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From these eggs hatch zoeae, the first larval stage of crustaceans. They drift towards brackish waters where they go through several larval stages before metamorphosing into postlarvae, at which stage they are about 8 mm long and have all the characteristics of adults. This metamorphosis usually takes place about 32 to... | Freshwater prawn farming | Wikipedia | 431 | 2167409 | https://en.wikipedia.org/wiki/Freshwater%20prawn%20farming | Technology | Aquaculture | null |
The technologies used in freshwater prawn farming are basically the same as in marine shrimp farming. Hatcheries produce postlarvae, which then are grown and acclimated in nurseries before being transferred into growout ponds, where the prawns are then fed and grown until they reach marketable size. Harvesting is done ... | Freshwater prawn farming | Wikipedia | 510 | 2167409 | https://en.wikipedia.org/wiki/Freshwater%20prawn%20farming | Technology | Aquaculture | null |
The global annual production of freshwater prawns in 2003 was about 280,000 tonnes, of which China produced some 180,000 tonnes, followed by India and Thailand with some 35,000 tonnes each. Other major producer countries are Taiwan, Bangladesh, and Vietnam. In the United States, only a few hundred small farms for M. ro... | Freshwater prawn farming | Wikipedia | 76 | 2167409 | https://en.wikipedia.org/wiki/Freshwater%20prawn%20farming | Technology | Aquaculture | null |
In fluid dynamics, the reyn is a British unit of dynamic viscosity,
named in honour of Osbourne Reynolds, for whom the Reynolds number is also named.
Conversions
By definition,
1 reyn = 1 lbf s in−2.
It follows that the relation between the reyn and the poise is approximately
1 reyn = 6.89476 × 104 P.
In SI units, vi... | Reyn | Wikipedia | 120 | 2168763 | https://en.wikipedia.org/wiki/Reyn | Physical sciences | Viscosity | Basics and measurement |
In biology, cell signaling (cell signalling in British English) is the process by which a cell interacts with itself, other cells, and the environment. Cell signaling is a fundamental property of all cellular life in prokaryotes and eukaryotes.
Typically, the signaling process involves three components: the signal, th... | Cell signaling | Wikipedia | 426 | 4109042 | https://en.wikipedia.org/wiki/Cell%20signaling | Biology and health sciences | Cell processes | null |
Receptors are complex proteins or tightly bound multimer of proteins, located in the plasma membrane or within the interior of the cell such as in the cytoplasm, organelles, and nucleus. Receptors have the ability to detect a signal either by binding to a specific chemical or by undergoing a conformational change when ... | Cell signaling | Wikipedia | 376 | 4109042 | https://en.wikipedia.org/wiki/Cell%20signaling | Biology and health sciences | Cell processes | null |
The effector component of the signaling pathway begins with signal transduction. In this process, the signal, by interacting with the receptor, starts a series of molecular events within the cell leading to the final effect of the signaling process. Typically the final effect consists in the activation of an ion channe... | Cell signaling | Wikipedia | 424 | 4109042 | https://en.wikipedia.org/wiki/Cell%20signaling | Biology and health sciences | Cell processes | null |
In plants and animals, signaling between cells occurs either through release into the extracellular space, divided in paracrine signaling (over short distances) and endocrine signaling (over long distances), or by direct contact, known as juxtacrine signaling such as notch signaling. Autocrine signaling is a special ca... | Cell signaling | Wikipedia | 428 | 4109042 | https://en.wikipedia.org/wiki/Cell%20signaling | Biology and health sciences | Cell processes | null |
Exocytosis is the process by which a cell transports molecules such as neurotransmitters and proteins out of the cell. As an active transport mechanism, exocytosis requires the use of energy to transport material. Exocytosis and its counterpart, endocytosis, the process that brings substances into the cell, are used by... | Cell signaling | Wikipedia | 500 | 4109042 | https://en.wikipedia.org/wiki/Cell%20signaling | Biology and health sciences | Cell processes | null |
Juxtacrine
Juxtacrine signaling is a type of cell–cell or cell–extracellular matrix signaling in multicellular organisms that requires close contact. There are three types:
A membrane ligand (protein, oligosaccharide, lipid) and a membrane protein of two adjacent cells interact.
A communicating junction links the in... | Cell signaling | Wikipedia | 469 | 4109042 | https://en.wikipedia.org/wiki/Cell%20signaling | Biology and health sciences | Cell processes | null |
Although paracrine signaling elicits a diverse array of responses in the induced cells, most paracrine factors utilize a relatively streamlined set of receptors and pathways. In fact, different organs in the body - even between different species - are known to utilize a similar sets of paracrine factors in differential... | Cell signaling | Wikipedia | 404 | 4109042 | https://en.wikipedia.org/wiki/Cell%20signaling | Biology and health sciences | Cell processes | null |
Signaling molecules interact with a target cell as a ligand to cell surface receptors, and/or by entering into the cell through its membrane or endocytosis for intracrine signaling. This generally results in the activation of second messengers, leading to various physiological effects. In many mammals, early embryo cel... | Cell signaling | Wikipedia | 442 | 4109042 | https://en.wikipedia.org/wiki/Cell%20signaling | Biology and health sciences | Cell processes | null |
These receptor proteins are typically composed of at least two different domains: a transmembrane domain which includes the ion pore, and an extracellular domain which includes the ligand binding location (an allosteric binding site). This modularity has enabled a 'divide and conquer' approach to finding the structure ... | Cell signaling | Wikipedia | 424 | 4109042 | https://en.wikipedia.org/wiki/Cell%20signaling | Biology and health sciences | Cell processes | null |
There are two principal signal transduction pathways involving the G protein-coupled receptors: cAMP signal pathway and phosphatidylinositol signal pathway. When a ligand binds to the GPCR it causes a conformational change in the GPCR, which allows it to act as a guanine nucleotide exchange factor (GEF). The GPCR can t... | Cell signaling | Wikipedia | 377 | 4109042 | https://en.wikipedia.org/wiki/Cell%20signaling | Biology and health sciences | Cell processes | null |
They have two important domains, an extra-cellular ligand binding domain and an intracellular domain, which has a catalytic function; and a single transmembrane helix. The signaling molecule binds to the receptor on the outside of the cell and causes a conformational change on the catalytic function located on the rec... | Cell signaling | Wikipedia | 511 | 4109042 | https://en.wikipedia.org/wiki/Cell%20signaling | Biology and health sciences | Cell processes | null |
Reducing the sensitivity of the receptor is a result of receptors being occupied for a long time. This results in a receptor adaptation in which the receptor no longer responds to the signaling molecule. Many receptors have the ability to change in response to ligand concentration.
Signal transduction pathways
When b... | Cell signaling | Wikipedia | 406 | 4109042 | https://en.wikipedia.org/wiki/Cell%20signaling | Biology and health sciences | Cell processes | null |
A more complex signal transduction pathway is the MAPK/ERK pathway, which involves changes of protein–protein interactions inside the cell, induced by an external signal. Many growth factors bind to receptors at the cell surface and stimulate cells to progress through the cell cycle and divide. Several of these recepto... | Cell signaling | Wikipedia | 375 | 4109042 | https://en.wikipedia.org/wiki/Cell%20signaling | Biology and health sciences | Cell processes | null |
A specific cellular response is the result of the transduced signal in the final stage of cell signaling. This response can essentially be any cellular activity that is present in a body. It can spur the rearrangement of the cytoskeleton, or even as catalysis by an enzyme. These three steps of cell signaling all ensure... | Cell signaling | Wikipedia | 326 | 4109042 | https://en.wikipedia.org/wiki/Cell%20signaling | Biology and health sciences | Cell processes | null |
Notch is a cell surface protein that functions as a receptor. Animals have a small set of genes that code for signaling proteins that interact specifically with Notch receptors and stimulate a response in cells that express Notch on their surface. Molecules that activate (or, in some cases, inhibit) receptors can be cl... | Cell signaling | Wikipedia | 451 | 4109042 | https://en.wikipedia.org/wiki/Cell%20signaling | Biology and health sciences | Cell processes | null |
The body louse (Pediculus humanus humanus, also known as Pediculus humanus corporis) or the cootie is a hematophagic ectoparasite louse that infests humans. It is one of three lice which infest humans, the other two being the head louse, and the crab louse or pubic louse.
Body lice may lay eggs on the host hairs and ... | Body louse | Wikipedia | 427 | 5482408 | https://en.wikipedia.org/wiki/Body%20louse | Biology and health sciences | Insects and other hexapods | null |
Eggs (also called nits, see head louse nits) are attached to the clothes or hairs by the female louse, using a secretion of the accessory glands that holds the egg in place until it hatches, while the nits (empty egg shells) may remain for months on the clothing. They are oval and usually yellow to white in color and a... | Body louse | Wikipedia | 511 | 5482408 | https://en.wikipedia.org/wiki/Body%20louse | Biology and health sciences | Insects and other hexapods | null |
Treatment
In principle, body louse infestations can be controlled by periodically changing clothes and bedding. Thereafter, clothes, towels, and bedding should be washed in hot water (at least ) and dried using a hot cycle. The itching can be treated with topical and systemic corticosteroids and antihistamines. In cas... | Body louse | Wikipedia | 283 | 5482408 | https://en.wikipedia.org/wiki/Body%20louse | Biology and health sciences | Insects and other hexapods | null |
A planthopper is any insect in the infraorder Fulgoromorpha, in the suborder Auchenorrhyncha, a group exceeding 12,500 described species worldwide. The name comes from their remarkable resemblance to leaves and other plants of their environment and that they often "hop" for quick transportation in a similar way to that... | Planthopper | Wikipedia | 476 | 5485503 | https://en.wikipedia.org/wiki/Planthopper | Biology and health sciences | Hemiptera (true bugs) | Animals |
Classification
The infraorder contains two superfamilies, Fulgoroidea and Delphacoidea. As mentioned under Auchenorrhyncha, some authors use the name Archaeorrhyncha as a replacement for the Fulgoromorpha.
Superfamily Fulgoroidea
Acanaloniidae
Achilidae
Achilixiidae
Caliscelidae
Derbidae
Dictyopharidae
Eurybra... | Planthopper | Wikipedia | 443 | 5485503 | https://en.wikipedia.org/wiki/Planthopper | Biology and health sciences | Hemiptera (true bugs) | Animals |
Aluminium carbide, chemical formula Al4C3, is a carbide of aluminium. It has the appearance of pale yellow to brown crystals. It is stable up to 1400 °C. It decomposes in water with the production of methane.
Structure
Aluminium carbide has an unusual crystal structure that consists of alternating layers of Al2C and A... | Aluminium carbide | Wikipedia | 392 | 5489512 | https://en.wikipedia.org/wiki/Aluminium%20carbide | Physical sciences | Carbide salts | Chemistry |
Silicon carbide also reacts with aluminium to yield Al4C3. This conversion limits the mechanical applications of SiC, because Al4C3 is more brittle than SiC.
4 Al + 3 SiC → Al4C3 + 3 Si
In aluminium-matrix composites reinforced with silicon carbide, the chemical reactions between silicon carbide and molten aluminium... | Aluminium carbide | Wikipedia | 376 | 5489512 | https://en.wikipedia.org/wiki/Aluminium%20carbide | Physical sciences | Carbide salts | Chemistry |
A reflex hammer is a medical instrument used by practitioners to test deep tendon reflexes, the best known possibly being the patellar reflex. Testing for reflexes is an important part of the neurological physical examination in order to detect abnormalities in the central or peripheral nervous system.
Reflex hammers... | Reflex hammer | Wikipedia | 124 | 5489731 | https://en.wikipedia.org/wiki/Reflex%20hammer | Technology | Devices | null |
Starting in the late 19th century, several models of specific reflex hammers were created:
The Taylor or tomahawk reflex hammer was designed by John Madison Taylor in 1888 and is the most well known reflex hammer in the USA. It consists of a triangular rubber component which is attached to a flat metallic handle. The ... | Reflex hammer | Wikipedia | 508 | 5489731 | https://en.wikipedia.org/wiki/Reflex%20hammer | Technology | Devices | null |
The Taylor hammer is usually held at the end by the physician, and the entire device is swung in an arc-like motion onto the tendon in question. The Queen Square and Babinski hammers are usually held perpendicular to the tendon in question, and are passively swung with gravity assistance onto the tendon.
The Jendrass... | Reflex hammer | Wikipedia | 159 | 5489731 | https://en.wikipedia.org/wiki/Reflex%20hammer | Technology | Devices | null |
A water tower is an elevated structure supporting a water tank constructed at a height sufficient to pressurize a distribution system for potable water, and to provide emergency storage for fire protection. Water towers often operate in conjunction with underground or surface service reservoirs, which store treated wat... | Water tower | Wikipedia | 501 | 44958 | https://en.wikipedia.org/wiki/Water%20tower | Technology | Food, water and health | null |
Water towers were used to supply water stops for steam locomotives on railroad lines. Early steam locomotives required water stops every .
Design and construction
A variety of materials can be used to construct a typical water tower; steel and reinforced or prestressed concrete are most often used (with wood, fiberg... | Water tower | Wikipedia | 475 | 44958 | https://en.wikipedia.org/wiki/Water%20tower | Technology | Food, water and health | null |
The technology dates to at least the 19th century, and for a long time New York City required that all buildings higher than six stories be equipped with a rooftop water tower. Two companies in New York build water towers, both of which are family businesses in operation since the 19th century.
The original water towe... | Water tower | Wikipedia | 501 | 44958 | https://en.wikipedia.org/wiki/Water%20tower | Technology | Food, water and health | null |
Some water towers are also used as observation towers, and some restaurants, such as the Goldbergturm in Sindelfingen, Germany, or the second of the three Kuwait Towers, in the State of Kuwait. It is also common to use water towers as the location of transmission mechanisms in the UHF range with small power, for instan... | Water tower | Wikipedia | 463 | 44958 | https://en.wikipedia.org/wiki/Water%20tower | Technology | Food, water and health | null |
Water towers can be surrounded by ornate coverings including fancy brickwork, a large ivy-covered trellis or they can be simply painted. Some city water towers have the name of the city painted in large letters on the roof, as a navigational aid to aviators and motorists. Sometimes the decoration can be humorous. An ex... | Water tower | Wikipedia | 511 | 44958 | https://en.wikipedia.org/wiki/Water%20tower | Technology | Food, water and health | null |
Slovenia
Brežice Water Tower in Brežice
Sweden
Vanadislundens water reservoir (Stockholm)
United Kingdom
Cardiff Central Station Water Tower
Dock Tower in Grimsby
House in the Clouds in Thorpeness, Suffolk
Jumbo in Colchester, Essex
Norton Water Tower in Norton, Cheshire
Tilehurst Water Tower in Reading
T... | Water tower | Wikipedia | 342 | 44958 | https://en.wikipedia.org/wiki/Water%20tower | Technology | Food, water and health | null |
Addison Standpipe, in Addison, Michigan
Belton Standpipe in Belton, South Carolina (also in Allendale and Walterboro)
Belton Standpipe in Belton, Texas
Bellevue Standpipe (actually a water tank, not a tower), in Boston, Massachusetts
Chicago Water Tower, in Chicago, Illinois
Cochituate standpipe, in Boston, Massac... | Water tower | Wikipedia | 240 | 44958 | https://en.wikipedia.org/wiki/Water%20tower | Technology | Food, water and health | null |
A likelihood function (often simply called the likelihood) measures how well a statistical model explains observed data by calculating the probability of seeing that data under different parameter values of the model. It is constructed from the joint probability distribution of the random variable that (presumably) gen... | Likelihood function | Wikipedia | 455 | 44968 | https://en.wikipedia.org/wiki/Likelihood%20function | Mathematics | Specific functions | null |
Consider a simple statistical model of a coin flip: a single parameter that expresses the "fairness" of the coin. The parameter is the probability that a coin lands heads up ("H") when tossed. can take on any value within the range 0.0 to 1.0. For a perfectly fair coin, .
Imagine flipping a fair coin twice, and obse... | Likelihood function | Wikipedia | 511 | 44968 | https://en.wikipedia.org/wiki/Likelihood%20function | Mathematics | Specific functions | null |
The above discussion of the likelihood for discrete random variables uses the counting measure, under which the probability density at any outcome equals the probability of that outcome.
Likelihoods for mixed continuous–discrete distributions
The above can be extended in a simple way to allow consideration of distribu... | Likelihood function | Wikipedia | 480 | 44968 | https://en.wikipedia.org/wiki/Likelihood%20function | Mathematics | Specific functions | null |
which may include the points at infinity if is unbounded. Mäkeläinen and co-authors prove this result using Morse theory while informally appealing to a mountain pass property. Mascarenhas restates their proof using the mountain pass theorem.
In the proofs of consistency and asymptotic normality of the maximum likeli... | Likelihood function | Wikipedia | 453 | 44968 | https://en.wikipedia.org/wiki/Likelihood%20function | Mathematics | Specific functions | null |
The likelihood ratio is also of central importance in Bayesian inference, where it is known as the Bayes factor, and is used in Bayes' rule. Stated in terms of odds, Bayes' rule states that the posterior odds of two alternatives, and , given an event , is the prior odds, times the likelihood ratio. As an equation:
Th... | Likelihood function | Wikipedia | 373 | 44968 | https://en.wikipedia.org/wiki/Likelihood%20function | Mathematics | Specific functions | null |
Given a model, likelihood intervals can be compared to confidence intervals. If is a single real parameter, then under certain conditions, a 14.65% likelihood interval (about 1:7 likelihood) for will be the same as a 95% confidence interval (19/20 coverage probability). In a slightly different formulation suited to t... | Likelihood function | Wikipedia | 448 | 44968 | https://en.wikipedia.org/wiki/Likelihood%20function | Mathematics | Specific functions | null |
Since graphically the procedure of concentration is equivalent to slicing the likelihood surface along the ridge of values of the nuisance parameter that maximizes the likelihood function, creating an isometric profile of the likelihood function for a given , the result of this procedure is also known as profile likel... | Likelihood function | Wikipedia | 485 | 44968 | https://en.wikipedia.org/wiki/Likelihood%20function | Mathematics | Specific functions | null |
Log-likelihood function is the logarithm of the likelihood function, often denoted by a lowercase or , to contrast with the uppercase or for the likelihood. Because logarithms are strictly increasing functions, maximizing the likelihood is equivalent to maximizing the log-likelihood. But for practical purposes it is... | Likelihood function | Wikipedia | 472 | 44968 | https://en.wikipedia.org/wiki/Likelihood%20function | Mathematics | Specific functions | null |
The term was coined by A. W. F. Edwards in the context of statistical hypothesis testing, i.e. whether or not the data "support" one hypothesis (or parameter value) being tested more than any other.
The log-likelihood function being plotted is used in the computation of the score (the gradient of the log-likelihood) a... | Likelihood function | Wikipedia | 492 | 44968 | https://en.wikipedia.org/wiki/Likelihood%20function | Mathematics | Specific functions | null |
The and each correspond to a change of coordinates, so in these coordinates, the log-likelihood of an exponential family is given by the simple formula:
In words, the log-likelihood of an exponential family is inner product of the natural parameter and the sufficient statistic , minus the normalization factor (log-... | Likelihood function | Wikipedia | 454 | 44968 | https://en.wikipedia.org/wiki/Likelihood%20function | Mathematics | Specific functions | null |
Interpretations under different foundations
Among statisticians, there is no consensus about what the foundation of statistics should be. There are four main paradigms that have been proposed for the foundation: frequentism, Bayesianism, likelihoodism, and AIC-based. For each of the proposed foundations, the interpreta... | Likelihood function | Wikipedia | 404 | 44968 | https://en.wikipedia.org/wiki/Likelihood%20function | Mathematics | Specific functions | null |
The specific calculation of the likelihood is the probability that the observed sample would be assigned, assuming that the model chosen and the values of the several parameters θ give an accurate approximation of the frequency distribution of the population that the observed sample was drawn from. Heuristically, it ma... | Likelihood function | Wikipedia | 476 | 44968 | https://en.wikipedia.org/wiki/Likelihood%20function | Mathematics | Specific functions | null |
Oil shale is an organic-rich fine-grained sedimentary rock containing kerogen (a solid mixture of organic chemical compounds) from which liquid hydrocarbons can be produced. In addition to kerogen, general composition of oil shales constitutes inorganic substance and bitumens. Based on their deposition environment, oil... | Oil shale | Wikipedia | 388 | 45010 | https://en.wikipedia.org/wiki/Oil%20shale | Physical sciences | Petrology | null |
Oil shale, an organic-rich sedimentary rock, belongs to the group of sapropel fuels. It does not have a definite geological definition nor a specific chemical formula, and its seams do not always have discrete boundaries. Oil shales vary considerably in their mineral content, chemical composition, age, type of kerogen... | Oil shale | Wikipedia | 347 | 45010 | https://en.wikipedia.org/wiki/Oil%20shale | Physical sciences | Petrology | null |
General composition of oil shales constitutes inorganic matrix, bitumens, and kerogen. While the bitumen portion of oil shales is soluble in carbon disulfide, the kerogen portion is insoluble in carbon disulfide and may contain iron, vanadium, nickel, molybdenum, and uranium. Oil shale contains a lower percentage of ... | Oil shale | Wikipedia | 436 | 45010 | https://en.wikipedia.org/wiki/Oil%20shale | Physical sciences | Petrology | null |
As source rocks for most conventional oil reservoirs, oil shale deposits are found in all world oil provinces, although most of them are too deep to be exploited economically. As with all oil and gas resources, analysts distinguish between oil shale resources and oil shale reserves. "Resources" refer to all oil shale ... | Oil shale | Wikipedia | 424 | 45010 | https://en.wikipedia.org/wiki/Oil%20shale | Physical sciences | Petrology | null |
In the 10th century, the Arab physician Masawaih al-Mardini (Mesue the Younger) described a method of extraction of oil from "some kind of bituminous shale". The first patent for extracting oil from oil shale was British Crown Patent 330 granted in 1694 to Martin Eele, Thomas Hancock and William Portlock, who had "foun... | Oil shale | Wikipedia | 457 | 45010 | https://en.wikipedia.org/wiki/Oil%20shale | Physical sciences | Petrology | null |
The global oil-shale industry began to revive at the beginning of the 21st century. In 2003, an oil-shale development program restarted in the United States. Authorities introduced a commercial leasing program permitting the extraction of oil shale and oil sands on federal lands in 2005, in accordance with the Energy P... | Oil shale | Wikipedia | 422 | 45010 | https://en.wikipedia.org/wiki/Oil%20shale | Physical sciences | Petrology | null |
Most exploitation of oil shale involves mining followed by shipping elsewhere, after which the shale is burned directly to generate electricity or undertakes further processing. The most common methods of mining involve open-pit mining and strip mining. These procedures remove most of the overlying material to expose t... | Oil shale | Wikipedia | 429 | 45010 | https://en.wikipedia.org/wiki/Oil%20shale | Physical sciences | Petrology | null |
Applications and products
Oil shale is utilized as a fuel for thermal power-plants, burning it (like coal) to drive steam turbines; some of these plants employ the resulting heat for district heating of homes and businesses. In addition to its use as a fuel, oil shale may also serve in the production of specialty carb... | Oil shale | Wikipedia | 248 | 45010 | https://en.wikipedia.org/wiki/Oil%20shale | Physical sciences | Petrology | null |
The shale oil derived from oil shale does not directly substitute for crude oil in all applications. It may contain higher concentrations of olefins, oxygen, and nitrogen than conventional crude oil. Some shale oils may have higher sulfur or arsenic content. By comparison with West Texas Intermediate, the benchmark st... | Oil shale | Wikipedia | 277 | 45010 | https://en.wikipedia.org/wiki/Oil%20shale | Physical sciences | Petrology | null |
The various attempts to develop oil shale deposits have succeeded only when the cost of shale-oil production in a given region comes in below the price of crude oil or its other substitutes (break-even price). According to a 2005 survey, conducted by the RAND Corporation, the cost of producing a barrel of oil at a surf... | Oil shale | Wikipedia | 450 | 45010 | https://en.wikipedia.org/wiki/Oil%20shale | Physical sciences | Petrology | null |
A critical measure of the viability of oil shale as an energy source lies in the ratio of the energy produced by the shale to the energy used in its mining and processing, a ratio known as "energy return on investment" (EROI). A 1984 study estimated the EROI of the various known oil-shale deposits as varying between 0.... | Oil shale | Wikipedia | 428 | 45010 | https://en.wikipedia.org/wiki/Oil%20shale | Physical sciences | Petrology | null |
Water concerns are sensitive issues in arid regions, such as the western U.S. and Israel's Negev Desert, where plans exist to expand oil-shale extraction despite a water shortage. Depending on technology, above-ground retorting uses between one and five barrels of water per barrel of produced shale-oil. A 2008 program... | Oil shale | Wikipedia | 223 | 45010 | https://en.wikipedia.org/wiki/Oil%20shale | Physical sciences | Petrology | null |
In category theory, a branch of mathematics, a natural transformation provides a way of transforming one functor into another while respecting the internal structure (i.e., the composition of morphisms) of the categories involved. Hence, a natural transformation can be considered to be a "morphism of functors". Informa... | Natural transformation | Wikipedia | 409 | 45022 | https://en.wikipedia.org/wiki/Natural%20transformation | Mathematics | Category theory | null |
Statements such as
"Every group is naturally isomorphic to its opposite group"
abound in modern mathematics. We will now give the precise meaning of this statement as well as its proof. Consider the category
of all groups with group homomorphisms as morphisms. If is a group, we define
its opposite group as follows... | Natural transformation | Wikipedia | 484 | 45022 | https://en.wikipedia.org/wiki/Natural%20transformation | Mathematics | Category theory | null |
Given commutative rings and with a ring homomorphism , the respective groups of invertible matrices and inherit a homomorphism which we denote by , obtained by applying
to each matrix entry. Similarly, restricts to a group homomorphism , where denotes the group of units of . In fact, and are functors from th... | Natural transformation | Wikipedia | 483 | 45022 | https://en.wikipedia.org/wiki/Natural%20transformation | Mathematics | Category theory | null |
The notion of a natural transformation is categorical, and states (informally) that a particular map between functors can be done consistently over an entire category. Informally, a particular map (esp. an isomorphism) between individual objects (not entire categories) is referred to as a "natural isomorphism", meaning... | Natural transformation | Wikipedia | 489 | 45022 | https://en.wikipedia.org/wiki/Natural%20transformation | Mathematics | Category theory | null |
However, the torus (which is abstractly a product of two circles) has fundamental group isomorphic to , but the splitting is not natural. Note the use of , , and :
This abstract isomorphism with a product is not natural, as some isomorphisms of do not preserve the product: the self-homeomorphism of (thought of as t... | Natural transformation | Wikipedia | 356 | 45022 | https://en.wikipedia.org/wiki/Natural%20transformation | Mathematics | Category theory | null |
The dual space of a finite-dimensional vector space is again a finite-dimensional vector space of the same dimension, and these are thus isomorphic, since dimension is the only invariant of finite-dimensional vector spaces over a given field. However, in the absence of additional constraints (such as a requirement that... | Natural transformation | Wikipedia | 469 | 45022 | https://en.wikipedia.org/wiki/Natural%20transformation | Mathematics | Category theory | null |
In this category (finite-dimensional vector spaces with a nondegenerate bilinear form, maps linear transforms that respect the bilinear form), the dual of a map between vector spaces can be identified as a transpose. Often for reasons of geometric interest this is specialized to a subcategory, by requiring that the non... | Natural transformation | Wikipedia | 511 | 45022 | https://en.wikipedia.org/wiki/Natural%20transformation | Mathematics | Category theory | null |
Interchange law
The two operations are related by an identity which exchanges vertical composition with horizontal composition: if we have four natural transformations as shown on the image to the right, then the following identity holds:
.
Vertical and horizontal compositions are also linked through identity natura... | Natural transformation | Wikipedia | 451 | 45022 | https://en.wikipedia.org/wiki/Natural%20transformation | Mathematics | Category theory | null |
If is an object of a locally small category , then the assignment defines a covariant functor . This functor is called representable (more generally, a representable functor is any functor naturally isomorphic to this functor for an appropriate choice of ). The natural transformations from a representable functor to ... | Natural transformation | Wikipedia | 299 | 45022 | https://en.wikipedia.org/wiki/Natural%20transformation | Mathematics | Category theory | null |
Biodiversity is the variability of life on Earth. It can be measured on various levels. There is for example genetic variability, species diversity, ecosystem diversity and phylogenetic diversity. Diversity is not distributed evenly on Earth. It is greater in the tropics as a result of the warm climate and high primary... | Biodiversity | Wikipedia | 507 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
Biodiversity is most commonly used to replace the more clearly-defined and long-established terms, species diversity and species richness. However, there is no concrete definition for biodiversity, as its definition continues to be defined. Other definitions include (in chronological order):
An explicit definition co... | Biodiversity | Wikipedia | 321 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
According to estimates by Mora et al. (2011), there are approximately 8.7 million terrestrial species and 2.2 million oceanic species. The authors note that these estimates are strongest for eukaryotic organisms and likely represent the lower bound of prokaryote diversity. Other estimates include:
220,000 vascular pla... | Biodiversity | Wikipedia | 431 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
In absolute terms, the planet has lost 58% of its biodiversity since 1970 according to a 2016 study by the World Wildlife Fund. The Living Planet Report 2014 claims that "the number of mammals, birds, reptiles, amphibians, and fish across the globe is, on average, about half the size it was 40 years ago". Of that numbe... | Biodiversity | Wikipedia | 487 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
Loss of biodiversity results in the loss of natural capital that supplies ecosystem goods and services. Species today are being wiped out at a rate 100 to 1,000 times higher than baseline, and the rate of extinctions is increasing. This process destroys the resilience and adaptability of life on Earth.
In 2006, many s... | Biodiversity | Wikipedia | 373 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
There is local biodiversity, which directly impacts daily life, affecting the availability of fresh water, food choices, and fuel sources for humans. Regional biodiversity includes habitats and ecosystems that synergizes and either overlaps or differs on a regional scale. National biodiversity within a country determin... | Biodiversity | Wikipedia | 431 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
The biodiversity of forests varies considerably according to factors such as forest type, geography, climate and soils – in addition to human use. Most forest habitats in temperate regions support relatively few animal and plant species and species that tend to have large geographical distributions, while the montane f... | Biodiversity | Wikipedia | 473 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
Biodiversity Hotspots
A biodiversity hotspot is a region with a high level of endemic species that have experienced great habitat loss. The term hotspot was introduced in 1988 by Norman Myers. While hotspots are spread all over the world, the majority are forest areas and most are located in the tropics.
Brazil's Atla... | Biodiversity | Wikipedia | 494 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
Biodiversity grew fast during the Phanerozoic (the last 540 million years), especially during the so-called Cambrian explosion—a period during which nearly every phylum of multicellular organisms first appeared. However, recent studies suggest that this diversification had started earlier, at least in the Ediacaran, an... | Biodiversity | Wikipedia | 469 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
Diversification
The existence of a global carrying capacity, limiting the amount of life that can live at once, is debated, as is the question of whether such a limit would also cap the number of species. While records of life in the sea show a logistic pattern of growth, life on land (insects, plants and tetrapods) sh... | Biodiversity | Wikipedia | 445 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
New species are regularly discovered (on average between 5–10,000 new species each year, most of them insects) and many, though discovered, are not yet classified (estimates are that nearly 90% of all arthropods are not yet classified). Most of the terrestrial diversity is found in tropical forests and in general, the ... | Biodiversity | Wikipedia | 474 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
There have been many claims about biodiversity's effect on the ecosystem services, especially provisioning and regulating services. Some of those claims have been validated, some are incorrect and some lack enough evidence to draw definitive conclusions.
Ecosystem services have been grouped in three types:
Provisioni... | Biodiversity | Wikipedia | 360 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
Greater species diversity
of fish increases the stability of fisheries yield (synthesis of 8 observational studies)
of plants increases carbon sequestration, but note that this finding only relates to actual uptake of carbon dioxide and not long-term storage; synthesis of 479 experimental studies)
of plants increase... | Biodiversity | Wikipedia | 459 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
Although about 80 percent of humans' food supply comes from just 20 kinds of plants, humans use at least 40,000 species. Earth's surviving biodiversity provides resources for increasing the range of food and other products suitable for human use, although the present extinction rate shrinks that potential.
Human healt... | Biodiversity | Wikipedia | 495 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
Cultural and aesthetic value
Philosophically it could be argued that biodiversity has intrinsic aesthetic and spiritual value to mankind in and of itself. This idea can be used as a counterweight to the notion that tropical forests and other ecological realms are only worthy of conservation because of the services they... | Biodiversity | Wikipedia | 437 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
Invasive species seem to increase local (alpha diversity) diversity, which decreases turnover of diversity (beta diversity). Overall gamma diversity may be lowered because species are going extinct because of other causes, but even some of the most insidious invaders (e.g.: Dutch elm disease, emerald ash borer, chestnu... | Biodiversity | Wikipedia | 470 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
Conservation biology is reforming around strategic plans to protect biodiversity. Preserving global biodiversity is a priority in strategic conservation plans that are designed to engage public policy and concerns affecting local, regional and global scales of communities, ecosystems and cultures. Action plans identify... | Biodiversity | Wikipedia | 337 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
Protected areas, including forest reserves and biosphere reserves, serve many functions including for affording protection to wild animals and their habitat. Protected areas have been set up all over the world with the specific aim of protecting and conserving plants and animals. Some scientists have called on the glob... | Biodiversity | Wikipedia | 473 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
Forest protected areas
Forest protected areas are a subset of all protected areas in which a significant portion of the area is forest. This may be the whole or only a part of the protected area. Globally, 18 percent of the world's forest area, or more than 700 million hectares, fall within legally established protecte... | Biodiversity | Wikipedia | 468 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
Citizen science
Citizen science, also known as public participation in scientific research, has been widely used in environmental sciences and is particularly popular in a biodiversity-related context. It has been used to enable scientists to involve the general public in biodiversity research, thereby enabling the sc... | Biodiversity | Wikipedia | 499 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
On the 19 of December 2022, during the 2022 United Nations Biodiversity Conference every country on earth, with the exception of the United States and the Holy See, signed onto the agreement which includes protecting 30% of land and oceans by 2030 (30 by 30) and 22 other targets intended to reduce biodiversity loss. Th... | Biodiversity | Wikipedia | 496 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
Uniform approval for use of biodiversity as a legal standard has not been achieved, however. Bosselman argues that biodiversity should not be used as a legal standard, claiming that the remaining areas of scientific uncertainty cause unacceptable administrative waste and increase litigation without promoting preservati... | Biodiversity | Wikipedia | 414 | 45086 | https://en.wikipedia.org/wiki/Biodiversity | Biology and health sciences | Biology | null |
The Hubble sequence is a morphological classification scheme for galaxies published by Edwin Hubble in 1926. It is often colloquially known as the Hubble tuning-fork diagram because the shape in which it is traditionally represented resembles a tuning fork.
It was invented by John Henry Reynolds and Sir James Jeans.
T... | Hubble sequence | Wikipedia | 447 | 45145 | https://en.wikipedia.org/wiki/Hubble%20sequence | Physical sciences | Galaxy classification | Astronomy |
At the centre of the Hubble tuning fork, where the two spiral-galaxy branches and the elliptical branch join, lies an intermediate class of galaxies known as lenticulars and given the symbol S0. These galaxies consist of a bright central bulge, similar in appearance to an elliptical galaxy, surrounded by an extended, d... | Hubble sequence | Wikipedia | 378 | 45145 | https://en.wikipedia.org/wiki/Hubble%20sequence | Physical sciences | Galaxy classification | Astronomy |
On the right of the Hubble sequence diagram are two parallel branches encompassing the spiral galaxies. A spiral galaxy consists of a flattened disk, with stars forming a (usually two-armed) spiral structure, and a central concentration of stars known as the bulge. Roughly half of all spirals are also observed to have ... | Hubble sequence | Wikipedia | 493 | 45145 | https://en.wikipedia.org/wiki/Hubble%20sequence | Physical sciences | Galaxy classification | Astronomy |
Galaxies that do not fit into the Hubble sequence, because they have no regular structure (either disk-like or ellipsoidal), are termed irregular galaxies. Hubble defined two classes of irregular galaxy:
Irr I galaxies have asymmetric profiles and lack a central bulge or obvious spiral structure; instead they contain ... | Hubble sequence | Wikipedia | 274 | 45145 | https://en.wikipedia.org/wiki/Hubble%20sequence | Physical sciences | Galaxy classification | Astronomy |
Elliptical and lenticular galaxies are commonly referred to together as "early-type" galaxies, while spirals and irregular galaxies are referred to as "late types". This nomenclature is the source of the common, but erroneous, belief that the Hubble sequence was intended to reflect a supposed evolutionary sequence, fro... | Hubble sequence | Wikipedia | 423 | 45145 | https://en.wikipedia.org/wiki/Hubble%20sequence | Physical sciences | Galaxy classification | Astronomy |
Another criticism of the Hubble classification scheme is that, being based on the appearance of a galaxy in a two-dimensional image, the classes are only indirectly related to the true physical properties of galaxies. In particular, problems arise because of orientation effects. The same galaxy would look very differen... | Hubble sequence | Wikipedia | 256 | 45145 | https://en.wikipedia.org/wiki/Hubble%20sequence | Physical sciences | Galaxy classification | Astronomy |
In computer architecture, 8-bit integers or other data units are those that are 8 bits wide (1 octet). Also, 8-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers or data buses of that size. Memory addresses (and thus address buses) for 8-bit CPUs are ge... | 8-bit computing | Wikipedia | 504 | 45148 | https://en.wikipedia.org/wiki/8-bit%20computing | Technology | Computer architecture concepts | null |
The 1976 Zilog Z80, one of the most popular 8-bit CPUs (though with 4-bit ALU, at least in the original), was discontinued in 2024 (its product line Z84C00), with Last Time Buy (LTB) orders by June 14, 2024.
Details
An 8-bit register can store 28 different values. The range of integer values that can be stored in 8 ... | 8-bit computing | Wikipedia | 446 | 45148 | https://en.wikipedia.org/wiki/8-bit%20computing | Technology | Computer architecture concepts | null |
While in general 8-bit CPUs have 16-bit addressing, in some architectures you have both, such as in the MOS Technology 6502 CPU, where the zero page is used extensively, saving one byte in the instructions accessing that page, and also having 16-bit addressing instructions that take 2 bytes for the address plus 1 for t... | 8-bit computing | Wikipedia | 368 | 45148 | https://en.wikipedia.org/wiki/8-bit%20computing | Technology | Computer architecture concepts | null |
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