source
stringlengths 31
207
| text
stringlengths 12
1.5k
|
|---|---|
https://en.wikipedia.org/wiki/Laws%20of%20motion
|
In physics, a number of noted theories of the motion of objects have developed. Among the best known are:
Classical mechanics
Newton's laws of motion
Euler's laws of motion
Cauchy's equations of motion
Kepler's laws of planetary motion
General relativity
Special relativity
Quantum mechanics
Motion (physics)
|
https://en.wikipedia.org/wiki/Courant%20Institute%20of%20Mathematical%20Sciences
|
The Courant Institute of Mathematical Sciences (commonly known as Courant or CIMS) is the mathematics research school of New York University (NYU), and is among the most prestigious mathematics schools and mathematical sciences research centers in the world. Founded in 1935, it is named after Richard Courant, one of the founders of the Courant Institute and also a mathematics professor at New York University from 1936 to 1972, and serves as a center for research and advanced training in computer science and mathematics. It is located on Gould Plaza next to the Stern School of Business and the economics department of the College of Arts and Science.
NYU is ranked #1 in applied mathematics in the US (as per US News), #5 in citation impact worldwide, and #12 in citation worldwide. It is also ranked #19 worldwide in computer science and information systems. It is also known for its extensive research in pure mathematical areas, such as partial differential equations, probability and geometry, as well as applied mathematical areas, such as computational biology, computational neuroscience, and mathematical finance. The Mathematics Department of the institute has 15 members of the United States National Academy of Sciences (joint third globally with Princeton University, and after the University of California at Berkeley and Harvard University who are joint first globally with 17 members each, and just ahead of other topnotch research universities like Stanford University which ha
|
https://en.wikipedia.org/wiki/Blending%20inheritance
|
Blending inheritance is an obsolete theory in biology from the 19th century. The theory is that the progeny inherits any characteristic as the average of the parents' values of that characteristic. As an example of this, a crossing of a red flower variety with a white variety of the same species would yield pink-flowered offspring.
Charles Darwin's theory of inheritance by pangenesis, with contributions to egg or sperm from every part of the body, implied blending inheritance. His reliance on this mechanism led Fleeming Jenkin to attack Darwin's theory of natural selection on the grounds that blending inheritance would average out any novel beneficial characteristic before selection had time to act.
Blending inheritance was discarded with the general acceptance of particulate inheritance during the development of modern genetics, after .
History
Darwin's pangenesis
Charles Darwin developed his theory of evolution by natural selection on the basis of an understanding of uniform processes in geology, acting over very long periods of time on inheritable variation within populations. One of those processes was competition for resources, as Thomas Malthus had indicated, leading to a struggle to survive and to reproduce. Since some individuals would by chance have traits that allowed them to leave more offspring, those traits would tend to increase in the population. Darwin assembled many lines of evidence to show that variation occurred and that artificial selection by animal
|
https://en.wikipedia.org/wiki/Giuseppe%20Veronese
|
Giuseppe Veronese (7 May 1854 – 17 July 1917) was an Italian mathematician. He was born in Chioggia, near Venice.
Education
Veronese earned his laurea in mathematics from the Istituto Tecnico di Venezia in 1872.
Work
Although Veronese's work was severely criticised as unsound by Peano, he is now recognised as having priority on many ideas that have since become parts of transfinite numbers and model theory, and as one of the respected authorities of the time, his work served to focus Peano and others on the need for greater rigor.
He is particularly noted for his hypothesis of relative continuity which was the foundation for his development of the first non-Archimedean linear continuum.
Veronese produced several significant monographs. The most famous appeared in 1891, Fondamenti di geometria a più dimensioni e a più specie di unità rettilinee esposti in forma elementare, normally referred to as Fondamenti di geometria to distinguish it from Veronese' other works also styled Fondamenti. It was this work that was most severely criticised by both Peano and Cantor, however Levi-Civita described it as masterful and Hilbert as profound.
See also
Veronese surface
References
Philip Ehrlich (ed) Real Numbers, Generalisations of the Reals, and Theories of Continua, 1994.
Paola Cantu', Giuseppe Veronese e i fondamenti della geometria [Giuseppe Veronese and the Foundations of Geometry], Milano, Unicopli, "Biblioteca di cultura filosofica, 10", 1999, 270 pp. .
Philip Ehrlich: T
|
https://en.wikipedia.org/wiki/Hora%C8%9Biu%20N%C4%83stase
|
Horațiu Năstase is a Romanian physicist and professor in the string theory group at Instituto de Física Teórica of the São Paulo State University in São Paulo, Brazil.
He was born in Bucharest, Romania, and finished high school at the Nicolae Bălcescu High School (now Saint Sava National College). He did his undergraduate studies in the Physics Department of the University of Bucharest, graduating in 1995. His last year there he studied at the Niels Bohr Institute (NBI), Copenhagen University, with a scholarship which continued into the following year. In 1996 he joined the Physics Department of the State University of New York at Stony Brook from which he received his PhD in May 2000, with thesis written under the direction of Peter van Nieuwenhuizen. From 2000 to 2002 he was a postdoc at the Institute for Advanced Study in Princeton, after which he was an assistant research professor at Brown University until 2006. From 2007 to 2009 he was an assistant professor at the Global Edge Institute of the Tokyo Institute of Technology in Japan. Since 2010, Năstase holds a permanent position as assistant professor at IFT-UNESP in Brazil.
Năstase attracted some media attention in 2005 by arguing that string theory could be tested by the Relativistic Heavy Ion Collider, through the AdS/CFT correspondence. He is also known for his work in 2002 with David Berenstein and Juan Maldacena to investigate the duality between strings on pp-wave spacetime and "BMN operators" in supersymmetric
|
https://en.wikipedia.org/wiki/List%20of%20Welsh%20mathematicians
|
This is a list of Welsh mathematicians, who have contributed to the development of mathematics.
References
Chambers, Ll. G. Mathemategwyr Cymru (Mathematicians of Wales), Cyd Bwyllgor Addysg Cymru, 1994.
External links
Welsh scientists Mathematicians, Scientists and Inventors
Welsh
|
https://en.wikipedia.org/wiki/Quadrature%20%28geometry%29
|
In mathematics, particularly in geometry, quadrature (also called squaring) is a historical process of drawing a square with the same area as a given plane figure or computing the numerical value of that area. A classical example is the quadrature of the circle (or squaring the circle).
Quadrature problems served as one of the main sources of problems in the development of calculus. They introduce important topics in mathematical analysis.
History
Antiquity
Greek mathematicians understood the determination of an area of a figure as the process of geometrically constructing a square having the same area (squaring), thus the name quadrature for this process. The Greek geometers were not always successful (see squaring the circle), but they did carry out quadratures of some figures whose sides were not simply line segments, such as the lune of Hippocrates and the parabola. By a certain Greek tradition, these constructions had to be performed using only a compass and straightedge, though not all Greek mathematicians adhered to this dictum.
For a quadrature of a rectangle with the sides a and b it is necessary to construct a square with the side (the geometric mean of a and b). For this purpose it is possible to use the following: if one draws the circle with diameter made from joining line segments of lengths a and b, then the height (BH in the diagram) of the line segment drawn perpendicular to the diameter, from the point of their connection to the point where it crosses t
|
https://en.wikipedia.org/wiki/Sphaleron
|
A sphaleron ( "slippery") is a static (time-independent) solution to the electroweak field equations of the Standard Model of particle physics, and is involved in certain hypothetical processes that violate baryon and lepton numbers. Such processes cannot be represented by perturbative methods such as Feynman diagrams, and are therefore called non-perturbative. Geometrically, a sphaleron is a saddle point of the electroweak potential (in infinite-dimensional field space).
This saddle point rests at the top of a barrier between two different low-energy equilibria of a given system; the two equilibria are labeled with two different baryon numbers. One of the equilibria might consist of three baryons; the other, alternative, equilibrium for the same system might consist of three antileptons. In order to cross this barrier and change the baryon number, a system must either tunnel through the barrier (in which case the transition is an instanton-like process) or must for a reasonable period of time be brought up to a high enough energy that it can classically cross over the barrier (in which case the process is termed a "sphaleron" process and can be modeled with an eponymous sphaleron particle).
In both the instanton and sphaleron cases, the process can only convert groups of three baryons into three antileptons (or three antibaryons into three leptons) and vice versa. This violates conservation of baryon number and lepton number, but the difference B − L is conserved. The mini
|
https://en.wikipedia.org/wiki/Hexafluoro-2-propanol
|
Hexafluoroisopropanol, commonly abbreviated HFIP, is the organic compound with the formula (CF3)2CHOH. This fluoroalcohol finds use as solvent in organic chemistry. Hexafluoro-2-propanol is transparent to UV light with high density, low viscosity and low refractive index. It is a colorless, volatile liquid with a pungent odor.
Production
Hexafluoro-propan-2-ol is prepared from hexafluoropropylene through hexafluoroacetone, which is then hydrogenated.
(CF3)2CO + H2 → (CF3)2CHOH
Solvent properties
As a solvent, hexafluoro-2-propanol is polar and exhibits strong hydrogen bonding properties. Testament to the strength of its hydrogen-bonding tendency is the fact that its 1:1 complex with THF distills near 100 °C. It has a relatively high dielectric constant of 16.7. It is also relatively acidic, with a pKa of 8.3, comparable to that for phenol. It is classified as a hard Lewis acid and its acceptor properties are discussed in the ECW model.
Hexafluoro-propan-2-ol is a speciality solvent for organic synthesis, particularly for reactions involving oxidations and strong electrophiles. For example, HFIP enhances the reactivity of hydrogen peroxide as applied to Baeyer-Villiger oxidation of cyclic ketones. In another illustration of its use, HFIP is used as the solvent for Lewis-acid catalyzed ring opening of epoxides.
It has also found use in biochemistry to solubilize peptides and to monomerize β-sheet protein aggregates. Because of its acidity (pKa = 9.3), it can be used a
|
https://en.wikipedia.org/wiki/Jeremy%20Narby
|
Jeremy Narby (born 1959 in Montreal, Quebec) is a Canadian anthropologist and author.
In his books, Narby examines shamanism, molecular biology, and shamans' knowledge of botanics and biology through the use of entheogens across many cultures.
Early life and education
Narby was born in 1959 and grew up in Montreal, Quebec, and Switzerland. He studied history at the University of Kent at Canterbury.
He has a PhD in anthropology from Stanford University and spent time in the Peruvian Amazon undertaking his PhD research starting in 1984. During those years living with the Ashaninca, Narby catalogued indigenous uses of rainforest resources to help combat ecological destruction.
Career
Narby has written and edited five books, as well as sponsored an expedition to the rainforest for biologists and other scientists to examine indigenous knowledge systems and the utility of Ayahuasca in gaining knowledge. The resulting documentary film was Night of the Liana.
Since 1989, Narby has been working as the Amazonian projects director for the Swiss Non-governmental organization, Nouvelle Planète.
Narby and three molecular biologists feature in the documentary Night of the Liana that documents them revising the Peruvian Amazon to test hypothesis presented in Intelligence in Nature.
Books
The Cosmic Serpent
The Cosmic Serpent: DNA and the Origins of Knowledge, published in 1998 documents Narby's time researching, as part of his doctoral studies in the Pichis Valley of the Peruvian Am
|
https://en.wikipedia.org/wiki/Q-analog
|
In mathematics, a q-analog of a theorem, identity or expression is a generalization involving a new parameter q that returns the original theorem, identity or expression in the limit as . Typically, mathematicians are interested in q-analogs that arise naturally, rather than in arbitrarily contriving q-analogs of known results. The earliest q-analog studied in detail is the basic hypergeometric series, which was introduced in the 19th century.
q-analogs are most frequently studied in the mathematical fields of combinatorics and special functions. In these settings, the limit is often formal, as is often discrete-valued (for example, it may represent a prime power).
q-analogs find applications in a number of areas, including the study of fractals and multi-fractal measures, and expressions for the entropy of chaotic dynamical systems. The relationship to fractals and dynamical systems results from the fact that many fractal patterns have the symmetries of Fuchsian groups in general (see, for example Indra's pearls and the Apollonian gasket) and the modular group in particular. The connection passes through hyperbolic geometry and ergodic theory, where the elliptic integrals and modular forms play a prominent role; the q-series themselves are closely related to elliptic integrals.
q-analogs also appear in the study of quantum groups and in q-deformed superalgebras. The connection here is similar, in that much of string theory is set in the language of Riemann surfaces, r
|
https://en.wikipedia.org/wiki/Heinz%20Pagels
|
Heinz Rudolf Pagels (February 19, 1939 – July 23, 1988) was an American physicist, an associate professor of physics at Rockefeller University, the executive director and chief executive officer of the New York Academy of Sciences, and president of the International League for Human Rights. He wrote the popular science books The Cosmic Code (1982), Perfect Symmetry (1985), and The Dreams of Reason: The Computer and the Rise of the Sciences of Complexity (1988).
Early life
Pagels was a 1956 graduate of Woodberry Forest School in Virginia. The school awards The Heinz R. Pagels Jr. Physics Memorial Award each year to a graduating student who has demonstrated outstanding achievement in physics.
Career
Pagels obtained his PhD in elementary particle physics from Stanford University under the guidance of Sidney Drell. His technical work included the Physics Reports review articles Quantum Chromodynamics (with W.Marciano) and "Departures from Chiral Symmetry". A number of his published papers dealt with the source of the mass of elementary particles in quantum field theory, especially the Nambu–Goldstone realization of chiral symmetry breaking. He also published (with David Atkatz) a visionary paper entitled "Origin of the Universe as a quantum tunneling event" (1982) that prefigured later work done in the field. The list of his graduate students includes Dan Caldi, Saul Stokar and Seth Lloyd.
Personal life
Pagels was a critic of those he believed misrepresented the discoveries an
|
https://en.wikipedia.org/wiki/Arc%20elasticity
|
In mathematics and economics, the arc elasticity is the elasticity of one variable with respect to another between two given points. It is the ratio of the percentage change of one of the variables between the two points to the percentage change of the other variable. It contrasts with the point elasticity, which is the limit of the arc elasticity as the distance between the two points approaches zero and which hence is defined at a single point rather than for a pair of points.
Like the point elasticity, the arc elasticity can vary in value depending on the starting point. For example, the arc elasticity of supply of a product with respect to the product's price could be large when the starting and ending prices are both low, but could be small when they are both high.20%/10%=2
Formula
The y arc elasticity of x is defined as:
where the percentage change in going from point 1 to point 2 is usually calculated relative to the midpoint:
The use of the midpoint arc elasticity formula (with the midpoint used for the base of the change, rather than the initial point (x1, y1) which is used in almost all other contexts for calculating percentages) was advocated by R. G. D. Allen for use when x refers to the quantity of a good demanded or supplied and y refers to its price, due to the following properties: (1) it is symmetric with respect to the two prices and quantities, (2) it is independent of the units of measurement, and (3) it yields a value of unity if the total revenues (
|
https://en.wikipedia.org/wiki/Impulse
|
Impulse or Impulsive may refer to:
Science
Impulse (physics), in mechanics, the change of momentum of an object; the integral of a force with respect to time
Impulse noise (disambiguation)
Specific impulse, the change in momentum per unit mass of propellant of a propulsion system
Impulse function, a mathematical function of an infinitely high amplitude and infinitesimal duration
Impulse response, a system's output when presented with the impulse function in Electrical Engineering
Impulse (psychology), a wish or urge, particularly a sudden one
Impulsion, a thrust of a horse
Film and television
Impulse (1954 film), a thriller film starring Arthur Kennedy
Impulse (1974 film), a thriller film starring William Shatner
Impulse (1984 film), a science fiction film starring Meg Tilly and Tim Matheson
Impulse (1990 film), a thriller film starring Theresa Russell
Impulse (2008 film), a thriller film starring Angus Macfadyen
Impulse (2010 film), an apocalyptic thriller film starring Chris Masterson
Impulse (TV series), a 2018 American television series that streams on YouTube Premium
"Impulse" (Star Trek: Enterprise), a third-season episode of Star Trek: Enterprise
Impulse drive, a fictional form of propulsion in Star Trek
Print media
Impulse (German magazine), a German monthly magazine
Impulse (Steven Gould novel), a 2013 novel by Steven Gould
Impulse (Hopkins novel), a 2007 young adult verse novel by Ellen Hopkins
Impulse (Psionex), a Marvel Comics character by
|
https://en.wikipedia.org/wiki/Algebraic%20graph%20theory
|
Algebraic graph theory is a branch of mathematics in which algebraic methods are applied to problems about graphs. This is in contrast to geometric, combinatoric, or algorithmic approaches. There are three main branches of algebraic graph theory, involving the use of linear algebra, the use of group theory, and the study of graph invariants.
Branches of algebraic graph theory
Using linear algebra
The first branch of algebraic graph theory involves the study of graphs in connection with linear algebra. Especially, it studies the spectrum of the adjacency matrix, or the Laplacian matrix of a graph (this part of algebraic graph theory is also called spectral graph theory). For the Petersen graph, for example, the spectrum of the adjacency matrix is (−2, −2, −2, −2, 1, 1, 1, 1, 1, 3). Several theorems relate properties of the spectrum to other graph properties. As a simple example, a connected graph with diameter D will have at least D+1 distinct values in its spectrum. Aspects of graph spectra have been used in analysing the synchronizability of networks.
Using group theory
The second branch of algebraic graph theory involves the study of graphs in connection to group theory, particularly automorphism groups and geometric group theory. The focus is placed on various families of graphs based on symmetry (such as symmetric graphs, vertex-transitive graphs, edge-transitive graphs, distance-transitive graphs, distance-regular graphs, and strongly regular graphs), and on the
|
https://en.wikipedia.org/wiki/Strain%20energy
|
In physics, the elastic potential energy gained by a wire during elongation with a tensile (stretching) or compressive (contractile) force is called strain energy. For linearly elastic materials, strain energy is:
where is stress, is strain, is volume, and is Young's modulus:
Molecular strain
In a molecule, strain energy is released when the constituent atoms are allowed to rearrange themselves in a chemical reaction. The external work done on an elastic member in causing it to distort from its unstressed state is transformed into strain energy which is a form of potential energy. The strain energy in the form of elastic deformation is mostly recoverable in the form of mechanical work.
For example, the heat of combustion of cyclopropane (696 kJ/mol) is higher than that of propane (657 kJ/mol) for each additional CH2 unit. Compounds with unusually large strain energy include tetrahedranes, propellanes, cubane-type clusters, fenestranes and cyclophanes.
References
Chemical bonding
Structural analysis
|
https://en.wikipedia.org/wiki/Platonic%20hydrocarbon
|
In organic chemistry, a Platonic hydrocarbon is a hydrocarbon (molecule) whose structure matches one of the five Platonic solids, with carbon atoms replacing its vertices, carbon–carbon bonds replacing its edges, and hydrogen atoms as needed.
Not all Platonic solids have molecular hydrocarbon counterparts; those that do are the tetrahedron (tetrahedrane), the cube (cubane), and the dodecahedron (dodecahedrane).
Tetrahedrane
Tetrahedrane (C4H4) is a hypothetical compound. It has not yet been synthesized without substituents, but it is predicted to be kinetically stable in spite of its angle strain. Some stable derivatives, including tetra(tert-butyl)tetrahedrane (a hydrocarbon) and tetra(trimethylsilyl)tetrahedrane, have been produced.
Cubane
Cubane (C8H8) has been synthesized. Although it has high angle strain, cubane is kinetically stable, due to a lack of readily available decomposition paths.
Octahedrane
Angle strain would make an octahedron highly unstable due to inverted tetrahedral geometry at each vertex. There would also be no hydrogen atoms because four edges meet at each corner; thus, the hypothetical octahedrane molecule would be an allotrope of elemental carbon, C6, and not a hydrocarbon. The existence of octahedrane cannot be ruled out completely, although calculations have shown that it is unlikely.
Dodecahedrane
Dodecahedrane (C20H20) was first synthesized in 1982, and has minimal angle strain; the tetrahedral angle is 109.5° and the dodecahedral angle
|
https://en.wikipedia.org/wiki/Benjamin%20Alvord%20%28mathematician%29
|
Benjamin Alvord (August 18, 1813 – October 16, 1884) was an American soldier, mathematician, and botanist.
Early life and career
Alvord was born in Rutland, Vermont, where he developed an interest in nature. He attended the United States Military Academy and displayed a talent in mathematics. He graduated in 1833.
He was assigned to the 4th U.S. Infantry and participated in the Seminole Wars. He returned to West Point as an assistant professor of mathematics until 1839, when he was again assigned to the 4th Infantry. He spent 21 years of his military career with that regiment.
He was on frontier, garrison, and engineer duty until 1846, when he participated in the military occupation of the new state of Texas. Subsequently, he served during the Mexican–American War, being brevetted successively to captain and major for gallantry in a number of important battles, including the Battle of Palo Alto and the Battle of Resaca de la Palma. He served as General Riley's chief of staff to Major Folliott T. Lally's column on the march from Vera Cruz to Mexico City in 1847. He joined the Aztec Club of 1847 in 1871.
After the Mexican–American War, he went from line to staff when he was named paymaster and promoted to major. He was assigned to various posts and was sent with the 4th Infantry to the West Coast. He was the engineer in charge of building the military road in southern Oregon. He was then chief paymaster in Oregon from 1854 until 1862.
Civil War service
From 1862 to 1865, d
|
https://en.wikipedia.org/wiki/Jacek%20Karpi%C5%84ski
|
Jacek Karpiński (9 April 1927 21 February 2010) was a Polish pioneer in computer engineering and computer science.
During World War II, he was a soldier in the Batalion Zośka of the Polish Home Army, and was awarded multiple times with a Cross of Valour. He took part in Operation Kutschera (intelligence) and the Warsaw Uprising, where he was heavily wounded.
Later, he became a developer of one of the first machine learning algorithms, techniques for character and image recognition.
After receiving a UNESCO award in 1960, he travelled for several years around the academic centres in the United States, including MIT, Harvard, Caltech, and many others.
In 1971, he designed one of the first minicomputers, the K-202. Because of the policy on computer development in the People's Republic of Poland, belonging to the Comecon that time, the K-202 was never mass-produced.
Karpiński later became a pig farmer, and in 1981, after receiving a passport, emigrated to Switzerland.
He also founded the Laboratory for Artificial Intelligence of the Polish Academy of Sciences in the early 1960s.
Family and childhood
Jacek Karpiński was born on 9 April 1927 in Turin, Italy into a family of Polish intellectuals and alpinists. His father, Adam 'Akar' Karpiński, was a prominent aeronautic engineer (who co-constructed the SL-1 Akar, the first glider constructed entirely by the Poles) and inventor, credited with projects of innovative climbing equipment (crampons, 'Akar-Ramada' tent). His mothe
|
https://en.wikipedia.org/wiki/Woodstock%20of%20physics
|
The Woodstock of physics was the popular name given by physicists to the marathon session of the American Physical Society’s meeting on March 18, 1987, which featured 51 presentations of recent discoveries in the science of high-temperature superconductors. Various presenters anticipated that these new materials would soon result in revolutionary technological applications, but in the three subsequent decades, this proved to be overly optimistic. The name is a reference to the 1969 Woodstock Music and Art Festival.
Leading up to the meeting
Before a series of breakthroughs in the mid-1980s, most scientists believed that the extremely low temperature requirements of superconductors rendered them impractical for everyday use. However in June 1986, K. Alex Muller and Georg Bednorz working in IBM Zurich broke the record of critical temperature superconductivity in lanthanum barium copper oxide (LBCO) to 35 K above absolute zero, which had remained unbroken at 23 K for 17 years. Their discovery stimulated a great deal of additional research in high-temperature superconductivity.
By March 1987, a flurry of recent research on ceramic superconductors had succeeded in creating ever-higher superconducting temperatures, including the discovery of Maw-Kue Wu and Jim Ashburn at the University of Alabama, who found a critical temperature of 77 K in yttrium barium copper oxide (YBCO). This result was followed by Paul C. W. Chu at the University of Houston's of a superconductor that opera
|
https://en.wikipedia.org/wiki/Horst%20Ludwig%20St%C3%B6rmer
|
Horst Ludwig Störmer (; born April 6, 1949) is a German physicist, Nobel laureate and emeritus professor at Columbia University.
He was awarded the 1998 Nobel Prize in Physics jointly with Daniel Tsui and Robert Laughlin "for their discovery of a new form of quantum fluid with fractionally charged excitations" (the fractional quantum Hall effect). He and Tsui were working at Bell Labs at the time of the experiment cited by the Nobel committee.
Biography
Störmer was born in Frankfurt am Main, and grew up in the nearby town of Sprendlingen. After graduating from the Goetheschule in Neu-Isenburg in 1967, he enrolled in architectural engineering at the TH Darmstadt, but later moved to the Goethe University Frankfurt to study physics, but since he had missed the registration period for physics, he began with a mathematics and later changed to physics, qualifying for his Diploma in the laboratory of Werner Martienssen. Here he was supervised by Eckhardt Hoenig, and worked alongside another future Nobel laureate, Gerd Binnig.
Störmer moved to France to carry out his PhD research in Grenoble, working in a high-magnetic field laboratory which was run jointly between the French CNRS and the German Max Planck Institute for Solid State Research. Störmer's academic advisor was Hans-Joachim Queisser, and he was awarded a PhD by the University of Stuttgart in 1977 for his thesis on investigations of electron hole droplets subject to high magnetic fields. He also met his wife, Dominique
|
https://en.wikipedia.org/wiki/Mesoscale
|
Mesoscale may refer to:
Mesoscale meteorology
Mesoscopic scale in physics
Mesoscale manufacturing
Mesoscale eddies
|
https://en.wikipedia.org/wiki/Not%20in%20Our%20Genes
|
Not in Our Genes: Biology, Ideology and Human Nature is a 1984 book by the evolutionary geneticist Richard Lewontin, the neurobiologist Steven Rose, and the psychologist Leon Kamin, in which the authors criticize sociobiology and genetic determinism and advocate a socialist society. Its themes include the relationship between biology and society, the nature versus nurture debate, and the intersection of science and ideology.
The book formed part of a larger campaign against sociobiology. Its authors were praised for their criticism of IQ testing and were complimented by some for their critique of sociobiology. However, they have been criticized for misrepresenting the views of scientists such as the biologist E. O. Wilson and the ethologist Richard Dawkins, for using “determinism” and “reductionism” simply as terms of abuse, and for the influence of Marxism on their views. Critics have seen its authors' conclusions as political rather than scientific.
Summary
Lewontin, Rose and Kamin identify themselves as "respectively an evolutionary geneticist, a neurobiologist, and a psychologist." They criticize biological determinism and reductionism, and state that they share a commitment to the creation of a socialist society and a recognition that "a critical science is an integral part of the struggle to create that society". Their understanding of science draws on ideas suggested by Karl Marx and Friedrich Engels and developed by Marxist scholars in the 1930s. They also draw on t
|
https://en.wikipedia.org/wiki/Siemens-Schuckert
|
Siemens-Schuckert (or Siemens-Schuckertwerke) was a German electrical engineering company headquartered in Berlin, Erlangen and Nuremberg that was incorporated into the Siemens AG in 1966.
Siemens Schuckert was founded in 1903 when Siemens & Halske acquired Schuckertwerke. Subsequently, Siemens & Halske specialized in communications engineering and Siemens-Schuckert in power engineering and pneumatic instrumentation. During World War I Siemens-Schuckert also produced aircraft. It took over manufacturing of the renowned Protos vehicles in 1908. In World War II, the company had a factory producing aircraft and other parts at Monowitz near Auschwitz. There was a workers camp near the factory known as Bobrek concentration camp.
The Siemens Schuckert logo consisted of an S with a smaller S superimposed on the middle with the smaller S rotated left by 45 degrees. The logo was used into the late 1960s, when both companies merged with the Siemens-Reiniger-Werke AG to form the present-day Siemens AG.
Aircraft
Siemens-Schuckert built a number of designs in World War I and inter-war era. They also produced aircraft engines under the Siemens-Halske brand, which evolved into their major product line after the end of World War I. The company reorganized as Brandenburgische Motorenwerke, or simply Bramo, in 1936, and were later purchased in 1939 by BMW to become BMW Flugmotorenbau.
WW I
Siemens-Schuckert designed a number of heavy bombers early in World War I, building a run of seven Ri
|
https://en.wikipedia.org/wiki/Jochen%20Liedtke
|
Jochen Liedtke (26 May 1953 – 10 June 2001) was a German computer scientist, noted for his work on microkernel operating systems, especially in creating the L4 microkernel family.
Career
Education
In the mid-1970s Liedtke studied for a diploma degree in mathematics at the Bielefeld University. His thesis project was to build a compiler for the programming language ELAN, which had been launched for teaching programming in German schools. The compiler was written in ELAN.
Post grad
After his graduation in 1977, he remained at Bielefeld and worked on an Elan environment for the Zilog Z80 microprocessor. This required a runtime system (environment), which he named Eumel ("Extendable Multiuser Microprocessor ELAN-System", but also a colloquial north-German term for a likeable fool). Eumel grew into a complete multi-tasking, multi-user operating system supporting orthogonal persistence, which started shipping (by whom? to whom?) in 1980 and was later ported to Zilog Z8000, Motorola 68000 and Intel 8086 processors. As these processors lacked memory protection, Eumel implemented a virtual machine which added the features missing from the hardware. More than 2000 Eumel systems shipped, mostly to schools, and some to legal practices as a text processing platform.
In 1984, he joined the (GMD), the German National Research Center for Computer Science, which is now a part of the Fraunhofer Society. There, he continued his work on Eumel. In 1987, when microprocessors supporting virt
|
https://en.wikipedia.org/wiki/Interactive%20computing
|
In computer science, interactive computing refers to software which accepts input from the user as it runs.
Interactive software includes commonly used programs, such as word processors or spreadsheet applications. By comparison, non-interactive programs operate without user intervention; examples of these include compilers and batch processing applications that are pre-programmed to run independently.
Interactive computing focuses on real-time interaction ("dialog") between the computer and the operator, and the technologies that enable them.
If the response of the computer system is complex enough, it is said that the system is conducting social interaction; some systems try to achieve this through the implementation of social interfaces.
The nature of interactive computing as well as its impact on users, are studied extensively in the field of computer interaction.
History of interactive computing systems
Ivan Sutherland is considered the father of interactive computing for his work on Sketchpad, the interactive display graphics program he developed in 1963. He later worked at the ARPA Information Processing Techniques Office under the direction of J. C. R. Licklider.
There he facilitated ARPA's research grant to Douglas Engelbart for developing the NLS system at SRI, based on his visionary manifesto published in a 1962 report, in which Engelbart envisioned interactive computing as a vehicle for user interaction with computers, with each other, and with their knowle
|
https://en.wikipedia.org/wiki/Segre%20embedding
|
In mathematics, the Segre embedding is used in projective geometry to consider the cartesian product (of sets) of two projective spaces as a projective variety. It is named after Corrado Segre.
Definition
The Segre map may be defined as the map
taking a pair of points to their product
(the XiYj are taken in lexicographical order).
Here, and are projective vector spaces over some arbitrary field, and the notation
is that of homogeneous coordinates on the space. The image of the map is a variety, called a Segre variety. It is sometimes written as .
Discussion
In the language of linear algebra, for given vector spaces U and V over the same field K, there is a natural way to map their cartesian product to their tensor product.
In general, this need not be injective because, for , and any nonzero ,
Considering the underlying projective spaces P(U) and P(V), this mapping becomes a morphism of varieties
This is not only injective in the set-theoretic sense: it is a closed immersion in the sense of algebraic geometry. That is, one can give a set of equations for the image. Except for notational trouble, it is easy to say what such equations are: they express two ways of factoring products of coordinates from the tensor product, obtained in two different ways as something from U times something from V.
This mapping or morphism σ is the Segre embedding. Counting dimensions, it shows how the product of projective spaces of dimensions m and n embeds in dimension
C
|
https://en.wikipedia.org/wiki/Ozonolysis
|
In organic chemistry, ozonolysis is an organic reaction where the unsaturated bonds are cleaved with ozone (). Multiple carbon–carbon bond are replaced by carbonyl () groups, such as aldehydes, ketones, and carboxylic acids. The reaction is predominantly applied to alkenes, but alkynes and azo compounds are also susceptible to cleavage. The outcome of the reaction depends on the type of multiple bond being oxidized and the work-up conditions.
Detailed procedures have been reported.
Ozonolysis of alkenes
Alkenes can be oxidized with ozone to form alcohols, aldehydes or ketones, or carboxylic acids. In a typical procedure, ozone is bubbled through a solution of the alkene in methanol at −78 °C until the solution takes on a characteristic blue color, which is due to unreacted ozone. Industry however recommends temperatures near -20 °C. This color change indicates complete consumption of the alkene. Alternatively, various other reagents can be used as indicators of this endpoint by detecting the presence of ozone. If ozonolysis is performed by introducing a stream of ozone-enriched oxygen through the reaction mixture, the effluent gas can be directed through a potassium iodide solution. When the solution has stopped absorbing ozone, the excess ozone oxidizes the iodide to iodine, which can easily be observed by its violet color. For closer control of the reaction itself, an indicator such as Sudan Red III can be added to the reaction mixture. Ozone reacts with this indicat
|
https://en.wikipedia.org/wiki/CAR%20T%20cell
|
In biology, chimeric antigen receptors (CARs)—also known as chimeric immunoreceptors, chimeric T cell receptors or artificial T cell receptors—are receptor proteins that have been engineered to give T cells the new ability to target a specific antigen. The receptors are chimeric in that they combine both antigen-binding and T cell activating functions into a single receptor.
CAR T cell therapy uses T cells engineered with CARs to treat cancer. The premise of CAR-T immunotherapy is to modify T cells to recognize cancer cells in order to more effectively target and destroy them. Scientists harvest T cells from people, genetically alter them, then infuse the resulting CAR T cells into patients to attack their tumors.
CAR T cells can be derived either from T cells in a patient's own blood (autologously) or from the T cells of another, healthy, donor (allogeneically). Once isolated from a person, these T cells are genetically engineered to express a specific CAR, using a vector derived from an engineered lentivirus such as HIV (see Lentiviral vector in gene therapy). The CAR programs the recipient's T cells to target an antigen that is present on the surface of tumors. For safety, CAR T cells are engineered to be specific to an antigen that is expressed on a tumor but is not expressed on healthy cells.
After CAR T cells are infused into a patient, they act as a "living drug" against cancer cells. When they come in contact with their targeted antigen on a cell's surface, CAR T c
|
https://en.wikipedia.org/wiki/Bottomness
|
In physics, bottomness (symbol B′ using a prime as plain B is used already for baryon number) or beauty is a flavour quantum number reflecting the difference between the number of bottom antiquarks (n) and the number of bottom quarks (n) that are present in a particle:
Bottom quarks have (by convention) a bottomness of −1 while bottom antiquarks have a bottomness of +1. The convention is that the flavour quantum number sign for the quark is the same as the sign of the electric charge (symbol Q) of that quark (in this case, Q = −).
As with other flavour-related quantum numbers, bottomness is preserved under strong and electromagnetic interactions, but not under weak interactions. For first-order weak reactions, it holds that .
This term is rarely used. Most physicists simply refer to "the number of bottom quarks" and "the number of bottom antiquarks".
References
Quarks
Flavour (particle physics)
|
https://en.wikipedia.org/wiki/Charles%20H.%20Bennett%20%28physicist%29
|
Charles Henry Bennett (born 1943) is a physicist, information theorist and IBM Fellow at IBM Research. Bennett's recent work at IBM has concentrated on a re-examination of the physical basis of information, applying quantum physics to the problems surrounding information exchange. He has played a major role in elucidating the interconnections between physics and information, particularly in the realm of quantum computation, but also in cellular automata and reversible computing. He discovered, with Gilles Brassard, the concept of quantum cryptography and is one of the founding fathers of modern quantum information theory (see Bennett's four laws of quantum information).
Early career
Born in 1943 in New York City, Bennett earned a B.S. in chemistry from Brandeis University in 1964 and received his PhD from Harvard in 1970 for molecular-dynamics studies (computer simulation of molecular motion) under David Turnbull and Berni Alder. At Harvard, he also worked for James Watson one year as a teaching assistant about the genetic code. For the next two years he continued this research under Aneesur Rahman at Argonne National Laboratory (operated by the University of Chicago).
After joining IBM Research in 1972, he built on the work of IBM's Rolf Landauer to show that general-purpose computation can be performed by a logically and thermodynamically reversible apparatus; and in 1982 he proposed a re-interpretation of Maxwell's demon, attributing its inability to break the second law
|
https://en.wikipedia.org/wiki/List%20of%20United%20States%20regional%20mathematics%20competitions
|
Many math competitions in the United States have regional restrictions. Of these, most are statewide.
For a more complete list, please visit here .
The contests include:
Alabama
Alabama Statewide High School Mathematics Contest
Virgil Grissom High School Math Tournament
Vestavia Hills High School Math Tournament
Arizona
Great Plains Math League
AATM State High School Contest
California
Bay Area Math Olympiad
Lawrence Livermore National Laboratories Annual High School Math Challenge
Cal Poly Math Contest and Trimathlon
Polya Competition
Bay Area Math Meet
College of Creative Studies Math Competition
LA Math Cup
Math Day at the Beach hosted by CSULB
Math Field Day for San Diego Middle Schools
Mesa Day Math Contest at UC Berkeley
Santa Barbara County Math Superbowl
Pomona College Mathematical Talent Search
Redwood Empire Mathematics Tournament hosted by Humboldt State (middle and high school)
San Diego Math League and San Diego Math Olympiad hosted by the San Diego Math Circle
Santa Clara University High School Mathematics Contest
SC Mathematics Competition (SCMC) hosted by RSO@USC
Stanford Mathematics Tournament
UCSD/GSDMC High School Honors Mathematics Contest
Colorado
Colorado Mathematics Olympiad
District of Columbia
Moody's Mega Math
Florida
Florida-Stuyvesant Alumni Mathematics Competition
David Essner Mathematics Competition
James S. Rickards High School Fall Invitational
FAMAT Regional Competitions:
January Regional
February Region
|
https://en.wikipedia.org/wiki/Weak%20hypercharge
|
In the Standard Model of electroweak interactions of particle physics, the weak hypercharge is a quantum number relating the electric charge and the third component of weak isospin. It is frequently denoted and corresponds to the gauge symmetry U(1).
It is conserved (only terms that are overall weak-hypercharge neutral are allowed in the Lagrangian). However, one of the interactions is with the Higgs field. Since the Higgs field vacuum expectation value is nonzero, particles interact with this field all the time even in vacuum. This changes their weak hypercharge (and weak isospin ). Only a specific combination of them, (electric charge), is conserved.
Mathematically, weak hypercharge appears similar to the Gell-Mann–Nishijima formula for the hypercharge of strong interactions (which is not conserved in weak interactions and is zero for leptons).
In the electroweak theory SU(2) transformations commute with U(1) transformations by definition and therefore U(1) charges for the elements of the SU(2) doublet (for example lefthanded up and down quarks) have to be equal. This is why U(1) cannot be identified with U(1)em and weak hypercharge has to be introduced.
Weak hypercharge was first introduced by Sheldon Glashow in 1961.
Definition
Weak hypercharge is the generator of the U(1) component of the electroweak gauge group, and its associated quantum field mixes with the electroweak quantum field to produce the observed gauge boson and the photon of quantum electrodynami
|
https://en.wikipedia.org/wiki/Weak%20isospin
|
In particle physics, weak isospin is a quantum number relating to the electrically charged part of the weak interaction: Particles with half-integer weak isospin can interact with the bosons; particles with zero weak isospin do not.
Weak isospin is a construct parallel to the idea of isospin under the strong interaction. Weak isospin is usually given the symbol or , with the third component written as or .
It can be understood as the eigenvalue of a charge operator.
is more important than ; typically "weak isospin" is used as short form of the proper term "3rd component of weak isospin".
The weak isospin conservation law relates to the conservation of weak interactions conserve . It is also conserved by the electromagnetic and strong interactions. However, interaction with the Higgs field does not conserve , as directly seen by propagation of fermions, mixing chiralities by dint of their mass terms resulting from their Higgs couplings. Since the Higgs field vacuum expectation value is nonzero, particles interact with this field all the time even in vacuum. Interaction with the Higgs field changes particles' weak isospin (and weak hypercharge). Only a specific combination of them, (electric charge), is conserved.
Relation with chirality
Fermions with negative chirality (also called "left-handed" fermions) have and can be grouped into doublets with that behave the same way under the weak interaction. By convention, electrically charged fermions are assigned with the
|
https://en.wikipedia.org/wiki/Besant%20Hill%20School
|
Besant Hill School of Happy Valley, formerly the Happy Valley School, is an American private, coeducational boarding school and day school in Ojai, California. Notable subjects are environmental science and sustainability program coupled with a working garden/farm on campus. The school has approximately 100 students and about 35 faculty and staff, all of whom live on or near campus. There were 13 states and 22 countries represented in the 2017-2018 student body
History
The school was conceptualized by Annie Besant, who had initially envisioned an educational community that would nurture spiritual, artistic, and intellectual growth as well as physical and mental well-being. Initially a secondary school, it was founded by Guido Ferrando, Aldous Huxley, J. Krishnamurti, and Rosalind Rajagopal. The school opened on October 1, 1946, as the Happy Valley School, with Dr. Ferrando serving as the first Head of the School. It sat on of land that was bought in 1927 by Besant. It was later renamed in July 2007 in Besant's honor.
Notable founders/faculty members
Annie Besant – Main Founder of the school, women's rights activist, and president of the theosophical society.
Rosalind Rajagopal – Main Founder of the school and long-time director.
Aldous Huxley – Main Founder of the school and author/novelist.
Jiddu Krishnamurti – Writer on philosophical and spiritual subjects.
Franklin Lacey – Faculty member, Former Head of School, playwright and screenwriter.
Beatrice Wood – Faculty member
|
https://en.wikipedia.org/wiki/Fuzzy%20measure%20theory
|
In mathematics, fuzzy measure theory considers generalized measures in which the additive property is replaced by the weaker property of monotonicity. The central concept of fuzzy measure theory is the fuzzy measure (also capacity, see ), which was introduced by Choquet in 1953 and independently defined by Sugeno in 1974 in the context of fuzzy integrals. There exists a number of different classes of fuzzy measures including plausibility/belief measures, possibility/necessity measures, and probability measures, which are a subset of classical measures.
Definitions
Let be a universe of discourse, be a class of subsets of , and . A function where
is called a fuzzy measure.
A fuzzy measure is called normalized or regular if .
Properties of fuzzy measures
A fuzzy measure is:
additive if for any such that , we have ;
supermodular if for any , we have ;
submodular if for any , we have ;
superadditive if for any such that , we have ;
subadditive if for any such that , we have ;
symmetric if for any , we have implies ;
Boolean if for any , we have or .
Understanding the properties of fuzzy measures is useful in application. When a fuzzy measure is used to define a function such as the Sugeno integral or Choquet integral, these properties will be crucial in understanding the function's behavior. For instance, the Choquet integral with respect to an additive fuzzy measure reduces to the Lebesgue integral. In discrete cases, a symmetric fuzzy measur
|
https://en.wikipedia.org/wiki/Edward%20O.%20Thorp
|
Edward Oakley Thorp (born August 14, 1932) is an American mathematics professor, author, hedge fund manager, and blackjack researcher. He pioneered the modern applications of probability theory, including the harnessing of very small correlations for reliable financial gain.
Thorp is the author of Beat the Dealer, which mathematically proved that the house advantage in blackjack could be overcome by card counting. He also developed and applied effective hedge fund techniques in the financial markets, and collaborated with Claude Shannon in creating the first wearable computer.
Thorp received his Ph.D. in mathematics from the University of California, Los Angeles in 1958, and worked at the Massachusetts Institute of Technology (MIT) from 1959 to 1961. He was a professor of mathematics from 1961 to 1965 at New Mexico State University, and then joined the University of California, Irvine where he was a professor of mathematics from 1965 to 1977 and a professor of mathematics and finance from 1977 to 1982.
Background
Thorp was born in Chicago, but moved to southern California in his childhood. He had an early aptitude for science, and often tinkered with experiments of his own creation. He was one of the youngest amateur radio operators when he was certified at age 12. Thorp went on to win scholarships by doing well in chemistry and physics competitions (one instance led him to meeting President Truman), ultimately electing to go to UC Berkeley for his undergraduate degree.
|
https://en.wikipedia.org/wiki/Commit%20%28data%20management%29
|
In computer science and data management, a commit is the making of a set of tentative changes permanent, marking the end of a transaction and providing Durability to ACID transactions. A commit is an act of committing. The record of commits is called the commit log.
In terms of transactions, the opposite of commit is to discard the tentative changes of a transaction, a rollback.
The transaction, commit and rollback concepts are key to the ACID property of databases.
A COMMIT statement in SQL ends a transaction within a relational database management system (RDBMS) and makes all changes visible to other users. The general format is to issue a BEGIN WORK (or BEGIN TRANSACTION, depending on the database vendor) statement, one or more SQL statements, and then the COMMIT statement. Alternatively, a ROLLBACK statement can be issued, which undoes all the work performed since BEGIN WORK was issued. A COMMIT statement will also release any existing savepoints that may be in use.
References
See also
Atomic commit
Two-phase commit protocol
Three-phase commit protocol
Data management
SQL
Transaction processing
|
https://en.wikipedia.org/wiki/Institute%20of%20Mathematics%2C%20Physics%2C%20and%20Mechanics
|
Institute of Mathematics, Physics, and Mechanics (; IMFM) is the leading research institution in the areas of mathematics and theoretical computer science in Slovenia. It includes researchers from University of Ljubljana, University of Maribor and University of Primorska. It was founded in 1960.
The IMFM is composed of the following departments:
Department of Mathematrics
Department of Physics
Department of Theoretical Computer Science
The director is Jernej Kozak.
References
External links
Research institutes in Slovenia
Mathematical institutes
Physics research institutes
Scientific organizations established in 1960
Scientific organizations in Ljubljana
|
https://en.wikipedia.org/wiki/Gilles%20Brassard
|
Gilles Brassard, is a faculty member of the Université de Montréal, where he has been a Full Professor since 1988 and Canada Research Chair since 2001.
Education and early life
Brassard received a Ph.D. in Computer Science from Cornell University in 1979, working in the field of cryptography with John Hopcroft as his advisor.
Research
Brassard is best known for his fundamental work in quantum cryptography, quantum teleportation, quantum entanglement distillation, quantum pseudo-telepathy, and the classical simulation of quantum entanglement. Some of these concepts have been implemented in the laboratory.
In 1984, together with Charles H. Bennett, he invented the BB84 protocol for quantum cryptography. He later extended this work to include the Cascade error correction protocol, which performs efficient detection and correction of noise caused by eavesdropping on quantum cryptographic signals.
Awards and honours
Brassard was the editor-in-chief of the Journal of Cryptology from 1991 to 1998. In 2000, he won the Prix Marie-Victorin, the highest scientific award of the government of Quebec. He was elected as a Fellow of the International Association for Cryptologic Research in 2006, the first Canadian to be so honored. In June 2010, he was awarded the Gerhard Herzberg Canada Gold Medal, Canada's highest scientific honour. Brassard was elected a Fellow of the Royal Society of Canada and the Royal Society of London (2013). His nomination reads: On December 30, 2013, the Gove
|
https://en.wikipedia.org/wiki/STW%20%28disambiguation%29
|
STW or StW may refer to:
Business
Scott Tallon Walker Architects
Stop the War Coalition, an anti-war group in the United Kingdom
Mathematics
The Shimura-Taniyama-Weil conjecture, a generalization of Fermat's Last Theorem.
Music
Salt the Wound, a deathcore band
Silence the World, third album by the Swedish band Adept
Television
KSTW, a television station
Secrets of a Teenage Witch, a 3D animated series
STW-9, a television station in Perth, Australia
Scott the Woz, a web comedy review series
Utility companies
Severn Trent Water
Sewage treatment, Sewage Treatment Works
Transport
MTR station code for Sha Tin Wai station, Hong Kong
National Rail station code for Strawberry Hill railway station, London, England
Other
Fortnite: Save the World, a survival game
Search The Web, a milder version of computer jargon acronym STFW
Shogun: Total War, a PC strategy game.
Speed through water, nautical term
Sport Touring Wagon, an alternative marketing name for Crossover (automobile) style vehicles.
IATA code for Stavropol Shpakovskoye Airport
Super Tourenwagen Cup, the German Supertouring car championship (until 1999)
Surviving the World, a daily webcomic.
"Stop the world", a global pause in a computer program for garbage collection.
ScrewTurn Wiki, software
|
https://en.wikipedia.org/wiki/Newman%20projection
|
A Newman projection is a drawing that helps visualize the 3-dimensional structure of a molecule. This projection most commonly sights down a carbon-carbon bond, making it a very useful way to visualize the stereochemistry of alkanes. A Newman projection visualizes the conformation of a chemical bond from front to back, with the front atom represented by the intersection of three lines (a dot) and the back atom as a circle. The front atom is called proximal, while the back atom is called distal. This type of representation clearly illustrates the specific dihedral angle between the proximal and distal atoms.
This projection is named after American chemist Melvin Spencer Newman, who introduced it in 1952 as a partial replacement for Fischer projections, which are unable to represent conformations and thus conformers properly. This diagram style is an alternative to a sawhorse projection, which views a carbon-carbon bond from an oblique angle, or a wedge-and-dash style, such as a Natta projection. These other styles can indicate the bonding and stereochemistry, but not as much conformational detail.
A Newman projection can also be used to study cyclic molecules, such as the chair conformation of cyclohexane:
Because of the free rotation around single bonds, there are various conformations for a single molecule. Up to six unique conformations may be drawn for any given chemical bond. Each conformation is drawn by rotation of either the proximal or distal atom 60 degrees. Of t
|
https://en.wikipedia.org/wiki/Eclipsed%20conformation
|
In chemistry an eclipsed conformation is a conformation in which two substituents X and Y on adjacent atoms A, B are in closest proximity, implying that the torsion angle X–A–B–Y is 0°. Such a conformation can exist in any open chain, single chemical bond connecting two sp3-hybridised atoms, and it is normally a conformational energy maximum. This maximum is often explained by steric hindrance, but its origins sometimes actually lie in hyperconjugation (as when the eclipsing interaction is of two hydrogen atoms).
In order to gain a deeper understanding of eclipsed conformations in organic chemistry, it is first important to understand how organic molecules are arranged around bonds, as well as how they move and rotate.
In the example of ethane, two methyl groups are connected with a carbon-carbon sigma bond, just as one might connect two Lego pieces through a single “stud” and “tube”. With this image in mind, if the methyl groups are rotated around the bond, they will remain connected; however, the shape will change. This leads to multiple possible three-dimensional arrangements, known as conformations, conformational isomers (conformers), or sometimes rotational isomers (rotamers).
Organic chemistry
Conformations can be described by dihedral angles, which are used to determine the placements of atoms and their distance from one another and can be visualized by Newman projections. A dihedral angle can indicate staggered and eclipsed orientation, but is specifically used
|
https://en.wikipedia.org/wiki/David%20Adriaan%20van%20Dorp
|
David 'Davy' Adriaan van Dorp (April 27, 1915 in Amsterdam – February 19, 1995 in Vlaardingen) was a Dutch chemist.
Biography
Van Dorp was born as the son of Hendrik van Dorp and Maria van Dorp, and studied chemistry in Amsterdam where he received a PhD for his thesis Aneurine en gistphosphatase in 1941.
In 1946, while employed by the Dutch company Organon in Oss, Van Dorp and Jozef Ferdinand Arens ('Coco') (1914-2001) published the synthesis for vitamin A acid in the scientific journal Nature. In 1947, they completed the first full synthesis for the complex compound vitamin A, by taking the final step and turning the acid in an alcohol. Their synthesis was not to be used for commercial production, as an alternative route that was published soon after by Otto Isler (1910-1992) and co-workers at (Hoffmann-La Roche) turned out to be much more suited for upscaling.
Van Dorp joined the Unilever Research Laboratory in Vlaardingen in 1959, and was a key person in the studies regarding the role of arachidonic acid in the metabolic pathway to prostaglandin E2, in close cooperation with Sune K. Bergström who would later receive a Nobel prize for his work on prostaglandins.
In 1973 he became member of the Royal Netherlands Academy of Arts and Sciences.
References
O. Isler, W. Huber, A. Ronco, M. Kofler, Helv. Chim. Acta 30, 1911-1927 (1947)
D.A. van Dorp, R.K. Beerthuis, D.H. Nugteren, H. Vonkeman, Biochim. Biophys. Acta 90, 204-207 (1964)
S. Bergström, H. Danielsson, B. Samuels
|
https://en.wikipedia.org/wiki/Johann%20Heinrich%20Diemer
|
Johann Heinrich (Harry) Diemer (7 November 1904 – June 1945) was born in Dronrijp, the Netherlands. His father was the reverend N. Diemer, who served at the Reformed Church at Vijfhuizen. He studied biology at the University of Leiden. He studied the ideas of Abraham Kuyper, Herman Bavinck and Jan Woltjer, and soon became an adherent of Herman Dooyeweerd and D. H. Th. Vollenhoven's Reformational philosophy.
He gave much of his free time to the Association for Calvinistic Philosophy; he was secretary to the editorial board for its journal Philosophia Reformata from its inception in 1936. During the Second World War, he became acquainted with the young biology student Jan Lever, the later professor of zoology at the Vrije Universiteit Amsterdam. After the War, Lever spoke highly of Diemer as a biologist and theoretician, and he dedicated his book, Creatie en Evolutie (1956), to Diemer.
In January 1945 Diemer was arrested by the Nazis and was sent to the Neuengamme concentration camp. He died in 1945, shortly after having been liberated by the British.
References
Herman Dooyeweerd. 'In memory of Johann "Harry" Heinrich Diemer', in Nature and Miracle (originally published in Dutch in Philosophia Reformata).
Chris Gousmett. "A latter day Augustinian: Diemer, creation and miracle".
H. Cook and A.C. Flipse, "Jan Lever: Challenging the Role of Typological Thinking in Reformational Views of Biology", in: Philosophia Reformata 82/1 (2017), 3-25
Books
Nature and Miracle (Wedge: T
|
https://en.wikipedia.org/wiki/Attenuation%20length
|
In physics, the attenuation length or absorption length is the distance into a material when the probability has dropped to that a particle has not been absorbed. Alternatively, if there is a beam of particles incident on the material, the attenuation length is the distance where the intensity of the beam has dropped to , or about 63% of the particles have been stopped.
Mathematically, the probability of finding a particle at depth into the material is calculated by the Beer–Lambert law:
.
In general is material- and energy-dependent.
See also
Beer's Law
Mean free path
Attenuation coefficient
Attenuation (electromagnetic radiation)
Radiation length
References
https://web.archive.org/web/20050215215652/http://www.ct.infn.it/~rivel/Glossario/node2.html
External links
http://henke.lbl.gov/optical_constants/atten2.html
Particle physics
Experimental particle physics
|
https://en.wikipedia.org/wiki/Radiation%20length
|
In particle physics, the radiation length is a characteristic of a material, related to the energy loss of high energy particles electromagnetically interacting with it. It is defined as the mean length (in cm) into the material at which the energy of an electron is reduced by the factor 1/e.
Definition
In materials of high atomic number (e.g. tungsten, uranium, plutonium) the electrons of energies >~10 MeV predominantly lose energy by , and high-energy photons by pair production. The characteristic amount of matter traversed for these related interactions is called the radiation length , usually measured in g·cm−2. It is both the mean distance over which a high-energy electron loses all but of its energy by , and of the mean free path for pair production by a high-energy photon. It is also the appropriate length scale for describing high-energy electromagnetic cascades.
The radiation length for a given material consisting of a single type of nucleus can be approximated by the following expression:
where is the atomic number and is mass number of the nucleus.
For , a good approximation is
where
is the number density of the nucleus,
denotes the reduced Planck constant,
is the electron rest mass,
is the speed of light,
is the fine-structure constant.
For electrons at lower energies (below few tens of MeV), the energy loss by ionization is predominant.
While this definition may also be used for other electromagnetic interacting particles beyond leptons and
|
https://en.wikipedia.org/wiki/National%20Ocean%20Sciences%20Bowl
|
The National Ocean Sciences Bowl (NOSB) is a national high-school science competition managed by the Consortium for Ocean Leadership. It follows a quiz-bowl format, with lockout buzzers and extended team challenge questions to test students on their knowledge of oceanography. Questions cover the fields of biology, chemistry, geology, geography, social science, technology, and physics. The purpose of the event is to increase knowledge of the ocean among high school students and, ultimately, magnify public understanding of ocean research.
The annual competition was first held in 1998, the International Year of the Ocean. Twenty-five U.S. regions compete in the NOSB, each with its own regional competitions. The regional competitions are coordinated by Regional Coordinators, who are typically affiliated with a university in their region. Each year, approximately 2,000 students from 300 schools across the nation compete for prizes and a trip to the national competition. Students who participate are eligible to apply for the National Ocean Scholar Program.
The NOSB is a creation of oceanographer Rick Spinrad.
Format and scoring
Types of questions
Toss-up: These are multiple choice questions that can be answered by any of the 4 active players on either team in play. Teams have 5 seconds to buzz in and answer the question. If the first team's answer is incorrect, the opposing team will get another 5 seconds to answer. The team that buzzes in first gets to answer the question. A
|
https://en.wikipedia.org/wiki/Alex%20Elmsley
|
Alex Elmsley (2 March 1929 – 8 January 2006) was a Scottish magician and computer programmer. He was notable for his invention of the Ghost Count or Elmsley Count, creating mathematical card tricks, and for publishing on the mathematics of playing card shuffling.
He began practising magic in 1946, as a teenager. He studied physics and mathematics at Cambridge University; whilst there he was also secretary of the Pentacle Club. He was a patent agent, and later a computer expert, in his day job. Otherwise, he was an amateur card and close-up magician. He was awarded an Academy of Magical Arts Creative Fellowship in 1972.
He created a number of well-known magic tricks, including The Four Card Trick, Between Your Palms, Point Of Departure and Diamond Cut Diamond.
In 1975 he briefly toured the US giving a highly praised lecture known as the "Dazzle Card Act", which consisted of a magic act followed by a detailed discussion of routining. Notes on the lecture were released under the title Cardwork. Elmsley was the subject of The Collected Works of Alex Elmsley (vol. 1 1991, vol. 2 1994).
He named the special count used in The Four Card Trick the ghost count, though it would later become known as the Elmsley Count.
References
Notes
External links
Elmsley on Magicdirectory.com
Elmsley from Magicweek.co.uk
British magicians
1929 births
2006 deaths
Academy of Magical Arts Creative Fellowship winners
Academy of Magical Arts Lifetime Achievement Fellowship winners
|
https://en.wikipedia.org/wiki/Prime%20power
|
In mathematics, a prime power is a positive integer which is a positive integer power of a single prime number.
For example: , and are prime powers, while
, and are not.
The sequence of prime powers begins:
2, 3, 4, 5, 7, 8, 9, 11, 13, 16, 17, 19, 23, 25, 27, 29, 31, 32, 37, 41, 43, 47, 49, 53, 59, 61, 64, 67, 71, 73, 79, 81, 83, 89, 97, 101, 103, 107, 109, 113, 121, 125, 127, 128, 131, 137, 139, 149, 151, 157, 163, 167, 169, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 243, 251, … .
The prime powers are those positive integers that are divisible by exactly one prime number; in particular, the number 1 is not a prime power. Prime powers are also called primary numbers, as in the primary decomposition.
Properties
Algebraic properties
Prime powers are powers of prime numbers. Every prime power (except powers of 2) has a primitive root; thus the multiplicative group of integers modulo pn (that is, the group of units of the ring Z/pnZ) is cyclic.
The number of elements of a finite field is always a prime power and conversely, every prime power occurs as the number of elements in some finite field (which is unique up to isomorphism).
Combinatorial properties
A property of prime powers used frequently in analytic number theory is that the set of prime powers which are not prime is a small set in the sense that the infinite sum of their reciprocals converges, although the primes are a large set.
Divisibility properties
The totient function (φ) and
|
https://en.wikipedia.org/wiki/Footedness
|
In human biology, footedness is the natural preference of one's left or right foot for various purposes. It is the foot equivalent of handedness. While purposes vary, such as applying the greatest force in a certain foot to complete the action of kick as opposed to stomping, footedness is most commonly associated with the preference of a particular foot in the leading position while engaging in foot- or kicking-related sports, such as association football and kickboxing. A person may thus be left-footed, right-footed or ambipedal (able to use both feet equally well).
Ball games
In association football, the ball is predominantly struck by the foot. Footedness may refer to the foot a player uses to kick with the greatest force and skill. Most people are right-footed, kicking with the right leg. Capable left-footed footballers are rare and therefore quite sought after. As rare are "two-footed" players, who are equally capable with both feet. Such players make up only one sixth of players in the top professional leagues in Europe. Two-footedness can be learnt, a notable case being England international Tom Finney, but can only be properly developed in the early years. In Australian Rules Football, several players are equally adept at using both feet to kick the ball, such as Sam Mitchell and Charles Bushnell (footballer, retired).
In basketball, a sport composed almost solely of right-handed players, it is common for most athletes to have a dominant left leg which they would
|
https://en.wikipedia.org/wiki/William%20McGinnis
|
William McGinnis, Ph.D. is a molecular biologist and professor of biology at the University of California San Diego. At UC San Diego he has also served as the Chairman of the Department of Biology from July 1998 - June 1999, as Associate Dean of the Division of Natural Sciences from July 1, 1999 - June 2000, and as Interim Dean of the newly established Division of Biological Sciences from July 1, 2000 - February 1, 2001. Dr. McGinnis was appointed Dean of the Divisional Biological Sciences on July 1, 2013.
He received his Ph.D. from UC Berkeley in 1982 and was a Jane Coffin Childs postdoctoral fellow at the University of Basel. From 1984 to 1995, he was on the faculty of Yale University. He received a Searle Scholar Award, a Presidential Young Investigator Award, and a Dreyfuss Teacher/Scholar Award. Dr. McGinnis was elected to the American Academy of Arts and Sciences in 2010, and the National Academy of Sciences in 2019.
Research
McGinnis studies the evolutionary changes in transcription factors by looking at the Hox genes. His main research has been in Drosophila, comparing Hox genes within that species with Hox genes in other species, to see they are conserved (kept intact) during evolution. He also studies how Hox transcription functions control morphogenesis, and how changes in the Hox proteins, cofactors, and DNA targets affect morphology. One long-term objective of the research in his lab is to understand the molecular interactions that underlie functional speci
|
https://en.wikipedia.org/wiki/Erwin%20Baur
|
Erwin Baur (16 April 1875, in Ichenheim, Grand Duchy of Baden – 2 December 1933) was a German geneticist and botanist. Baur worked primarily on plant genetics. He was director of the Kaiser Wilhelm Institute for Breeding Research (since 1938 Erwin Baur-Institute). Baur is considered to be the father of plant virology. He discovered the inheritance of plastids.
In 1908 Baur demonstrated a lethal gene in the Antirrhinum plant. In 1909 working on the chloroplast genes in Pelargonium (geraniums) he showed that they violated four of Mendel's five laws.
Baur stated that
plastids are carriers of hereditary factors which are able to mutate.
in variegated plants, random sorting out of plastids is taking place.
the genetic results indicate a biparental inheritance of plastids by egg cells and sperm cells in pelargonium.
Since the 1930s and the work of Otto Renner, plastid inheritance became a widely accepted genetic theory.
In 1921 and 1932, together with Fritz Lenz and Eugen Fischer, Baur coauthored two volumes that became the book Menschliche Erblichkeitslehre (Human Heredity), which was a major influence on the racial theories of Adolf Hitler. The work served a chief inspiration for biological support in Hitler's Mein Kampf.
References
External links
Short Biography, bibliography, and links on digitized sources in the Virtual Laboratory of the Max Planck Institute for the History of Science
1875 births
1933 deaths
People from Ortenaukreis
People from the Grand Duchy of Baden
|
https://en.wikipedia.org/wiki/Boris%20Ephrussi
|
Boris Ephrussi (; 9 May 1901 – 2 May 1979), Professor of Genetics at the University of Paris, was a Russo-French geneticist.
Boris was born on 9 May 1901 into a Jewish family. His father, Samuel Osipovich Ephrussi, was a chemical engineer; his grandfather, Joseph Ephrusi (Efrusi), was the founder of a banking dynasty in Kishinev. He published two papers in November 1966 which represented a key step in a decade of research in his laboratory. This research helped transform mammalian, and especially human, genetics.
Boris started his scientific training as a Russian émigré in 1920. He studied the initiation and regulation of embryological processes by intracellular and extracellular factors. A major strand of his early research concerned the effect of temperature on the development of fertilized sea urchin eggs. In this work he used a micromanipulator, which was developed by Robert Chambers, an American biologist.
During Ephrussi's time, writing a second dissertation was standard practice in France. Ephrussi's involved culturing tissues. Ephrussi ran into difficulties typically associated with early tissue culture techniques, but despite these obstacles Ephrussi managed to conclude from studies of brachyury in mice that intrinsic factors (i.e. genes) play a key role in development.
As the next phase of his career, Ephrussi coupled his embryological concerns with a firm conviction that one must understand the role of genes in order to decipher embryological processes. He move
|
https://en.wikipedia.org/wiki/Neil%20Campbell%20%28scientist%29
|
Neil Allison Campbell (April 17, 1946 – October 21, 2004) was an American scientist known best for his textbook, Biology, first published in 1987 and repeatedly through many subsequent editions. The title is popular worldwide and has been used by over 700,000 students in both high school and college-level classes.
Education
Campbell earned his M.S. in zoology from the University of California, Los Angeles and his Ph.D. in Plant Biology from the University of California, Riverside. He taught collegiate classes for over 30 years at Cornell University, Pomona College, University of California, Riverside, and San Bernardino Valley College.
Work
Campbell received multiple awards: the Distinguished Alumnus Award from University of California, Riverside in 2001 and the first ever Outstanding Professor Award from San Bernardino Valley College in 1986.
Campbell was also a researcher who studied desert and coastal plants. He conducted research on how certain plants would adjust in environments with different salinity, temperature, and pH. In addition, he conducted studies on the Mimosa plant and other legumes.
Death
Campbell died on 21 October 2004 of heart failure just after the manuscript for the seventh international edition of Biology was completed. The Neil Allison Campbell Endowed Research Award was created at UC Riverside to honor his memory.
References
External links
Official website of Campbell Biology
1946 births
2004 deaths
American textbook writers
American male non-
|
https://en.wikipedia.org/wiki/Matt%20Curtin
|
Matt Curtin (born 1973) is a computer scientist and entrepreneur in Columbus, Ohio best known for his work in cryptography and firewall systems. He is the founder of Interhack Corporation, first faculty advisor of Open Source Club at The Ohio State University, and lecturer in the Department of Computer Science and Engineering at The Ohio State University, where he teaches a Common Lisp course. The author of two books, Developing Trust: Online Privacy and Security and Brute Force: Cracking the Data Encryption Standard.
Curtin's work includes helping to prove the weakness of the Data Encryption Standard and providing expert testimony in Blumofe v. Pharmatrak, in which a key ruling was made by the U.S. Court of Appeals for the First Circuit, showing how the Electronic Communications Privacy Act (ECPA) applies to Web technology.
References
External links
Matt Curtin's homepage
Interhack Corporation
1973 births
Computer systems researchers
American computer scientists
Cypherpunks
Living people
Ohio State University faculty
Businesspeople from Columbus, Ohio
Place of birth missing (living people)
Engineers from Ohio
|
https://en.wikipedia.org/wiki/List%20of%20mathematical%20identities
|
This article lists mathematical identities, that is, identically true relations holding in mathematics.
Bézout's identity (despite its usual name, it is not, properly speaking, an identity)
Binomial inverse theorem
Binomial identity
Brahmagupta–Fibonacci two-square identity
Candido's identity
Cassini and Catalan identities
Degen's eight-square identity
Difference of two squares
Euler's four-square identity
Euler's identity
Fibonacci's identity see Brahmagupta–Fibonacci identity or Cassini and Catalan identities
Heine's identity
Hermite's identity
Lagrange's identity
Lagrange's trigonometric identities
MacWilliams identity
Matrix determinant lemma
Newton's identity
Parseval's identity
Pfister's sixteen-square identity
Sherman–Morrison formula
Sophie Germain identity
Sun's curious identity
Sylvester's determinant identity
Vandermonde's identity
Woodbury matrix identity
Identities for classes of functions
Exterior calculus identities
Fibonacci identities: Combinatorial Fibonacci identities and Other Fibonacci identities
Hypergeometric function identities
List of integrals of logarithmic functions
List of topics related to
List of trigonometric identities
Inverse trigonometric functions
Logarithmic identities
Summation identities
Vector calculus identities
See also
External links
A Collection of Algebraic Identities
Matrix Identities
Identities
|
https://en.wikipedia.org/wiki/Topological%20graph%20theory
|
In mathematics, topological graph theory is a branch of graph theory. It studies the embedding of graphs in surfaces, spatial embeddings of graphs, and graphs as topological spaces. It also studies immersions of graphs.
Embedding a graph in a surface means that we want to draw the graph on a surface, a sphere for example, without two edges intersecting. A basic embedding problem often presented as a mathematical puzzle is the three utilities problem. Other applications can be found in printing electronic circuits where the aim is to print (embed) a circuit (the graph) on a circuit board (the surface) without two connections crossing each other and resulting in a short circuit.
Graphs as topological spaces
To an undirected graph we may associate an abstract simplicial complex C with a single-element set per vertex and a two-element set per edge. The geometric realization |C| of the complex consists of a copy of the unit interval [0,1] per edge, with the endpoints of these intervals glued together at vertices. In this view, embeddings of graphs into a surface or as subdivisions of other graphs are both instances of topological embedding, homeomorphism of graphs is just the specialization of topological homeomorphism, the notion of a connected graph coincides with topological connectedness, and a connected graph is a tree if and only if its fundamental group is trivial.
Other simplicial complexes associated with graphs include the Whitney complex or clique complex, with a s
|
https://en.wikipedia.org/wiki/Centro%20de%20Investigaci%C3%B3n%20en%20Matem%C3%A1ticas
|
The Centro de Investigación en Matemáticas (lit. "Center for Research in Mathematics"), commonly known by its acronym in Spanish as CIMAT, is a North American scientific research institution based in the city of Guanajuato, in the homonym State of Guanajuato, in central Mexico, and was established in the year 1980. It belongs to the Mexican National System of Public Centers of Research under administration of the country's National Council of Science and Technology (CONACyT).
CIMAT is oriented to scientific research under the auspices of the Mexican government. It is also devoted to the generation, dissemination and application of knowledge in specialized fields, as well as to the formation of human resources in the areas of pure and applied mathematics, probability and statistics, and computer science. Of CIMAT's faculty, more than 80% of the researchers belong to the Mexican National System of Researchers (SNI). Academically, the center is organized in four main areas: pure mathematics, applied mathematics, probability and statistics, and computer science.
The research groups of the center interact strongly with similar institutions in Mexico and in foreign countries. This provides a continuous flow of visitors from around the world and provides conferences, workshops, and seminars.
The educational programs at CIMAT currently have more than 200 students, who come from all over the country and from abroad (mainly from Central and South American countries, but also from A
|
https://en.wikipedia.org/wiki/Equivalent%20weight
|
In chemistry, equivalent weight (also known as gram equivalent or equivalent mass) is the mass of one equivalent, that is the mass of a given substance which will combine with or displace a fixed quantity of another substance. The equivalent weight of an element is the mass which combines with or displaces 1.008 gram of hydrogen or 8.0 grams of oxygen or 35.5 grams of chlorine. These values correspond to the atomic weight divided by the usual valence; for oxygen as example that is 16.0 g / 2 = 8.0 g.
For acid–base reactions, the equivalent weight of an acid or base is the mass which supplies or reacts with one mole of hydrogen cations (). For redox reactions, the equivalent weight of each reactant supplies or reacts with one mole of electrons (e−) in a redox reaction.
Equivalent weight has the units of mass, unlike atomic weight, which is now used as a synonym for relative atomic mass and is dimensionless. Equivalent weights were originally determined by experiment, but (insofar as they are still used) are now derived from molar masses. The equivalent weight of a compound can also be calculated by dividing the molecular mass by the number of positive or negative electrical charges that result from the dissolution of the compound.
In history
The first equivalent weights were published for acids and bases by Carl Friedrich Wenzel in 1777. A larger set of tables was prepared, possibly independently, by Jeremias Benjamin Richter, starting in 1792. However, neither Wenzel no
|
https://en.wikipedia.org/wiki/Surface%20bundle
|
In mathematics, a surface bundle is a bundle in which the fiber is a surface. When the base space is a circle the total space is three-dimensional and is often called a surface bundle over the circle.
See also
Mapping torus
Geometric topology
|
https://en.wikipedia.org/wiki/Hydrobromide
|
In chemistry, a hydrobromide is an acid salt resulting, or regarded as resulting, from the reaction of hydrobromic acid with an organic base (e.g. an amine). The compounds are similar to hydrochlorides.
Some drugs are formulated as hydrobromides, e.g. eletriptan hydrobromide.
See also
Bromide, inorganic salts of hydrobromic acid
Bromine, the element Br
Free base (chemistry)
Acid salts
Salts
Organobromides
|
https://en.wikipedia.org/wiki/Oscar%20Sala
|
Oscar Sala (born March 26, 1922, in Milan, Italy, d. January 2, 2010 in São Paulo, Brazil), Italian-Brazilian nuclear physicist and important scientific leader, Emeritus Professor of the Institute of Physics, University of São Paulo.
Early life and education
Sala graduated in physics in 1943, at the then recently created University of São Paulo, in São Paulo, Brazil. The Department of Physics of the Faculty of Philosophy, Sciences and Letters was started with two imminent Italian physicists, Gleb Wataghin and Giuseppe Occhialini, who specialized in researching cosmic radiation. He was contemporary with a brilliant generation of young Brazilian physicians, such as César Lattes, José Leite Lopes, Mário Schenberg, Roberto Salmeron, Marcelo Damy de Souza Santos and Jayme Tiomno. While still a student, Oscar Sala started research work with the group. In 1945, Sala published with Wataghin an important paper on showers of penetrating nuclear particles.
Career in academia
Soon after graduation, he was hired as a teaching assistant by the Chair of General and Experimental Physics, led by Prof. Marcelo Damy de Souza Santos. His entire scientific and teaching career was spent at the same institution, which later became the Institute of Physics. In this new capacity, Sala became head of the Department of Nuclear Physics (1970–1979 and 1983–1987).
In 1946 Oscar Sala received a scholarship from the Rockefeller Foundation and went to study in the U.S., first at the University of Illinois
|
https://en.wikipedia.org/wiki/Online%20learning
|
Online learning may refer to study in home
Educational technology, or e-learning
E-learning (theory)
Distance education
Virtual school
Online learning in higher education
Massive open online courses
Online machine learning, in computer science and statistics
|
https://en.wikipedia.org/wiki/Jayme%20Tiomno
|
Jayme Tiomno (April 16, 1920 in Rio de Janeiro – January 12, 2011 in Rio de Janeiro) was a Brazilian experimental and theoretical physicist with interests in particle physics and general relativity. He was member of the Brazilian Academy of Sciences and a recipient of the Brazilian Order of Scientific Merit. He was the son of Jewish Russian immigrants.
He was a founder of the CBPF - Centro Brasileiro de Pesquisas Físicas (Brazilian Center of Physics Research) and one responsible for the creation of the Brazilian Physical Society.
Selected bibliography
References
External links
Jayme Tiomno Biography. Brazilian Academy of Sciences.
1920 births
2011 deaths
Brazilian physicists
Brazilian nuclear physicists
Members of the Brazilian Academy of Sciences
Recipients of the Great Cross of the National Order of Scientific Merit (Brazil)
Brazilian Jews
Brazilian people of Russian-Jewish descent
University of São Paulo alumni
21st-century Brazilian scientists
20th-century Brazilian scientists
|
https://en.wikipedia.org/wiki/M%C3%A1rio%20Schenberg
|
Mário Schenberg (var. Mário Schönberg, Mario Schonberg, Mário Schoenberg; July 2, 1914 – November 10, 1990) was a Brazilian electrical engineer, physicist, art critic and writer.
Early life
Schenberg was born in Recife, Brazil. His parents were Russian-Jews of German origin. From early on he showed remarkable ability for mathematics, enchanting himself with geometry, which had a strong influence on his works. Schenberg took the primary and secondary courses in Recife. Because of his family's financial limitations, he was not able to study in Europe. He then entered the Faculty of Engineering of Recife in 1931.
Scientific work
The Urca process
Widely regarded as one of Brazil's most important theoretical physicists, Schenberg is best remembered for his contributions to astrophysics, particularly the theory of nuclear processes in the formation of supernova stars. He provided the inspiration for the name of the so-called Urca process, a cycle of nuclear reactions in which a nucleus loses energy by absorbing an electron and then re-emitting a beta particle plus a neutrino-antineutrino pair, leading to the loss of internal supporting pressure and consequent collapse and explosion in the form of a supernova. George Gamow (1904–1968) was inspired to name the process Urca after the name of a casino in Rio de Janeiro, when Schenberg remarked to him that "the energy disappears in the nucleus of the supernova as quickly as the money disappeared at that roulette table".
Schönberg–
|
https://en.wikipedia.org/wiki/Gleb%20Wataghin
|
Gleb Vassielievich Wataghin (November 3, 1899 in Birzula, Russian Empire – October 10, 1986 in Turin, Italy) was a Ukrainian-Italian theoretical and experimental physicist and a great scientific leader who gave a great impulse to the teaching and research on physics in two continents: in the University of São Paulo, São Paulo, Brazil; and in the University of Turin, Turin, Italy.
Wataghin was hired in 1934 to found with other European physicists the Department of Physics of the recently founded University of São Paulo. There, he was the tutor of a group of young physicists, such as César Lattes, Oscar Sala, Mário Schenberg, Roberto Salmeron, Marcelo Damy de Souza Santos and Jayme Tiomno. The Institute of Physics of the State University of Campinas, in Campinas, Brazil, was named in his honour, as well as a prize in Physics. In 1955, he received an honorary doctorate from the University of São Paulo.
He was awarded the Feltrinelli Prize in 1951 and was national member of the Accademia Nazionale dei Lincei, from 1960.
Selected bibliography
Notes
External links
Predazzi, Ernesto: Gleb Wataghin. Brazilian Physical Society (in Portuguese)
Salmeron, Roberto A. Gleb Wataghin. Revista Estudos Avançados. Vol. 16, Jan./Apr. 2002. (In Portuguese)
1899 births
1986 deaths
20th-century Italian physicists
Expatriate academics in Brazil
People associated with the State University of Campinas
People from Odesa Oblast
Russian emigrants to Italy
Academic staff of the University of São
|
https://en.wikipedia.org/wiki/Hurwitz%20matrix
|
In mathematics, a Hurwitz matrix, or Routh–Hurwitz matrix, in engineering stability matrix, is a structured real square matrix constructed with coefficients of a real polynomial.
Hurwitz matrix and the Hurwitz stability criterion
Namely, given a real polynomial
the square matrix
is called Hurwitz matrix corresponding to the polynomial . It was established by Adolf Hurwitz in 1895 that a real polynomial with is stable
(that is, all its roots have strictly negative real part) if and only if all the leading principal minors of the matrix are positive:
and so on. The minors are called the Hurwitz determinants. Similarly, if then the polynomial is stable if and only if the principal minors have alternating signs starting with a negative one.
Hurwitz stable matrices
In engineering and stability theory, a square matrix is called a Hurwitz matrix if every eigenvalue of has strictly negative real part, that is,
for each eigenvalue . is also called a stable matrix, because then the differential equation
is asymptotically stable, that is, as
If is a (matrix-valued) transfer function, then is called Hurwitz if the poles of all elements of have negative real part. Note that it is not necessary that for a specific argument be a Hurwitz matrix — it need not even be square. The connection is that if is a Hurwitz matrix, then the dynamical system
has a Hurwitz transfer function.
Any hyperbolic fixed point (or equilibrium point) of a continuous dynamical system i
|
https://en.wikipedia.org/wiki/Flow%20net
|
A flow net is a graphical representation of two-dimensional steady-state groundwater flow through aquifers.
Construction of a flow net is often used for solving groundwater flow problems where the geometry makes analytical solutions impractical. The method is often used in civil engineering, hydrogeology or soil mechanics as a first check for problems of flow under hydraulic structures like dams or sheet pile walls. As such, a grid obtained by drawing a series of equipotential lines is called a flow net. The flow net is an important tool in analysing two-dimensional irrotational flow problems. Flow net technique is a graphical representation method.
Basic method
The method consists of filling the flow area with stream and equipotential lines, which are everywhere perpendicular to each other, making a curvilinear grid. Typically there are two surfaces (boundaries) which are at constant values of potential or hydraulic head (upstream and downstream ends), and the other surfaces are no-flow boundaries (i.e., impermeable; for example the bottom of the dam and the top of an impermeable bedrock layer), which define the sides of the outermost streamtubes (see figure 1 for a stereotypical flow net example).
Mathematically, the process of constructing a flow net consists of contouring the two harmonic or analytic functions of potential and stream function. These functions both satisfy the Laplace equation and the contour lines represent lines of constant head (equipotentials) and
|
https://en.wikipedia.org/wiki/Cofinal%20%28mathematics%29
|
In mathematics, a subset of a preordered set is said to be cofinal or frequent in if for every it is possible to find an element in that is "larger than " (explicitly, "larger than " means ).
Cofinal subsets are very important in the theory of directed sets and nets, where “cofinal subnet” is the appropriate generalization of "subsequence". They are also important in order theory, including the theory of cardinal numbers, where the minimum possible cardinality of a cofinal subset of is referred to as the cofinality of
Definitions
Let be a homogeneous binary relation on a set
A subset is said to be or with respect to if it satisfies the following condition:
For every there exists some that
A subset that is not frequent is called .
This definition is most commonly applied when is a directed set, which is a preordered set with additional properties.
Final functions
A map between two directed sets is said to be if the image of is a cofinal subset of
Coinitial subsets
A subset is said to be (or in the sense of forcing) if it satisfies the following condition:
For every there exists some such that
This is the order-theoretic dual to the notion of cofinal subset.
Cofinal (respectively coinitial) subsets are precisely the dense sets with respect to the right (respectively left) order topology.
Properties
The cofinal relation over partially ordered sets ("posets") is reflexive: every poset is cofinal in itself. It is also transitive:
|
https://en.wikipedia.org/wiki/Hensel%27s%20lemma
|
In mathematics, Hensel's lemma, also known as Hensel's lifting lemma, named after Kurt Hensel, is a result in modular arithmetic, stating that if a univariate polynomial has a simple root modulo a prime number , then this root can be lifted to a unique root modulo any higher power of . More generally, if a polynomial factors modulo into two coprime polynomials, this factorization can be lifted to a factorization modulo any higher power of (the case of roots corresponds to the case of degree for one of the factors).
By passing to the "limit" (in fact this is an inverse limit) when the power of tends to infinity, it follows that a root or a factorization modulo can be lifted to a root or a factorization over the -adic integers.
These results have been widely generalized, under the same name, to the case of polynomials over an arbitrary commutative ring, where is replaced by an ideal, and "coprime polynomials" means "polynomials that generate an ideal containing ".
Hensel's lemma is fundamental in -adic analysis, a branch of analytic number theory.
The proof of Hensel's lemma is constructive, and leads to an efficient algorithm for Hensel lifting, which is fundamental for factoring polynomials, and gives the most efficient known algorithm for exact linear algebra over the rational numbers.
Modular reduction and lifting
Hensel's original lemma concerns the relation between polynomial factorization over the integers and over the integers modulo a prime number and its
|
https://en.wikipedia.org/wiki/Richard%20P.%20Stanley
|
Richard Peter Stanley (born June 23, 1944) is an Emeritus Professor of Mathematics at the Massachusetts Institute of Technology, in Cambridge, Massachusetts. From 2000 to 2010, he was the Norman Levinson Professor of Applied Mathematics. He received his Ph.D. at Harvard University in 1971 under the supervision of Gian-Carlo Rota. He is an expert in the field of combinatorics and its applications to other mathematical disciplines.
Contributions
Stanley is known for his two-volume book Enumerative Combinatorics (1986–1999). He is also the author of Combinatorics and Commutative Algebra (1983) and well over 200 research articles in mathematics. He has served as thesis advisor to 60 doctoral students, many of whom have had distinguished careers in combinatorial research. Donald Knuth named Stanley as one of his combinatorial heroes in a 2023 interview.
Awards and honors
Stanley's distinctions include membership in the National Academy of Sciences (elected in 1995), the 2001 Leroy P. Steele Prize for Mathematical Exposition, the 2003 Schock Prize, a plenary lecture at the International Congress of Mathematicians (in Madrid, Spain), and election in 2012 as a fellow of the American Mathematical Society. In 2022 he was awarded the Leroy P. Steele Prize for Lifetime Achievement.
Selected publications
Stanley, Richard P. (1996). Combinatorics and Commutative Algebra, 2nd ed. .
Stanley, Richard P. (1997, 1999). Enumerative Combinatorics, Volumes 1 and 2. Cambridge Univers
|
https://en.wikipedia.org/wiki/George%20Devol
|
George Charles Devol Jr. (February 20, 1912 – August 11, 2011) was an American inventor, best known for creating Unimate, the first industrial robot. Devol's invention earned him the title "Grandfather of Robotics". The National Inventors Hall of Fame says, "Devol's patent for the first digitally operated programmable robotic arm represents the foundation of the modern robotics industry."
The concept of the robot arm has evolved over time with contributions from various individuals and researchers. However, the first patent for an industrial robot was filed in 1954 by George Devol, an American inventor and entrepreneur, who is often credited as the "father of the robot arm."
Early life
George Devol was born in an upper-middle-class family in Louisville, Kentucky. He attended Riordan Prep school.
United Cinephone
Foregoing higher education, Devol went into business in 1932, forming United Cinephone to produce variable area recording directly onto film for the new sound motion pictures ("talkies"). However, he later learned that companies like RCA and Western Electric were working in the same area, and discontinued the product.
During that time, Devol developed and patented industrial lighting and invented the automatic opening door.
World War II
In 1939, Devol applied for a patent for proximity controls for use in laundry press machines, based on a radio frequency field. This control would automatically open and close laundry presses when workers approached the machin
|
https://en.wikipedia.org/wiki/Total%20angular%20momentum%20quantum%20number
|
In quantum mechanics, the total angular momentum quantum number parametrises the total angular momentum of a given particle, by combining its orbital angular momentum and its intrinsic angular momentum (i.e., its spin).
If s is the particle's spin angular momentum and ℓ its orbital angular momentum vector, the total angular momentum j is
The associated quantum number is the main total angular momentum quantum number j. It can take the following range of values, jumping only in integer steps:
where ℓ is the azimuthal quantum number (parameterizing the orbital angular momentum) and s is the spin quantum number (parameterizing the spin).
The relation between the total angular momentum vector j and the total angular momentum quantum number j is given by the usual relation (see angular momentum quantum number)
The vector's z-projection is given by
where mj is the secondary total angular momentum quantum number, and the is the reduced Planck's constant. It ranges from −j to +j in steps of one. This generates 2j + 1 different values of mj.
The total angular momentum corresponds to the Casimir invariant of the Lie algebra so(3) of the three-dimensional rotation group.
See also
Principal quantum number
Orbital angular momentum quantum number
Magnetic quantum number
Spin quantum number
Angular momentum coupling
Clebsch–Gordan coefficients
Angular momentum diagrams (quantum mechanics)
Rotational spectroscopy
References
Albert Messiah, (1966). Quantum Mechanics (Vols
|
https://en.wikipedia.org/wiki/C%20parity
|
In physics, the C parity or charge parity is a multiplicative quantum number of some particles that describes their behavior under the symmetry operation of charge conjugation.
Charge conjugation changes the sign of all quantum charges (that is, additive quantum numbers), including the electrical charge, baryon number and lepton number, and the flavor charges strangeness, charm, bottomness, topness and Isospin (I3). In contrast, it doesn't affect the mass, linear momentum or spin of a particle.
Formalism
Consider an operation that transforms a particle into its antiparticle,
Both states must be normalizable, so that
which implies that is unitary,
By acting on the particle twice with the operator,
we see that and . Putting this all together, we see that
meaning that the charge conjugation operator is Hermitian and therefore a physically observable quantity.
Eigenvalues
For the eigenstates of charge conjugation,
.
As with parity transformations, applying twice must leave the particle's state unchanged,
allowing only eigenvalues of the so-called C-parity or charge parity of the particle.
Eigenstates
The above implies that for eigenstates, . Since antiparticles and particles have charges of opposite sign, only states with all quantum charges equal to zero, such as the photon and particle–antiparticle bound states like the neutral pion, η or positronium, are eigenstates of .
Multiparticle systems
For a system of free particles, the C parity is the product of C
|
https://en.wikipedia.org/wiki/Rough%20set
|
In computer science, a rough set, first described by Polish computer scientist Zdzisław I. Pawlak, is a formal approximation of a crisp set (i.e., conventional set) in terms of a pair of sets which give the lower and the upper approximation of the original set. In the standard version of rough set theory (Pawlak 1991), the lower- and upper-approximation sets are crisp sets, but in other variations, the approximating sets may be fuzzy sets.
Definitions
The following section contains an overview of the basic framework of rough set theory, as originally proposed by Zdzisław I. Pawlak, along with some of the key definitions. More formal properties and boundaries of rough sets can be found in Pawlak (1991) and cited references. The initial and basic theory of rough sets is sometimes referred to as "Pawlak Rough Sets" or "classical rough sets", as a means to distinguish from more recent extensions and generalizations.
Information system framework
Let be an information system (attribute–value system), where is a non-empty, finite set of objects (the universe) and is a non-empty, finite set of attributes such that for every . is the set of values that attribute may take. The information table assigns a value from to each attribute and object in the universe .
With any there is an associated equivalence relation :
The relation is called a -indiscernibility relation. The partition of is a family of all equivalence classes of and is denoted by (or ).
If , then and
|
https://en.wikipedia.org/wiki/Grothendieck%20group
|
In mathematics, the Grothendieck group, or group of differences, of a commutative monoid is a certain abelian group. This abelian group is constructed from in the most universal way, in the sense that any abelian group containing a homomorphic image of will also contain a homomorphic image of the Grothendieck group of . The Grothendieck group construction takes its name from a specific case in category theory, introduced by Alexander Grothendieck in his proof of the Grothendieck–Riemann–Roch theorem, which resulted in the development of K-theory. This specific case is the monoid of isomorphism classes of objects of an abelian category, with the direct sum as its operation.
Grothendieck group of a commutative monoid
Motivation
Given a commutative monoid , "the most general" abelian group that arises from is to be constructed by introducing inverse elements to all elements of . Such an abelian group always exists; it is called the Grothendieck group of . It is characterized by a certain universal property and can also be concretely constructed from .
If does not have the cancellation property (that is, there exists and in such that and ), then the Grothendieck group cannot contain . In particular, in the case of a monoid operation denoted multiplicatively that has a zero element satisfying for every the Grothendieck group must be the trivial group (group with only one element), since one must have
for every .
Universal property
Let M be a commutative monoid.
|
https://en.wikipedia.org/wiki/Multilocus%20sequence%20typing
|
Multilocus sequence typing (MLST) is a technique in molecular biology for the typing of multiple loci, using DNA sequences of internal fragments of multiple housekeeping genes to characterize isolates of microbial species.
The first MLST scheme to be developed was for Neisseria meningitidis, the causative agent of meningococcal meningitis and septicaemia. Since its introduction for the research of evolutionary history, MLST has been used not only for human pathogens but also for plant pathogens.
Principle
MLST directly measures the DNA sequence variations in a set of housekeeping genes and characterizes strains by their unique allelic profiles. The principle of MLST is simple: the technique involves PCR amplification followed by DNA sequencing. Nucleotide differences between strains can be checked at a variable number of genes depending on the degree of discrimination desired.
The workflow of MLST involves: 1) data collection, 2) data analysis and 3) multilocus sequence analysis. In the data collection step, definitive identification of variation is obtained by nucleotide sequence determination of gene fragments. In the data analysis step, all unique sequences are assigned allele numbers and combined into an allelic profile and assigned a sequence type (ST). If new alleles and STs are found, they are stored in the database after verification. In the final analysis step of MLST, the relatedness of isolates are made by comparing allelic profiles. Researchers do epidemiologic
|
https://en.wikipedia.org/wiki/Headroom%20%28audio%20signal%20processing%29
|
In digital and analog audio, headroom refers to the amount by which the signal-handling capabilities of an audio system can exceed a designated nominal level. Headroom can be thought of as a safety zone allowing transient audio peaks to exceed the nominal level without damaging the system or the audio signal, e.g., via clipping. Standards bodies differ in their recommendations for nominal level and headroom.
Digital audio
In digital audio, headroom is defined as the amount by which digital full scale (FS) exceeds the nominal level in decibels (dB). The European Broadcasting Union (EBU) specifies several nominal levels and resulting headroom for different applications.
Analog audio
In analog audio, headroom can mean low-level signal capabilities as well as the amount of extra power reserve available within the amplifiers that drive the loudspeakers.
Alignment level
Alignment level is an anchor point 9 dB below the nominal level, a reference level that exists throughout the system or broadcast chain, though it may imply different voltage levels at different points in the analog chain. Typically, nominal (not alignment) level is 0 dB, corresponding to an analog sine wave of voltage of 1.23 volts RMS (+4 dBu or 3.47 volts peak to peak). In the digital realm, alignment level is −18 dBFS.
AL = analog level
SPL = sound pressure level
See also
A-weighting
Audio system measurements
Equal-loudness contour
ITU-R 468 noise weighting
Loudness war
Noise measurement
Prog
|
https://en.wikipedia.org/wiki/Roberto%20Salmeron
|
Roberto Aureliano Salmeron (June 16, 1922 – June 17, 2020) was a Brazilian electrical engineer and experimental nuclear physicist and an emeritus Research Director at the French National Centre for Scientific Research (CNRS).
Salmeron was born in São Paulo. He did his undergraduate studies in electrical engineering at the Escola Politécnica da Universidade de São Paulo, in São Paulo, and in physics in the Federal University of Rio de Janeiro (then named Universidade do Brasil), in Rio de Janeiro. From 1947 to 1950, he worked as researcher and physics instructor at the Escola Politécnica and in the Department of Physics of the Faculty of Philosophy, Sciences and Letters of the University of São Paulo, where he studied cosmic radiation under Italian physicists Gleb Wataghin and Giuseppe Occhialini. From 1950 to 1953, Salmeron worked at the recently created Centro Brasileiro de Pesquisas Físicas (Brazilian Center of Physical Research) in Rio. In São Paulo and Rio, Salmeron was contemporary of a brilliant generation of young Brazilian physicists, such as César Lattes, José Leite Lopes, Oscar Sala, Mário Schenberg, Marcelo Damy de Souza Santos and Jayme Tiomno.
From 1953 onwards, Salmeron lived in Europe, first doing his Ph.D. from 1953 to 1955 at the University of Manchester, under Patrick Blackett, Nobel Prize winner of Physics, and then as an associate researcher in the European Organization for Nuclear Research (CERN), in Geneva, Switzerland, from 1955 to 1963.
In 1963, Sal
|
https://en.wikipedia.org/wiki/Marcelo%20Damy
|
Marcelo Damy de Sousa Santos (July 14, 1914 – November 29, 2009) was a Brazilian physicist.
Considered as one of the most important educators and researchers in physics in Brazil, along with Cesar Lattes, José Leite Lopes and Mario Schenberg, Damy was born in Campinas, São Paulo, in 1914, the son of Harald Egydio de Souza Santos a photographer, and Maria Luiza Damy de Souza Santos. He did his secondary studies in the State Gymnasium (later to be called Colégio Culto à Ciência) and was a keen student of sciences, particularly physics and chemistry.
In 1932, he was admitted to the Polytechnic School of the University of São Paulo to study electrical engineering, but eventually switched to physics at the invitation of Prof. Gleb Wataghin, a Russian physicist who was teaching at the time in the university, whose classes Damy enjoyed to listen, although they were given in a different course from his. He graduated in the first class of the course of physics at USP.
During his undergraduate years, Damy became interested in radioactivity. This interest started his successful lifelong career in experimental nuclear physics. After graduation, he went to Cambridge University, at 24, with a grant from the British Council, under the supervision of Prof. William L. Bragg (Nobel Prize in Physics). In England he became friends with Edmundo Barbosa da Silva, Oxford University student and future colleague in the Atomic Energy Commission of the Brazilian National Research Council. Back in Br
|
https://en.wikipedia.org/wiki/Quadratic%20assignment%20problem
|
The quadratic assignment problem (QAP) is one of the fundamental combinatorial optimization problems in the branch of optimization or operations research in mathematics, from the category of the facilities location problems first introduced by Koopmans and Beckmann.
The problem models the following real-life problem:
There are a set of n facilities and a set of n locations. For each pair of locations, a distance is specified and for each pair of facilities a weight or flow is specified (e.g., the amount of supplies transported between the two facilities). The problem is to assign all facilities to different locations with the goal of minimizing the sum of the distances multiplied by the corresponding flows.
Intuitively, the cost function encourages facilities with high flows between each other to be placed close together.
The problem statement resembles that of the assignment problem, except that the cost function is expressed in terms of quadratic inequalities, hence the name.
Formal mathematical definition
The formal definition of the quadratic assignment problem is as follows:
Given two sets, P ("facilities") and L ("locations"), of equal size, together with a weight function w : P × P → R and a distance function d : L × L → R. Find the bijection f : P → L ("assignment") such that the cost function:
is minimized.
Usually weight and distance functions are viewed as square real-valued matrices, so that the cost function is written down as:
In matrix notation:
whe
|
https://en.wikipedia.org/wiki/Bernstein%E2%80%93Sato%20polynomial
|
In mathematics, the Bernstein–Sato polynomial is a polynomial related to differential operators, introduced independently by and , . It is also known as the b-function, the b-polynomial, and the Bernstein polynomial, though it is not related to the Bernstein polynomials used in approximation theory. It has applications to singularity theory, monodromy theory, and quantum field theory.
gives an elementary introduction, while and give more advanced accounts.
Definition and properties
If is a polynomial in several variables, then there is a non-zero polynomial and a differential operator with polynomial coefficients such that
The Bernstein–Sato polynomial is the monic polynomial of smallest degree amongst such polynomials . Its existence can be shown using the notion of holonomic D-modules.
proved that all roots of the Bernstein–Sato polynomial are negative rational numbers.
The Bernstein–Sato polynomial can also be defined for products of powers of several polynomials . In this case it is a product of linear factors with rational coefficients.
generalized the Bernstein–Sato polynomial to arbitrary varieties.
Note, that the Bernstein–Sato polynomial can be computed algorithmically. However, such computations are hard in general. There are implementations of related algorithms in computer algebra systems RISA/Asir, Macaulay2, and SINGULAR.
presented algorithms to compute the Bernstein–Sato polynomial of an affine variety together with an implementation in t
|
https://en.wikipedia.org/wiki/Reductive%20elimination
|
Reductive elimination is an elementary step in organometallic chemistry in which the oxidation state of the metal center decreases while forming a new covalent bond between two ligands. It is the microscopic reverse of oxidative addition, and is often the product-forming step in many catalytic processes. Since oxidative addition and reductive elimination are reverse reactions, the same mechanisms apply for both processes, and the product equilibrium depends on the thermodynamics of both directions.
General information
Reductive elimination is often seen in higher oxidation states, and can involve a two-electron change at a single metal center (mononuclear) or a one-electron change at each of two metal centers (binuclear, dinuclear, or bimetallic).
For mononuclear reductive elimination, the oxidation state of the metal decreases by two, while the d-electron count of the metal increases by two. This pathway is common for d8 metals Ni(II), Pd(II), and Au(III) and d6 metals Pt(IV), Pd(IV), Ir(III), and Rh(III). Additionally, mononuclear reductive elimination requires that the groups being eliminated must be cis to one another on the metal center.
For binuclear reductive elimination, the oxidation state of each metal decreases by one, while the d-electron count of each metal increases by one. This type of reactivity is generally seen with first row metals, which prefer a one-unit change in oxidation state, but has been observed in both second and third row metals.
Mechanisms
|
https://en.wikipedia.org/wiki/Oxidative%20addition
|
Oxidative addition and reductive elimination are two important and related classes of reactions in organometallic chemistry. Oxidative addition is a process that increases both the oxidation state and coordination number of a metal centre. Oxidative addition is often a step in catalytic cycles, in conjunction with its reverse reaction, reductive elimination.
Role in transition metal chemistry
For transition metals, oxidative reaction results in the decrease in the dn to a configuration with fewer electrons, often 2e fewer. Oxidative addition is favored for metals that are (i) basic and/or (ii) easily oxidized. Metals with a relatively low oxidation state often satisfy one of these requirements, but even high oxidation state metals undergo oxidative addition, as illustrated by the oxidation of Pt(II) with chlorine:
[PtCl4]2− + Cl2 → [PtCl6]2−
In classical organometallic chemistry, the formal oxidation state of the metal and the electron count of the complex both increase by two. One-electron changes are also possible and in fact some oxidative addition reactions proceed via series of 1e changes. Although oxidative additions can occur with the insertion of a metal into many different substrates, oxidative additions are most commonly seen with H–H, H–X, and C–X bonds because these substrates are most relevant to commercial applications.
Oxidative addition requires that the metal complex have a vacant coordination site. For this reason, oxidative additions are common for four
|
https://en.wikipedia.org/wiki/HCL
|
HCL may refer to:
Science and medicine
Hairy cell leukemia, an uncommon and slowly progressing B cell leukemia
Harvard Cyclotron Laboratory, from 1961 to 2002, a proton accelerator used for research and development
Hollow-cathode lamp, a spectral line source used in physics and chemistry
Hydrochloric acid, a solution of hydrogen chloride in water
Hydrochloride, the salt of hydrochloric acid and an organic base
Hydrogen chloride, chemical formula HCl
Hypomania Checklist, a questionnaire used to screen for hypomania and bipolar spectrum disorders
HCL color space, a color space model designed to accord with human perception of color
Computing
Hardware compatibility list
HashiCorp Configuration Language, a configuration language authored by HashiCorp, used by cloud infrastructure automation tools, such as Terraform.
Organizations
HCLTech, an IT outsourcing firm based in Noida, India
HCL Axon, a subsidiary of HCL Technologies
Hennepin County Library
Hindustan Cables Limited, an Indian cable manufacturer
Harvard College Library
HC Lugano, a Swiss professional ice hockey team based in Lugano
Honolulu Control Facility, an air traffic control facility
Horizon Coach Lines, an American bus company
See also
HCI (disambiguation)
|
https://en.wikipedia.org/wiki/Trimer%20%28chemistry%29
|
In chemistry, a trimer (; ) is a molecule or polyatomic anion formed by combination or association of three molecules or ions of the same substance. In technical jargon, a trimer is a kind of oligomer derived from three identical precursors often in competition with polymerization.
Examples
Alkyne trimerisation
In 1866, Marcellin Berthelot reported the first example of cyclotrimerization, the conversion of acetylene to benzene. This process was commercialized:
Nitrile trimerization
Symmetrical 1,3,5-triazines are prepared by trimerization of certain nitriles such as cyanogen chloride or cyanimide.
Cyanogen chloride and cyanogen bromide each trimerize at elevated temperatures over a carbon catalyst. The chloride gives cyanuric chloride:
The bromide has an extended shelflife when refrigerated. Like the chloride, it undergoes ab exothermic trimerisation to form cyanuric bromide. This reaction is catalyzed by traces of bromine, metal salts, acids and bases. For this reason, experimentalists avoid brownish samples.
An industrial route to cyanuric acid entails the thermal decomposition of urea, with release of ammonia. The conversion commences at approximately 175 °C:
3 H2N-CO-NH2 -> [C(O)NH]3 + 3 NH3
The endothermic synthesis of melamine can be understood in two steps.
First, urea decomposes into cyanic acid and ammonia in an endothermic reaction:
(NH2)2CO -> HOCN + NH3
Then in the second step, cyanic acid polymerizes to form cyanuric acid, which condenses with the li
|
https://en.wikipedia.org/wiki/Actor%20model
|
The actor model in computer science is a mathematical model of concurrent computation that treats an actor as the basic building block of concurrent computation. In response to a message it receives, an actor can: make local decisions, create more actors, send more messages, and determine how to respond to the next message received. Actors may modify their own private state, but can only affect each other indirectly through messaging (removing the need for lock-based synchronization).
The actor model originated in 1973. It has been used both as a framework for a theoretical understanding of computation and as the theoretical basis for several practical implementations of concurrent systems. The relationship of the model to other work is discussed in actor model and process calculi.
History
According to Carl Hewitt, unlike previous models of computation, the actor model was inspired by physics, including general relativity and quantum mechanics. It was also influenced by the programming languages Lisp, Simula, early versions of Smalltalk, capability-based systems, and packet switching. Its development was "motivated by the prospect of highly parallel computing machines consisting of dozens, hundreds, or even thousands of independent microprocessors, each with its own local memory and communications processor, communicating via a high-performance communications network." Since that time, the advent of massive concurrency through multi-core and manycore computer architecture
|
https://en.wikipedia.org/wiki/Complete%20set%20of%20commuting%20observables
|
In quantum mechanics, a complete set of commuting observables (CSCO) is a set of commuting operators whose common eigenvectors can be used as a basis to express any quantum state. In the case of operators with discrete spectra, a CSCO is a set of commuting observables whose simultaneous eigenspaces span the Hilbert space, so that the eigenvectors are uniquely specified by the corresponding sets of eigenvalues.
Since each pair of observables in the set commutes, the observables are all compatible so that the measurement of one observable has no effect on the result of measuring another observable in the set. It is therefore not necessary to specify the order in which the different observables are measured. Measurement of the complete set of observables constitutes a complete measurement, in the sense that it projects the quantum state of the system onto a unique and known vector in the basis defined by the set of operators. That is, to prepare the completely specified state, we have to take any state arbitrarily, and then perform a succession of measurements corresponding to all the observables in the set, until it becomes a uniquely specified vector in the Hilbert space (up to a phase).
The compatibility theorem
Consider two observables, and , represented by the operators and . Then the following statements are equivalent:
and are compatible observables.
and have a common eigenbasis.
The operators and commute, meaning that .
Proofs
Discussion
We consider the two
|
https://en.wikipedia.org/wiki/Bindu%20%28symbol%29
|
Bindu () is a Sanskrit word meaning "point", "drop" or "dot".
Philosophy
In Hindu metaphysics, Bindu is considered the point at which creation begins and may become unity. It is also described as "the sacred symbol of the cosmos in its unmanifested state". Bindu is the point around which the mandala is created, representing the Universe.
Bindu is often merged with [seed] (or sperm) and ova. In the Yogachudamani Upanishad Bindu is a duality, with a white Bindu representing shukla (pure) and a red Bindu representing maharaj (mastery). The white Bindu resides in the bindu visarga and is related to Shiva and the Moon, while the red Bindu resides in the muladhara chakra and is related to Shakti and the Sun. In yoga, the union of these two parts results in the ascension of kundalini to the sahasrara.
In Tibetan Buddhism Bindu is a component of the subtle body, which is composed of drops (Tibetan: ཐིག་ལེ thig le) and winds (Tibetan: རླུང rLung).
Chakra
In Tantra, Bindu (or Bindu visarga—"falling of the drop") is a point at the back of the head where Brahmins grow their tuft of hair. This point is below the sahasrara chakra and above the ajna chakra, and is represented by a crescent moon with a white drop. It represents the manifestation of creations such as consciousness.
The chakra is visualised as a lotus with 23 petals. Its symbol is the moon, which supports the growth of vegetation. Krishna said in the Bhagavad Gita XV/13, "Becoming the nectarine moon I nourish all plants
|
https://en.wikipedia.org/wiki/Velocimetry
|
Velocimetry is the measurement of the velocity of fluids. This is a task often taken for granted, and involves far more complex processes than one might expect. It is often used to solve fluid dynamics problems, study fluid networks, in industrial and process control applications, as well as in the creation of new kinds of fluid flow sensors. Methods of velocimetry include particle image velocimetry and particle tracking velocimetry, Molecular tagging velocimetry, laser-based interferometry, ultrasonic Doppler methods, Doppler sensors, and new signal processing methodologies.
In general, velocity measurements are made in the Lagrangian or Eulerian frames of reference (see Lagrangian and Eulerian coordinates). Lagrangian methods assign a velocity to a volume of fluid at a given time, whereas Eulerian methods assign a velocity to a volume of the measurement domain at a given time. A classic example of the distinction is particle tracking velocimetry, where the idea is to find the velocity of individual flow tracer particles (Lagrangian) and particle image velocimetry, where the objective is to find the average velocity within a sub-region of the field of view (Eulerian).
History
Velocimetry can be traced back to the days of Leonardo da Vinci, who would float grass seeds on a flow and sketch the resulting trajectories of the seeds that he observed (a Lagrangian measurement). Eventually da Vinci's flow visualizations were used in his cardio vascular studies, attempting to le
|
https://en.wikipedia.org/wiki/Flanders%20Mathematics%20Olympiad
|
The Flanders Mathematics Olympiad (; VWO) is a Flemish mathematics competition for students in grades 9 through 12. Two tiers of this competition exist: one for 9th- and 10th-graders (; JWO), and one for 11th- and 12th-graders. It is a feeder competition for the International Mathematical Olympiad.
History
The Olympiad was founded in 1985, replacing a system previously used since 1969 in which Flemish students were nominated to the IMO by their teachers. , 20,000 students participate annually.
In 2015, the founders of the Olympiad, Paul Igodt of the Katholieke Universiteit Leuven and Frank De Clerck of Ghent University, were given the career award for science communication of the Royal Flemish Academy of Belgium for Science and the Arts for their work.
Procedure
The competition lasts three rounds. During the first and second rounds, students must answer 30 multiple-choice mathematics problems. The first round occurs in schools, and the second round is organized by province, and is administered at various universities. The first round has a three-hour time limit for completion, the second round has a two-hour time limit.
The final round consists of four problems which require a detailed and coherent essay-type response. After the final round, three contestants are selected to compete in the International Mathematical Olympiad, making up half of the team from Belgium; the other half of the team comes from Wallonia.
References
External links
Official site (in Dutch)
In
|
https://en.wikipedia.org/wiki/VWO
|
VWO may refer to:
Vlaamse Wiskunde Olympiade, a Flemish mathematics competition
Voorbereidend wetenschappelijk onderwijs, a Dutch school system
Voluntary welfare organisation, charitable organisation
|
https://en.wikipedia.org/wiki/Geometric%20invariant%20theory
|
In mathematics, geometric invariant theory (or GIT) is a method for constructing quotients by group actions in algebraic geometry, used to construct moduli spaces. It was developed by David Mumford in 1965, using ideas from the paper in classical invariant theory.
Geometric invariant theory studies an action of a group on an algebraic variety (or scheme) and provides techniques for forming the 'quotient' of by as a scheme with reasonable properties. One motivation was to construct moduli spaces in algebraic geometry as quotients of schemes parametrizing marked objects. In the 1970s and 1980s the theory developed interactions with symplectic geometry and equivariant topology, and was used to construct moduli spaces of objects in differential geometry, such as instantons and monopoles.
Background
Invariant theory is concerned with a group action of a group on an algebraic variety (or a scheme) . Classical invariant theory addresses the situation when is a vector space and is either a finite group, or one of the classical Lie groups that acts linearly on . This action induces a linear action of on the space of polynomial functions on by the formula
The polynomial invariants of the -action on are those polynomial functions on which are fixed under the 'change of variables' due to the action of the group, so that for all in . They form a commutative algebra , and this algebra is interpreted as the algebra of functions on the 'invariant theory quotient'
|
https://en.wikipedia.org/wiki/System%20Planning%20Corporation
|
System Planning Corporation (SPC) is a Virginia-based corporation founded in 1970 that produces military electronics, such as flight control systems, radar, and Systems Engineering and Technical Assistance in airwarfare, cybersecurity, program management and research of advanced weapons systems, advanced space systems and advanced microsystems for the United States Department of Defense (DoD). SPC was acquired by ECS Federal, LLC in 2015. It is principal support contractor to cabinet-level departments, including the Department of Defense, Justice and State, and Homeland Security.
History
SPC had its direct predecessor Systems Planning and Research Corporation, headquartered in Maryland, which started its R&D activities in the 1950s from development of the advanced range instrumentation systems for the U.S. Army missile ranges.
The conference room of SPC was also used for meetings of the Society for Operational Research, to which Viktor Vasilyevich Lozenko, a Soviet KGB officer under the cover of diplomat also belongs. In September 1980, Lozenko bugged the conference room and acquired highly important intelligence about the current and future deployment of US nuclear weapons in Europe, American chemical weapons, US navy's chances of survival in a nuclear conflict and US position on SAALT-2 talks and even Pentagon officials' classified report entitled Current Status and Trends in the Advancement of the US Nuclear Front in the Central European Theater of War in which US mobili
|
https://en.wikipedia.org/wiki/Cliff%20Hare
|
Clifford Leroy Hare was a member of Auburn University’s first football team who went on to serve as chair of the Auburn Faculty Athletic Committee. Auburn’s football stadium, Jordan–Hare Stadium, is co-named for the longtime professor and dean of the School of Chemistry. He served as president of the Southern Conference before the formation of the Southeastern Conference.
Biography
Clifford Leroy Hare was born in 1869, in what is now known as the Oak Bowery Community just north of Opelika, Alabama. In 1888, Hare began his one-half century relationship with Alabama Polytechnic Institute (API), which eventually became Auburn University.
Deeply involved in academics, athletics and policymaking at API, Cliff Hare’s biggest concern was for the development of the complete man. He strove to see that the young students who entered college there would have the opportunity to develop into well-rounded future citizens of Alabama. He often quoted Shakespeare in his chemistry classes, and he discussed philosophy with students and Auburn townspeople. His philosophy is summed up in an inscription on the Cliff Hare award, “Athletics make men strong, study makes men wise, and character makes men great.” This belief manifested itself in how he approached his personal life. He was involved in teaching, mentoring and enabling well-governed sports events at the university, as well as working to improve his community.
Notable Accomplishments
Specific highlights of Dean Hare's career at
|
https://en.wikipedia.org/wiki/John%20Ross%20Bradfield
|
John Ross Bradfield, (1899 – October 29, 1983) was a Canadian businessman who was involved in the development of the Canadian mining industry as President and CEO of Noranda.
Born in Morrisburg, Ontario, he graduated from McGill University in 1922 with a Bachelor of Science degree in civil engineering. He was a field engineer on the construction of Yankee Stadium. He joined Noranda Mines in 1922. In 1927 he became a construction superintendent. Rising in the ranks of the company he became, in 1956, president and chief executive officer and chairman of the board and chief executive officer in 1962. He resigned as CEO in 1968 but remained as Chairman of the board until 1974.
In 1973 he was made a Companion of the Order of Canada "for his many contributions to the development of the mining industry and to the growth of the Canadian business community". He is also an inductee of the Canadian Mining Hall of Fame.
References
1899 births
1983 deaths
Canadian mining businesspeople
Companions of the Order of Canada
McGill University Faculty of Engineering alumni
People from the United Counties of Stormont, Dundas and Glengarry
|
https://en.wikipedia.org/wiki/MCB
|
MCB or mcb may refer to:
Science and technology
Molecular and Cellular Biology, a scientific journal
Monochlorobenzene, an organic solvent
Miniature circuit breaker, in electrical distribution boards
Manually Controlled Barriers, a type of level crossing in the UK
Organisations
Mauritius Commercial Bank, the oldest and largest banking institution in Mauritius
MCB Group, a financial services holding company based in Mauritius, Mauritius Commercial Bank's holding company
Muslim Commercial Bank, former name of MCB Bank Limited, a network of banks in Pakistan
Maidenhead Citadel Band, of The Salvation Army
Methodist College Belfast, a voluntary grammar school in Belfast, Northern Ireland
Muslim Council of Britain, an umbrella body for 500 mosques, schools and associations in Britain
Movimiento Continental Bolivariano, Spanish name of the Bolivarian Continental Movement, a left-wing political movement in Latin America
Transport
McComb (Amtrak station) (Amtrak station code), Mississippi, US
Moulsecoomb railway station, a railway station in Sussex, England
Other uses
Janney coupler or Master Car Builders coupler, a type railroad coupling
MCB Tower, a skyscraper in Pakistan, owned by MCB Bank Limited
See also
United States Marine Corps Bases:
Marine Corps Base Quantico
Marine Corps Base Camp Pendleton
|
https://en.wikipedia.org/wiki/Mathematical%20Kangaroo
|
Mathematical Kangaroo (also known as Kangaroo challenge, or jeu-concours Kangourou in French) is an international mathematics competition in over 77 countries. There are six levels of participation, ranging from grade 1 to grade 12. The competition is held annually on the third Thursday of March. The challenge consists of problems in multiple-choice form that are not standard notebook problems and come from a variety of topics. Besides basic computational skills, they require inspiring ideas, perseverance, creativity and imagination, logical thinking, and other problem-solving strategies. Often there are small stories, intriguing problems, and surprising results, which encourage discussions with friends and family.
It had over 6 million participants from 57 countries in 2014. In 2022, it has 84 participants countries and claims to be the largest competition for school students in the world.
History
Mathematicians in Australia came up with the idea to organize a competition that underlines the joy of mathematics and encourages mathematical problem-solving. A multiple-choice competition was created, which has been taking place in Australia since 1978. At the same time, both in France and all over the world, a widely supported movement emerged towards the popularization of mathematics. The idea of a multiple-choice competition then sprouted from two French teachers, André Deledicq and Jean Pierre Boudine, who visited their Australian colleagues Peter O’Holloran and Peter Ta
|
https://en.wikipedia.org/wiki/Joseph%20Achille%20Le%20Bel
|
Joseph Achille Le Bel (21 January 1847 in Pechelbronn – 6 August 1930, in Paris, France) was a French chemist. He is best known for his work in stereochemistry. Le Bel was educated at the École Polytechnique in Paris. In 1874 he announced his theory outlining the relationship between molecular structure and optical activity. This discovery laid the foundation of the science of stereochemistry, which deals with the spatial arrangement of atoms in molecules. This hypothesis was put forward in the same year by the Dutch physical chemist Jacobus Henricus van 't Hoff and is currently known as Le Bel–van't Hoff rule. Le Bel wrote Cosmologie Rationelle (Rational Cosmology) in 1929.
Works
See also
Hexamethylbenzene
Optical rotation
References
Royal Society of Chemistry obituary
1847 births
1930 deaths
19th-century French chemists
Members of the French Academy of Sciences
Foreign Members of the Royal Society
Stereochemists
People from Bas-Rhin
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.