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Index term Summary Index_term In information retrieval, an index term (also known as subject term, subject heading, descriptor, or keyword) is a term that captures the essence of the topic of a document. Index terms make up a controlled vocabulary for use in bibliographic records. They are an integral part of bibliographic control, which is the function by which libraries collect, organize and disseminate documents. They are used as keywords to retrieve documents in an information system, for instance, a catalog or a search engine.
Prime divisor Primality of one Prime_divisor > History > Primality of one For example, the fundamental theorem of arithmetic would need to be rephrased in terms of factorizations into primes greater than 1, because every number would have multiple factorizations with any number of copies of 1. Similarly, the sieve of Eratosthenes would not work correctly if it handled 1 as a prime, because it would eliminate all multiples of 1 (that is, all other numbers) and output only the single number 1. Some other more technical properties of prime numbers also do not hold for the number 1: for instance, the formulas for Euler's totient function or for the sum of divisors function are different for prime numbers than they are for 1. By the early 20th century, mathematicians began to agree that 1 should not be listed as prime, but rather in its own special category as a "unit".
Comparison of programming paradigms Language support Comparison_of_programming_paradigms > Language support Moreover, the specialized syntax works to emphasize the object-oriented approach. Similarly, functions and looping syntax in C (and other procedural and structured programming languages) could be considered syntactic sugar. Assembly language can support procedural or structured programming via its facilities for modifying register values and branching execution depending on program state.
Circuit topology (electrical) Circuit diagrams Circuit_topology_(electrical) > Circuit diagrams The circuit diagrams in this article follow the usual conventions in electronics; lines represent conductors, filled small circles represent junctions of conductors, and open small circles represent terminals for connection to the outside world. In most cases, impedances are represented by rectangles. A practical circuit diagram would use the specific symbols for resistors, inductors, capacitors etc., but topology is not concerned with the type of component in the network, so the symbol for a general impedance has been used instead. The Graph theory section of this article gives an alternative method of representing networks.
SAMPL Challenge Funding SAMPL_Challenge > Funding Currently challenges and workshops are run in partnership with the NIH-funded Drug Design Data Resource, but this will likely change over time as funding for the two projects is not coupled. Funding also allowed a broadening of scope of SAMPL; through SAMPL6, its role had been seen as primarily focused on physical properties, with D3R handling protein-ligand challenges. However, the funded effort broadened its focus to include systems which will drive improvements in modeling, including potentially suitable protein-ligand systems. This is still in contrast to D3R, which relies on donated datasets of pharmaceutical interest, whereas SAMPL challenges are specifically designed to focus on specific modeling challenges.
Inductive probability Generalization and specialization Inductive_probability > Boolean inductive inference > Generalization and specialization The Linnaen classification of living things and objects forms the basis for generalization and specification. The ability to identify, recognize and classify is the basis for generalization. Perceiving the world as a collection of objects appears to be a key aspect of human intelligence.
Wang and Landau algorithm Wang and Landau molecular dynamics: Statistical Temperature Molecular Dynamics (STMD) Wang_and_Landau_algorithm > Wang and Landau molecular dynamics: Statistical Temperature Molecular Dynamics (STMD) The details are given in Ref. With an initial guess for T ( E ) {\displaystyle T(E)} and the range restricted to lie between T L {\displaystyle T_{L}} and T U {\displaystyle T_{U}} , the simulation proceeds as in WLMC, with significant numerical differences. An interpolation of T ~ ( E ) {\displaystyle {\tilde {T}}(E)} gives a continuum expression of the estimated S ( E ) {\displaystyle S(E)} upon integration of its inverse, allowing the use of larger energy bins than in WL.
Satellite Internet access Geostationary orbits Satellite_Internet > Challenges and limitations > Signal latency > Geostationary orbits A geostationary orbit (or geostationary Earth orbit/GEO) is a geosynchronous orbit directly above the Earth's equator (0° latitude), with a period equal to the Earth's rotational period and an orbital eccentricity of approximately zero (i.e. a "circular orbit"). An object in a geostationary orbit appears motionless, at a fixed position in the sky, to ground observers. Launchers often place communications satellites and weather satellites in geostationary orbits, so that the satellite antennas that communicate with them do not have to move to track them, but can point permanently at the position in the sky where the satellites stay. Due to the constant 0° latitude and circularity of geostationary orbits, satellites in GEO differ in location by longitude only.
Design for manufacturability Design and shape Design_for_manufacturability > For CNC machining > Design and shape As machining is a subtractive process, the time to remove the material is a major factor in determining the machining cost. The volume and shape of the material to be removed as well as how fast the tools can be fed will determine the machining time. When using milling cutters, the strength and stiffness of the tool which is determined in part by the length to diameter ratio of the tool will play the largest role in determining that speed. The shorter the tool is relative to its diameter the faster it can be fed through the material.
Human intelligence PASS theory of intelligence Human_intelligence > Theories > PASS theory of intelligence Attention and arousal are combined functions of the frontal lobe and the lower parts of the cortex, although the parietal lobes are also involved in attention as well. Simultaneous processing and Successive processing occur in the posterior region or the back of the brain. Simultaneous processing is broadly associated with the occipital and the parietal lobes while Successive processing is broadly associated with the frontal-temporal lobes. The PASS theory is heavily indebted both to Luria and to studies in cognitive psychology involved in promoting a better look at intelligence.
Multi-armed bandit Empirical motivation Multi-armed_bandit > Empirical motivation The multi-armed bandit problem models an agent that simultaneously attempts to acquire new knowledge (called "exploration") and optimize their decisions based on existing knowledge (called "exploitation"). The agent attempts to balance these competing tasks in order to maximize their total value over the period of time considered. There are many practical applications of the bandit model, for example: clinical trials investigating the effects of different experimental treatments while minimizing patient losses, adaptive routing efforts for minimizing delays in a network, financial portfolio designIn these practical examples, the problem requires balancing reward maximization based on the knowledge already acquired with attempting new actions to further increase knowledge. This is known as the exploitation vs. exploration tradeoff in machine learning. The model has also been used to control dynamic allocation of resources to different projects, answering the question of which project to work on, given uncertainty about the difficulty and payoff of each possibility.Originally considered by Allied scientists in World War II, it proved so intractable that, according to Peter Whittle, the problem was proposed to be dropped over Germany so that German scientists could also waste their time on it.The version of the problem now commonly analyzed was formulated by Herbert Robbins in 1952.
Parallel programming language Instruction-level parallelism Parallel_programming > Types of parallelism > Instruction-level parallelism A computer program is, in essence, a stream of instructions executed by a processor. Without instruction-level parallelism, a processor can only issue less than one instruction per clock cycle (IPC < 1). These processors are known as subscalar processors. These instructions can be re-ordered and combined into groups which are then executed in parallel without changing the result of the program.
History of molecular biology The modern era: the age of RNA structural biology History_of_molecular_biology > History of RNA tertiary structure > The modern era: the age of RNA structural biology The resurgence of RNA structural biology in the mid-1990s has caused a veritable explosion in the field of nucleic acid structural research. Since the publication of the hammerhead and P4-6 structures, numerous major contributions to the field have been made. Some of the most noteworthy examples include the structures of the Group I and Group II introns, and the Ribosome solved by Nenad Ban and colleagues in the laboratory of Thomas Steitz. The first three structures were produced using in vitro transcription, and that NMR has played a role in investigating partial components of all four structures - testaments to the indispensability of both techniques for RNA research. Most recently, the 2009 Nobel Prize in Chemistry was awarded to Ada Yonath, Venkatraman Ramakrishnan and Thomas Steitz for their structural work on the ribosome, demonstrating the prominent role RNA structural biology has taken in modern molecular biology.
Autoimmune adrenalitis Testing Addison_disease > Diagnosis > Testing In suspected cases of Addison's disease, demonstration of low adrenal hormone levels even after appropriate stimulation (called the ACTH stimulation test or synacthen test) with synthetic pituitary ACTH hormone tetracosactide is needed for the diagnosis. Two tests are performed, the short and the long test. Dexamethasone does not cross-react with the assay and can be administered concomitantly during testing.The short test compares blood cortisol levels before and after 250 micrograms of tetracosactide (intramuscular or intravenous) is given. If one hour later, plasma cortisol exceeds 170 nmol/L and has risen by at least 330 nmol/L to at least 690 nmol/L, adrenal failure is excluded.
Periodic table (crystal structure) Close packed metal structures Double_hexagonal_close_packed > Usual crystal structures > Close packed metal structures Many metals adopt close packed structures i.e. hexagonal close packed and face-centred cubic structures (cubic close packed). A simple model for both of these is to assume that the metal atoms are spherical and are packed together in the most efficient way (close packing or closest packing). In closest packing every atom has 12 equidistant nearest neighbours, and therefore a coordination number of 12.
ACID Distributed transactions ACID > Implementation > Distributed transactions Guaranteeing ACID properties in a distributed transaction across a distributed database, where no single node is responsible for all data affecting a transaction, presents additional complications. Network connections might fail, or one node might successfully complete its part of the transaction and then be required to roll back its changes because of a failure on another node. The two-phase commit protocol (not to be confused with two-phase locking) provides atomicity for distributed transactions to ensure that each participant in the transaction agrees on whether the transaction should be committed or not. Briefly, in the first phase, one node (the coordinator) interrogates the other nodes (the participants), and only when all reply that they are prepared does the coordinator, in the second phase, formalize the transaction.
David Hume Induction and causation David_Hume > Writings > Induction and causation In the Critical Phase, Hume denies his predecessors' theories of causation. Next, he uses the Constructive Phase to resolve any doubts the reader may have had while observing the Critical Phase. "Habit or Custom" mends the gaps in reasoning that occur without the human mind even realising it.
Internet Governance Background Internet_Governance > Background This seeks to create a globally unified namespace to ensure the global reach of the Internet. ICANN is governed by an international board of directors drawn from across the Internet's technical, business, academic, and other non-commercial communities.
Fock matrix Summary Fock_matrix In the Hartree–Fock method of quantum mechanics, the Fock matrix is a matrix approximating the single-electron energy operator of a given quantum system in a given set of basis vectors. It is most often formed in computational chemistry when attempting to solve the Roothaan equations for an atomic or molecular system. The Fock matrix is actually an approximation to the true Hamiltonian operator of the quantum system. It includes the effects of electron-electron repulsion only in an average way.
Hybrizyme Mutation Hybrizyme > Mutational origin > Mutation Under the mutational hypothesis, hybrizymes likely arise due to simple point mutations. Sequencing data have indicated this and imply low likelihood that hybrizymes arise as a result of transposition or recombination. Research on pocket gophers and Japanese freshwater crabs confirms that the phenomenon is possibly caused by simple nucleotide substitutions. However, the hypothesis has several weaknesses. It does not explain why normally rare alleles are restricted to a hybrid zone, why polymorphic loci are affected more or offers a mechanism that explains the high frequency of even the rarest variants.
MO diagram Diboron Molecular_orbital_diagram > Diatomic MO diagrams > Diboron The other two p-orbitals, py and px, can overlap side-on. The resulting bonding orbital has its electron density in the shape of two lobes above and below the plane of the molecule. The orbital is not symmetric around the molecular axis and is therefore a pi orbital.
Kundu equation Properties and applications Kundu_equation > Properties and applications The Kundu equation is a completely integrable system, allowing Lax pair representation, exact solutions, and higher conserved quantity. Along with its different particular cases, this equation has been investigated for finding its exact travelling wave solutions, exact solitary wave solutions via bilinearization, and Darboux transformation together with the orbital stability for such solitary wave solutions.The Kundu equation has been applied to various physical processes such as fluid dynamics, plasma physics, and nonlinear optics. It is linked to the mixed nonlinear Schrödinger equation through a gauge transformation and is reducible to a variety of known integrable equations such as the nonlinear Schrödinger equation (NLSE), derivative NLSE, higher nonlinear derivative NLSE, Chen–Lee–Liu, Gerjikov-Vanov, and Kundu–Eckhaus equations, for different choices of the parameters.
Glossary of BitTorrent terms Peer Share_ratio > Terms > Peer A peer is one instance of a BitTorrent client running on a computer on the Internet to which other clients connect and transfer data. Depending on context, "peer" can refer either to any client in the swarm or more specifically to a downloader, a client that has only parts of the file.
Banach Spaces Summary Banach_space In mathematics, more specifically in functional analysis, a Banach space (pronounced ) is a complete normed vector space. Thus, a Banach space is a vector space with a metric that allows the computation of vector length and distance between vectors and is complete in the sense that a Cauchy sequence of vectors always converges to a well-defined limit that is within the space. Banach spaces are named after the Polish mathematician Stefan Banach, who introduced this concept and studied it systematically in 1920–1922 along with Hans Hahn and Eduard Helly.Maurice René Fréchet was the first to use the term "Banach space" and Banach in turn then coined the term "Fréchet space". Banach spaces originally grew out of the study of function spaces by Hilbert, Fréchet, and Riesz earlier in the century. Banach spaces play a central role in functional analysis. In other areas of analysis, the spaces under study are often Banach spaces.
Rectangle method Summary Riemann_sums In mathematics, a Riemann sum is a certain kind of approximation of an integral by a finite sum. It is named after nineteenth century German mathematician Bernhard Riemann. One very common application is approximating the area of functions or lines on a graph, but also the length of curves and other approximations. The sum is calculated by partitioning the region into shapes (rectangles, trapezoids, parabolas, or cubics) that together form a region that is similar to the region being measured, then calculating the area for each of these shapes, and finally adding all of these small areas together.
AC/DC receiver design Transformer AC/DC_receiver_design > Applicability to early radio and television > Transformer Consequently equipment was made with no metal connected to the chassis exposed even in predictable abnormal situations, such as when a plastic knob came off a metal shaft, or small fingers poked through ventilation holes. Service personnel working on energized equipment had to use an isolation transformer for safety, or be mindful that the chassis could be live. AC-only vacuum tube equipment used a bulky, heavy, and expensive transformer, but the chassis was not connected to the supply conductors and could be earthed, making for safe operation.
Chain-driven sprocket Chain standards Roller_chain > Chain standards Chains are sold according to the number of speeds they are designed to work with, for example, "10 speed chain". Hub gear or single speed bicycles use 1/2 x 1/8 inch chains, where 1/8 inch refers to the maximum thickness of a sprocket that can be used with the chain. Typically chains with parallel shaped links have an even number of links, with each narrow link followed by a broad one. Chains built up with a uniform type of link, narrow at one and broad at the other end, can be made with an odd number of links, which can be an advantage to adapt to a special chainwheel-distance; on the other side such a chain tends to be not so strong. Roller chains made using ISO standard are sometimes called "isochains".
Signal programming Synchronous signal programming Signal_programming > Synchronous signal programming In software development, a signal can mean synchronous events (sequences of samples, video frames, etc., with constant sample rate or frame rate) rather than asynchronous events, while the word event and data flow is often used for asynchronous event queues, but this is by no means universal. This language was created in the 1950s Konrad Zuse. Especially in telecommunications, electrical engineering and signal processing, a digital signal is a sampled representation of an analog physical entity. In telecommunications, the term signalling means asynchronous phone call metadata information exchange, for example of telephone numbers. One application of synchronous signal programming is observer pattern.
Positive linear functional Sufficient conditions for continuity of all positive linear functionals Positive_linear_functional > Sufficient conditions for continuity of all positive linear functionals X {\displaystyle X} is complete and metrizable and X = C − C . {\displaystyle X=C-C.} X {\displaystyle X} is bornological and C {\displaystyle C} is a semi-complete strict B {\displaystyle {\mathcal {B}}} -cone in X .
MO diagram Dioxygen Molecular_orbital_diagram > Diatomic MO diagrams > Dioxygen MO treatment of dioxygen is different from that of the previous diatomic molecules because the pσ MO is now lower in energy than the 2π orbitals. This is attributed to interaction between the 2s MO and the 2pz MO. Distributing 8 electrons over 6 molecular orbitals leaves the final two electrons as a degenerate pair in the 2pπ* antibonding orbitals resulting in a bond order of 2.
Bosque (journal) Summary Bosque_(journal) From 1985 to 2003 it was issued twice a year and from 2003 on three times a year. The topics covered in Bosque are management and production of forestry resources, wood science and technology, silviculture, forest ecology, natural resources conservation, and rural development associated with forest ecosystems.
Solar cars Summary Solar_car In January 2023 the company halted vehicle manufacture and sales, and the vehicle maker's production company, Atlas Technologies B.V., requested bankruptcy protection.The Aptera's production is expected to start in 2024.Solar cars depend on a solar array that uses photovoltaic cells (PV cells) to convert sunlight into electricity. Unlike solar thermal energy which converts solar energy to heat, PV cells directly convert sunlight into electricity. When sunlight (photons) strike PV cells, they excite electrons and allow them to flow, creating an electric current. PV cells are made of semiconductor materials such as silicon and alloys of indium, gallium and nitrogen. Crystalline silicon is the most common material used and has an efficiency rate of 15–25%.
Progestogen (medication) Birth control Progestogen_(medication) > Side effects > Mood changes > Birth control The progestins assessed included depot medroxyprogesterone acetate, levonorgestrel-containing contraceptive implants and intrauterine devices, and progestogen-only birth control pills. Findings of large observational studies are mixed due to prominent confounding factors, but overall show no association of hormonal birth control with depression.
Industrial scale General and cited references Economies_of_scale > References > General and cited references Principles of Economics (8 ed.). London: Macmillan. Repr.
Glossary of electrical and electronics engineering P Glossary_of_electrical_and_electronics_engineering > P process controlThe field of study of automatic control of processes. programmable logic controllerA computer system designed to be rugged enough for industrial use and with a programming environment highly tuned to the domain of industrial control problems. programming languageA formalism for human-readable instructions to a computer.
Timeline of quantum computing and communication 2008 Timeline_of_quantum_computing_and_communication > 2000s > 2008 Electron position was controlled in a silicon circuit. A superconducting electronic circuit pumped microwave photons. Amplitude spectroscopy was developed.
Knife-edge effect "Knife edge" Diffraction_pattern > Examples > "Knife edge" The knife-edge effect or knife-edge diffraction is a truncation of a portion of the incident radiation that strikes a sharp well-defined obstacle, such as a mountain range or the wall of a building. The knife-edge effect is explained by the Huygens–Fresnel principle, which states that a well-defined obstruction to an electromagnetic wave acts as a secondary source, and creates a new wavefront. This new wavefront propagates into the geometric shadow area of the obstacle.
Prajmaline Mechanism Prajmaline > Mechanism Prajmaline causes a resting block in the heart. A resting block is the depression of a person's Vmax after a resting period. This effect is seen more in the atrium than the ventricle.
Evaporator coil Marine Evaporator > Uses > Marine Evaporators are usually of the shell-and-tube type (known as an Atlas Plant) or of the plate type (such as the type designed by Alfa Laval). Temperature, production and vacuum are controlled by regulating the system valves. Seawater temperature can interfere with production, as can fluctuations in engine load. For this reason, the evaporator is adjusted as seawater temperature changes and shuts down altogether when the ship is maneuvering. An alternative in some vessels, such as naval ships and passenger ships, is the use of the reverse osmosis principle for fresh-water production instead of using evaporators.
Apomixis Some related terms Apomixis > Some related terms The second process that is referred to as androgenesis or androclinesis involves (artificial) culture of haploid plants from anther tissue or microspores. Androgenesis has also been artificially induced in fish.Apogamy: Although this term was (before 1908) used for other types of apomixis, and then discarded as too confusing, it is still sometimes used when an embryo develops from a cell of the megagametophyte other than the egg cell. In flowering plants, the cells involved in apogamy would be synergids or antipodal cells.
Lung biopsy Types Lung_biopsy > Types A lung biopsy can be performed percutaneously (through the skin, typically guided by a CT Scan), via bronchoscopy with ultrasound guidance, or by surgery, either open or by video-assisted thoracoscopic surgery (VATS).
Gram-Schmidt theorem Summary Gram–Schmidt_decomposition In mathematics, particularly linear algebra and numerical analysis, the Gram–Schmidt process or Gram-Schmidt algorithm is a method for orthonormalizing a set of vectors in an inner product space, most commonly the Euclidean space Rn equipped with the standard inner product. The Gram–Schmidt process takes a finite, linearly independent set of vectors S = {v1, ..., vk} for k ≤ n and generates an orthogonal set S′ = {u1, ..., uk} that spans the same k-dimensional subspace of Rn as S. The method is named after Jørgen Pedersen Gram and Erhard Schmidt, but Pierre-Simon Laplace had been familiar with it before Gram and Schmidt. In the theory of Lie group decompositions, it is generalized by the Iwasawa decomposition. The application of the Gram–Schmidt process to the column vectors of a full column rank matrix yields the QR decomposition (it is decomposed into an orthogonal and a triangular matrix).
Flat (geometry) By equations Euclidean_subspace > Descriptions > By equations A flat can be described by a system of linear equations. For example, a line in two-dimensional space can be described by a single linear equation involving x and y: 3 x + 5 y = 8. {\displaystyle 3x+5y=8.}
Cancer metastasis Metastasis and primary cancer Metastatic_relapse > Pathophysiology > Metastasis and primary cancer It is theorized that metastasis always coincides with a primary cancer, and, as such, is a tumor that started from a cancer cell or cells in another part of the body. However, over 10% of patients presenting to oncology units will have metastases without a primary tumor found. In these cases, doctors refer to the primary tumor as "unknown" or "occult," and the patient is said to have cancer of unknown primary origin (CUP) or unknown primary tumors (UPT). It is estimated that 3% of all cancers are of unknown primary origin.
Covariance and contravariance of vectors Algebra and geometry Covariant_vector > Algebra and geometry Likewise, vectors whose components are contravariant push forward under smooth mappings, so the operation assigning the space of (contravariant) vectors to a smooth manifold is a covariant functor. Secondly, in the classical approach to differential geometry, it is not bases of the tangent bundle that are the most primitive object, but rather changes in the coordinate system. Vectors with contravariant components transform in the same way as changes in the coordinates (because these actually change oppositely to the induced change of basis). Likewise, vectors with covariant components transform in the opposite way as changes in the coordinates.
Eigenspinor Properties Eigenspinor > Properties Each set of eigenspinors forms a complete, orthonormal basis. This means that any state can be written as a linear combination of the basis spinors. The eigenspinors are eigenvectors of the Pauli matrices in the case of a single spin 1/2 particle.
CAD software 3D CAD Computer_aided_geometric_design > Types > 3D CAD 3D wireframe is basically an extension of 2D drafting (not often used today) into a three-dimensional space. Each line has to be manually inserted into the drawing. The final product has no mass properties associated with it and cannot have features directly add to it, such as holes. The operator approaches these in a similar fashion to the 2D systems, although many 3D systems allow using the wireframe model to make the final engineering drawing views.
Discovery science Methodology Discovery_science > Methodology Researchers hope that combining integrative analyses of data from a range of different levels can result in new classification approaches to enable personalised interventions. Some biologists, such as Leroy Hood, have suggested that the model of ‘discovery science’ is a model which certain research fields are heading towards. For example, it is believed that more information about gene function can be discovered, through the evolution of data-mining tools.Discovery-based approaches are often referred to as “big data” approaches, because of the large-scale datasets that they involve analyses of.
Contributions of Leonhard Euler to mathematics Complex analysis Contributions_of_Leonhard_Euler_to_mathematics > Complex analysis This has been called "the most remarkable formula in mathematics" by Richard Feynman. Euler's identity is a special case of this: e i π + 1 = 0 . {\displaystyle e^{i\pi }+1=0\,.} This identity is particularly remarkable as it involves e, π {\displaystyle \pi } , i, 1, and 0, arguably the five most important constants in mathematics.
Electron configurations of the elements (data page) Hoffman, Lee, and Pershina Electron_configurations_of_the_elements_(data_page) > References > Hoffman, Lee, and Pershina Hoffman, Darleane C.; Lee, Diana M.; Pershina, Valeria (2006). "Transactinides and the future elements". In Morss; Edelstein, Norman M.; Fuger, Jean (eds.). The Chemistry of the Actinide and Transactinide Elements (3rd ed.).
PDZ domain PDZ proteins PDZ_domain > PDZ proteins Three of the most well documented PDZ proteins are PSD-95, GRIP, and HOMER. PSD-95 is a brain synaptic protein with three PDZ domains, each with unique properties and structures that allow PSD-95 to function in many ways. In general, the first two PDZ domains interact with receptors and the third interacts with cytoskeleton-related proteins.
Key-value data Self-balancing binary search trees Associative_array > Implementation > Tree implementations > Self-balancing binary search trees Another common approach is to implement an associative array with a self-balancing binary search tree, such as an AVL tree or a red–black tree.Compared to hash tables, these structures have both advantages and weaknesses. The worst-case performance of self-balancing binary search trees is significantly better than that of a hash table, with a time complexity in big O notation of O(log n). This is in contrast to hash tables, whose worst-case performance involves all elements sharing a single bucket, resulting in O(n) time complexity. In addition, and like all binary search trees, self-balancing binary search trees keep their elements in order.
Bloom filters Distributed Bloom filters Bloom_filter > Extensions and applications > Distributed Bloom filters All elements that didn't have their hash sent back are now guaranteed to not be a duplicate and won't be evaluated further, for the remaining elements a Repartitioning algorithm can be used. First all the elements that had their hash value sent back are sent to the PE that their hash is responsible for. Any element and its duplicate is now guaranteed to be on the same PE.
Proto-satellite disk Summary Satellite_system_(astronomy) A satellite system is a set of gravitationally bound objects in orbit around a planetary mass object (incl. sub-brown dwarfs and rogue planets) or minor planet, or its barycenter. Generally speaking, it is a set of natural satellites (moons), although such systems may also consist of bodies such as circumplanetary disks, ring systems, moonlets, minor-planet moons and artificial satellites any of which may themselves have satellite systems of their own (see Subsatellites).
Formal parameter Example Function_parameter > Example The following program in the C programming language defines a function that is named "SalesTax" and has one parameter named "price". The type of price is "double" (i.e. a double-precision floating point number). The function's return type is also a double. After the function has been defined, it can be invoked as follows: In this example, the function has been invoked with the argument 10.00.
Jumping genes Evolution Controlling_element > Evolution Although both types are inactive, one copy of Hsmar1 found in the SETMAR gene is under selection as it provides DNA-binding for the histone-modifying protein. Many other human genes are similarly derived from transposons. Hsmar2 has been reconstructed multiple times from the fossil sequences.Large quantities of TEs within genomes may still present evolutionary advantages, however.
Hemerythrin O2 binding mechanism Hemerythrin > O2 binding mechanism The mechanism of dioxygen binding is unusual. Most O2 carriers operate via formation of dioxygen complexes, but hemerythrin holds the O2 as a hydroperoxide (HO2, or -OOH−). The site that binds O2 consists of a pair of iron centres. The iron atoms are bound to the protein through the carboxylate side chains of a glutamate and aspartates as well as through five histidine residues.
Pseudo-polynomial time Summary Pseudo-polynomial_time In computational complexity theory, a numeric algorithm runs in pseudo-polynomial time if its running time is a polynomial in the numeric value of the input (the largest integer present in the input)—but not necessarily in the length of the input (the number of bits required to represent it), which is the case for polynomial time algorithms.In general, the numeric value of the input is exponential in the input length, which is why a pseudo-polynomial time algorithm does not necessarily run in polynomial time with respect to the input length. An NP-complete problem with known pseudo-polynomial time algorithms is called weakly NP-complete. An NP-complete problem is called strongly NP-complete if it is proven that it cannot be solved by a pseudo-polynomial time algorithm unless P = NP. The strong/weak kinds of NP-hardness are defined analogously.
Microbial cooperation Introduction Microbial_cooperation > Introduction A cooperative interaction benefits a recipient, and is selected for on that basis. In microbial systems, cells belonging to the same taxa have been documented partaking in cooperative interactions to perform a wide range of complex multicellular behaviors such as dispersal, foraging, construction of biofilms, reproduction, chemical warfare, and signaling. This article will outline the various forms of cooperative interactions seen in microbial systems, as well as the benefits that might have driven the evolution of these complex behaviors.
Cancer Staging Solid Cancer_Staging > Systems > Solid For solid tumors, TNM is by far the most commonly used system, but it has been adapted for some conditions. Breast cancer: In breast cancer classification, staging is usually based on TNM, but staging in I–IV may be used as well. Cervical and ovarian cancers: the "FIGO" system has been adopted into the TNM system. For premalignant dysplastic changes, the CIN (cervical intraepithelial neoplasia) grading system is used.
Genetic correlations Summary Genetic_correlations Genetic correlations have been found to be common in non-human genetics and to be broadly similar to their respective phenotypic correlations, and also found extensively in human traits, dubbed the 'phenome'.This finding of widespread pleiotropy has implications for artificial selection in agriculture, interpretation of phenotypic correlations, social inequality, attempts to use Mendelian randomization in causal inference, the understanding of the biological origins of complex traits, and the design of GWASes. A genetic correlation is to be contrasted with environmental correlation between the environments affecting two traits (e.g. if poor nutrition in a household caused both lower IQ and height); a genetic correlation between two traits can contribute to the observed (phenotypic) correlation between two traits, but genetic correlations can also be opposite observed phenotypic correlations if the environment correlation is sufficiently strong in the other direction, perhaps due to tradeoffs or specialization. The observation that genetic correlations usually mirror phenotypic correlations is known as "Cheverud's Conjecture" and has been confirmed in animals and humans, and showed they are of similar sizes; for example, in the UK Biobank, of 118 continuous human traits, only 29% of their intercorrelations have opposite signs, and a later analysis of 17 high-quality UKBB traits reported correlation near-unity.
Adaptation Summary Selective_advantage Adaptation is related to biological fitness, which governs the rate of evolution as measured by change in allele frequencies. Often, two or more species co-adapt and co-evolve as they develop adaptations that interlock with those of the other species, such as with flowering plants and pollinating insects. In mimicry, species evolve to resemble other species; in Müllerian mimicry this is a mutually beneficial co-evolution as each of a group of strongly defended species (such as wasps able to sting) come to advertise their defenses in the same way.
Energy accounting Energy balance Energy_accounting > Energy balance Energy returned on energy invested (EROEI) is the ratio of energy delivered by an energy technology to the energy invested to set up the technology.
Declarative language Definition Declarative_programming > Definition Any programming language that lacks side effects (or more specifically, is referentially transparent) A language with a clear correspondence to mathematical logic.These definitions overlap substantially. Declarative programming is a non-imperative style of programming in which programs describe their desired results without explicitly listing commands or steps that must be performed. Functional and logic programming languages are characterized by a declarative programming style.
Service-oriented programming Summary Service-oriented_programming While SOA focuses on communication between systems using "services", SOP provides a new technique to build agile application modules using in-memory services as the unit of work. An in-memory service in SOP can be transparently externalized as a web service operation. Due to language and platform independent Web Service standards, SOP embraces all existing programming paradigms, languages and platforms.
Information engineering Cheminformatics Information_engineering > Elements > Cheminformatics Cheminformatics is the field that deals with the analysis, processing, and use of chemical data.
Nernst–Planck equation Summary Nernst–Planck_equation The Nernst–Planck equation is a conservation of mass equation used to describe the motion of a charged chemical species in a fluid medium. It extends Fick's law of diffusion for the case where the diffusing particles are also moved with respect to the fluid by electrostatic forces. It is named after Walther Nernst and Max Planck.
Glucose intolerance Fasting Insulin Glucose_intolerance > Diagnosis > Fasting Insulin Hyperinsulinemia due to insulin resistance may occur in individuals with normal glucose levels and therefore is not diagnosed with usual tests. Hyperinsulinemia precedes prediabetes and diabetes that are characterized by hyperglycemia. Insulin resistance can be diagnosed by measures of plasma insulin, both fasting or during a glucose tolerance test. The use of fasting insulin to identify patients at risk has been proposed, but is currently not commonly used in clinical practice.The implications of hyperinsulinemia is the risk of comorbidities related to diabetes that may precede changes in blood glucose, including cardiovascular diseases.
Cellular replication Elongation Lagging_strand > Replication process > Elongation DNA polymerase has 5′–3′ activity. All known DNA replication systems require a free 3′ hydroxyl group before synthesis can be initiated (note: the DNA template is read in 3′ to 5′ direction whereas a new strand is synthesized in the 5′ to 3′ direction—this is often confused). Four distinct mechanisms for DNA synthesis are recognized: All cellular life forms and many DNA viruses, phages and plasmids use a primase to synthesize a short RNA primer with a free 3′ OH group which is subsequently elongated by a DNA polymerase. The retroelements (including retroviruses) employ a transfer RNA that primes DNA replication by providing a free 3′ OH that is used for elongation by the reverse transcriptase.
Laser absorption spectroscopy Laser absorption spectrometry using fundamental vibrational or electronic transitions Laser_absorption_spectrometry > Laser absorption spectrometry using fundamental vibrational or electronic transitions The second way of improving the detection limit of LAS is to employ transitions with larger line strength, either in the fundamental vibrational band or electronic transitions. The former, which normally reside at ~5 μm, have line strengths that are ~2–3 orders of magnitude higher than those of typical overtone transition. On the other hand, electronic transitions have often yet another 1–2 orders of magnitude larger line strengths. The transitions strengths for the electronic transitions of NO, which are located in the UV range (at ~227 nm) are ~2 orders of magnitude larger than those in the MIR region.The recent development of quantum cascade (QC) lasers working in the MIR region has opened up new possibilities for sensitive detection of molecular species on their fundamental vibrational bands. It is more difficult to generate stable cw light addressing electronic transitions, since these often lie in the UV region.
Quantitative social research Methodological assumptions Quantitative_social_research > Methodological assumptions Propositions are conclusions drawn about the relationships among concepts, based on analysis of axioms. Hypotheses are specified expectations about empirical reality derived from propositions. Social research involves testing these hypotheses to see if they are true.
Inferring horizontal gene transfer Phylogenetic profiles Inferring_horizontal_gene_transfer > Phylogenetic methods > Implicit phylogenetic methods > Phylogenetic profiles A group of orthologous or homologous genes can be analysed in terms of the presence or absence of group members in the reference genomes; such patterns are called phylogenetic profiles. To find HGT events, phylogenetic profiles are scanned for an unusual distribution of genes. Absence of a homolog in some members of a group of closely related species is an indication that the examined gene might have arrived via an HGT event.
DNA vaccination Kinetics of antibody response DNA_immunization > Immune response > Humoral (antibody) response > Kinetics of antibody response DNA vaccine expressing HBV small and middle envelope protein was injected into adults with chronic hepatitis. The vaccine resulted in specific interferon gamma cell production. Also specific T-cells for middle envelop proteins antigens were developed.
Weil's disease Signs and symptoms Weil's_disease > Signs and symptoms The disease begins suddenly with fever accompanied by chills, intense headache, severe muscle aches and abdominal pain. A headache brought on by leptospirosis causes throbbing pain and is characteristically located at the head's bilateral temporal or frontal regions. The person could also have pain behind the eyes and a sensitivity to light.
Neurofibrillary tangles Alzheimer disease with concomitant dementia with Lewy bodies (AD+DLB) Neurofibrillary_tangle > Pathology > Alzheimer disease with concomitant dementia with Lewy bodies (AD+DLB) The degree of NFT involvement in AD is defined by Braak staging. Braak stages I and II are used when NFT involvement is confined mainly to the transentorhinal region of the brain. Stages III and IV are indicated when there is involvement of limbic regions such as the hippocampus, and V and VI when there's extensive neocortical involvement.
Perivascular space Multiple sclerosis Perivascular_space > Current research > Association of dilated VRS and other diseases > Multiple sclerosis Similar to the research concerning a potential connection between perivascular spaces and Alzheimer's, MRI scans of people recently diagnosed with multiple sclerosis (MS) have been studied. Larger, more prevalent spaces have been observed in those with MS. Additional studies with similar findings have suggested that the inflammatory cells which contribute to the demyelination that characterizes MS also attack the perivascular spaces. Studies using advanced MRI techniques will be necessary to determine if the perivascular spaces can be implicated as a potential marker of the disease.
The Magnetic Fields History The_Magnetic_Fields > History Most of the synthesizers on the record didn't exist when we were last using synthesizers." The song "Andrew in Drag" garnered much attention, receiving play from entities such as CBS News and NPR's All Songs Considered. In 2012, the Magnetic Fields celebrated its new album by launching a North American and European tour.
Reality bomb Matrix Reality_bomb > M > Matrix The Matrix is a computer system that contains the collective of all Time Lord knowledge. It first appeared in the 1976 serial The Deadly Assassin. The Matrix can only be accessed by the President of the High Council of Time Lords through an item known as the Crown of Rassilon, though a person assuming the role known as the Keeper of the Matrix also holds a key to access it. Access to the Matrix is restricted to most Time Lords.
Pulse (signal processing) Nyquist pulse Pulse_(signal_processing) > Pulse shapes > Nyquist pulse A Nyquist pulse is one which meets the Nyquist ISI criterion and is important in data transmission. An example of a pulse which meets this condition is the sinc function. The sinc pulse is of some significance in signal-processing theory but cannot be produced by a real generator for reasons of causality. In 2013, Nyquist pulses were produced in an effort to reduce the size of pulses in optical fibers, which enables them to be packed 10 times more closely together, yielding a corresponding 10-fold increase in bandwidth. The pulses were more than 99 percent perfect and were produced using a simple laser and modulator.
Spontaneous chiral symmetry breaking In particle physics Spontaneous_symmetry_breaking > In particle physics The symmetry of the equations is not reflected by the individual solutions, but it is reflected by the range of solutions. An actual measurement reflects only one solution, representing a breakdown in the symmetry of the underlying theory. "Hidden" is a better term than "broken", because the symmetry is always there in these equations.
Computable numbers Not computably enumerable Uncomputable_number > Properties > Not computably enumerable While the set of real numbers is uncountable, the set of computable numbers is classically countable and thus almost all real numbers are not computable. Here, for any given computable number x , {\displaystyle x,} the well ordering principle provides that there is a minimal element in S {\displaystyle S} which corresponds to x {\displaystyle x} , and therefore there exists a subset consisting of the minimal elements, on which the map is a bijection. The inverse of this bijection is an injection into the natural numbers of the computable numbers, proving that they are countable. But, again, this subset is not computable, even though the computable reals are themselves ordered.
Impact of the COVID-19 pandemic on neurological, psychological and other mental health outcomes Summary Impact_of_the_COVID-19_pandemic_on_neurological,_psychological_and_other_mental_health_outcomes There is increasing evidence suggesting that COVID-19 causes both acute and chronic neurological or psychological symptoms. Caregivers of COVID-19 patients also show a higher than average prevalence of mental health concerns. These symptoms result from multiple different factors. SARS-Coronavirus-2 (SARS-CoV-2) directly infects olfactory neurons (smell) and nerve cells expressing taste receptors.
Wind generated current Wind driven upwelling Wind_generated_current > Mechanism > Wind driven upwelling When the net Ekman transport along a coastline is offshore, a compensatory inflow is possible from below, which brings up bottom water, which tends to be nutrient rich as it comes from the poorly lit regions where photosynthesis is insignificant. Upwelling at the equator is associated with the Intertropical Convergence Zone (ITCZ) which moves seasonally, and consequently, is often located just north or south of the equator. Easterly trade winds blow from the Northeast and Southeast and converge along the equator blowing West to form the ITCZ. Although there are no Coriolis forces present along the equator, upwelling still occurs just north and south of the equator. This results in a divergence, with denser, nutrient-rich water being upwelled from below.
Crystallography Techniques Crystallographic_planes > Techniques Hence crystallography applies for the most part only to crystals, or to molecules which can be coaxed to crystallize for the sake of measurement. In spite of this, a certain amount of molecular information can be deduced from patterns that are generated by fibers and powders, which while not as perfect as a solid crystal, may exhibit a degree of order. This level of order can be sufficient to deduce the structure of simple molecules, or to determine the coarse features of more complicated molecules. For example, the double-helical structure of DNA was deduced from an X-ray diffraction pattern that had been generated by a fibrous sample.
Sheaf cohomology Higher direct images and the Leray spectral sequence Sheaf_cohomology > Higher direct images and the Leray spectral sequence The special case where f is a fibration and E is a constant sheaf plays an important role in homotopy theory under the name of the Serre spectral sequence. In that case, the higher direct image sheaves are locally constant, with stalks the cohomology groups of the fibers F of f, and so the Serre spectral sequence can be written as E 2 i j = H i ( Y , H j ( F , A ) ) ⇒ H i + j ( X , A ) {\displaystyle E_{2}^{ij}=H^{i}(Y,H^{j}(F,A))\Rightarrow H^{i+j}(X,A)} for an abelian group A. A simple but useful case of the Leray spectral sequence is that for any closed subset X of a topological space Y and any sheaf E on X, writing f: X → Y for the inclusion, there is an isomorphism H i ( Y , f ∗ E ) ≅ H i ( X , E ) . {\displaystyle H^{i}(Y,f_{*}E)\cong H^{i}(X,E).} As a result, any question about sheaf cohomology on a closed subspace can be translated to a question about the direct image sheaf on the ambient space.
C21H18NO4 Summary C21H18NO4 The molecular formula C21H18NO4 (molar mass: 348.37 g/mol, exact mass: 348.1236 u) may refer to: Chelerythrine, an alkaloid Nitidine, an alkaloid
Site specific recombination Summary Site-specific_recombination Many different genome modification strategies, among these recombinase-mediated cassette exchange (RMCE), an advanced approach for the targeted introduction of transcription units into predetermined genomic loci, rely on SSRs. Site-specific recombination systems are highly specific, fast, and efficient, even when faced with complex eukaryotic genomes. They are employed naturally in a variety of cellular processes, including bacterial genome replication, differentiation and pathogenesis, and movement of mobile genetic elements. For the same reasons, they present a potential basis for the development of genetic engineering tools.Recombination sites are typically between 30 and 200 nucleotides in length and consist of two motifs with a partial inverted-repeat symmetry, to which the recombinase binds, and which flank a central crossover sequence at which the recombination takes place. The pairs of sites between which the recombination occurs are usually identical, but there are exceptions (e.g. attP and attB of λ integrase).
Variance (land use) Types Variance_(land_use) > Types Another would be a house built on a sloping lot. If the slope of the lot makes it onerous to comply with the height limit—typically due to the way the municipality's code requires height to be measured—then a variance could be requested for a structure of increased height because of the special conditions on the lot.
Kolmogorov equations (Markov jump process) The equations Kolmogorov_equations_(Markov_jump_process) > The equations For the case of a countable state space we put i , j {\displaystyle i,j} in place of x , y {\displaystyle x,y} . The Kolmogorov forward equations read ∂ P i j ∂ t ( s ; t ) = ∑ k P i k ( s ; t ) A k j ( t ) {\displaystyle {\frac {\partial P_{ij}}{\partial t}}(s;t)=\sum _{k}P_{ik}(s;t)A_{kj}(t)} ,where A ( t ) {\displaystyle A(t)} is the transition rate matrix (also known as the generator matrix), while the Kolmogorov backward equations are ∂ P i j ∂ s ( s ; t ) = − ∑ k P k j ( s ; t ) A i k ( s ) {\displaystyle {\frac {\partial P_{ij}}{\partial s}}(s;t)=-\sum _{k}P_{kj}(s;t)A_{ik}(s)} The functions P i j ( s ; t ) {\displaystyle P_{ij}(s;t)} are continuous and differentiable in both time arguments. They represent the probability that the system that was in state i {\displaystyle i} at time s {\displaystyle s} jumps to state j {\displaystyle j} at some later time t > s {\displaystyle t>s} . The continuous quantities A i j ( t ) {\displaystyle A_{ij}(t)} satisfy A i j ( t ) = u = t , A j k ( t ) ≥ 0 , j ≠ k , ∑ k A j k ( t ) = 0. {\displaystyle A_{ij}(t)=\left_{u=t},\quad A_{jk}(t)\geq 0,\ j\neq k,\quad \sum _{k}A_{jk}(t)=0.}
Toxic injury Signs and symptoms Toxic_injury > Signs and symptoms Depression, severe headaches and dizziness are the symptoms for toxins affecting the spinal cord and brain. Visible reactions such as skin rashes, and swelling and eye redness are common. Exposure to asbestos can lead to Mesothelioma which is a cancer that can cause serious damage to the lining of the lungs. The symptoms include shortness of breath, cough, night sweats and fever.
Risk factors of schizophrenia Hypoxia Risk_factors_of_schizophrenia > Environment > Hypoxia It has been hypothesized since the 1970s that brain hypoxia (low oxygen levels) before, at or immediately after, birth may be a risk factor for the development of schizophrenia.Hypoxia is demonstrated as relevant to schizophrenia in animal models, molecular biology and epidemiology studies. One study was able to differentiate 90% of cases of schizophrenia from controls based on hypoxia and metabolism. Hypoxia has been described as one of the most important of the external factors that influence susceptibility, although studies have been mainly epidemiological. Such studies place a high degree of importance on hypoxic insult, but given the pattern of the illness in some families, they propose a genetic basis as well; stopping short of concluding that hypoxia is a sole cause on its own.
Differentiation of trigonometric functions Differentiating the inverse tangent function Differentiation_of_trigonometric_functions > Proofs of derivatives of inverse trigonometric functions > Differentiating the inverse tangent function We let y = arctan ⁡ x {\displaystyle y=\arctan x\,\!} Where − π 2 < y < π 2 {\displaystyle -{\frac {\pi }{2}}
Hassan Aref Fluid mechanics Hassan_Aref > Notable research > Fluid mechanics Aref was the author of some 80 articles in leading journals in the field of fluid mechanics. He has also authored chapters in several books, edited two collections of papers, and given presentations at conferences and universities around the world. Aref received the 2000 Otto Laporte Award from the American Physical Society for this work and for his work on vortex dynamics for which he is also well known.
Lie group theory The exponential map Real_Lie_group > Basic concepts > The exponential map Every element of G {\displaystyle G} that is sufficiently close to the identity is the exponential of a matrix in the Lie algebra.The definition above is easy to use, but it is not defined for Lie groups that are not matrix groups, and it is not clear that the exponential map of a Lie group does not depend on its representation as a matrix group. We can solve both problems using a more abstract definition of the exponential map that works for all Lie groups, as follows. For each vector X {\displaystyle X} in the Lie algebra g {\displaystyle {\mathfrak {g}}} of G {\displaystyle G} (i.e., the tangent space to G {\displaystyle G} at the identity), one proves that there is a unique one-parameter subgroup c: R → G {\displaystyle c:\mathbb {R} \rightarrow G} such that c ′ ( 0 ) = X {\displaystyle c'(0)=X} .
Electrophilic amination Prevailing mechanisms Electrophilic_amination > Mechanism and stereochemistry > Prevailing mechanisms These intermediates react with carbanions to give substituted amines. Other electron-deficient, sp3 amination reagents react by similar mechanisms to give substitution products. In aminations involving oxaziridines, nucleophilic attack takes place on the nitrogen atom of the three-membered ring.
Stress–strain analysis Factor of safety Stress–strain_analysis > Factor of safety However, the ratio of the allowable stress to the developed stress must be greater than 1.0 as a factor of safety (design factor) will be specified in the design requirement for the structure. All structures are designed to exceed the load those structures are expected to experience during their use. The design factor (a number greater than 1.0) represents the degree of uncertainty in the value of the loads, material strength, and consequences of failure.
Cunningham's rule Summary Cunningham's_rule In mathematical optimization, Cunningham's rule (also known as least recently considered rule or round-robin rule) is an algorithmic refinement of the simplex method for linear optimization. The rule was proposed 1979 by W. H. Cunningham to defeat the deformed hypercube constructions by Klee and Minty et al. (see, e.g. Klee–Minty cube).Cunningham's rule assigns a cyclic order to the variables and remembers the last variable to enter the basis. The next entering variable is chosen to be the first allowable candidate starting from the last chosen variable and following the given circular order.
Johns Hopkins Berman Institute of Bioethics Research Ethics Johns_Hopkins_Berman_Institute_of_Bioethics > Programs > Research Ethics The Program in Research Ethics addresses difficult ethical challenges in research involving human subjects in the U.S. and worldwide. In partnership with faculty of the Brain Sciences Institute, the Bioethics Institute seeks to define ethical questions in the exploration of the structure and function of the brain.
Let-7 microRNA precursor Summary Let-7_microRNA_precursor miRNAs are initially transcribed in long transcripts (up to several hundred nucleotides) called primary miRNAs (pri-miRNAs), which are processed in the nucleus by Drosha and Pasha to hairpin structures of about 70 nucleotide. These precursors (pre-miRNAs) are exported to the cytoplasm by exportin5, where they are subsequently processed by the enzyme Dicer to a ~22 nucleotide mature miRNA. The involvement of Dicer in miRNA processing demonstrates a relationship with the phenomenon of RNA interference.
Exercise (mathematics) Summary Mathematical_exercise The standard exercises of calculus involve finding derivatives and integrals of specified functions. Usually instructors prepare students with worked examples: the exercise is stated, then a model answer is provided. Often several worked examples are demonstrated before students are prepared to attempt exercises on their own. Some texts, such as those in Schaum's Outlines, focus on worked examples rather than theoretical treatment of a mathematical topic.