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Alfredo Andreini (27 July 1870, in Florence – 11 December 1943, in Lippiano) was an Italian physician and entomologist. He carried out a large collection of insects collected in particular from Cape Verde (1908) and in Libya (1913) and Eritrea. He collaborated with the zoological museum La Specola. In geometry, he enumerated and published a list of 25 convex uniform honeycombs in 1905 (the space-filling tessellations of regular and semiregular polyhedra). This was the most complete list published until approximately 1991 when Norman Johnson completed the full list of 28 forms. | https://en.wikipedia.org/wiki?curid=8799882 |
Jet (fluid) A jet is a stream of fluid that is projected into a surrounding medium, usually from some kind of a nozzle, aperture or orifice. Jets can travel long distances without dissipating. Jet fluid has higher momentum compared to the surrounding fluid medium. In the case that the surrounding medium is assumed to be made up of the same fluid as the jet, and this fluid has a viscosity, the surrounding fluid is carried along with the jet in a process called entrainment. Some animals, notably cephalopods, move by jet propulsion, as do rocket engines and jet engines. | https://en.wikipedia.org/wiki?curid=8815697 |
Thermo-hygrograph A thermo-hygrograph or hygrothermograph is a chart recorder that measures and records both temperature and humidity (or dew point). Similar devices that record only one parameter are a thermograph for temperature and hygrograph for humidity. Thermographs where the variations are recorded using photography were described by several scientists as early as 1845, including Francis Ronalds who was Honorary Director of the Kew Observatory. An updated model of the initial machine was deployed across the national observational network set up by the new UK Met Office in 1867 and coordinated by Kew Observatory. These instruments then saw extended use around the world. An alternative thermograph configuration has a pen that records temperature on a revolving cylinder. The pen is at the end of a lever that is controlled by a bi-metal strip of temperature-sensitive metal which bends as the temperature changes. A human hair bundle can be used for humidity in such machines. | https://en.wikipedia.org/wiki?curid=8838269 |
John Robert Anderson (chemist) John Robert Anderson (5 March 1928 – 26 February 2007) was an Australian chemist whose research specialised on materials science. Anderson served as Chief of the Division of Material Sciences at the Commonwealth Scientific and Industrial Research Organisation from 1970 to 1978. He attended Sydney Boys High School from 1940 to 1944. | https://en.wikipedia.org/wiki?curid=8845939 |
Ponderomotive energy In strong-field laser physics, ponderomotive energy is the cycle-averaged quiver energy of a free electron in an electromagnetic field. The ponderomotive energy is given by where formula_2 is the electron charge, formula_3 is the linearly polarised electric field amplitude, formula_4 is the laser carrier frequency and formula_5 is the electron mass. In terms of the laser intensity formula_6, using formula_7, it reads less simply: where formula_9 is the vacuum permittivity. In atomic units, formula_10, formula_11, formula_12 where formula_13. If one uses the atomic unit of electric field, then the ponderomotive energy is just The formula for the ponderomotive energy can be easily derived. A free particle of charge formula_15 interacts with an electric field formula_16. The force on the charged particle is The acceleration of the particle is Because the electron executes harmonic motion, the particle's position is For a particle experiencing harmonic motion, the time-averaged energy is In laser physics, this is called the ponderomotive energy formula_21. | https://en.wikipedia.org/wiki?curid=8853472 |
Ostriker–Peebles criterion In astronomy, the Ostriker–Peebles criterion, named after its discoverers Jeremiah Ostriker and Jim Peebles, describes the formation of barred galaxies. The rotating disc of a spiral galaxy, consisting of stars and solar systems, may become unstable in a way that the stars in the outer parts of the "arms" are released from the galaxy system, resulting in the collapse of the remaining stars into a bar-shaped galaxy. This occurs in approximately 1/3 of the known spiral galaxies. Based on the first kinetic energy component "T" and the total gravitational energy "W", a galaxy will become barred when formula_1. | https://en.wikipedia.org/wiki?curid=8854508 |
International Congress of Quantum Chemistry The (ICQC), is an international conference dedicated to the field of quantum chemistry. It is organized by the International Academy of Quantum Molecular Science. The first conference was held from July 4-10, 1973 in Menton, France. The first conference marked the "50th anniversary of the discovery of wave mechanics". In chronological order: The sixteenth ICQC will be held in Menton in June 18-23 2018 (https://icqc16.sciencesconf.org). Papers from the Congresses have been published by the International Journal of Quantum Chemistry (IJQC). | https://en.wikipedia.org/wiki?curid=8865790 |
Axenic In biology, axenic describes the state of a culture in which only a single species, variety, or strain of organism is present and entirely free of all other contaminating organisms. The earliest axenic cultures were of bacteria or unicellular eukaryotes, but axenic cultures of many multicellular organisms are also possible. culture is an important tool for the study of symbiotic and parasitic organisms in a controlled environment. cultures of microorganisms are typically prepared by subculture of an existing mixed culture. This may involve use of a dilution series, in which a culture is successively diluted to the point where subsamples of it contain only a few individual organisms, ideally only a single individual (in the case of an asexual species). These subcultures are allowed to grow until the identity of their constituent organisms can be ascertained. Selection of those cultures consisting solely of the desired organism produces the axenic culture. Subculture selection may also involve manually sampling the target organism from an uncontaminated growth front in an otherwise mixed culture, and using this as an inoculum source for the subculture. cultures are usually checked routinely to ensure that they remain axenic. One standard approach with microorganisms is to spread a sample of the culture onto an agar plate, and to incubate this for a fixed period of time. The agar should be an enriched medium that will support the growth of common "contaminating" organisms | https://en.wikipedia.org/wiki?curid=8868378 |
Axenic Such "contaminating" organisms will grow on the plate during this period, identifying cultures that are no longer axenic. As axenic cultures are derived from very few organisms, or even a single individual, they are useful because the organisms present within them share a relatively narrow gene pool. In the case of an asexual species derived from a single individual, the resulting culture should consist of identical organisms (though processes such as mutation and horizontal gene transfer may introduce a degree of variability). Consequently, they will generally respond in a more uniform and reproducible fashion, simplifying the interpretation of experiments. The axenic culture of some pathogens is complicated because they normally thrive within host tissues which exhibit properties that are difficult to replicate "in vitro". This is especially true in the case of intracellular pathogens. However, careful replication of key features of the host environment can resolve these difficulties (e.g. host metabolites, dissolved oxygen), such as with the Q fever pathogen, "Coxiella burnetii". | https://en.wikipedia.org/wiki?curid=8868378 |
Bo Lawergren is a Professor Emeritus of Physics at Hunter College, The City University of New York. He received his PhD in Nuclear physics from the Australian National University of Canberra, Australia. | https://en.wikipedia.org/wiki?curid=8872282 |
Kirchhoff equations In fluid dynamics, the Kirchhoff equations, named after Gustav Kirchhoff, describe the motion of a rigid body in an ideal fluid. where formula_2 and formula_3 are the angular and linear velocity vectors at the point formula_4, respectively; formula_5 is the moment of inertia tensor, formula_6 is the body's mass; formula_7 is a unit normal to the surface of the body at the point formula_4; formula_9 is a pressure at this point; formula_10 and formula_11 are the hydrodynamic torque and force acting on the body, respectively; formula_12 and formula_13 likewise denote all other torques and forces acting on the body. The integration is performed over the fluid-exposed portion of the body's surface. If the body is completely submerged body in an infinitely large volume of irrotational, incompressible, inviscid fluid, that is at rest at infinity, then the vectors formula_10 and formula_11 can be found via explicit integration, and the dynamics of the body is described by the Kirchhoff – Clebsch equations: Their first integrals read Further integration produces explicit expressions for position and velocities. | https://en.wikipedia.org/wiki?curid=8884972 |
Jules-Émile Verschaffelt (27 January 1870, Ghent – 22 December 1955) was a Belgian physicist. He worked at Kamerlingh Onnes's laboratory in Leiden from 1894 to 1906 and once again from 1914 to 1923. From 1906 to 1914 he worked at the Vrije Universiteit Brussel and from 1923 to 1940 at the Ghent University. | https://en.wikipedia.org/wiki?curid=8887225 |
NGC 4194 NGC 4194, the Medusa merger, is a pair of interacting galaxies in the constellation Ursa Major. A region of extreme star formation across exists in the center of the Eye of Medusa, the central gas-rich region. | https://en.wikipedia.org/wiki?curid=8893870 |
BioCyc database collection The is an assortment of organism specific Pathway/ Genome Databases (PGDBs). They provide reference to genome and metabolic pathway information for thousands of organisms. As of December 2016, there are 9300 databases within BioCyc. SRI International, based in Menlo Park, California, maintains the BioCyc database family. Categories of Databases within BioCyc: Based on the manual curation done, BioCyc database family is divided into 3 tiers: Tier 1: Databases which have received at least one year of literature based manual curation. Currently there are seven databases in Tier 1. Out of the seven, MetaCyc is a major database that contains almost 2500 metabolic pathways from many organisms. The other important Tier 1 database is HumanCyc which contains around 300 metabolic pathways found in humans. The remaining five databases include, EcoCyc ("E. coli"), AraCyc ("Arabidopsis thaliana"), YeastCyc ("Saccharomyces cerevisiae"), LeishCyc ("Leishmania major Friedlin") and TrypanoCyc ("Trypanosoma brucei"). Tier 2: Databases that were computationally predicted but have received moderate manual curation (most with 1–4 months curation). Tier 2 Databases are available for manual curation by scientists who are interested in any particular organism. Tier 2 databases currently contain 43 different organism databases. Tier 3: Databases that were computationally predicted by PathoLogic and received no manual curation. As with Tier 2, Tier 3 databases are also available for curation for interested scientists | https://en.wikipedia.org/wiki?curid=8894516 |
BioCyc database collection Software Tools within BioCyc: The BioCyc website contains a variety of software tools for searching, visualizing, comparing, and analyzing genome and pathway information. It includes a genome browser, and browsers for metabolic and regulatory networks. The website also includes tools for painting large-scale ("omics") datasets onto metabolic and regulatory networks, and onto the genome. Use of BioCyc Database Collection in Research: Since BioCyc Database family comprises a long list of organism specific databases and also data at different systems level in a living system, the usage in research has been in a wide variety of context. Here, two studies are highlighted which show two different varieties of uses, one on a genome scale and other on identifying specific SNPs (Single Nucleotide Polymorphisms) within a genome. AlgaGEM AlgaGEM is a genome scale metabolic network model for a compartmentalized algae cell developed by Gomes de Oliveira Dal’Molin et al. based on the "Chlamydomonas reinhardtii" genome. It has 866 unique ORFs, 1862 metabolites, 2499 gene-enzyme-reaction-association entries, and 1725 unique reactions. One of the Pathway databases used for reconstruction is MetaCyc. SNPs The study by Shimul Chowdhury et al. showed association differed between maternal SNPs and metabolites involved in homocysteine, folate, and transsulfuration pathways in cases with Congenital Heart Defects (CHDs) as opposed to controls. The study used HumanCyc to select candidate genes and SNPs. | https://en.wikipedia.org/wiki?curid=8894516 |
William D. Francis William Douglas Francis (6 March 1889 – 2 January 1959) was a notable Australian botanist. Born in Bega, New South Wales, at the age of 17 he moved with his father Alfred, and brother Frederick, from Wollongong, New South Wales, where he attended Wollongong Superior Public School, to Kin Kin, Queensland. It was here that he was able to satisfy his strong interest in natural history while helping his father and brother on the farm. In 1919 he was appointed Assistant Government Botanist at the Queensland Herbarium. By 1950 he was appointed Government Botanist. He retired in 1954 and died five years later. He contributed enormously to the classification and identification of Australian rainforest species and is probably best remembered for his book "Australian Rainforest Trees". First published in 1929, it has since gone through numerous reprints. An arboretum established at Kin Kin in the 1990s is dedicated to his memory. | https://en.wikipedia.org/wiki?curid=8899030 |
Corona poling is a technique in optoelectronics. Corona discharge is a partial breakdown of air, usually at atmospheric pressure, and is initiated by a discharge in an inhomogeneous electric field (see Figure 1). Corona discharge has been used to pole films of electro-optic materials to enhance their electro-optic properties. Although corona poling can be performed at room temperature, poling at elevated temperature has several advantages. For example, raising the temperature in a polymer guest-host system close to its glass-rubber transition temperature before poling increases the mobility of the guest molecules and allows rotation to occur during poling. If during poling the temperature is lowered well below the transition temperature, the guest molecules are fixed in their new orientation. | https://en.wikipedia.org/wiki?curid=8906641 |
Miguel Ángel Virasoro (physicist) Miguel Ángel Virasoro (; born 1940 in Argentina) is an Argentine physicist who has done most of his work in Italy. The Shapiro–Virasoro model, the Virasoro algebra, the Virasoro constraint, and the Virasoro minimal model are named after him. Together with Giorgio Parisi and Marc Mézard Virasoro discovered the Ultrametric organization of low temperature spin glass states in infinite dimensions. He was a director of the International Centre for Theoretical Physics (ICTP) from 1995 to 2002. He taught physical-mathematical models for economy at Università di Roma "La Sapienza". He now teaches electromagnetism at "La Sapienza". | https://en.wikipedia.org/wiki?curid=8911332 |
Helix–coil transition model Helix–coil transition models are formalized techniques in statistical mechanics developed to describe conformations of linear polymers in solution. The models are usually but not exclusively applied to polypeptides as a measure of the relative fraction of the molecule in an alpha helix conformation versus turn or random coil. The main attraction in investigating alpha helix formation is that one encounters many of the features of protein folding but in their simplest version. Most of the helix–coil models contain parameters for the likelihood of helix nucleation from a coil region, and helix propagation along the sequence once nucleated; because polypeptides are directional and have distinct N-terminal and C-terminal ends, propagation parameters may differ in each direction. The two states are Common transition models include the Zimm–Bragg model and the Lifson–Roig model, and their extensions and variations. Energy of host poly-alanine helix in aqueous solution: where "m" is number of residues in the helix. | https://en.wikipedia.org/wiki?curid=8914599 |
Racah parameter When an atom has more than one electron there will be some electrostatic repulsion between those electrons. The amount of repulsion varies from atom to atom, depending upon the number and spin of the electrons and the orbitals they occupy. The total repulsion can be expressed in terms of three parameters "A", "B" and "C" which are known as the Racah parameters after Giulio Racah, who first described them. They are generally obtained empirically from gas-phase spectroscopic studies of atoms. They are often used in transition-metal chemistry to describe the repulsion energy associated with an electronic term. For example, the interelectronic repulsion of a P term is "A" + 7"B", and of a F term is "A" - 8"B", and the difference between them is therefore 15"B". The Racah parameters are defined as formula_1 where formula_2 are Slater integrals formula_3 and formula_4 are the Slater-Condon parameters formula_5 where formula_6 is the normalized radial part of an electron orbital, formula_7 and formula_8 | https://en.wikipedia.org/wiki?curid=8921722 |
Modulation sphere The or M-space formulation is a scheme or theory representing the system of effects of phase modulation and amplitude modulation as applied together on a carrier wave. The relations between both modulations on the carrier are also accounted for. The modulation sphere representation relates three variables in three space, M1, M2 and M3: | https://en.wikipedia.org/wiki?curid=8921792 |
South wind A south wind is a wind that originates in the south and blows north. Words used in English to describe the south wind are auster, buster (a violent south gale), föhn/foehn (alps), gibli (Libya with various spellings), friagem (a cold south wind blowing into Brazil from the Antarctic), khamsin (a hot spring wind in Egypt, with various spellings), kona (stormy southwest wind in Hawaii), notus (see mythology below for origin) and sirocco (North Africa). In Greek mythology, Notus was the god of the south wind and bringer of the storms of late summer and autumn. In Egyptian mythology, Shehbui is the god of the south wind. He was depicted as a man with the head of a lion. In Native American Iroquois tradition, the south wind is brought by the Fawn, and has a warm and gentle temperament reminiscent of the sweet flowers, babbling brooks, and the voices of birds of summer. In Basque mythology, Egoi was a minor deity associated with the south wind. | https://en.wikipedia.org/wiki?curid=8923963 |
West wind A west wind is a wind that blows from the west, in an eastward direction. In European tradition, it has usually been considered the mildest and most favorable of the directional winds. In Greek mythology, Zephyrus was the personification of the west wind and the bringer of light spring and early summer breezes; his Roman equivalent was Favonius (hence the adjective "favonian", pertaining to the west wind). In Egyptian mythology, Ḥutchai is the god of the west wind. He was depicted as a man with the head of a serpent. Geoffrey Chaucer wrote of the "swete breth" of Zephyrus, and a soft, gentle breeze may be referred to as a zephyr, as in William Shakespeare's "Cymbeline" (IV, ii): "They are as gentle / As zephyrs blowing below the violet, / Not wagging his sweet head." In Iroquois tradition, the "west wind" is brought by the Panther, ugly and fierce. A west wind can be known as a zephyr. | https://en.wikipedia.org/wiki?curid=8924055 |
Hamed Gohar Prof. Hamed Abdel Fattah Goher (11/14 1907-1992) () was an Egyptian oceanographer, scientist and TV presenter. He appeared for over 18 years in his program 'The world of the seas'. He was not married and dedicated his life to the sea. Gohar initiated the first full-scale research in ocean studies in Egypt and the Arab countries. In 1931 he began research on Xenia, or soft corals of the Red Sea, finalized in 1939. In 1934 he published a study in the British journal, Nature, on 'The Partnership between Fish and Anemone'. Gohar's arduous eight-year research on the soft corals in Hurghada earned him a D.Sc. from Cambridge - considered the highest recognition open to unsupervised research. | https://en.wikipedia.org/wiki?curid=8934164 |
Pacific Ocean Shelf Tracking Project The (POST) is a field project of the Census of Marine Life that researches the behavior of marine animals through the use of ocean telemetry and data management systems. This system of telemetry consists of highly efficient lines of acoustic receivers that create sections of the continental shelf along the coast of the Pacific Northwest. The acoustic receivers pick up signals from the tagged animals as they pass along the lines, allowing for the documentation of movement patterns. The receivers also allow for the estimation of parameters such as swimming speed and mortality. The trackers sit on the seabed of the continental shelf and in the major rivers of the world. This method can be used to improve fishing skills and management. The program started in 2002 and was initially limited to the study of the movement and ocean-survival of both hatchery-raised and wild salmon in the Pacific Northwest. After the successful pilot period, the program has now moved into the tracking of trout, sharks, rockfish, and lingcod. | https://en.wikipedia.org/wiki?curid=8939340 |
Prompt gamma neutron activation analysis Prompt-gamma neutron activation analysis (PGAA) is a very widely applicable technique for determining the presence and amount of many elements simultaneously in samples ranging in size from micrograms to many grams. It is a non-destructive method, and the chemical form and shape of the sample are relatively unimportant. Typical measurements take from a few minutes to several hours per sample. The technique can be described as follows. The sample is continuously irradiated with a beam of neutrons. The constituent elements of the sample absorb some of these neutrons and emit prompt gamma rays which are measured with a gamma ray spectrometer. The energies of these gamma rays identify the neutron-capturing elements, while the intensities of the peaks at these energies reveal their concentrations. The amount of analyte element is given by the ratio of count rate of the characteristic peak in the sample to the rate in a known mass of the appropriate elemental standard irradiated under the same conditions. Typically, the sample will not acquire significant long-lived radioactivity, and the sample may be removed from the facility and used for other purposes. One of the typical applications of PGAA is an online belt elemental analyzer or bulk material analyzer used in cement, coal and mineral industries. | https://en.wikipedia.org/wiki?curid=8943611 |
List of polar-ring galaxies The following table lists polar-ring galaxies: Some galaxies feature a "polar ring" within the disk of the galaxy | https://en.wikipedia.org/wiki?curid=8949362 |
Cloud Appreciation Society The is a society founded by Gavin Pretor-Pinney from the United Kingdom in January 2005. The society aims to foster understanding and appreciation of clouds, and has over 50,000 members worldwide from 120 different countries, as of March 2020. Yahoo! named the society's website as "the most weird and wonderful find on the internet for 2005". The group and its founder were the focus of a BBC documentary "Cloudspotting", based on Pretor-Pinney's book "The Cloudspotter's Guide". During an episode of Taskmaster, comedian Hugh Dennis revealed he is a member of the society. | https://en.wikipedia.org/wiki?curid=8964357 |
Transfer-matrix method In statistical mechanics, the transfer-matrix method is a mathematical technique which is used to write the partition function into a simpler form. It was introduced in 1941 by Hans Kramers and Gregory Wannier. In many one dimensional lattice models, the partition function is first written as an "n"-fold summation over each possible microstate, and also contains an additional summation of each component's contribution to the energy of the system within each microstate. Higher dimensional models contain even more summations. For systems with more than a few particles, such expressions can quickly become too complex to work out directly, even by computer. Instead, the partition function can be rewritten in an equivalent way. The basic idea is to write the partition function in the form where v and v are vectors of dimension "p" and the "p" × "p" matrices W are the so-called transfer matrices. In some cases, particularly for systems with periodic boundary conditions, the partition function may be written more simply as where "tr" denotes the matrix trace. In either case, the partition function may be solved exactly using eigenanalysis. If the matrices are all the same matrix W, the partition function may be approximated as the "N" power of the largest eigenvalue of W, since the trace is the sum of the eigenvalues and the eigenvalues of the product of two diagonal matrices equals the product of their individual eigenvalues | https://en.wikipedia.org/wiki?curid=8964423 |
Transfer-matrix method The transfer-matrix method is used when the total system can be broken into a "sequence" of subsystems that interact only with adjacent subsystems. For example, a three-dimensional cubical lattice of spins in an Ising model can be decomposed into a sequence of two-dimensional planar lattices of spins that interact only adjacently. The dimension "p" of the "p" × "p" transfer matrix equals the number of states the subsystem may have; the transfer matrix itself W encodes the statistical weight associated with a particular state of subsystem "k" − 1 being next to another state of subsystem "k". As an example of observables that can be calculated from this method, the probability of a particular state formula_3 occurring at position "x" is given by: Where formula_5 is the projection matrix for state formula_3, having elements formula_7 Transfer-matrix methods have been critical for many exact solutions of problems in statistical mechanics, including the Zimm–Bragg and Lifson–Roig models of the helix-coil transition, transfer matrix models for protein-DNA binding, as well as the famous exact solution of the two-dimensional Ising model by Lars Onsager. | https://en.wikipedia.org/wiki?curid=8964423 |
Vegard's law In crystallography, materials science and metallurgy, is an empirical finding (heuristic approach) resembling the rule of mixtures. In 1921, Vegard discovered that the lattice parameter of a solid solution of two constituents is approximately a weighted mean of the two constituents' lattice parameters at the same temperature: e.g., in the case of a mixed oxide of uranium and plutonium as used in the fabrication of MOX nuclear fuel: assumes that both components A and B in their pure form (i.e. before mixing) have the same crystal structure. Here, is the lattice parameter of the solid solution, and are the lattice parameters of the pure constituents, and is the molar fraction of B in the solid solution. is seldom perfectly obeyed; often deviations from the linear behavior are observed. A detailed study of such deviations was conducted by King. However, it is often used in practice to obtain rough estimates when experimental data are not available for the lattice parameter for the system of interest. For systems known to approximately obey Vegard's law, the approximation may also be used to estimate the composition of a solution from knowledge of its lattice parameters, which are easily obtained from diffraction data. For example, consider the semiconductor compound . A relation exists between the constituent elements and their associated lattice parameters, , such that: When variations in lattice parameter are very small across the entire composition range, becomes equivalent to Amagat's law | https://en.wikipedia.org/wiki?curid=8981301 |
Vegard's law In many binary semiconducting systems, the band gap in semiconductors is approximately a linear function of the lattice parameter. Therefore, if the lattice parameter of a semiconducting system follows Vegard's law, one can also write a linear relationship between the band gap and composition. Using as before, the band gap energy, formula_4, can be written as: Sometimes, the linear interpolation between the band gap energies is not accurate enough, and a second term to account for the curvature of the band gap energies as a function of composition is added. This curvature correction is characterized by the bowing parameter, : The following excerpt from Takashi Fujii (1960) summarises well the limits of the Vegard’s law in the context of mineralogy and also makes the link with the Gladstone–Dale equation: When considering the empirical correlation of some physical properties and the chemical composition of solid compounds, other relationships, rules, or laws, also closely resembles the Vegard's law, and in fact the more general rule of mixtures: | https://en.wikipedia.org/wiki?curid=8981301 |
Erich Maren Schlaikjer (; November 22, 1905 in Newtown, Ohio – November 5, 1972) was an American geologist and dinosaur hunter. Assisting Barnum Brown, he co-described "Pachycephalosaurus" and what is now "Montanoceratops". Other discoveries include "Miotapirus" and a new species of "Mesohippus". Erich attended Harvard University, where he graduated with a bachelor's degree in 1929. He received master’s and doctoral degrees from Columbia University in 1931 and in 1935, respectively. Selected highlights of honors: | https://en.wikipedia.org/wiki?curid=8991562 |
Authigenesis is the process whereby a mineral or sedimentary rock deposit is generated where it is found or observed. Such deposits are described as authigenic. Authigenic sedimentary minerals form during sedimentation by precipitation or recrystallization instead of being transported from elsewhere (allogenic) by water or wind. Authigenic sediments are the main constituents of deep sea sedimentation. Authigenic clays tend to reduce the porosity of sediments, thus reducing permeability. In metamorphic petrology an authigenic mineral is one formed "in situ" during metamorphism, again by precipitation from fluids or recrystallization. For any mineral to be precipitated, the water must be oversaturated with respect to that mineral. For calcite, this means that the area of deposition must be above the carbonate compensation depth, or that the pore waters are sufficiently saturated due to dissolution of other grains that precipitation can begin. The alkalinity can also be reduced by microbial sulphate reduction. Neomorphism | https://en.wikipedia.org/wiki?curid=9004520 |
Langmuir Laboratory for Atmospheric Research The is a scientific laboratory studying the cloud processes that produce lightning, hail, and rain, located in the Magdalena Mountains of central New Mexico in the United States. The lab is operated by the New Mexico Institute of Mining and Technology (NM Tech) with funding from the National Science Foundation. The lab was founded in 1963, following pioneering research by E. J. Workman, former president of New Mexico Tech (then the New Mexico School of Mines), and others, including Irving Langmuir, the namesake of the laboratory. The earlier studies took place on the Plains of San Agustin and the San Mateo Mountains. The laboratory is located just south of South Baldy, the highest peak of the Magdalena mountains, at the southern end of the main ridge crest of the range, at an elevation of 10,679 ft (3,255 m). It occupies the Langmuir Research Site, a congressionally designated area within the Cibola National Forest, and operates under a Special Use Permit from the US Forest Service. | https://en.wikipedia.org/wiki?curid=9005363 |
NGC 6027 is a lenticular galaxy that is the brightest member of Seyfert's Sextet, a compact group of galaxies. Édouard Stephan discovered the galaxy in 1882. | https://en.wikipedia.org/wiki?curid=9007003 |
SNP genotyping is the measurement of genetic variations of single nucleotide polymorphisms (SNPs) between members of a species. It is a form of genotyping, which is the measurement of more general genetic variation. SNPs are one of the most common types of genetic variation. A SNP is a single base pair mutation at a specific locus, usually consisting of two alleles (where the rare allele frequency is > 1%). SNPs are found to be involved in the etiology of many human diseases and are becoming of particular interest in pharmacogenetics. Because SNPs are conserved during evolution, they have been proposed as markers for use in quantitative trait loci (QTL) analysis and in association studies in place of microsatellites. The use of SNPs is being extended in the HapMap project, which aims to provide the minimal set of SNPs needed to genotype the human genome. SNPs can also provide a genetic fingerprint for use in identity testing. The increase of interest in SNPs has been reflected by the furious development of a diverse range of methods. Several applications have been developed that interrogate SNPs by hybridizing complementary DNA probes to the SNP site. The challenge of this approach is reducing cross-hybridization between the allele-specific probes. This challenge is generally overcome by manipulating the hybridization stringency conditions. Dynamic allele-specific hybridization (DASH) genotyping takes advantage of the differences in the melting temperature in DNA that results from the instability of mismatched base pairs | https://en.wikipedia.org/wiki?curid=9007251 |
SNP genotyping The process can be vastly automated and encompasses a few simple principles. In the first step, a genomic segment is amplified and attached to a bead through a PCR reaction with a biotinylated primer. In the second step, the amplified product is attached to a streptavidin column and washed with NaOH to remove the unbiotinylated strand. An allele-specific oligonucleotide is then added in the presence of a molecule that fluoresces when bound to double-stranded DNA. The intensity is then measured as temperature is increased until the melting temperature (Tm) can be determined. A SNP will result in a lower than expected Tm. Because DASH genotyping is measuring a quantifiable change in Tm, it is capable of measuring all types of mutations, not just SNPs. Other benefits of DASH include its ability to work with label free probes and its simple design and performance conditions. SNP detection through molecular beacons makes use of a specifically engineered single-stranded oligonucleotide probe. The oligonucleotide is designed such that there are complementary regions at each end and a probe sequence located in between. This design allows the probe to take on a hairpin, or stem-loop, structure in its natural, isolated state. Attached to one end of the probe is a fluorophore and to the other end a fluorescence quencher. Because of the stem-loop structure of the probe, the fluorophore is in close proximity to the quencher, thus preventing the molecule from emitting any fluorescence | https://en.wikipedia.org/wiki?curid=9007251 |
SNP genotyping The molecule is also engineered such that only the probe sequence is complementary to the genomic DNA that will be used in the assay (Abravaya et al. 2003). If the probe sequence of the molecular beacon encounters its target genomic DNA during the assay, it will anneal and hybridize. Because of the length of the probe sequence, the hairpin segment of the probe will be denatured in favour of forming a longer, more stable probe-target hybrid. This conformational change permits the fluorophore and quencher to be free of their tight proximity due to the hairpin association, allowing the molecule to fluoresce. If on the other hand, the probe sequence encounters a target sequence with as little as one non-complementary nucleotide, the molecular beacon will preferentially stay in its natural hairpin state and no fluorescence will be observed, as the fluorophore remains quenched. The unique design of these molecular beacons allows for a simple diagnostic assay to identify SNPs at a given location. If a molecular beacon is designed to match a wild-type allele and another to match a mutant of the allele, the two can be used to identify the genotype of an individual. If only the first probe's fluorophore wavelength is detected during the assay then the individual is homozygous to the wild type. If only the second probe's wavelength is detected then the individual is homozygous to the mutant allele | https://en.wikipedia.org/wiki?curid=9007251 |
SNP genotyping Finally, if both wavelengths are detected, then both molecular beacons must be hybridizing to their complements and thus the individual must contain both alleles and be heterozygous. In high-density oligonucleotide SNP arrays, hundreds of thousands of probes are arrayed on a small chip, allowing for many SNPs to be interrogated simultaneously. Because SNP alleles only differ in one nucleotide and because it is difficult to achieve optimal hybridization conditions for all probes on the array, the target DNA has the potential to hybridize to mismatched probes. This is addressed somewhat by using several redundant probes to interrogate each SNP. Probes are designed to have the SNP site in several different locations as well as containing mismatches to the SNP allele. By comparing the differential amount of hybridization of the target DNA to each of these redundant probes, it is possible to determine specific homozygous and heterozygous alleles. Although oligonucleotide microarrays have a comparatively lower specificity and sensitivity, the scale of SNPs that can be interrogated is a major benefit. The Affymetrix Human SNP 5.0 GeneChip performs a genome-wide assay that can genotype over 500,000 human SNPs (Affymetrix 2007). A broad range of enzymes including DNA ligase, DNA polymerase and nucleases have been employed to generate high-fidelity methods. Restriction fragment length polymorphism (RFLP) is considered to be the simplest and earliest method to detect SNPs | https://en.wikipedia.org/wiki?curid=9007251 |
SNP genotyping SNP-RFLP makes use of the many different restriction endonucleases and their high affinity to unique and specific restriction sites. By performing a digestion on a genomic sample and determining fragment lengths through a gel assay it is possible to ascertain whether or not the enzymes cut the expected restriction sites. A failure to cut the genomic sample results in an identifiably larger than expected fragment implying that there is a mutation at the point of the restriction site which is rendering it protection from nuclease activity. Unfortunately, the combined factors of the high complexity of most eukaryotic genomes, the requirement for specific endonucleases, the fact that the exact mutation cannot necessarily be resolved in a single experiment, and the slow nature of gel assays make RFLP a poor choice for high throughput analysis. Tetra-primer amplification refractory mutation system PCR, or ARMS-PCR, employs two pairs of primers to amplify two alleles in one PCR reaction. The primers are designed such that the two primer pairs overlap at a SNP location but each match perfectly to only one of the possible SNPs. The basis of the invention is that unexpectedly, oligonucleotides with a mismatched 3'-residue will not function as primers in the PCR under appropriate conditions. As a result, if a given allele is present in the PCR reaction, the primer pair specific to that allele will produce product but not to the alternative allele with a different SNP | https://en.wikipedia.org/wiki?curid=9007251 |
SNP genotyping The two primer pairs are also designed such that their PCR products are of a significantly different length allowing for easily distinguishable bands by gel electrophoresis or melt temperature analysis. In examining the results, if a genomic sample is homozygous, then the PCR products that result will be from the primer that matches the SNP location and the outer opposite-strand primer, as well from the two outer primers. If the genomic sample is heterozygous, then products will result from the primer of each allele and their respective outer primer counterparts as well as the outer primers. An alternative strategy is to run multiple qPCR reactions with different primer sets that target each allele separately. Well-designed primers will amplify their target SNP at a much earlier cycle than the other SNPs. This allows more than two alleles to be distinguished, although an individual qPCR reaction is required for each SNP. To achieve high enough specificity, the primer sequence may require placement of an artificial mismatch near its 3'-end, which is an approach generally known as Taq-MAMA. Flap endonuclease (FEN) is an endonuclease that catalyzes structure-specific cleavage. This cleavage is highly sensitive to mismatches and can be used to interrogate SNPs with a high degree of specificity In the basic Invader assay, a FEN called cleavase is combined with two specific oligonucleotide probes, that together with the target DNA, can form a tripartite structure recognized by cleavase | https://en.wikipedia.org/wiki?curid=9007251 |
SNP genotyping The first probe, called the Invader oligonucleotide is complementary to the 3’ end of the target DNA. The last base of the Invader oligonucleotide is a non-matching base that overlaps the SNP nucleotide in the target DNA. The second probe is an allele-specific probe which is complementary to the 5’ end of the target DNA, but also extends past the 3’ side of the SNP nucleotide. The allele-specific probe will contain a base complementary to the SNP nucleotide. If the target DNA contains the desired allele, the Invader and allele-specific probes will bind to the target DNA forming the tripartite structure. This structure is recognized by cleavase, which will cleave and release the 3’ end of the allele-specific probe. If the SNP nucleotide in the target DNA is not complementary to the allele-specific probe, the correct tripartite structure is not formed and no cleavage occurs. The Invader assay is usually coupled with fluorescence resonance energy transfer (FRET) system to detect the cleavage event. In this setup, a quencher molecule is attached to the 3’ end and a fluorophore is attached to the 5’ end of the allele-specific probe. If cleavage occurs, the fluorophore will be separated from the quencher molecule generating a detectable signal. Only minimal cleavage occurs with mismatched probes making the Invader assay highly specific | https://en.wikipedia.org/wiki?curid=9007251 |
SNP genotyping However, in its original format, only one SNP allele could be interrogated per reaction sample and it required a large amount of target DNA to generate a detectable signal in a reasonable time frame. Several developments have extended the original Invader assay. By carrying out secondary FEN cleavage reactions, the Serial Invasive Signal Amplification Reaction (SISAR) allows both SNP alleles to be interrogated in a single reaction. SISAR Invader assay also requires less target DNA, improving the sensitivity of the original Invader assay. The assay has also been adapted in several ways for use in a high-throughput format. In one platform, the allele-specific probes are anchored to microspheres. When cleavage by FEN generates a detectable fluorescent signal, the signal is measured using flow-cytometry. The sensitivity of flow-cytometry, eliminates the need for PCR amplification of the target DNA (Rao et al. 2003). These high-throughput platforms have not progressed beyond the proof-of-principle stage and so far the Invader system has not been used in any large scale projects. Primer extension is a two step process that first involves the hybridization of a probe to the bases immediately upstream of the SNP nucleotide followed by a ‘mini-sequencing’ reaction, in which DNA polymerase extends the hybridized primer by adding a base that is complementary to the SNP nucleotide. This incorporated base is detected and determines the SNP allele (Goelet et al. 1999; Syvanen 2001) | https://en.wikipedia.org/wiki?curid=9007251 |
SNP genotyping Because primer extension is based on the highly accurate DNA polymerase enzyme, the method is generally very reliable. Primer extension is able to genotype most SNPs under very similar reaction conditions making it also highly flexible. The primer extension method is used in a number of assay formats. These formats use a wide range of detection techniques that include MALDI-TOF Mass spectrometry (see Sequenom) and ELISA-like methods. Generally, there are two main approaches which use the incorporation of either fluorescently labeled dideoxynucleotides (ddNTP) or fluorescently labeled deoxynucleotides (dNTP). With ddNTPs, probes hybridize to the target DNA immediately upstream of SNP nucleotide, and a single, ddNTP complementary to the SNP allele is added to the 3’ end of the probe (the missing 3'-hydroxyl in didioxynucleotide prevents further nucleotides from being added). Each ddNTP is labeled with a different fluorescent signal allowing for the detection of all four alleles in the same reaction. With dNTPs, allele-specific probes have 3’ bases which are complementary to each of the SNP alleles being interrogated. If the target DNA contains an allele complementary to the probe's 3’ base, the target DNA will completely hybridize to the probe, allowing DNA polymerase to extend from the 3’ end of the probe. This is detected by the incorporation of the fluorescently labeled dNTPs onto the end of the probe | https://en.wikipedia.org/wiki?curid=9007251 |
SNP genotyping If the target DNA does not contain an allele complementary to the probe's 3’ base, the target DNA will produce a mismatch at the 3’ end of the probe and DNA polymerase will not be able to extend from the 3' end of the probe. The benefit of the second approach is that several labeled dNTPs may get incorporated into the growing strand, allowing for increased signal. However, DNA polymerase in some rare cases, can extend from mismatched 3’ probes giving a false positive result. A different approach is used by "Sequenom"'s iPLEX method, which uses a MassARRAY mass spectrometer. Extension probes are designed in such a way that 40 different SNP assays can be amplified and analyzed in a PCR cocktail. The extension reaction uses ddNTPs as above, but the detection of the SNP allele is dependent on the actual mass of the extension product and not on a fluorescent molecule. This method is for low to medium high throughput, and is not intended for whole genome scanning. The flexibility and specificity of primer extension make it amenable to high throughput analysis. Primer extension probes can be arrayed on slides allowing for many SNPs to be genotyped at once. Broadly referred to as arrayed primer extension (APEX), this technology has several benefits over methods based on differential hybridization of probes | https://en.wikipedia.org/wiki?curid=9007251 |
SNP genotyping Comparatively, APEX methods have greater discriminating power than methods using this differential hybridization, as it is often impossible to obtain the optimal hybridization conditions for the thousands of probes on DNA microarrays (usually this is addressed by having highly redundant probes). However, the same density of probes cannot be achieved in APEX methods, which translates into lower output per run. Illumina Incorporated's Infinium assay is an example of a whole-genome genotyping pipeline that is based on primer extension method. In the Infinium assay, over 100,000 SNPs can be genotyped. The assay uses hapten-labelled nucleotides in a primer extension reaction. The hapten label is recognized by anti-bodies, which in turn are coupled to a detectable signal (Gunderson et al. 2006). APEX-2 is an arrayed primer extension genotyping method which is able to identify hundreds of SNPs or mutations in parallel using efficient homogeneous multiplex PCR (up to 640-plex) and four-color single-base extension on a microarray. The multiplex PCR requires two oligonucleotides per SNP/mutation generating amplicons that contain the tested base pair. The same oligonucleotides are used in the following step as immobilized single-base extension primers on a microarray (Krjutskov et al. 2008). Taq DNA polymerase's 5’-nuclease activity is used in the TaqMan assay for SNP genotyping | https://en.wikipedia.org/wiki?curid=9007251 |
SNP genotyping The TaqMan assay is performed concurrently with a PCR reaction and the results can be read in real-time as the PCR reaction proceeds (McGuigan & Ralston 2002). The assay requires forward and reverse PCR primers that will amplify a region that includes the SNP polymorphic site. Allele discrimination is achieved using FRET combined with one or two allele-specific probes that hybridize to the SNP polymorphic site. The probes will have a fluorophore linked to their 5’ end and a quencher molecule linked to their 3’ end. While the probe is intact, the quencher will remain in close proximity to the fluorophore, eliminating the fluorophore's signal. During the PCR amplification step, if the allele-specific probe is perfectly complementary to the SNP allele, it will bind to the target DNA strand and then get degraded by 5’-nuclease activity of the Taq polymerase as it extends the DNA from the PCR primers. The degradation of the probe results in the separation of the fluorophore from the quencher molecule, generating a detectable signal. If the allele-specific probe is not perfectly complementary, it will have lower melting temperature and not bind as efficiently. This prevents the nuclease from acting on the probe (McGuigan & Ralston 2002). Since the TaqMan assay is based on PCR, it is relatively simple to implement. The TaqMan assay can be multiplexed by combining the detection of up to seven SNPs in one reaction | https://en.wikipedia.org/wiki?curid=9007251 |
SNP genotyping However, since each SNP requires a distinct probe, the TaqMan assay is limited by the how close the SNPs can be situated. The scale of the assay can be drastically increased by performing many simultaneous reactions in microtitre plates. Generally, TaqMan is limited to applications that involve interrogating a small number of SNPs since optimal probes and reaction conditions must be designed for each SNP (Syvanen 2001). DNA ligase catalyzes the ligation of the 3' end of a DNA fragment to the 5' end of a directly adjacent DNA fragment. This mechanism can be used to interrogate a SNP by hybridizing two probes directly over the SNP polymorphic site, whereby ligation can occur if the probes are identical to the target DNA. In the oligonucleotide ligase assay, two probes are designed; an allele-specific probe which hybridizes to the target DNA so that its 3' base is situated directly over the SNP nucleotide and a second probe that hybridizes the template upstream (downstream in the complementary strand) of the SNP polymorphic site providing a 5' end for the ligation reaction. If the allele-specific probe matches the target DNA, it will fully hybridize to the target DNA and ligation can occur. Ligation does not generally occur in the presence of a mismatched 3' base. Ligated or unligated products can be detected by gel electrophoresis, MALDI-TOF mass spectrometry or by capillary electrophoresis for large-scale applications | https://en.wikipedia.org/wiki?curid=9007251 |
SNP genotyping With appropriate sequences and tags on the oligonucleotides, high-throughput sequence data can be generated from the ligated products and genotypes determined (Curry et al., 2012). The use of large numbers of sample indexes allows high-throughput sequence data on hundreds of SNPs in thousands of samples to be generated in a small portion of a high-throughput sequencing run. This is a massive genotyping by sequencing technology (MGST). The characteristic DNA properties of melting temperature and single stranded conformation have been used in several applications to distinguish SNP alleles. These methods very often achieve high specificity but require highly optimized conditions to obtain the best possible results. Single-stranded DNA (ssDNA) folds into a tertiary structure. The conformation is sequence dependent and most single base pair mutations will alter the shape of the structure. When applied to a gel, the tertiary shape will determine the mobility of the ssDNA, providing a mechanism to differentiate between SNP alleles. This method first involves PCR amplification of the target DNA. The double-stranded PCR products are denatured using heat and formaldehyde to produce ssDNA. The ssDNA is applied to a non-denaturing electrophoresis gel and allowed to fold into a tertiary structure. Differences in DNA sequence will alter the tertiary conformation and be detected as a difference in the ssDNA strand mobility (Costabile et al. 2006) | https://en.wikipedia.org/wiki?curid=9007251 |
SNP genotyping This method is widely used because it is technically simple, relatively inexpensive and uses commonly available equipment. However compared to other methods, the sensitivity of this assay is lower. It has been found that the ssDNA conformation is highly dependent on temperature and it is not generally apparent what the ideal temperature is. Very often the assay will be carried out using several different temperatures. There is also a restriction on the length of fragment because the sensitivity drops when sequences longer than 400 bp are used (Costabile et al. 2006). The temperature gradient gel electrophoresis (TGGE) or temperature gradient capillary electrophoresis (TGCE) method is based on the principle that partially denatured DNA is more restricted and travels slower in a porous material such as a gel. This property allows for the separation of DNA by melting temperature. To adapt these methods for SNP detection, two fragments are used; the target DNA which contain the SNP polymorphic site being interrogated and an allele-specific DNA sequence, referred to as the normal DNA fragment. The normal fragment is identical to the target DNA except potentially at the SNP polymorphic site, which is unknown in the target DNA. The fragments are denatured and then reannealed. If the target DNA has the same allele as the normal fragment, homoduplexes will form that will have the same melting temperature. When run on the gel with a temperature gradient, only one band will appear | https://en.wikipedia.org/wiki?curid=9007251 |
SNP genotyping If the target DNA has a distinct allele, four products will form following the reannealing step; homoduplexes consisting of target DNA, homoduplexes consisting of normal DNA and two heterduplexes of each strand of target DNA hybridized with the normal DNA strand. These four products will have distinct melting temperatures and will appear as four bands in the denaturing gel. Denaturing high performance liquid chromatography (DHPLC) uses reversed-phase HPLC to interrogate SNPs. The key to DHPLC is the solid phase which has differential affinity for single and double-stranded DNA. In DHPLC, DNA fragments are denatured by heating and then allowed to reanneal. The melting temperature of the reannealed DNA fragments determines the length of time they are retained in the column. Using PCR, two fragments are generated; target DNA containing the SNP polymorphic site and an allele-specific DNA sequence, referred to as the normal DNA fragment. This normal fragment is identical to the target DNA except potentially at the SNP polymorphic site, which is unknown in the target DNA. The fragments are denatured and then allowed to gradually reanneal. The reannaled products are added to the DHPLC column. If the SNP allele in the target DNA matches the normal DNA fragment, only identical homoduplexes will form during the reannealing step | https://en.wikipedia.org/wiki?curid=9007251 |
SNP genotyping If the target DNA contains a different SNP allele than the normal DNA fragment, heteroduplexes of the target DNA and normal DNA containing a mismatched polymorphic site will form in addition to homoduplexes. The mismatched heteroduplexes will have a different melting temperature than the homoduplexes and will not be retained in the column as long. This generates a chromatograph pattern that is distinctive from the pattern that would be generated if the target DNA fragment and normal DNA fragments were identical. The eluted DNA is detected by UV absorption. DHPLC is easily automated as no labeling or purification of the DNA fragments is needed. The method is also relatively fast and has a high specificity. One major drawback of DHPLC is that the column temperature must be optimized for each target in order to achieve the right degree of denaturation. High Resolution Melting analysis is the simplest PCR-based method to understand. Basically, the same thermodynamic properties that allowed for the gel techniques to work apply here, and in real-time. A fluorimeter monitors the post-PCR denaturation of the entire dsDNA amplicon. You make primers specific to the site you want to amplify. You "paint" the amplicon with a double-strand specific dye, included in the PCR mix. The ds-specific dye integrates itself into the PCR product. In essence, the entire amplicon becomes a probe. This opens up new possibilities for discovery | https://en.wikipedia.org/wiki?curid=9007251 |
SNP genotyping Either you position the primers very close to either side of the SNP in question (small amplicon genotyping, Liew, 2004) or amplify a larger region (100-400bp in length) for scanning purposes. For simple genotyping of an SNP, it is easier to just make the amplicon small to minimize the chances you mistake one SNP for another. The melting temperature (Tm) of the entire amplicon is determined and most homozygotes are sufficiently different (in the better instruments) in Tm to genotype. Heterozygotes are even easier to differentiate because they have heteroduplexes generated (refer to the gel-based explanations) which broadens the melt transition and usually gives two discernible peaks. Amplicon melting using a fluorescently-labeled primer has been described (Gundry et al., 2003) but is less practical than using ds-specific dyes due to the cost of the fluorogenic primer. Scanning of larger amplicons is based on the same principles as outlined above. However, melting temperature and the overall shape of the melting curve become informative. For amplicons >c.150bp there are often >2 melting peaks, each of which can vary, depending on the DNA template composition. Numerous investigators have been able to successfully eliminate the majority of their sequencing through melt-based scanning, allowing accurate locus-based genotyping of large numbers of individuals. Many investigators have found scanning for mutations using high resolution melting as a viable and practical way to study entire genes | https://en.wikipedia.org/wiki?curid=9007251 |
SNP genotyping DNA mismatch-binding proteins can distinguish single nucleotide mismatches and thus facilitate differential analysis of SNPs. For example, MutS protein from "Thermus aquaticus" binds different single nucleotide mismatches with different affinities and can be used in capillary electrophoresis to differentiate all six sets of mismatches (Drabovich & Krylov 2006). SNPlex is a proprietary genotyping platform sold by Applied Biosystems. Surveyor nuclease is a mismatch endonuclease enzyme that recognizes all base substitutions and small insertions/deletions (indels), and cleaves the 3′ side of mismatched sites in both DNA strands. Next-generation sequencing technologies such as pyrosequencing sequence less than 250 bases in a read which limits their ability to sequence whole genomes. However, their ability to generate results in real-time and their potential to be massively scaled up makes them a viable option for sequencing small regions to perform SNP genotyping. Compared to other methods, sequencing is in particular, suited to identifying multiple SNPs in a small region, such as the highly polymorphic Major Histocompatibility Complex region of the genome. | https://en.wikipedia.org/wiki?curid=9007251 |
Center of Astronomy (Heidelberg University) The Zentrum für Astronomie der Universität Heidelberg (Center for Astronomy of Heidelberg University) in Heidelberg, Germany, founded in 2005, is an association of three, formerly state-run research institutes: the Astronomisches Rechen-Institut, the Institut für Theoretische Astrophysik (Institute for Theoretical Astrophysics) and the Landessternwarte Heidelberg-Königstuhl (Heidelberg-Königstuhl State Observatory). | https://en.wikipedia.org/wiki?curid=9009428 |
Swazian The is a poorly defined geological stage in South Africa extending from about four billion years ago to 3 billion years ago , encompassing some of the Hadean and much of the Archean on the Geologic time scale. Other scales assign the to parts of the Paleoarchean and Mesoarchean, 3.5 to 2.8 billion years ago. The is not recognized by the International Commission on Stratigraphy nor by the Geological Society of America, the two most widely accepted developers of international geologic time scales. | https://en.wikipedia.org/wiki?curid=9027028 |
Porth (crater) Porth is a crater on the planet Mars. It is named after the town of Porth, Rhondda Cynon Taff, south Wales, United Kingdom. It is located at 21.4°N, 255.9°W and has a diameter of 9.3 kilometers. | https://en.wikipedia.org/wiki?curid=9033245 |
ChaNGa (Charm N-body GrAvity solver) is a computer program to perform collisionless "N"-body simulations. It can perform cosmological simulations with periodic boundary conditions in comoving coordinates or simulations of isolated stellar systems. It is based on the Barnes–Hut algorithm and uses Ewald summation for periodic forces. makes use of the Charm++ parallel programming system, including its dynamic load balancing schemes, in order to scale to large processor configurations. Simulation results have been reported on up to 20,000 IBM Bluegene/L processors . For more information on obtaining, building and running ChaNGa, please see the Wiki documentation at | https://en.wikipedia.org/wiki?curid=9041863 |
Gravit is a free and open-source gravity simulator distributed under the GNU General Public License. The program is available for all major operating systems, including Linux and other Unix-like systems, Microsoft Windows and Mac OS X. uses the Barnes–Hut algorithm to simulate the "n"-body problem. is a gravity simulator which runs under Linux, Windows and Mac OS X. It is released under the GNU General Public License which makes it free. It uses Newtonian physics using the Barnes-Hut N-body algorithm. Although the main goal of is to be as accurate as possible, it also creates beautiful looking gravity patterns. It records the history of each particle so it can animate and display a path of its travels. At any stage you can rotate your view in 3D and zoom in and out. uses OpenGL with Lua, SDL, SDL_ttf and SDL_image. Features As of some time in 2017, the website is dead, though the GitHub repository remains alive. | https://en.wikipedia.org/wiki?curid=9044034 |
Planar deformation features Planar deformation features, or PDFs, are optically recognizable microscopic features in grains of silicate minerals (usually quartz or feldspar), consisting of very narrow planes of glassy material arranged in parallel sets that have distinct orientations with respect to the grain's crystal structure. PDFs are only produced by extreme shock compressions on the scale of meteor impacts. They are not found in volcanic environments. Their presence therefore is a primary criterion for recognizing that an impact event has occurred. | https://en.wikipedia.org/wiki?curid=9051115 |
George Isaak George Richard Isaak (7 March 1933 – 5 June 2005) was a Polish Australian physicist, an important figure in the development of helio- and asteroseismology. Isaak was born in Poland on 7 March 1933. His family moved to Germany after the Second World War and to Australia in 1950. Isaak studied at the University of Melbourne, achieving his Bachelor of Science (BSc) in 1955 and Master of Science (MSc) in 1958. A spell in industry followed, in which Isaak worked for ICI in Australia 1959-1960 during which time he patented a spectrophotometer for very high-resolution optical spectroscopy, using the resonant scattering of light by atoms. In 1961 Isaak returned to science at the University of Birmingham from whom he received his PhD in 1966, and where he stayed until his retirement in 1996, at this time taking up an Adjunct Faculty position at the University of Minnesota. Isaak remained active in scientific endeavors until the time of his death. Isaak married once to Umit, a fellow physicist at Birmingham in 1964. Isaak's work in resonant-scattering spectroscopy observations of the Sun directly led to the first detection (1979) of the Solar five-minute oscillations as a global phenomenon, directly leading to the science of Helioseismology - the study of the solar interior by analysis of the properties of these oscillations. Isaak led the High Resolution Optical Spectroscopy (HiROS) Group at the University of Birmingham, establishing the six-site global BiSON network for helioseismic observations | https://en.wikipedia.org/wiki?curid=9053320 |
George Isaak In many ways ahead of his time, Isaak also devoted efforts to observation of these 'solar like' observations in other stars, a science now known as Asteroseismology. | https://en.wikipedia.org/wiki?curid=9053320 |
Rudolf Felder (2 May 1842 in Vienna – 29 March 1871 in Vienna) was an Austrian jurist and entomologist. He was mainly interested in Lepidoptera, amassing, with his father, Cajetan Felder, a huge collection. | https://en.wikipedia.org/wiki?curid=9054249 |
Clab The Clab, also known as "Centralt mellanlager för använt kärnbränsle" (Swedish for 'Central holding storage for spent nuclear fuel') is an interim radioactive waste repository located about 25 kilometers north of Oskarshamn Nuclear Power Plant and is owned by Oskarshamnsverkets Kraftgrupp AB (OKG), in Oskarshamn. It was opened in 1985 for the storage of spent nuclear fuel from all Swedish nuclear power plants. The fuel is stored for 30 to 40 years, in preparation for final storage. The facility currently contains approximately 6,500 tons of high-level waste, submerged in 8 meters of water, in pools 30 meters below the surface. Contaminated reactor components, such as control rods, are also stored at the facility. Waste produced from Sweden's nuclear power plants will continue be stored at the facility until the Swedish Nuclear Fuel and Waste Management Company can complete construction of a more permanent storage site at Forsmark. | https://en.wikipedia.org/wiki?curid=9054351 |
Puumala orthohantavirus (PUUV) is a species of "Orthohantavirus". Humans infected with the virus may develop a haemorrhagic fever with renal syndrome (HFRS) known as nephropathia epidemica. "Puumala orthohantavirus" HFRS is lethal in less than 0.5% of the cases. Rarely, PUUV infection can cause Guillain-Barré syndrome. "Puumala orthohantavirus" was discovered and named in 1980 named after Puumala, a municipality in Finland. The virus is found predominantly in Scandinavia and Finland, although it has also been reported elsewhere in Northern Europe, Poland and Russia. Because the bank vole ("Myodes glareolus") acts as a reservoir for the virus, nephropathia epidemica cases track with the vole population in a three- to four-year cycle. Humans are infected through inhalation of dust from vole droppings. It has been theorized that "Puumala orthohantavirus", unlike other members of the genus "Orthohantavirus", may also have lethal effects on its rodent host. In August 2014 an Israeli researcher studying the behavior of the bank vole in Finland died after contracting the "Puumala orthohantavirus", which caused a complete breakdown of her immune system. | https://en.wikipedia.org/wiki?curid=9054715 |
Alois Friedrich Rogenhofer (22 December 1831, Vienna – 15 January 1897, Vienna) was an Austrian entomologist. He was a curator at the Naturhistorisches Museum in Vienna, where he was the first keeper of the Lepidoptera. Rogenhofer was mainly interested in Lepidoptera, and Hymenoptera. Beside him Josef Mann (1804-1889) worked as a keen technician and collector for the benefits of the museum. Mann described many species of Lepidoptera new to science focussing on Microlepidoptera. | https://en.wikipedia.org/wiki?curid=9056359 |
Geoforecasting is the science of predicting the movement of tectonic plates and the future climate, shape, and other geological elements of the planet. is particularly important in the siting of depositories for radioactive materials. It also is useful in other areas with long term management issues such as water management. | https://en.wikipedia.org/wiki?curid=9056438 |
Nigel Savery Prof. is Professor of Molecular Biologist at the University of Bristol. During his time researching and lecturing at the University of Bristol, Dr Savery has made significant contributions to the field of transcription and DNA-damage recognition and repair. Understanding how proteins interact with DNA is an important first step to developing novel methods to study genetics. Dr Savery's group has recently made advances in the study of the "E. coli" protein MFD ( a transcription-repair coupling factor, a bacterial protein involved in repair of damaged DNA). | https://en.wikipedia.org/wiki?curid=9059122 |
Yttrium lithium fluoride (LiYF, sometimes abbreviated YLF) is a birefringent crystal, typically doped with neodymium and used as a gain medium in solid-state lasers. | https://en.wikipedia.org/wiki?curid=9065728 |
Peter John Wyllie (born 8 February 1930, in London, England) is a British petrologist and academic. He was Professor of Geology at the California Institute of Technology from 1983 until his retirement in 1999. Prior to this, he held positions at the University of St Andrews (1955–56), Pennsylvania State University (1958–59 and 1961–66), the University of Leeds (1959–61), and the University of Chicago (1965–83). He is well known for his many contributions to the understanding of magmatism, particularly through his work on the experimental petrology of magmas and volatiles. In the early 1970s, Wyllie wrote two widely used textbooks; "The Dynamic Earth" (1971) and "The Way the Earth Works" (1976) which integrated the new understanding of magmatism and plate tectonics. He is also famous for his contributions to the coverage of earth sciences in the "Encyclopædia Britannica", particularly his outline of the field in Part Two of the "Propædia". Wylie was President of the International Union of Geodesy and Geophysics (IUGG) from 1995 to 1999. | https://en.wikipedia.org/wiki?curid=9076272 |
Buckley–Leverett equation In fluid dynamics, the is a conservation equation used to model two-phase flow in porous media. The or the Buckley–Leverett "displacement" describes an immiscible displacement process, such as the displacement of oil by water, in a one-dimensional or quasi-one-dimensional reservoir. This equation can be derived from the mass conservation equations of two-phase flow, under the assumptions listed below. In a quasi-1D domain, the is given by: where formula_2 is the wetting-phase (water) saturation, formula_3 is the total flow rate, formula_4 is the rock porosity, formula_5 is the area of the cross-section in the sample volume, and formula_6 is the fractional flow function of the wetting phase. Typically, formula_6 is an 'S'-shaped, nonlinear function of the saturation formula_8, which characterizes the relative mobilities of the two phases: where formula_10 and formula_11 denote the wetting and non-wetting phase mobilities. formula_12 and formula_13 denote the relative permeability functions of each phase and formula_14 and formula_15 represent the phase viscosities. The is derived based on the following assumptions: The characteristic velocity of the is given by: The hyperbolic nature of the equation implies that the solution of the has the form formula_17, where formula_18 is the characteristic velocity given above. The non-convexity of the fractional flow function formula_6 also gives rise to the well known Buckley-Leverett profile, which consists of a shock wave immediately followed by a rarefaction wave. | https://en.wikipedia.org/wiki?curid=9089819 |
Antagonism (chemistry) Chemical antagonists impede the normal function of a system. They function to invert the effects of other molecules. The effects of antagonists can be seen after they have encountered an agonist, and as a result, the effects of the agonist is neutralized. Antagonists such as dopamine antagonist slow down movement in lab rats. Although they hinder the joining of enzymes to substrates, Antagonists can be beneficial. For example, not only do angiotensin receptor blockers, and angiotensin-converting enzyme (ACE) inhibitors work to lower blood pressure, but they also counter the effects of renal disease in diabetic and non-diabetic patients. Chelating agents, such as calcium di sodium defeated, fall into the category of antagonists and operate to minimize the lethal effects of heavy metals such as mercury or lead. In chemistry, antagonism is a phenomenon wherein two or more agents in combination have an overall effect that is less than the sum of their individual effects. The word is most commonly used in this context in biochemistry and toxicology: interference in the physiological action of a chemical substance by another having a similar structure. For instance, a receptor antagonist is an agent that reduces the response that a ligand produces when the receptor antagonist binds to a receptor on a cell. An example of this is the interleukin-1 receptor antagonist. The opposite of antagonism is synergy. It is a negative type of synergism | https://en.wikipedia.org/wiki?curid=9095203 |
Antagonism (chemistry) Experiments with different combinations show that binary mixtures of phenolics can lead to either a synergetic antioxidant effect or to an antagonistic effect. | https://en.wikipedia.org/wiki?curid=9095203 |
New England Biolabs (NEB) produces and supplies recombinant and native enzyme reagents for the life science research, as well as providing solutions supporting genome editing, synthetic biology and next-generation sequencing. NEB also provides free access to research tools such as REBASE, InBASE, and Polbase. The company was established in 1974 by Donald Comb as a cooperative laboratory of experienced scientists and initially produced restriction enzymes on a commercial scale. The company then began producing solution-oriented products. It received approximately $1.7 million in Small Business Innovation Research (SBIR) grants between 2009 and 2013 for this research. NEB produces 230 recombinant and 30 native restriction enzymes for genomic research, as well as nicking enzymes and DNA methylases. It pursues research in areas related to proteomics, DNA Sequencing, and drug discovery. NEB scientists also conduct basic research in Molecular Biology and Parasitology. The company has subsidiaries in Singapore, Canada, China, France, Germany, Japan, the U.K., and Australia, and distributors in South America, Australia, and other countries in Europe and Asia. Its headquarters are in Ipswich, MA. Development of the current headquarters began in 2000, and was completed in 2005. Donald Comb served as the company's Chairman and CEO from the company's founding in 1974, until 2005. In 2005, he was replaced as chief executive by James Ellard, though Comb remained Chairman. NEB employs over 450 people at its headquarters | https://en.wikipedia.org/wiki?curid=9096236 |
New England Biolabs As company policy, all scientists and some executives must work at least one day per month on the customer support telephone line, answering technical support questions about the company's products. Sir Richard John Roberts is the company's Chief Scientific Officer. He shared the 1993 Nobel Prize in Physiology or Medicine with Phillip Allen Sharp for the discovery of introns in eukaryotic DNA and the mechanism of gene-splicing. In 2015, NEB committed to establishing a GMP manufacturing facility near its headquarters in Ipswich, Massachusetts, and the 40,000-sq-ft facility was completed in 2018. The multi-product Rowley Cleanroom Manufacturing Facility makes GMP-grade products and has a 10,000-sq-ft mechanical mezzanine. In January 2017, NEB released Luna universal quantitative real-time polymerase chain reaction (qPCR) and reverse-transcription quantitative polymerase chain reaction (RT-qPCR) kits. The Luna kits are used for DNA or RNA quantitation. In December 2017, the company released the NEBNext Ultra II FS DNA library prep kit for next-generation sequencing (NGS). In October 2019, NEB released a new RNA depletion product, the NEBNext Globin & rRNA Depletion Kit (Human/Mouse/Rat) and NEBNext rRNA Depletion Kit (Bacteria). The kits offer specific depletion of the RNA species that interfere with the analysis of coding and non-coding RNAs. That same month, the company announced its NEBNext Direct Genotyping Solution | https://en.wikipedia.org/wiki?curid=9096236 |
New England Biolabs The product delivers a one day, automatable genotyping workflow for a variety of applications in Agricultural biotechnology. In January 2020, NEB signed an agreement with ERS Genomics Limited that gave NEB rights to sell CRISPR/Cas9 tools and reagents, used for gene editing. developed a colorimetric loop-mediated isothermal amplification (LAMP) assay for research use. This assay can be used to test for the presence of virus through nucleic acid detection, returning results in only 30 minutes. In 2020, the LAMP method was one of several molecular tests used to detect RNA from SARS-CoV-2, a strain of coronavirus that causes COVID-19. In February, NEB worked with the Wuhan Institute of Virology and the Chinese Academy of Sciences to test a method of identifying SARS-CoV-2 virus. The company runs free scientific databases. REBASE, the restriction enzyme database, contains the details of commercial and research endonucleases. In 2011 the company founded Polbase, an online database which provides information specifically about polymerases. Another free NEB database is InBase, an intein database, which includes the Intein Registry and information about each intein. In 2001, NEB co-founded the marine DNA library Ocean Genome Legacy (OGL), which according to the "Boston Globe", “catalogues samples of organisms from all over the world, to be made available to scientists for research”. Though originally located on the NEB campus, OGLF relocated to the Nahant campus of Northeastern University in 2014 | https://en.wikipedia.org/wiki?curid=9096236 |
New England Biolabs To enable point-of-use sales of its reagents, NEB created a digital interface for enzyme-housing freezers to be used at customer storage sites, through a partnership with Ionia Corp. and Salesforce.com. The data is used by the company for both sales logistics and as a part of future enzyme research development. It has also partnered with Harvard University on recycling and reclamation initiatives when its products and packaging come to the end of their use or lifecycle. , NEB also had a distribution agreement with VWR. In June 2019, NEB, Waters, and Genos announced they would work together on The Human Glycome Project, a global initiative to map the structure and function of human glycans. NEB will supply a version of its Rapid PNGase F technology to aid in increased sample preparation and improve process throughput. That same month, NEB entered a partnership with Bioz, Inc., an artificial intelligence technology company, to provide its customers with access to examples of real-world applications of its products. | https://en.wikipedia.org/wiki?curid=9096236 |
Jean de Heinzelin de Braucourt (6 August 1920 – 4 November 1998) was a Belgian geologist who worked mainly in Africa. He worked at the universities of Ghent and Brussels. He gained international fame in 1960 when he discovered the Ishango Bone. | https://en.wikipedia.org/wiki?curid=9098327 |
Leverett J-function In petroleum engineering, the Leverett "J"-function is a dimensionless function of water saturation describing the capillary pressure, where formula_2 is the water saturation measured as a fraction, formula_3 is the capillary pressure (in pascal), formula_4 is the permeability (measured in m²), formula_5 is the porosity (0-1), formula_6 is the surface tension (in N/m) and formula_7 is the contact angle. The function is important in that it is constant for a given saturation within a reservoir, thus relating reservoir properties for neighboring beds. The Leverett "J"-function is an attempt at extrapolating capillary pressure data for a given rock to rocks that are similar but with differing permeability, porosity and wetting properties. It assumes that the porous rock can be modelled as a bundle of non-connecting capillary tubes, where the factor formula_8 is a characteristic length of the capillaries' radii. This function is also widely used in modeling two-phase flow of proton-exchange membrane fuel cells. A large degree of hydration is needed for good proton conductivity while large liquid water saturation in pores of catalyst layer or diffusion media will impede gas transport in the cathode. | https://en.wikipedia.org/wiki?curid=9105584 |
Biology is the natural science that studies life and living organisms, including their physical structure, chemical processes, molecular interactions, physiological mechanisms, development and evolution. Despite the complexity of the science, there are certain unifying concepts that consolidate it into a single, coherent field. recognizes the cell as the basic unit of life, genes as the basic unit of heredity, and evolution as the engine that propels the creation and extinction of species. Living organisms are open systems that survive by transforming energy and decreasing their local entropy to maintain a stable and vital condition defined as homeostasis. Sub-disciplines of biology are defined by the research methods employed and the kind of system studied: theoretical biology uses mathematical methods to formulate quantitative models while experimental biology performs empirical experiments to test the validity of proposed theories and understand the mechanisms underlying life and how it appeared and evolved from non-living matter about 4 billion years ago through a gradual increase in the complexity of the system. See branches of biology. derives from the Ancient Greek words of βίος; romanized bíos meaning "life" and -λογία; romanized logía (-logy) meaning "branch of study" or "to speak". Those combined make the Greek word βιολογία; romanized biología meaning biology. Despite this, the term βιολογία as a whole didn't exist in Ancient Greek. The first to borrow it was the English and French ("biologie") | https://en.wikipedia.org/wiki?curid=9127632 |
Biology Since the advent of the scientific era, reanalyzable as a compound using the combining forms bio + logy. The term "biology" is derived from the Greek word , "vios", "life" and the suffix , "-logia", "study of." The Latin-language form of the term first appeared in 1736 when Swedish scientist Carl Linnaeus (Carl von Linné) used "biologi" in his "Bibliotheca Botanica". It was used again in 1766 in a work entitled "Philosophiae naturalis sive physicae: tomus III, continens geologian, biologian, phytologian generalis", by Michael Christoph Hanov, a disciple of Christian Wolff. The first German use, "Biologie", was in a 1771 translation of Linnaeus' work. In 1797, Theodor Georg August Roose used the term in the preface of a book, "Grundzüge der Lehre van der Lebenskraft". Karl Friedrich Burdach used the term in 1800 in a more restricted sense of the study of human beings from a morphological, physiological and psychological perspective ("Propädeutik zum Studien der gesammten Heilkunst"). The term came into its modern usage with the six-volume treatise "Biologie, oder Philosophie der lebenden Natur" (1802–22) by Gottfried Reinhold Treviranus, who announced: Although modern biology is a relatively recent development, sciences related to and included within it have been studied since ancient times. Natural philosophy was studied as early as the ancient civilizations of Mesopotamia, Egypt, the Indian subcontinent, and China | https://en.wikipedia.org/wiki?curid=9127632 |
Biology However, the origins of modern biology and its approach to the study of nature are most often traced back to ancient Greece. While the formal study of medicine dates back to Pharaonic Egypt, it was Aristotle (384–322 BC) who contributed most extensively to the development of biology. Especially important are his "History of Animals" and other works where he showed naturalist leanings, and later more empirical works that focused on biological causation and the diversity of life. Aristotle's successor at the Lyceum, Theophrastus, wrote a series of books on botany that survived as the most important contribution of antiquity to the plant sciences, even into the Middle Ages. Scholars of the medieval Islamic world who wrote on biology included al-Jahiz (781–869), Al-Dīnawarī (828–896), who wrote on botany, and Rhazes (865–925) who wrote on anatomy and physiology. Medicine was especially well studied by Islamic scholars working in Greek philosopher traditions, while natural history drew heavily on Aristotelian thought, especially in upholding a fixed hierarchy of life. began to quickly develop and grow with Anton van Leeuwenhoek's dramatic improvement of the microscope. It was then that scholars discovered spermatozoa, bacteria, infusoria and the diversity of microscopic life. Investigations by Jan Swammerdam led to new interest in entomology and helped to develop the basic techniques of microscopic dissection and staining. Advances in microscopy also had a profound impact on biological thinking | https://en.wikipedia.org/wiki?curid=9127632 |
Biology In the early 19th century, a number of biologists pointed to the central importance of the cell. Then, in 1838, Schleiden and Schwann began promoting the now universal ideas that (1) the basic unit of organisms is the cell and (2) that individual cells have all the characteristics of life, although they opposed the idea that (3) all cells come from the division of other cells. Thanks to the work of Robert Remak and Rudolf Virchow, however, by the 1860s most biologists accepted all three tenets of what came to be known as cell theory. Meanwhile, taxonomy and classification became the focus of natural historians. Carl Linnaeus published a basic taxonomy for the natural world in 1735 (variations of which have been in use ever since), and in the 1750s introduced scientific names for all his species. Georges-Louis Leclerc, Comte de Buffon, treated species as artificial categories and living forms as malleable—even suggesting the possibility of common descent. Although he was opposed to evolution, Buffon is a key figure in the history of evolutionary thought; his work influenced the evolutionary theories of both Lamarck and Darwin. Serious evolutionary thinking originated with the works of Jean-Baptiste Lamarck, who was the first to present a coherent theory of evolution | https://en.wikipedia.org/wiki?curid=9127632 |
Biology He posited that evolution was the result of environmental stress on properties of animals, meaning that the more frequently and rigorously an organ was used, the more complex and efficient it would become, thus adapting the animal to its environment. Lamarck believed that these acquired traits could then be passed on to the animal's offspring, who would further develop and perfect them. However, it was the British naturalist Charles Darwin, combining the biogeographical approach of Humboldt, the uniformitarian geology of Lyell, Malthus's writings on population growth, and his own morphological expertise and extensive natural observations, who forged a more successful evolutionary theory based on natural selection; similar reasoning and evidence led Alfred Russel Wallace to independently reach the same conclusions. Although it was the subject of controversy (which continues to this day), Darwin's theory quickly spread through the scientific community and soon became a central axiom of the rapidly developing science of biology. The discovery of the physical representation of heredity came along with evolutionary principles and population genetics. In the 1940s and early 1950s, experiments pointed to DNA as the component of chromosomes that held the trait-carrying units that had become known as genes. A focus on new kinds of model organisms such as viruses and bacteria, along with the discovery of the double-helical structure of DNA in 1953, marked the transition to the era of molecular genetics | https://en.wikipedia.org/wiki?curid=9127632 |
Biology From the 1950s to the present times, biology has been vastly extended in the molecular domain. The genetic code was cracked by Har Gobind Khorana, Robert W. Holley and Marshall Warren Nirenberg after DNA was understood to contain codons. Finally, the Human Genome Project was launched in 1990 with the goal of mapping the general human genome. This project was essentially completed in 2003, with further analysis still being published. The Human Genome Project was the first step in a globalized effort to incorporate accumulated knowledge of biology into a functional, molecular definition of the human body and the bodies of other organisms. Cell theory states that the cell is the fundamental unit of life, that all living things are composed of one or more cells, and that all cells arise from pre-existing cells through cell division. In multicellular organisms, every cell in the organism's body derives ultimately from a single cell in a fertilized egg. The cell is also considered to be the basic unit in many pathological processes. In addition, the phenomenon of energy flow occurs in cells in processes that are part of the function known as metabolism. Finally, cells contain hereditary information (DNA), which is passed from cell to cell during cell division. Research into the origin of life, abiogenesis, amounts to an attempt to discover the origin of the first cells. A central organizing concept in biology is that life changes and develops through evolution, and that all life-forms known have a common origin | https://en.wikipedia.org/wiki?curid=9127632 |
Biology The theory of evolution postulates that all organisms on the Earth, both living and extinct, have descended from a common ancestor or an ancestral gene pool. This universal common ancestor of all organisms is believed to have appeared about 3.5 billion years ago. Biologists regard the ubiquity of the genetic code as definitive evidence in favor of the theory of universal common descent for all bacteria, archaea, and eukaryotes (see: origin of life). The term "evolution" was introduced into the scientific lexicon by Jean-Baptiste de Lamarck in 1809, and fifty years later Charles Darwin posited a scientific model of natural selection as evolution's driving force. (Alfred Russel Wallace is recognized as the co-discoverer of this concept as he helped research and experiment with the concept of evolution.) Evolution is now used to explain the great variations of life found on Earth. Darwin theorized that species flourish or die when subjected to the processes of natural selection or selective breeding. Genetic drift was embraced as an additional mechanism of evolutionary development in the modern synthesis of the theory. The evolutionary history of the species—which describes the characteristics of the various species from which it descended—together with its genealogical relationship to every other species is known as its phylogeny. Widely varied approaches to biology generate information about phylogeny | https://en.wikipedia.org/wiki?curid=9127632 |
Biology These include the comparisons of DNA sequences, a product of molecular biology (more particularly genomics), and comparisons of fossils or other records of ancient organisms, a product of paleontology. Biologists organize and analyze evolutionary relationships through various methods, including phylogenetics, phenetics, and cladistics. (For a summary of major events in the evolution of life as currently understood by biologists, see evolutionary timeline.) Evolution is relevant to the understanding of the natural history of life forms and to the understanding of the organization of current life forms. But, those organizations can only be understood in light of how they came to be by way of the process of evolution. Consequently, evolution is central to all fields of biology. Genes are the primary units of inheritance in all organisms. A gene is a unit of heredity and corresponds to a region of DNA that influences the form or function of an organism in specific ways. All organisms, from bacteria to animals, share the same basic machinery that copies and translates DNA into proteins. Cells transcribe a DNA gene into an RNA version of the gene, and a ribosome then translates the RNA into a sequence of amino acids known as a protein. The translation code from RNA codon to amino acid is the same for most organisms. For example, a sequence of DNA that codes for insulin in humans also codes for insulin when inserted into other organisms, such as plants | https://en.wikipedia.org/wiki?curid=9127632 |
Biology DNA is found as linear chromosomes in eukaryotes, and circular chromosomes in prokaryotes. A chromosome is an organized structure consisting of DNA and histones. The set of chromosomes in a cell and any other hereditary information found in the mitochondria, chloroplasts, or other locations is collectively known as a cell's genome. In eukaryotes, genomic DNA is localized in the cell nucleus, or with small amounts in mitochondria and chloroplasts. In prokaryotes, the DNA is held within an irregularly shaped body in the cytoplasm called the nucleoid. The genetic information in a genome is held within genes, and the complete assemblage of this information in an organism is called its genotype. Homeostasis is the ability of an open system to regulate its internal environment to maintain stable conditions by means of multiple dynamic equilibrium adjustments that are controlled by interrelated regulation mechanisms. All living organisms, whether unicellular or multicellular, exhibit homeostasis. To maintain dynamic equilibrium and effectively carry out certain functions, a system must detect and respond to perturbations. After the detection of a perturbation, a biological system normally responds through negative feedback that stabilize conditions by reducing or increasing the activity of an organ or system. One example is the release of glucagon when sugar levels are too low. The survival of a living organism depends on the continuous input of energy | https://en.wikipedia.org/wiki?curid=9127632 |
Biology Chemical reactions that are responsible for its structure and function are tuned to extract energy from substances that act as its food and transform them to help form new cells and sustain them. In this process, molecules of chemical substances that constitute food play two roles; first, they contain energy that can be transformed and reused in that organism's biological, chemical reactions; second, food can be transformed into new molecular structures (biomolecules) that are of use to that organism. The organisms responsible for the introduction of energy into an ecosystem are known as producers or autotrophs. Nearly all such organisms originally draw their energy from the sun. Plants and other phototrophs use solar energy via a process known as photosynthesis to convert raw materials into organic molecules, such as ATP, whose bonds can be broken to release energy. A few ecosystems, however, depend entirely on energy extracted by chemotrophs from methane, sulfides, or other non-luminal energy sources. Some of the energy thus captured produces biomass and energy that is available for growth and development of other life forms. The majority of the rest of this biomass and energy are lost as waste molecules and heat. The most important processes for converting the energy trapped in chemical substances into energy useful to sustain life are metabolism and cellular respiration. Molecular biology is the study of biology at the molecular level | https://en.wikipedia.org/wiki?curid=9127632 |
Biology This field overlaps with other areas of biology, particularly those of genetics and biochemistry. Molecular biology is a study of the interactions of the various systems within a cell, including the interrelationships of DNA, RNA, and protein synthesis and how those interactions are regulated. The next larger scale, cell biology, studies the structural and physiological properties of cells, including their internal behavior, interactions with other cells, and with their environment. This is done on both the microscopic and molecular levels, for unicellular organisms such as bacteria, as well as the specialized cells of multicellular organisms such as humans. Understanding the structure and function of cells is fundamental to all of the biological sciences. The similarities and differences between cell types are particularly relevant to molecular biology. Anatomy is a treatment of the macroscopic forms of such structures organs and organ systems. Genetics is the science of genes, heredity, and the variation of organisms. Genes encode the information needed by cells for the synthesis of proteins, which in turn play a central role in influencing the final phenotype of the organism. Genetics provides research tools used in the investigation of the function of a particular gene, or the analysis of genetic interactions. Within organisms, genetic information is physically represented as chromosomes, within which it is represented by a particular sequence of amino acids in particular DNA molecules | https://en.wikipedia.org/wiki?curid=9127632 |
Biology Developmental biology studies the process by which organisms grow and develop. Developmental biology, originated from embryology, studies the genetic control of cell growth, cellular differentiation, and "cellular morphogenesis," which is the process that progressively gives rise to tissues, organs, and anatomy. Model organisms for developmental biology include the round worm "Caenorhabditis elegans," the fruit fly "Drosophila melanogaster," the zebrafish "Danio rerio," the mouse "Mus musculus", and the weed "Arabidopsis thaliana". (A model organism is a species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in that organism provide insight into the workings of other organisms.) Physiology is the study of the mechanical, physical, and biochemical processes of living organisms function as a whole. The theme of "structure to function" is central to biology. Physiological studies have traditionally been divided into plant physiology and animal physiology, but some principles of physiology are universal, no matter what particular organism is being studied. For example, what is learned about the physiology of yeast cells can also apply to human cells. The field of animal physiology extends the tools and methods of human physiology to non-human species. Plant physiology borrows techniques from both research fields | https://en.wikipedia.org/wiki?curid=9127632 |
Biology Physiology is the study the interaction of how, for example, the nervous, immune, endocrine, respiratory, and circulatory systems, function and interact. The study of these systems is shared with such medically oriented disciplines as neurology and immunology. Evolutionary research is concerned with the origin and descent of species, and their change over time. It employs scientists from many taxonomically oriented disciplines, for example, those with special training in particular organisms such as mammalogy, ornithology, botany, or herpetology, but are of use in answering more general questions about evolution. Evolutionary biology is partly based on paleontology, which uses the fossil record to answer questions about the mode and tempo of evolution, and partly on the developments in areas such as population genetics. In the 1980s, developmental biology re-entered evolutionary biology after its initial exclusion from the modern synthesis through the study of evolutionary developmental biology. Phylogenetics, systematics, and taxonomy are related fields often considered part of evolutionary biology. Multiple speciation events create a tree structured system of relationships between species. The role of systematics is to study these relationships and thus the differences and similarities between species and groups of species. However, systematics was an active field of research long before evolutionary thinking was common | https://en.wikipedia.org/wiki?curid=9127632 |
Biology Traditionally, living things have been divided into five kingdoms: Monera; Protista; Fungi; Plantae; Animalia. However, many scientists now consider this five-kingdom system outdated. Modern alternative classification systems generally begin with the three-domain system: Archaea (originally Archaebacteria); Bacteria (originally Eubacteria) and Eukaryota (including protists, fungi, plants, and animals). These domains reflect whether the cells have nuclei or not, as well as differences in the chemical composition of key biomolecules such as ribosomes. Further, each kingdom is broken down recursively until each species is separately classified. The order is: Domain; Kingdom; Phylum; Class; Order; Family; Genus; Species. Outside of these categories, there are obligate intracellular parasites that are "on the edge of life" in terms of metabolic activity, meaning that many scientists do not actually classify such structures as alive, due to their lack of at least one or more of the fundamental functions or characteristics that define life. They are classified as viruses, viroids, prions, or satellites. The scientific name of an organism is generated from its genus and species. For example, humans are listed as "Homo sapiens". "Homo" is the genus, and "sapiens" the species. When writing the scientific name of an organism, it is proper to capitalize the first letter in the genus and put all of the species in lowercase. Additionally, the entire term may be italicized or underlined | https://en.wikipedia.org/wiki?curid=9127632 |
Biology The dominant classification system is called the Linnaean taxonomy. It includes ranks and binomial nomenclature. How organisms are named is governed by international agreements such as the International Code of Nomenclature for algae, fungi, and plants (ICN), the International Code of Zoological Nomenclature (ICZN), and the International Code of Nomenclature of Bacteria (ICNB). The classification of viruses, viroids, prions, and all other sub-viral agents that demonstrate biological characteristics is conducted by the International Committee on Taxonomy of Viruses (ICTV) and is known as the International Code of Viral Classification and Nomenclature (ICVCN). However, several other viral classification systems do exist. A merging draft, BioCode, was published in 1997 in an attempt to standardize nomenclature in these three areas, but has yet to be formally adopted. The BioCode draft has received little attention since 1997; its originally planned implementation date of January 1, 2000, has passed unnoticed. A revised BioCode that, instead of replacing the existing codes, would provide a unified context for them, was proposed in 2011. However, the International Botanical Congress of 2011 declined to consider the BioCode proposal. The ICVCN remains outside the BioCode, which does not include viral classification. Ecology is the study of the distribution and abundance of living organisms, the interaction between them and their environment | https://en.wikipedia.org/wiki?curid=9127632 |
Biology An organism shares an environment that includes other organisms and biotic factors as well as local abiotic factors (non-living) such as climate and ecology. One reason that biological systems can be difficult to study is that so many different interactions with other organisms and the environment are possible, even on small scales. A microscopic bacterium responding to a local sugar gradient is responding to its environment as much as a lion searching for food in the African savanna. For any species, behaviors can be co-operative, competitive, parasitic, or symbiotic. Matters become more complex when two or more species interact in an ecosystem. Ecological systems are studied at several different levels, from the scale of the ecology of individual organisms, to those of populations, to the ecosystems and finally the biosphere. The term population biology is often used interchangeably with population ecology, although "population biology" is more frequently used in the case of diseases, viruses, and microbes, while the term population ecology is more commonly applied to the study of plants and animals. Ecology draws on many subdisciplines. Ethology is the study of animal behavior (particularly that of social animals such as primates and canids), and is sometimes considered a branch of zoology. Ethologists have been particularly concerned with the evolution of behavior and the understanding of behavior in terms of the theory of natural selection | https://en.wikipedia.org/wiki?curid=9127632 |
Biology In one sense, the first modern ethologist was Charles Darwin, whose book, "The Expression of the Emotions in Man and Animals," influenced many ethologists to come. Biogeography studies the spatial distribution of organisms on the Earth, focusing on such topics as plate tectonics, climate change, dispersal and migration, and cladistics. Despite the profound advances made over recent decades in our understanding of life's fundamental processes, some basic problems have remained unresolved. Some examples are Origin of life. While there is very good evidence for the abiotic origin of biological compounds such as amino acids, nucleotides and lipids, it is largely unclear how these molecules came together to form the first cells. Related is the question of extra-terrestrial life. If we understand how life originated on earth, we can predict more reliably which conditions are required to generate life on other planets. Aging. At present, there is no consensus view on the underlying cause of aging. Various competing theories are outlined in Ageing Theories. Pattern formation. We have a good understanding of pattern formation in some systems, such as the early insect embryo, but the generation of many patterns in nature cannot be explained easily, e.g. the stripes in zebras or many snakes, such as coral snakes. While we know that the patterns are generated by selective activation or repression of genes, many of these genes and their regulatory mechanisms remain unknown | https://en.wikipedia.org/wiki?curid=9127632 |
Biology is an area of science with numerous subdisciplines that are concerned with all aspects of life, in fact all aspects of modern human life. That said, there are countless career options, ranging from basic science to industrial or agricultural applications. These are the main branches of biology: | https://en.wikipedia.org/wiki?curid=9127632 |
Lopolith A lopolith is a large igneous intrusion which is lenticular in shape with a depressed central region. Lopoliths are generally concordant with the intruded strata with dike or funnel-shaped feeder bodies below the body. The term was first defined and used by Frank Fitch Grout during the early 1900s in describing the Duluth gabbro complex in northern Minnesota and adjacent Ontario. Lopoliths typically consist of large layered intrusions that range in age from Archean to Eocene. Examples include the Duluth gabbro, the Sudbury Igneous Complex of Ontario, the Bushveld igneous complex of South Africa, the Great Dyke in Zimbabwe, the Skaergaard complex of Greenland and the Humboldt lopolith of Nevada. The Sudbury occurrence has been attributed to an impact event and associated crustal melting. | https://en.wikipedia.org/wiki?curid=9137006 |
Dopplergraph A dopplergraph (dopplergram) is a two dimensional representation of the approaching and receding motions of an object or area. The word dopplergraph is a combination of the words doppler and photograph. Dopplergraphs are two-dimensional records of variations in the doppler shift in light intensity. Dopplergraphs do not need to be a record of the shift of visible light, but of any radiated wave, which includes electromagnetic waves and acoustic waves. Because the doppler shift is caused by the velocity of the radiating source towards or away from the viewer, a dopplergraph is a picture of the velocities associated with the sources being viewed. | https://en.wikipedia.org/wiki?curid=9144140 |
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