154) Fission_products_(by_element) > Lanthanides (lanthanum-139, cerium-140 to 144, neodymium-142 to 146, 148, 150, promethium-147, and samarium-149, 151, 152, 154) A great deal of the lighter lanthanides (lanthanum, cerium, neodymium, and samarium) are formed as fission products. In Africa, at Oklo where the natural nuclear fission reactor operated over a billion years ago, the isotopic mixture of neodymium is not the same as 'normal' neodymium, it has an isotope pattern very similar to the neodymium formed by fission. In the aftermath of criticality accidents, the level of 140La is often used to determine the fission yield (in terms of the number of nuclei which underwent fission). Samarium-149 is the second most important neutron poison in nuclear reactor physics.
Infinite list Summary Lazy_allocation This allows for rapid prototyping.Lazy evaluation is often combined with memoization, as described in Jon Bentley's Writing Efficient Programs. After a function's value is computed for that parameter or set of parameters, the result is stored in a lookup table that is indexed by the values of those parameters; the next time the function is called, the table is consulted to determine whether the result for that combination of parameter values is already available. If so, the stored result is simply returned.
Electronic feedback loop Positive and negative feedback Feedback_loop > Types > Positive and negative feedback Black had trouble convincing others of the utility of his invention in part because confusion existed over basic matters of definition. : 121 Even before these terms were being used, James Clerk Maxwell had described their concept through several kinds of "component motions" associated with the centrifugal governors used in steam engines. He distinguished those that lead to a continued increase in a disturbance or the amplitude of a wave or oscillation, from those that lead to a decrease of the same quality.
Qualitative chemical analysis Hybrid techniques Qualitative_chemical_analysis > Instrumental methods > Hybrid techniques Most often the other technique is some form of chromatography. Hyphenated techniques are widely used in chemistry and biochemistry. A slash is sometimes used instead of hyphen, especially if the name of one of the methods contains a hyphen itself.
EM field Time-varying EM fields in Maxwell’s equations EM_field > Applications > Time-varying EM fields in Maxwell’s equations Otherwise, they appear parasitically around conductors which absorb EMR, and around antennas which have the purpose of generating EMR at greater distances. Changing magnetic dipole fields (i.e., magnetic near-fields) are used commercially for many types of magnetic induction devices.
Inorganic anhydride Chlorine oxides Inorganic_acid_anhydride > Further examples > Chlorine oxides Chlorine(I) oxide reacts with water to form hypochlorous acid, a very weak acid: Cl 2 O + H 2 O ↽ − − ⇀ 2 HOCl {\displaystyle {\ce {Cl2O + H2O <=> 2 HOCl}}} Chlorine(VII) oxide reacts with water to form perchloric acid, a strong acid: Cl2O7 + H2O → 2 HClO4
Product topology Axiom of choice Topological_product > Axiom of choice One of many ways to express the axiom of choice is to say that it is equivalent to the statement that the Cartesian product of a collection of non-empty sets is non-empty. The proof that this is equivalent to the statement of the axiom in terms of choice functions is immediate: one needs only to pick an element from each set to find a representative in the product. Conversely, a representative of the product is a set which contains exactly one element from each component. The axiom of choice occurs again in the study of (topological) product spaces; for example, Tychonoff's theorem on compact sets is a more complex and subtle example of a statement that requires the axiom of choice and is equivalent to it in its most general formulation, and shows why the product topology may be considered the more useful topology to put on a Cartesian product.
Poker table Summary Poker_table A poker table or card table is a table specifically designed for playing card games.
Complexity classes Summary Complexity_class The study of the relationships between complexity classes is a major area of research in theoretical computer science. There are often general hierarchies of complexity classes; for example, it is known that a number of fundamental time and space complexity classes relate to each other in the following way: NL⊆P⊆NP⊆PSPACE⊆EXPTIME⊆EXPSPACE (where ⊆ denotes the subset relation). However, many relationships are not yet known; for example, one of the most famous open problems in computer science concerns whether P equals NP. The relationships between classes often answer questions about the fundamental nature of computation. The P versus NP problem, for instance, is directly related to questions of whether nondeterminism adds any computational power to computers and whether problems having solutions that can be quickly checked for correctness can also be quickly solved.
DNA code construction Definitions DNA_code_construction > Definitions Most of the focus on DNA coding has been on constructing large sets of DNA codewords with prescribed minimum distance properties. For this purpose let us lay down the required groundwork to proceed further. Let q = q 1 q 2 … q n {\displaystyle {\mathit {q}}={\mathit {q}}_{1}{\mathit {q}}_{2}\dots {\mathit {q}}_{n}} be a word of length n {\displaystyle {\mathit {n}}} over the alphabet Q {\displaystyle {\mathcal {Q}}} .
Dense graph Summary Sparse_graph In mathematics, a dense graph is a graph in which the number of edges is close to the maximal number of edges (where every pair of vertices is connected by one edge). The opposite, a graph with only a few edges, is a sparse graph. The distinction of what constitutes a dense or sparse graph is ill-defined, and is often represented by 'roughly equal to' statements. Due to this, the way that density is defined often depends on the context of the problem.
Intracellular signaling peptides and proteins Ligands Signal_transduction_pathway > Stimuli > Ligands The majority of signal transduction pathways involve the binding of signaling molecules, known as ligands, to receptors that trigger events inside the cell. The binding of a signaling molecule with a receptor causes a change in the conformation of the receptor, known as receptor activation. Most ligands are soluble molecules from the extracellular medium which bind to cell surface receptors.
Drive-by download Detection and prevention Drive-by_download > Detection and prevention Detection of drive-by download attacks is an active area of research. Some methods of detection involve anomaly detection, which tracks for state changes on a user's computer system while the user visits a webpage. This involves monitoring the user's computer system for anomalous changes when a web page is rendered. Other methods of detection include detecting when malicious code (shellcode) is written to memory by an attacker's exploit.
Slater determinants Example: Matrix elements in a many electron problem Slater_determinant > Example: Matrix elements in a many electron problem ψ N | G 2 | det { ψ 1 . . .
Water trough Summary Water_trough A water trough (British terminology), or track pan (American terminology), is a device to enable a steam locomotive to replenish its water supply while in motion. It consists of a long trough filled with water, lying between the rails. When a steam locomotive passes over the trough, a water scoop can be lowered, and the speed of forward motion forces water into the scoop, up the scoop pipe and into the tanks or locomotive tender.
Ocean observatory Ocean subsurface Ocean_Observations > Ocean climate variables > Ocean subsurface Backscatter Carbon Dioxide Chlorophyll Conductivity Density Iron Irradiance Nutrients Nitrate Methane Ocean current Single Point Water Column Ocean tracers Oxygen Phytoplankton Salinity Sigma-T Sound Velocity Temperature Turbidity
Cloud Security Confidentiality Cloud_Security > Data security > Confidentiality Data confidentiality is the property in that data contents are not made available or disclosed to illegal users. Outsourced data is stored in a cloud and out of the owners' direct control. Only authorized users can access the sensitive data while others, including CSPs, should not gain any information about the data.
Amorphous computing Algorithms, tools, and patterns Amorphous_computing > Algorithms, tools, and patterns Message strength will follow the inverse square law as described by Fick's law of diffusion. Examples of such communication are common in biological and chemical systems. "Link diffusive communication".
Human-factor engineering Physical ergonomics Physical_ergonomics > Domains of specialization > Physical ergonomics Physical ergonomics is concerned with human anatomy, and some of the anthropometric, physiological, and biomechanical characteristics as they relate to physical activity. Physical ergonomic principles have been widely used in the design of both consumer and industrial products for optimizing performance and to preventing / treating work-related disorders by reducing the mechanisms behind mechanically induced acute and chronic musculoskeletal injuries / disorders. Risk factors such as localized mechanical pressures, force and posture in a sedentary office environment lead to injuries attributed to an occupational environment. Physical ergonomics is important to those diagnosed with physiological ailments or disorders such as arthritis (both chronic and temporary) or carpal tunnel syndrome.
Factorial Divisibility and digits Factorial > Properties > Divisibility and digits ⋅ 3 ! ⋅ 2 ! {\displaystyle 9!=7!\cdot 3!\cdot 3!\cdot 2!}
Trophoblastic neoplasm Prognosis Trophoblastic_neoplasm > Prognosis FIGO modified Prognostic Scoring System. The system evaluates the patients to those with GTN as low-risk and high-risk based on several risk factors such as age, pregnancy or interval of pregnancies, size or metastases of tumor and prior chemotherapy. Each risk factors are rated at levels 0-4 scores. The numbers are then added up, and the overall score determines a woman's risk level.
Nonalcoholic steatohepatitis Prognosis Nonalcoholic_fatty_liver_disease > Prognosis Although MAFLD can cause cirrhosis and liver failure and liver cancer, most deaths among people with NAFLD are attributable to cardiovascular disease. According to a meta-analysis of 34,000 people with MAFLD over seven years, these individuals have a 65% increased risk of developing fatal or nonfatal cardiovascular events when compared to those without MAFLD.MAFLD and NASH increase the risk of liver cancer. Cirrhosis and liver cancer induced by NAFLD were the second cause of liver transplantation in the US in 2017.
Hash algorithm Overview Hash_functions > Overview Map the key values into ones less than or equal to the size of the tableA good hash function satisfies two basic properties: 1) it should be very fast to compute; 2) it should minimize duplication of output values (collisions). Hash functions rely on generating favourable probability distributions for their effectiveness, reducing access time to nearly constant. High table loading factors, pathological key sets and poorly designed hash functions can result in access times approaching linear in the number of items in the table.
Auditory vestibular nerve Summary Vestibulocochlear_nerve The vestibulocochlear nerve or auditory vestibular nerve, also known as the eighth cranial nerve, cranial nerve VIII, or simply CN VIII, is a cranial nerve that transmits sound and equilibrium (balance) information from the inner ear to the brain. Through olivocochlear fibers, it also transmits motor and modulatory information from the superior olivary complex in the brainstem to the cochlea.
W. D. Hamilton Hamilton's rule W._D._Hamilton > Hamilton's rule This became Hamilton's rule: in each behaviour-evoking situation, the individual assesses his neighbour's fitness against his own according to the coefficients of relationship appropriate to the situation. Algebraically, the rule posits that a costly action should be performed if: where C is the cost in fitness to the actor, r the genetic relatedness between the actor and the recipient, and B is the fitness benefit to the recipient. Fitness costs and benefits are measured in fecundity.
American Registry for Internet Numbers Registration services American_Registry_for_Internet_Numbers > Services > Registration services Registration services pertain to the technical coordination and inventory management of Internet number resources. Services include: IPv4 address allocation and assignment IPv6 address allocation and assignment AS number assignment Directory services including: Registration transaction information (WHOIS) Routing information (Internet routing registry) DNS (Reverse)For information on requesting Internet number resources from ARIN, see https://www.arin.net/resources/index.html. This section includes the request templates, specific distribution policies, and guidelines for requesting and managing Internet number resources.
Simple Network Management Protocol Protocol details Simple_Network_Management_Protocol > Protocol details SetRequest A manager-to-agent request to change the value of a variable or list of variables. Variable bindings are specified in the body of the request. Changes to all specified variables are to be made as an atomic operation by the agent.
Cardinal numbers Motivation Cardinal_multiplication > Motivation For finite sets and sequences it is easy to see that these two notions coincide, since for every number describing a position in a sequence we can construct a set that has exactly the right size. For example, 3 describes the position of 'c' in the sequence <'a','b','c','d',...>, and we can construct the set {a,b,c}, which has 3 elements. However, when dealing with infinite sets, it is essential to distinguish between the two, since the two notions are in fact different for infinite sets.
Usability Engineering Summary Usability_Engineering Usability Engineering is a professional discipline that focuses on improving the usability of interactive systems. It draws on theories from computer science and psychology to define problems that occur during the use of such a system. Usability Engineering involves the testing of designs at various stages of the development process, with users or with usability experts. The history of usability engineering in this context dates back to the 1980s.
Metal fabrication Processes Metal_fabrication > Processes Assembling (joining of pieces) is done by welding, binding with adhesives, riveting, threaded fasteners, or further bending in the form of crimped seams. Structural steel and sheet metal are the usual materials for fabrication; welding wire, flux and/or fasteners are used to join the cut pieces.Fabrication comprises or overlaps with various metalworking specialties: Fabrication shops and machine shops have overlapping capabilities, but fabrication shops generally concentrate on metal preparation and assembly (as described above). Machine shops cut metal, but focus primarily on the machining of parts on machine tools.
Horizontal transmission Summary Horizontal_transmission Horizontal transmission is the transmission of organisms between biotic and/or abiotic members of an ecosystem that are not in a parent-progeny relationship. This concept has been generalized to include transmissions of infectious agents, symbionts, and cultural traits between humans.Because the evolutionary fate of the agent is not tied to reproductive success of the host, horizontal transmission tends to evolve virulence. It is therefore a critical concept for evolutionary medicine.
Matter waves Neutral atoms De_Broglie_Hypothesis > Applications of matter waves > Neutral atoms Atom interferometers, similar to optical interferometers, measure the difference in phase between atomic matter waves along different paths. Atom optics mimic many light optic devices, including mirrors, atom focusing zone plates. Scanning helium microscopy uses He atom waves to images solid structures non-destructively. Quantum reflection uses matter wave behavior to explain grazing angle atomic reflection, the basis of some atomic mirrors. Quantum decoherence measurements rely on Rb atom wave interference.
Proprioception Etymology Proprioception > History of study > Etymology Proprioception is from Latin proprius, meaning "one's own", "individual", and capio, capere, to take or grasp. Thus to grasp one's own position in space, including the position of the limbs in relation to each other and the body as a whole.The word kinesthesia or kinæsthesia (kinesthetic sense) refers to movement sense, but has been used inconsistently to refer either to proprioception alone or to the brain's integration of proprioceptive and vestibular inputs. Kinesthesia is a modern medical term composed of elements from Greek; kinein "to set in motion; to move" (from PIE root *keie- "to set in motion") + aisthesis "perception, feeling" (from PIE root *au- "to perceive").
Hypoventilation training Physiological effects Hypoventilation_training > Physiological effects When exercise is being performed, if the exhale-hold technique is properly applied, a decrease in O2 concentrations and an increase in CO2 concentrations occur in the lungs, the blood and the muscles. The combined effect of hypoxia and hypercapnia act as a strong stimulus whose main consequence is to increase lactic acid and hydrogen ions production, and therefore to provoke a strong acidosis in the body. Thus, during exercise with hypoventilation, the blood and muscle acid–base homeostasis is highly disturbed. The studies have also reported an increase in all heart activity when hypoventilation is carried out in terrestrial sports.
U6 spliceosomal RNA Summary U6_spliceosomal_RNA U6 snRNA is the non-coding small nuclear RNA (snRNA) component of U6 snRNP (small nuclear ribonucleoprotein), an RNA-protein complex that combines with other snRNPs, unmodified pre-mRNA, and various other proteins to assemble a spliceosome, a large RNA-protein molecular complex that catalyzes the excision of introns from pre-mRNA. Splicing, or the removal of introns, is a major aspect of post-transcriptional modification and takes place only in the nucleus of eukaryotes. The RNA sequence of U6 is the most highly conserved across species of all five of the snRNAs involved in the spliceosome, suggesting that the function of the U6 snRNA has remained both crucial and unchanged through evolution. It is common in vertebrate genomes to find many copies of the U6 snRNA gene or U6-derived pseudogenes.
Gastric bypass surgery Venous thromboembolism Gastric_bypass_surgery > Complications > Complications of abdominal surgery > Venous thromboembolism Due to insufflation of the abdominal cavity with CO2 for the surgery the venous return is diminished and this will lead to deep vein thrombosis of the lower extremities. There is an increased probability of the formation of clots in the veins of the legs, or sometimes the pelvis, particularly in the morbidly obese patient. A clot that breaks free and floats to the lungs is called a pulmonary embolus, a very dangerous occurrence. Blood thinners are commonly administered before surgery to reduce the probability of this type of complication.
Project Grab Bag Background Project_Grab_Bag > Background The fission of uranium or plutonium therefore produces a spectrum of different pairs of nuclei, generally in a bimodal mass distribution. The fission products will include isotopes of many elements and this includes the inert gases such as xenon and krypton. Some of the radioactive isotopes of these inert elements have half-lives or the order of days, and these isotopes have therefore decayed away and are not found in our solar system.
Population Genetics Mutation Population_geneticist > Four processes > Mutation The occurrence of mutations in individuals is represented by a population-level "force" or "pressure" of mutation, i.e., the force of innumerable events of mutation with a scaled magnitude u applied to shifting frequencies f(A1) to f(A2). For instance, in the classic mutation–selection balance model, the force of mutation pressure pushes the frequency of an allele upward, and selection against its deleterious effects pushes the frequency downward, so that a balance is reached at equilibrium, given (in the simplest case) by f = u/s. This concept of mutation pressure is mostly useful for considering the implications of deleterious mutation, such as the mutation load and its implications for the evolution of the mutation rate.
Uses of trigonometry Statistics, including mathematical psychology Uses_of_trigonometry > Some modern uses > Statistics, including mathematical psychology There is a theoretical reason for this, and it involves Fourier transforms and hence trigonometric functions. That is one of a variety of applications of Fourier transforms to statistics. Trigonometric functions are also applied when statisticians study seasonal periodicities, which are often represented by Fourier series.
Protein degradation Summary Proteolysis Proteolysis in organisms serves many purposes; for example, digestive enzymes break down proteins in food to provide amino acids for the organism, while proteolytic processing of a polypeptide chain after its synthesis may be necessary for the production of an active protein. It is also important in the regulation of some physiological and cellular processes including apoptosis, as well as preventing the accumulation of unwanted or misfolded proteins in cells. Consequently, abnormality in the regulation of proteolysis can cause disease. Proteolysis can also be used as an analytical tool for studying proteins in the laboratory, and it may also be used in industry, for example in food processing and stain removal.
Classical analysis Measure theory Mathematical_Analysis > Main branches > Measure theory Technically, a measure is a function that assigns a non-negative real number or +∞ to (certain) subsets of a set X {\displaystyle X} . It must assign 0 to the empty set and be (countably) additive: the measure of a 'large' subset that can be decomposed into a finite (or countable) number of 'smaller' disjoint subsets, is the sum of the measures of the "smaller" subsets. In general, if one wants to associate a consistent size to each subset of a given set while satisfying the other axioms of a measure, one only finds trivial examples like the counting measure.
Smoker's Paradox Renal Smoker's_Paradox > Health effects of smoking > Renal In addition to increasing the risk of kidney cancer, smoking can also contribute to additional renal damage. Smokers are at a significantly increased risk for chronic kidney disease than non-smokers. A history of smoking encourages the progression of diabetic nephropathy.
HIV superinfection Summary HIV_superinfection HIV superinfection (also called HIV reinfection or SuperAIDS) is a condition in which a person with an established human immunodeficiency virus infection acquires a second strain of HIV, often of a different subtype. These can form a recombinant strain that co-exists with the strain from the initial infection, as well from reinfection with a new virus strain, and may cause more rapid disease progression or carry multiple resistances to certain HIV medications. HIV superinfection may be interclade, where the second infecting virus is phylogenetically distinct from the initial virus, or intraclade, where the two strains are monophyletic.People with HIV risk superinfection by the same actions that would place a non-infected person at risk of acquiring HIV. These include sharing needles and forgoing condoms with HIV-positive sexual partners.
Principal components PCA and information theory Characteristic_vector_analysis > Properties and limitations of PCA > PCA and information theory {\displaystyle I(\mathbf {x} ;\mathbf {s} )-I(\mathbf {y} ;\mathbf {s} ).} The optimality of PCA is also preserved if the noise n {\displaystyle \mathbf {n} } is iid and at least more Gaussian (in terms of the Kullback–Leibler divergence) than the information-bearing signal s {\displaystyle \mathbf {s} } . In general, even if the above signal model holds, PCA loses its information-theoretic optimality as soon as the noise n {\displaystyle \mathbf {n} } becomes dependent.
Meiotic recombination checkpoint Role in cell cycle progression Meiotic_recombination_checkpoint > Meiosis-specific Transcription factor Ndt80 > Role in cell cycle progression NDt80 is crucial for the completion of prophase and entry into meiosis 1, as it stimulates the expression of a large number of middle meiotic genes. Ndt80 is regulated through transcriptional and post-translational mechanisms (i.e. phosphorylation).
Salt bridge (protein and supramolecular) Salt bridges in chemical bonding Salt_bridge_(protein_and_supramolecular) > Salt bridges in chemical bonding The Bjerrum or the Fuoss equation describe ion pair association as function of the ion charges zA and zB and the dielectric constant ε of the medium; a corresponding plot of the stability ΔG vs. zAzB shows for over 200 ion pairs the expected linear correlation for a large variety of ions. Inorganic as well as organic ions display at moderate ionic strength I similar salt bridge association ΔG values around 5 to 6 kJ/mol for a 1:1 combination of anion and cation, almost independent of the nature (size, polarizability etc) of the ions. The ΔG values are additive and approximately a linear function of the charges, the interaction of e.g. a doubly charged phosphate anion with a single charged ammonium cation accounts for about 2x5 = 10 kJ/mol. The ΔG values depend on the ionic strength I of the solution, as described by the Debye-Hückel equation, at zero ionic strength one observes ΔG = 8 kJ/mol. The stabilities of the alkali-ion pairs as function of the anion charge z by can be described by a more detailed equation.
Relational Model Application to databases Relational_data_model > Topics > Application to databases A table data structure is specified as a list of column definitions, each of which specifies a unique column name and the type of the values that are permitted for that column. An attribute value is the entry in a specific column and row, such as "John Doe" or "35". A tuple is basically the same thing as a row, except in an SQL DBMS, where the column values in a row are ordered.