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Hypothetical list of biota A hypothetical list of biota, or "hypothetical list" for short, is a list of taxa (of plants, animals, fungi etc.) which are not recorded from a given geographical area, but which "may" be found there. Such lists are sometimes included by authors of regional biota, partly to demonstrate that the authors have considered and rejected the taxa in question rather than overlooked them, and partly to encourage researchers and others to seek out the taxa in question so that they can be added to the list of the area's biota in future revisions. Taxa may be included for different reasons: A 1973 checklist of fleas in Connecticut added species to its hypothetical list if they were documented in a bordering state and have a host found in Connecticut. Ornithological works which have included hypothetical lists include the following: | https://en.wikipedia.org/wiki?curid=9146657 |
Malaia garnet or Malaya garnet is a gemological varietal name for light to dark slightly pinkish orange, reddish orange, or yellowish orange garnet, that are of a mixture within the "pyralspite" series pyrope, almandine, and spessartine with a little calcium. The name Malaia is translated from Swahili to mean, "one coming from Malay archipelago". It is found in east Africa, in the Umba Valley bordering Tanzania and Kenya. | https://en.wikipedia.org/wiki?curid=9150392 |
Odd number theorem The odd number theorem is a theorem in strong gravitational lensing which comes directly from differential topology. The theorem states that "the number of multiple images produced by a bounded transparent lens must be odd". The gravitational lensing is a thought to mapped from what's known as "image plane" to "source plane" following the formula : formula_1. If we use direction cosines describing the bent light rays, we can write a vector field on formula_2 plane formula_3. However, only in some specific directions formula_4, will the bent light rays reach the observer, i.e., the images only form where formula_5. Then we can directly apply the Poincaré–Hopf theorem formula_6. The index of sources and sinks is +1, and that of saddle points is −1. So the Euler characteristic equals the difference between the number of positive indices formula_7 and the number of negative indices formula_8. For the far field case, there is only one image, i.e., formula_9. So the total number of images is formula_10, i.e., odd. The strict proof needs Uhlenbeck's Morse theory of null geodesics. | https://en.wikipedia.org/wiki?curid=9156022 |
Jerry March Jerry March, Ph.D. (August 1, 1929 – December 25, 1997) was an American organic chemist and a professor of chemistry at Adelphi University. March authored the "March's Advanced Organic Chemistry" text, which is considered to be a pillar of graduate-level organic chemistry texts. The book was prepared in its fifth edition at the time of his death. | https://en.wikipedia.org/wiki?curid=9162613 |
Banned substance may refer to: | https://en.wikipedia.org/wiki?curid=9171938 |
Prandtl–Meyer function In aerodynamics, the describes the angle through which a flow turns isentropically from sonic velocity (M=1) to a Mach (M) number greater than 1. The maximum angle through which a sonic ("M" = 1) flow can be turned around a convex corner is calculated for M = formula_1. For an ideal gas, it is expressed as follows, where formula_3 is the Prandtl–Meyer function, formula_4 is the Mach number of the flow and formula_5 is the ratio of the specific heat capacities. By convention, the constant of integration is selected such that formula_6 As Mach number varies from 1 to formula_1, formula_3 takes values from 0 to formula_9, where where, formula_11 is the absolute value of the angle through which the flow turns, formula_4 is the flow Mach number and the suffixes "1" and "2" denote the initial and final conditions respectively. | https://en.wikipedia.org/wiki?curid=9175375 |
Richard P.A.C. Newman (1955–2000) was a physicist notable for his work in the area of cosmology and general relativity. He completed his PhD in 1979 at the University of Kent at Canterbury under G.C. McVittie with a thesis entitled "Singular Perturbations of the Empty Robertson-Walker Cosmologies." He was a research fellow at the University of York 1984-1986. He died 2000. | https://en.wikipedia.org/wiki?curid=9198927 |
List of British county and local bryophyte floras The following is a list of published bryophyte floras covering counties or other local areas of Britain, together with a list of vascular plant floras which also contain bryophyte lists. | https://en.wikipedia.org/wiki?curid=9210489 |
Curt Eisner (April 28, 1890 in Zabrze – December 30, 1981 in The Hague) was a German entomologist who specialised in snow butterflies or Parnassinae. His collections of Parnassinae are in Naturalis, in Leiden, and his Ornithoptera and Morphidae are in the Museum für Naturkunde in Berlin. | https://en.wikipedia.org/wiki?curid=9223758 |
Steve Van Dyck Dr. is the Senior Curator of vertebrates at Queensland Museum, in Brisbane, Queensland, Australia. was instrumental in the rediscovery of the endangered mahogany glider in 1989. has been awarded the 2008 Queensland Museum Medal for Research. Van Dyck was awarded the medal for his considerable talent in discovering a number of new species and also for behavioural studies of Australian mammals. The medal was presented to Dr by the Queensland Arts Minister Rod Welford in February, 2008. Steve Van Dyck's professional publications include: | https://en.wikipedia.org/wiki?curid=9225460 |
Visual MODFLOW (VMOD) is a software program developed by Waterloo Hydrogeologic. Originally released in 1994, was the first commercially available graphical interface for the open source groundwater modeling engine called MODFLOW. As of May 2012, a newer .NET version of the software was rebranded as Flex. The program also combines proprietary extensions, such as MODFLOW-SURFACT, MT3DMS (mass-transport 3D multi-species) and a three-dimensional model explorer. supports MODFLOW-2000, MODFLOW-2005, MODFLOW-NWT, MODFLOW-LGR, MODFLOW-SURFACT, and SEAWAT. The software is used primarily by hydrogeologists to simulate groundwater flow and contaminant transport. The original version of was first released in August 1994, and was developed for DOS by Nilson Guiguer, Thomas Franz and Bob Cleary. It was based on the USGS MODFLOW-88 and MODPATH codes, and resembled the FLOWPATH program that was also developed by Waterloo Hydrogeologic Inc. The first Windows based version was released in 1997 and the main programmers were Sergei Schmakov, Alexander Liftshits, and Sean Wilson. A .NET version that included non-grid-based, graphical conceptual modelling features was released in 2012. On January 10, 2005, Waterloo Hydrogeologic was acquired by Schlumberger's Water Services Technology Group. On May 1, 2012, Waterloo Hydrogeologic released its next generation of called Flex. On March 13, 2015, Waterloo Hydrogeologic was acquired by Nova Metrix. | https://en.wikipedia.org/wiki?curid=9241978 |
Franco-British Nuclear Forum The first meeting of the Franco–British Nuclear Forum was held in Paris in November 2007, chaired by the Minister for Energy and the French Industry Minister. The working groups are focusing on specific areas for collaboration. A follow-up meeting on the issue in London was planned for March 2008, but did not take place. | https://en.wikipedia.org/wiki?curid=9247154 |
Selective adsorption is the effect when minima associated with bound-state resonances occur in specular intensity in atom-surface scattering. Pronounced intensity minima were first observed in 1930 by Estermann, Frisch, and Stern, during a series of gas-surface interaction experiments attempting to demonstrate the wave nature of atoms and molecules. The phenomenon has been explained in 1936 by Lennard-Jones and Devonshire in terms of resonant transitions to bound surface states. The selective adsorption binding energies can supply information on the gas-surface interaction potentials by yielding the vibrational energy spectrum of the gas atom bound to the surface. Starting from the 1970s, it has been extensively studied, both theoretically and experimentally. Energy levels measured with this technique are available for many systems. | https://en.wikipedia.org/wiki?curid=9250314 |
Picotiter plate A picotiter plate is a flat plate with multiple wells used as small test tubes. It is a miniaturised version of the microtiter plates that are standard tools in analytical research. Picotiter plates are used in the DNA sequencing strategy first exploited by a spin-off company (454 Life Sciences) and commercially available on the market. The picotiter plate platform enables parallel sequence analysis of 1.7 million of separate DNA fragments and thus is capable of sequencing entire genomes within a couple of hours. Titerplates can be produced from photosensitive glass, such as Foturan from SCHOTT Corporation. | https://en.wikipedia.org/wiki?curid=9256086 |
Halmos College of Natural Sciences and Oceanography The is a natural science college at Nova Southeastern University in Florida. The college offers programs in subjects like biology and mathematics and conducts oceanographical research. The college offers multiple bachelor's, master's and doctoral programs. The college has a presence at two campuses: in the Parker Building on the Fort Lauderdale/Davie Campus, and the Oceanographic Center, located on a site on the ocean side of Port Everglades, adjacent to the port's entrance. The center has a boat basin and affords immediate access to the Gulf Stream, the Florida Straits, and the Bahama Banks. The center is composed of three buildings, and several modulars. The main two-story building houses seven laboratories, conference rooms, workroom, and 13 offices. A second building contains a large two-story warehouse and staging area, classroom, biology laboratory, electron microscopy laboratory, darkroom, machine shop, carpentry shop, electronics laboratory, the library, student computer lab, computing center, and 15 offices. A one-story building contains a wetlab/classroom, coral workshop, and an X-ray facility. A modular laboratory is used for aquaculture studies. The Oceanographic Center grows and sells red mangroves. The Oceanographic Center is host to the National Coral Reef Institute was established by Congressional mandate in 1998. NCRI's primary objective is the assessment, monitoring, and restoration of coral reefs through basic and applied research and through training and education | https://en.wikipedia.org/wiki?curid=9258706 |
Halmos College of Natural Sciences and Oceanography The Guy Harvey Research Institute conducts basic and applied scientific research needed for effective conservation, biodiversity maintenance, restoration, and understanding of the world's wild fishes. The GHRI also provides scientific training to US and international students interested in ocean health. The GHRI is named for Jamaican artist Guy Harvey known for his marine themed works. The college supplies the Broward County Sea Turtle Conservation Program with contract employees and research facilities. | https://en.wikipedia.org/wiki?curid=9258706 |
Keuper marl is an obsolete name for multiple layers of mudstone and siltstone of Triassic age which occur beneath parts of the English Midlands and neighbouring areas e.g. Cheshire, Nottinghamshire, Devon, eastern Worcestershire and northern Yorkshire. Typically red, or occasionally green or grey, these strata are generally featureless and contain few fossils. In basin formations, thick halite-bearing layers, or rock salt deposits, are sometimes present at the base of the marl. In modern nomenclature, is included within the Mercia Mudstone Group. | https://en.wikipedia.org/wiki?curid=9285795 |
Cassini (Martian crater) Cassini is a crater on Mars named in honour of the Italian astronomer Giovanni Cassini. The name was approved in 1973, by the International Astronomical Union (IAU) Working Group for Planetary System Nomenclature. The crater measures approximately 415 kilometers in diameter and can be found at 327.9°W and 23.4°N. It is in the Arabia quadrangle of Mars. Pictures of small craters on the floor of Cassini reveal multiple layers. Some of these layers can be easily seen in the pictures below. Many places on Mars show rocks arranged in layers. Rock can form layers in a variety of ways. Volcanoes, wind, or water can produce layers. A detailed discussion of layering with many Martian examples can be found in Sedimentary Geology of Mars. Recent research leads scientists to believe that some of the craters in Arabia may have held huge lakes. Cassini Crater probably once was full of water since its rim seems to have been breached by the waters. Both inflow and outflow channels have been observed on its rim. The lake would have contained more water than Earth's Lake Baikal, our largest freshwater lake by volume. Many craters once contained lakes. | https://en.wikipedia.org/wiki?curid=9291498 |
Nucleic acid thermodynamics is the study of how temperature affects the nucleic acid structure of double-stranded DNA (dsDNA). The melting temperature ("T") is defined as the temperature at which half of the DNA strands are in the random coil or single-stranded (ssDNA) state. "T" depends on the length of the DNA molecule and its specific nucleotide sequence. DNA, when in a state where its two strands are dissociated (i.e., the dsDNA molecule exists as two independent strands), is referred to as having been denatured by the high temperature. Hybridization is the process of establishing a non-covalent, sequence-specific interaction between two or more complementary strands of nucleic acids into a single complex, which in the case of two strands is referred to as a duplex. Oligonucleotides, DNA, or RNA will bind to their complement under normal conditions, so two perfectly complementary strands will bind to each other readily. In order to reduce the diversity and obtain the most energetically preferred complexes, a technique called annealing is used in laboratory practice. However, due to the different molecular geometries of the nucleotides, a single inconsistency between the two strands will make binding between them less energetically favorable. Measuring the effects of base incompatibility by quantifying the temperature at which two strands anneal can provide information as to the similarity in base sequence between the two strands being annealed. The complexes may be dissociated by thermal denaturation, also referred to as melting | https://en.wikipedia.org/wiki?curid=9299409 |
Nucleic acid thermodynamics In the absence of external negative factors, the processes of hybridization and melting may be repeated in succession indefinitely, which lays the ground for polymerase chain reaction. Most commonly, the pairs of nucleic bases A=T and G≡C are formed, of which the latter is more stable. DNA denaturation, also called DNA melting, is the process by which double-stranded deoxyribonucleic acid unwinds and separates into single-stranded strands through the breaking of hydrophobic stacking attractions between the bases. See Hydrophobic effect. Both terms are used to refer to the process as it occurs when a mixture is heated, although "denaturation" can also refer to the separation of DNA strands induced by chemicals like formamide or urea. The process of DNA denaturation can be used to analyze some aspects of DNA. Because cytosine / guanine base-pairing is generally stronger than adenine / thymine base-pairing, the amount of cytosine and guanine in a genome (called the "GC content") can be estimated by measuring the temperature at which the genomic DNA melts. Higher temperatures are associated with high GC content. DNA denaturation can also be used to detect sequence differences between two different DNA sequences. DNA is heated and denatured into single-stranded state, and the mixture is cooled to allow strands to rehybridize. Hybrid molecules are formed between similar sequences and any differences between those sequences will result in a disruption of the base-pairing | https://en.wikipedia.org/wiki?curid=9299409 |
Nucleic acid thermodynamics On a genomic scale, the method has been used by researchers to estimate the genetic distance between two species, a process known as DNA-DNA hybridization. In the context of a single isolated region of DNA, denaturing gradient gels and temperature gradient gels can be used to detect the presence of small mismatches between two sequences, a process known as temperature gradient gel electrophoresis. Methods of DNA analysis based on melting temperature have the disadvantage of being proxies for studying the underlying sequence; DNA sequencing is generally considered a more accurate method. The process of DNA melting is also used in molecular biology techniques, notably in the polymerase chain reaction. Although the temperature of DNA melting is not diagnostic in the technique, methods for estimating "T" are important for determining the appropriate temperatures to use in a protocol. DNA melting temperatures can also be used as a proxy for equalizing the hybridization strengths of a set of molecules, e.g. the oligonucleotide probes of DNA microarrays. Annealing, in genetics, means for complementary sequences of single-stranded DNA or RNA to pair by hydrogen bonds to form a double-stranded polynucleotide. Before annealing can occur, one of the strands may need to be phosphorylated by an enzyme such as kinase to allow proper hydrogen bonding to occur. The term annealing is often used to describe the binding of a DNA probe, or the binding of a primer to a DNA strand during a polymerase chain reaction | https://en.wikipedia.org/wiki?curid=9299409 |
Nucleic acid thermodynamics The term is also often used to describe the reformation (renaturation) of reverse-complementary strands that were separated by heat (thermally denatured). Proteins such as RAD52 can help DNA anneal. DNA strand annealing is a key step in pathways of homologous recombination. In particular, during meiosis, synthesis-dependent strand annealing is a major pathway of homologous recombination. Stacking is the stabilizing interaction between the flat surfaces of adjacent bases. Stacking can happen with any face of the base, that is 5'-5', 3'-3', and vice versa. Stacking in "free" nucleic acid molecules is mainly contributed by intermolecular force, specifically electrostatic attraction among aromatic rings, a process also known as pi stacking. For biological systems with water as a solvent, hydrophobic effect contributes and helps in formation of a helix. Stacking is the main stabilizing factor in the DNA double helix. Contribution of stacking to the free energy of the molecule can be experimentally estimated by observing the bent-stacked equilibrium in nicked DNA. Such stabilization is dependent on the sequence. The extent of the stabilization varies with salt concentrations and temperature. Several formulas are used to calculate "T" values. Some formulas are more accurate in predicting melting temperatures of DNA duplexes. For DNA oligonucleotides, i.e. short sequences of DNA, the thermodynamics of hybridization can be accurately described as a two-state process | https://en.wikipedia.org/wiki?curid=9299409 |
Nucleic acid thermodynamics In this approximation one neglects the possibility of intermediate partial binding states in the formation of a double strand state from two single stranded oligonucleotides. Under this assumption one can elegantly describe the thermodynamic parameters for forming double-stranded nucleic acid AB from single-stranded nucleic acids A and B. The equilibrium constant for this reaction is formula_1. According to the Van´t Hoff equation, the relation between free energy, Δ"G", and "K" is Δ"G°" = -"RT"ln "K", where "R" is the ideal gas law constant, and "T" is the kelvin temperature of the reaction. This gives, for the nucleic acid system, formula_2. The melting temperature, "T", occurs when half of the double-stranded nucleic acid has dissociated. If no additional nucleic acids are present, then [A], [B], and [AB] will be equal, and equal to half the initial concentration of double-stranded nucleic acid, [AB]. This gives an expression for the melting point of a nucleic acid duplex of formula_3. Because Δ"G"° = Δ"H"° -"T"Δ"S"°, "T" is also given by formula_4. The terms Δ"H"° and Δ"S"° are usually given for the association and not the dissociation reaction (see the nearest-neighbor method for example). This formula then turns into: formula_5, where [B] < [A]. As mentioned, this equation is based on the assumption that only two states are involved in melting: the double stranded state and the random-coil state. However, nucleic acids may melt via several intermediate states | https://en.wikipedia.org/wiki?curid=9299409 |
Nucleic acid thermodynamics To account for such complicated behavior, the methods of statistical mechanics must be used, which is especially relevant for long sequences. The previous paragraph shows how melting temperature and thermodynamic parameters (Δ"G"° or Δ"H"° & Δ"S"°) are related to each other. From the observation of melting temperatures one can experimentally determine the thermodynamic parameters. Vice versa, and important for applications, when the thermodynamic parameters of a given nucleic acid sequence are known, the melting temperature can be predicted. It turns out that for oligonucleotides, these parameters can be well approximated by the nearest-neighbor model. The interaction between bases on different strands depends somewhat on the neighboring bases. Instead of treating a DNA helix as a string of interactions between base pairs, the nearest-neighbor model treats a DNA helix as a string of interactions between 'neighboring' base pairs. So, for example, the DNA shown below has nearest-neighbor interactions indicated by the arrows. The free energy of forming this DNA from the individual strands, Δ"G"°, is represented (at 37 °C) as Δ"G"°(predicted) = Δ"G"°(C/G initiation) + Δ"G"°(CG/GC) + Δ"G"°(GT/CA) + Δ"G"°(TT/AA) + Δ"G"°(TG/AC) + Δ"G"°(GA/CT) + Δ"G"°(A/T initiation) Except for the C/G initiation term, the first term represents the free energy of the first base pair, CG, in the absence of a nearest neighbor | https://en.wikipedia.org/wiki?curid=9299409 |
Nucleic acid thermodynamics The second term includes both the free energy of formation of the second base pair, GC, and stacking interaction between this base pair and the previous base pair. The remaining terms are similarly defined. In general, the free energy of forming a nucleic acid duplex is formula_6, where formula_7 represents the free energy associated with one of the ten possible the nearest-neighbor nucleotide pairs, and formula_8 represents its count in the sequence. Each Δ"G"° term has enthalpic, Δ"H"°, and entropic, Δ"S"°, parameters, so the change in free energy is also given by formula_9. Values of Δ"H"° and Δ"S"° have been determined for the ten possible pairs of interactions. These are given in Table 1, along with the value of Δ"G"° calculated at 37 °C. Using these values, the value of Δ"G"° for the DNA duplex shown above is calculated to be −22.4 kJ/mol. The experimental value is −21.8 kJ/mol. The parameters associated with the ten groups of neighbors shown in table 1 are determined from melting points of short oligonucleotide duplexes. Curiously, it works out that only eight of the ten groups are independent. The nearest-neighbor model can be extended beyond the Watson-Crick pairs to include parameters for interactions between mismatches and neighboring base pairs. This allows the estimation of the thermodynamic parameters of sequences containing isolated mismatches, like e.g | https://en.wikipedia.org/wiki?curid=9299409 |
Nucleic acid thermodynamics (arrows indicating mismatch) These parameters have been fitted from melting experiments and an extension of Table 1 which includes mismatches can be found in literature. A more realistic way of modeling the behavior of nucleic acids would seem to be to have parameters that depend on the neighboring groups on both sides of a nucleotide, giving a table with entries like "TCG/AGC". However, this would involve around 32 groups for Watson-Crick pairing and even more for sequences containing mismatches; the number of DNA melting experiments needed to get reliable data for so many groups would be inconveniently high. However, other means exist to access thermodynamic parameters of nucleic acids: microarray technology allows hybridization monitoring of tens of thousands sequences in parallel. This data, in combination with molecular adsorption theory allows the determination of many thermodynamic parameters in a single experiment and to go beyond the nearest neighbor model. In general the predictions from the nearest neighbor method agree reasonably well with experimental results, but some unexpected outlying sequences, calling for further insights, do exist. Finally, we should also mention the increased accuracy provided by single molecule unzipping assays which provide a wealth of new insight into the thermodynamics of DNA hybridization and the validity of the nearest-neighbour model as well. | https://en.wikipedia.org/wiki?curid=9299409 |
Ozone monitoring instrument The ozone monitoring instrument (OMI) is a visual and ultraviolet spectrometer aboard the NASA Aura spacecraft. OMI can distinguish between aerosol types, such as smoke, dust, and sulfates, and can measure cloud pressure and coverage, which provide data to derive tropospheric ozone. OMI follows in the heritage of TOMS, SBUV, GOME, SCIAMACHY, and GOMOS. It is a wide-field-imaging spectrometer with a 114° across-track viewing angle range that provides a 2600 km wide swath, enabling measurements with a daily global coverage. OMI is continuing the TOMS record for total ozone and other atmospheric parameters related to ozone chemistry and climate. The OMI project is a cooperation between the Netherlands Agency for Aerospace Programmes (NIVR), the Finnish Meteorological Institute (FMI) and the National Aeronautics and Space Agency (NASA). The OMI project was carried out under the direction of the NIVR and financed by the Ministries of Economic Affairs, Transport and Public Works and the Ministry of Education and Science. The instrument was built by Dutch Space in co-operation with Netherlands Organisation for Applied Scientific Research Science and Industry and Netherlands Institute for Space Research. The Finnish industry supplied the electronics. The scientific part of the OMI project is managed by KNMI (principal investigator Prof. Dr. P. F. Levelt), in close co-operation with NASA and the Finnish Meteorological Institute. | https://en.wikipedia.org/wiki?curid=9301973 |
Nanoscopic scale The nanoscopic scale (or nanoscale) usually refers to structures with a length scale applicable to nanotechnology, usually cited as 1–100 nanometers. A nanometer is a billionth of a meter. The nanoscopic scale is (roughly speaking) a lower bound to the mesoscopic scale for most solids. For technical purposes, the nanoscopic scale is the size at which fluctuations in the averaged properties (due to the motion and behavior of individual particles) begin to have a significant effect (often a few percent) on the behavior of a system, and must be taken into account in its analysis. The nanoscopic scale is sometimes marked as the point where the properties of a material change; above this point, the properties of a material are caused by 'bulk' or 'volume' effects, namely which atoms are present, how they are bonded, and in what ratios. Below this point, the properties of a material change, and while the type of atoms present and their relative orientations are still important, 'surface area effects' (also referred to as quantum effects) become more apparent – these effects are due to the geometry of the material (how thick it is, how wide it is, etc.), which, at these low dimensions, can have a drastic effect on quantized states, and thus the properties of a material. On October 8, 2014, the Nobel Prize in Chemistry was awarded to Eric Betzig, William Moerner and Stefan Hell for "the development of super-resolved fluorescence microscopy", which brings "optical microscopy into the nanodimension" | https://en.wikipedia.org/wiki?curid=9324236 |
Nanoscopic scale The most complex nanoscale molecular machines are proteins found within cells, often in the form of multi-protein complexes. Some biological machines are motor proteins, such as myosin, which is responsible for muscle contraction, kinesin, which moves cargo inside cells away from the nucleus along microtubules, and dynein, which moves cargo inside cells towards the nucleus and produces the axonemal beating of motile cilia and flagella. "In effect, the [motile cilium] is a nanomachine composed of perhaps over 600 proteins in molecular complexes, many of which also function independently as nanomachines." "Flexible linkers allow the mobile protein domains connected by them to recruit their binding partners and induce long-range allostery via ." Other biological machines are responsible for energy production, for example ATP synthase which harnesses energy from proton gradients across membranes to drive a turbine-like motion used to synthesise ATP, the energy currency of a cell. Still other machines are responsible for gene expression, including DNA polymerases for replicating DNA, RNA polymerases for producing mRNA, the spliceosome for removing introns, and the ribosome for synthesising proteins. These machines and their nanoscale dynamics are far more complex than any molecular machines that have yet been artificially constructed. | https://en.wikipedia.org/wiki?curid=9324236 |
Skeletochronology is used to determine the chronological age of a species of animal by counting the concentric growth rings found in a cross section of bone. This technique cannot be used for all species of bony animals. Amphibians and reptiles are commonly aged using this method because they undergo discrete annual activity cycles (i.e. winter dormancy). Cross-sections can be taken from any long bone, including femurs and phalanges, and sectioned using a microtome. Once stained with hematoxylin and viewed through a microscope, growth rings are apparent. | https://en.wikipedia.org/wiki?curid=9330285 |
Accepted and experimental value In science, and most specifically chemistry, the accepted value denotes a value of a substance accepted by almost all scientists and the experimental value denotes the value of a substance's properties found in a localized lab. | https://en.wikipedia.org/wiki?curid=9330860 |
Ledinegg instability In fluid dynamics, the occurs in two-phase flow, especially in a boiler tube, when the boiling boundary is within the tube. For a given mass flux J through the tube, the pressure drop per unit length (which typically varies as the square of the mass flux and inversely as the density i.e. as formula_1),is much less when the flow is wholly of liquid, than when the flow is wholly of steam. Thus, as the boiling boundary moves up the tube, the total pressure drop falls, potentially increasing the flow in an unstable manner. Boiler tubes normally overcome this (which is effectively a 'negative resistance' regime) by incorporating a narrow orifice at the entry, to give a stabilising pressure drop on entry. | https://en.wikipedia.org/wiki?curid=9335064 |
Global Emissions InitiAtive (GEIA) is a community effort dedicated to atmospheric emissions information exchange and competence building. GEIA was created in 1990 under the (IGBP) and is a joint IGAC / iLEAPS / AIMES activity. GEIA is governed by an international steering committee and hosts biennial conferences. information | https://en.wikipedia.org/wiki?curid=9343687 |
Orazio Antinori (28 October 1811 – 26 August 1882) was an Italian explorer and zoologist. Antinori was born in Perugia (then in the Papal States) and studied natural history in Perugia and Rome. Afterwards he collaborated with Charles Lucien Bonaparte and illustrated "Iconografia della Fauna Italica". From the middle of the 1840s he became interested in politics and worked as a journalist. In 1848 he fought against the Neapolitans with the rank of captain, and was later forced into exile. He lived in Athens and Smyrna, becoming interested in the avifauna of the area. In 1854, he accompanied Cristina Trivulzio Belgiojoso to Syria, afterwards visiting Asia Minor. In 1859 he left for Egypt and travelled up the Nile, in 1860-1861, with Carlo Piaggia (1830-1882). He sold his ornithological collection to the natural history museum of Turin. After a long stay in Tunisia, he represented Italy at the inauguration of the Suez Canal. Antinori took part in the expedition of Odoardo Beccari to Ethiopia and made important collections of natural history specimens. On his return to Italy he became the secretary of the Italian Geographical Society. In 1874, Antinori studied Chott near Tunis. In 1876 he took part in an expedition with Gustavo Chiarini and Antonio Cecchi to the province of Shewa in Ethiopia where they met with Negus Menelik at Liche, and obtained his permission to found a geographical station at Let Marefia. Antinori died in Shewa. Translated from . | https://en.wikipedia.org/wiki?curid=9344247 |
Froude–Krylov force In fluid dynamics, the Froude–Krylov force—sometimes also called the Froude–Kriloff force—is a hydrodynamical force named after William Froude and Alexei Krylov. The is the force introduced by the unsteady pressure field generated by "undisturbed" waves. The does, together with the diffraction force, make up the total non-viscous forces acting on a floating body in regular waves. The diffraction force is due to the floating body disturbing the waves. The can be calculated from: where In the simplest case the formula may be expressed as the product of the wetted surface area (A) of the floating body, and the dynamic pressure acting from the waves on the body: The dynamic pressure, formula_7, close to the surface, is given by: where | https://en.wikipedia.org/wiki?curid=9351532 |
Polymeric liquid crystal Polymeric liquid crystals are similar to monomeric liquid crystals used in displays. Both have dielectric anitroscopy, or the ability to change directions and absorb or transmit light depending on electric fields. Polymeric liquid crystals form long head-to-tail or side chain polymers, which are woven in thick mats and therefore have high viscosities. The high viscosities allow the polymeric liquid crystals to be used in complex structures, but they are harder to align, limiting their usefulness. The polymerics align in microdomains facing all different directions, which ruins the optical effect. One solution to this is to mix in a small amount of photo-curing polymer, which when spin-coated onto a surface can be hardened. Basically, the polymeric liquid crystal and photocurer are aligned in one direction, and then the photo curer is cured, "freezing" the polymeric in one direction. | https://en.wikipedia.org/wiki?curid=9356096 |
Wake Forest Institute for Regenerative Medicine The (WFIRM) is a research institute affiliated with Wake Forest School of Medicine and located in Winston-Salem, North Carolina, [[United States] WFIRM's goal is to apply the principles of [[regenerative medicine]] to repair or replace diseased tissues and organs. Among other goals, WFIRM scientists are looking for ways to create [[insulin-producing cells]] in the laboratory, [[engineered blood vessels]] for [[heart bypass surgery]] and apply [[regenerative medicine technologies]] to [[battlefield injuries]], the latter by leading a $75 million federal initiative with the [[U.S. Department of Defense]]. WFIRM is working to develop more than 40 different organs and tissues in the laboratory. [[Anthony Atala]], M.D., is the director of the institute, which is located in [[Wake Forest Innovation Quarter]] in downtown [[Winston-Salem]]. Atala was recruited by [[Wake Forest Baptist Medical Center]] in 2004, and brought many of his team members from the Laboratory for [[Tissue Engineering]] and [[Cellular Therapeutics]] at the [[Children's Hospital Boston]] and [[Harvard Medical School]]. Notable achievements announced at WFIRM have been the first [[lab-grown organ]], a [[urinary bladder]], the [[artificial urinary bladder]] to be implanted into a human, as well as [[stem cells]] harvested from the [[amniotic fluid]] of pregnant women | https://en.wikipedia.org/wiki?curid=9357386 |
Wake Forest Institute for Regenerative Medicine These stems cells are [[pluripotent]], meaning that they can be manipulated to differentiate into various types of mature cells that make up nerve, muscle, bone, and other tissues while avoiding the problems of tumor formation and ethical concerns that are associated with embryonic [[stem cells]]. In 2019, the U.S. federal [[United States Department of Health and Human Services|Department of Health and Human Services]] (HHS) supported WFIRM technology that can allow physicians to better understand damage to the body caused by inhaling [[Chlorine|chlorine gas]]. The technology is called "lung-on-a-chip" and is a part of a "miniaturized system of human organs" developed by WFIRM that can allow researchers to create models of the body's response to harmful agents. [[Category:Wake Forest University]] [[Category:Economy of Winston-Salem, North Carolina]] [[Category:Buildings and structures in Winston-Salem, North Carolina]] [[Category:2006 establishments in North Carolina]] [[Category:Life sciences industry]] | https://en.wikipedia.org/wiki?curid=9357386 |
Lin Chao Professor is a Chinese Brazilian American evolutionary biologist and geneticist. Professor Chao gained his PhD in 1977 from the University of Massachusetts Amherst, as a student of Bruce R. Levin (now at Emory University), and was a NIH postdoctoral fellow at Princeton University in the laboratory of Edward C. Cox. He spent most of his career in the Department of Biology of the University of Maryland, College Park and is currently at the Ecology, Behavior and Evolution Section of the University of California, San Diego. Professor Chao is best known for his early work on the evolution of bacteriocins, his demonstration of Muller’s ratchet in the RNA Virus Phi-6 and his work on sex in viruses. More recently, he was instrumental in the demonstration of the evolution of parasitic genetic elements in co-infecting bacteriophages and experimental tests of Fisher's geometric model. He argued that "life is evolution by natural selection". The approach generally used in his laboratory is called microbial experimental evolution. Professor Chao is married to Camilla Rang, a fellow scientist, T-shirt designer and Swedish children's book author. | https://en.wikipedia.org/wiki?curid=9361141 |
Equivalent dumping coefficient An equivalent dumping coefficient is a mathematical coefficient used in the calculation of the energy dispersed when a structure moves. As a civil engineering term, it defines the "percent of a cycle of oscillation that is absorbed (converted to heat by friction)" for the structure or sub-structure under analysis. Usually it is assumed that the equivalent dumping coefficient is linear, which is to say invariant compare to oscillatory amplitude. Modern seismic studies have shown this not to be a satisfactory assumption for larger civic structures, and have developed sophisticated amplitude and frequency based functions for "equivalent dumping coefficient". When a building moves, the materials it is made from absorb a fraction of the kinetic energy (this is especially true of concrete) due primarily to friction and to viscous or elastomeric resistance which convert motion or kinetic energy to heat. | https://en.wikipedia.org/wiki?curid=9363637 |
Web-based taxonomy is the effort by taxonomists to use the World Wide Web in order to create unified, consensus taxonomies of life on Earth. In his 2002 paper on the subject, H. Charles J. Godfray called for the creation of Web-based organisations to collect all the accumulated literature on a taxonomic group into a centralized knowledge base and make this data available through the Web as a unified taxonomy, so that it can be more easily examined and revised. Such a platform would be owned and maintained by a taxonomic working group, governed by an editor or an editorial board. An example of such a platform is FishBase. The notion of Web-based consensus taxonomies remains controversial because, as two Australian researchers pointed out, taxonomic names are not fixed but hypotheses, and therefore in constant change. | https://en.wikipedia.org/wiki?curid=9365268 |
Dirk Polder (August 23, 1919 – March 18, 2001) was a Dutch physicist who, together with Hendrik Casimir, first predicted the existence of what today is known as the Casimir-Polder force, sometimes also referred to as the "Casimir effect" or "Casimir force". He also worked on the similar topic of radiative heat transfer at nanoscale. In 1978 Polder became member of the Royal Netherlands Academy of Arts and Sciences. | https://en.wikipedia.org/wiki?curid=9370001 |
Depositional environment In geology, depositional environment or sedimentary environment describes the combination of physical, chemical and biological processes associated with the deposition of a particular type of sediment and, therefore, the rock types that will be formed after lithification, if the sediment is preserved in the rock record. In most cases the environments associated with particular rock types or associations of rock types can be matched to existing analogues. However, the further back in geological time sediments were deposited, the more likely that direct modern analogues are not available (e.g. banded iron formations). Continental Transitional Marine Others Depositional environments in ancient sediments are recognised using a combination of sedimentary facies, facies associations, sedimentary structures and fossils, particularly trace fossil assemblages, as they indicate the environment in which they lived. | https://en.wikipedia.org/wiki?curid=9373823 |
Yuli Berkovich (1944 - 2012) was a scientist who has performed experiments with seed germination in zero gravity, among others, on the International Space Station. The seedlings germinated, but died a few days later due to not having any soil or nutrients, and from capillary action. Yuli was named after his father's (who was a first deputy of the Coal Mining Industry of the USSR, and consequentially was arrested and shot as the enemy of the people under the Stalin's late rule) hero, Julius (Russian: Yuli) Cesar. As a young adult, Yuli, who was a "golden medal" HS graduate, was famous for two things: his mountaineering achievements (he was the "Snow Leopard" of the USSR and the one-time National Team Coach), and his multiple amorous escapades, whereas he bedded numerous wives and daughters of the Russian / Soviet elite, thus earning the title of "The Gigolo of the USSR". | https://en.wikipedia.org/wiki?curid=9385543 |
Landau–Pomeranchuk–Migdal effect In high-energy physics, the Landau–Pomeranchuk–Migdal effect, also known as the Landau–Pomeranchuk effect and the Pomeranchuk effect, or simply LPM effect, is a reduction of the bremsstrahlung and pair production cross sections at high energies or high matter densities. It is named in honor to Lev Landau, Isaak Pomeranchuk and Arkady Migdal. A high energy particle undergoing multiple soft scatterings from a medium will experience interference effects between adjacent scattering sites. From uncertainty as the longitudinal momentum transfer gets small the particles wavelength will increase, if the wavelength becomes longer than the mean free path in the medium (the average distance between scattering sites) then the scatterings can no longer be treated as independent events, this is the LPM effect. The Bethe–Heitler spectrum for multiple scattering induced radiation assumes that the scatterings are independent, the quantum interference between successive scatterings caused by the LPM effect leads to suppression of the radiation spectrum relative to that predicted by Bethe–Heitler. The suppression occurs in different parts of the emission spectrum, for quantum electrodynamics (QED) small photon energies are suppressed, and for quantum chromodynamics (QCD) large gluon energies are suppressed. In QED the rescattering of the high energy electron dominates the process, in QCD the emitted gluons carry color charge and interact with the medium also | https://en.wikipedia.org/wiki?curid=9386543 |
Landau–Pomeranchuk–Migdal effect Since the gluons are soft their rescattering will provide the dominant modification to the spectrum. Lev Landau and Isaak Pomeranchuk showed that the formulas for bremsstrahlung and pair creation in matter which had been formulated by Hans Bethe and Walter Heitler (the Bethe–Heitler formula) were inapplicable at high energy or high matter density. The effect of multiple Coulomb scattering by neighboring atoms reduces the cross sections for pair production and bremsstrahlung. Arkady Migdal developed a formula applicable at high energies or high matter densities which accounted for these effects. | https://en.wikipedia.org/wiki?curid=9386543 |
Memeplex Much of the study of memes focuses on groups of memes called meme complexes, or memeplexes. Like the gene complexes found in biology, memeplexes are groups of memes that are often found present in the same individual. Applying the theory of Universal Darwinism, memeplexes exist because memes will copy themselves more successfully when they are "teamed up". Examples include : Unlike inherited gene complexes, memeplexes do not have to benefit the individuals expressing them in order to replicate. Rather, because memes and memeplexes replicate virally (i.e., by horizontal transmission), they can be beneficial, inconsequential, or pathogenic to their carriers -- memes and memeplexes do not have to be true or useful to replicate. Philosopher Daniel C. Dennett, evolutionary biologist Richard Dawkins and consciousness researcher Susan Blackmore (author of "The Meme Machine") are proponents of memetics. | https://en.wikipedia.org/wiki?curid=9405089 |
Sharqi (wind) The Sharqi or sharki is a wind in the Middle East that comes from the south and southeast. It is seasonal, lasting from April to early June, and comes again between late September and November. The winds are dry and dusty, with occasional gusts up to 80 kilometres per hour (50 miles per hour) and often kick up violent sand and dust storms that can carry sand a few thousand metres high, and can close down airports for short periods of time. These winds can last for a full day at the beginning and end of the season, and for several days during the middle of the season. | https://en.wikipedia.org/wiki?curid=9407533 |
LIESST In chemistry and physics, (Light-Induced Excited Spin-State Trapping) is a method of changing the electronic spin state of a compound by means of irradiation with light. Many transition metal complexes with electronic configuration d-d are capable of spin crossover (and d when molecular symmetry is lower than O). Spin crossover refers to where a transition from the high spin (HS) state to the low spin (LS) state or vice versa occurs. Alternatives to include using thermal changes and pressure to induce spin crossover. The metal most commonly exhibiting spin crossover is iron, with the first known example, an iron(III) tris(dithiocarbamato) complex, reported by Cambi et al. in 1931. For iron complexes, involves excitation of the low spin complex with green light to a triplet state. Two successive steps of intersystem crossing result in the high spin complex. Movement from the high spin complex to the low spin complex requires excitation with red light. | https://en.wikipedia.org/wiki?curid=9430536 |
MRC 1138-262 The Spiderweb Galaxy (PGC 2826829, MRC 1138-262) is an irregular galaxy with a redshift of 2.156, which is 10.6 billion light years away. It has been recently imaged by the Hubble Space Telescope. It is formed from dozens of smaller galaxies that were seen in the process of merging through mutual gravitational attraction. | https://en.wikipedia.org/wiki?curid=9434265 |
Mary Tindale Mary Douglas Tindale (19 September 1920 – 31 March 2011) was an Australian botanist specialising in pteridology (ferns) and the genera "Acacia" and "Glycine". Tindale was born in Randwick, New South Wales, the only child of George Harold Tindale and Grace Matilda Tindale. She attended primary school in New York while her father served as British Ambassador to the United States. She returned to Sydney, Australia to attend high school at Abbotsleigh. Tindale earned a B.Sc. in Botany with Honours from Sydney University, as well as a master's degree from the same university. She became Assistant Botanist at the Royal Botanic Gardens, Sydney in 1944 and later served as the Australian Botanical Liaison Officer at the Royal Botanic Gardens, Kew from 1949–1951. After completing her Doctor of Science, she was also appointed the first principal research scientist at NSW Public Works. She retired from the Gardens in Sydney in 1983 after 39 years of service there. Tindale died in 2011. | https://en.wikipedia.org/wiki?curid=9440487 |
Thermal grill illusion The thermal grill illusion is a sensory illusion originally demonstrated in 1896 by the Swedish physician Torsten Thunberg. The illusion is created by an interlaced grill of warm (e.g., 40°C/104°F) and cool (20°C/68°F) bars. When someone presses a hand against the grill, he or she experiences the illusion of burning heat. But if the person presses against only a cool bar, only coolness is experienced; if the person presses against only a warm bar, only warmth is experienced. Researchers have used the illusion to demonstrate that burning pain sensation is in fact a mixture of both cold and heat pain and that it is only the inhibition of the cold pain "channel" that reveals the heat component. In an fMRI experiment of the illusion, researchers recently observed an activation of the thalamus not seen for control stimuli. Also, activity in a portion of the right mid/anterior insula correlated with the perceived unpleasantness of the illusion. | https://en.wikipedia.org/wiki?curid=9463641 |
Hans Fruhstorfer (7 March 1866 Passau, Germany – 9 April 1922 Munich) was a German explorer, insect trader and entomologist who specialised in Lepidoptera. He collected and described new species of exotic butterflies, especially in Adalbert Seitz's "Macrolepidoptera of the World". He is best known for his work on the butterflies of Java. His career began in 1888 when he spent two years in Brazil. The expedition was financially successful and led to his becoming a professional collector. Next he spent some time in Sri Lanka (then Ceylon), then in 1890 he went to Java for three years, visiting Sumatra. Between 1895 and 1896 he collected in Sulawesi, Lombok and Bali. In 1899, he went on a three-year journey to the United States, Oceania, Japan, China, Tonkin, Annam and Siam, returning via India. Following his travels, he settled in Geneva where he wrote monographs based on the specimens in his extensive private collection. Many of these were incorporated into Seitz's work. In taxonomy he made extensive use of the structure of the male genitalia. Fruhstorfer, in these years also studied Palearctic butterflies, Orthoptera and botany. No longer travelling himself, Fruhstorfer employed the collectors in Formosa and Franz Werner in New Guinea. Fruhstorfer's collections are deposited at the Museum für Naturkunde in Berlin, the Natural History Museum in London and the Muséum national d'histoire naturelle in Paris, as well as in many other museums. Fruhstorfer died in Munich on 9 April 1922, following a failed operation for cancer | https://en.wikipedia.org/wiki?curid=9472238 |
Hans Fruhstorfer Fruhstorfer is commemorated in the scientific name of a species of snake, "Tetralepis fruhstorferi", which is endemic to Java. Partial list: | https://en.wikipedia.org/wiki?curid=9472238 |
Relativistic electron beam Relativistic electron beams are streams of electrons moving at relativistic speeds. They are the lasing medium in free electron lasers to be used in atmospheric research conducted at entities such as the Pan-oceanic Environmental and Atmospheric Research Laboratory (PEARL) at the University of Hawaii and NASA. It has been suggested that relativistic electron beams could be used to heat and accelerate the reaction mass in electrical rocket engines that Dr. Robert W. Bussard called quiet electric-discharge engines (QEDs). | https://en.wikipedia.org/wiki?curid=9487795 |
Flux-corrected transport (FCT) is a conservative shock-capturing scheme for solving Euler equations and other hyperbolic equations which occur in gas dynamics, aerodynamics, and magnetohydrodynamics. It is especially useful for solving problems involving shock or contact discontinuities. An FCT algorithm consists of two stages, a transport stage and a flux-corrected anti-diffusion stage. The numerical errors introduced in the first stage (i.e., the transport stage) are corrected in the anti-diffusion stage. Fully multidimensional flux-corrected transport algorithms for fluids | https://en.wikipedia.org/wiki?curid=9502303 |
Suppression subtractive hybridization Subtractive hybridization is a technology that allows for PCR-based amplification of only cDNA fragments that differ between a control (driver) and experimental transcriptome. cDNA is produced from mRNA. Differences in relative abundance of transcripts are highlighted, as are genetic differences between species. The technique relies on the removal of dsDNA formed by hybridization between a control and test sample, thus eliminating cDNAs or gDNAs of similar abundance, and retaining differentially expressed, or variable in sequence, transcripts or genomic sequences. has also been successfully used to identify strain- or species-specific DNA sequences in a variety of bacteria including "Vibrio" species (Metagenomics). | https://en.wikipedia.org/wiki?curid=9509772 |
Waves and shallow water When waves travel into areas of shallow water, they begin to be affected by the ocean bottom. The free orbital motion of the water is disrupted, and water particles in orbital motion no longer return to their original position. As the water becomes shallower, the swell becomes higher and steeper, ultimately assuming the familiar sharp-crested wave shape. After the wave breaks, it becomes a wave of translation and erosion of the ocean bottom intensifies. | https://en.wikipedia.org/wiki?curid=9519674 |
Petr Černý FRSC (8 January 1934 – 7 April 2018) was a mineralogy professor at the University of Manitoba. Černý's studies focus on pegmatite. He is best known for his geological mapping of Bernic Lake, Manitoba in the 1970s. The site has since hosted several tantalum-lithium-caesium mines, for example the Tanco Mine. | https://en.wikipedia.org/wiki?curid=9523502 |
Reginald Hooley Reginald Walter Hooley (5 September 1865 – 5 May 1923) was a businessman and amateur paleontologist, collecting on the Isle of Wight. He is probably best remembered for describing the dinosaur "Iguanodon atherfieldensis", now "Mantellisaurus." Regular visits to the island resulted in the find of hundreds of fossils among which several major specimens on which he, from 1900, published fourteen scientific papers. He described remains of many turtles, and named the dinosaur "Iguanodon atherfieldensis" and the pterosaur "Ornithodesmus latidens". Hooley was a member of the Hampshire Field Club & Archaeological Society at Winchester from 1890. He was one of the founders of the Isle of Wight Natural History and Archaeological Society. He was an honorary curator of the Winchester Museum between 1918 and 1923. Reginald was born in Southampton, the son of William Hooley, a wealthy gentleman. In 1889 R.W. Hooley began to work for "Godrich & Petman", wine merchants, and later in life became managing director of that firm. Living in Portswood, in 1912 he married E.E. Holden and moved to Winchester. In 1913 he was elected a member of the Winchester city council. Hooley made his most famous finds in 1889 and 1914 when two iguanodontid skeletons were exposed by erosion at the cliffs. In 1904 the remains of "Ornithodesmus" were uncovered by a cliff fall. After Hooley's death, the paper naming "Iguanodon atherfieldensis" was posthumously published and most of the "Hooley Collection", over 1330 specimens, was, in 1924 | https://en.wikipedia.org/wiki?curid=9527259 |
Reginald Hooley acquired by the British Museum of Natural History which displays the iguanodontid skeletons in the Dinosaur Hall. In 1926 the extinct plant "Hooleya" was named after him. | https://en.wikipedia.org/wiki?curid=9527259 |
Abell S740 The is a cluster of galaxies identified in the Abell catalogue of southern rich clusters of galaxies. It is over 450 Mly away in the constellation Centaurus. It has a redshift of 10,073 km/s. | https://en.wikipedia.org/wiki?curid=9527696 |
William de Alwis William De Alwis Seneviratne (1842–1916) was a Ceylonese artist and entomologist. With his brother George (dates unknown), William made a lasting contribution to the knowledge of the lepidoptera (butterflies and moths) of Ceylon. The brothers' father, Haramanis de Alwis Seneviratne (1792–1894) was a botanical illustrator who worked at the Botanical Gardens in Ceylon at Kalutara between 1818–1822 and Peradeniya from 1822–1861. He illustrated over 2,000 plants. William was appointed to succeed him to continue the work as a botanical artist. George Thwaites, the Director of the Botanical Garden at Peradeniya between 1849 and 1879, who was impressed by the de Alwis brothers' botanical drawings, recommended to W H Gregory, the Governor of Ceylon, that they should draw from nature the butterflies and moths of Ceylon. Thwaites supervised the drawings, many of which were illustrations of specimens that he had collected himself. The drawings were accurate and later used by a number of authors publishing on the lepidoptera of Ceylon, notably by George Morrison Reid Henry and L G O Woodhouse. The De Alwis drawings are in the Natural History Museum, London. | https://en.wikipedia.org/wiki?curid=9537177 |
Allomerism is the similarity in the crystalline structure of substances of different chemical composition. | https://en.wikipedia.org/wiki?curid=9539347 |
National Undersea Research Center for the North Atlantic and Great Lakes The (NURC-NA&GL) is one of six undersea centers established by the National Oceanic and Atmospheric Administration's Undersea Research Program. It is co-located with the University of Connecticut’s Department of Marine Sciences. The center's mission includes supporting regional and national oceanography research and promoting awareness of the oceanic ecosystem through educational outreach programs. | https://en.wikipedia.org/wiki?curid=9542300 |
Self-diffusion According to IUPAC definition, self-diffusion coefficient is the diffusion coefficient formula_1 of species formula_2 when the chemical potential gradient equals zero. It is linked to the diffusion coefficient formula_3 by the equation: formula_4 Here, formula_5 is the activity of the species formula_2 in the solution and formula_7 is the concentration of formula_2. This term is commonly assumed to be equal to the tracer diffusion determined by watching the movement of an isotope in the material of interest. | https://en.wikipedia.org/wiki?curid=9544343 |
David Pegg (physicist) Professor David Pegg (born 23 May 1941) is an emeritus professor in theoretical physics at Griffith University, Australia. In his career, he has made numerous contributions to NMR, quantum optics and conceptual physics including the nature of time. His h-index is at least 38. He is a fellow of the Australian Academy of Science and a Corresponding Fellow of the Royal Society of Edinburgh. He is a recipient of the Harrie Massey Medal for Australian physics and of the Centenary Medal for his contribution to quantum theory. He is best known for the Pegg-Barnett phase formalism that provides a quantum mechanical description of the phase of light , for the invention of the DEPT sequence for nuclear magnetic resonance and for the invention of the quantum scissors device. | https://en.wikipedia.org/wiki?curid=9555511 |
Quark epoch In physical cosmology the was the period in the evolution of the early universe when the fundamental interactions of gravitation, electromagnetism, the strong interaction and the weak interaction had taken their present forms, but the temperature of the universe was still too high to allow quarks to bind together to form hadrons. The quark epoch began approximately 10 seconds after the Big Bang, when the preceding electroweak epoch ended as the electroweak interaction separated into the weak interaction and electromagnetism. During the quark epoch the universe was filled with a dense, hot quark–gluon plasma, containing quarks, leptons and their antiparticles. Collisions between particles were too energetic to allow quarks to combine into mesons or baryons. The quark epoch ended when the universe was about 10 seconds old, when the average energy of particle interactions had fallen below the binding energy of hadrons. The following period, when quarks became confined within hadrons, is known as the hadron epoch. | https://en.wikipedia.org/wiki?curid=9556852 |
Francesco Ruggiero (16 August 1957 in Naples, Italy – 18 January 2007 in Geneva, Switzerland) was an Italian physicist. In 1985, he received his Ph.D. in accelerator physics from the Scuola Normale Superiore di Pisa. He participated in the commissioning of Large Electron–Positron Collider, contributed to the Large Hadron Collider design, became the leader of the accelerator group in CERN and finally coordinated the CARE-HHH framework devoted to the LHC upgrade studies (or Super Large Hadron Collider). For a large period he also was associate editor of the prestigious Physical Review ST-AB journal. A memorial Symposium dedicated to Francesco took place at CERN on 3 October 2007. | https://en.wikipedia.org/wiki?curid=9557551 |
Plant geneticist A plant geneticist is a scientist involved with the study of genetics in botany. Typical work is done with genes in order to isolate and then develop certain plant traits. Once a certain trait, such as plant height, fruit sweetness, or tolerance to cold, is found, a plant geneticist works to improve breeding methods to ensure that future plant generations possess the desired traits. Plant genetics played a key role in the modern-day theories of heredity, beginning with Gregor Mendel's study of pea plants in the 19th century. The occupation has since grown to encompass advancements in biotechnology that have led to greater understanding of plant breeding and hybridization. Commercially, plant geneticists are sometimes employed to develop methods of making produce more nutritious, or altering plant pigments to make the food more enticing to consumers. | https://en.wikipedia.org/wiki?curid=9571778 |
Cers (wind) The Cers, also called the Narbonnais by those who live southeast of Narbonne, is a very dry wind that is colder during the winter and warmer during the summer. Originating from moist Atlantic air-masses flowing across the Toulouse area, the Cers is intensified through the Lauragais gap. Cers winds are frequent across the Aude region in south-western France. Exceptionally red sunsets and lenticularis clouds usually herald the onset of the Cers. It is closely related to the Mistral, but the term Cers refers specifically to the very strong wind in the bas-Languedoc. The opposite to this wind type is the Marin a south east wind which occurs across the Iberian Peninsula. | https://en.wikipedia.org/wiki?curid=9573286 |
Henry Brose Henry Herman Leopold Adolph Brose (15 September 1890 – 24 February 1965) was an Australian physicist. Born in Adelaide, he attended Prince Alfred College and graduated from the University of Adelaide in 1910 with a B.Sc. in mathematics. A member of the Adelaide University Athletics Club, Brose was awarded a University Blue for Athletics in 1910. In 1911-12 he taught French at Prince Alfred College, and in 1913 was awarded the Rhodes Scholarship for South Australia. Brose went up to Christ Church, Oxford to study mathematics. While visiting relatives in Hamburg in 1914, he was arrested by the German authorities and interned as a civilian prisoner for the duration of the First World War. During his captivity Brose became interested in the Theory of Relativity and translated some German texts into English. On return to Oxford, he was awarded B.A. and M.A. degrees in 1919, and in 1925 he completed a D. Phil. on the motion of electrons in oxygen, under the supervision of John Sealy Edward Townsend. He then went on to hold a number of academic positions including Lecturer in Physics at the University of Sydney and Professor of Physics at the University of Nottingham. From 1920 and 1936 he translated sixteen physics texts from German into English. Brose later went on to work in cancer research, holding positions as a physicist, a pathologist and a biochemist | https://en.wikipedia.org/wiki?curid=9575269 |
Henry Brose Brose made an enormous contribution to the scientific world of his time both in Australia and across the world, as indicated by his vast collection of Manuscripts still archived in the University of Adelaide. Brose acted as an interpreter when Einstein visited the University of Nottingham in 1930 and 1931. | https://en.wikipedia.org/wiki?curid=9575269 |
Antoni Jakubski Antoni Władysław Jakubski (; 1885–1962) was a Polish zoologist and explorer. Jakubski was born in Lemberg (Lwów), Galicia, Austria-Hungary (now Lviv, Ukraine) on 28 March 1885. He studied zoology from Prof. Józef Nusbaum-Hilarowicz at the Lwów University where he received a habilitation in 1917. In 1909-1910, he traveled to East Africa, becoming, on 13 March 1910, the first Pole to climb Mount Kilimanjaro. He crossed Tanganyika on foot, traveling from the Indian Ocean to the lakes Nyasa and Rukwa in order to study their fauna. During the First World War, Jakubski fought in the Polish Legions. For his military service, he was awarded with a fifth class Virtuti Militari order and a Cross of the Valiant. From 1919 to 1939, he worked at the Poznań University. In 1923, he set up the Maritime Fishing Laboratory at Hel on the Baltic Sea. After the Second World War, during which he was an inmate of Nazi concentration camps, Jakubski settled in the United Kingdom where he was employed in the British Museum. He died in London on 20 May 1962. Jakubski's area of research comprised faunistics, zoogeography, comparative anatomy and history of zoology. His works include: | https://en.wikipedia.org/wiki?curid=9580173 |
Bioprocess engineering Bioprocess engineering, also biochemical engineering, is a specialization of chemical engineering or Biological engineering, It deals with the design and development of equipment and processes for the manufacturing of products such as agriculture, food, feed, pharmaceuticals, nutraceuticals, chemicals, and polymers and paper from biological materials & treatment of waste water. is a conglomerate of mathematics, biology and industrial design, and consists of various spectrums like designing of bioreactors, study of fermentors (mode of operations etc.). It also deals with studying various biotechnological processes used in industries for large scale production of biological product for optimization of yield in the end product and the quality of end product. may include the work of mechanical, electrical, and industrial engineers to apply principles of their disciplines to processes based on using living cells or sub component of such cells. | https://en.wikipedia.org/wiki?curid=9580771 |
William Fowler Mountford Copeland (13 February 1872 – 17 January 1953) was a British amateur horticulturist. He was attended Trinity College, Cambridge. He was the son of Richard Pirie Copeland and grandson of William Taylor Copeland. husband of Beatrice Augusta Mary Geddes and father of Mary Beatrice, 1912–2003; Irene Emily, 1914–1996; and John Richard Geddes, 1917–1946, after whom were named the varieties of daffodils 'Mrs. William Copeland', 'John Evelyn', 'Irene Copeland' and 'Mary Copeland' respectively. | https://en.wikipedia.org/wiki?curid=9583640 |
Jan Ambjørn is a Danish physicist regarded as the primary founder of Causal Dynamical Triangulation Theory (CDT). Ambjørn began in the early 1990s searching for a physics model that bonded quantum mechanics and relativistic gravity in a way that didn't require supersymmetry. By 1994, he argued a simpler way to represent quantum gravity was to use Lorentzian space-time geometry as a framework. His first major publication on the lattice model that would become CDT theory was released in 1998. It was then that he and Renate Loll made triangulation and the causal approach the cornerstones to the lattice gauge theory. The theory of Causal Dynamical Triangulations faced harsh scrutiny for some years because most physicists preferred models that required more dimensions and a fixed background. By 2004, Ambjørn's assertion of the benefits to a non-perturbative quantum gravity model regained attention. As of 2007, Ambjørn continues to research lattice gauge, string, and quantum gravity theories; matrix models and their applications; and statistical theories of random surfaces and paths. He is currently sharing a position as a professor at the Niels Bohr Institute and the Radboud University Nijmegen. Ambjørn has worked with or been acknowledged as an influence by quantum physicists such as Renate Loll, Fotini Markopoulou, Jerzy Jurkiewicz, and Lee Smolin. | https://en.wikipedia.org/wiki?curid=9584270 |
Charles C. Bradley (1911 – May 18, 2002) was a professor in geology at the Montana State College. He received his bachelors, masters, and doctorate degrees from University of Wisconsin–Madison. | https://en.wikipedia.org/wiki?curid=9591319 |
Acid growth refers to the ability of plant cells and plant cell walls to elongate or expand quickly at low (acidic) pH. The cell wall needs to be modified in order to maintain the turgor pressure. This modification is controlled by plant hormones like auxin. Auxin also controls the expression of some cell wall genes. This form of growth does not involve an increase in cell number. During acid growth, plant cells enlarge rapidly because the cell walls are made more extensible by expansin, a pH-dependent wall-loosening protein. Expansin loosens the network-like connections between cellulose microfibrils within the cell wall, which allows the cell volume to increase by turgor and osmosis. A typical sequence leading up to this would involve the introduction of a plant hormone (auxin, for example) that causes protons (H ions) to be pumped out of the cell into the cell wall. As a result, the cell wall solution becomes more acidic. It was suggested by different scientist that the epidermis is a unique target of the auxin but this theory has been disapproved over time. This activates expansin activity, causing the wall to become more extensible and to undergo wall stress relaxation, which enables the cell to take up water and to expand. The acid growth theory has been very controversial in the past. | https://en.wikipedia.org/wiki?curid=9600102 |
Retention distance Retention distance, or "R", is a concept in thin layer chromatography, designed for quantitative measurement of "equal-spreading" of the spots on the chromatographic plate and one of the Chromatographic response functions. It is calculated from the following formula: formula_1 where "n" is the number of compounds separated, "R" are the Retention factor of the compounds sorted in non-descending order, "R" = 0 and "R" = 1. The coefficient lies always in range <0,1> and 0 indicates worst case of separation (all R values equal to 0 or 1), value 1 indicates ideal equal-spreading of the spots, for example (0.25,0.5,0.75) for three solutes, or (0.2,0.4,0.6,0.8) for four solutes. This coefficient was proposed as an alternative to earlier approaches, such as delta-Rf, delta-Rf product or MRF (Multispot Response Function). Besides its stable range, the advantage is a stable distribution as a random variable, regardless of compounds investigated. In contrast to the similar concept called Retention uniformity, "R" is sensitive to "R" values close to 0 or 1, or close to themselves. If two values are not separated, it is equal to 0. For example, the "R" values (0,0.2,0.2,0.3) (two compounds not separated at 0.2 and one at the start ) result in "R" equal to 0, but "R" equal to 0.3609. When some distance from 0 and spots occurs, the value is larger, for example "R" values (0.1,0.2,0.25,0.3) give "R" = 0.4835, "R" = 0.4066. | https://en.wikipedia.org/wiki?curid=9607629 |
Emanuel Bunzel (1828–1895), was an Austrian paleontologist. In 1871, he described a skull fragment found in an Austrian coal mine years before by colleagues Ferdinand Stoliczka and Eduard Suess as the type specimen for the dinosaur genus "Struthiosaurus", the first discovered in the region. Another dinosaur he described initially as a species of "Iguanodon" ("I. suessii") has since been reassigned to the genus "Mochlodon". | https://en.wikipedia.org/wiki?curid=9621670 |
Anatoly Konstantinovich Rozhdestvensky (, 1920–1983) was a Russian paleontologist responsible for naming many dinosaurs, including "Aralosaurus" and "Probactrosaurus". | https://en.wikipedia.org/wiki?curid=9621847 |
Darwin–Radau equation In astrophysics, the (named after Rodolphe Radau and Charles Galton Darwin) gives an approximate relation between the moment of inertia factor of a planetary body and its rotational speed and shape. The moment of inertia factor is directly related to the largest principal moment of inertia, "C". It is assumed that the rotating body is in hydrostatic equilibrium and is an ellipsoid of revolution. The states where "M" and "R" represent the mass and mean equatorial radius of the body. Here λ is the d'Alembert parameter and the Radau parameter η is defined as where "q" is the geodynamical constant and ε is the geometrical flattening where "R" is the mean polar radius and "R" is the mean equatorial radius. For Earth, formula_5 and formula_6, which yields formula_7, a good approximation to the measured value of 0.3307. | https://en.wikipedia.org/wiki?curid=9628193 |
De Vaucouleurs' law de Vaucouleurs' law, also known as the de Vaucouleurs profile or de Vaucouleurs model, describes how the surface brightness formula_1 of an elliptical galaxy varies as a function of apparent distance formula_2 from the center of the galaxy: By defining "R" as the radius of the isophote containing half of the total luminosity of the galaxy, the half-light radius, de Vaucouleurs' profile may be expressed as: or where "I" is the surface brightness at "R". This can be confirmed by noting de Vaucouleurs' model is a special case of Sersic's model, with a Sersic index of n=4. A number of (internal) density profiles that approximately reproduce de Vaucouleurs' law after projection onto the plane of the sky include Jaffe's model and Dehnen's model. The model is named after Gérard de Vaucouleurs who first formulated it in 1948. Although an empirical model rather than a law of physics, it was so entrenched in astronomy during the 20th century that it was referred to as a "law". | https://en.wikipedia.org/wiki?curid=9632204 |
István Apáthy István Apáthy, also known as Stephan Apáthy (1863–1922), was a Hungarian zoologist and histologist, known for his work in medical science and microscope technique. He particularly studied neurofibrils, and was known for improving microscopic techniques for dealing with tissue samples. Apáthy was a professor at the Franz Joseph University. He also theorized on the "social and political aspects" of eugenics. Taxa named in honor of Stephan Apáthy include: | https://en.wikipedia.org/wiki?curid=9634360 |
Mucigel is a slimy substance that covers the root cap of the roots of plants. It is a highly hydrated polysaccharide, most likely a pectin, which is secreted from the outermost (epidermal) cells of the rootcap. is formed in the Golgi bodies of such cells, and is secreted through the process of exocytosis. The layer of microorganism-rich soil surrounding the mucigel is called the rhizosphere. serves several functions, including: | https://en.wikipedia.org/wiki?curid=9637332 |
Amorphism An amorphism, in chemistry, crystallography and, by extension, to other areas of the natural sciences is a substance or feature that lacks an ordered form. In the specific case of crystallography, an amorphic material is one that lacks long range (significant) crystalline order at the molecular level. In the history of chemistry, "amorphism" was recognised even before the discovery of the nature of the exact atomic crystalline lattice structure. The concept of amorphism can also be found in the fields of art, biology, archaeology and philosophy as a characterisation of objects without form, or with random or unstructured form. | https://en.wikipedia.org/wiki?curid=9664551 |
Legion (taxonomy) The legion, in biological classification, is a non-obligatory taxonomic rank within the Linnaean hierarchy sometimes used in zoology. In zoological taxonomy, the legion is: Legions may be grouped into superlegions or subdivided into sublegions, and these again into infralegions. Legions and their super/sub/infra groups have been employed in some classifications of birds and mammals. Full use is made of all of these (along with cohorts and supercohorts) in, for example, McKenna and Bell's classification of mammals. | https://en.wikipedia.org/wiki?curid=9668061 |
Pharmacokinetics (from Ancient Greek "pharmakon" "drug" and "kinetikos" "moving, putting in motion"; see chemical kinetics), sometimes abbreviated as PK, is a branch of pharmacology dedicated to determine the fate of substances administered to a living organism. The substances of interest include any chemical xenobiotic such as: pharmaceutical drugs, pesticides, food additives, cosmetics, etc. It attempts to analyze chemical metabolism and to discover the fate of a chemical from the moment that it is administered up to the point at which it is completely eliminated from the body. is the study of how an organism affects a drug, whereas pharmacodynamics (PD) is the study of how the drug affects the organism. Both together influence dosing, benefit, and adverse effects, as seen in PK/PD models. describes how the body affects a specific xenobiotic/chemical after administration through the mechanisms of absorption and distribution, as well as the metabolic changes of the substance in the body (e.g. by metabolic enzymes such as cytochrome P450 or glucuronosyltransferase enzymes), and the effects and routes of excretion of the metabolites of the drug. Pharmacokinetic properties of chemicals are affected by the route of administration and the dose of administered drug. These may affect the absorption rate. Models have been developed to simplify conceptualization of the many processes that take place in the interaction between an organism and a chemical substance | https://en.wikipedia.org/wiki?curid=9674107 |
Pharmacokinetics One of these, the multi-compartmental model, is the most commonly used approximations to reality; however, the complexity involved in adding parameters with that modelling approach means that "monocompartmental models" and above all "two compartmental models" are the most-frequently used. The various compartments that the model is divided into are commonly referred to as the ADME scheme (also referred to as LADME if liberation is included as a separate step from absorption): The two phases of metabolism and excretion can also be grouped together under the title elimination. The study of these distinct phases involves the use and manipulation of basic concepts in order to understand the process dynamics. For this reason, in order to fully comprehend the "kinetics" of a drug it is necessary to have detailed knowledge of a number of factors such as: the properties of the substances that act as excipients, the characteristics of the appropriate biological membranes and the way that substances can cross them, or the characteristics of the enzyme reactions that inactivate the drug. All these concepts can be represented through mathematical formulas that have a corresponding graphical representation | https://en.wikipedia.org/wiki?curid=9674107 |
Pharmacokinetics The use of these models allows an understanding of the characteristics of a molecule, as well as how a particular drug will behave given information regarding some of its basic characteristics such as its acid dissociation constant (pKa), bioavailability and solubility, absorption capacity and distribution in the organism. The model outputs for a drug can be used in industry (for example, in calculating bioequivalence when designing generic drugs) or in the clinical application of pharmacokinetic concepts. Clinical pharmacokinetics provides many performance guidelines for effective and efficient use of drugs for human-health professionals and in veterinary medicine. The following are the most commonly measured pharmacokinetic metrics: The units of the dose in the table are expressed in moles (mol) and molar (M). To express the metrics of the table in units of mass, instead of Amount of substance, simply replace 'mol' with 'g' and 'M' with 'g/dm3'. Similarly, other units in the table may be expressed in units of an equivalent dimension by scaling. In pharmacokinetics, "steady state" refers to the situation where the overall intake of a drug is fairly in dynamic equilibrium with its elimination. In practice, it is generally considered that steady state is reached when a time of 3 to 5 times the half-life for a drug after regular dosing is started. Pharmacokinetic modelling is performed by noncompartmental or compartmental methods | https://en.wikipedia.org/wiki?curid=9674107 |
Pharmacokinetics Noncompartmental methods estimate the exposure to a drug by estimating the area under the curve of a concentration-time graph. Compartmental methods estimate the concentration-time graph using kinetic models. Noncompartmental methods are often more versatile in that they do not assume any specific compartmental model and produce accurate results also acceptable for bioequivalence studies. The final outcome of the transformations that a drug undergoes in an organism and the rules that determine this fate depend on a number of interrelated factors. A number of functional models have been developed in order to simplify the study of pharmacokinetics. These models are based on a consideration of an organism as a number of related compartments. The simplest idea is to think of an organism as only one homogenous compartment. This "monocompartmental model" presupposes that blood plasma concentrations of the drug are a true reflection of the drug's concentration in other fluids or tissues and that the elimination of the drug is directly proportional to the drug's concentration in the organism (first order kinetics). However, these models do not always truly reflect the real situation within an organism. For example, not all body tissues have the same blood supply, so the distribution of the drug will be slower in these tissues than in others with a better blood supply | https://en.wikipedia.org/wiki?curid=9674107 |
Pharmacokinetics In addition, there are some tissues (such as the brain tissue) that present a real barrier to the distribution of drugs, that can be breached with greater or lesser ease depending on the drug's characteristics. If these relative conditions for the different tissue types are considered along with the rate of elimination, the organism can be considered to be acting like two compartments: one that we can call the "central compartment" that has a more rapid distribution, comprising organs and systems with a well-developed blood supply; and a "peripheral compartment" made up of organs with a lower blood flow. Other tissues, such as the brain, can occupy a variable position depending on a drug's ability to cross the barrier that separates the organ from the blood supply. This "two compartment model" will vary depending on which compartment elimination occurs in. The most common situation is that elimination occurs in the central compartment as the liver and kidneys are organs with a good blood supply. However, in some situations it may be that elimination occurs in the peripheral compartment or even in both. This can mean that there are three possible variations in the two compartment model, which still do not cover all possibilities. This model may not be applicable in situations where some of the enzymes responsible for metabolizing the drug become saturated, or where an active elimination mechanism is present that is independent of the drug's plasma concentration | https://en.wikipedia.org/wiki?curid=9674107 |
Pharmacokinetics In the real world each tissue will have its own distribution characteristics and none of them will be strictly linear. If we label the drug's volume of distribution within the organism Vd and its volume of distribution in a tissue Vd the former will be described by an equation that takes into account all the tissues that act in different ways, that is: This represents the "multi-compartment model" with a number of curves that express complicated equations in order to obtain an overall curve. A number of computer programs have been developed to plot these equations. However complicated and precise this model may be, it still does not truly represent reality despite the effort involved in obtaining various distribution values for a drug. This is because the concept of distribution volume is a relative concept that is not a true reflection of reality. The choice of model therefore comes down to deciding which one offers the lowest margin of error for the drug involved. Noncompartmental PK analysis is highly dependent on estimation of total drug exposure. Total drug exposure is most often estimated by area under the curve (AUC) methods, with the trapezoidal rule (numerical integration) the most common method. Due to the dependence on the length of "x" in the trapezoidal rule, the area estimation is highly dependent on the blood/plasma sampling schedule. That is, the closer time points are, the closer the trapezoids reflect the actual shape of the concentration-time curve | https://en.wikipedia.org/wiki?curid=9674107 |
Pharmacokinetics The number of time points available in order to perform a successful NCA analysis should be enough to cover the absorption, distribution and elimination phase to accurately characterize the drug. Beyond AUC exposure measures, parameters such as Cmax (maximum concentration), Tmax(time at maximum concentration), CL and Vd can also be reported using NCA methods. Compartmental PK analysis uses kinetic models to describe and predict the concentration-time curve. PK compartmental models are often similar to kinetic models used in other scientific disciplines such as chemical kinetics and thermodynamics. The advantage of compartmental over some noncompartmental analyses is the ability to predict the concentration at any time. The disadvantage is the difficulty in developing and validating the proper model. Compartment-free modelling based on curve stripping does not suffer this limitation. The simplest PK compartmental model is the one-compartmental PK model with IV bolus administration and first-order elimination. The most complex PK models (called PBPK models) rely on the use of physiological information to ease development and validation. "Linear pharmacokinetics" is so-called because the graph of the relationship between the various factors involved (dose, blood plasma concentrations, elimination, etc.) gives a straight line or an approximation to one. For drugs to be effective they need to be able to move rapidly from blood plasma to other body fluids and tissues | https://en.wikipedia.org/wiki?curid=9674107 |
Pharmacokinetics The change in concentration over time can be expressed as formula_2 The graph for the non-linear relationship between the various factors is represented by a curve; the relationships between the factors can then be found by calculating the dimensions of different areas under the curve. The models used in "non-linear pharmacokinetics" are largely based on Michaelis–Menten kinetics. A reaction's factors of non-linearity include the following: It can therefore be seen that non-linearity can occur because of reasons that affect the entire pharmacokinetic sequence: absorption, distribution, metabolism and elimination. Variable volume pharmacokinetic models can be drug centered models that imply a volume of drug distribution to be that volume in which the drug is distributed at that elapsed time following drug administration. Another possibility occurs when the body volume is changing in time, which would occur, for example, during dialysis when the volume in which a drug can be distributed is itself changing in time. At a practical level, a drug's bioavailability can be defined as the proportion of the drug that reaches its site of action. From this perspective the intravenous administration of a drug provides the greatest possible bioavailability, and this method is considered to yield a bioavailability of 1 (or 100%) | https://en.wikipedia.org/wiki?curid=9674107 |
Pharmacokinetics Bioavailability of other delivery methods is compared with that of intravenous injection (absolute bioavailability) or to a standard value related to other delivery methods in a particular study (relative bioavailability). Once a drug's bioavailability has been established it is possible to calculate the changes that need to be made to its dosage in order to reach the required blood plasma levels. Bioavailability is, therefore, a mathematical factor for each individual drug that influences the administered dose. It is possible to calculate the amount of a drug in the blood plasma that has a real potential to bring about its effect using the formula: where "De" is the effective dose, "B" bioavailability and "Da" the administered dose. Therefore, if a drug has a bioavailability of 0.8 (or 80%) and it is administered in a dose of 100 mg, the equation will demonstrate the following: That is the 100 mg administered represents a blood plasma concentration of 80 mg that has the capacity to have a pharmaceutical effect. This concept depends on a series of factors inherent to each drug, such as: These concepts, which are discussed in detail in their respective titled articles, can be mathematically quantified and integrated to obtain an overall mathematical equation: where Q is the drug's purity. where formula_8 is the drug's rate of administration and formula_9 is the rate at which the absorbed drug reaches the circulatory system | https://en.wikipedia.org/wiki?curid=9674107 |
Pharmacokinetics Finally, using the Henderson-Hasselbalch equation, and knowing the drug's formula_10 (pH at which there is an equilibrium between its ionized and non ionized molecules), it is possible to calculate the non ionized concentration of the drug and therefore the concentration that will be subject to absorption: When two drugs have the same bioavailability, they are said to be biological equivalents or bioequivalents. This concept of bioequivalence is important because it is currently used as a yardstick in the authorization of generic drugs in many countries. A number of phases occur once the drug enters into contact with the organism, these are described using the acronym LADME: Some textbooks combine the first two phases as the drug is often administered in an active form, which means that there is no liberation phase. Others include a phase that combines distribution, metabolism and excretion into a disposition phase. Other authors include the drug's toxicological aspect in what is known as "ADME-Tox" or "ADMET". Each of the phases is subject to physico-chemical interactions between a drug and an organism, which can be expressed mathematically. is therefore based on mathematical equations that allow the prediction of a drug's behavior and which place great emphasis on the relationships between drug plasma concentrations and the time elapsed since the drug's administration. Bioanalytical methods are necessary to construct a concentration-time profile | https://en.wikipedia.org/wiki?curid=9674107 |
Pharmacokinetics Chemical techniques are employed to measure the concentration of drugs in biological matrix, most often plasma. Proper bioanalytical methods should be selective and sensitive. For example, microscale thermophoresis can be used to quantify how the biological matrix/liquid affects the affinity of a drug to its target. is often studied using mass spectrometry because of the complex nature of the matrix (often plasma or urine) and the need for high sensitivity to observe concentrations after a low dose and a long time period. The most common instrumentation used in this application is LC-MS with a triple quadrupole mass spectrometer. Tandem mass spectrometry is usually employed for added specificity. Standard curves and internal standards are used for quantitation of usually a single pharmaceutical in the samples. The samples represent different time points as a pharmaceutical is administered and then metabolized or cleared from the body. Blank samples taken before administration are important in determining background and ensuring data integrity with such complex sample matrices. Much attention is paid to the linearity of the standard curve; however it is common to use curve fitting with more complex functions such as quadratics since the response of most mass spectrometers is not linear across large concentration ranges. There is currently considerable interest in the use of very high sensitivity mass spectrometry for microdosing studies, which are seen as a promising alternative to animal experimentation | https://en.wikipedia.org/wiki?curid=9674107 |
Pharmacokinetics Recent studies show that Secondary electrospray ionization (SESI-MS) can be used in drug monitoring, presenting the advantage of avoiding animal sacrifice. "Population pharmacokinetics" is the study of the sources and correlates of variability in drug concentrations among individuals who are the target patient population receiving clinically relevant doses of a drug of interest. Certain patient demographic, pathophysiological, and therapeutical features, such as body weight, excretory and metabolic functions, and the presence of other therapies, can regularly alter dose-concentration relationships and can explain variability in exposures. For example, steady-state concentrations of drugs eliminated mostly by the kidney are usually greater in patients suffering from kidney failure than they are in patients with normal kidney function receiving the same drug dosage. Population pharmacokinetics seeks to identify the measurable pathophysiologic factors and explain sources of variability that cause changes in the dose-concentration relationship and the extent of these changes so that, if such changes are associated with clinically relevant and significant shifts in exposures that impact the therapeutic index, dosage can be appropriately modified. An advantage of population pharmacokinetic modelling is its ability to analyse sparse data sets (sometimes only one concentration measurement per patient is available) | https://en.wikipedia.org/wiki?curid=9674107 |
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