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https://en.wikipedia.org/wiki/Thomas%20William%20Moffett
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Sir Thomas William Moffett (3 June 1820 – 6 July 1908) was an Irish scholar and educationalist, who served as president of Queen's College Galway.
Moffett was born at Castleknock, County Dublin, on 3 June 1820. He was educated at Trinity College Dublin, where he was a Berkeley Gold Medallist in Logic and Metaphysics, a gold medallist in Greek, and a prizeman in Divinity and Modern History. He graduated in 1843 as Senior Moderator in Ethics and Logic. He was awarded the degree of L.L.D. by Trinity College Dublin in 1852.
From May 1848, he held the position of headmaster of the Classical Department and professor of logic and belles lettres at the Royal Belfast Academical Institution. The first professors were appointed to the newly established Queen's Colleges at Belfast, Cork and Galway in 1849, and Moffett became the foundation professor of logic and metaphysics at the Galway College. In 1863, in addition to his original chair, Moffett took over the duties of Rev. Joseph O'Leary as professor of history and English literature, the offices being combined into a single chair of history, English literature and mental science. Moffett was to occupy this chair until his retirement from academia in 1897.
In 1870, Moffett succeeded William Lupton as registrar of Queen's College Galway. On the death of Edward Berwick in 1877, Moffett was appointed to succeed him as president of the college.
Moffett was noted for his skill and power as an orator, and his ability to quote at will lo
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https://en.wikipedia.org/wiki/Chartered%20Chemist
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Chartered Chemist (CChem) is a chartered status awarded by the Royal Society of Chemistry (RSC) in the United Kingdom, the Royal Australian Chemical Institute (RACI) in Australia, by the Ministry of Education in Italy, the Institute of Chemistry Ceylon (IChemC), Sri Lanka, and the Institute of Chartered Chemists of Nigeria in Nigeria.
Achieving chartered status in any profession denotes to the wider community a high level of specialised subject knowledge and professional competence. The award of the Chartered Chemist (CChem) designation recognises the experienced practising chemist who has demonstrated an in-depth knowledge of chemistry, significant personal achievements based upon chemistry, professionalism in the workplace and a commitment to maintaining technical expertise through continuing professional development.
UK
In the United Kingdom, CChem candidates must meet the following requirements:
Be a Member or a Fellow of the RSC;
Hold a Master level accredited degree by the RSC (or equivalent);
Show that the chemical science knowledge and skills acquired from their education and training are essential for fulfilling the needs of their job;
Demonstrate development of 14 Professional Attributes.
The 14 professional attributes for Chartered Chemist in the UK are divided into five sections. The full list of attributes is:
A. Demonstrate and develop your knowledge of the chemical sciences.
Use a high-level knowledge of the chemical sciences to inform decisions and
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https://en.wikipedia.org/wiki/Jean%20E.%20Sammet
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Jean E. Sammet (March 23, 1928 – May 20, 2017) was an American computer scientist who developed the FORMAC programming language in 1962. She was also one of the developers of the influential COBOL programming language.
She received her B.A. in Mathematics from Mount Holyoke College in 1948 and her M.A. in Mathematics from University of Illinois at Urbana-Champaign in 1949. She received an honorary D.Sc. from Mount Holyoke College in 1978.
Sammet was employed by Sperry Gyroscope from 1955 to 1958 where she supervised the first scientific programming group. From 1958 to 1961, she worked for Sylvania as a staff consultant for programming research and a member of the original COBOL group. She joined IBM in 1961 where she developed FORMAC, the first widely used computer language for symbolic manipulation of mathematical formulas. At IBM she researched the use of restricted English as a programming language and the use of natural language for mathematical programs. She was Programming Technology Planning Manager for the Federal Systems Division from 1968 to 1974, and was appointed Software Technology Manager in 1979.
Sammet founded the ACM Special Interest Committee on Symbolic and Algebraic Manipulation (SICSAM) in 1965 and was chair of the Special Interest Group on Programming Languages (SIGPLAN). She was the first female president of the ACM, from 1974 to 1976.
Early life
Jean E. Sammet was born on March 23, 1928, in New York City. Jean and her sister, Helen, were born
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https://en.wikipedia.org/wiki/Sam%20Schwartz
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Samuel I. Schwartz, also known as Gridlock Sam, is an American transportation engineer, formerly the New York City Traffic Commissioner, notable for popularizing the phrase "gridlock".
Life and career
Schartz was educated at Brooklyn College (BS Physics) and the University of Pennsylvania (MSCE), and first worked as a New York City cabbie before being hired by the City of New York in 1971. He served as NYC Traffic Commissioner from 1982 to 1986, and when the traffic department became subsumed by the Department of Transportation he held the second-in-command post of First Deputy Commissioner and Chief Engineer from 1986-1990. While employed with the city, he attempted to introduce bicycle lanes and public plazas. They were vetoed at the last minute by then-mayor John Lindsay. He earned the nickname Gridlock Sam during the 1980 transit strike when he developed a series of transportation contingency plans, called the Grid-Lock Prevention Program.
It was under Schwartz's watch that the city almost became the first city to implement congestion pricing. The city's bridges had not been tolled since 1911 and beginning in 1973 he worked with Mayor Lindsay to reintroduce them. Even with a change in leadership (Mayor Lindsay was replaced by Abe Beame in 1974) it looked like the tolls would be reinstated. However, an act of Congress nixed the proposal in 1977. See: Congestion pricing in New York City.
After he left city government around 1996, he started his own firm. He writes column
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https://en.wikipedia.org/wiki/Blattner%27s%20conjecture
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In mathematics, Blattner's conjecture or Blattner's formula is a description of the discrete series representations of a general semisimple group G in terms of their restricted representations to a maximal compact subgroup K (their so-called K-types). It is named after Robert James Blattner, despite not being formulated as a conjecture by him.
Statement
Blattner's formula says that if a discrete series representation with infinitesimal character λ is restricted to a maximal compact subgroup K, then the representation of K with highest weight μ occurs with multiplicity
where
Q is the number of ways a vector can be written as a sum of non-compact positive roots
WK is the Weyl group of K
ρc is half the sum of the compact roots
ρn is half the sum of the non-compact roots
ε is the sign character of WK.
Blattner's formula is what one gets by formally restricting the Harish-Chandra character formula for a discrete series representation to the maximal torus of a maximal compact group. The problem in proving the Blattner formula is that this only gives the character on the regular elements of the maximal torus, and one also needs to control its behavior on the singular elements. For non-discrete irreducible representations the formal restriction of Harish-Chandra's character formula need not give the decomposition under the maximal compact subgroup: for example, for the principal series representations of SL2 the character is identically zero on the non-singular elements of the ma
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https://en.wikipedia.org/wiki/Thioketone
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In organic chemistry, thioketones (; also known as thiones or thiocarbonyls) are organosulfur compounds related to conventional ketones in which the oxygen has been replaced by a sulfur. Instead of a structure of , thioketones have the structure , which is reflected by the prefix "thio-" in the name of the functional group. Thus the simplest thioketone is thioacetone, the sulfur analog of acetone. Unhindered alkylthioketones typically tend to form polymers or rings.
Structure and bonding
The C=S bond length of thiobenzophenone is 1.63 Å, which is comparable to 1.64 Å, the C=S bond length of thioformaldehyde, measured in the gas phase. Due to steric interactions, the phenyl groups are not coplanar and the dihedral angle SC-CC is 36°. Unhindered dialkylthiones polymerize or oligomerize but thiocamphor is well characterized red solid.
Consistent with the double bond rule, most alkyl thioketones are unstable with respect to dimerization. The energy difference between the p orbitals of sulfur and carbon is greater than that between oxygen and carbon in ketones. The relative difference in energy and diffusity of the atomic orbitals of sulfur compared with carbon results in poor overlap of the atomic orbitals and the energy gap between the HOMO and LUMO is thus reduced for C=S molecular orbitals relative to C=O. The striking blue appearance of thiobenzophenone is attributed to π→ π* transitions upon the absorption of red light. Thiocamphor is red.
Preparative methods
Thiones ar
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https://en.wikipedia.org/wiki/Theodor%20Curtius
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Geheimrat Julius Wilhelm Theodor Curtius (27 May 1857 – 8 February 1928) was professor of Chemistry at Heidelberg University and elsewhere. He published the Curtius rearrangement in 1890/1894 and also discovered diazoacetic acid, hydrazine and hydrazoic acid.In 1882 he carried out the first ever peptide synthesis, creating the N-protected dipeptide, benzoylglycylglycine
History
Theodor Curtius was born in Duisburg in the Ruhr area in Germany. He studied chemistry with Robert Bunsen at Heidelberg University and with Hermann Kolbe at Leipzig University. He received his doctorate in 1882 in Leipzig.
After working from 1884 to 1886 for Adolf von Baeyer at the University of Munich, Curtius became the director of the analytical chemistry department at University of Erlangen until 1889. Then he accepted the chair in Chemistry at the University of Kiel, where he remained very productive. In line with this success, Curtius was appointed Geheimer Regierungsrat (Privy Councillor) in 1895. After a one-year appointment as the successor of the famous August Kekulé at Bonn University in 1897, Curtius succeeded Victor Meyer as Professor of Chemistry at his old university in Heidelberg in 1898, where he remained until his retirement in 1926. He was succeeded by Karl Freudenberg, who wrote Curtius' biography in 1962.
In his free time, he also composed music, sang in concerts, and was an active mountaineer. In 1894 he founded the Kiel section of the Association of German and Austrian Alpini
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https://en.wikipedia.org/wiki/Jean%20Fr%C3%A9chet
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Jean M.J. Fréchet (born August 1944) is a French-American chemist and professor emeritus at the University of California, Berkeley. He is best known for his work on polymers including polymer-supported chemistry, chemically amplified photoresists, dendrimers, macroporous separation media, and polymers for therapeutics. Ranked among the top 10 chemists in 2021, he has authored nearly 900 scientific paper and 200 patents including 96 US patents. His research areas include organic synthesis and polymer chemistry applied to nanoscience and nanotechnology with emphasis on the design, fundamental understanding, synthesis, and applications of functional macromolecules.
Fréchet is an elected fellow of the American Association for the Advancement of Science, the American Chemical Society, and the American Academy of Arts and Sciences, and an elected member of the US National Academy of Sciences, the US National Academy of Engineering, and the Academy of Europe (Academia Europaea).
Education and academic career
Fréchet received his first university degree at the Institut de Chimie et Physique Industrielles (now CPE) in Lyon, France, before coming to the US for studies in organic and polymer chemistry under Conrad Schuerch at the State University of New York College of Environmental Science and Forestry, and at Syracuse University (Ph.D. 1971). He was on the Chemistry Faculty at the University of Ottawa in Canada from 1973 to 1987, when he became the IBM Professor of Polymer Ch
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https://en.wikipedia.org/wiki/Time%20reversal%20signal%20processing
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Time reversal signal processing is a signal processing technique that has three main uses: creating an optimal carrier signal for communication, reconstructing a source event, and focusing high-energy waves to a point in space. A Time Reversal Mirror (TRM) is a device that can focus waves using the time reversal method. TRMs are also known as time reversal mirror arrays since they are usually arrays of transducers. TRM are well-known and have been used for decades in the optical domain. They are also used in the ultrasonic domain.
Overview
If the source is passive, i.e. some type of isolated reflector, an iterative technique can be used to focus energy on it. The TRM transmits a plane wave which travels toward the target and is reflected off it. The reflected wave returns to the TRM, where it looks as if the target has emitted a (weak) signal. The TRM reverses and retransmits the signal as usual, and a more focused wave travels toward the target. As the process is repeated, the waves become more and more focused on the target.
Yet another variation is to use a single transducer and an ergodic cavity. Intuitively, an ergodic cavity is one that will allow a wave originating at any point to reach any other point. An example of an ergodic cavity is an irregularly shaped swimming pool: if someone dives in, eventually the entire surface will be rippling with no clear pattern. If the propagation medium is lossless and the boundaries are perfect reflectors, a wave starting
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https://en.wikipedia.org/wiki/Solvable%20Lie%20algebra
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In mathematics, a Lie algebra is solvable if its derived series terminates in the zero subalgebra. The derived Lie algebra of the Lie algebra is the subalgebra of , denoted
that consists of all linear combinations of Lie brackets of pairs of elements of . The derived series is the sequence of subalgebras
If the derived series eventually arrives at the zero subalgebra, then the Lie algebra is called solvable. The derived series for Lie algebras is analogous to the derived series for commutator subgroups in group theory, and solvable Lie algebras are analogs of solvable groups.
Any nilpotent Lie algebra is a fortiori solvable but the converse is not true. The solvable Lie algebras and the semisimple Lie algebras form two large and generally complementary classes, as is shown by the Levi decomposition. The solvable Lie algebras are precisely those that can be obtained from semidirect products, starting from 0 and adding one dimension at a time.
A maximal solvable subalgebra is called a Borel subalgebra. The largest solvable ideal of a Lie algebra is called the radical.
Characterizations
Let be a finite-dimensional Lie algebra over a field of characteristic . The following are equivalent.
(i) is solvable.
(ii) , the adjoint representation of , is solvable.
(iii) There is a finite sequence of ideals of :
(iv) is nilpotent.
(v) For -dimensional, there is a finite sequence of subalgebras of :
with each an ideal in . A sequence of this type is called an elementary se
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https://en.wikipedia.org/wiki/Neochoerus
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Neochoerus ("new hog") is an extinct genus of rodent closely related to the living capybara. Fossil remains of Neochoerus have been found through North America (México and United States) and South America in Boyacá, Colombia.
References
Further reading
Paleobiology Database query for Neochoerus
Cavies
Pleistocene mammals of South America
Prehistoric rodent genera
Pleistocene rodents
Pleistocene genera
Pleistocene mammals of North America
Fossils of Colombia
Pleistocene Colombia
Altiplano Cundiboyacense
Fossil taxa described in 1926
Taxa named by William Perry Hay
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https://en.wikipedia.org/wiki/Hypokeimenon
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Hypokeimenon (Greek: ὑποκείμενον), later often material substratum, is a term in metaphysics which literally means the "underlying thing" (Latin: subiectum).
To search for the hypokeimenon is to search for that substance that persists in a thing going through change—its basic essence.
Overview
Aristotle defined a hypokeimenon in narrowly and purely grammatical terms, as something which cannot be a predicate of other things, but which can carry other things as its predicates.
The existence of a material substratum was posited by John Locke, with conceptual similarities to Baruch Spinoza's substance and Immanuel Kant's concept of the noumenon (in The Critique of Pure Reason).
Locke theorised that when all sensible properties were abstracted away from an object, such as its colour, weight, density or taste, there would still be something left to which the properties had adhered—something which allowed the object to exist independently of the sensible properties that it manifested in the beholder. Locke saw this ontological ingredient as necessary if one is to be able to consider objects as existing independently of one's own mind. The material substratum proved a difficult idea for Locke as by its very nature its existence could not be directly proven in the manner endorsed by empiricists (i.e., proof by exhibition in experience). Nevertheless, he believed that the philosophical reasons for it were strong enough for its existence to be considered proved.
The existence of t
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https://en.wikipedia.org/wiki/Single%20address%20space%20operating%20system
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In computer science, a single address space operating system (or SASOS) is an operating system that provides only one globally shared address space for all processes. In a single address space operating system, numerically identical (virtual memory) logical addresses in different processes all refer to exactly the same byte of data.
Single address-space operating systems offer certain advantages. In a traditional OS with private per-process address space, memory protection is based on address space boundaries ("address space isolation"). Single address-space operating systems use a different approach for memory protection that is just as strong. One advantage is that the same virtual-to-physical map page table can be used with every process (and in some SASOS, the kernel as well). This makes context switches on a SASOS faster than on operating systems that must change the page table and flush the TLB caches on every context switch.
SASOS projects include the following:
Amiga family – AmigaOS, AROS and MorphOS
Angel
BareMetal
Br1X
Genera by Symbolics
IBM i (formerly called OS/400)
Iguana at NICTA, Australia
JX a research Java OS
IncludeOS
Mungi at NICTA, Australia
Nemesis
Opal
OS-9
Phantom OS
RTEMS
Scout
Singularity
Sombrero
TempleOS
Theseus OS
Torsion
VxWorks
Zephyr
See also
Exokernel
Hybrid kernel
Kernel
Microkernel
Nanokernel
Unikernel
Flat memory model
Virtual memory
References
Bibliography
.
Operating systems
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https://en.wikipedia.org/wiki/Weil%20reciprocity%20law
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In mathematics, the Weil reciprocity law is a result of André Weil holding in the function field K(C) of an algebraic curve C over an algebraically closed field K. Given functions f and g in K(C), i.e. rational functions on C, then
f((g)) = g((f))
where the notation has this meaning: (h) is the divisor of the function h, or in other words the formal sum of its zeroes and poles counted with multiplicity; and a function applied to a formal sum means the product (with multiplicities, poles counting as a negative multiplicity) of the values of the function at the points of the divisor. With this definition there must be the side-condition, that the divisors of f and g have disjoint support (which can be removed).
In the case of the projective line, this can be proved by manipulations with the resultant of polynomials.
To remove the condition of disjoint support, for each point P on C a local symbol
(f, g)P
is defined, in such a way that the statement given is equivalent to saying that the product over all P of the local symbols is 1. When f and g both take the values 0 or ∞ at P, the definition is essentially in limiting or removable singularity terms, by considering (up to sign)
fagb
with a and b such that the function has neither a zero nor a pole at P. This is achieved by taking a to be the multiplicity of g at P, and −b the multiplicity of f at P. The definition is then
(f, g)P = (−1)ab fagb.
See for example Jean-Pierre Serre, Groupes algébriques et corps de classe
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https://en.wikipedia.org/wiki/Tang%20Chao%20%28physicist%29
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Tang Chao (; born 1958) is a Chair Professor of Physics and Systems Biology at Peking University.
Education
He had his undergraduate training at the University of Science and Technology of China, then went to the United States through the CUSPEA program organized by Professor T. D. Lee. He received a Ph.D. degree in Physics from the University of Chicago.
Career
In his early career, he worked on problems in statistical physics, dynamical system and complex systems. In 1987, along with Per Bak and Kurt Wiesenfeld, he proposed the concept and developed the theory for self-organized criticality, which had and continues to have broad applications in complex systems with scale invariance. The model they used to illustrate the idea is referred to as the Bak-Tang-Wiesenfeld "sandpile" model. His current research interest is at the interface between physics and biology. Specifically, he focuses on systems biology and works on problems such as protein folding, cell cycle regulation, function-topology relationship in biological network, cell fate determination and design principles in biological systems. He was a tenured Full Professor at the University of California San Francisco before returning to China in 2011. He is a Fellow of the American Physical Society, a member of the Chinese Academy of Sciences, the founding director of the interdisciplinary Center for Quantitative Biology at Peking University and the founding Co-Editor-in-Chief of the journal Quantitative Biology.
Sele
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https://en.wikipedia.org/wiki/Chemistry%20%28Girls%20Aloud%20album%29
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Chemistry is the third studio album by English-Irish girl group Girls Aloud. It was released in the United Kingdom on 5 December 2005 by Polydor Records. After the success of What Will the Neighbours Say?, the album was again entirely produced by Brian Higgins and his production team Xenomania. Chemistry is a loose concept album which details celebrity lifestyle and "what it's like to be a twentysomething girl in London." A number of the songs avert the verse-chorus form typical of pop music.
Chemistry was universally acclaimed by a number of contemporary music critics upon its release. Despite a relatively low chart position (peaking at 11, the lowest charting release by the group), the album yielded four top ten singles and was certified platinum in the United Kingdom and Ireland, selling over 390,000 copies. The album was followed by the Chemistry Tour, which had Girls Aloud performing in arenas for the first time.
Conception
After the success of What Will the Neighbours Say?, which was solely produced by Brian Higgins and Xenomania, the production team was asked to create Girls Aloud's third studio album. Chemistry was entirely produced and written by Xenomania, apart from a cover of Dee C. Lee's "See the Day." The album was recorded in 2005, following the What Will the Neighbours Say...? Tour. Parts of the process were shown in the fly on the wall documentary Girls Aloud: Home Truths.
Music
Style and lyrics
Chemistry explores a more innovative approach to pop music,
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https://en.wikipedia.org/wiki/Beam%20emittance
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In accelerator physics, emittance is a property of a charged particle beam. It refers to the area occupied by the beam in a position-and-momentum phase space.
Each particle in a beam can be described by its position and momentum along each of three orthogonal axes, for a total of six position and momentum coordinates. When the position and momentum for a single axis are plotted on a two dimensional graph, the average spread of the coordinates on this plot are the emittance. As such, a beam will have three emittances, one along each axis, which can be described independently. As particle momentum along an axis is usually described as an angle relative to that axis, an area on a position-momentum plot will have dimensions of length × angle (for example, millimeters × milliradian).
Emittance is important for analysis of particle beams. As long as the beam is only subjected to conservative forces, Liouville's Theorem shows that emittance is a conserved quantity. If the distribution over phase space is represented as a cloud in a plot (see figure), emittance is the area of the cloud. A variety of more exact definitions handle the fuzzy borders of the cloud and the case of a cloud that does not have an elliptical shape. In addition, the emittance along each axis is independent unless the beam passes through beamline elements (such as solenoid magnets) which correlate them.
A low-emittance particle beam is a beam where the particles are confined to a small distance and have n
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https://en.wikipedia.org/wiki/Radiation%20damping
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Radiation damping in accelerator physics is a way of reducing the beam emittance of a high-velocity charged particle beam by synchrotron radiation.
The two main ways of using radiation damping to reduce the emittance of a particle beam are the use of undulators and damping rings (often containing undulators), both relying on the same principle of inducing synchrotron radiation to reduce the particles' momentum, then replacing the momentum only in the desired direction of motion.
Damping rings
As particles are moving in a closed orbit, the lateral acceleration causes them to emit synchrotron radiation, thereby reducing the size of their momentum vectors (relative to the design orbit) without changing their orientation (ignoring quantum effects for the moment). In longitudinal direction, the loss of particle impulse due to radiation is replaced by accelerating sections (RF cavities) that are installed in the beam path so that an equilibrium is reached at the design energy of the accelerator. Since this is not happening in transverse direction, where the emittance of the beam is only increased by the quantization of radiation losses (quantum effects), the transverse equilibrium emittance of the particle beam will be smaller with large radiation losses, compared to small radiation losses.
Because high orbit curvatures (low curvature radii) increase the emission of synchrotron radiation, damping rings are often small. If long beams with many particle bunches are needed to fill
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https://en.wikipedia.org/wiki/Einstein%20relation%20%28kinetic%20theory%29
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In physics (specifically, the kinetic theory of gases), the Einstein relation is a previously unexpected connection revealed independently by William Sutherland in 1904, Albert Einstein in 1905, and by Marian Smoluchowski in 1906 in their works on Brownian motion. The more general form of the equation in the classical case is
where
is the diffusion coefficient;
is the "mobility", or the ratio of the particle's terminal drift velocity to an applied force, ;
is the Boltzmann constant;
is the absolute temperature.
This equation is an early example of a fluctuation-dissipation relation.
Note that the equation above describes the classical case and should be modified when quantum effects are relevant.
Two frequently used important special forms of the relation are:
Einstein–Smoluchowski equation, for diffusion of charged particles:
Stokes–Einstein equation, for diffusion of spherical particles through a liquid with low Reynolds number:
Here
is the electrical charge of a particle;
is the electrical mobility of the charged particle;
is the dynamic viscosity;
is the radius of the spherical particle.
Special cases
Electrical mobility equation (classical case)
For a particle with electrical charge , its electrical mobility is related to its generalized mobility by the equation . The parameter is the ratio of the particle's terminal drift velocity to an applied electric field. Hence, the equation in the case of a charged particle is given as
where
is t
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https://en.wikipedia.org/wiki/Johnjoe%20McFadden
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Johnjoe McFadden (born 17 May 1956) is an Anglo-Irish scientist, academic and writer. He is Professor of Molecular Genetics at the University of Surrey, United Kingdom.
Life
McFadden was born in Donegal, Ireland but raised in the UK. He holds joint British and Irish Nationality. He obtained his BSc in Biochemistry University of London in 1977 and his PhD at Imperial College London in 1982. He went on to work on human genetic diseases and then infectious diseases, at St Mary's Hospital Medical School, London (1982–84) and St George's Hospital Medical School, London (1984–88) and then at the University of Surrey in Guildford, UK.
For more than a decade, McFadden has researched the genetics of microbes such as the agents of tuberculosis and meningitis and invented a test for the diagnosis of meningitis. He has published more than 100 articles in scientific journals on subjects as wide-ranging as bacterial genetics, tuberculosis, idiopathic diseases and computer modelling of evolution. He has contributed to more than a dozen books and has edited a book on the genetics of mycobacteria. He produced a widely reported artificial life computer model which modelled evolution in organisms.
McFadden has lectured extensively in the UK, Europe, the US and Japan and his work has been featured on radio, television and national newspaper articles particularly for the Guardian. His present post, which he has held since 2001, is Professor of Molecular Genetics at the University of Surrey. Li
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https://en.wikipedia.org/wiki/Tonelli%27s%20theorem
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In mathematics, Tonelli's theorem may refer to
Tonelli's theorem in measure theory, a successor of Fubini's theorem
Tonelli's theorem in functional analysis, a fundamental result on the weak lower semicontinuity of nonlinear functionals on Lp spaces
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https://en.wikipedia.org/wiki/OPN
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OPN may stand for:
Osteopontin, a glycoprotein secreted by osteoblasts
Object Process Network, a simulation model meta-language
Optics & Photonics News, a magazine
Oneohtrix Point Never, recording alias of musician Daniel Lopatin
Olivary pretectal nucleus, a nucleus in the pretectal area, or pretectum
In mathematics, odd perfect number
Ora pro Nobis, Latin phrase litt. meaning "pray for us", often abbreviated as OpN in prayer books and breviaries
Yamaha YM2203, a sound chip
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https://en.wikipedia.org/wiki/MPM
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MPM may refer to:
Biology
MPM (psychedelic), a psychedelic drug
Malignant Pleural Mesothelioma
Matrix population models
Computing and technology
MPM (automobile), an automobile built in Mount Pleasant, Michigan, 1914–1915
MP/M (Multi-Programming Monitor Control Program), a Digital Research operating system
Manufacturing process management, to define how products are to be manufactured
Manufacturing Programming Mode, a configuration mode of the BIOS on some HP computers
Material point method, a numerical technique to simulate the behavior of solids, liquids, gases
Microwave Power Module, a microwave device to amplify radio frequency signals
Request processing modes, a feature of the Apache HTTP Server
Apache MultiProcessing Modules, part of the Apache HTTP Server architecture
Education
Master of Project Management, a graduate degree
Master of Public Management
Master of Science in Project Management
Other uses
Maputo International Airport (IATA code: MPM), in Maputo, Mozambique
Marginal propensity to import
Measures per minute, a measure of musical tempo
Metra potential method, a means of describing, organizing, and planning a project
Mid-Pacific Mountains, an oceanic plateau in the Pacific Ocean
Milwaukee Public Museum
Moviment Patrijotti Maltin, a Maltese anti-immigration political party
Movimiento Peronista Montonero, Argentine guerrilla group the Montoneros
Mysore Paper Mills, at Bhadravathi in the Shimoga district of Karnataka state, India
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https://en.wikipedia.org/wiki/BHK
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BHK is a three-letter abbreviation that may refer to:
BHK interpretation of intuitionistic predicate logic
Baby hamster kidney cells used in molecular biology
Bachelor of Human Kinetics (BHk) degree.
Baltische Historische Kommission, organization dealing with history of Baltic Germans
Biblia Hebraica (Kittel), by Rudolf Kittel
British Hong Kong, a former colony in the Qing Dynasty and later in the People's Republic of China, now Hong Kong
Bush Hill Park railway station, London, UK, National Rail station code
Bukhara International Airport, Uzbekistan, IATA code
Prosperous Armenia, Armenian political party
Bedroom - Hall - Kitchen, as used in India to describe apartments: 2 BHK, 3 BHK… — see Wiktionary:BHK
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https://en.wikipedia.org/wiki/List%20of%20cognitive%20scientists
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Below are some notable researchers in cognitive science.
Computer science
Linguistics
Neuroscience
Philosophy
Psychology
Other categories
Alfredo Ardila (neuroscience, neuropsychology, anthropology, evolution of cognition)
Scott Atran (cognitive anthropology)
Joscha Bach (cognitive science)
Frederic Bartlett (psychology, social anthropology)
Justin L. Barrett (cognitive psychology, cognitive anthropology)
Marc Bekoff (biology, cognitive ethology, behavioral ecology)
Maurice Bloch (cognitive anthropology)
Maggie Boden (cognitive science)
Pascal Boyer (cognitive anthropology)
Per Aage Brandt (cognitive semiotics)
Brian Butterworth (speech, dyslexia, mathematics)
Michael Cole (comparative cognition, cognitive psychology, cultural psychology)
Frederick L. Coolidge (evolutionary cognitive archaeology, cognitive evolution, behavior genetics)
Roy D'Andrade (cognitive anthropology)
Terrence Deacon (neuroanthropology, linguistics)
Merlin Donald (psychology, anthropology, historical evolution of cognition)
Fernando Flores (computer science, philosophy)
John Gowlett (evolutionary cognitive archaeology, evolutionary anthropology)
Tom Griffiths (computer science, psychology)
Christopher Robert Hallpike (anthropology)
Yuval Noah Harari (cognitive evolution, philosophy of artificial intelligence)
Brian Hare (evolutionary anthropology, evolution of cognition)
Friedrich Hayek (cognitive psychology, philosophy of perception)
Cecilia Heyes (cognitive evolution)
Lu
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https://en.wikipedia.org/wiki/Dimensional%20transmutation
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In particle physics, dimensional transmutation is a physical mechanism providing a linkage between a dimensionless parameter and a dimensionful parameter.
In classical field theory, such as gauge theory in four-dimensional spacetime, the coupling constant is a dimensionless constant. However, upon quantization, logarithmic divergences in one-loop diagrams of perturbation theory imply that this "constant" actually depends on the typical energy scale of the processes under considerations, called the renormalization group (RG) scale. This "running" of the coupling is specified by the beta-function of the renormalization group.
Consequently, the interaction may be characterised by a dimensionful parameter , namely the value of the RG scale at which the coupling constant diverges. In the case of quantum chromodynamics, this energy scale is called the QCD scale, and its value 220 MeV supplants the role of the original dimensionless coupling constant in the form of the logarithm (at one-loop) of the ratio and . Perturbation theory, which produced this type of running formula, is only valid for a (dimensionless) coupling ≪ 1. In the case of QCD, the energy scale is an infrared cutoff, such that implies , with the RG scale.
On the other hand, in the case of theories such as QED, is an ultraviolet cutoff, such that implies .
This is also a way of saying that the conformal symmetry of the classical theory is anomalously broken upon quantization, thereby setting up a mas
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https://en.wikipedia.org/wiki/Momentum%20transfer
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In particle physics, wave mechanics, and optics, momentum transfer is the amount of momentum that one particle gives to another particle. It is also called the scattering vector as it describes the transfer of wavevector in wave mechanics.
In the simplest example of scattering of two colliding particles with initial momenta , resulting in final momenta , the momentum transfer is given by
where the last identity expresses momentum conservation. Momentum transfer is an important quantity because is a better measure for the typical distance resolution of the reaction than the momenta themselves.
Wave mechanics and optics
A wave has a momentum and is a vectorial quantity. The difference of the momentum of the scattered wave to the incident wave is called momentum transfer. The wave number k is the absolute of the wave vector and is related to the wavelength . Momentum transfer is given in wavenumber units in reciprocal space
Diffraction
The momentum transfer plays an important role in the evaluation of neutron, X-ray, and electron diffraction for the investigation of condensed matter. Laue-Bragg diffraction occurs on the atomic crystal lattice, conserves the wave energy and thus is called elastic scattering, where the wave numbers final and incident particles, and , respectively, are equal and just the direction changes by a reciprocal lattice vector with the relation to the lattice spacing . As momentum is conserved, the transfer of momentum occurs to crystal momentum.
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https://en.wikipedia.org/wiki/Split%20supersymmetry
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In particle physics, split supersymmetry is a proposal for physics beyond the Standard Model.
History
It was proposed separately in three papers. The first by James Wells in June 2003 in a more modest form that mildly relaxed the assumption about naturalness in the Higgs potential. In May 2004 Nima Arkani-Hamed and Savas Dimopoulos argued that naturalness in the Higgs sector may not be an accurate guide to propose new physics beyond the Standard Model and argued that supersymmetry may be realized in a different fashion that preserved gauge coupling unification and has a dark matter candidate. In June 2004 Gian Giudice and Andrea Romanino argued from a general point of view that if one wants gauge coupling unification and a dark matter candidate, that split supersymmetry is one amongst a few theories that exists.
Overview
The new light (~TeV) particles in Split Supersymmetry (beyond the Standard Models particles) are
The Lagrangian for Split Supersymmetry is constrained from the existence of high energy supersymmetry. There are five couplings in Split Supersymmetry: the Higgs quartic coupling and four Yukawa couplings between the Higgsinos, Higgs and gauginos. The couplings are set by one parameter, , at the scale where the supersymmetric scalars decouple. Beneath the supersymmetry breaking scale, these five couplings evolve through the renormalization group equation down to the TeV scale. At a future Linear collider, these couplings could be measured at the 1% level
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https://en.wikipedia.org/wiki/Penrose%20graphical%20notation
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In mathematics and physics, Penrose graphical notation or tensor diagram notation is a (usually handwritten) visual depiction of multilinear functions or tensors proposed by Roger Penrose in 1971. A diagram in the notation consists of several shapes linked together by lines.
The notation widely appears in modern quantum theory, particularly in matrix product states and quantum circuits. In particular, Categorical quantum mechanics which includes ZX-calculus is a fully comprehensive reformulation of quantum theory in terms of Penrose diagrams, and is now widely used in quantum industry.
The notation has been studied extensively by Predrag Cvitanović, who used it, along with Feynman's diagrams and other related notations in developing "birdtracks", a group-theoretical diagram to classify the classical Lie groups. Penrose's notation has also been generalized using representation theory to spin networks in physics, and with the presence of matrix groups to trace diagrams in linear algebra.
Interpretations
Multilinear algebra
In the language of multilinear algebra, each shape represents a multilinear function. The lines attached to shapes represent the inputs or outputs of a function, and attaching shapes together in some way is essentially the composition of functions.
Tensors
In the language of tensor algebra, a particular tensor is associated with a particular shape with many lines projecting upwards and downwards, corresponding to abstract upper and lower indices o
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https://en.wikipedia.org/wiki/Diffeomorphism%20constraint
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In theoretical physics, it is often important to study theories with the diffeomorphism symmetry such as general relativity. These theories are invariant under arbitrary coordinate transformations. Equations of motion are generally derived from the requirement that the action is stationary. There are special variations that are equivalent to spatial diffeomorphisms. The invariance of the action under these variations implies non-dynamical equations of motion i.e. constraints. These equations must be satisfied or, at least, they must annihilate the physical states in a quantum version of the theory.
See also
Wheeler–DeWitt equation
Quantum gravity
Diffeomorphisms
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https://en.wikipedia.org/wiki/Higgs%20phase
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In theoretical physics, it is often important to consider gauge theory that admits many physical phenomena and "phases", connected by phase transitions, in which the vacuum may be found.
Global symmetries in a gauge theory may be broken by the Higgs mechanism. In more general theories such as those relevant in string theory, there are often many Higgs fields that transform in different representations of the gauge group.
If they transform in the adjoint representation or a similar representation, the original gauge symmetry is typically broken to a product of U(1) factors. Because U(1) describes electromagnetism including the Coulomb field, the corresponding phase is called a Coulomb phase.
If the Higgs fields that induce the spontaneous symmetry breaking transform in other representations, the Higgs mechanism often breaks the gauge group completely and no U(1) factors are left. In this case, the corresponding vacuum expectation values describe a Higgs phase.
Using the representation of a gauge theory in terms of a D-brane, for example D4-brane combined with D0-branes, the Coulomb phase describes D0-branes that have left the D4-branes and carry their own independent U(1) symmetries. The Higgs phase describes D0-branes dissolved in the D4-branes as instantons.
References
Gauge theories
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https://en.wikipedia.org/wiki/Chemische%20Berichte
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Chemische Berichte (usually abbreviated as Ber. or Chem. Ber.) was a German-language scientific journal of all disciplines of chemistry founded in 1868. It was one of the oldest scientific journals in chemistry, until it merged with Recueil des Travaux Chimiques des Pays-Bas to form Chemische Berichte/Recueil in 1997. Chemische Berichte/Recueil was then merged with other European journals in 1998 to form European Journal of Inorganic Chemistry.
History
Founded in 1868 as Berichte der Deutschen Chemischen Gesellschaft (, CODEN BDCGAS), it operated under this title until 1928 (Vol. 61). The journal was then split into:
Berichte der Deutschen Chemischen Gesellschaft, A: Vereins-Nachrichten (, CODEN BDCAAS), and
Berichte der Deutschen Chemischen Gesellschaft, B: Abhandlungen (, CODEN BDCBAD).
Vol. 78 and 79 (1945–1946) were omitted and not published due to World War II. The journal was renamed Chemische Berichte (, CODEN CHBEAM) in 1947 (Vol. 80) until 1996 (Vol. 129).
In 1997, Chemische Berichte and Liebigs Annalen were merged with the Dutch journal Recueil des Travaux Chimiques des Pays-Bas to form Chemische Berichte/Recueil (CODEN CHBRFW) and Liebigs Annalen/Recueil (CODEN LIARFV).
In 1998, Chemische Berichte/Recueil merged with other European journals to form European Journal of Inorganic Chemistry, while Liebigs Annalen/Recueil and other European journals were merged to form European Journal of Organic Chemistry.
External links
Homepage of the German Society of Ch
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https://en.wikipedia.org/wiki/Ber.
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The abbreviation Ber. may refer to:
Chemische Berichte, a German-language journal of chemistry
Berakhot (Talmud), a tractate of the Mishnah
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https://en.wikipedia.org/wiki/Tetrahedron%20%28journal%29
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Tetrahedron is a weekly peer-reviewed scientific journal covering the field of organic chemistry. According to the Journal Citation Reports, Tetrahedron has a 2020 impact factor of 2.457. Tetrahedron and Elsevier, its publisher, support an annual symposium. In 2010, complaints were raised over its high subscription cost.
Notable papers
, the Web of Science lists ten papers from Tetrahedron that have more than 1000 citations. The four articles that have been cited more than 2000 times are:
– cited 2228 times
– cited 2162 times
– cited 2124 times
– cited 2107 times
See also
Tetrahedron Letters
Tetrahedron Computer Methodology
Polyhedron (journal)
References
External links
Chemistry journals
Elsevier academic journals
Academic journals established in 1957
Weekly journals
English-language journals
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https://en.wikipedia.org/wiki/Observatory%20of%20Turin
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The Observatory of Turin (, also known as Pino Torinese; obs. code: 022) is an astronomical observatory owned and operated by Italy's National Institute for Astrophysics (, INAF). It is located on the top of a hill in the town of Pino Torinese near Turin, in the north Italian Piedmont region. The observatory was founded in 1759. At Pino Torinese, several asteroid discoveries were made by Italian astronomer Luigi Volta in the late 1920s and early 1930s. The asteroid 2694 Pino Torinese was named after the observatory's location.
Asteroids discovered at Pino Torinese
See also
List of astronomical observatories
References
External links
Osservatorio Astronomico di Torino
Torino
1759 establishments in Italy
Pino Torinese
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https://en.wikipedia.org/wiki/Dependence%20relation
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In mathematics, a dependence relation is a binary relation which generalizes the relation of linear dependence.
Let be a set. A (binary) relation between an element of and a subset of is called a dependence relation, written , if it satisfies the following properties:
if , then ;
if , then there is a finite subset of , such that ;
if is a subset of such that implies , then implies ;
if but for some , then .
Given a dependence relation on , a subset of is said to be independent if for all If , then is said to span if for every is said to be a basis of if is independent and spans
Remark. If is a non-empty set with a dependence relation , then always has a basis with respect to Furthermore, any two bases of have the same cardinality.
Examples
Let be a vector space over a field The relation , defined by if is in the subspace spanned by , is a dependence relation. This is equivalent to the definition of linear dependence.
Let be a field extension of Define by if is algebraic over Then is a dependence relation. This is equivalent to the definition of algebraic dependence.
See also
matroid
Linear algebra
Binary relations
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https://en.wikipedia.org/wiki/Nilpotent%20cone
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In mathematics, the nilpotent cone of a finite-dimensional semisimple Lie algebra is the set of elements that act nilpotently in all representations of In other words,
The nilpotent cone is an irreducible subvariety of (considered as a vector space).
Example
The nilpotent cone of , the Lie algebra of 2×2 matrices with vanishing trace, is the variety of all 2×2 traceless matrices with rank less than or equal to
References
.
.
Lie algebras
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https://en.wikipedia.org/wiki/Verma%20module
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Verma modules, named after Daya-Nand Verma, are objects in the representation theory of Lie algebras, a branch of mathematics.
Verma modules can be used in the classification of irreducible representations of a complex semisimple Lie algebra. Specifically, although Verma modules themselves are infinite dimensional, quotients of them can be used to construct finite-dimensional representations with highest weight , where is dominant and integral. Their homomorphisms correspond to invariant differential operators over flag manifolds.
Informal construction
We can explain the idea of a Verma module as follows. Let be a semisimple Lie algebra (over , for simplicity). Let be a fixed Cartan subalgebra of and let be the associated root system. Let be a fixed set of positive roots. For each , choose a nonzero element for the corresponding root space and a nonzero element in the root space . We think of the 's as "raising operators" and the 's as "lowering operators."
Now let be an arbitrary linear functional, not necessarily dominant or integral. Our goal is to construct a representation of with highest weight that is generated by a single nonzero vector with weight . The Verma module is one particular such highest-weight module, one that is maximal in the sense that every other highest-weight module with highest weight is a quotient of the Verma module. It will turn out that Verma modules are always infinite dimensional; if is dominant integral, however, one can co
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https://en.wikipedia.org/wiki/Lie%27s%20theorem
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In mathematics, specifically the theory of Lie algebras, Lie's theorem states that, over an algebraically closed field of characteristic zero, if is a finite-dimensional representation of a solvable Lie algebra, then there's a flag of invariant subspaces of with , meaning that for each and i.
Put in another way, the theorem says there is a basis for V such that all linear transformations in are represented by upper triangular matrices. This is a generalization of the result of Frobenius that commuting matrices are simultaneously upper triangularizable, as commuting matrices generate an abelian Lie algebra, which is a fortiori solvable.
A consequence of Lie's theorem is that any finite dimensional solvable Lie algebra over a field of characteristic 0 has a nilpotent derived algebra (see #Consequences). Also, to each flag in a finite-dimensional vector space V, there correspond a Borel subalgebra (that consist of linear transformations stabilizing the flag); thus, the theorem says that is contained in some Borel subalgebra of .
Counter-example
For algebraically closed fields of characteristic p>0 Lie's theorem holds provided the dimension of the representation is less than p (see the proof below), but can fail for representations of dimension p. An example is given by the 3-dimensional nilpotent Lie algebra spanned by 1, x, and d/dx acting on the p-dimensional vector space k[x]/(xp), which has no eigenvectors. Taking the semidirect product of this 3-dimensional Lie
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https://en.wikipedia.org/wiki/Superradiance
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In physics, superradiance is the radiation enhancement effects in several contexts including quantum mechanics, astrophysics and relativity.
Quantum optics
In quantum optics, superradiance is a phenomenon that occurs when a group of N emitters, such as excited atoms, interact with a common light field. If the wavelength of the light is much greater than the separation of the emitters, then the emitters interact with the light in a collective and coherent fashion. This causes the group to emit light as a high-intensity pulse (with rate proportional to N2). This is a surprising result, drastically different from the expected exponential decay (with rate proportional to N) of a group of independent atoms (see spontaneous emission). Superradiance has since been demonstrated in a wide variety of physical and chemical systems, such as quantum dot arrays and J-aggregates. This effect has been used to produce a superradiant laser.
Rotational superradiance
Rotational superradiance is associated with the acceleration or motion of a nearby body (which supplies the energy and momentum for the effect). It is also sometimes described as the consequence of an "effective" field differential around the body (e.g. the effect of tidal forces). This allows a body with a concentration of angular or linear momentum to move towards a lower energy state, even when there is no obvious classical mechanism for this to happen. In this sense, the effect has some similarities with quantum tunnelling
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https://en.wikipedia.org/wiki/Distribution%20%28differential%20geometry%29
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In differential geometry, a discipline within mathematics, a distribution on a manifold is an assignment of vector subspaces satisfying certain properties. In the most common situations, a distribution is asked to be a vector subbundle of the tangent bundle .
Distributions satisfying a further integrability condition give rise to foliations, i.e. partitions of the manifold into smaller submanifolds. These notions have several applications in many fields of mathematics, e.g. integrable systems, Poisson geometry, non-commutative geometry, sub-Riemannian geometry, differential topology, etc.
Even though they share the same name, distributions presented in this article have nothing to do with distributions in the sense of analysis.
Definition
Let be a smooth manifold; a (smooth) distribution assigns to any point a vector subspace in a smooth way. More precisely, consists in a collection of vector subspaces with the following property. Around any there exist a neighbourhood and a collection of vector fields such that, for any point , span
The set of smooth vector fields is also called a local basis of . Note that the number may be different for different neighbourhoods. The notation is used to denote both the assignment and the subset .
Regular distributions
Given an integer , a smooth distribution on is called regular of rank if all the subspaces have the same dimension. Locally, this amounts to ask that every local basis is given by linearly independen
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https://en.wikipedia.org/wiki/Harnack%27s%20inequality
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In mathematics, Harnack's inequality is an inequality relating the values of a positive harmonic function at two points, introduced by . Harnack's inequality is used to prove Harnack's theorem about the convergence of sequences of harmonic functions. , and generalized Harnack's inequality to solutions of elliptic or parabolic partial differential equations. Such results can be used to show the interior regularity of weak solutions.
Perelman's solution of the Poincaré conjecture uses a version of the Harnack inequality, found by , for the Ricci flow.
The statement
Harnack's inequality applies to a non-negative function f defined on a closed ball in Rn with radius R and centre x0. It states that, if f is continuous on the closed ball and harmonic on its interior, then for every point x with |x − x0| = r < R,
In the plane R2 (n = 2) the inequality can be written:
For general domains in the inequality can be stated as follows: If is a bounded domain with , then there is a constant such that
for every twice differentiable, harmonic and nonnegative function . The constant is independent of ; it depends only on the domains and .
Proof of Harnack's inequality in a ball
By Poisson's formula
where ωn − 1 is the area of the unit sphere in Rn and r = |x − x0|.
Since
the kernel in the integrand satisfies
Harnack's inequality follows by substituting this inequality in the above integral and using the fact that the average of a harmonic function over a sphere equals
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https://en.wikipedia.org/wiki/John%20E.%20Dennis
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John Emory Dennis, Jr. (born 1939) is an American mathematician who has made major contributions in mathematical optimization. Dennis is currently a Noah Harding professor emeritus and research professor in the department of computational and applied mathematics at Rice University in Houston, Texas. His research interests include optimization in engineering design. He is the founder and editor-in-chief of the SIAM Journal on Optimization. In 2010, he was elected a Fellow of the Society for Industrial and Applied Mathematics.
Education
Dennis earned a Bachelor of Science in Industrial Engineering (BSIE), in 1962 and a Master of Science in mathematics in 1964 at the University of Miami. He earned a Ph.D. in mathematics at the University of Utah in 1966.
Academic career
University of Utah, Department of Mathematics, Assistant Professor, 1966-1967
Cornell University, Department of Computer Science, full professor, 1969-1974
Rice University, Department of Computational and Applied Mathematics, full professor (retired), 1979-2007
At Rice, Dennis served as department chairman in both the Department of Computational and Applied Mathematics (CAAM) and Department of Computer Science (CS). He was also the chair of the Center for Research in Parallel Computing (CRPC) Optimization Project. He was the thesis director for 32 PhD students at Rice.
Publications
Books & monographs
On the matrix polynomial, lambda-matrix and block eigenvalue problems (1971). Pittsburgh, PA: Carneg
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https://en.wikipedia.org/wiki/Equivariant%20cohomology
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In mathematics, equivariant cohomology (or Borel cohomology) is a cohomology theory from algebraic topology which applies to topological spaces with a group action. It can be viewed as a common generalization of group cohomology and an ordinary cohomology theory. Specifically, the equivariant cohomology ring of a space with action of a topological group is defined as the ordinary cohomology ring with coefficient ring of the homotopy quotient :
If is the trivial group, this is the ordinary cohomology ring of , whereas if is contractible, it reduces to the cohomology ring of the classifying space (that is, the group cohomology of when G is finite.) If G acts freely on X, then the canonical map is a homotopy equivalence and so one gets:
Definitions
It is also possible to define the equivariant cohomology
of with coefficients in a
-module A; these are abelian groups.
This construction is the analogue of cohomology with local coefficients.
If X is a manifold, G a compact Lie group and is the field of real numbers or the field of complex numbers (the most typical situation), then the above cohomology may be computed using the so-called Cartan model (see equivariant differential forms.)
The construction should not be confused with other cohomology theories,
such as Bredon cohomology or the cohomology of invariant differential forms: if G is a compact Lie group, then, by the averaging argument, any form may be made invariant; thus, cohomology of invariant differen
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https://en.wikipedia.org/wiki/European%20Physical%20Journal
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The European Physical Journal (or EPJ) is a joint publication of EDP Sciences, Springer Science+Business Media, and the Società Italiana di Fisica. It arose in 1998 as a merger and continuation of Acta Physica Hungarica, Anales de Física, Czechoslovak Journal of Physics, Il Nuovo Cimento, Journal de Physique, Portugaliae Physica and Zeitschrift für Physik. The journal is published in various sections, covering all areas of physics.
History
In the late 1990s, Springer and EDP Sciences decided to merge Zeitschrift für Physik and Journal de Physique. With the addition of Il Nuovo Cimento from the Societa Italiana di Fisica, the European Physical Journal commenced publication in January 1998. Now EPJ is a merger and continuation of Acta Physica Hungarica, Anales de Fisica, Czechoslovak Journal of Physics, Il Nuovo Cimento, Journal de Physique, Portugaliae Physica and Zeitschrift für Physik.
The short-lived open-access journal family PhysMath Central was merged in 2011 into the European Physical Journal, which has offered an open-access option since 2006.
Topics covered
The EPJ is published in the following sections:
European Physical Journal A: Hadrons and Nuclei
: Applied Metamaterials
: Applied Physics
European Physical Journal B: Condensed Matter and Complex Systems
European Physical Journal C: Particles and Fields
European Physical Journal D: Atomic, Molecular, Optical and Plasma Physics
: Data Science
European Physical Journal E: Soft Matter and Biological Physic
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https://en.wikipedia.org/wiki/Ralph%20Pudritz
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Ralph E. Pudritz is a theoretical astrophysicist tenured at McMaster University in Hamilton, Ontario, Canada. He is an expert in the field of astrophysical jets, particularly those involved in star formation.
Professor Pudritz obtained his undergraduate degree at the University of British Columbia, and pursued graduate studies in physics at the University of Toronto and the University of British Columbia. He accepted a position at McMaster in 1986, and has since been on research leaves to the Max Planck Institute, the Center for Astrophysics Harvard & Smithsonian, Caltech among several others. The Long-Range Planning Council of the National Research Council of Canada chose Pudritz to chair its 1999 plan for the future of astrophysics in Canada. The Herzberg Institute of Astrophysics, the US National Radio Observatory and the NATO Institute for Advanced Study are a few of the organizations for which Pudritz has served as advisor.
In 2004 Pudritz spearheaded the formation of the Origins Institute, a multi-disciplinary scientific endeavour based at McMaster, and became its first director.
References
Academic staff of McMaster University
Harvard University staff
University of British Columbia alumni
University of Toronto alumni
Living people
Year of birth missing (living people)
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https://en.wikipedia.org/wiki/Sir%20George%20Stokes%20Award
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The Sir George Stokes Award (colloquially the Stokes Medal) is named after George Gabriel Stokes and is awarded biennially by the Analytical Division of the Royal Society of Chemistry. It was established in 1999 to recognize the multidisciplinary nature of analytical chemistry and is given:
There is no restriction on the nationality of those who can be considered for the award.
Winners
Source: Royal Society of Chemistry
See also
List of chemistry awards
References
Awards of the Royal Society of Chemistry
Awards established in 1999
1999 establishments in the United Kingdom
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https://en.wikipedia.org/wiki/Solomon%20H.%20Snyder
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Solomon Halbert Snyder (born December 26, 1938) is an American neuroscientist who has made wide-ranging contributions to neuropharmacology and neurochemistry. He studied at Georgetown University, and has conducted the majority of his research at the Johns Hopkins School of Medicine. Many advances in molecular neuroscience have stemmed from Snyder's identification of receptors for neurotransmitters and drugs, and elucidation of the actions of psychotropic agents. He received the Albert Lasker Award for Basic Medical Research in 1978 for his research on the opioid receptor, and is one of the most highly cited researchers in the biological and biomedical sciences, with the highest h-index in those fields for the years 1983–2002, and then from 2007 to 2019.
Biography
Personal life
Solomon Snyder was born on December 26, 1938, in Washington D.C. He is one of five children. Snyder and his wife Elaine, who died in 2016, have two daughters and three grandchildren. He lives in Baltimore, Maryland.
Education and early career
Snyder attended Georgetown University from 1955 to 1958 and received his M.D. degree from Georgetown University School of Medicine in 1962. After a medical residency at the Kaiser Hospital in San Francisco, he served as a research associate from 1963 to 1965 at the National Institutes of Health, where he studied under Julius Axelrod. Snyder moved to the Johns Hopkins University School of Medicine to complete his residency in psychiatry from 1965 to 1968. He wa
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https://en.wikipedia.org/wiki/Fangalabola
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Fangalabola (Deborrea malgassa) is a species of bagworm moth native to Madagascar.
These bagworms are of significance because their pupae are harvested for human consumption in quantity.
Biology
The length of the larvae is 30–40 mm, length of the bag 35–55 mm, the length of the female is approximately 25 mm.
It has a wingspan of 27–44 mm.//
Known foodplants are: Acacia dealbata, fruit trees, Hibiscus tiliaceus, Grevillea robusta, Dombeya spp., Psidium spp., Eucalyptus spp., Cupressus lusitanica, Pinus patala and Amygdalus persica.
This species occurs throughout the year in forested biotopes with reasonable humidity.
See also
List of moths of Madagascar
References
Psychidae
Lepidoptera of Madagascar
Moths described in 1884
Moths of Madagascar
Moths of Africa
Edible insects
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https://en.wikipedia.org/wiki/Hartogs%20number
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In mathematics, specifically in axiomatic set theory, a Hartogs number is an ordinal number associated with a set. In particular, if X is any set, then the Hartogs number of X is the least ordinal α such that there is no injection from α into X. If X can be well-ordered then the cardinal number of α is a minimal cardinal greater than that of X. If X cannot be well-ordered then there cannot be an injection from X to α. However, the cardinal number of α is still a minimal cardinal not less than or equal to the cardinality of X. (If we restrict to cardinal numbers of well-orderable sets then that of α is the smallest that is not not less than or equal to that of X.) The map taking X to α is sometimes called Hartogs's function. This mapping is used to construct the aleph numbers, which are all the cardinal numbers of infinite well-orderable sets.
The existence of the Hartogs number was proved by Friedrich Hartogs in 1915, using Zermelo–Fraenkel set theory alone (that is, without using the axiom of choice).
Hartogs's theorem
Hartogs's theorem states that for any set X, there exists an ordinal α such that ; that is, such that there is no injection from α to X. As ordinals are well-ordered, this immediately implies the existence of a Hartogs number for any set X. Furthermore, the proof is constructive and yields the Hartogs number of X.
Proof
See .
Let be the class of all ordinal numbers β for which an injective function exists from β into X.
First, we verify that α is a s
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https://en.wikipedia.org/wiki/N-skeleton
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In mathematics, particularly in algebraic topology, the of a topological space presented as a simplicial complex (resp. CW complex) refers to the subspace that is the union of the simplices of (resp. cells of ) of dimensions In other words, given an inductive definition of a complex, the is obtained by stopping at the .
These subspaces increase with . The is a discrete space, and the a topological graph. The skeletons of a space are used in obstruction theory, to construct spectral sequences by means of filtrations, and generally to make inductive arguments. They are particularly important when has infinite dimension, in the sense that the do not become constant as
In geometry
In geometry, a of P (functionally represented as skelk(P)) consists of all elements of dimension up to k.
For example:
skel0(cube) = 8 vertices
skel1(cube) = 8 vertices, 12 edges
skel2(cube) = 8 vertices, 12 edges, 6 square faces
For simplicial sets
The above definition of the skeleton of a simplicial complex is a particular case of the notion of skeleton of a simplicial set. Briefly speaking, a simplicial set can be described by a collection of sets , together with face and degeneracy maps between them satisfying a number of equations. The idea of the n-skeleton is to first discard the sets with and then to complete the collection of the with to the "smallest possible" simplicial set so that the resulting simplicial set contains no non-degenerate simplices in degrees .
Mo
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https://en.wikipedia.org/wiki/Charles%20%C3%89tienne%20Louis%20Camus
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Charles Étienne Louis Camus (25 August 1699 – 2 February 1768), was a French mathematician and mechanician who was born at Crécy-en-Brie, near Meaux.
He studied mathematics, civil and military architecture, and astronomy after leaving Collège de Navarre in Paris. In 1730 he was appointed professor of architecture and, in 1733, associate of the Académie des Sciences. He also became a professor of geometry, secretary to the Academy of Architecture and fellow of the Royal Society of London. In 1727 he presented a memoir to the academy on masting ships, in consequence of which he was named the same year joint mechanician to that body. In 1736 he accompanied Pierre Louis Maupertuis and Alexis Clairaut in the expedition to Lapland for the measurement of a degree of meridian arc. He was the author of a Cours de mathématiques (Paris, 1766), and a number of essays on mathematical and mechanical subjects.
In 1760 he became perpetual secretary of the academy of architecture. He was also employed in a variety of public works, and in 1765 was chosen a fellow of the Royal Society of London. He died in 1768.
Works
Traité des forces mouvantes ("Treatise of moving forces"); 1722.
Opérations faites pour mesurer le degré de méridienne entre Paris et Amiens; 1757.
Cours de mathématique ("Course of mathematics"); 3 parts, 1749–52.
Part 1: Élémens d'arithmétique (1749).
Part 2: Élémens de géométrie, théorique et pratique (1750).
Part 3: Élémens de méchanique statique (1751–52).
Externa
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https://en.wikipedia.org/wiki/Cyanocarbon
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In organic chemistry, cyanocarbons are a group of chemical compounds that contain several cyanide functional groups. Such substances generally are classified as organic compounds, since they are formally derived from hydrocarbons by replacing one or more hydrogen atoms with a cyanide group. One of the simplest member is (tetracyanomethane, also known as carbon tetracyanide). Organic chemists often refer to cyanides as nitriles.
In general, cyanide is an electronegative substituent. Thus, for example, cyanide-substituted carboxylic acids tend to be stronger than the parents. The cyanide group can also stabilize anions by delocalizing negative charge as revealed by resonance structures.
Definition and examples
Cyanocarbons are organic compounds bearing enough cyano functional groups to significantly alter their chemical properties.
Illustrative cyanocarbons:
Tetracyanoethylene, which reduces to a stable anion, unlike most derivatives of ethylene.
Pentacyanocyclopentadiene, which forms an air-stable anion, in contrast to cyclopentadiene.
Tetracyanoethylene oxide, an electrophilic epoxide that undergoes ready scission of its C-C bond.
Tetracyanoquinodimethane, , which reduces to a stable anion, unlike most quinones.
Cyanoform (tricyanomethane),
Pentacyanopropenide, .
References
Nitriles
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https://en.wikipedia.org/wiki/Cyclophane
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In organic chemistry, a cyclophane is a hydrocarbon consisting of an aromatic unit (typically a benzene ring) and a chain that forms a bridge between two non-adjacent positions of the aromatic ring. More complex derivatives with multiple aromatic units and bridges forming cagelike structures are also known. Cyclophanes are well-studied examples of strained organic compounds.
[n]-Cyclophanes
Structures
Paracyclophanes adopt the boat conformation normally observed in cyclohexanes. Smaller value of n lead to greater distortions. X-ray crystallography on '[6]paracyclophane' shows that the aromatic bridgehead carbon atom makes an angle of 20.5° with the plane. The benzyl carbons deviate by another 20.2°. The carbon-to-carbon bond length alternation has increased from 0 for benzene to 39 pm. Despite their distorted structures, cyclophanes retain their aromaticity, as determined by UV-vis spectroscopy.
Reactivity
With regards to their reactivity, cyclophanes often exhibit diene-like behavior, despite evidence for aromaticity in even the most distorted [6]-cyclophane. This highly distorted cyclophane photochemically converts to the Dewar benzene derivative. Heat reverses the reaction.
With dimethyl acetylenedicarboxylate, [6]metacyclophane rapidly undergoes the Diels-Alder reaction.
A non-bonding nitrogen to arene distance of 244 pm is recorded for a pyridinophane and in the unusual superphane the two benzene rings are separated by a mere 262 pm. Other representative of thi
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https://en.wikipedia.org/wiki/Cytochemistry
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Cytochemistry is the branch of cell biology dealing with the detection of cell constituents by means of biochemical analysis and visualization techniques. This is the study of the localization of cellular components through the use of staining methods. The term is also used to describe a process of identification of the biochemical content of cells. Cytochemistry is a science of localizing chemical components of cells and cell organelles on thin histological sections by using several techniques like enzyme localization, micro-incineration, micro-spectrophotometry, radioautography, cryo-electron microscopy, X-ray microanalysis by energy-dispersive X-ray spectroscopy, immunohistochemistry and cytochemistry, etc.
Freeze Fracture Enzyme Cytochemistry
Freeze fracture enzyme cytochemistry was initially mentioned in the study of Pinto de silva in 1987. It is a technique that allows the introduction of cytochemistry into a freeze fracture cell membrane. immunocytochemistry is used in this technique to label and visualize the cell membrane's molecules. This technique could be useful in analyzing the ultrastructure of cell membranes. The combination of immunocytochemistry and freeze fracture enzyme technique, research can identify and have a better understanding of the structure and distribution of a cell membrane.
Origin
Jean Brachet's research in Brussel demonstrated the localization and relative abundance between RNA and DNA in the cells of both animals and plants opened up the
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https://en.wikipedia.org/wiki/Hartogs%27s%20theorem%20on%20separate%20holomorphicity
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In mathematics, Hartogs's theorem is a fundamental result of Friedrich Hartogs in the theory of several complex variables. Roughly speaking, it states that a 'separately analytic' function is continuous. More precisely, if is a function which is analytic in each variable zi, 1 ≤ i ≤ n, while the other variables are held constant, then F is a continuous function.
A corollary is that the function F is then in fact an analytic function in the n-variable sense (i.e. that locally it has a Taylor expansion). Therefore, 'separate analyticity' and 'analyticity' are coincident notions, in the theory of several complex variables.
Starting with the extra hypothesis that the function is continuous (or bounded), the theorem is much easier to prove and in this form is known as Osgood's lemma.
There is no analogue of this theorem for real variables. If we assume that a function
is differentiable (or even analytic) in each variable separately, it is not true that will necessarily be continuous. A counterexample in two dimensions is given by
If in addition we define , this function has well-defined partial derivatives in and at the origin, but it is not continuous at origin. (Indeed, the limits along the lines and are not equal, so there is no way to extend the definition of to include the origin and have the function be continuous there.)
References
Steven G. Krantz. Function Theory of Several Complex Variables, AMS Chelsea Publishing, Providence, Rhode Island, 1992.
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https://en.wikipedia.org/wiki/Production%20rule
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Production rule may refer to:
Production rules used in business rule engines, cognitive modeling and artificial intelligence, see Production system
Production rules that expand nodes in formal grammars, see production (computer science)
Rules governing legal requests that documents be provided, see request for production
See also
Production Rule Representation, an OMG standard for production rules used in production systems
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https://en.wikipedia.org/wiki/%C3%89va%20Tardos
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Éva Tardos (born 1 October 1957) is a Hungarian mathematician and the Jacob Gould Schurman Professor of Computer Science at Cornell University.
Tardos's research interest is algorithms. Her work focuses on the design and analysis of efficient methods for combinatorial optimization problems on graphs or networks. She has done some work on network flow algorithms like approximation algorithms for network flows, cut, and clustering problems. Her recent work focuses on algorithmic game theory and simple auctions.
Education and career
Tardos received her Dipl. Math in 1981 and her Ph.D. 1984 from the Faculty of Sciences of the Eötvös Loránd University under her advisor András Frank. She was the Chair of the Department of Computer Science at Cornell from 2006-2010, and she is currently serving as the Associate Dean of the College of Computing and Information Science.
She was editor-in-Chief of SIAM Journal on Computing from 2004–2009, and is currently the Economics and Computation area editor of the Journal of the ACM as well as on the Board of Editors of Theory of Computing.
She has co-authored with Jon Kleinberg a textbook called Algorithm Design ().
Honors and awards
Tardos has been elected to the National Academy of Engineering (2007), the American Academy of Arts and Sciences, and the National Academy of Sciences (2013) and the American Philosophical Society (2020)
She is also an ACM Fellow (since 1998), a Fellow of INFORMS, and a Fellow of the American Mathematical Socie
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https://en.wikipedia.org/wiki/List%20of%20computer%20science%20conferences
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This is a list of academic conferences in computer science. Only conferences with separate articles are included; within each field, the conferences are listed alphabetically by their short names.
General
FCRC – Federated Computing Research Conference
Algorithms and theory
Conferences accepting a broad range of topics from theoretical computer science, including algorithms, data structures, computability, computational complexity, automata theory and formal languages:
CCC - Computational Complexity Conference
FCT – International Symposium on Fundamentals of Computation Theory
FOCS – IEEE Symposium on Foundations of Computer Science
ICALP – International Colloquium on Automata, Languages and Programming
ISAAC – International Symposium on Algorithms and Computation
MFCS – International Symposium on Mathematical Foundations of Computer Science
STACS – Symposium on Theoretical Aspects of Computer Science
STOC – ACM Symposium on Theory of Computing
WoLLIC – Workshop on Logic, Language, Information and Computation
Algorithms
Conferences whose topic is algorithms and data structures considered broadly, but that do not include other areas of theoretical computer science such as computational complexity theory:
ESA – European Symposium on Algorithms
SODA – ACM–SIAM Symposium on Discrete Algorithms
SWAT – Scandinavian Symposium and Workshops on Algorithm Theory
WADS – Algorithms and Data Structures Symposium
WAOA – Workshop on Approximation and Online Algorithms
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https://en.wikipedia.org/wiki/Minkowski%E2%80%93Hlawka%20theorem
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In mathematics, the Minkowski–Hlawka theorem is a result on the lattice packing of hyperspheres in dimension n > 1. It states that there is a lattice in Euclidean space of dimension n, such that the corresponding best packing of hyperspheres with centres at the lattice points has density Δ satisfying
with ζ the Riemann zeta function. Here as n → ∞, ζ(n) → 1. The proof of this theorem is indirect and does not give an explicit example, however, and there is still no known simple and explicit way to construct lattices with packing densities exceeding this bound for arbitrary n. In principle one can find explicit examples: for example, even just picking a few "random" lattices will work with high probability. The problem is that testing these lattices to see if they are solutions requires finding their shortest vectors, and the number of cases to check grows very fast with the dimension, so this could take a very long time.
This result was stated without proof by and proved by . The result is related to a linear lower bound for the Hermite constant.
Siegel's theorem
proved the following generalization of the Minkowski–Hlawka theorem. If S is a bounded set in Rn with Jordan volume vol(S) then the average number of nonzero lattice vectors in S is vol(S)/D, where the average is taken over all lattices with a fundamental domain of volume D, and similarly the average number of primitive lattice vectors in S is vol(S)/Dζ(n).
The Minkowski–Hlawka theorem follows easily from th
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https://en.wikipedia.org/wiki/Paris%20Kanellakis
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Paris Christos Kanellakis (; December 3, 1953 – December 20, 1995) was a Greek American computer scientist.
Life and academic path
Kanellakis was born on December 3, 1953, in Athens as the only child of General Eleftherios and Mrs. Argyroula Kanellakis.
In 1976, he received a diploma in electrical engineering from the National Technical University of Athens, with a thesis supervised by Emmanuel Protonotarios. He continued his studies at the graduate level in electrical engineering and computer science at the Massachusetts Institute of Technology. He received his M.Sc. degree in 1978. His thesis Algorithms for a scheduling application of the Asymmetric Traveling Salesman Problem was supervised by Ron Rivest and Michael Athans, although Christos Papadimitriou (then professor at Harvard) was also involved. He then continued working for his Ph.D. with Papadimitriou (who was then also at MIT) as advisor. He submitted his thesis The complexity of concurrency control for distributed databases in September 1981. He was awarded the doctorate degree in February 1982.
In 1981, he joined the Computer Science Department at Brown University as assistant professor. He obtained tenure as associate professor in 1986, and became full professor in 1990. He interrupted his stay at Brown in 1984 for a junior sabbatical as visiting assistant professor at the MIT Laboratory for Computer Science, working with Nancy Lynch, and in 1988 for a year at INRIA on special assignment leave, working with
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https://en.wikipedia.org/wiki/CWD
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CWD may refer to:
Biology
Cantabrian Water Dog, Spanish dog breed
Cell wall-deficient bacteria (or L forms)
Chronic wasting disease, of deer
Coarse woody debris, fallen trees and branches
Coffee wilt disease, in coffee trees
Common and well-documented, of human leukocyte antigen alleles
Train stations
Chatswood railway station, Sydney, Australia
Chawinda railway station, Punjab province, Pakistan
Creswell railway station, Derbyshire, England
Other uses
Canada's Worst Driver, a television series (2005–2018)
Clwyd, a preserved county of Wales (in genealogy)
Current working directory, in computing
Woods Cree language, spoken in Canada (ISO 639-3:cwd)
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https://en.wikipedia.org/wiki/Focused%20ion%20beam
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Focused ion beam, also known as FIB, is a technique used particularly in the semiconductor industry, materials science and increasingly in the biological field for site-specific analysis, deposition, and ablation of materials. A FIB setup is a scientific instrument that resembles a scanning electron microscope (SEM). However, while the SEM uses a focused beam of electrons to image the sample in the chamber, a FIB setup uses a focused beam of ions instead. FIB can also be incorporated in a system with both electron and ion beam columns, allowing the same feature to be investigated using either of the beams. FIB should not be confused with using a beam of focused ions for direct write lithography (such as in proton beam writing). These are generally quite different systems where the material is modified by other mechanisms.
Ion beam source
Most widespread instruments are using liquid metal ion sources (LMIS), especially gallium ion sources. Ion sources based on elemental gold and iridium are also available. In a gallium LMIS, gallium metal is placed in contact with a tungsten needle, and heated gallium wets the tungsten and flows to the tip of the needle, where the opposing forces of surface tension and electric field form the gallium into a cusp shaped tip called a Taylor cone. The tip radius of this cone is extremely small (~2 nm). The huge electric field at this small tip (greater than volts per centimeter) causes ionization and field emission of the gallium atoms.
Source
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https://en.wikipedia.org/wiki/Clifford%27s%20theorem%20on%20special%20divisors
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In mathematics, Clifford's theorem on special divisors is a result of on algebraic curves, showing the constraints on special linear systems on a curve C.
Statement
A divisor on a Riemann surface C is a formal sum of points P on C with integer coefficients. One considers a divisor as a set of constraints on meromorphic functions in the function field of C, defining as the vector space of functions having poles only at points of D with positive coefficient, at most as bad as the coefficient indicates, and having zeros at points of D with negative coefficient, with at least that multiplicity. The dimension of is finite, and denoted . The linear system of divisors attached to D is the corresponding projective space of dimension .
The other significant invariant of D is its degree d, which is the sum of all its coefficients.
A divisor is called special if ℓ(K − D) > 0, where K is the canonical divisor.
Clifford's theorem states that for an effective special divisor D, one has:
,
and that equality holds only if D is zero or a canonical divisor, or if C is a hyperelliptic curve and D linearly equivalent to an integral multiple of a hyperelliptic divisor.
The Clifford index of C is then defined as the minimum of taken over all special divisors (except canonical and trivial), and Clifford's theorem states this is non-negative. It can be shown that the Clifford index for a generic curve of genus g is equal to the floor function
The Clifford index measures how far the
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https://en.wikipedia.org/wiki/Metaplectic%20group
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In mathematics, the metaplectic group Mp2n is a double cover of the symplectic group Sp2n. It can be defined over either real or p-adic numbers. The construction covers more generally the case of an arbitrary local or finite field, and even the ring of adeles.
The metaplectic group has a particularly significant infinite-dimensional linear representation, the Weil representation. It was used by André Weil to give a representation-theoretic interpretation of theta functions, and is important in the theory of modular forms of half-integral weight and the theta correspondence.
Definition
The fundamental group of the symplectic Lie group Sp2n(R) is infinite cyclic, so it has a unique connected double cover, which is denoted Mp2n(R) and called the metaplectic group.
The metaplectic group Mp2(R) is not a matrix group: it has no faithful finite-dimensional representations. Therefore, the question of its explicit realization is nontrivial. It has faithful irreducible infinite-dimensional representations, such as the Weil representation described below.
It can be proved that if F is any local field other than C, then the symplectic group Sp2n(F) admits a unique perfect central extension with the kernel Z/2Z, the cyclic group of order 2, which is called the metaplectic group over F.
It serves as an algebraic replacement of the topological notion of a 2-fold cover used when . The approach through the notion of central extension is useful even in the case of real metaplectic group,
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https://en.wikipedia.org/wiki/Collision%20resistance
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In cryptography, collision resistance is a property of cryptographic hash functions: a hash function H is collision-resistant if it is hard to find two inputs that hash to the same output; that is, two inputs a and b where a ≠ b but H(a) = H(b). The pigeonhole principle means that any hash function with more inputs than outputs will necessarily have such collisions; the harder they are to find, the more cryptographically secure the hash function is.
The "birthday paradox" places an upper bound on collision resistance: if a hash function produces N bits of output, an attacker who computes only 2N/2 (or ) hash operations on random input is likely to find two matching outputs. If there is an easier method to do this than brute-force attack, it is typically considered a flaw in the hash function.
Cryptographic hash functions are usually designed to be collision resistant. However, many hash functions that were once thought to be collision resistant were later broken. MD5 and SHA-1 in particular both have published techniques more efficient than brute force for finding collisions. However, some hash functions have a proof that finding collisions is at least as difficult as some hard mathematical problem (such as integer factorization or discrete logarithm). Those functions are called provably secure.
Definition
A family of functions {hk : {0, 1}m(k) → {0, 1}l(k)} generated by some algorithm G is a family of collision-resistant hash functions, if |m(k)| > |l(k)| for any k, i.e.,
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https://en.wikipedia.org/wiki/Mohammed%20Naseeb%20Qureshy
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Mohammed Naseeb Qureshy (MN Qureshy) (4 January 1933 – 2005) was a prominent geologist from India.
His main field of study was Exploration geophysics. He graduated from Aligarh Muslim University (AMU) and earned his Dsc degree in Exploration geophysics from Colorado School of Mines.
During the early 1970s, MN Qureshy designed and coordinated the first indigenous aerial geophysical survey of the Western Ghats and Chitradurga Copper District in India. He also initiated the national regional gravity mapping programme which culminated in publication of first comprehensive gravity maps of India.
From 1983 to 1989, he served as the Advisor to the Government of India, Earth Sciences. During this time he helped establish some key Indian scientific organisations such as the National Remote Sensing Centre (NRSC), Hyderabad and the National Center for Medium Range Weather Forecasting (NCMRWF), New Delhi. He also initiated the Natural Resources Data Management System (NRDMS) to better serve national needs related to exploitation of natural resources. In 1989, Qureshy planned and established the Centre for Science and Technology of the Non-Aligned (NAM) and other Developing Countries.
Publications
1. MN Qureshy's research is synthesized in a book entitled Geophysical Framework of India, Bangladesh and Pakistan.
2. M. N QURESHY, N. KRISHNA BRAHMAM, S. C GARDE and B. K MATHUR, Gravity Anomalies and the Godavari Rift, India;
3. M. N. Qureshy and Waris E. K. Warsi, A Bouguer anomaly ma
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https://en.wikipedia.org/wiki/Viktor%20Meyer
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Viktor Meyer (8 September 18488 August 1897) was a German chemist and significant contributor to both organic and inorganic chemistry. He is best known for inventing an apparatus for determining vapour densities, the Viktor Meyer apparatus, and for discovering thiophene, a heterocyclic compound. He is sometimes referred to as Victor Meyer, a name used in some of his publications.
Early life
Viktor Meyer was born in Berlin in 1848, the son of trader and cotton printer Jacques Meyer and mother, Bertha. His parents were Jewish, though he was not actively raised in the Jewish faith. Later, he was confirmed in a Reform Jewish congregation. He married a Christian woman, Hedwig Davidson, and raised his children as such. He entered the gymnasium at the age of ten in the same class as his two-year older brother Richard. Although he had excellent science skills his wish to become an actor was based on his love for poetry. At a visit from his brother Richard, who was studying chemistry at the University of Heidelberg, he became attracted to chemistry.
In 1865, when not yet 17 years old but pushed by his parents, Meyer began studying chemistry at the University of Berlin, the same year that August Wilhelm von Hofmann succeeded Eilhard Mitscherlich as the Chair of Chemistry there. After one semester, Meyer went to Heidelberg to work under Robert Bunsen, where he also heard lectures on organic chemistry by Emil Erlenmeyer. As no research was required under Bunsen at the time, Meyer recei
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https://en.wikipedia.org/wiki/Emit%20Bloch
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David Edmund Turin (born 8 September 1965), known as Emit Bloch, is an American songwriter and musician.
Background
Emit Bloch is a singer, songwriter and musician referenced for field recordings and lo-fi music production. His parents are George L. Turin, a professor of Electrical Engineering and Computer Sciences at UC Berkeley, and Helen Elizabeth Turin, the daughter of a Utah cattle rancher. Bloch was raised in Berkeley, California, as well as Layton, Utah, and is related to Christopher Layton, a prominent 19th Century Mormon pioneer.
Career
Bloch has issued several notable collections, with his 2010 release Dictaphones Vol. 1 garnering 5/5 stars in UNCUT, the magazine calling Bloch an "exceptional songwriter" and the release "utterly remarkable", as well as frequent radio play on BBC stations when it was issued on One Little Independent records. London's The Sun called the record "...fresh, vital, uncluttered and brilliant" and awarded it 4.5/5 stars.
The subsequent digital EP, "Dorothy," included some studio versions of songs on Dictaphones Vol. 1 and received UK-wide acclaim when it was selected by The London Times as "Hot Download of the Week" and its eponymous single was championed by Dermot O'Leary, Gideon Coe and several other mainstream BBC DJs.
In 2000, Bloch wrote and recorded the occult Milla Jovovich, The People Tree Sessions, for his internet imprint Peopletree, an early example of internet marketing. The largely field recorded release was chosen as th
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https://en.wikipedia.org/wiki/Bred%20vector
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In applied mathematics, bred vectors are perturbations related to Lyapunov vectors, that capture fast-growing dynamical instabilities of the solution of a numerical model. They are used, for example, as initial perturbations for ensemble forecasting in numerical weather prediction. They were introduced by Zoltan Toth and Eugenia Kalnay.
Method
Bred vectors are created by adding initially random perturbations to a nonlinear model. The control (unperturbed) and the perturbed models are integrated in time, and periodically the control solution is subtracted from the perturbed solution. This difference is the bred vector. The vector is scaled to be the same size as the initial perturbation and is then added back to the control to create the new perturbed initial condition. After a short transient period, this "breeding" process creates bred vectors dominated by the naturally fastest-growing instabilities of the evolving control solution.
References
Functional analysis
Mathematical physics
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https://en.wikipedia.org/wiki/Plimpton%20322
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Plimpton 322 is a Babylonian clay tablet, notable as containing an example of Babylonian mathematics. It has number 322 in the G.A. Plimpton Collection at Columbia University. This tablet, believed to have been written about 1800 BC, has a table of four columns and 15 rows of numbers in the cuneiform script of the period.
This table lists two of the three numbers in what are now called Pythagorean triples, i.e., integers , , and satisfying . From a modern perspective, a method for constructing such triples is a significant early achievement, known long before the Greek and Indian mathematicians discovered solutions to this problem. At the same time, one should recall the tablet's author was a scribe, rather than a professional mathematician; it has been suggested that one of his goals may have been to produce examples for school problems.
There has been significant scholarly debate on the nature and purpose of the tablet. For readable popular treatments of this tablet see recipient of the Lester R. Ford Award for expository excellence in mathematics or, more briefly, . is a more detailed and technical discussion of the interpretation of the tablet's numbers, with an extensive bibliography.
Provenance and dating
Plimpton 322 is partly broken, approximately 13 cm wide, 9 cm tall, and 2 cm thick. New York publisher George Arthur Plimpton purchased the tablet from an archaeological dealer, Edgar J. Banks, in about 1922, and bequeathed it with the rest of his collection t
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https://en.wikipedia.org/wiki/251%20%28number%29
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251 (two hundred [and] fifty-one) is the natural number between 250 and 252. It is also a prime number.
In mathematics
251 is:
a Sophie Germain prime.
the sum of three consecutive primes (79 + 83 + 89) and seven consecutive primes (23 + 29 + 31 + 37 + 41 + 43 + 47).
a Chen prime.
an Eisenstein prime with no imaginary part.
a de Polignac number, meaning that it is odd and cannot be formed by adding a power of two to a prime number.
the smallest number that can be formed in more than one way by summing three positive cubes:
Every 5 × 5 matrix has exactly 251 square submatrices.
References
Integers
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https://en.wikipedia.org/wiki/Schweitzer%20Engineering%20Laboratories
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Schweitzer Engineering Laboratories, Inc. (SEL) designs, manufactures, and supports products and services ranging from generator and transmission protection to distribution automation and control systems. Founded in 1982 by Edmund O. Schweitzer III, SEL shipped the world's first digital protective relay. Presently, the company designs and manufactures embedded system products for protecting, monitoring, control, and metering of electric power systems.
The company serves a variety of industries, including utilities, pulp and paper, transportation, water and wastewater, education, healthcare, government, mission-critical facilities, and oil, gas, and petrochemical operations.
SEL is 100 percent employee owned, headquartered in Pullman, Washington, with about 2,300 based there in addition to 2,700 employees in field offices and other manufacturing facilities in about 60 national locations, in addition to another 50 international.
History
SEL was founded in Pullman, Washington in 1982 when Dr. Edmund O. Schweitzer III invented and marketed the first all-digital protective relay.
Schweitzer created the relay as a Ph.D. project while at Washington State University. He sold his first product, the SEL-21, to Otter Tail Power Company in Fergus Falls, Minnesota in 1984. Otter Tail initially used the SEL-21 for its fault location and event recording functions.
In 1985, SEL built its first building and employed eleven people. In 2009, SEL became 100% employee-owned under an employe
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https://en.wikipedia.org/wiki/Edmund%20O.%20Schweitzer%20III
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Edmund O. Schweitzer III (born 1947, Evanston, Illinois) is an electrical engineer, inventor, and founder of Schweitzer Engineering Laboratories (SEL). Schweitzer launched SEL in 1982 in Pullman, Washington. Today, SEL manufacturers a wide variety of products that protect the electric power grid and industrial control systems at its five state-of-the-art U.S. manufacturing facilities in Pullman, Washington; Lewiston, Idaho; Lake Zurich, Illinois; West Lafayette, Indiana, and; Moscow, Idaho. SEL products and technologies are used in virtually every substation in North America and are in operation in 164 countries.
Recognized as a pioneer in digital protection, Schweitzer has been credited with “revolutionizing the performance of electric power systems with computer-based protection and control equipment, and making a major impact in the electric power utility industry.”
Early life and education
Schweitzer obtained a B.S. (’68) and M.S. (’71) from Purdue University and a Ph.D. (’77) from Washington State University.
He comes from a family of inventors. His grandfather, Edmund Oscar Schweitzer, earned 87 patents. He invented the first reliable high-voltage fuse in collaboration with Nicholas John Conrad in 1911, the same year the two founded Schweitzer and Conrad, Inc., today known as S&C Electric Company. His father, Edmund O. Schweitzer, Jr., earned 208 patents. He invented several different line-powered fault indicating devices and founded E.O. Schweitzer Manufacturing Co
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https://en.wikipedia.org/wiki/Weyl%27s%20theorem
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In mathematics, Weyl's theorem or Weyl's lemma might refer to one of a number of results of Hermann Weyl. These include
the Peter–Weyl theorem
Weyl's theorem on complete reducibility, results originally derived from the unitarian trick on representation theory of semisimple groups and semisimple Lie algebras
Weyl's theorem on eigenvalues
Weyl's criterion for equidistribution (Weyl's criterion)
Weyl's lemma on the hypoellipticity of the Laplace equation
results estimating Weyl sums in the theory of exponential sums
Weyl's inequality
Weyl's criterion for a number to be in the essential spectrum of an operator
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https://en.wikipedia.org/wiki/GlueX
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GlueX is a particle physics experiment located at the Thomas Jefferson National Accelerator Facility (JLab) accelerator in Newport News, Virginia. Its primary purpose is to better understand the nature of confinement in quantum chromodynamics (QCD) by identifying a spectrum of hybrid and exotic mesons generated by the excitation of the gluonic field binding the quarks. Such mesonic states are predicted to exist outside of the well-established quark model, but none have been definitively identified by previous experiments. A broad high-statistics survey of known light mesons up to and including the is also underway.
Experimental Apparatus
The experiment uses photoproduction (that is, the scattering of a real photon on a nucleon) to produce mesonic states. Unlike previous similar experiments, it uses linearly polarized photons, which allows the analysis of accumulated events for certain polarization observables that are thought to make identification of exotic states feasible.
The GlueX detector was installed in the new Hall D (the fourth such hall at JLab) as part of the accelerator's upgrade to 12 GeV energy. GlueX began its first commissioning run in 2014, and first received 12 GeV electrons in 2015, the highest energy available at the CEBAF accelerator. Publication-quality physics data was accumulated during multi-weeks runs starting in 2016, continuing into 2023 and beyond.
The detector is based on a solenoidal hermetic detector optimized for tracking of charge
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https://en.wikipedia.org/wiki/Square-free%20element
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In mathematics, a square-free element is an element r of a unique factorization domain R that is not divisible by a non-trivial square. This means that every s such that is a unit of R.
Alternate characterizations
Square-free elements may be also characterized using their prime decomposition. The unique factorization property means that a non-zero non-unit r can be represented as a product of prime elements
Then r is square-free if and only if the primes pi are pairwise non-associated (i.e. that it doesn't have two of the same prime as factors, which would make it divisible by a square number).
Examples
Common examples of square-free elements include square-free integers and square-free polynomials.
See also
Prime number
References
David Darling (2004) The Universal Book of Mathematics: From Abracadabra to Zeno's Paradoxes John Wiley & Sons
Baker, R. C. "The square-free divisor problem." The Quarterly Journal of Mathematics 45.3 (1994): 269-277.
Ring theory
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https://en.wikipedia.org/wiki/Signed%20measure
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In mathematics, signed measure is a generalization of the concept of (positive) measure by allowing the set function to take negative values, i.e., to acquire sign.
Definition
There are two slightly different concepts of a signed measure, depending on whether or not one allows it to take infinite values. Signed measures are usually only allowed to take finite real values, while some textbooks allow them to take infinite values. To avoid confusion, this article will call these two cases "finite signed measures" and "extended signed measures".
Given a measurable space (that is, a set with a σ-algebra on it), an extended signed measure is a set function
such that and is σ-additive – that is, it satisfies the equality
for any sequence of disjoint sets in
The series on the right must converge absolutely when the value of the left-hand side is finite. One consequence is that an extended signed measure can take or as a value, but not both. The expression is undefined and must be avoided.
A finite signed measure (a.k.a. real measure) is defined in the same way, except that it is only allowed to take real values. That is, it cannot take or
Finite signed measures form a real vector space, while extended signed measures do not because they are not closed under addition. On the other hand, measures are extended signed measures, but are not in general finite signed measures.
Examples
Consider a non-negative measure on the space (X, Σ) and a measurable function f: X →
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https://en.wikipedia.org/wiki/Hahn%20decomposition%20theorem
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In mathematics, the Hahn decomposition theorem, named after the Austrian mathematician Hans Hahn, states that for any measurable space and any signed measure defined on the -algebra , there exist two -measurable sets, and , of such that:
and .
For every such that , one has , i.e., is a positive set for .
For every such that , one has , i.e., is a negative set for .
Moreover, this decomposition is essentially unique, meaning that for any other pair of -measurable subsets of fulfilling the three conditions above, the symmetric differences and are -null sets in the strong sense that every -measurable subset of them has zero measure. The pair is then called a Hahn decomposition of the signed measure .
Jordan measure decomposition
A consequence of the Hahn decomposition theorem is the , which states that every signed measure defined on has a unique decomposition into a difference of two positive measures, and , at least one of which is finite, such that for every -measurable subset and for every -measurable subset , for any Hahn decomposition of . We call and the positive and negative part of , respectively. The pair is called a Jordan decomposition (or sometimes Hahn–Jordan decomposition) of . The two measures can be defined as
for every and any Hahn decomposition of .
Note that the Jordan decomposition is unique, while the Hahn decomposition is only essentially unique.
The Jordan decomposition has the following corollary: Given a Jordan dec
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https://en.wikipedia.org/wiki/Character%20sum
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In mathematics, a character sum is a sum of values of a Dirichlet character χ modulo N, taken over a given range of values of n. Such sums are basic in a number of questions, for example in the distribution of quadratic residues, and in particular in the classical question of finding an upper bound for the least quadratic non-residue modulo N. Character sums are often closely linked to exponential sums by the Gauss sums (this is like a finite Mellin transform).
Assume χ is a non-principal Dirichlet character to the modulus N.
Sums over ranges
The sum taken over all residue classes mod N is then zero. This means that the cases of interest will be sums over relatively short ranges, of length R < N say,
A fundamental improvement on the trivial estimate is the Pólya–Vinogradov inequality, established independently by George Pólya and I. M. Vinogradov in 1918, stating in big O notation that
Assuming the generalized Riemann hypothesis, Hugh Montgomery and R. C. Vaughan have shown that there is the further improvement
Summing polynomials
Another significant type of character sum is that formed by
for some function F, generally a polynomial. A classical result is the case of a quadratic, for example,
and χ a Legendre symbol. Here the sum can be evaluated (as −1), a result that is connected to the local zeta-function of a conic section.
More generally, such sums for the Jacobi symbol relate to local zeta-functions of elliptic curves and hyperelliptic curves; this means tha
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https://en.wikipedia.org/wiki/Kodaira%20embedding%20theorem
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In mathematics, the Kodaira embedding theorem characterises non-singular projective varieties, over the complex numbers, amongst compact Kähler manifolds. In effect it says precisely which complex manifolds are defined by homogeneous polynomials.
Kunihiko Kodaira's result is that for a compact Kähler manifold M, with a Hodge metric, meaning that the cohomology class in degree 2 defined by the Kähler form ω is an integral cohomology class, there is a complex-analytic embedding of M into complex projective space of some high enough dimension N.
The fact that M embeds as an algebraic variety follows from its compactness by Chow's theorem.
A Kähler manifold with a Hodge metric is occasionally called a Hodge manifold (named after W. V. D. Hodge), so Kodaira's results states that Hodge manifolds are projective.
The converse that projective manifolds are Hodge manifolds is more elementary and was already known.
Kodaira also proved (Kodaira 1963), by recourse to the classification of compact complex surfaces, that every compact Kähler surface is a deformation of a projective Kähler surface. This was later simplified by Buchdahl to remove reliance on the classification (Buchdahl 2008).
Kodaira embedding theorem
Let X be a compact Kähler manifold, and L a holomorphic line bundle on X. Then L is a positive line bundle if and only if there is a holomorphic embedding of X into some projective space such that for some m > 0.
See also
Fujita conjecture
Hodge structure
Moishezon
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https://en.wikipedia.org/wiki/Schr%C3%B6dinger%27s%20cat%20in%20popular%20culture
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Schrödinger's cat is a thought experiment, usually described as a paradox, devised by Austrian physicist Erwin Schrödinger in 1935. It illustrates what he saw as absurdities in the views that other physicists had about quantum mechanics (ideas later labeled the Copenhagen interpretation), by applying them not to microscopic objects but to everyday ones. The thought experiment presents a cat that might be alive or dead, depending on an earlier random event. In the course of developing this experiment, he coined the term Verschränkung (entanglement). It was not long before science-fiction writers picked up this evocative concept, often using it in a humorous vein. Works of fiction have employed Schrödinger's thought experiment as plot device and as metaphor, in genres from apocalyptic science fiction to young-adult drama, making the cat more prominent in popular culture than in physics itself.
Schrödinger's cat has been a motive in many science fiction works, and used as a title of a number of them, including Greg Bear's "Schrödinger's Plague" (Analog, 29 March 1982), George Alec Effinger's "Schrödinger's Kitten" (Omni, September 1988), Ursula Le Guin's "Schrödinger's Cat" (in the 1974 anthology Universe 5), F. Gwynplaine MacIntyre's "Schrödinger's Cat-Sitter" (Analog, July/August 2001), Rudy Rucker's "Schrödinger's Cat" (Analog, 30 March 1981), and Robert Anton Wilson's Schrödinger's Cat Trilogy (1988), illustrating various interpretations of quantum physics. In addition to n
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https://en.wikipedia.org/wiki/Product%20measure
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In mathematics, given two measurable spaces and measures on them, one can obtain a product measurable space and a product measure on that space. Conceptually, this is similar to defining the Cartesian product of sets and the product topology of two topological spaces, except that there can be many natural choices for the product measure.
Let and be two measurable spaces, that is, and are sigma algebras on and respectively, and let and be measures on these spaces. Denote by the sigma algebra on the Cartesian product generated by subsets of the form , where and This sigma algebra is called the tensor-product σ-algebra on the product space.
A product measure
(also denoted by by many authors)
is defined to be a measure on the measurable space satisfying the property
for all
.
(In multiplying measures, some of which are infinite, we define the product to be zero if any factor is zero.)
In fact, when the spaces are -finite, the product measure is uniquely defined, and for every measurable set E,
where and , which are both measurable sets.
The existence of this measure is guaranteed by the Hahn–Kolmogorov theorem. The uniqueness of product measure is guaranteed only in the case that both and are σ-finite.
The Borel measures on the Euclidean space Rn can be obtained as the product of n copies of Borel measures on the real line R.
Even if the two factors of the product space are complete measure spaces, the product space may not be. Consequently,
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https://en.wikipedia.org/wiki/Actor%20modeling
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In computer science, Actor modeling is a form of software modeling which focuses on software actors. Actor modeling is most prominently used for the early modeling of requirements; through this it becomes possible to understand who the users and stakeholders of a system are and what their interests and needs are regarding that system. The increasing complexity of today's systems makes it more appropriate to take this approach, instead of a traditional, more mechanically focused approach. When thinking along the dimensions of users and their needs, it is easier to comprehend what the system is designed to accomplish. This approach furthermore helps the users to define the requirements for the system.
The approach of actor modeling is normally combined with the modeling of goals and tasks to give a better understanding of the situation the user is in. There are different modeling languages that support actor modeling; examples include i* and EEML.
The Actor
The central entity of the Actor modeling – the actor itself – can be any kind of entity that is performing action(s). It may for example be a person, a department, or an organization. The goal of actor modeling is to understand the actor better. To do so, it is important to understand the actor, who he is and why he does what he does.
The actor has attributes that define it:
The actor has goals, skills and responsibilities.
The actor performs tasks with a certain purpose in mind.
The actor depends on other actors, resour
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https://en.wikipedia.org/wiki/Ross%20Freeman
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Ross Freeman (July 26, 1948 – October 22, 1989), was an American electrical engineer and inventor, and co-founder of the leading FPGA developer Xilinx.
Early life and education
Freeman was born in the upper peninsula of Michigan on July 26, 1948. He grew up on a farm near Engadine, Michigan.
Freeman earned a BS degree in physics from Michigan State University in 1969 and a master’s from University of Illinois in 1971. He worked in the Peace Corps for several years, then went to Teletype Corporation to design a custom PMOS circuit.
Founding of Xilinx
Ross postulated that because of Moore's Law, transistors would be getting less expensive each year, making customizable programmable chips affordable. The idea was "far out" at the time, but the company and technology grew quickly, eventually catching the attention of new-found competitors in what is now a mature industry.
With Bernard Vonderschmitt and James V Barnett II Freeman co-founded Xilinx in 1984, and a year later invented the first field-programmable gate array (FPGA). Freeman's invention - patent 4,870,302 - is a computer chip full of 'open gates' that engineers can reprogram as much as needed to add new functionality, adapt to changing standards or specifications and make last minute design changes.
Death and legacy
Freeman died in 1989, only a few years after creating a new industry with the FPGA and launching what would become a multi-billion dollar company.
In 2006, 17 years after his death, Freeman was
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https://en.wikipedia.org/wiki/Axillary
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Axillary means "related to the axilla (armpit)" or "related to the leaf axils".
"Axillary" may refer to:
Biology
Axillary artery
Axillary border
Axillary fascia
Axillary feathers
Axillary hairs
Axillary lines
Axillary lymph nodes
Axillary nerve
Axillary process
Axillary sheath
Axillary space
Axillary tail
Axillary vein
Axillary (botany), of a flower or other structure found in a leaf axil
See also
Auxiliary (disambiguation)
Maxillary (disambiguation)
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https://en.wikipedia.org/wiki/Salt%20bridge%20%28protein%20and%20supramolecular%29
|
In chemistry, a salt bridge is a combination of two non-covalent interactions: hydrogen bonding and ionic bonding (Figure 1). Ion pairing is one of the most important noncovalent forces in chemistry, in biological systems, in different materials and in many applications such as ion pair chromatography. It is a most commonly observed contribution to the stability to the entropically unfavorable folded conformation of proteins. Although non-covalent interactions are known to be relatively weak interactions, small stabilizing interactions can add up to make an important contribution to the overall stability of a conformer. Not only are salt bridges found in proteins, but they can also be found in supramolecular chemistry. The thermodynamics of each are explored through experimental procedures to access the free energy contribution of the salt bridge to the overall free energy of the state.
Salt bridges in chemical bonding
In water, formation of salt bridges or ion pairs is mostly driven by entropy, usually accompanied by unfavorable ΔH contributions on account of desolvation of the interacting ions upon association. Hydrogen bonds contribute to the stability of ion pairs with e.g. protonated ammonium ions, and with anions is formed by deprotonation as in the case of carboxylate, phosphate etc; then the association constants depend on the pH. Entropic driving forces for ion pairing (in absence of significant H-bonding contributions) are also found in methanol as solvent. In
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https://en.wikipedia.org/wiki/TRIX%20%28operating%20system%29
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TRIX is a network-oriented research operating system developed in the late 1970s at MIT's Laboratory for Computer Science (LCS) by Professor Steve Ward and his research group. It ran on the NuMachine and had remote procedure call functionality built into its kernel, but was otherwise a Version 7 Unix workalike.
Design and implementation
On startup, the NuMachine would load the same program on each CPU in the system, passing each instance the numeric ID of the CPU it was running on. TRIX relied on this design to have the first CPU set up global data structures and then set a flag to signal that initialization was complete. After that, each instance of the kernel was able to access global data. The system also supported data private to each CPU. Access to the filesystem was provided by a program in user space.
The kernel supported unnamed threads running in domains. A domain was the equivalent of a Unix process without a stack pointer (each thread in a domain had a stack pointer). A thread could change domains, and the system scheduler would migrate threads between CPUs in order to keep all processors busy. Threads had access to a single kind of mutual exclusion primitive, and one of seven priorities. The scheduler was designed to avoid priority inversion. User space programs could create threads through a spawn system call.
A garbage collector would periodically identify and free unused domains.
The shared memory model used to coordinate work between the various CP
|
https://en.wikipedia.org/wiki/Huntington%20Willard
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Huntington Faxon Willard (born c.1953) is an American geneticist. In 2014, he was named to head the Marine Biological Laboratory, and is a professor in human genetics at the University of Chicago. He stepped down from leading the lab in 2017 to return to research. Willard was elected to the National Academy of Medicine in 2016. Earlier, beginning in 2003 he was the Nanaline H. Duke Professor of Genome Sciences, the first director of the Institute for Genome Sciences and Policy, and Vice Chancellor for Genome Sciences at Duke University Medical Center in Durham, North Carolina.
Willard graduated from the Belmont Hill School in Belmont, Massachusetts in 1971. He received his A.B. degree in biology from Harvard University in 1975 and his Ph.D. from Yale University in 1979. He did a postdoctoral fellowship in medical genetics at Johns Hopkins University from 1979-81.
He then held positions at the University of Toronto from 1982 to 1989, Stanford University from 1989 to 1992, and was Chairman of the Department of Genetics at Case Western Reserve University from 1992 to 2002.
His current research interests include genome sciences and their broad implications for medicine and society, human chromosome structure and function, X-inactivation and mechanisms of gene silencing, and the first reported development of human artificial chromosomes for studies of gene transfer and functional genomics. Studies of the X-chromosome in his laboratory by Carolyn J. Brown led to the discovery
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https://en.wikipedia.org/wiki/Kodaira%20vanishing%20theorem
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In mathematics, the Kodaira vanishing theorem is a basic result of complex manifold theory and complex algebraic geometry, describing general conditions under which sheaf cohomology groups with indices q > 0 are automatically zero. The implications for the group with index q = 0 is usually that its dimension — the number of independent global sections — coincides with a holomorphic Euler characteristic that can be computed using the Hirzebruch–Riemann–Roch theorem.
The complex analytic case
The statement of Kunihiko Kodaira's result is that if M is a compact Kähler manifold of complex dimension n, L any holomorphic line bundle on M that is positive, and KM is the canonical line bundle, then
for q > 0. Here stands for the tensor product of line bundles. By means of Serre duality, one also obtains the vanishing of for q < n. There is a generalisation, the Kodaira–Nakano vanishing theorem, in which , where Ωn(L) denotes the sheaf of holomorphic (n,0)-forms on M with values on L, is replaced by Ωr(L), the sheaf of holomorphic (r,0)-forms with values on L. Then the cohomology group Hq(M, Ωr(L)) vanishes whenever q + r > n.
The algebraic case
The Kodaira vanishing theorem can be formulated within the language of algebraic geometry without any reference to transcendental methods such as Kähler metrics. Positivity of the line bundle L translates into the corresponding invertible sheaf being ample (i.e., some tensor power gives a projective embedding). The algebraic Kodaira–Ak
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https://en.wikipedia.org/wiki/Tarek%20Kamel
|
Tarek Kamel (8 May 1962 – 10 October 2019) was an Egyptian politician and computer engineer expert in global Internet governance issues.
Early life and education
Tarek Kamel was born in Cairo, Egypt on 8 May 1962. He graduated from Cairo University with a B.Sc. in electrical engineering and then received an M.Sc. in electrical engineering from the same school. From 1989 to 1992 he pursued his Ph.D. in electrical engineering and information technology at the Technical University of Munich with the support of the German Academic Exchange Service (DAAD).
Career
Kamel started his career as a network support engineer for the Academy of Scientific Research and Technology, then an assistant researcher at the Electronics Research Institute. Returning to Egypt from Germany, he became manager of the Communications and Networking Department at the Cabinet Information and Decision Support Centre (IDSC/RITSEC), and gained a professorship at the ERI. It is during this period (from 1992 to 1999) that he established Egypt's first connection to the Internet, steered the introduction of commercial Internet services in Egypt and founded the Internet Society of Egypt. Kamel joined the ministry of communications and information technology since its formation in October 1999, where he had been appointed senior advisor to the minister following his pioneering efforts in ICT. He was board member of Telecom Egypt from 2000 to 2004 and a board member of Egypt’s Private Public Technology Development
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https://en.wikipedia.org/wiki/Matrass
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A matrass (mod. Latin matracium) is a glass vessel with a round or oval body and a long narrow neck, used in chemistry as a digester or distiller. The Florence flask of commerce is frequently used for this purpose. The word is possibly identical with an old name matrass (Fr. materas, matelas) for the bolt or quarrel of a cross-bow. If so, some identity of shape is the reason for the application of the word; bolthead is also used as a name for the vessel. Another connection is suggested with the Arabic matra, a leather bottle.
References
See also
Laboratory flask
External links
Laboratory equipment
es:Matraz
it:Matraccio
|
https://en.wikipedia.org/wiki/Church%20encoding
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In mathematics, Church encoding is a means of representing data and operators in the lambda calculus. The Church numerals are a representation of the natural numbers using lambda notation. The method is named for Alonzo Church, who first encoded data in the lambda calculus this way.
Terms that are usually considered primitive in other notations (such as integers, booleans, pairs, lists, and tagged unions) are mapped to higher-order functions under Church encoding. The Church–Turing thesis asserts that any computable operator (and its operands) can be represented under Church encoding. In the untyped lambda calculus the only primitive data type is the function.
Use
A straightforward implementation of Church encoding slows some access operations from to , where is the size of the data structure, making Church encoding impractical. Research has shown that this can be addressed by targeted optimizations, but most functional programming languages instead expand their intermediate representations to contain algebraic data types. Nonetheless Church encoding is often used in theoretical arguments, as it is a natural representation for partial evaluation and theorem proving. Operations can be typed using higher-ranked types, and primitive recursion is easily accessible. The assumption that functions are the only primitive data types streamlines many proofs.
Church encoding is complete but only representationally. Additional functions are needed to translate the representation
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https://en.wikipedia.org/wiki/Secure%20environment
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In computing, a secure environment is any system which implements the controlled storage and use of information. In the event of computing data loss, a secure environment is used to protect personal or confidential data.
Often, secure environments employ cryptography as a means to protect information.
Some secure environments employ cryptographic hashing, simply to verify that the information has not been altered since it was last modified.
See also
Data recovery
Cleanroom
Mandatory access control (MAC)
Trusted computing
Homomorphic encryption
Computer security
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https://en.wikipedia.org/wiki/Thomas%20Taylor%20%28historian%29
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Thomas Taylor (26 February 1858 – 5 July 1938) was an English priest, historian and scholar of Celtic culture.
Life and career
Taylor was born in Thurvaston, Derbyshire, England. He attended King Edward VI School, Macclesfield becoming head boy in 1874. He matriculated at St Catharine's College, Cambridge in 1877, and graduated in the Mathematics Tripos in 1881, receiving his MA in 1886. Taylor took Holy Orders on going down from Cambridge, being ordained Deacon at Rochester in 1881 and was made Priest there in 1883.
After a few years (1883 – c. 1896) in Queensland, Australia, he settled with his wife and family in Cornwall. He served as Vicar first at All Saints' Church, Falmouth, from 1890 and then at Redruth from 1892. In 1897 he accepted the rural living of St Breward. In 1900 he became the Vicar of St Just in Penwith.
Taylor was an honorary Canon of Truro Cathedral from 1917 to 1938. In 1919 he went to serve at Gunwalloe. He was elected Proctor and held this office from 1919 to 1935. He also served as Rural Dean of Penwith from 1924 to 1927. He became known as "the poor man’s lawyer" as a result of his freely given assistance in matters of compensation for injuries sustained in tin mining.
Canon Taylor was made a bard at the inaugural Gorseth Kernow held at Boscawen-Un, St Buryan on 21 September 1928. He took the bardic name ‘'Gwas Ust'’ (‘Servant of St. Just’).
When he died in 1938, he was Vicar of St. Just. He listed his recreations as pedigree making and fly fis
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https://en.wikipedia.org/wiki/Key%20whitening
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In cryptography, key whitening is a technique intended to increase the security of an iterated block cipher. It consists of steps that combine the data with portions of the key.
Details
The most common form of key whitening is xor-encrypt-xor -- using a simple XOR before the first round and after the last round of encryption.
The first block cipher to use a form of key whitening is DES-X, which simply uses two extra 64-bit keys for whitening, beyond the normal 56-bit key of DES. This is intended to increase the complexity of a brute force attack, increasing the effective size of the key without major changes in the algorithm. DES-X's inventor, Ron Rivest, named the technique whitening.
The cipher FEAL (followed by Khufu and Khafre) introduced the practice of key whitening using portions of the same key used in the rest of the cipher. This offers no additional protection from brute force attacks, but it can make other attacks more difficult. In a Feistel cipher or similar algorithm, key whitening can increase security by concealing the specific inputs to the first and last round functions. In particular, it is not susceptible to a meet-in-the-middle attack. This form of key whitening has been adopted as a feature of many later block ciphers, including AES, MARS, RC6, and Twofish.
See also
Whitening transformation
References
Key management
Block ciphers
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https://en.wikipedia.org/wiki/Hodgkin%E2%80%93Huxley%20model
|
The Hodgkin–Huxley model, or conductance-based model, is a mathematical model that describes how action potentials in neurons are initiated and propagated. It is a set of nonlinear differential equations that approximates the electrical engineering characteristics of excitable cells such as neurons and muscle cells. It is a continuous-time dynamical system.
Alan Hodgkin and Andrew Huxley described the model in 1952 to explain the ionic mechanisms underlying the initiation and propagation of action potentials in the squid giant axon. They received the 1963 Nobel Prize in Physiology or Medicine for this work.
Basic components
The typical Hodgkin–Huxley model treats each component of an excitable cell as an electrical element (as shown in the figure). The lipid bilayer is represented as a capacitance (Cm). Voltage-gated ion channels are represented by electrical conductances (gn, where n is the specific ion channel) that depend on both voltage and time. Leak channels are represented by linear conductances (gL). The electrochemical gradients driving the flow of ions are represented by voltage sources (En) whose voltages are determined by the ratio of the intra- and extracellular concentrations of the ionic species of interest. Finally, ion pumps are represented by current sources (Ip). The membrane potential is denoted by Vm.
Mathematically, the current flowing through the lipid bilayer is written as
and the current through a given ion channel is the product of that chan
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https://en.wikipedia.org/wiki/Cigarette%20smokers%20problem
|
The cigarette smokers problem is a concurrency problem in computer science, originally described in 1971 by Suhas Patil. The problem has been criticized for having "restrictions which cannot be justified by practical considerations."
Problem description
Patil's problem includes a "quite arbitrary" "restriction that the process which supplies the ingredients cannot be changed and that no conditional statements may be used."
Assume a cigarette requires three ingredients to make and smoke: tobacco, paper, and matches. There are three smokers around a table, each of whom has an infinite supply of one of the three ingredients — one smoker has an infinite supply of tobacco, another has paper, and the third has matches.
There is also a non-smoking agent who enables the smokers to make their cigarettes by arbitrarily (non-deterministically) selecting two of the supplies to place on the table. The smoker who has the third supply should remove the two items from the table, using them (along with their own supply) to make a cigarette, which they smoke for a while. Once the smoker has finished his cigarette, the agent places two new random items on the table. This process continues forever.
Three semaphores are used to represent the items on the table; the agent increases the appropriate semaphore to signal that an item has been placed on the table, and smokers decrement the semaphore when removing items. Also, each smoker has an associated semaphore that they use to signal to the a
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https://en.wikipedia.org/wiki/263%20%28number%29
|
263 is the natural number between 262 and 264. It is also a prime number.
In mathematics
263 is
a balanced prime,
an irregular prime,
a Ramanujan prime, a Chen prime, and
a safe prime.
It is also a strictly non-palindromic number and a happy number.
References
Integers
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https://en.wikipedia.org/wiki/269%20%28number%29
|
269 (two hundred [and] sixty-nine) is the natural number between 268 and 270. It is also a prime number.
In mathematics
269 is a twin prime,
and a Ramanujan prime.
It is the largest prime factor of 9! + 1 = 362881,
and the smallest natural number that cannot be represented as the determinant of a 10 × 10 (0,1)-matrix.
References
Integers
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