text stringlengths 11 1.65k | source stringlengths 38 44 |
|---|---|
Spin echo small angle neutron scattering (SESANS) measures structures from around 20 to 2000nm in size. The information is presented as a real-space (similar to g(r)) as opposed to a reciprocal space (q(r)) mapping. The this can simplify the interpretation for some systems. SESANS is useful for studying processes that occur over relatively long time scales, as data collection is often slow, but large length scales. Aggregation of colloids, block copolymer micelles, Stöber silica particles being a prime examples. The technique offers some advantages over SANS, but there are fewer SESANS instruments available than SANS instruments. Facilities for SESANS exist at TUDelft (Netherlands) and Rutherford Appleton Laboratory (UK). | https://en.wikipedia.org/wiki?curid=62181250 |
Robert C. Armstrong Robert Calvin Armstrong is director of the Massachusetts Institute of Technology Energy Initiative. He has been a member of the MIT faculty since 1973, and served as head of the Department of Chemical Engineering from 1996 to 2007. He was elected a member of the National Academy of Engineering in 2008. | https://en.wikipedia.org/wiki?curid=62181814 |
Hunic superterrane The is a terrane that is now attached to Europe and Asia. At the end of the Ordovician or beginning of the Silurian it separated from Gondwana and joined Laurasia at the beginning of the Carboniferous, at the time of the Variscan orogeny. Rather than being a single block, there were apparently two groups of blocks, the European Hunic terranes and the Asian Hunic terranes. The collision with Laurasia (specifically, with the Kipchak Arc) formed what is now known as Kazakhstania according to one geological model of the ancient Earth. The Hunic terranes are named after the Huns, since they are found in the areas that the Huns occupied. | https://en.wikipedia.org/wiki?curid=62191085 |
Southern exposure (terminology) Southern exposure is increased sunlight received by south-facing land, walls, windows, and other relevant entities in the Northern Hemisphere. Southern exposure is often considered "full sun". Sunlight differentials for southern exposure are caused by the 23-degree axis tilt of the Earth, which creates an uneven distribution of sunlight based on geographical location. Southern exposure is commonly discussed in real estate discourse because it can affect a structure's capacity for solar energy options. Southern exposure is also important to landscaping and land conservation. It impacts the native plant life that will survive in a given area by affecting the optimal landscaping compositions, gardening patterns, and seasonal growth of flora. | https://en.wikipedia.org/wiki?curid=62191409 |
Baydzharakh (), a term based in the Yakut language, is a roughly cone-shaped natural rock formation. They are usually composed of siltstone, silty peat or loam. Baydzharakhs form owing to thermokarst activity in periglacial areas. They are the result of a cryolithological process by which polygonal ice-wedges thaw within the permafrost. These formations usually reach a height between and with an area at the base between to . In the first phase of the ice melting process baydzharakhs have a pillar-like shape. When the ice mass in the surrounding rocks is high, they swell and form rounded depressions known as "alas" (Алаас) in Yakut. These depressions are usually between to in depth, but exceptionally may be deep. Baydzharakhs come often combined witn "alas" depressions. formations are found in different places across the East Siberian Lowland, such as Muostakh Island, Stolbovoy Island, Kotelny Island and the Ulakhan-Sis Range, as well as in scattered places of the Yana-Indigirka Lowland. In 1950 a lonely baydzharakh was the last vestige of now disappeared Semyonovsky Island in the Laptev Sea. They often occur together with Yedoma (Едома) complexes and in areas with ice-wedges of considerable thickness. | https://en.wikipedia.org/wiki?curid=62232882 |
Hughes–Ingold symbol A describes various details of the reaction mechanism and overall result of a chemical reaction. For example, an S2 reaction is a substitution reaction ("S") by a nucleophilic process ("N") that is bimolecular ("2" molecular entities involved) in its rate-determining step. By contrast, an E2 reaction is an elimination reaction, an S2 reaction involves electrophilic substitution, and an S1 reaction is unimolecular. The system is named for British chemists Edward D. Hughes and Christopher Kelk Ingold. | https://en.wikipedia.org/wiki?curid=62256831 |
Stanley Charles Seagrief (21 February 1927 Salisbury - 14 July 1995) was a South African botanist and botanical illustrator, specialising in phycology. His first post-school studies were at Rhodes University in 1944–49, graduating with a B.Sc. in 1947 and a M.Sc. in 1950. He then attended Cambridge University in 1950-53 where he obtained a Ph.D. in 1955 for 'A Pollen Analytic Investigation of the Quaternary Period in Britain.' | https://en.wikipedia.org/wiki?curid=62259626 |
Margaret McCarthy (academic) Margaret M. "Peg" McCarthy (born August 21, 1958) is an American neuroscientist and pharmacologist. She is the James & Carolyn Frenkil Endowed Dean's Professor at the University of Maryland School of Medicine, where she is also Professor and Chair of the Department of Pharmacology. She is known for her research on the neuroscience of sex differences and their underlying mechanisms. In 2019, she received the Gill Transformative Investigator Award from the Gill Center for Biomolecular Science at Indiana University. Dr. McCarthy received a Bachelor of Science and Master of Arts in Biology from the University of Missouri in 1981 and 1984. She then attended Rutgers University where she received a PhD. in Behavioral Neuroscience in 1989. Following her PhD., she completed a postdoctoral fellowship with Rockefeller University, where she studied Neurobiology. She completed a fellowship at the National Institutes of Health in Neurogenetics in 1993. | https://en.wikipedia.org/wiki?curid=62261435 |
Scandinavium (genus) Scandinavium is a genus of Gram-negative, facultative anaerobic, oxidase-negative, rod-shaped, motile bacteria of the family "Enterobacteriaceae." It contains a single species, Scandinavium goeteborgense. The type strain of the species is "S. goeteborgense" CCUG 66741 = CECT 9823 = NCTC 14286 and its genome sequence is publicly available in DNA Data Bank of Japan, European Nucleotide Archive and GenBank under the accession number LYLP00000000. | https://en.wikipedia.org/wiki?curid=62285440 |
Northumberland Trough The Northumberland Trough, also known as the Northumberland Basin, is an element of the structural geology of northern England, the origin of which dates back to the Carboniferous period when a block and basin province was established throughout the Pennine region. The trough is an ENE-WSW aligned half-graben, an asymmetric depositional basin. It is defined to the south by the Stublick and Ninety Fathom faults, which separate the trough from the Alston Block. To the north, where its depth is least, the trough's boundary with the Cheviot Block is less well-defined; nevertheless, the south-easterly down-throwing Featherwood and Alwinton faults can be identified along this margin. To the west, the trough is continuous with the Solway Basin. The surrounding blocks are buoyed up by granite batholiths maintaining these regions of the upper crust as areas of raised relief. Geological Structure of Great Britain | https://en.wikipedia.org/wiki?curid=62304118 |
Organix Inc is a US fine chemicals company specialising in chemical synthesis of analytical standards and custom synthesis of finished compounds and intermediates. Organix carries out research and development of novel molecules used in a variety of pharmaceutical research applications. Some notable compounds include; | https://en.wikipedia.org/wiki?curid=62359279 |
NGC 3749 is a spiral galaxy located in the constellation of Centaurus at an approximate distance of 130.52 million light-years. was discovered in 1835 by John Herschel. | https://en.wikipedia.org/wiki?curid=62374983 |
Acta Geologica Polonica is a peer-reviewed open access scholarly journal publishing original papers on all aspects of geology. It is published by the Institute of Geology, University of Warsaw. The current editor-in-chief is Piotr Łuczyński. The journal is abstracted and indexed in: | https://en.wikipedia.org/wiki?curid=62393071 |
Giomar Helena Borrero-Pérez is a Colombian marine biologist. In 2012 she became the sixth Colombian scientist to be awarded a L'Oréal-UNESCO For Women in Science Award. Her work considers the conservation of sea cucumbers. Borrero was born in Mitú. She attended the National Indigenous Normal School of Mitú until 1992. Borrero was awarded a scholarship from Ecopetrol to attend Jorge Tadeo Lozano University, where she studied marine biology. She moved to Spain for her doctoral studies, where she worked on biodiversity at the University of Murcia. Whilst in Spain she started to work on the "Holothuroidea" species. Borrero completed an internship at the José Benito Vives de Andréis Marine and Coastal Research Institute. She served as a curator at the Museum of Marine History in Colombia. Her research considers sea cucumbers from around the Colombian - Caribbean coast. In 2014 she joined the Smithsonian Tropical Research Institute where she worked as a postdoctoral researcher studying the connectivity of "Isostichopus badionotus" populations. | https://en.wikipedia.org/wiki?curid=62393626 |
Scandian orogeny The was an orogeny mountain building event, preserved in the rocks of eastern Greenland, eastern Svalbard, northern Scotland and much of the coast of Norway. The orogeny occurred from 435 to 410 million years ago, as Baltica and Laurentia collided. The remnants of an ophiolite complex which was obducted eastward onto Baltica are located on southwest coast of Norway. The present of eclogite containing the mineral coesite indicates high pressure and high-temperature burial of Baltican rocks, as much as 80 to 100 kilometers deep. | https://en.wikipedia.org/wiki?curid=62395148 |
Boothite is a very rare, naturally occurring mineral containing hydrated copper sulphate. Discovered in Oakland California before 1959. | https://en.wikipedia.org/wiki?curid=62398982 |
Estudios Geológicos is a peer-reviewed open access scholarly journal publishing research articles and reviews in Earth Sciences. It is a journal operated by the Spanish National Research Council (CSIC), with the Geosciences Institute at the Complutense University of Madrid. The current executive editor is Jose María Cebriá Gómez. The journal is abstracted and indexed in: | https://en.wikipedia.org/wiki?curid=62406211 |
Jena glass (German: "Jenaer Glas") is a shock- and heat-resistant glass used in scientific and technological applications, especially in chemistry. The glass was invented by Otto Schott in 1884 in Jena, Germany, where he had established Schott AG with Ernst Abbe and Carl Zeiss. is a borosilicate which, in early manufacture, contained added aluminum, magnesium, sodium, and zinc. It was a predecessor to other borosilicate glasses which came into wide use in the twentieth century, such as Pyrex. | https://en.wikipedia.org/wiki?curid=62408275 |
Lopian orogeny The (also known as the Rebolian orogeny) was a mountain building event that affected the Baltic Shield during the Archean, between 2.9 and 2.6 billion years ago. The Kola-Belomorian gneiss and Karelian granitoid-greenstone terrane both formed during this time. | https://en.wikipedia.org/wiki?curid=62410585 |
Sven Gustaf Hedin (1859–1933) was a Swedish chemist and physiologist credited with the discovery of histidine. | https://en.wikipedia.org/wiki?curid=62419778 |
Perturbed angular correlation The perturbed γ-γ angular correlation, PAC for short or PAC-Spectroscopy, is a method of nuclear solid-state physics with which magnetic and electric fields in crystal structures can be measured. In doing so, electrical field gradients and the Larmor frequency in magnetic fields as well as dynamic effects are determined. With this very sensitive method, which requires only about 10-1000 billion atoms of a radioactive isotope per measurement, material properties in the local structure, phase transitions, magnetism and diffusion can be investigated. The PAC method is related to nuclear magnetic resonance and the Mössbauer effect, but shows no signal attenuation at very high temperatures. Today only the time-differential perturbed angular correlation (TDPAC) is used. PAC goes back to a theoretical work by Donald R. Hamilton from 1940. The first successful experiment was carried out by Brady and Deutsch in 1947. Essentially spin and parity of nuclear spins were investigated in these first PAC experiments. However, it was recognized early on that electric and magnetic fields interact with the nuclear moment, providing the basis for a new form of material investigation: nuclear solid-state spectroscopy. Step by step the theory was developed. After Abragam and Pound published their work on the theory of PAC in 1953 including extra nuclear fields, many studies with PAC were carried out afterwards | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation In the 1960s and 1970s, interest in PAC experiments sharply increased, focusing mainly on magnetic and electric fields in crystals into which the probe nuclei were introduced. In the mid-1960s, ion implantation was discovered, providing new opportunities for sample preparation. The rapid electronic development of the 1970s brought significant improvements in signal processing. From the 1980s to the present, PAC has emerged as an important method for the study and characterization of materials. B. for the study of semiconductor materials, intermetallic compounds, surfaces and interfaces. Lars Hemmingsen et al. Recently, PAC also applied in biological systems. While until about 2008 PAC instruments used conventional high-frequency electronics of the 1970s, in 2008 Christian Herden and Jens Röder et al. developed the first fully digitized PAC instrument that enables extensive data analysis and parallel use of multiple probes. Replicas and further developments followed. PAC uses radioactive probes, which have an intermediate state with decay times of 2 ns to approx. 10 μs, see example In in the picture on the right. After electron capture (EC), indium transmutates to cadmium. Immediately thereafter, the cadmium nucleus is predominantly in the excited 7/2+ nuclear spin and only to a very small extent in the 11/2- nuclear spin, the latter should not be considered further. The 7/2+ excited state transitions to the 5/2+ intermediate state by emitting a 171 keV γ-quantum. The intermediate state has a lifetime of 84 | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation 5 ns and is the sensitive state for the PAC. This state in turn decays into the 1/2+ ground state by emitting a γ-quantum with 245 keV. PAC now detects both γ-quanta and evaluates the first as a start signal, the second as a stop signal. Now one measures the time between start and stop for each event. This is called coincidence when a start and stop pair has been found. Since the intermediate state decays according to the laws of radioactive decay, one obtains an exponential curve with the lifetime of this intermediate state after plotting the frequency over time. Due to the non-spherically symmetric radiation of the second γ-quantum, the so-called anisotropy, which is an intrinsic property of the nucleus in this transition, it comes with the surrounding electrical and/or magnetic fields to a periodic disorder (hyperfine interaction). The illustration of the individual spectra on the right shows the effect of this disturbance as a wave pattern on the exponential decay of two detectors, one pair at 90° and one at 180° to each other. The waveforms to both detector pairs are shifted from each other. Very simply, one can imagine a fixed observer looking at a lighthouse whose light intensity periodically becomes lighter and darker. Correspondingly, a detector arrangement, usually four detectors in a planar 90 ° arrangement or six detectors in an octahedral arrangement, "sees" the rotation of the core on the order of magnitude of MHz to GHz | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation According to the number n of detectors, the number of individual spectra (z) results after z=n²-n, for n=4 therefore 12 and for n=6 thus 30. In order to obtain a PAC spectrum, the 90° and 180° single spectra are calculated in such a way that the exponential functions cancel each other out and, in addition, the different detector properties shorten themselves. The pure perturbation function remains, as shown in the example of a complex PAC spectrum. Its Fourier transform gives the transition frequencies as peaks. formula_1, the count rate ratio, is obtained from the single spectra by using: Depending on the spin of the intermediate state, a different number of transition frequencies show up. For 5/2 spin, 3 transition frequencies can be observed with the ratio ω+ω=ω. As a rule, a different combination of 3 frequencies can be observed for each associated site in the unit cell. PAC is a statistical method: Each radioactive probe atom sits in its own environment. In crystals, due to the high regularity of the arrangement of the atoms or ions, the environments are identical or very similar, so that probes on identical lattice sites experience the same hyperfine field or magnetic field, which then becomes measurable in a PAC spectrum. On the other hand, for probes in very different environments, such as in amorphous materials, a broad frequency distribution or no is usually observed and the PAC spectrum appears flat, without frequency response | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation With single crystals, depending on the orientation of the crystal to the detectors, certain transition frequencies can be reduced or extinct, as can be seen in the example of the PAC spectrum of zinc oxide (ZnO). In the typical PAC spectrometer, a setup of four 90° and 180° planar arrayed detectors or six octahedral arrayed detectors are placed around the radioactive source sample. The detectors used are scintillation crystals of BaF or NaI. For modern instruments today mainly LaBr:Ce or CeBr are used. Photomultipliers convert the weak flashes of light into electrical signals generated in the scintillator by gamma radiation. In classical instruments these signals are amplified and processed in logical AND/OR circuits in combination with time windows the different detector combinations (for 4 detectors: 12, 13, 14, 21, 23, 24, 31, 32, 34, 41, 42, 43) assigned and counted. Modern digital spectrometers use digitizer cards that directly use the signal and convert it into energy and time values and store them on hard drives. These are then searched by software for coincidences. Whereas in classical instruments, "windows" limiting the respective γ-energies must be set before processing, this is not necessary for the digital PAC during the recording of the measurement. The analysis only takes place in the second step | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation In the case of probes with complex cascades, this makes it makes it possible to perform a data optimization or to evaluate several cascades in parallel, as well as measuríng different probes simultaneously. The resulting data volumes can be between 60 and 300 GB per measurement. As materials for the investigation (samples) are in principle all materials that can be solid and liquid. Depending on the question and the purpose of the investigation, certain framework conditions arise. For the observation of clear perturbation frequencies it is necessary, due to the statistical method, that a certain proportion of the probe atoms are in a similar environment and e.g. experiences the same electric field gradient. Furthermore, during the time window between the start and stop, or approximately 5 half-lives of the intermediate state, the direction of the electric field gradient must not change. In liquids, therefore, no interference frequency can be measured as a result of the frequent collisions, unless the probe is complexed in large molecules, such as in proteins. The samples with proteins or peptides are usually frozen to improve the measurement. The most studied materials with PAC are solids such as semiconductors, metals, insulators, and various types of functional materials. For the investigations, these are usually crystalline. Amorphous materials do not have highly ordered structures. However, they have close proximity, which can be seen in PAC spectroscopy as a broad distribution of frequencies | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation Nano-materials have a crystalline core and a shell that has a rather amorphous structure. This is called core-shell model. The smaller the nanoparticle becomes, the larger the volume fraction of this amorphous portion becomes. In PAC measurements, this is shown by the decrease of the crystalline frequency component in a reduction of the amplitude (attenuation). The amount of suitable PAC isotopes required for a measurement is between about 10 to 1000 billion atoms (10-10). The right amount depends on the particular properties of the isotope. 10 billion atoms are a very small amount of substance. For comparison, one mol contains about 6.22x10 particles. 10 atoms in one cubic centimeter of beryllium give a concentration of about 8 nmol/L (nanomol=10 mol). The radioactive samples each have an activity of 0.1-5 MBq, which is in the order of the exemption limit for the respective isotope. How the PAC isotopes are brought into the sample to be examined is up to the experimenter and the technical possibilities. The following methods are usual: During implantation, a radioactive ion beam is generated, which is directed onto the sample material. Due to the kinetic energy of the ions (1-500 keV) these fly into the crystal lattice and are slowed down by impacts. They either come to a stop at interstitial sites or push a lattice-atom out of its place and replace it. This leads to a disruption of the crystal structure. These disorders can be investigated with PAC. By tempering these disturbances can be healed | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation If, on the other hand, radiation defects in the crystal and their healing are to be examined, unperseived samples are measured, which are then annealed step by step. The implantation is usually the method of choice, because it can be used to produce very well-defined samples. In a vacuum, the PAC probe can be evaporated onto the sample. The radioactive probe is applied to a hot plate or filament, where it is brought to the evaporation temperature and condensed on the opposite sample material. With this method, e.g. surfaces are examined. Furthermore, by vapor deposition of other materials, interfaces can be produced. They can be studied during tempering with PAC and their changes can be observed. Similarly, the PAC probe can be transferred to sputtering using a plasma. In the diffusion method, the radioactive probe is usually diluted in a solvent applied to the sample, dried and it is diffused into the material by tempering it. The solution with the radioactive probe should be as pure as possible, since all other substances can diffuse into the sample and affect thereby the measurement results. The sample should be sufficiently diluted in the sample. Therefore, the diffusion process should be planned so that a uniform distribution or sufficient penetration depth is achieved. PAC probes may also be added during the synthesis of sample materials to achieve the most uniform distribution in the sample | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation This method is particularly well suited if, for example, the PAC probe diffuses only poorly in the material and a higher concentration in grain boundaries is to be expected. Since only very small samples are necessary with PAC (about 5 mm), micro-reactors can be used. Ideally, the probe is added to the liquid phase of the sol-gel process or one of the later precursor phases. In neutron activation, the probe is prepared directly from the sample material by converting very small part of one of the elements of the sample material into the desired PAC probe or its parent isotope by neutron capture. As with implantation, radiation damage must be healed. This method is limited to sample materials containing elements from which neutron capture PAC probes can be made. Furthermore, samples can be intentionally contaminated with those elements that are to be activated. For example, hafnium is excellently suited for activation because of its large capture cross section for neutrons. Rarely used are direct nuclear reactions in which nuclei are converted into PAC probes by bombardment by high-energy elementary particles or protons. This causes major radiation damage, which must be healed. This method is used with PAD, which belongs to the PAC methods. The currently largest PAC laboratory in the world is located at ISOLDE in CERN with about 10 PAC instruments, that receives its major funding form BMBF | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation Radioactive ion beams are produced at the ISOLDE by bombarding protons from the booster onto target materials (uranium carbide, liquid tin, etc.) and evaporating the spallation products at high temperatures (up to 2000 °C), then ionizing them and then accelerating them. With the subsequent mass separation usually very pure isotope beams can be produced, which can be implanted in PAC samples. Of particular interest to the PAC are short-lived isomeric probes such as: Cd, Hg, Pb, and various rare earth probes. The first formula_3-quantum (formula_4) will be emitted isotopically. Detecting this quantum in a detector selects a subset with an orientation of the many possible directions that has a given. The second formula_3-quantum (formula_6) has an anisotropic emission and shows the effect of the angle correlation. The goal is to measure the relative probability formula_7 with the detection of formula_8 at the fixed angle formula_9 in relation to formula_10. The probability is given with the angle correlation (perturbation theory): For a formula_3-formula_3-cascade, formula_14 is due to the preservation of parity: Where formula_16 is the spin of the intermediate state and formula_17 with formula_18 the multipolarity of the two transitions. For pure multipole transitions, is formula_19. formula_20 is the anisotropy coefficient that depends on the angular momentum of the intermediate state and the multipolarities of the transition | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation The radioactive nucleus is built into the sample material and emits two formula_3-quanta upon decay. During the lifetime of the intermediate state, i.e. the time between formula_10 and formula_8, the core experiences a disturbance due to the hyperfine interaction through its electrical and magnetic environment. This disturbance changes the angular correlation to: formula_25 is the perturbation factor. Due to the electrical and magnetic interaction, the angular momentum of the intermediate state formula_17 experiences a torque about its axis of symmetry. Quantum-mechanically, this means that the interaction leads to transitions between the M states. The second formula_3-quantum (formula_8) is then sent from the intermediate level. This population change is the reason for the attenuation of the correlation. The interaction occurs between the magnetic core dipole moment formula_29 and the intermediate state formula_16 or/and an external magnetic field formula_31. The interaction also takes place between nuclear quadrupole moment and the off-core electric field gradient formula_32. For the magnetic dipole interaction, the frequency of the precession of the nuclear spin around the axis of the magnetic field formula_31 is given by: formula_36 is the Landé g-factor und formula_37 is the nuclear magneton | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation With formula_38 follows: From the general theory we get: For the magnetic interaction follows: The energy of the hyperfine electrical interaction between the charge distribution of the core and the extranuclear static electric field can be extended to multipoles. The monopole term only causes an energy shift and the dipole term disappears, so that the first relevant expansion term is the quadrupole term: This can be written as a product of the quadrupole moment formula_43 and the electric field gradient formula_44. Both [tensor]s are of second order. Higher orders have too small effect to be measured with PAC. The electric field gradient is the second derivative of the electric potential formula_45 at the core: formula_44 becomes diagonalized, that: The matrix is free of traces in the main axis system (Laplace equation) Typically, the electric field gradient is defined with the largest proportion formula_32 and formula_51: In cubic crystals, the axis parameters of the unit cell x, y, z are of the same length. Therefore: In axisymmetric systems is formula_55. For axially symmetric electric field gradients, the energy of the substates has the values: The energy difference between two substates, formula_58 and formula_59, is given by: The quadrupole frequency formula_61 is introduced. The formulas in the colored frames are important for the evaluation: The publications mostly list formula_64. formula_65 as elementary charge and formula_66 as Planck constant are well known or well defined | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation The nuclear quadrupole moment formula_67 is often determined only very inaccurately (often only with 2-3 digits). Because formula_64 can be determined much more accurately than formula_67, it is not useful to specify only formula_32 because of the error propagation. In addition, formula_64 is independent of spin! This means that measurements of two different isotopes of the same element can be compared, such as Hg(5/2−), Hg(5/2−) and Hg(9/2−). Further, formula_64 can be used as finger print method. For the energy difference then follows: If formula_55, then: with: For integer spins applies: For half integer spins applies: The perturbation factor is given by: With the factor for the probabilities of the observed frequencies: As far as the magnetic dipole interaction is concerned, the electrical quadrupole interaction also induces a precision of the angular correlation in time and this modulates the quadrupole interaction frequency. This frequency is an overlap of the different transition frequencies formula_83. The relative amplitudes of the various components depend on the orientation of the electric field gradient relative to the detectors (symmetry axis) and the asymmetry parameter formula_51. For a probe with different probe nuclei, one needs a parameter that allows a direct comparison: Therefore, the quadrupole coupling constant formula_64 independent of the nuclear spin formula_86 is introduced | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation If there is a magnetic and electrical interaction at the same time on the radioactive nucleus as described above, combined interactions result. This leads to the splitting of the respectively observed frequencies. The analysis may not be trivial due to the higher number of frequencies that must be allocated. These then depend in each case on the direction of the electric and magnetic field to each other in the crystal. PAC is one of the few ways in which these directions can be determined. If the hyperfine field fluctuates during the lifetime formula_87 of the intermediate level due to jumps of the probe into another lattice position or from jumps of a near atom into another lattice position, the correlation is lost. For the simple case with an undistorted lattice of cubic symmetry, for a jump rate of formula_88 for equivalent places formula_89, an exponential damping of the static formula_90-terms is observed: Here formula_93 is a constant to be determined, which should not be confused with the decay constant formula_94. For large values of formula_95, only pure exponential decay can be observed: The boundary case after Abragam-Pound is formula_93, if formula_98, then: Cores that transmute beforehand of the formula_3-formula_3-cascade usually cause a charge change in ionic crystals (In) to Cd). As a result, the lattice must respond to these changes. Defects or neighboring ions can also migrate | https://en.wikipedia.org/wiki?curid=62421802 |
Perturbed angular correlation Likewise, the high-energy transition process may cause the Auger effect, that can bring the core into higher ionization states. The normalization of the state of charge then depends on the conductivity of the material. In metals, the process takes place very quickly. This takes considerably longer in semiconductors and insulators. In all these processes, the hyperfine field changes. If this change falls within the formula_3-formula_3-cascade, it may be observed as an after effect. The number of nuclei in state (a) in the image on the right is depopulated both by the decay after state (b) and after state (c): mit: formula_105 From this one obtains the exponential case: For the total number of nuclei in the static state (c) follows: The initial occupation probabilities formula_108 are for static and dynamic environments: In the general theory for a transition formula_111 is given: with: | https://en.wikipedia.org/wiki?curid=62421802 |
Electrotaxis Electrotaxis, also known as galvanotaxis, is the directed motion of biological cells or organisms guided by an electric field or current. A wide variety of biological cells can naturally sense and follow DC electric fields. Such electric fields arise naturally in biological tissues during development and healing. In 1889, German physiologist Max Verworn applied a low-level direct current to a mixture of bacterial species and observed that some moved toward the anode and others moved to the cathode. Just two years later, in 1891, Belgian microscopist E. Dineur made the first known report of vertebrate cells migrating directionally in a direct current, a phenomenon which he coined galvanotaxis. Dineur used a zinc-copper cell to apply a constant current to the abdominal cavity of a frog via a pair of platinum electrodes. He found that inflammatory leukocytes aggregated at the negative electrode. Since these pioneering studies, a variety of different cell types and organisms have been shown to respond to electric fields. | https://en.wikipedia.org/wiki?curid=62437129 |
Rayner orogeny The was a mountain building that thickened the early continental crust (the cratonic nucleus) of what is now East Antarctica 3.5 billion years ago. Rocks preserving the orogeny are found in the rough vicinity of the Scott Mountains between Enderby Land in the north and Kemp Land in the south. | https://en.wikipedia.org/wiki?curid=62439166 |
Dabie-Sulu orogeny The also termed Qinling-Dabie-Sulu or Dabie Shan-Sulu was a mountain building event in the Triassic from 240 to 220 million years ago caused by the collision of the North China and South China cratons. It extends 2000 kilometers (1250 miles) from the Tanlu fault zone between Shanghai and Wuhan in modern-day China to the Qaidam basin north of the Tibetan Plateau. Typically 50 to 100 kilometers wide the orogeny contains the small South Qinling terrane. In fact, the Dabie-Sulu orogen is part of the larger Central China orogeny, extending through the Kunlun Range, Qinling Range, Tongbai-Dabie Range. Although it is offset by the Tan-Lu fault zone, it stretches through the Sulu region of the Shandong Peninsula and reaches South Korea. The orogeny is the largest area ultrahigh pressure metamorphic belt in the world. Low-temperature, but high-pressure conditions led rocks to reach eclogite-grade on the sequence of metamorphic facies. The added presence of diamonds and felsic gneiss indicates deep burial up to 100 kilometers below the surface. The China Continental Scientific Drilling Project was approved in China's ninth Five-Year Plan in 1997, with the CCSD-1 well inaugurated on 25 June 2001 drilling into the Dabie-Sulu orogen at Lianyungang City, Jiangsu Province. The goal of the project throughout the 2000s was to collect data about rheology and mantle mineralogy, as well as study processes similar to those in the center of the Himalayas, but at lower cost. | https://en.wikipedia.org/wiki?curid=62441248 |
Chonide orogeny The was a mountain building event in the Triassic preserved in coastal accretionary complexes in southwestern Chile. The Chonos Metamorphic Complex, Madre de Dios Accretionary Complex and Diego de Almagro Complex all outcrop west of the South Patagonian Batholith. Rocks in the Chonos Metamorphic Complex include turbidites as well meta-chert and mafic schist. Some researchers proposed that during the Permian, the supercontinent Gondwana moved rapidly northward leading to the formation of back-arc marginal basins. The closure of the basins then resulted in the orogeny. | https://en.wikipedia.org/wiki?curid=62441320 |
Insel orogeny The was a mountain building event in the late Archean, 2.65 billion years ago, in what is now Antarctica. First identified by geologists in Queen Maud Land and the southern Prince Charles Mountains, the orogeny produced rocks that reached amphibolite-grade on the sequence of metamorphic facies, produced large areas of new continental crust and altered the large areas of older rock. In the 1970s and 1980s, Antarctic researchers Grikurov and Elliot debated whether the Insel Orogeny marked the end of craton building in East Antarctica, or whether the process continued into the Proterozoic. | https://en.wikipedia.org/wiki?curid=62441360 |
Transamazonian orogeny The was a mountain building event in the Paleoproterozoic, affecting what is now the São Francisco Craton and Guyana Shield. During the orogeny from 2.14 to 1.94 billion years ago two small Archean proto-continents—including the greenstone belt-dominated Gavião Block and the calc-alkaline charnockite and enderbite-dominated Jequié Block—collided. The Contendas-Jacobina Lineament represents a suture zone where the collision occurred and the Gavião Block partially subducted under the Jequié Block. At the same time, another small continental fragment, the Serrinha Block, may have collided as well and was extensively reworked and metamorphosed, with orthogneiss and migmatite reaching amphibolite-grade on the sequence of metamorphic facies. The Serrinha Block is the basement rock of the Rio Itapicuru granite-greenstone belt. Several magmatic arcs formed between the colliding proto-continent blocks, including the Salvador-Curaçá Belt, Contendas-Mirante Belt, Jacobina-Mundo Novo Belt and Itabuna-Atlantic Belt. To the west of the Gavião Block, the Guanambi-Urandi Batholith formed with monzonite, granite intrusions and syenite, which was subsequently covered by Neoproterozoic sedimentary rocks. In the Guyana Shield, the resulted in refolding and reactivation of older tectonic features from the Guriense orogeny, producing horst and graben areas and intense pyroclastic ignimbrite and rhyolite eruptions. | https://en.wikipedia.org/wiki?curid=62445120 |
Early Ruker orogeny The was a mountain building event from 2.0 to 1.7 billion years ago in the Proterozoic and a key event in the assembly of Antarctica. Much of central Antarctica was added to the nucleus of the continent (in East Antarctica) during this time period. The event resulted in widespread formation of intra-cratonic miogeoclinal basins. Outcrops of rocks in the southern Prince Charles Mountains contain cross-bedded shale, sandstone, conglomerate, mudstone and ironstone. Many of these rocks were deformed and metamorphosed close to the end of the orogeny around 1.7 billion years ago. | https://en.wikipedia.org/wiki?curid=62445250 |
Late Ruker orogeny The also known as the Nimrod orogeny was a mountain building event around 1 billion years ago in the Proterozoic. Large portions of West Antarctica were added to the continent during this event. The orogeny was marked by subsidence, sedimentation and underwater volcanic eruptions along the proto-Pacific Ocean margin of proto-Antarctica. This melted some older igneous plutonic rocks and metamorphic rocks and caused some new metamorphism. Red beds were deposited and are now preserved in the Ritscher Upland of Queen Maud Land. Stromatolite carbonate beds and quartz arenite in the Shackleton Range serves as evidence for a stable platform and epicratonic sea during the period. | https://en.wikipedia.org/wiki?curid=62445321 |
Beardmore orogeny The was a mountain building event in the Neoproterozoic affecting what is now Antarctica. The event is preserved in the Trans-Antarctic Mountains, potentially in the Shackleton Range and by argillite-greywacke series in the Horlick Mountains, Queen Maud Land and the Thiel Mountains. Upright folds, asymmetric overturned or recumbent isoclinal folds first identified by Elliott in 1975 was interpreted in 1992 by Edmund Stump as indicative of compressive and convergent tectonic activity. The orogeny is expressed as an unconformity in the Transantarctic Mountains, between folded Late Proterozoic strata and overlying Early or Middle Cambrian sediments. This Late Precambrian event occurred between 660 and 580 Ma. | https://en.wikipedia.org/wiki?curid=62445379 |
Borchgrevink orogeny The also termed the Borchgrevink event is a proposed mountain building event in Antarctica in the Devonian and Silurian. The event is recorded by metamorphic rocks in Victoria Land as well as igneous and metamorphic rocks found throughout Marie Byrd Land, Thurston Island and the Antarctic Peninsula. More than other geological events in Antarctica, whether the Borchgrevink event constitutes an orogeny is a subject of debate among geologists. After initial radiometric dating indicated the event in the late 1960s and into the 1970s, a German expedition in 1981 failed to uncover evidence of deformation and compressional tectonics in North Victoria Land. | https://en.wikipedia.org/wiki?curid=62445437 |
Ross orogeny The was a mountain building event in Antarctica in the early Paleozoic. The ancestral (also termed proto-) Trans-Antarctic Mountains were uplifted earlier by the Beardmore orogeny but had eroded as a broad epicratonic sea flooded much of Antarctica in the Cambrian. Shallow water sedimentary rocks, platform carbonates and deepwater turbidites from this period are found in the mountain range. The was one of the most extensive orogenic events in Antarctica, causing widespread plutonism and metamorphism. Bimodal magmatism and extension mark the beginnings of the orogeny, while during the later phase sedimentary rocks at the continental margin were deformed, metamorphosed and intruded with granite batholiths. Interpretations of rock forms in Antarctica during the 1980s suggested a westward-dipping subduction zone may have formed along the paleo-Pacific Ocean shoreline of East Antarctica. This is inferred from a large number of I-type and S-type granitoids which are similar to large circum-Pacific batholiths. During the Late Cambrian to Early Ordovician, 450-520 Ma, Cambrian sediments within the Transantarctic Mountains were uplifted, folded, metamorphosed, and intruded by granitoid batholiths. Evidence of this origin may be found in the Shackleton Range, the Pensacola Mountains, Thiel Mountains, Horlick Mountains, and the Queen Maud Mountains. | https://en.wikipedia.org/wiki?curid=62445513 |
Ivanpah orogeny The was a mountain building event in the Proterozoic from 1.71 to 1.70 billion years ago, preserved in the Ivanpah Mountains and the rocks of some mountain ranges in western Arizona and eastern California. The event is closely related to the Yavapai orogeny and may have had the same underlying causes. Foliated intrusive rocks including granite-gneiss, augen gneiss as well as amphibolite and granulite-grade metamorphism on the sequence of metamorphic facies offers evidence about the extent of deformation. | https://en.wikipedia.org/wiki?curid=62445595 |
Great Falls orogeny The also termed Big Sky orogeny (in reference to its last phase found in the Tobacco Root Mountains) was a mountain building event in the Proterozoic preserved in what is now Montana and northwestern Wyoming. It is one of several orogenis involved in the assembly of the proto-North American continent Laurentia. Beginning around 1.86 billion years ago the Hearne craton and Wyoming craton began to migrate closer together with the closure of the Medicine Hat Ocean. In the main phase of the Great Falls orogeny, arc magmatism and anatexis occurred as the Montana metasedimentary terrane was buried beneath the Hearne craton (sometimes called the Medicine Hat-Hearne crust). The Big Sky orogeny refers to the last phase of the orogeny when the metasedimentary terrane was deformed, metamorphosed, melted and preserved in the Tobacco Root Mountains. | https://en.wikipedia.org/wiki?curid=62445686 |
Chemical gardening refers to the process of creating complex biological-looking structures by mixing chemicals together wherever large amounts of such chemicals naturally occur. More simply, forming natural minerals to mimic biology. For example, mixing iron-rich particles with alkaline liquids containing the chemicals silicate or carbonate have created biological-looking structures. Such structures are actually non-biological even though they may appear to be biological and/or fossils. According to researchers, "Chemical reactions like these have been studied for hundreds of years but they had not previously been shown to mimic these tiny iron-rich structures inside rocks. These results call for a re-examination of many ancient real-world examples to see if they are more likely to be fossils or non-biological mineral deposits." One use of the study of chemical gardening is to be better able to distinguish biological structures, including fossils, from non-biological structures on the planet Mars. | https://en.wikipedia.org/wiki?curid=62446002 |
Isan orogeny The affected the Mount Isa Inlier in what is now Australia between 1.65 and 1.50 billion years ago in the Proterozoic. Deformation from the event is widespread and complex in the Eastern Fold Belt, with no consensus on timing and sub-events as of 2017. To date, most research has focused on the Snake Creek Anticline, Selwyn zone and Mary Kathleen Domain. At the end of the orogeny, massive A-type granitoids intruded with the Williams-Naraku Batholith. | https://en.wikipedia.org/wiki?curid=62446333 |
Barramundi orogeny The was an orogenic event in what is now Australia between 1.88 and 1.84 billion years ago in the Proterozoic that affected Mount Isa and Pine Creek orogenic domains. Immediately before the orogeny, extension of Archean crust led to widespread basin formation. A large magmatic, granitoid forming event during the orogeny produced rocks with unusually similar chemistry. Other rocks include monzogranites, syenogranites, dacite and rhyolite rich in phenocrysts, ignimbrite sheets, and hornblende-tonalite. | https://en.wikipedia.org/wiki?curid=62446391 |
H2356-309 is a blazar (a type of active galactic nucleus) located behind the Sculptor Wall. Using the Chandra X-ray Observatory and the XMM-Newton, scientists have detected the warm-hot intergalactic medium (WHIM) between the galaxies in the Sculptor Wall. Scientists observed the absorption of a background light source in the warm-hot intergalactic medium. This background source is the blazer H2356-309. In data from the paper, CONFIRMATION OF X-RAY ABSORPTION BY WARM-HOT INTERGALACTIC MEDIUM IN THE SCULPTOR WALL, characteristics of this absorption in the sculptor wall by the oxygen atoms in particular, are similar to the absorption of the oxygen atoms in warm-hot intergalactic medium, giving scientists more assurance they can find other sources that compare to warm-hot intergalactic medium. There are also similarities in the predicted temperature and density of the warm-hot intergalactic medium compared to the Sculptor Wall. | https://en.wikipedia.org/wiki?curid=62448778 |
Eric Steig Eric Julian Steig is a Canadian-American glaciologist and geochemist who serves as professor of Earth and Space sciences at the University of Washington. He is also the founding co-director of ISOLAB and a founding member of RealClimate. In 2019, he was named a fellow of the American Association for the Advancement of Science. | https://en.wikipedia.org/wiki?curid=62449173 |
Dresden White Diamond The (also known as Dresden White or the Saxon White) is a cushion-cut diamond that probably originated from the Golconda mines in Southern India. The Dresden White's name is derived from Dresden, the capital city of Saxony, Germany, and from the gem's white color. When the diamond was first shown to Frederick Augustus I, the King of Saxony, he was so captivated by the cut, clarity, and color of the gem that he chose to acquire it at any cost. He supposedly paid somewhere between $750,000 and $1,000,000 for the diamond. In order to house his enormous collection of treasures, he set up the Green Vault in Dresden Castle. In 1746, goldsmith Jean Jacques Pallard designed the elaborate Golden Fleece ornament for Frederick Augustus and the Dresden White was placed at the top of the design. However, after the end of the Seven Years' War the Golden Fleece was broken up. The Dresden White was then incorporated into a shoulder knot ornament designed around 19 large diamonds and 216 small stones. After World War I, the items in the Green Vault were put on public display. They remained there until the beginning of World War II, when they were placed back under lock and key. At the height of the war in 1942, the items were transferred to the Königstein Fortress. In 1945, the Soviet Trophies Commission took the Green Vault contents to Moscow, but safely returned them in 1958. The contents were then placed on display in Dresden's Albertinium, which was built on the same site as the original Dresden museum | https://en.wikipedia.org/wiki?curid=62463264 |
Dresden White Diamond On November 25, 2019, a group of thieves stole much of the jewelry in the Green Vault during the 2019 Dresden heist, including the White Diamond. | https://en.wikipedia.org/wiki?curid=62463264 |
Phylogenetic classification of bony fishes The phylogenetic classification of bony fishes is a phylogenetic classification of bony fishes and is based on phylogenies inferred using molecular and genomic data for nearly 2000 fishes.. The first version was published in 2013 and resolved 66 orders. The latest version (version 4) was published in 2017 and recognised 72 orders and 79 suborders. The following cladograms show the phylogeny of the Osteichthyes down to order level, with the number of families in parentheses. The 43 orders of spiny-rayed fishes are related as follows: | https://en.wikipedia.org/wiki?curid=62464531 |
Anton Brugmans (1732–1789) was Dutch physicist who proposed a two-fluid theory of magnetism. He did magnetism experiments by putting objects on water or mercury, using surface tension to make them float and magnets to move them. He discovered the diamagnetism of bismuth. | https://en.wikipedia.org/wiki?curid=62491064 |
Robert R. L. Guillard (February 5, 1921 - September 25, 2016) was a scientist that contributed to the fields of aquaculture, oceanography, and phycology, particularly the phytoplankton. He earned his Ph.D. from Yale University. In 1958, he joined Woods Hole Oceanographic Institution as an associated scientist and later a senior scientist.. In 1982, he moved to Bigelow Laboratory for Ocean Sciences where he helped establish the Provasoli-Guillard National Center for Culture of Marine Phytoplankton (CCMP). He developed the algal culture medium, f/2, which is now commonly used for laboratory studies of marine algae. | https://en.wikipedia.org/wiki?curid=62502569 |
John T. Polhemus (11 September 1929 Ames, Iowa – 21 May 2013 Englewood, Colorado) was an American entomologist specialising in semi-aquatic Heteroptera. Polhemus wrote 288 peer-reviewed publications and described 474 species new to science. Polhemus was born in the American city of Ames, Iowa, the son of George and Elsie Polhemus. | https://en.wikipedia.org/wiki?curid=62508801 |
NGC 834 is a spiral galaxy located in the Andromeda constellation. It is estimated to be 160 million light-years away from the Milky Way galaxy and has a diameter of about 65,000 light-years. The object was discovered on September 21, 1786 by the astronomer William Herschel. | https://en.wikipedia.org/wiki?curid=62541187 |
NGC 874 is a spiral galaxy located in the Cetus constellation. It is estimated to be 572 million light-years away from the Milky Way galaxy and has a diameter of approximately 80,000 light-years. was discovered in 1886 by Frank Muller. | https://en.wikipedia.org/wiki?curid=62541410 |
NGC 740 is a barred spiral galaxy located in the Triangulum constellation. It is estimated to be 210 million light-years from the Milky Way and has a diameter of about 85,000 light-years. It was discovered by the Irish engineer Bindon Stoney, an assistant to William Parsons. | https://en.wikipedia.org/wiki?curid=62542493 |
NGC 1210 is a lenticular galaxy located in the constellation Fornax, about 177 million light years from the Milky Way. It was discovered by the American astronomer Ormond Stone in 1885. | https://en.wikipedia.org/wiki?curid=62543985 |
The Habitable Exoplanet Hunting Project is an international network of both professional and amateur astronomers created and coordinated by Alberto Caballero, an amateur astronomer and host of The Exoplanets Channel. As of December 2019, the network comprises 32 observatories located worldwide, including universities such as the University of South Africa, the University of Saskatchewan in Canada, and the California Polytechnic State University. The participants are searching for new potentially habitable exoplanets around non-flare G, K or M-type stars located within 100 light years. The initial list of targets consists of 10 stars that already have known transiting exoplanets outside the habitable zone. The network is monitoring 24/7 each star at a time during several months. Despite G and K-type stars are the main targets of the project, the team is initially focusing on red dwarfs because it take less time to discard the existence of potentially habitable exoplanets around these type of stars. Most of the observatories are able to detect transit depths as low as 0.1% and exoplanets with a radius of 0.7 Earth radii. To search for new exoplanets, the team is using two different methods: transit photometry and transit duration variation. Overall, the project is a new approach to the quest for exoplanets in which a large network of astronomers located in the five continents have the time to continuously observe each star individually during long periods of time in the search for dips in brightness produced by transiting exoplanets | https://en.wikipedia.org/wiki?curid=62558712 |
The Habitable Exoplanet Hunting Project As of December 2019, the network has already conducted observations on GJ 436 and GJ 1214, with a new campaign on GJ 3470 starting in January 2020. | https://en.wikipedia.org/wiki?curid=62558712 |
Ching-Liang Lin (; 22 January 1931 – 18 November 2019) was a Taiwanese physicist and professor at National Taiwan University. She was the first woman to be head of their department of physics She was born in 1931 in Takao Prefecture (present-day Kaoshiung). She graduated from Kaohsiung Municipal Kaohsiung Girls' Senior High School. She was a witness to the February 28 incident in 1947 which killed thousands in Taiwan and resulted in decades of martial law known as the White Terror. During this time, she chose to focus on the study of physics. She attended the University of Tokyo and was awarded a doctorate in physics in 1966. She returned to Taiwan in 1970 and was asked to create a physics department at Soowchow University. She married another academic, Feng Tsuan Hua, around 1972 and they left for a couple of years to work in Massachusetts in the United States at the University of Massachusetts, Amherst. She became a professor of physics at the National Taiwan University. From 1981 to 1983 she was the head of the department of physics at the university. As of 2019 she is the only woman to hold this role. Whilst she was in charge she arranged an audit of the department and it was found that a radioactive source that was meant to be stored safely was missing. The newspapers reported the problem and it was only when national bodies became involved that the radium - beryllium neutron source was found. She wanted to concentrate on teaching so she stood down from her management role | https://en.wikipedia.org/wiki?curid=62560284 |
Ching-Liang Lin She continued to teach for twenty years, and she was cited as a role model for other women to study physics. She retired and died in 2019 at National Taiwan University Hospital. In addition she has a large number of patents in her name. | https://en.wikipedia.org/wiki?curid=62560284 |
NGC 605 is a lenticular galaxy in the constellation Andromeda, which is about 234 million light-years from the Milky Way. It was discovered on October 21, 1881 by the French astronomer Édouard Jean-Marie Stephan. | https://en.wikipedia.org/wiki?curid=62564349 |
NGC 770 is an elliptical galaxy in the constellation Aries. It is around 120 million light years from the Milky Way and has a diameter of around . is gravitationally linked to NGC 772. The galaxy was discovered on November 3, 1855 by RJ Mitchell. | https://en.wikipedia.org/wiki?curid=62564371 |
NGC 690 is an intermediate spiral galaxy located in the constellation Cetus about 236 million light-years from the Milky Way. It was discovered by the American astronomer Francis Leavenworth in 1885. | https://en.wikipedia.org/wiki?curid=62565170 |
NGC 622 is a barred spiral galaxy located in the constellation Cetus about 234 million light-years from the Milky Way. It was discovered by British astronomer William Herschel in 1785. | https://en.wikipedia.org/wiki?curid=62565191 |
Irma Thesleff is a Professor Emerita at the University of Helsinki. Strome received a degree in dentistry from University of Helsinki and a Ph.D. in 1975, as well as post-graduate work at the National Institute of Dental Research, Bethesda. Thesleff has received several major science awards, served as president of the European Orthodontic Society and the Finnish Society for Developmental Biology. She is also an Academician of Science in Finland. Thesleff's work is in mammalian organs, and she is best known for studies on tissue interactions regulating tooth formation. This research has clinical implications for the diagnosis, prevention and treatment of congenital defects. Thesleff is a Foreign Associate of the United States National Academy of Sciences. | https://en.wikipedia.org/wiki?curid=62583732 |
Open Insulin Project The is a biohacking project to develop a free and open source procedure to produce insulin in an attempt to combat high prices for commercial insulin supplies. Set up in 2015, its collaborators include Counter Culture Labs, ReaGent and BioFoundry. The project aims to create a process to manufacture generic medical-grade insulin products that could then be approved by the FDA. | https://en.wikipedia.org/wiki?curid=62584569 |
Edwin Nicholas Arnold Edwin Nicholas "Nick" Arnold (b. 1940), is a British herpetologist and former Curator of Herpetology at the Natural History Museum, London. Arnold made seminal contributions to the herpetology of Europe and North Africa, especially on geckos and lizards of the family Lacertidae. He discovered and described 36 species and 4 subspecies of reptiles, and wrote "A Field Guide to the Reptiles and Amphibians of Britain and Europe", which appeared over multiple editions. At least four species of reptiles have been named in Arnold's honor: | https://en.wikipedia.org/wiki?curid=62592698 |
NGC 630 is an elliptical galaxy in the constellation Sculptor. It is estimated to be 275 million light years from the Milky Way and has a diameter of approximately 125,000 light years. The object was discovered on October 23, 1835 by the English astronomer John Herschel. | https://en.wikipedia.org/wiki?curid=62605727 |
KTHNY theory The KTHNY-theory describes melting of crystals in two dimensions (2D). The name is derived from the initials of the surnames of John Michael Kosterlitz, David J. Thouless, Bertrand Halperin, David R. Nelson, and A. Peter Young, who developed the theory in the 1970s. It is, beside the Ising model in 2D and the XY model in 2D, one of the few theories, which can be solved analytically and which predicts a phase transition at a temperature formula_1. Melting of 2D crystals is mediated by the dissociation of topological defects, which destroy the order of the crystal. In 2016, Michael Kosterlitz and David Thouless were awarded with the Nobel prize in physics for their idea, how thermally excited pairs of ``virtual´´ dislocations induce a softening (described by renormalization group theory) of the crystal during heating. The shear elasticity disappears simultaneously with the dissociation of the dislocations, indicating a fluid phase. Based on this work, David Nelson and Bertrand Halperin showed, that the resulting hexatic phase is not yet an isotropic fluid. Starting from a hexagonal crystal (which is the densest packed structure in 2D), the hexatic phase has a six-folded director field, similar to liquid crystals. Orientational order only disappears due to the dissociations of a second class of topological defects, named disclinations. Peter Young calculated the critical exponent of the diverging correlations length at the transition between crystalline and hexatic | https://en.wikipedia.org/wiki?curid=62606505 |
KTHNY theory predicts two continuous phase transitions, thus latent heat and phase coexistence is ruled out. The thermodynamic phases can be distinguished based on discrete versus continuous translational and orientational order. One of the transitions separates a solid phase with quasi-long range translational order and perfect long ranged orientational order from the hexatic phase. The hexatic phase shows short ranged translational order and quasi-long ranged orientational order. The second phase transition separates the hexatic phase from the isotropic fluid, where both, translational and orientational order is short ranged. The system is dominated by critical fluctuations, since for continuous transitions, the difference of energy between the thermodynamic phases disappears in the vicinity of the transition. This implies, that ordered and disordered regions fluctuate strongly in space and time. The size of those regions grows strongly near the transitions and diverges at the transition itself. At this point, the pattern of symmetry broken versus symmetric domains is fractal. Fractals are characterized by a scaling invariance – they appear similar on an arbitrary scale or by arbitrarily zooming in (this is true on any scale larger than the atomic distance). The scale invariance is the basis to use the renormalization group theory to describe the phase transitions. Both transitions are accompanied by spontaneous symmetry breaking | https://en.wikipedia.org/wiki?curid=62606505 |
KTHNY theory Unlike for melting in three dimensions, translational and orientational symmetry breaking does not need to appear simultaneously in 2D, since two different types of topological defects destroy the different types of order. Michael Kosterlitz and David Thouless tried to resolve a contradiction about 2D crystals: on one hand side, the Mermin-Wagner theorem claims that symmetry breaking of a continuous order-parameter cannot exist in two dimensions. This implies, that perfect long range positional order is ruled out in 2D crystals. On the other side, very early computer simulations of Berni Alder and Thomas E. Wainwright indicated crystallization in 2D. The shows implicitly that periodicity is not a sufficient criterion for a solid (this is already indicated by the existence of amorphous solids like glasses. Following M. Kosterlitz, a finite shear elasticity defines a 2D solid, including quasicrystals in this description. All three thermodynamic phases and their corresponding symmetries can be visualized using the structure factor :formula_2. The double sum runs over all positions of particle pairs I and j and the brackets denote an average about various configurations. The isotropic phase is characterized by concentric rings at formula_3, if formula_4 is the average particle distance calculated by the 2D particle density formula_5. The (closed packed) crystalline phase is characterized by six-fold symmetry based on the orientational order | https://en.wikipedia.org/wiki?curid=62606505 |
KTHNY theory Unlike in 3D, where the peaks are arbitrarily sharp (formula_6-peaks), the 2D peaks have a finite width described with a Lorenz-curve. This is due to the fact, that the translational order is only quasi-long ranged as predicted by the Mermin-Wagner theorem. The hexatic phase is characterized by six segments, which reflect the quasi-long ranged orientational order. The structure factor of Figure 1 is calculated from the positions of a colloidal monolayer (crosses at high intensity are artefacts from the Fourier transformation due to the finite (rectangular) field of view of the ensemble). To analyse melting due to the dissociation of dislocations, one starts with the energy formula_7 as function of distance between two dislocations. An isolated dislocation in 2D is a local distortions of the six-folded lattice, where neighbouring particles have five- and seven nearest neighbours, instead of six. It is important to note, that dislocations can only be created in pairs, due to topological reasons. A bound pair of dislocations is a local configuration with 5-7-7-5 neighbourhood. The double sum runs over all positions of defect pairs formula_9 and formula_10, formula_11 measures the distance between the dislocations. formula_12 is the Burgers vector and denotes the orientation of the dislocation at position Orte formula_13. The second term in the brackets brings dislocations to arrange preferentially antiparallel due to energetic reasons | https://en.wikipedia.org/wiki?curid=62606505 |
KTHNY theory Its contribution is small and can be neglected for large distance between defects. The main contribution stems from the logarithmic term (the first one in the brackets) which describes, how the energy of a dislocation pair diverges with increasing distance. Since the shortest distance between two dislocations is given approximatively by the average particle distance formula_14, the scaling of distances with formula_14 prevents the logarithm formula_16 to become negative. The strength of the interaction is proportional to Young's modulus formula_17 given by the stiffness of the crystal lattice. To create a dislocation from an undisturbed lattice, a small displacement on a scale smaller than the average particle distance formula_14 is needed. The discrete energy associated with this displacement is usually called core energy Energie formula_19 and has to be counted for each of the formula_20 dislocations individually (last term). An easy argument for the dominating logarithmic term is, that the magnitude of the strain induced by an isolated dislocation decays according mit formula_21 with distance. Assuming Hooke's approximation, the associated stress is linear with the strain. Integrating the strain ~1/r gives the energy proportional to the logarithm. The logarithmic distance dependence of the energy is the reason, why KTHNY-theory is one of the few theories of phase transitions which can be solved analytically: in statistical physics one has to calculate partition functions, e.g | https://en.wikipedia.org/wiki?curid=62606505 |
KTHNY theory the probability distribution for ``all´´ possible configurations of dislocation pairs given by the Boltzmann distribution formula_22. Here, formula_23 is the thermal energy with Boltzmann constant formula_24. For the majority of problems in statistical physics one can hardly solve the partition function due to the enormous amount of particles and degrees of freedoms. This is different in due to the logarithmic energy functions of dislocations formula_7 and the e-function from the Boltzmann factor as inverse which can be solved easily. We want to calculate the mean squared distance between two dislocations considering only the dominant logarithmic term for simplicity: This mean distance formula_27 tends to zero for low temparatures – dislocations will annihilate and the crystal is free of defects. The expression diverges formula_28, if the denominator tends to zero. This happens, when formula_29. A diverging distance of dislocations implies, that they are dissociated and do not form a bound pair. The crystal is molten, if several isolated dislocations are thermally excited and the melting temperature formula_30 is given by Young’s modulus: The dimensionless quantity formula_32 is a universal constant for melting in 2D and is independent of details of the system under investigation. This example investigated only an isolated pair of dislocations. In general, a multiplicity of dislocations will appear during melting | https://en.wikipedia.org/wiki?curid=62606505 |
KTHNY theory The strain field of an isolated dislocation will be shielded and the crystal will get softer in the vicinity of the phase transition; Young’s modulus will decrease due to dislocations. In KTHNY theory, this feedback of dislocations on elasticity, and especially on Young’s modulus acting as coupling constant in the energy function, is described within the framework of renormalization group theory. If a 2D crystal is heated, ``virtual´´ dislocation pairs will be excited due to thermal fluctuations in the vicinity of the phase transition. Virtual means, that the average thermal energy is not large enough to overcome (two times) the core-energy and to dissociate (unbind) dislocation pairs. Nonetheless, dislocation pairs can appear locally on very short time scales due to thermal fluctuations, before they annihilate again. Although they annihilate, they have a detectable impact on elasticity: they soften the crystal. The principle is completely analogue to calculating the bare charge of the electron in quantum electrodynamics (QED). In QED, the charge of the electron is shielded due to virtual electron-positron pairs due to quantum fluctuations of the vacuum. Roughly spoken one can summarize: If the crystal is softened due to the presence of virtual pairs of dislocation, the probability (fugacity) formula_33 for creating additional virtual dislocations is enhanced, proportional to the Boltzmann factor of the core-energy of a dislocation formula_34 | https://en.wikipedia.org/wiki?curid=62606505 |
KTHNY theory If additional (virtual) dislocations are present, the crystal will get additionally softer. If the crystal is additionally softer, the fugacity will increase further... and so on and so forth. David Nelson, Bertrand Halperin and independently Peter Young formulated this in a mathematically precise way, using renormalization group theory for the fugacity and the elasticity: In the vicinity of the continuous phase transition, the system becomes critical – this means that it becomes self-similar on all length scales formula_35. Executing a transformation of all length scales by an factor of formula_36, the energy formula_37 and fugacity formula_38 will depend on this factor, but the system has to appear identically, simultaneously due to the self similarity. Especially the energy function (Hamiltonian) of the dislocations have to be invariant in structure. The softening of the system after a length scale transformation (zooming out to visualize a larger area implies to count more dislocations) is now covered in a renormalized (reduced) elasticity. The recursion relation for elasticity and fugacity are: Similar recursion relations can be derived for the shear modulus and the bulk modulus. formula_41 and formula_42 are Bessel functions, respectively. Depending on the starting point, the recursion relation can run into two directions. formula_43 implies no defects, the ensemble is crystalline. formula_44, implies arbitrary many defects, the ensemble is fluid | https://en.wikipedia.org/wiki?curid=62606505 |
KTHNY theory The recursion relation have a fix-point at formula_45 with formula_46. Now, formula_47 is the renormalized value instead of the bare one. Figure 2 shows Youngs’modulus as function of the dimensionless control parameter formula_48. It measures the ratio of the repelling energy between two particles and the thermal energy (which was constant in this experiment). It can be interpreted as pressure or inverse temperature. The black curve is a thermodynamic calculation of a perfect hexagonal crystal at formula_49. The blue curve is from computer simulations and shows a reduced elasticity due to lattice vibrations at formula_50. The red curve is the renormalization following the recursion relations, Young's modulus disappears discontinuously to zero at formula_32. Turquoise symbols are from measurements of elasticity in a colloidal monolayer, and confirm the melting point at formula_52. The system enters the hexatic phase after the dissociation of dislocations. To reach the isotropic fluid, dislocations (5-7-pairs) have to dissociate into disclinations, consisting of isolated 5-folded and isolated 7-folded particles. Similar arguments for the interaction of disclinations compared to dislocations can be used. Again, disclinations can only be created as pairs due to topological reasons. Starting with the energy formula_53 as function of distance between two disclinations one finds: The logarithmic term is again dominating | https://en.wikipedia.org/wiki?curid=62606505 |
KTHNY theory The sign of the interaction gives attraction or repulsion for the winding numbers formula_55 and formula_56 of the five- and seven-folded disclinations in a way that ``charges´´ with opposite sign have attraction. The overall strength is given by the stiffness against twist. The coupling constant formula_57 is called Frank's constant, following the theory of liquid crystals. formula_58 is the discrete energy of a dislocation to dissociate into two disclinations. The squared distance of two disclinations can be calculated the same way, as for dislocations, only the prefactor, denoting the coupling constant, has to be changed accordingly. It diverges for formula_59. The system is molten from the hexatic phase into the isotropic liquid, if unbound disclinations are present. This transition temperature formula_60 is given by Frank's constant: formula_62 is again a universal constan. Figure 3 shows measurements of the orientational stiffness of a colloidal monolayer; Frank's constant drops below this universal constant at formula_60. Continuous phase transitions (or second order phase transition following Ehrenfest notation) show critical fluctuations of ordered and disordered regions in the vicinity of the transition. The correlation length measuring the size of those regions diverges algebraically in typical 3D systems. formula_64 Here, formula_65 is the transition temperature and formula_66 is a critical exponent | https://en.wikipedia.org/wiki?curid=62606505 |
KTHNY theory Another special feature of Kosterlitz–Thouless transitions is, that translational and orientational correlation length in 2D diverge exponentially (see also hexatic phase for the definition of those correlation functions): The critical exponent becomes formula_68 for the diverging translational correlation length at the hexatic – crystalline transition. D. Nelson and B. Halperin predicted, that Frank's constant diverges exponentially with formula_69 at formula_60, too. The red curve shows a fit of experimental data covering the critical behaviour; the critical exponent is measured to be formula_71. This value is compatible with the prediction of within the error bars. The orientational correlation length at the hexatic – isotropic transition is predicted to diverge with an exponent formula_72. This rational value is compatible with mean-field-theories and implies that a renormalization of Frank's constant is not necessary. The increasing shielding of orientational stiffness due to disclinations has not to be taken into account – this is already done by dislocations which are frequently present at formula_60. Experiments measured a critical exponent of formula_74. KTHNY-theory has been tested in experiment and in computer simulations. For short range particle interaction (hard discs), simulations found a weakly first order transition for the hexatic – isotropic transition, slightly beyond KTHNY-theory. | https://en.wikipedia.org/wiki?curid=62606505 |
Super-puff A super-puff is a type of exoplanet with a mass only a few times larger than Earth’s but a radius larger than Neptune, giving it a very low mean density. They are cooler and less massive than the inflated low-density hot-Jupiters. The most extreme examples known are the three planets around Kepler-51 which are all Jupiter-sized but with densities below 0.1 g/cm. These planets were discovered in 2012 but their low densities were not discovered until 2014. Another example is Kepler-87c. One hypothesis is that a super-puff has continuous outflows of dust to the top of its atmosphere (for example, Gliese 3470 b)- so the apparent surface is really dust at the top of the atmosphere. Another possibility is that some of the super-puff planets are smaller planets with large ring systems. | https://en.wikipedia.org/wiki?curid=62634082 |
HFE H63D gene mutation Homozygous mutations of HFE gene H63D are rarely the cause of hemochromatosis, however it is also associated with the occurrence of other conditions like hypotransferrinemia, liver dysfunction, bone and joint issues, diabetes mellitus, heart disease, hormone imbalances, porphyria cutanea tarda (PCT), infertility, stroke, neurodegenerative and brain damages, some cancers, venous and peripheral artery disease. The most relevant risk associated with a H63D mutation is for brain damage due to iron accumulation which causes oxidation processes within the affected cells (chronic oxidative stress) and, as a consequence, leading to cell death (scarring of brain tissue) with severely disturbed neurotransmitter activity. These incurable processes include increased cellular iron, oxidative stress (free radical activity), brain glutamate dysbalance, and abnormal levels of tau proteins and alpha-synuclein which both may result in dementias and parkinson’s disease, or similar conditions. Scientists found that patients homozygous for H63D show a higher risk of earlier signs of cognitive impairment and earlier onset of dementias compared to individuals with normal HFE genes or H63D heterozygous mutation. Some individuals with a homozygous H63D mutation may show signs of heart disease, cardiomyopathies and disturbances in the calcium channels in particular | https://en.wikipedia.org/wiki?curid=62635908 |
HFE H63D gene mutation A homozygous mutation of HFE gene H63D is an indication of an Iron Metabolism Disorder known as Hemochromatosis (Iron Overload) and may increase the risk to develop a fatty liver, cryptic (nonspecific) liver dysfunctions, metabolic syndrome and, in patients with a cirrhotic or a liver damaged due to alcohol also the rates of liver cancer. | https://en.wikipedia.org/wiki?curid=62635908 |
William M. Sinton (1925–2004) was a Harvard astronomer whose 1950s studies seemed to support the existence of Martian vegetation. A crater on Mars is named after him. | https://en.wikipedia.org/wiki?curid=62637695 |
NGC 880 is a spiral galaxy located in the constellation Cetus about 554 million light years from the Milky Way. It was discovered by the American astronomer Francis Leavenworth in 1886. | https://en.wikipedia.org/wiki?curid=62661221 |
Astronomy and spirituality have long been intertwined and closely related, mostly after their inception as mainstream subjects. When man started to take off the planet, psychological and cognitive changes were reported by people who directly interacted with outer space, either in visual manner or in exposure, demonstrated a quality of being furiously motivated and concerned about the Earth. | https://en.wikipedia.org/wiki?curid=62662353 |
Pavlova Corona is a corona found on the planet Venus, at , Mead Quadrangle. It is named after Anna Pavlova, a Russian ballerina (1881-1931). covers a circular area of around 400 km in diameter. is one of the four major coronae of eastern Eistla Regio (Didilia, Pavlova, Ninmah, and Isong). These coronae have relatively similar structure: an uplifted concentric feature with a central dome and surrounded by a relatively flat interior floor. | https://en.wikipedia.org/wiki?curid=62695989 |
Qiangtang terrane The Qiantang terrane is one of three main west-east-trending terranes of the Tibetan Plateau. During the Triassic, a southward-directed subduction along its northern margin resulted in the Jin-Shajing suture, the limit between it and the Songpan-Ganzi terrane. During the Jurassic, the Lhasa terrane merged with its southern margin along the Bangong suture. This suture, the closure of part of the Tethys Ocean, transformed the Qiantang terrane into a large-scale anticline. The Qiantang terrane is now located at above sea level, but the timing of this uplift remains debated, with estimates ranging from the Pliocene-Pleistocene (3–5 ) to the Eocene (35 Mya) when the plateau was first denudated. | https://en.wikipedia.org/wiki?curid=62713230 |
Der Naturforscher ( "The Naturalist") was a German scientific publication of the Enlightenment devoted to natural history. It was published yearly from 1774 to 1804, by J. J. Gebauers Witwe and Joh. Jac. Gebauer at Halle and edited first by Johann Ernst Immanuel Walch (from 1774 to 1778) and later by Johann Christian Daniel von Schreber (from 1779 to 1802). Both editors were also contributors. Most of the articles concern aspects of invertebrate zoology, mostly entomology and conchology. A few concern ornithology and other subjects, including mineralogy. It is usually bound in fifteen volumes octavo. Indices and registers are given at ten year intervals enumerating 640 memoirs. Just over 150 plates accompany the text. Many of the illustrations are by Johann Stephan Capieux and are of a very high standard. Armin Geus provides comprehensive indices. Most authors contributing to "Der Naturforscher" were German, but the journal also included some French authors. No natural history journal published in France existed at the time. Amongst others, some notable naturalists contributing to "Der Naturforscher" were: Claus Nissen described "Der Naturforscher" as "the most important 18th century German periodical for the descriptive natural sciences". Its taxonomic significance is considerable in entomology and conchology. Although many of the new species described here were subsequently considered junior synonyms, others remain valid | https://en.wikipedia.org/wiki?curid=62714068 |
Der Naturforscher Some of the valid species first described in "Der Naturforscher" are several well-known European Lepidoptera: "Lysandra bellargus" (Rottemburg, 1775), "Polyommatus icarus" (Rottemburg, 1775), "Zygaena lonicerae" (Scheven, 1777), "Paranthrene tabaniformis" (Rottemburg, 1775) and "Hyles gallii" (Rottemburg, 1775). Valid taxa in phylum Mollusca include "Turbo canaliculatus" Hermann, 1781, "Spondylus americanus" Hermann, 1781, "Modiolarca impacta" (Hermann, 1782) and "Semilimax semilimax" (J. Férussac, 1802). Although most ornithology articles are general or faunal lists, an exception exists in the first description of the wood warbler, "Phylloscopus sibilatrix" (Bechstein, 1793). Some exotic taxa were also first described in "Der Naturforscher", including the fish species "Sternoptyx diaphana" Hermann, 1781 and the Indomalayan butterfly "Euploea phaenareta" (Schaller, 1785). | https://en.wikipedia.org/wiki?curid=62714068 |
Shower (precipitation) A shower is a mode of precipitation characterized by an abrupt start and end and by rapid variations in intensity. Often strong and short-lived, it comes from convective clouds, like cumulus congestus. A shower will produce rain if the temperature is above the freezing point in the cloud, or snow/ice pellets/snow pellets if the temperature is below it at some point. In a meteorological observation, such as the METAR, they are noted SH giving respectively SHRA, SHSN, SHPE and SHGS. Convection occurs when the Earth's surface, especially within a conditionally unstable or moist atmosphere, becomes heated more than its surroundings and in turn leading to significant evaporation. The raised air parcel in a colder environment at altitude will cool but according to the adiabatic thermal gradient forming clouds, and later precipitation above the lifted condensation level (LCL). Depending of the Convective available potential energy (CAPE) available, the clouds will be cumulus humilis, cumulus mediocris and then cumulus congestus, the latter giving short-lived precipitation of rain, snow or ice pellets changing in intensity, i.e. showers. The life cycle of these clouds is fast because the updraft which forms them is most often cut-of by the descent of precipitation. In addition, these clouds flow with atmospheric circulation and spend little time above a point on the ground. This explains the variations in intensity and the short duration of the showers | https://en.wikipedia.org/wiki?curid=62714703 |
Shower (precipitation) The type of precipitation will depend on the temperature structure in the cloud and below it: If the convection is more intense, it leads to the formation of cumulonimbus clouds which have a very large vertical extension. This permits the displacement of electric charges from the bottom to the top that will create lightning and thunder. The showers associated with this kind of clouds is therefore called "thundershowers" or "thunderstorms". Hail and other violent phenomena are associated with this type of convection. Showers come from individual clouds as well as from groups of these. In mid-latitude regions, showers are often associated with cold fronts, often found along and behind it. However they can be in-bedded into a continuous rain episode when there is presence of band of conditional symmetric instability in an otherwise stable air mass. They can also be part of large convection zones called mesoscale convective system such as a squall line. | https://en.wikipedia.org/wiki?curid=62714703 |
Ellington (crater) Ellington is a crater on Mercury named after Duke Ellington, an American composer, pianist, and leader of a jazz orchestra. It was named by the IAU in 2012. Within Ellington is the smaller crater Berkel. The somewhat smaller crater Derain is to the northwest. | https://en.wikipedia.org/wiki?curid=62750078 |
Sadr al-Shari'a al-Asghar (), also known as Sadr al-Shari'a al-Thani (), was a Hanafi-Maturidi scholar, fakih (jurist), mutakallim (theologian), mufassir (Qur'anic exegete), muhaddis (expert of the Hadith), nahawi (grammarian), laghawi (linguist), logician, and astronomer, known for both his theories of time and place and his commentary on Islamic jurisprudence, indicating the depth of his knowledge in various Islamic disciplines. His lineage reaches 'Ubadah ibn al-Samit. He was praised by al-Taftazani, and 'Abd al-Hayy al-Lucknawi. He is 'Ubayd-Allah b. Mas'ud b. Mahmud b. Ahmad b. 'Ubayd-Allah al-Mahbubi al-Bukhari. He is also called Sadr al-Shari'a al-Asghar. Generally, when Sadr al-Shari'a is said, it refers to him. The term "al-Asghar" () or "al-Thani" () is sometimes added after his title to differentiate him from his great grandfather Ahmad b. 'Ubayd-Allah who is also known as Sadr al-Shari'a but with the suffix of "al-Akbar" () or "al-Awwal" (). His date of birth is not recorded in the well-known bio-dictionaries. He was born into a family with a long line of scholars. He studied under his father as well as his grandfather. His expertise expanded to many fields including Hadith, Fiqh, Usul al-Fiqh, kalam (theology), logic, grammar, rhetoric, exact and natural sciences. His knowledge was vast and incisive through which he was able to summarise many important and difficult topics succinctly. He authored of a number of influential works in the Hanafi madhhab | https://en.wikipedia.org/wiki?curid=62773262 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.