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Value (computer science) Summary Value_(computer_science) In computer science and software programming, a value is the representation of some entity that can be manipulated by a program. The members of a type are the values of that type.The "value of a variable" is given by the corresponding mapping in the environment. In languages with assignable variables, it becomes necessary to distinguish between the r-value (or contents) and the l-value (or location) of a variable.In declarative (high-level) languages, values have to be referentially transparent. This means that the resulting value is independent of the location of the expression needed to compute the value. Only the contents of the location (the bits, whether they are 1 or 0) and their interpretation are significant.
External variable Definition, declaration and the extern keyword External_variable > Definition, declaration and the extern keyword A variable must be defined exactly once in one of the modules of the program. If there is no definition or more than one, an error is produced, possibly in the linking stage. A variable may be declared many times, as long as the declarations are consistent with each other and with the definition (something which header files facilitate greatly).
Non-standard calculus Uniform continuity Non-standard_calculus > Uniform continuity Concerning quantifier complexity, the following remarks were made by Kevin Houston: The number of quantifiers in a mathematical statement gives a rough measure of the statement’s complexity. Statements involving three or more quantifiers can be difficult to understand. This is the main reason why it is hard to understand the rigorous definitions of limit, convergence, continuity and differentiability in analysis as they have many quantifiers. In fact, it is the alternation of the ∀ {\displaystyle \forall } and ∃ {\displaystyle \exists } that causes the complexity.Andreas Blass wrote as follows: Often ... the nonstandard definition of a concept is simpler than the standard definition (both intuitively simpler and simpler in a technical sense, such as quantifiers over lower types or fewer alternations of quantifiers).
Rational root Third Rational_root_theorem > Examples > Third True roots must occur on both lists, so list of rational root candidates has shrunk to just x = 2 and x = 2/3. If k ≥ 1 rational roots are found, Horner's method will also yield a polynomial of degree n − k whose roots, together with the rational roots, are exactly the roots of the original polynomial. If none of the candidates is a solution, there can be no rational solution.
Microsoft Equation Editor Graph Microsoft_Chart > Graph Microsoft Graph (originally known as Microsoft Chart) is an OLE application deployed by Microsoft Office programs such as Excel and Access to create charts and graphs. The program is available as an OLE application object in Visual Basic. Microsoft Graph supports many different types of charts, but its output is dated. Office 2003 was the last version to use Microsoft Graph for hosting charts inside Office applications as OLE objects.
Quantum Biology Photosynthesis Quantum_Biology > Applications > Photosynthesis FT electron spectroscopy studies of electron absorption and transfer show an efficiency of above 99%, which cannot be explained by classical mechanical models like the diffusion model. Instead, as early as 1938, scientists theorized that quantum coherence was the mechanism for excitation energy transfer. Scientists have recently looked for experimental evidence of this proposed energy transfer mechanism.
Bernoulli's equation Applications Bernoulli’s_principle > Applications Whenever the distribution of speed past the top and bottom surfaces of a wing is known, the lift forces can be calculated (to a good approximation) using Bernoulli's equations, which were established by Bernoulli over a century before the first man-made wings were used for the purpose of flight.The carburetor used in many reciprocating engines contains a venturi to create a region of low pressure to draw fuel into the carburetor and mix it thoroughly with the incoming air. The low pressure in the throat of a venturi can be explained by Bernoulli's principle; in the narrow throat, the air is moving at its fastest speed and therefore it is at its lowest pressure. An injector on a steam locomotive or a static boiler.
Violent relaxation Summary Chandrasekhar_friction In astrophysics, dynamical friction or Chandrasekhar friction, sometimes called gravitational drag, is loss of momentum and kinetic energy of moving bodies through gravitational interactions with surrounding matter in space. It was first discussed in detail by Subrahmanyan Chandrasekhar in 1943.
Coverage probability Concept Coverage_probability > Concept A discrepancy between the coverage probability and the nominal coverage probability frequently occurs when approximating a discrete distribution with a continuous one. The construction of binomial confidence intervals is a classic example where coverage probabilities rarely equal nominal levels.
K vitamin Physiology Vitamin_K > Physiology In animals, vitamin K is involved in the carboxylation of certain glutamate residues in proteins to form gamma-carboxyglutamate (Gla) residues. The modified residues are often (but not always) situated within specific protein domains called Gla domains. Gla residues are usually involved in binding calcium, and are essential for the biological activity of all known Gla proteins.17 human proteins with Gla domains have been discovered; they play key roles in the regulation of three physiological processes: Blood coagulation: prothrombin (factor II), factors VII, IX, and X, and proteins C, S, and Z Bone metabolism: osteocalcin, matrix Gla protein (MGP), periostin, and Gla-rich protein. Vascular biology: Matrix Gla protein, growth arrest – specific protein 6 (Gas6) Unknown functions: proline-rich γ-carboxyglutamyl proteins 1 and 2, and transmembrane γ-carboxy glutamyl proteins 3 and 4.
Diving mask Function Half_mask > Function Also, pincushion distortion and lateral chromatic aberration are noticeable. As the diver descends in clean water, the water acts as a colour filter eliminating the red end of the visible spectrum of the sunlight entering the water leaving only the blue end of the spectrum. Depending on the depth and clarity of the water, eventually all sunlight is blocked and the diver has to rely on artificial light sources to see underwater.
Carboxylesterase 1 Function Carboxylesterase_1 > Function Carboxylesterase 1 is a serine esterase and member of a large multigene carboxylesterase family. It is also part of the alpha/beta fold hydrolase family. These enzymes are responsible for the hydrolysis of ester- and amide-bond-containing xenobiotics and drugs such as cocaine and heroin. They also hydrolyze long-chain fatty acid esters and thioesters.
Consensus (computer science) Permissionless consensus protocols Proof_of_elapsed_time > Some consensus protocols > Permissionless consensus protocols Bitcoin uses proof of work, a difficulty adjustment function and a reorganization function to achieve permissionless consensus in its open peer-to-peer network. To extend Bitcoin's blockchain or distributed ledger, miners attempt to solve a cryptographic puzzle, where probability of finding a solution is proportional to the computational effort expended in hashes per second. The node that first solves such a puzzle has their proposed version of the next block of transactions added to the ledger and eventually accepted by all other nodes. As any node in the network can attempt to solve the proof-of-work problem, a Sybil attack is infeasible in principle unless the attacker has over 50% of the computational resources of the network.
Locally flat spacetime Real Minkowski spacetime Minkowski_tensor > History > Real Minkowski spacetime In a further development in his 1908 "Space and Time" lecture, Minkowski gave an alternative formulation of this idea that used a real time coordinate instead of an imaginary one, representing the four variables (x, y, z, t) of space and time in coordinate form in a four dimensional real vector space. Points in this space correspond to events in spacetime. In this space, there is a defined light-cone associated with each point, and events not on the light-cone are classified by their relation to the apex as spacelike or timelike. It is principally this view of spacetime that is current nowadays, although the older view involving imaginary time has also influenced special relativity.
Nuclear weapons yield Calculating yields and controversy Nuclear_yield > Calculating yields and controversy Here S is a dimensionless constant having a value approximately equal to 1, since it is low-order function of the heat capacity ratio or adiabatic index γ = C P C V , {\displaystyle \gamma ={\frac {C_{P}}{C_{V}}},} which is approximately 1 for all conditions. Using the picture of the Trinity test shown here (which had been publicly released by the U.S. government and published in Life magazine), using successive frames of the explosion, Taylor found that R5/t2 is a constant in a given nuclear blast (especially between 0.38 ms, after the shock wave has formed, and 1.93 ms, before significant energy is lost by thermal radiation).
Williams' p + 1 algorithm Example Williams'_p_+_1_algorithm > Example The number 9! is the lowest factorial which is multiple of 810, so the proper factor 811 is found in this step. The factor 139 is not found this time because p−1 = 138 = 2 × 3 × 23 which is not a divisor of 9! As can be seen in these examples we do not know in advance whether the prime that will be found has a smooth p+1 or p−1.
Quartic function Converting to a depressed quartic Quartic_equations > Solution > Solution methods > Converting to a depressed quartic For solving purposes, it is generally better to convert the quartic into a depressed quartic by the following simple change of variable. All formulas are simpler and some methods work only in this case. The roots of the original quartic are easily recovered from that of the depressed quartic by the reverse change of variable.
Behavioral addiction Biomolecular mechanisms Behavioral_addiction > Biomolecular mechanisms Once the behavior is triggered, it is hard to work away from the dopamine reward system. Behaviors like gambling have been linked to the newfound idea of the brain's capacity to anticipate rewards. The reward system can be triggered by early detectors of the behavior, and trigger dopamine neurons to begin stimulating behaviors. But in some cases, it can lead to many issues due to error, or reward-prediction errors. These errors can act as teaching signals to create a complex behavior task over time.
Arterial embolism Pathophysiology Arterial_embolism > Pathophysiology An arterial embolism is caused by one or more emboli getting stuck in an artery and blocking blood flow, causing ischemia, possibly resulting in infarction with tissue death (necrosis). Individuals with arterial thrombosis or embolism often develop collateral circulation to compensate for the loss of arterial flow. However, it takes time for sufficient collateral circulation to develop, making affected areas more vulnerable for sudden occlusion by embolisation than for e.g. gradual occlusion as in atherosclerosis.
AC (complexity) Summary AC_(complexity) In circuit complexity, AC is a complexity class hierarchy. Each class, ACi, consists of the languages recognized by Boolean circuits with depth O ( log i ⁡ n ) {\displaystyle O(\log ^{i}n)} and a polynomial number of unlimited fan-in AND and OR gates. The name "AC" was chosen by analogy to NC, with the "A" in the name standing for "alternating" and referring both to the alternation between the AND and OR gates in the circuits and to alternating Turing machines.The smallest AC class is AC0, consisting of constant-depth unlimited fan-in circuits. The total hierarchy of AC classes is defined as AC = ⋃ i ≥ 0 AC i {\displaystyle {\mbox{AC}}=\bigcup _{i\geq 0}{\mbox{AC}}^{i}}
HIV transmission Prognosis HIV_infection > Prognosis The rate of clinical disease progression varies widely between individuals and has been shown to be affected by a number of factors such as a person's susceptibility and immune function; their access to health care, the presence of co-infections; and the particular strain (or strains) of the virus involved.Tuberculosis co-infection is one of the leading causes of sickness and death in those with HIV/AIDS being present in a third of all HIV-infected people and causing 25% of HIV-related deaths. HIV is also one of the most important risk factors for tuberculosis. Hepatitis C is another very common co-infection where each disease increases the progression of the other.
NAT traversal Techniques NAT_traversal > Techniques Session Traversal Utilities for NAT (STUN) is a standardized set of methods and a network protocol for NAT hole punching. It was designed for UDP but was also extended to TCP. Traversal Using Relays around NAT (TURN) is a relay protocol designed specifically for NAT traversal.
Applications architecture Summary Applications_architecture A migration plan can then be drawn up for systems which are at the end of the software life cycle or which have inherent technological risks, a potential to disrupt the business as a consequence of a technological failure. Applications architecture tries to ensure the suite of applications being used by an organization to create the composite architecture is scalable, reliable, available and manageable. Applications architecture defines how multiple applications are poised to work together. It is different from software architecture, which deals with technical designs of how a system is built.One not only needs to understand and manage the dynamics of the functionalities the composite architecture is implementing but also help formulate the deployment strategy and keep an eye out for technological risks that could jeopardize the growth and/or operations of the organization.
Douglas Hartree Manchester years Douglas_Hartree > Manchester years Results with exchange soon followed. Douglas recognised the importance of configuration interaction that he referred to as "superposition of configurations". The first multiconfiguration Hartree–Fock results were published by father, son, and Bertha Swirles (later Lady Jeffreys) in 1939. At Hartree's suggestion, Bertha Swirles proceeded to derive equations with exchange for atoms using the Dirac equation in 1935. With Hartree's advice, the first relativistic calculations (without exchange) were reported in 1940 by A. O. Williams, a student of R. B. Lindsay.
Essential matrix Derivation and definition Essential_matrix > Derivation and definition Another consequence of the normalized cameras is that their respective coordinate systems are related by means of a translation and rotation. This implies that the two sets of 3D coordinates are related as x ~ ′ = R ( x ~ − t ) {\displaystyle {\tilde {\mathbf {x} }}'=\mathbf {R} \,({\tilde {\mathbf {x} }}-\mathbf {t} )} where R {\displaystyle \mathbf {R} } is a 3 × 3 {\displaystyle 3\times 3} rotation matrix and t {\displaystyle \mathbf {t} } is a 3-dimensional translation vector. The essential matrix is then defined as: where × {\displaystyle _{\times }} is the matrix representation of the cross product with t {\displaystyle \mathbf {t} } .
Internet Architecture Board Responsibilities Internet_Architecture_Board > Responsibilities The IAB's current responsibilities include: Architectural Oversight: The IAB provides oversight of, and occasional commentary on, aspects of the architecture for the network protocols and procedures used by the Internet. Standards Process Oversight and Appeal: The IAB provides oversight of the process used to create Internet Standards. The IAB serves as an appeal board for complaints of improper execution of the standards process, through acting as an appeal body in respect of an Internet Engineering Steering Group (IESG) standards decision. Request for Comments series: The IAB is responsible for editorial management and publication of the Request for Comments (RFC) document series.
ASL name sign Frames ASL_name_sign > Morphology > Frames Frames are a morphological device that may be unique to sign languages (Liddell 2004). They are incomplete sets of the features which make up signs, and they combine with existing signs, absorbing features from them to form a derived sign. It is the frame which specifies the number and nature of segments in the resulting sign, while the basic signs it combines with lose all but one or two of their original features. One, the WEEKLY frame, consists of a simple downward movement.
Rail energy storage Renewable energy Gravitational_potential_energy_storage > Applications > Grid electricity and power stations > Renewable energy If wind or solar generation exceeds the region's hydroelectric capacity, then some additional source of energy is needed. Many renewable energy sources (notably solar and wind) produce variable power.
Anticipatory science Trend analysis Futures_techniques > Trend analysis Short term forecasting seems quite simple; it becomes more complex when the trend is extrapolated further into the future, as the number of dynamic forces that can change direction of the trend increases. This form of simple trend extrapolation helps to direct attention towards the forces, which can change the projected pattern. A more elaborated curve that uses times series analysis can often reveal surprising historical and current data patterns.
Darmstadtium Chemical Darmstadtium > Predicted properties > Chemical In comparison, only platinum is known to show the maximum oxidation state in the group, +6, while the most stable state is +2 for both nickel and palladium. It is further expected that the maximum oxidation states of elements from bohrium (element 107) to darmstadtium (element 110) may be stable in the gas phase but not in aqueous solution. Darmstadtium hexafluoride (DsF6) is predicted to have very similar properties to its lighter homologue platinum hexafluoride (PtF6), having very similar electronic structures and ionization potentials.
Metric symbol International System of Units Metric_symbol > Common metric systems > International System of Units At that time, the metre was redefined in terms of the wavelength of a spectral line of the krypton-86 atom (krypton-86 being a stable isotope of an inert gas that occurs in undetectable or trace amounts naturally), and the standard metre artefact from 1889 was retired. : 16 Today, the International system of units consists of 7 base units and innumerable coherent derived units including 22 with special names. The last new derived unit, the katal for catalytic activity, was added in 1999.
Second order Fresnel lens Design Second_order_Fresnel_lens > Design In some lenses, the curved surfaces are replaced with flat surfaces, with a different angle in each section. Such a lens can be regarded as an array of prisms arranged in a circular fashion with steeper prisms on the edges and a flat or slightly convex center. In the first (and largest) Fresnel lenses, each section was actually a separate prism.
Monte Carlo Simulation Engineering Monte_Carlo_sampling > Applications > Engineering In geostatistics and geometallurgy, Monte Carlo methods underpin the design of mineral processing flowsheets and contribute to quantitative risk analysis. In fluid dynamics, in particular rarefied gas dynamics, where the Boltzmann equation is solved for finite Knudsen number fluid flows using the direct simulation Monte Carlo method in combination with highly efficient computational algorithms. In autonomous robotics, Monte Carlo localization can determine the position of a robot.
Corpuscular theory Polarization Corpuscle_theory_of_light > Polarization At that time polarization was considered proof of the particle theory. Nowadays, polarisation is considered a property of waves and may only manifest in transverse waves. Longitudinal waves may not be polarised.
Long non-coding RNA Imprinting Long_non-coding_RNA > Functions > In epigenetic regulation > Imprinting Transgenic mice with truncated Kcnq1ot fail to silence the adjacent genes, suggesting that Kcnqot1 is crucial to the imprinting of genes on the paternal chromosome. It appears that Kcnqot1 is able to direct the trimethylation of lysine 9 (H3K9me3) and 27 of histone 3 (H3K27me3) to an imprinting centre that overlaps the Kcnqot1 promoter and actually resides within a Kcnq1 sense exon. Similar to HOTAIR (see above), Eed-Ezh2 Polycomb complexes are recruited to the Kcnq1 loci paternal chromosome, possibly by Kcnqot1, where they may mediate gene silencing through repressive histone methylation. A differentially methylated imprinting centre also overlaps the promoter of a long antisense ncRNA Air that is responsible for the silencing of neighbouring genes at the Igf2r locus on the paternal chromosome. The presence of allele-specific histone methylation at the Igf2r locus suggests Air also mediates silencing via chromatin modification.
Prefetch input queue Introduction Prefetch_input_queue > Introduction Pipelining was brought to the forefront of computing architecture design during the 1960s due to the need for faster and more efficient computing. Pipelining is the broader concept and most modern processors load their instructions some clock cycles before they execute them. This is achieved by pre-loading machine code from memory into a prefetch input queue. This behavior only applies to von Neumann computers (that is, not Harvard architecture computers) that can run self-modifying code and have some sort of instruction pipelining.
Knower paradox Formulation Knower_paradox > Formulation The notion of knowledge seems to be governed by the principle that knowledge is factive: (KF): If the sentence ' P ' is known, then P(where we use single quotes to refer to the linguistic expression inside the quotes and where 'is known' is short for 'is known by someone at some time'). It also seems to be governed by the principle that proof yields knowledge: (PK): If the sentence ' P ' has been proved, then ' P ' is knownConsider however the sentence: (K): (K) is not knownAssume for reductio ad absurdum that (K) is known. Then, by (KF), (K) is not known, and so, by reductio ad absurdum, (K) is not known.
Fibrosis Liver Fibrosis > Anatomical location > Liver Bridging fibrosis An advanced stage of liver fibrosis seen in the progressive form of chronic liver diseases. The term “bridging” means ‘the formation of “bridge” (by the band of mature & thick fibrous tissue) obliterating portal area to central vein’, leads to the formation of pseudolobules. Long-term exposure to hepatotoxin (e.g. thioacetamide, carbon tetrachloride, diethylnitrosamine) results in the bridging fibrosis in experimental animal models. Senescence of hepatic stellate cells could prevent progression of liver fibrosis, although this has not been implemented as a therapy, and would carry the risk of hepatic dysfunction.Cirrhosis
Price elasticity of supply Types of price elasticity of supply Price_elasticity_of_supply > Types of price elasticity of supply This can be the case where there is a limited quantity of supply, for example, if there is only 200 of a certain product made and there will never be any more made, there will be no increase or decrease in the quantity of supply.Relatively inelastic supply: This is when the Es formula gives a result between zero and one, meaning that when there is a change in price, the percentage change in supply is lower than the percentage change in price. For example, if a product costs $1 and then increases to $1.10 the increase in price is 10% and therefore the change in supply will be less than 10%.Unit Elastic supply: This is when the Es formula equals to one, meaning that quantity supplied and price change by the same percentage. Using the previous example to show unit elasticity, when there is a 10% increase in price, there will also be a 10% increase in quantity supplied.Relatively elastic supply: This is when the Es formula gives a result above one, meaning that when there is a change in price, the percentage change in supply is higher than the percentage change in price. Using the above example to show an elastic supply, when there is a 10% increase in price there will be more than a 10% increase in supply.Perfectly elastic supply: This is when the Es formula actually gives an infinite result, meaning that the quantity that can be supplied is infinite, however, that is only at a specific price and if the price changes there will be no quantity supplied at all. For example, there may be an infinite supply of product at a price of $1 but if that price changes to $1.10 then the supply becomes zero.
Electric switchboard Components Electric_switchboard > Components In a modern switchboard, the operator is protected from electrical injury by metal-enclosed circuit breakers, switches, and fuses. There may also be instruments and controls for the supply of electricity to the switchboard. For example, a switchboard for a bank of electrical generators, especially frequency would have control of AC power and load sharing, and instruments for frequency, voltage, current, and energy, with perhaps a synchroscope.
Circle–ellipse problem Convert the Circle into an Ellipse Circle–ellipse_problem > Possible solutions > Change the model > Convert the Circle into an Ellipse If Circle.stretchX is called, then Circle changes itself into an Ellipse. For example, in Common Lisp, this can be done via the CHANGE-CLASS method. This may be dangerous, however, if some other function is expecting it to be a Circle. Some languages preclude this type of change, and others impose restrictions on the Ellipse class to be an acceptable replacement for Circle. For languages that allow implicit conversion like C++, this may only be a partial solution solving the problem on call-by-copy, but not on call-by-reference.
Producer–consumer problem Summary Bounded-buffer_problem In computing, the producer-consumer problem (also known as the bounded-buffer problem) is a family of problems described by Edsger W. Dijkstra since 1965. Dijkstra found the solution for the producer-consumer problem as he worked as a consultant for the Electrologica X1 and X8 computers: "The first use of producer-consumer was partly software, partly hardware: The component taking care of the information transport between store and peripheral was called 'a channel' ... Synchronization was controlled by two counting semaphores in what we now know as the producer/consumer arrangement: the one semaphore indicating the length of the queue, was incremented (in a V) by the CPU and decremented (in a P) by the channel, the other one, counting the number of unacknowledged completions, was incremented by the channel and decremented by the CPU. "Dijkstra wrote about the unbounded buffer case: "We consider two processes, which are called the 'producer' and the 'consumer' respectively. The producer is a cyclic process and each time it goes through its cycle it produces a certain portion of information, that has to be processed by the consumer.
Immune network theory The symmetrical immune network theory Immune_network_theory > The symmetrical immune network theory Tabs are able to exert a powerful suppressive effect on the production of IgG antibodies in response to foreign substances (antigens), as was demonstrated rigorously by Takemori and Tada. Hoffmann and Gorczynski have reproduced the Takemori and Tada experiment, confirming the existence of specific T cell factors. In the symmetrical network theory tabs are able to block V regions and also to have a stimulatory role when bound to a tab receptor on A cells.
Eötvös rule History Eötvös_rule > History John Lennard-Jones and Corner published (1940) a derivation of the equation by means of statistical mechanics. In 1945 E. A. Guggenheim gave a further improved variant of the equation. == References ==
Discovery and development of beta-blockers History Discovery_and_development_of_beta-blockers > Development > History The β-blockers are an immensely important class of drugs due to their high prevalence of use. The discovery of β-blockers reaches back to more than 100 years ago, when early investigators came up with the idea that catecholamines were binding selectively to receptor-like structures and that this was the cause of their pharmacological actions. In 1948, Raymond P. Ahlquist published a seminal paper concluding his findings, that there were two distinct receptors for catecholamine drugs, and they caused different responses in the heart muscle. He labeled them α-and β-adrenoceptors.
Oxo process Steric effects Oxo_process > Mechanism > Steric effects Markovnikov's rule addition of the cobalt hydride to primary alkenes is disfavored by steric hindrance between the cobalt centre and the secondary alkyl ligand. Bulky ligands exacerbate this steric hindrance. Hence, the mixed carbonyl/phosphine complexes offer a greater selectivity for anti-Markovnikov addition, thus favoring straight chain products (n-) aldehydes. Modern catalysts rely increasingly on chelating ligands, especially diphosphites.
Soft heap Summary Soft_heap In computer science, a soft heap is a variant on the simple heap data structure that has constant amortized time complexity for 5 types of operations. This is achieved by carefully "corrupting" (increasing) the keys of at most a constant number of values in the heap.
The Hallmarks of Cancer List of hallmarks The_Hallmarks_of_Cancer > List of hallmarks If they can't be repaired, they commit programmed cell death (apoptosis). They can only divide a limited number of times. They are part of a tissue structure, and remain where they belong.
Refractometer Automatic Refractometer > Automatic Automatic refractometers automatically measure the refractive index of a sample. The automatic measurement of the refractive index of the sample is based on the determination of the critical angle of total reflection. A light source, usually a long-life LED, is focused onto a prism surface via a lens system. An interference filter guarantees the specified wavelength.
List of mathematical functions Miscellaneous functions List_of_mathematical_functions > Special functions > Miscellaneous functions Kronecker delta function: is a function of two variables, usually integers, which is 1 if they are equal, and 0 otherwise. Minkowski's question mark function: Derivatives vanish on the rationals. Weierstrass function: is an example of continuous function that is nowhere differentiable
Gal operon Mechanism Gal_operon > Mechanism The unlinked galR gene encodes the repressor for this system. A tetrameric GalR repressor binds to 2 operators, one located at +55 and one located at -60 relative to the PG1 start site. Looping of the DNA blocks the access of RNA polymerase to promoters and/or inhibits formation of the open complex. This looping requires the presence of the histone-like protein, HU to facilitate the formation of the structure and allow for proper repression.
History of tuberculosis Books History_of_tuberculosis > References > Books Twenty-First Century Books. ISBN 978-0761316244. Zysk, Kenneth G.
Control Engineering History Control_engineer > History Automatic control systems were first developed over two thousand years ago. The first feedback control device on record is thought to be the ancient Ktesibios's water clock in Alexandria, Egypt, around the third century BCE. It kept time by regulating the water level in a vessel and, therefore, the water flow from that vessel. This certainly was a successful device as water clocks of similar design were still being made in Baghdad when the Mongols captured the city in 1258 CE.
Oxidation catalysis Challenges Catalytic_oxidation > Challenges The foremost challenge in catalytic oxidation is the conversion of methane to methanol. Most methane is stranded, i.e. not located near metropolitan areas. Consequently, it is flared (converted to carbon dioxide).
Auerbach's plexus Role in CNS disorders Myenteric_plexus > Clinical significance > Role in CNS disorders Because the ENS is known as the "brain of the gut", due to its similarities with the CNS, researchers have been using colonic biopsies of Parkinson's patients to help better understand and manage Parkinson's disease. PD patients are known to experience severe constipation due to GI tract dysfunction years before the onset of motor movement complications, which characterises Parkinson's disease.
DREF friction spinning Summary DREF_friction_spinning Friction spinning or DREF spinning is a textile technology that is suitable for spinning coarse counts of yarns and technical core-wrapped yarns. DREF yarns are bulky with low tensile strength, making them suitable for blankets and mop yarns. They can be spun from asbestos, carbon fibres and are capable of being made into filters for water systems. Yarns such as Rayon and Kevlar can be spun using this method. The technology was developed around 1975 by Dr. Ernst Fehrer.
Cas di torto House layout Cas_di_torto > Construction and material > House layout The water was sourced from small lakes called tanki's, which collected rainwater. The kitchen was equipped with a fireplace located against the western wall of the extension. This fireplace featured a raised fire pit, about 85 centimetres (2.79 ft) above the floor, completely surrounded by walls.
Histogram of oriented displacements Summary Histogram_of_oriented_displacements Histogram of Oriented Displacements (HOD) is a 2D trajectory descriptor. The trajectory is described using a histogram of the directions between each two consecutive points. Given a trajectory T = {P1, P2, P3, ..., Pn}, where Pt is the 2D position at time t. For each pair of positions Pt and Pt+1, calculate the direction angle θ(t, t+1). Value of θ is between 0 and 360.
M1 protein Summary M1_protein The M1 protein is a matrix protein of the influenza virus. It forms a coat inside the viral envelope. This is a bifunctional membrane/RNA-binding protein that mediates the encapsidation of nucleoprotein cores into the membrane envelope.
Linnett Double-Quartet Theory Example: molecular oxygen Linnett_Double-Quartet_Theory > Examples of the application of the theory > Example: molecular oxygen Linnett postulated that this electronic arrangement reduces the magnitude of the inter-electronic repulsions in comparison with the case where the two spin sets have six electrons each. This arrangement results in a bond order of 2 and an excess of one electron spin, giving rise to the molecule's paramagnetism: both observations are in agreement with molecular orbital theory treatments of the molecule. In effect, the LDQ structure is equivalent to the combination of a two-centre one-electron bond (purple spin set) and a two-centre three-electron bond (green spin set).
Fluid and crystallized intelligence Matrix Reasoning Fluid_and_crystallized_intelligence > Measurement of fluid intelligence > Wechsler Intelligence Scales for Children, Fourth Edition > Matrix Reasoning Matrix Reasoning also assesses this ability as well as the ability to start with stated rules, premises, or conditions and to engage in one or more steps to reach a solution to a novel problem (deduction). In the Matrix Reasoning test, children have presented with a series or sequence of pictures with one picture missing. Their task requires the child to choose the picture that fits the series or sequence from an array of five options. Since Matrix Reasoning and Picture Concepts involve the use of visual stimuli and do not require expressive language, they have been considered to be non-verbal tests of gf.
Automation Significant applications Automatic_control > History > Significant applications Before automation, many chemicals were made in batches. In 1930, with the widespread use of instruments and the emerging use of controllers, the founder of Dow Chemical Co. was advocating continuous production.Self-acting machine tools that displaced hand dexterity so they could be operated by boys and unskilled laborers were developed by James Nasmyth in the 1840s.
Generalized Bernoulli number Early history Bernoulli_Numbers > History > Early history In the West Thomas Harriot (1560–1621) of England, Johann Faulhaber (1580–1635) of Germany, Pierre de Fermat (1601–1665) and fellow French mathematician Blaise Pascal (1623–1662) all played important roles. Thomas Harriot seems to have been the first to derive and write formulas for sums of powers using symbolic notation, but even he calculated only up to the sum of the fourth powers. Johann Faulhaber gave formulas for sums of powers up to the 17th power in his 1631 Academia Algebrae, far higher than anyone before him, but he did not give a general formula.
Modern chemistry Energy Modern_chemistry > Modern principles > Energy Thus, because vibrational and rotational energy levels are more closely spaced than electronic energy levels, heat is more easily transferred between substances relative to light or other forms of electronic energy. For example, ultraviolet electromagnetic radiation is not transferred with as much efficacy from one substance to another as thermal or electrical energy.
Project Mathematics! The Theorem of Pythagoras Project_Mathematics! > Video module descriptions > The Theorem of Pythagoras A clay tablet shows that the Babylonians knew of Pythagorean triples 1200 years before Pythagoras, but nobody knows if they knew the more-general Pythagorean theorem. The Chinese proof uses four similar triangles to prove the theorem. Today, we know of the Pythagorean theorem because of Euclid's Elements, a set of 13 books on mathematics—from around 300 BCE—and the knowledge it contained has been used for more than 2000 years.
Spectral sequences The spectral sequence of a double complex Spectral_sequence > Constructions of spectral sequences > The spectral sequence of a double complex {\displaystyle {}^{I}E_{p,q}^{2}=H_{p}^{I}(H_{q}^{II}(C_{\bullet ,\bullet })).} Using the other filtration gives us a different spectral sequence with a similar E2 term: I I E p , q 2 = H q I I ( H p I ( C ∙ , ∙ ) ) . {\displaystyle {}^{II}E_{p,q}^{2}=H_{q}^{II}(H_{p}^{I}(C_{\bullet ,\bullet })).} What remains is to find a relationship between these two spectral sequences. It will turn out that as r increases, the two sequences will become similar enough to allow useful comparisons.
Dominant function Dominant chords Dominant_function > Dominant chords These chords may also appear as seventh chords: typically as a dominant seventh chord, but occasionally in minor as a minor seventh chord v7 with passing function: As defined by the 19th century musicologist Joseph Fétis, the dominante was a seventh chord over the first note of a descending perfect fifth in the basse fondamentale or root progression, the common practice period dominant seventh he named the dominante tonique.Dominant chords are important to cadential progressions. In the strongest cadence, the authentic cadence (example shown below), the dominant chord is followed by the tonic chord. A cadence that ends with a dominant chord is called a half cadence or an "imperfect cadence".
Positive definite kernel History Positive_definite_kernel > History He therefore defined a continuous real symmetric kernel K ( s , t ) {\displaystyle K(s,t)} to be of positive type (i.e. positive-definite) if J ( x ) ≥ 0 {\displaystyle J(x)\geq 0} for all real continuous functions x {\displaystyle x} on {\displaystyle } , and he proved that (1.1) is a necessary and sufficient condition for a kernel to be of positive type. Mercer then proved that for any continuous p.d. kernel the expansion holds absolutely and uniformly.
Kinetic temperature Bibliography of cited references Kinetic_temperature > Notes and references > Bibliography of cited references Temperature, Academic Press, London, ISBN 0-12-569680-9. Schooley, J.F. (1986).
Social inclusion Individual exclusion Social_inclusion > Individual exclusion Cantor also discusses employer concern about the excessively high cost of accommodating people with disabilities. The marginalization of individuals with disabilities is prevalent today, despite the legislation intended to prevent it in most western countries, and the academic achievements, skills and training of many disabled people.There are also exclusions of sexual minorities because of their sexual orientation, gender identity, and/or sexual characteristics.
Lung arteries Summary Lung_arteries A number of occupational lung diseases can be caused by substances such as coal dust, asbestos fibres, and crystalline silica dust. Diseases such as bronchitis can also affect the respiratory tract. Medical terms related to the lung often begin with pulmo-, from the Latin pulmonarius (of the lungs) as in pulmonology, or with pneumo- (from Greek πνεύμων "lung") as in pneumonia.
Classical genetics Overview Classical_genetics > Overview Genes are a fundamental part of DNA that is aligned linearly on a eukaryotic chromosome. Chemical information that is transported and encoded by each gene is referred to as a trait. Many organisms possess two genes for each individual trait that is present within that particular individual.
Resistors in series Carbon pile Resistors_in_series > Fixed resistors > Carbon pile A carbon pile resistor is made of a stack of carbon disks compressed between two metal contact plates. Adjusting the clamping pressure changes the resistance between the plates. These resistors are used when an adjustable load is required, such as in testing automotive batteries or radio transmitters. A carbon pile resistor can also be used as a speed control for small motors in household appliances (sewing machines, hand-held mixers) with ratings up to a few hundred watts. A carbon pile resistor can be incorporated in automatic voltage regulators for generators, where the carbon pile controls the field current to maintain relatively constant voltage. This principle is also applied in the carbon microphone.
RNA World Alternative hypotheses Peptide-RNA_world > Alternative hypotheses Sugar molecules, including ribose, have been found in meteorites. Panspermia does not invalidate the concept of an RNA world, but posits that this world or its precursors originated not on Earth but rather another, probably older, planet. The relative chemical complexity of the nucleotide and the unlikelihood of it spontaneously arising, along with the limited number of combinations possible among four base forms, as well as the need for RNA polymers of some length before seeing enzymatic activity, have led some to reject the RNA world hypothesis in favor of a metabolism-first hypothesis, where the chemistry underlying cellular function arose first, along with the ability to replicate and facilitate this metabolism.
Regular Expression Expressive power and compactness Regular_Expressions > Formal language theory > Expressive power and compactness For instance, determining the validity of a given ISBN requires computing the modulus of the integer base 11, and can be easily implemented with an 11-state DFA. However, a regular expression to answer the same problem of divisibility by 11 is at least multiple megabytes in length.Given a regular expression, Thompson's construction algorithm computes an equivalent nondeterministic finite automaton. A conversion in the opposite direction is achieved by Kleene's algorithm. Finally, it is worth noting that many real-world "regular expression" engines implement features that cannot be described by the regular expressions in the sense of formal language theory; rather, they implement regexes. See below for more on this.
Outgroup (cladistics) History Outgroup_(cladistics) > History Although the concept of outgroups has been in use from the earliest days of cladistics, the term "outgroup" is thought to have been coined in the early 1970s at the American Museum of Natural History. Prior to the advent of the term, various other terms were used by evolutionary biologists, including "exgroup", "related group", and "outside groups".
Recursive InterNetwork Architecture Naming, addressing, routing, mobility and multihoming Recursive_InterNetwork_Architecture > Overview > Naming, addressing, routing, mobility and multihoming A node can be connected to a pair of attachment points and should be able to move between them without losing its identity in the network. A directory maps an application name to a node address, and routes are sequences of node addresses and attachment points. These points are illustrated in Figure 6.
Electrochemical reduction Spontaneity of redox reaction Electrochemical_reactions > Spontaneity of redox reaction It can be used to calculate the maximum possible electrical energy that could be obtained from a chemical reaction. This energy is referred to as electrical work and is expressed by the following equation: W m a x = W e l e c t r i c a l = − n e F E c e l l {\displaystyle W_{\mathrm {max} }=W_{\mathrm {electrical} }=-n_{e}FE_{\mathrm {cell} }} ,where work is defined as positive when it increases the energy of the system. Since the free energy is the maximum amount of work that can be extracted from a system, one can write: Δ G = − n e F E c e l l {\displaystyle \Delta G=-n_{e}FE_{\mathrm {cell} }} A positive cell potential gives a negative change in Gibbs free energy.
Fair river sharing Cooperation when countries are non-satiable Fair_river_sharing > Stable monetary transfers > Cooperation when countries are non-satiable Moreover, the aspiration level of each coalition of countries is the highest utility-level it could attain in the absence of the other countries. This implies an upper bound on the utility of each coalition, called the aspiration upper bound. There is at most one welfare-distribution that satisfies both the core-lower-bound and the aspiration-upper-bound: it is the downstream incremental distribution.
Symbiodinium Intracellular symbionts Symbiodinium > Intracellular symbionts This membrane probably undergoes some modification to its protein content, which functions to limit or prevent phago-lysosome fusion. The vacuole structure containing the symbiont is therefore termed the symbiosome. A single symbiont cell occupies each symbiosome. It is unclear how this membrane expands to accommodate a dividing symbiont cell. Under normal conditions, symbiont and host cells exchange organic and inorganic molecules that enable the growth and proliferation of both partners.
Catoptric tessellation Symmetry Catoptric_tessellation > Symmetry These four symmetry groups are labeled as:
Bora (Australian) Bora grounds and mythology Bora_(Australian) > Bora grounds and mythology The former was a more public space while the latter was sacred, and restricted to male participants who were either the instructing male elders or the initiants.In south-east Australia, the Bora is often associated with the creator-spirit Baiame. In the Sydney region, large earth mounds were made, shaped as long bands or simple circles. Sometimes the boys would have to pass along a path marked on the ground representing the transition from childhood to manhood, and this path might be marked by a stone arrangement or by spirit footprints (mundowa), cut into the rock.
Constant speed propeller Constant-speed propellers Propeller_governor > Mechanisms > Constant-speed propellers A constant-speed propeller is a variable-pitch propeller that automatically changes its blade pitch in order to maintain a chosen rotational speed, regardless of the operational conditions of the aircraft. This is achieved by use of a constant-speed unit (CSU) or propeller governor, which automatically changes the propeller's blade pitch. Most engines produce their maximum power in a narrow speed band. The CSU allows the engine to operate in its most economical range of rotational speeds, regardless of whether the aircraft is taking off or cruising.
Glutamate receptor Parkinson's disease (Parkinsonism) Glutamate_receptor > Conditions with demonstrated associations to glutamate receptors > Parkinson's disease (Parkinsonism) Late onset neurological disorders, such as Parkinson's disease, may be partially due to glutamate binding NMDA and AMPA glutamate receptors. In vitro spinal cord cultures with glutamate transport inhibitors led to degeneration of motor neurons, which was counteracted by some AMPA receptor antagonists such as GYKI 52466. Research also suggests that the metabotropic glutamate receptor mGlu4 is directly involved in movement disorders associated with the basal ganglia through selectively modulating glutamate in the striatum.
Undecidable problem Examples of undecidable problems Undecidable_problem > Examples of undecidable problems Undecidable problems can be related to different topics, such as logic, abstract machines or topology. Since there are uncountably many undecidable problems, any list, even one of infinite length, is necessarily incomplete.
139 (number) In mathematics 139_(number) > In mathematics 139 is the 34th prime number. It is a twin prime with 137. Because 141 is a semiprime, 139 is a Chen prime. 139 is the smallest prime before a prime gap of length 10.This number is the sum of five consecutive prime numbers (19 + 23 + 29 + 31 + 37).
HMG CoA reductase Hormones HMG-CoA_reductase > Inhibitors > Hormones HMG-CoA reductase is active when blood glucose is high. The basic functions of insulin and glucagon are to maintain glucose homeostasis. Thus, in controlling blood sugar levels, they indirectly affect the activity of HMG-CoA reductase, but a decrease in activity of the enzyme is caused by AMP-activated protein kinase, which responds to an increase in AMP concentration, and also to leptin.
Zassenhaus lemma Resources Zassenhaus_lemma > Resources ), Springer-Verlag, pp. 20–21, ISBN 978-0-387-95385-4.
Open pond Photobioreactors Open_pond > Growing, harvesting, and processing algae > Methods > Photobioreactors The grower provides sterilized water, nutrients, air, and carbon dioxide at the correct rates. This allows the reactor to operate for long periods. An advantage is that algae that grows in the "log phase" is generally of higher nutrient content than old "senescent" algae.
Deep linguistic processing Summary Deep_linguistic_processing The knowledge-intensive approach of deep linguistic processing requires considerable computational power, and has in the past sometimes been judged as being intractable. However, research in the early 2000s had made considerable advancement in efficiency of deep processing. Today, efficiency is no longer a major problem for applications using deep linguistic processing.
Steel arch bridge Construction sequence Steel_arch_bridge > Construction sequence When the arches are almost complete a jacking bridge is placed over or beneath the gap to force the arches apart, whence the final section is constructed in place or lifted into position. In some cases, this type of arch has been created by constructing cantilevers from each side, with the shoreside ends bolted securely down into heavy piers. The incomplete channel ends are then constructed toward each other and either filled by construction or by lifting a prefabricated center section. This type of construction was used in the Sydney Harbour Bridge illustrated above, with the supporting cables to the higher side of the arches removed after completion.
Optic nerve Disease Optic_nerve > Clinical significance > Disease Optic nerve hypoplasia is the underdevelopment of the optic nerve resulting in little to no vision in the affected eye. Tumors, especially those of the pituitary gland, can put pressure on the optic nerve causing various forms of visual loss. Similarly, cerebral aneurysms, a swelling of blood vessel(s), can also affect the nerve.
Semantic compaction Usage and Learnability Semantic_compaction > Usage and Learnability A follow-up study found that icon prediction, in which the options available for selection are highlighted, did not help children to locate vocabulary more accurately, but there was some evidence that the use of icon prediction may facilitate generalization of semantic compaction strategies to new vocabulary items.On the other hand, there is research that indicates that intensive teaching (including practice outside of therapy sessions) can improve young children's ability to use semantic compaction accurately. A case study of a 3-year-old girl with cerebral palsy revealed that intensive, systematic training involving the client, family members, therapists, and educational teams can make it possible to achieve marked progress in early language skills while learning and using a Minspeak device. Learnability of Minspeak systems may heavily depend on the quality of its teaching and how often it is used with a specific child.
Spin move Revolution Spin_(geometry) > Astronomy > Revolution While revolution is often used as a synonym for rotation, in many fields, particularly astronomy and related fields, revolution, often referred to as orbital revolution for clarity, is used when one body moves around another while rotation is used to mean the movement around an axis. Moons revolve around their planet, planets revolve about their star (such as the Earth around the Sun); and stars slowly revolve about their galaxial center. The motion of the components of galaxies is complex, but it usually includes a rotation component.
Problem structuring methods Types of situations that call for PSMs Problem_structuring_methods > Types of situations that call for PSMs In discussions of problem structuring methods, it is common to distinguish between two different types of situations that could be considered to be problems. Rittel and Webber's distinction between tame problems and wicked problems (Rittel & Webber 1973) is a well known example of such types. The following table lists similar (but not exactly equivalent) distinctions made by a number of thinkers between two types of "problem" situations, which can be seen as a continuum between a left and right extreme: Tame problems (or puzzles or technical challenges) have relatively precise, straightforward formulations that are often amenable to solution with some predetermined technical fix or algorithm.
Whole-cell vaccine Whole-cell Pneumococcal vaccine Whole-cell_vaccine > Whole-cell Pneumococcal vaccine The whole-cell pneumococcal vaccine consisted of inactive Streptococcus pneumonia RM200 cells and was the first whole-cell vaccine used against S.pneumoniae. In 2012, Phase-I studies were conducted by combining the whole-cell vaccine with alum. 1 out of 42 experienced adverse reactions which were not related to vaccination. The mild reactions experienced were similar to the control groups. Immunoglobulin G responses to the whole-cell vaccine was determined by pan proteome microassay and found that the whole-cell pneumococcal vaccine induced an increase in IgG response in a naturally immunogenic protein expressed by RM200 and also caused a reaction to PclA, PspC and ZmpB protein variants.
Malware analysis Stages Malware_analysis > Stages Examining malicious software involves several stages, including, but not limited to the following: Manual Code Reversing Interactive Behavior Analysis Static Properties Analysis Fully-Automated Analysis == References ==
Drift current Overview Drift_current > Overview Drift current is the electric current caused by particles getting pulled by an electric field. The term is most commonly used in the context of electrons and holes in semiconductors, although the same concept also applies to metals, electrolytes, and so on. Drift current is caused by the electric force: Charged particles get pushed by an electric field. Electrons, being negatively charged, get pushed in the opposite direction to the electric field, while holes get pushed in the same direction as the electric field, but the resulting conventional current points in the same direction as the electric field in both cases.
C1 and P1 Summary C1_and_P1 The C1 and P1 (also called the P100) are two human scalp-recorded event-related brain potential (event-related potential (ERP)) components, collected by means of a technique called electroencephalography (EEG). The C1 is named so because it was the first component in a series of components found to respond to visual stimuli when it was first discovered. It can be a negative-going component (when using a mastoid reference point) or a positive going component with its peak normally observed in the 65–90 ms range post-stimulus onset. The P1 is called the P1 because it is the first positive-going component (when also using a mastoid reference point) and its peak is normally observed in around 100 ms.
Back titration Miscellaneous Volumetric_analysis > Particular uses > Miscellaneous Karl Fischer titration: A potentiometric method to analyze trace amounts of water in a substance. A sample is dissolved in methanol, and titrated with Karl Fischer reagent(consists of iodine, sulfur dioxide, a base and a solvent, such as alcohol, maybe EtOH). The reagent contains iodine, which reacts proportionally with water. Thus, the water content can be determined by monitoring the electric potential of excess iodine.

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