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https://en.wikipedia.org/wiki/Selmer%20Bringsjord
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Selmer Bringsjord (born November 24, 1958) is the chair of the Department of Cognitive Science at Rensselaer Polytechnic Institute and a professor of Computer Science and Cognitive Science. He also holds an appointment in the Lally School of Management & Technology and teaches artificial Intelligence (AI), formal logic, human and machine reasoning, and philosophy of AI.
Bringsjord's education includes a B.A. in Philosophy from the University of Pennsylvania and a Ph.D. in Philosophy from Brown University. He conducts research in AI as the director of the Rensselaer AI & Reasoning Laboratory (RAIR). He specializes in the logico-mathematical and philosophical foundations of AI and cognitive science, and in collaboratively building AI systems on the basis of computational logic.
Bringsjord believes that "the human mind will forever be superior to AI", and that "much of what many humans do for a living will be better done by indefatigable machines who require not a cent in pay". Bringsjord has stated that the "ultimate growth industry will be building smarter and smarter such machines on the one hand, and philosophizing about whether they are truly conscious and free on the other".
Bringsjord has an argument for P = NP using digital physics. Other research includes developing a new computational-logic framework allowing the formalization of deliberative multi-agent "mindreading" as applied to the realm of nuclear strategy, with the goal of creating a model and simulation to en
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https://en.wikipedia.org/wiki/Martin%20Nowak
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Martin Andreas Nowak (born April 7, 1965) is an Austrian-born professor of mathematics and biology at Harvard University. He is one of the leading researchers in the field of mathematical biology. He made contributions to the theory of evolution, cooperation, virus dynamics, and cancer dynamics. Nowak held professorships at Oxford University and at the Institute for Advanced Study, Princeton, before being recruited by Harvard in 2003. He was the director of Harvard's program for evolutionary dynamics from 2003 until 2020. He is a professor in the Department of Mathematics and in the Department of Organismic and Evolutionary Biology.
Nowak has authored more than 500 academic papers and has been cited more than 140,000 times. In addition, Nowak has authored four books, who have received critical praise. Nowak's best known work outside of academia is his 2011 book SuperCooperators: Altruism, Evolution and Why We Need Each Other to Succeed. Another work, Evolution, Games, and God, explores the interplay between theology and evolutionary theology. Nowak, a Roman Catholic, frequently lectures about religion and was co-director with Sarah Coakley of the Evolution and Theology of Cooperation project at Harvard University.
Early life and education
Nowak was born April 7, 1965 in Vienna, Austria. He studied at Albertus Magnus Gymnasium and the University of Vienna, earning a doctorate in biochemistry and mathematics in 1989. He worked with Peter Schuster on quasi-species theory an
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https://en.wikipedia.org/wiki/Disjoint%20union%20%28topology%29
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In general topology and related areas of mathematics, the disjoint union (also called the direct sum, free union, free sum, topological sum, or coproduct) of a family of topological spaces is a space formed by equipping the disjoint union of the underlying sets with a natural topology called the disjoint union topology. Roughly speaking, in the disjoint union the given spaces are considered as part of a single new space where each looks as it would alone and they are isolated from each other.
The name coproduct originates from the fact that the disjoint union is the categorical dual of the product space construction.
Definition
Let {Xi : i ∈ I} be a family of topological spaces indexed by I. Let
be the disjoint union of the underlying sets. For each i in I, let
be the canonical injection (defined by ). The disjoint union topology on X is defined as the finest topology on X for which all the canonical injections are continuous (i.e.: it is the final topology on X induced by the canonical injections).
Explicitly, the disjoint union topology can be described as follows. A subset U of X is open in X if and only if its preimage is open in Xi for each i ∈ I. Yet another formulation is that a subset V of X is open relative to X iff its intersection with Xi is open relative to Xi for each i.
Properties
The disjoint union space X, together with the canonical injections, can be characterized by the following universal property: If Y is a topological space, and fi : Xi → Y is a
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https://en.wikipedia.org/wiki/Electromagnetic%20shielding
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In electrical engineering, electromagnetic shielding is the practice of reducing or redirecting the electromagnetic field (EMF) in a space with barriers made of conductive or magnetic materials. It is typically applied to enclosures, for isolating electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs (). Electromagnetic shielding that blocks radio frequency (RF) electromagnetic radiation is also known as RF shielding.
EMF shielding serves to minimize electromagnetic interference. The shielding can reduce the coupling of radio waves, electromagnetic fields, and electrostatic fields. A conductive enclosure used to block electrostatic fields is also known as a Faraday cage. The amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of holes in a shield to an incident electromagnetic field.
Materials used
Typical materials used for electromagnetic shielding include thin layer of metal, sheet metal, metal screen, and metal foam. Common sheet metals for shielding include copper, brass, nickel, silver, steel, and tin. Shielding effectiveness, that is, how well a shield reflects or absorbs/suppresses electromagnetic radiation, is affected by the physical properties of the metal. These may include conductivity, solderability, permeability, thickness, and weight. A metal's propert
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https://en.wikipedia.org/wiki/Journal%20of%20Genetics
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The Journal of Genetics is a peer-reviewed scientific journal in the field of genetics and evolution. It was established in 1910 by the British geneticists William Bateson and Reginald Punnett and is one of the oldest genetics journals. It was later edited by J.B.S. Haldane, who emigrated to India in 1957, and continued publishing the journal from there.
On Haldane's death in 1964, his second wife Helen Spurway continued to publish the journal with Madhav Gadgil, H. Sharat Chandra, and Suresh Jayakar as editors until Spurway died in 1977 and the journal ceased publication. With the permission of Naomi Mitchison, Haldane's sister, it was revived in 1985 and has been published by the Indian Academy of Sciences, currently in collaboration with Springer Science+Business Media, since then. All volumes published between 1910 and 1994 (vol. 1-73) are available free on the website of the Indian Academy of Sciences.
According to the Journal Citation Reports, the journal has a 2019 impact factor of 0.993.
It adopted the "Continuous Article Publication" (CAP) mode from January 2019.
References
External links
Publications established in 1910
Genetics journals
English-language journals
Springer Science+Business Media academic journals
Quarterly journals
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https://en.wikipedia.org/wiki/Paul%20Walden
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Paul Walden (; ; ; 26 July 1863 – 22 January 1957) was a Russian, Latvian and German chemist known for his work in stereochemistry and history of chemistry. In particular he invented the stereochemical reaction known as Walden inversion and synthesized the first room-temperature ionic liquid, ethylammonium nitrate.
Early life and education
Walden was born in Rozulas in present-day Stalbe parish, Pārgauja municipality, Latvia in a large Latvian peasant family. At the age of four, he lost his father and later his mother. Thanks to financial support from his two older brothers who lived in Riga (one was a merchant and another served as a lieutenant) Walden managed to complete his education – first graduated with honors from the district school in the town of Cēsis (1876), and then from the Riga Technical High School (1882).
In December 1882, he enrolled into the Riga Technical University and became seriously interested in chemistry. In 1886, he published his first scientific study on the color evaluation of the reactions of nitric and nitrous acid with various reagents and establishing the limits of sensitivity of the color method to detection of nitric acid.
In April 1887, Walden was appointed a member of the Russian Physico-chemical Society. During this time, Walden started his collaboration with Wilhelm Ostwald (Nobel Prize in Chemistry 1909) which greatly influenced his development as a scientist. Their first work together was published in 1887 and was devoted to the dep
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https://en.wikipedia.org/wiki/Harold%20McGee
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Harold James McGee (born October 3, 1951) is an American author who writes about the chemistry and history of food science and cooking. He is best known for his seminal book On Food and Cooking: The Science and Lore of the Kitchen first published in 1984 and revised in 2004.
Education
McGee was educated at the California Institute of Technology (Caltech), initially to study astronomy, but graduating with a B.S. in Literature in 1973. He went on to do a Ph.D. on the romantic poetry of John Keats supervised by Harold Bloom at Yale University, graduating in 1978.
Career
Before becoming a food science writer, McGee was a literature and writing instructor at Yale. McGee has also written for Nature, Health, The New York Times, the World Book Encyclopedia, The Art of Eating, Food & Wine, Fine Cooking, and Physics Today and lectured on kitchen chemistry at cooking schools, universities, The Oxford Symposia on Food and Cookery, the Denver Natural History Museum and the Fermi National Accelerator Laboratory. For a brief time he wrote a regular column for the New York Times, The Curious Cook, which examined, and often debunked, conventional kitchen wisdom. His latest book is Nose dive: a field guide to the world's smells (2020).
With Dave Arnold and Nils Norén, McGee teaches a three-day class, The Harold McGee Lecture Series, at The French Culinary Institute in New York City.
Awards and honors
McGee is a visiting scholar at Harvard University. His book On Food and Cooking has won
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https://en.wikipedia.org/wiki/Cliff%20Jenkins
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Cliff Jenkins (born ) is a former city councillor in Toronto, Ontario, Canada. He represented Ward 25 which was one of the two Don Valley West wards, from 2003 to 2010.
Jenkins was born in Hamilton to a working-class family. He attended McMaster University on a scholarship, and graduated with an undergraduate mathematics degree. He then went to the University of Toronto where he obtained a master's degree in mathematics and a bachelor's degree in education. He briefly worked as a high school math teacher before joining IBM Canada. He eventually rose to be a client executive at IBM.
He first rose to prominence as the president of the York Mills Ratepayers Association. He was elected to Toronto City Council in the 2003 municipal election after incumbent Joanne Flint was appointed to the Ontario Municipal Board.
In office, was noted for concern for the City's financial state. He worked on three key objectives:
1. Municipal election finance reform: To reduce undue influence in City business by special interest groups, he and fellow Councillors Michael Walker and Chin Lee successfully advocated that the Ontario government pass legislation enabling reform. Toronto City Council then adopted a by-law to implement their recommendations—including the prohibition of election contributions by corporations and unions.
2. Making transit an essential service: To prevent TTC strikes and lockouts that result in gridlock and prevent people from getting to employment, school and medi
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https://en.wikipedia.org/wiki/De%20Bruijn%20sequence
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In combinatorial mathematics, a de Bruijn sequence of order n on a size-k alphabet A is a cyclic sequence in which every possible length-n string on A occurs exactly once as a substring (i.e., as a contiguous subsequence). Such a sequence is denoted by and has length , which is also the number of distinct strings of length n on A. Each of these distinct strings, when taken as a substring of , must start at a different position, because substrings starting at the same position are not distinct. Therefore, must have at least symbols. And since has exactly symbols, de Bruijn sequences are optimally short with respect to the property of containing every string of length n at least once.
The number of distinct de Bruijn sequences is
The sequences are named after the Dutch mathematician Nicolaas Govert de Bruijn, who wrote about them in 1946. As he later wrote, the existence of de Bruijn sequences for each order together with the above properties were first proved, for the case of alphabets with two elements, by . The generalization to larger alphabets is due to . Automata for recognizing these sequences are denoted as de Bruijn automata.
In most applications, A = {0,1}.
History
The earliest known example of a de Bruijn sequence comes from Sanskrit prosody where, since the work of Pingala, each possible three-syllable pattern of long and short syllables is given a name, such as 'y' for short–long–long and 'm' for long–long–long. To remember these names, the mnemonic yamā
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https://en.wikipedia.org/wiki/James%20Cooley
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James William Cooley (1926 – June 29, 2016) was an American mathematician. Cooley received a B.A. degree in 1949 from Manhattan College, Bronx, NY, an M.A. degree in 1951 from Columbia University, New York, NY, and a Ph.D. degree in 1961 in applied mathematics from Columbia University. He was a programmer on John von Neumann's computer at the Institute for Advanced Study, Princeton, NJ, from 1953 to 1956, where he notably programmed the Blackman–Tukey transformation.
He worked on quantum mechanical computations at the Courant Institute, New York University, from 1956 to 1962, when he joined the Research Staff at the IBM Watson Research Center, Yorktown Heights, NY. Upon retirement from IBM in 1991, he joined the Department of Electrical Engineering, University of Rhode Island, Kingston, where he served on the faculty of the computer engineering program.
His most significant contribution to the world of mathematics and digital signal processing is re-discovering the fast Fourier transform, which he co-developed with John Tukey (see Cooley–Tukey FFT algorithm) while working for the research division of IBM in 1965.
The motivation for it was provided by Dr. Richard L. Garwin at IBM Watson Research who was concerned about verifying a nuclear arms treaty with the Soviet Union for the SALT talks. Garwin thought that if he had a very much faster Fourier Transform he could plant sensors in the ground in countries surrounding the Soviet Union. He suggested to both Cooley and Tukey
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https://en.wikipedia.org/wiki/Pi%20Mu%20Epsilon
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Pi Mu Epsilon ( or ) is the U.S. honorary national mathematics society.
The society was founded at Syracuse University on , by Professor Edward Drake Roe, Jr, and currently has chapters at 371 institutions across the US.
Goals
Pi Mu Epsilon is dedicated to the promotion of mathematics and recognition of students who successfully pursue mathematical understanding. To promote mathematics, the National Pi Mu Epsilon Council co-sponsors an annual conference in conjunction with the Mathematical Association of America.
The society also publishes a semi-annual journal, the Pi Mu Epsilon Journal, which both presents research papers particularly focusing on student authored papers, as well as a problem section.
The Richard V. Andree Awards are given by the organization to undergraduates whose articles in the Journal have been judged as containing the best content for the year. Andree served as the editor of the journal, as well as President and Secretary-Treasurer of the organization.
Membership
A person meeting any one of the following four sets of qualifications may be elected to membership by a chapter. This election shall be irrespective of sex, religion, race, or national origin:
Undergraduate students who have completed at least the equivalent of two semesters of calculus and two additional courses in mathematics, at or above the calculus level, all of which lead to the fulfillment of the requirements for a major in the mathematical sciences. In addition, such students must
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https://en.wikipedia.org/wiki/Approach%20space
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In topology, a branch of mathematics, approach spaces are a generalization of metric spaces, based on point-to-set distances, instead of point-to-point distances. They were introduced by Robert Lowen in 1989, in a series of papers on approach theory between 1988 and 1995.
Definition
Given a metric space (X, d), or more generally, an extended pseudoquasimetric (which will be abbreviated ∞pq-metric here), one can define an induced map d: X × P(X) → [0,∞] by d(x, A) = inf{d(x, a) : a ∈ A}. With this example in mind, a distance on X is defined to be a map X × P(X) → [0,∞] satisfying for all x in X and A, B ⊆ X,
d(x, {x}) = 0,
d(x, Ø) = ∞,
d(x, A∪B) = min(d(x, A), d(x, B)),
For all 0 ≤ ε ≤ ∞, d(x, A) ≤ d(x, A(ε)) + ε,
where we define A(ε) = {x : d(x, A) ≤ ε}.
(The "empty infimum is positive infinity" convention is like the nullary intersection is everything convention.)
An approach space is defined to be a pair (X, d) where d is a distance function on X. Every approach space has a topology, given by treating A → A(0) as a Kuratowski closure operator.
The appropriate maps between approach spaces are the contractions. A map f: (X, d) → (Y, e) is a contraction if e(f(x), f[A]) ≤ d(x, A) for all x ∈ X and A ⊆ X.
Examples
Every ∞pq-metric space (X, d) can be distanced to (X, d), as described at the beginning of the definition.
Given a set X, the discrete distance is given by d(x, A) = 0 if x ∈ A and d(x, A) = ∞ if x ∉ A. The induced topology is the discrete topology.
Given a
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https://en.wikipedia.org/wiki/Dehydration%20reaction
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In chemistry, a dehydration reaction is a chemical reaction that involves the loss of water from the reacting molecule or ion. Dehydration reactions are common processes, the reverse of a hydration reaction.
Dehydration reactions in organic chemistry
Esterification
The classic example of a dehydration reaction is the Fischer esterification, which involves treating a carboxylic acid with an alcohol to give an ester
RCO2H + R′OH RCO2R′ + H2O
Often such reactions require the presence of a dehydrating agent, i.e. a substance that reacts with water.
Etherification
Two monosaccharides, such as glucose and fructose, can be joined together (to form saccharose) using dehydration synthesis. The new molecule, consisting of two monosaccharides, is called a disaccharide.
Nitrile formation
Nitriles are often prepared by dehydration of primary amides.
RC(O)NH2 → RCN + H2O
Ketene formation
Ketene is produced by heating acetic acid and trapping the product:
CH3CO2H → CH2=C=O + H2O
Alkene formation
Alkenes can be made from alcohols by dehydration. This conversion, among others, is a key reaction in converting biomass to liquid fuels. The conversion of ethanol to ethene is a fundamental example:
CH3CH2OH → H2C=CH2 + H2O
The reaction is slow in the absence of acid catalysts such as sulfuric acid and certain zeolites.
Some alcohols are prone to dehydration. 3-Hydroxylcarbonyls, called aldols, release water upon standing at room temperature:
RC(O)CH2CH(OH)R' → RC(O)CH=CHR'
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https://en.wikipedia.org/wiki/Russian%20honey%20bee
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The Russian honeybee refers to honey bees (Apis mellifera) that originate in the Primorsky Krai region of Russia. This strain of bee was imported into the United States in 1997 by the USDA Agricultural Research Service's Honeybee Breeding, Genetics & Physiology Laboratory in Baton Rouge, Louisiana, in response to severe declines in bee populations caused by infestations of parasitic mites, and has been used in breeding programs to improve existing stocks. Many Russian queens openly mate with drones from various stock, creating colonies that are genetically hybrid. Some of these 'uncontrolled' hybrids may exhibit "increased aggressiveness, reduced honey production and a decrease in their ability to withstand mites and detrimental expressions of other traits as well."
Breeding program
In conjunction with the staff at the Baton Rouge Bee Laboratory, the Russian Honey Bee Breeders Association (RHBA) was conceived in the late 1990s, and works to certify apiarists who maintain only pure-bred Russian honey bees. These stocks are bred and DNA tested for resistance to Varroa mites and increased honey production. Their charge is as follows: "The primary purpose of the Russian Honey Bee Breeders Association is to maintain and improve the genetic lines of Russian honey bees through prorogation and selective breeding." In order to ensure pure-bred stock, an isolated mating site, a barrier island in Louisiana, was chosen as the location for this program. This program is not static as ma
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https://en.wikipedia.org/wiki/Derived%20set%20%28mathematics%29
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In mathematics, more specifically in point-set topology, the derived set of a subset of a topological space is the set of all limit points of It is usually denoted by
The concept was first introduced by Georg Cantor in 1872 and he developed set theory in large part to study derived sets on the real line.
Definition
The derived set of a subset of a topological space denoted by is the set of all points that are limit points of that is, points such that every neighbourhood of contains a point of other than itself.
Examples
If is endowed with its usual Euclidean topology then the derived set of the half-open interval is the closed interval
Consider with the topology (open sets) consisting of the empty set and any subset of that contains 1. The derived set of is
Properties
If and are subsets of the topological space then the derived set has the following properties:
implies
implies
A subset of a topological space is closed precisely when that is, when contains all its limit points. For any subset the set is closed and is the closure of (that is, the set ).
The derived set of a subset of a space need not be closed in general. For example, if with the trivial topology, the set has derived set which is not closed in But the derived set of a closed set is always closed.
In addition, if is a T1 space, the derived set of every subset of is closed in
Two subsets and are separated precisely when they are disjoint and each is d
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https://en.wikipedia.org/wiki/Elementary%20arithmetic
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Elementary arithmetic is a branch of mathematics involving basic numerical operations, namely addition, subtraction, multiplication, and division. Due to its low level of abstraction, broad range of application, and position as the foundation of all mathematics, elementary arithmetic is generally the first critical branch of mathematics to be taught in schools.
Digits
Symbols called digits are used to represent the value of numbers in a numeral system. The most commonly used digits are the Arabic numerals (0 to 9). The Hindu-Arabic numeral system is the most commonly used numeral system, being a positional notation system used to represent numbers using these digits.
Successor function and size
In elementary arithmetic, the successor of a natural number (including zero) is the result of adding one to that number, whereas the predecessor of a natural number (excluding zero) is the result obtained by subtracting one from that number. For example, the successor of zero is one and the predecessor of eleven is ten ( and ). Every natural number has a successor, and all natural numbers (except zero) have a predecessor.
If one number is greater than () another number, then the latter is less than () the first one. For example, three is less than eight (), and eight is greater than three ().
Counting
Counting involves assigning a natural number to each object in a set, starting with one for the first object and increasing by one for each subsequent object. The number of objects
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https://en.wikipedia.org/wiki/Sigma-ideal
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In mathematics, particularly measure theory, a -ideal, or sigma ideal, of a σ-algebra (, read "sigma") is a subset with certain desirable closure properties. It is a special type of ideal. Its most frequent application is in probability theory.
Let be a measurable space (meaning is a -algebra of subsets of ). A subset of is a -ideal if the following properties are satisfied:
;
When and then implies ;
If then
Briefly, a sigma-ideal must contain the empty set and contain subsets and countable unions of its elements. The concept of -ideal is dual to that of a countably complete (-) filter.
If a measure is given on the set of -negligible sets ( such that ) is a -ideal.
The notion can be generalized to preorders with a bottom element as follows: is a -ideal of just when
(i')
(ii') implies and
(iii') given a sequence there exists some such that for each
Thus contains the bottom element, is downward closed, and satisfies a countable analogue of the property of being upwards directed.
A -ideal of a set is a -ideal of the power set of That is, when no -algebra is specified, then one simply takes the full power set of the underlying set. For example, the meager subsets of a topological space are those in the -ideal generated by the collection of closed subsets with empty interior.
See also
References
Bauer, Heinz (2001): Measure and Integration Theory. Walter de Gruyter GmbH & Co. KG, 10785 Berlin, Germany.
Measure theory
Families of sets
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https://en.wikipedia.org/wiki/Eric%20F.%20Wieschaus
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Eric Francis Wieschaus (born June 8, 1947 in South Bend, Indiana) is an American evolutionary developmental biologist and 1995 Nobel Prize-winner.
Early life
Born in South Bend, Indiana, he attended John Carroll Catholic High School in Birmingham, Alabama before attending the University of Notre Dame for his undergraduate studies (B.S., biology), and Yale University (Ph.D., biology) for his graduate work.
Scientific career
In 1978, he moved to his first independent job, at the European Molecular Biology Laboratory in Heidelberg, Germany and moved from Heidelberg to Princeton University in the United States in 1981.
Much of his research has focused on embryogenesis in the fruit fly Drosophila melanogaster, specifically in the patterning that occurs in the early Drosophila embryo. Most of the gene products used by the embryo at these stages are already present in the unfertilized egg and were produced by maternal transcription during oogenesis. A small number of gene products, however, are supplied by transcription in the embryo itself. He has focused on these "zygotically" active genes because he believes the temporal and spatial pattern of their transcription may provide the triggers controlling the normal sequence of embryonic development. Saturation of all the possible mutations on each chromosome by random events to test embryonic lethality was done by Eric Wieschaus. This body of science eventually was termed the Heidelberg screen.
In 1995, he was awarded the Nobel P
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https://en.wikipedia.org/wiki/PBKDF2
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In cryptography, PBKDF1 and PBKDF2 (Password-Based Key Derivation Function 1 and 2) are key derivation functions with a sliding computational cost, used to reduce vulnerability to brute-force attacks.
PBKDF2 is part of RSA Laboratories' Public-Key Cryptography Standards (PKCS) series, specifically PKCS#5 v2.0, also published as Internet Engineering Task Force's RFC2898. It supersedes PBKDF1, which could only produce derived keys up to 160 bits long. RFC8018 (PKCS#5 v2.1), published in 2017, recommends PBKDF2 for password hashing.
Purpose and operation
PBKDF2 applies a pseudorandom function, such as hash-based message authentication code (HMAC), to the input password or passphrase along with a salt value and repeats the process many times to produce a derived key, which can then be used as a cryptographic key in subsequent operations. The added computational work makes password cracking much more difficult, and is known as key stretching.
When the standard was written in the year 2000 the recommended minimum number of iterations was 1,000, but the parameter is intended to be increased over time as CPU speeds increase. A Kerberos standard in 2005 recommended 4,096 iterations; Apple reportedly used 2,000 for iOS 3, and 10,000 for iOS 4; while LastPass in 2011 used 5,000 iterations for JavaScript clients and 100,000 iterations for server-side hashing. In 2023, OWASP recommended to use 600,000 iterations for PBKDF2-HMAC-SHA256 and 210,000 for PBKDF2-HMAC-SHA512.
Having a sal
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https://en.wikipedia.org/wiki/Todd%20class
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In mathematics, the Todd class is a certain construction now considered a part of the theory in algebraic topology of characteristic classes. The Todd class of a vector bundle can be defined by means of the theory of Chern classes, and is encountered where Chern classes exist — most notably in differential topology, the theory of complex manifolds and algebraic geometry. In rough terms, a Todd class acts like a reciprocal of a Chern class, or stands in relation to it as a conormal bundle does to a normal bundle.
The Todd class plays a fundamental role in generalising the classical Riemann–Roch theorem to higher dimensions, in the Hirzebruch–Riemann–Roch theorem and the Grothendieck–Hirzebruch–Riemann–Roch theorem.
History
It is named for J. A. Todd, who introduced a special case of the concept in algebraic geometry in 1937, before the Chern classes were defined. The geometric idea involved is sometimes called the Todd-Eger class. The general definition in higher dimensions is due to Friedrich Hirzebruch.
Definition
To define the Todd class where is a complex vector bundle on a topological space , it is usually possible to limit the definition to the case of a Whitney sum of line bundles, by means of a general device of characteristic class theory, the use of Chern roots (aka, the splitting principle). For the definition, let
be the formal power series with the property that the coefficient of in is 1, where denotes the -th Bernoulli number. Consider the coeffic
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https://en.wikipedia.org/wiki/Half-integer
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In mathematics, a half-integer is a number of the form
where is a whole number. For example,
are all half-integers. The name "half-integer" is perhaps misleading, as the set may be misunderstood to include numbers such as 1 (being half the integer 2). A name such as "integer-plus-half" may be more accurate, but even though not literally true, "half integer" is the conventional term. Half-integers occur frequently enough in mathematics and in quantum mechanics that a distinct term is convenient.
Note that halving an integer does not always produce a half-integer; this is only true for odd integers. For this reason, half-integers are also sometimes called half-odd-integers. Half-integers are a subset of the dyadic rationals (numbers produced by dividing an integer by a power of two).
Notation and algebraic structure
The set of all half-integers is often denoted
The integers and half-integers together form a group under the addition operation, which may be denoted
However, these numbers do not form a ring because the product of two half-integers is not a half-integer; e.g. The smallest ring containing them is , the ring of dyadic rationals.
Properties
The sum of half-integers is a half-integer if and only if is odd. This includes since the empty sum 0 is not half-integer.
The negative of a half-integer is a half-integer.
The cardinality of the set of half-integers is equal to that of the integers. This is due to the existence of a bijection from the integers to th
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https://en.wikipedia.org/wiki/James%20Rothman
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James Edward Rothman (born November 3, 1950) is an American biochemist. He is the Fergus F. Wallace Professor of Biomedical Sciences at Yale University, the Chairman of the Department of Cell Biology at Yale School of Medicine, and the Director of the Nanobiology Institute at the Yale West Campus. Rothman also concurrently serves as adjunct professor of physiology and cellular biophysics at Columbia University and a research professor at the UCL Queen Square Institute of Neurology, University College London.
Rothman was awarded the 2013 Nobel Prize in Physiology or Medicine, for his work on vesicle trafficking (shared with Randy Schekman and Thomas C. Südhof). He received many other honors including the King Faisal International Prize in 1996, the Louisa Gross Horwitz Prize from Columbia University and the Albert Lasker Award for Basic Medical Research both in 2002.
Education
Rothman earned his high school diploma from Pomfret School in 1967, then received his B.A. in physics at Yale University in 1971 and his Ph.D. in biological chemistry at Harvard in 1976 working with Eugene Patrick Kennedy.
Career and research
Following his Ph.D., Rothman did postdoctoral research with Harvey Lodish at Massachusetts Institute of Technology working on glycosylation of membrane proteins. He moved to the Department of Biochemistry at Stanford University in 1978. He was at Princeton University, from 1988 to 1991, before coming to New York to found the Department of Cellular Biochemistry an
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https://en.wikipedia.org/wiki/Randy%20Schekman
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Randy Wayne Schekman (born December 30, 1948) is an American cell biologist at the University of California, Berkeley, former editor-in-chief of Proceedings of the National Academy of Sciences and former editor of Annual Review of Cell and Developmental Biology. In 2011, he was announced as the editor of eLife, a new high-profile open-access journal published by the Howard Hughes Medical Institute, the Max Planck Society and the Wellcome Trust launching in 2012. He was elected to the National Academy of Sciences in 1992. Schekman shared the 2013 Nobel Prize for Physiology or Medicine with James Rothman and Thomas C. Südhof for their ground-breaking work on cell membrane vesicle trafficking.
Early life and education
Schekman was born in Saint Paul, Minnesota, to Alfred Schekman, an electrical engineer and computer software designer and Esther (Bader) Schekman. His family were Jewish emigrants from Russia and Bessarabia. In the late 1950s his family moved to the new suburban community of Rossmoor, located in Orange County next to Long Beach. He graduated from Western High School in Anaheim, California, in 1966. He received a BA in molecular biology from the University of California in Los Angeles (UCLA), in 1971. He spent his third year at the University of Edinburgh in Scotland, as an exchange student. He received a PhD in 1975 from Stanford University for research on DNA replication working with Arthur Kornberg. After joining the faculty at University of California Berkel
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https://en.wikipedia.org/wiki/Unitarian%20trick
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In mathematics, the unitarian trick is a device in the representation theory of Lie groups, introduced by for the special linear group and by Hermann Weyl for general semisimple groups. It applies to show that the representation theory of some group G is in a qualitative way controlled by that of some other compact group K. An important example is that in which G is the complex general linear group, and K the unitary group acting on vectors of the same size. From the fact that the representations of K are completely reducible, the same is concluded for those of G, at least in finite dimensions.
The relationship between G and K that drives this connection is traditionally expressed in the terms that the Lie algebra of K is a real form of that of G. In the theory of algebraic groups, the relationship can also be put that K is a dense subset of G, for the Zariski topology.
The trick works for reductive Lie groups, of which an important case are semisimple Lie groups.
Weyl's theorem
The complete reducibility of finite-dimensional linear representations of compact groups, or connected semisimple Lie groups and complex semisimple Lie algebras goes sometimes under the name of Weyl's theorem. A related result, that the universal cover of a compact semisimple Lie group is also compact, also goes by the same name.
History
Adolf Hurwitz had shown how integration over a compact Lie group could be used to construct invariants, in the cases of unitary groups and compact orthogonal
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https://en.wikipedia.org/wiki/Dean%20Hamer
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Dean Hamer (; born May 29, 1951) is an American geneticist, author, and filmmaker. He is known for his research on the role of genetics in sexual orientation and for a series of popular books and documentaries that have changed the understanding and perceptions of human sexuality and gender identity.
Education and career
Born in Montclair, New Jersey, Hamer obtained his BA at Trinity College, CT, and his PhD from Harvard Medical School. He was an independent researcher at the National Institutes of Health for 35 years, where he was the Chief of Gene Structure and Regulation Section at the U.S. National Cancer Institute; upon retirement in 2011 he was designated Scientist Emeritus. Hamer has won numerous awards including the Trinity College Thompson History Prize, Maryland Distinguished Young Scientist Award, Ariens Kappers Award for Neurobiology, New York Times book-of-the year author, and an Emmy Award.
Biotechnology research
Hamer invented the first method for introducing new genes into animal cells using SV40 vectors while a graduate student at Harvard Medical School. This approach was used to produce a variety of biomedical products including human growth hormone and a vaccine for Hepatitis B, resulting in 4 US patents.
At NIH, Hamerʻs lab initially focused on the metallothionein gene system. They elucidated the mechanism of induction of yeast metallothionein by copper ions, one of the first eukaryotic gene regulatory systems to be understood at the molecular level and
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https://en.wikipedia.org/wiki/Veronese%20surface
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In mathematics, the Veronese surface is an algebraic surface in five-dimensional projective space, and is realized by the Veronese embedding, the embedding of the projective plane given by the complete linear system of conics. It is named after Giuseppe Veronese (1854–1917). Its generalization to higher dimension is known as the Veronese variety.
The surface admits an embedding in the four-dimensional projective space defined by the projection from a general point in the five-dimensional space. Its general projection to three-dimensional projective space is called a Steiner surface.
Definition
The Veronese surface is the image of the mapping
given by
where denotes homogeneous coordinates. The map is known as the Veronese embedding.
Motivation
The Veronese surface arises naturally in the study of conics. A conic is a degree 2 plane curve, thus defined by an equation:
The pairing between coefficients and variables is linear in coefficients and quadratic in the variables; the Veronese map makes it linear in the coefficients and linear in the monomials. Thus for a fixed point the condition that a conic contains the point is a linear equation in the coefficients, which formalizes the statement that "passing through a point imposes a linear condition on conics".
Veronese map
The Veronese map or Veronese variety generalizes this idea to mappings of general degree d in n+1 variables. That is, the Veronese map of degree d is the map
with m given by the multiset coefficie
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https://en.wikipedia.org/wiki/Stochastic%20electrodynamics
|
Stochastic electrodynamics (SED) is a variant of classical electrodynamics (CED) of theoretical physics. SED consists of a set of controversial theories that posit the existence of a classical Lorentz invariant radiation field having statistical properties similar to that of the electromagnetic zero-point field (ZPF) of quantum electrodynamics (QED).
Classical background field
The background field is introduced as a Lorentz force in the (classical) Abraham–Lorentz–Dirac equation (see: Abraham–Lorentz–Dirac force), where the classical statistics of the electric and magnetic fields and quadratic combinations thereof are chosen to match the vacuum expectation values of the equivalent operators in QED. The field is generally represented as a discrete sum of Fourier components each with amplitude and phase that are independent classical random variables, distributed so that the statistics of the fields are isotropic and unchanged under boosts. This prescription is such that each Fourier mode at frequency (f) is expected to have an energy of hf/2, equaling that of the ground state of the vacuum modes of QED. Unless cut off, the total field has an infinite energy density, with a spectral energy density (per unit frequency per unit volume) [2h/c3]f3 where h is Planck's constant. Consequently, the background field is a classical version of the electromagnetic ZPF of QED, though in SED literature the field is commonly referred to simply as 'the ZPF' without making that distinction. A
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https://en.wikipedia.org/wiki/Peter%20Simons%20%28academic%29
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Peter Murray Simons, (born 23 March 1950) is a British retired philosopher and academic. From 2009 to 2016, he was Professor of Moral Philosophy at Trinity College Dublin; he is now professor emeritus. He is known for his work with Kevin Mulligan and Barry Smith on metaphysics and the history of Austrian philosophy. Since 2018 he is visiting professor at the University of Italian Switzerland.
Biography
Simons studied at the University of Manchester, and has held teaching posts at the University of Bolton, from which he holds an honorary doctorate, the University of Salzburg, where he is Honorary Professor of Philosophy, and the University of Leeds. He has been President of the European Society for Analytic Philosophy and is current director of the Franz Brentano Foundation.
His research interests include metaphysics and ontology, the history of logic, the history of Central European Philosophy, particularly in Austria and Poland in the 19th and 20th centuries, and the application of metaphysics to engineering and other non-philosophical disciplines. He is the author or co-author of five books and over 290 articles.
Awards
FBA: Fellow of the British Academy (elected July 2004)
Member of Academia Europaea (elected 2006)
Member of the Royal Irish Academy (elected 2013)
Foreign Member of the Polish Academy of Sciences (elected 2018)
Publications
Parts. A Study In Ontology, Oxford: Clarendon Press, 1987.
Philosophy and Logic in Central Europe from Bolzano to Tarski. S
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https://en.wikipedia.org/wiki/University%20of%20Colombo
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The University of Colombo (informally Colombo University or UoC) is a public research university located primarily in Colombo, Sri Lanka. It is the oldest institution of modern higher education in Sri Lanka. Specialised in the fields of natural, social, and applied sciences as well as mathematics, computer sciences, and law. It is ranked among the top 10 universities in South Asia.
The University of Colombo was founded in 1921 as University College Colombo, affiliated to the University of London. Degrees were issued to its students from 1923 onwards. The university traces its roots to 1870 when the Ceylon Medical School was established. UoC has produced notable alumni in the fields of science, law, economics, business, literature, and politics.
Overview
The university is a state university, with most of its funding coming from the central government via the University Grants Commission (UGC). Therefore, as with all other state universities in Sri Lanka, the UGC recommends its vice-chancellor for appointment by the President of Sri Lanka and makes appointments of its administrative staff. Its motto is "Buddhih Sarvatra Bhrajate", which means "Wisdom shines forth everywhere" in Sanskrit.
With a student population of over 11,000, the university is made up of seven faculties with 43 academic departments and eight other institutions. Most faculties offer both undergraduate and postgraduate degrees, with some offering courses for external students and distance-learning programs.
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https://en.wikipedia.org/wiki/Francis%20J.%20Harvey
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Francis Joseph Harvey (born July 8, 1943) served as the nineteenth Secretary of the United States Army from November 19, 2004, to March 9, 2007.
Education and family
Francis J. Harvey II was born and raised in Latrobe, Pennsylvania. He earned his doctorate in Metallurgy and Materials Science from the University of Pennsylvania and his Bachelor of Science at the University of Notre Dame in Metallurgical Engineering and Materials Science.
As of 2013, he and his wife of fifty-two years, Mary, have two boys. They also have five grandchildren.
Career
The majority of Harvey's career was spent with corporations that provided products and services to the federal government, particularly the United States Department of Defense, and included a year of government service. He was involved in more than twenty major defense programs across the entire spectrum from undersea to outer space, including tanks, missiles, submarines, surface ships, aircraft and satellites. In addition, he was a member of the Army Science Board in the late 1990s, traveling to numerous U.S. Army installations, and participated in early studies that helped define the Future Combat System. Harvey also served for one year as a White House Fellow and assistant in the immediate office of the Secretary of Defense, Harold Brown, in the late 1970s.
Harvey held various professional, management and executive positions within the Westinghouse Corporation from 1969 to 1997, including President of the Electronics Systems G
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https://en.wikipedia.org/wiki/Society%20of%20Mathematicians%2C%20Physicists%20and%20Astronomers%20of%20Slovenia
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The Society of Mathematicians, Physicists and Astronomers of Slovenia (Slovene: Društvo matematikov, fizikov in astronomov Slovenije, DMFA) is the main Slovene society in the field of mathematics, physics and astronomy.
The Society is occupied with pedagogical activity and with the popularization of mathematics, recreational mathematics, physics, astronomy and with organizing competitions at all levels of education.
It takes care of publicistic and editorial activity, where we should mention its gazette Obzornik za matematiko in fiziko (A Review for Mathematics and Physics), a magazine for secondary schools Presek (A Section), literary collection Sigma and other literary editions.
The current president of the Society is Dragan Mihailovic (since 2017) and the vice-president is Nada Razpet.
The DMFA collaborates with the European Mathematical Society (EMS), the European Physical Society (EPS) and many other related societies around the world.
Honourable members
The Society grants an honourable membership to a person or persons, which have contributed significantly to advance of mathematical and natural sciences in Slovenia, and to development of the Society.
External links
DMFA Slovenije
Info at EPS
Mathematical societies
Non-profit organizations based in Slovenia
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https://en.wikipedia.org/wiki/Leo%20Irakliotis
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Leo Irakliotis is a computer engineer. His early work was on optical information processing. With Leo Kadanoff he founded the Center for Presentation of Science at the University of Chicago, where he taught computer science from 1997 until 2009.
Irakliotis earned a master's degree in theoretical physics from Miami University (Ohio) and a Ph.D. degree in Electrical and Computer Engineering from Colorado State University. In 2005, Irakliotis worked with Jef Raskin to design a new curriculum on humane interfaces and computer enterprises. The project was never completed due to Raskin's death in the same year.
References
Greek academics
Living people
Year of birth missing (living people)
University of Chicago faculty
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https://en.wikipedia.org/wiki/Leo%20Kadanoff
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Leo Philip Kadanoff (January 14, 1937 – October 26, 2015) was an American physicist. He was a professor of physics (emeritus from 2004) at the University of Chicago and a former president of the American Physical Society (APS). He contributed to the fields of statistical physics, chaos theory, and theoretical condensed matter physics.
Biography
Kadanoff was raised in New York City. He received his undergraduate degree and doctorate in physics (1960) from Harvard University. After a post-doctorate at the Niels Bohr Institute in Copenhagen, he joined the physics faculty at the University of Illinois in 1965.
Kadanoff's early research focused upon superconductivity. In the late 1960s, he studied the organization of matter in phase transitions. Kadanoff demonstrated that sudden changes in material properties (such as the magnetization of a magnet or the boiling of a fluid) could be understood in terms of scaling and universality. With his collaborators, he showed how all the experimental data then available for the changes, called second-order phase transitions, could be understood in terms of these two ideas. These same ideas have now been extended to apply to a broad range of scientific and engineering problems, and have found numerous and important applications in urban planning, computer science, hydrodynamics, biology, applied mathematics and geophysics. In recognition of these achievements, he won the Buckley Prize of the American Physical Society (1977), the Wolf Priz
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https://en.wikipedia.org/wiki/Mathematical%20chemistry
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Mathematical chemistry is the area of research engaged in novel applications of mathematics to chemistry; it concerns itself principally with the mathematical modeling of chemical phenomena. Mathematical chemistry has also sometimes been called computer chemistry, but should not be confused with computational chemistry.
Major areas of research in mathematical chemistry include chemical graph theory, which deals with topology such as the mathematical study of isomerism and the development of topological descriptors or indices which find application in quantitative structure-property relationships; and chemical aspects of group theory, which finds applications in stereochemistry and quantum chemistry. Another important area is molecular knot theory and circuit topology that describe the topology of folded linear molecules such as proteins and Nucleic Acids.
The history of the approach may be traced back to the 19th century. Georg Helm published a treatise titled "The Principles of Mathematical Chemistry: The Energetics of Chemical Phenomena" in 1894. Some of the more contemporary periodical publications specializing in the field are MATCH Communications in Mathematical and in Computer Chemistry, first published in 1975, and the Journal of Mathematical Chemistry, first published in 1987. In 1986 a series of annual conferences MATH/CHEM/COMP taking place in Dubrovnik was initiated by the late Ante Graovac.
The basic models for mathematical chemistry are molecular graph and top
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https://en.wikipedia.org/wiki/Isopropyl%20%CE%B2-D-1-thiogalactopyranoside
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{{DISPLAYTITLE:Isopropyl β-D-1-thiogalactopyranoside}}
Isopropyl β--1-thiogalactopyranoside (IPTG) is a molecular biology reagent. This compound is a molecular mimic of allolactose, a lactose metabolite that triggers transcription of the lac operon, and it is therefore used to induce protein expression where the gene is under the control of the lac operator.
Mechanism of action
Like allolactose, IPTG binds to the lac repressor and releases the tetrameric repressor from the lac operator in an allosteric manner, thereby allowing the transcription of genes in the lac operon, such as the gene coding for beta-galactosidase, a hydrolase enzyme that catalyzes the hydrolysis of β-galactosides into monosaccharides. But unlike allolactose, the sulfur (S) atom creates a chemical bond which is non-hydrolyzable by the cell, preventing the cell from metabolizing or degrading the inducer. Therefore, its concentration remains constant during an experiment.
IPTG uptake by E. coli can be independent of the action of lactose permease, since other transport pathways are also involved. At low concentration, IPTG enters cells through lactose permease, but at high concentrations (typically used for protein induction), IPTG can enter the cells independently of lactose permease.
Use in laboratory
When stored as a powder at 4 °C or below, IPTG is stable for 5 years. It is significantly less stable in solution; Sigma recommends storage for no more than a month at room temperature. IPTG is an ef
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https://en.wikipedia.org/wiki/C3
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C3, C-3, C.3, C03, C.III or C-III may refer to:
Life and biology
C3 carbon fixation in plants
C3-convertase, an enzyme
Complement component 3, a protein of the innate immune system
Apolipoprotein C3, a human very low density lipoprotein
ATC code C03 Diuretics, a subgroup of the Anatomical Therapeutic Chemical Classification System
Castavinol C3, a natural phenolic compound found in red wines
Cytochrome-c3 hydrogenase, an enzyme
Haplogroup C-M217, called C3 in older publications
In human anatomy, C3 may refer to:
Cervical vertebra 3, one of the cervical vertebrae of the vertebral column
Cervical spinal nerve 3
Clinical Cell Culture, a medical technology company
C03, Malignant neoplasm of gum ICD-10 code
C3 Collaborating for Health, a health-promotion NGO
C3: an EEG electrode site according to the 10-20 system
Military
C3, Command, control, and communications, a military concept
C-3 (plastic explosive), a plastic explosive related to C4
C-3, a United States military designation for the Ford Trimotor
the designation for several German World War I and World War II armed reconnaissance aircraft
AEG C.III
AGO C.III, a reconnaissance biplane of World War I
Albatros C.III
DFW C.III, a DFW aircraft
NAG C.III, an engine powering the Gotha G.IV aircraft
C-3, a U.S. military transport version of the Martin 4-0-4
Type C3 submarine (disambiguation), a World War II Imperial Japanese Navy cargo carrier submarine
Spanish submarine C-3
HMS C3, a 1906 British C cl
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https://en.wikipedia.org/wiki/Meanings%20of%20minor%20planet%20names%3A%2026001%E2%80%9327000
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26001–26100
|-id=002
| 26002 Angelayeung || || Angela Yu-Yun Yeung (born 1992) is a finalist in the 2010 Intel Science Talent Search (STS), a science competition for high school seniors, for her materials and bioengineering project. She attends the Davis Senior High School, Davis, California ||
|-id=003
| 26003 Amundson || || Lauren Amundson (born 1984) is the librarian/archivist for Lowell Observatory. As such, she is the curator for the Observatory's historical collection which includes extensive material from Percival Lowell's personal research and travels. ||
|-id=004
| 26004 Loriying || || Lori Ying (born 1992) is a finalist in the 2010 Intel Science Talent Search (STS), a science competition for high school seniors, for her animal sciences project. She attends the South Side High School, Rockville Centre, New York ||
|-id=005
| 26005 Alicezhao || || Alice Wei Zhao (born 1993) is a finalist in the 2010 Intel Science Talent Search (STS), a science competition for high school seniors, for her materials and bioengineering project. She attends the Sheboygan North High School, Sheboygan, Wisconsin ||
|-id=007
| 26007 Lindazhou || || Linda Zhou (born 1992) is a finalist in the 2010 Intel Science Talent Search (STS), a science competition for high school seniors, for her biochemistry project. She attends the Academy for Medical Science Technology, Hackensack, New Jersey ||
|-id=011
| 26011 Cornelius || || Frank Cornelius (born 1961), Engineering Manager at Lowell
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https://en.wikipedia.org/wiki/Sociocultural%20evolution
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Sociocultural evolution, sociocultural evolutionism or social evolution are theories of sociobiology and cultural evolution that describe how societies and culture change over time. Whereas sociocultural development traces processes that tend to increase the complexity of a society or culture, sociocultural evolution also considers process that can lead to decreases in complexity (degeneration) or that can produce variation or proliferation without any seemingly significant changes in complexity (cladogenesis). Sociocultural evolution is "the process by which structural reorganization is affected through time, eventually producing a form or structure that is qualitatively different from the ancestral form".
Most of the 19th-century and some 20th-century approaches to socioculture aimed to provide models for the evolution of humankind as a whole, arguing that different societies have reached different stages of social development. The most comprehensive attempt to develop a general theory of social evolution centering on the development of sociocultural systems, the work of Talcott Parsons (1902–1979), operated on a scale which included a theory of world history. Another attempt, on a less systematic scale, originated from the 1970s with the world-systems approach of Immanuel Wallerstein (1930-2019) and his followers.
More recent approaches focus on changes specific to individual societies and reject the idea that cultures differ primarily according to how far each one has
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https://en.wikipedia.org/wiki/Subliminal
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Subliminal may refer to:
Subliminal stimuli, sensory stimuli below an individual's threshold for conscious perception
Subliminal channel, in cryptography, a covert channel that can be used over an insecure channel
Subliminal (rapper) (born 1979), Israeli rapper and producer
Subliminal (record label), an electronic music label
Subliminal..., a 1997 album by American jazz bassist Scott Colley
Subliminal (album), Prosperity by Triple A. Tanzanite BWE MP3 Subliminals
"Subliminal", a Suicidal Tendencies song from the album Suicidal Tendencies
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https://en.wikipedia.org/wiki/Von%20Mises
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The Mises family or von Mises is the name of an Austrian noble family. Members of the family excelled especially in mathematics and economy.
Notable members
Ludwig von Mises, an Austrian-American economist of the Austrian School, older brother of Richard von Mises
Mises Institute, or the Ludwig von Mises Institute for Austrian Economics, named after Ludwig von Mises
Richard von Mises, an Austrian-American scientist and mathematician, younger brother of Ludwig von Mises
Von Mises distribution, named after Richard von Mises
Von Mises yield criterion, named after Richard von Mises
Dr. Mises, pseudonym of Gustav Fechner, a German philosopher, physicist and experimental psychologist.
Surnames of Jewish origin
Austrian noble families
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https://en.wikipedia.org/wiki/John%20Montroll
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John Montroll is an American origami artist, author, teacher, and mathematician. He has written many books on origami, promoting the single-square, no-cut, no glue approach. Montroll taught mathematics at St. Anselm's Abbey School in Washington, D.C. from 1990 to 2021.
Biography
John Montroll was born in Washington, D.C. He is the son of Elliott Waters Montroll, an American scientist and mathematician. He has a Bachelor of Arts degree in Mathematics from the University of Rochester, a Master of Arts in Electrical Engineering from the University of Michigan, and a Master of Arts in applied mathematics from the University of Maryland.
Montroll mastered his first origami book, Isao Honda's How to make Origami, at the age of six, the same age he began creating his own origami animals. He became a member of the Origami Center of America at age twelve. He attended his first origami convention at age 14. In 2021, Montroll retired from his job at St. Anselm's Abbey School in Washington, D.C., where he taught mathematics, as well as an origami class. One of John Montroll's hobbies is whistling. He claims to be able to whistle in five octaves and to have shown this talent at two whistling conventions in Louisburg, North Carolina.
John Montroll pioneered modern origami with the publication of his first book, Origami for the Enthusiast; Dover Publications, 1979, which was the first origami book where each model is folded from single square sheet and no cuts. In the same book he intr
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https://en.wikipedia.org/wiki/Conversion%20%28chemistry%29
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Conversion and its related terms yield and selectivity are important terms in chemical reaction engineering. They are described as ratios of how much of a reactant has reacted (X — conversion, normally between zero and one), how much of a desired product was formed (Y — yield, normally also between zero and one) and how much desired product was formed in ratio to the undesired product(s) (S — selectivity).
There are conflicting definitions in the literature for selectivity and yield, so each author's intended definition should be verified.
Conversion can be defined for (semi-)batch and continuous reactors and as instantaneous and overall conversion.
Assumptions
The following assumptions are made:
The following chemical reaction takes place:
,
where and are the stoichiometric coefficients. For multiple parallel reactions, the definitions can also be applied, either per reaction or using the limiting reaction.
Batch reaction assumes all reactants are added at the beginning.
Semi-Batch reaction assumes some reactants are added at the beginning and the rest fed during the batch.
Continuous reaction assumes reactants are fed and products leave the reactor continuously and in steady state.
Conversion
Conversion can be separated into instantaneous conversion and overall conversion. For continuous processes the two are the same, for batch and semi-batch there are important differences. Furthermore, for multiple reactants, conversion can be defined overall or per react
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https://en.wikipedia.org/wiki/Leachate
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A leachate is any liquid that, in the course of passing through matter, extracts soluble or suspended solids, or any other component of the material through which it has passed.
Leachate is a widely used term in the environmental sciences where it has the specific meaning of a liquid that has dissolved or entrained environmentally harmful substances that may then enter the environment. It is most commonly used in the context of land-filling of putrescible or industrial waste.
In the narrow environmental context leachate is therefore any liquid material that drains from land or stockpiled material and contains significantly elevated concentrations of undesirable material derived from the material that it has passed through.
Landfill leachate
Leachate from a landfill varies widely in composition depending on the age of the landfill and the type of waste that it contains. It usually contains both dissolved and suspended material. The generation of leachate is caused principally by precipitation percolating through waste deposited in a landfill. Once in contact with decomposing solid waste, the percolating water becomes contaminated, and if it then flows out of the waste material it is termed leachate. Additional leachate volume is produced during this decomposition of carbonaceous material producing a wide range of other materials including methane, carbon dioxide and a complex mixture of organic acids, aldehydes, alcohols and simple sugars.
The risks of leachate generation
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https://en.wikipedia.org/wiki/Ian%20Bell%20%28programmer%29
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Ian Colin Graham Bell (born 31 October 1962 in Hatfield, Hertfordshire) programmed, designed and developed the computer game Elite (1984) with David Braben, which met with much acclaim.
Education
Bell attended the independent St Albans School. He studied at Jesus College, Cambridge, graduating with a degree (1st) in Mathematics in 1985, and a Cambridge Diploma in Computer Science in 1986.
Career
Worked as a Senior Software Engineer for Autodesk. Bell was a speaker at the 2009 GameCity game festival. Bell mentioned in his speech about the impact of games:You're reaching into the minds and the imaginary spaces of children, and you're to an extent shaping their characters and their life stories. I'm glad [Elite] isn't Doom because I'm glad that even though we didn't really think in these terms, I think its effect on players and on people's lives is good, both in the sense of giving them good memories but also in making people think in different ways and awakening interest.
Game development
His work on Elite (1984), included programming in machine code using assembly. The game was based on an open-ended non-linear game model, and included revolutionary 3D graphics, at the time. Prior to Elite, he developed Free Fall, a game set inside a coriolis space station with the player controlling an alien punching astronaut, described by Bell as "the first ever Beat 'em up". Free Fall, also a game for the BBC Micro, was published by Acornsoft in 1983. Bell put later Free Fall and Elite
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https://en.wikipedia.org/wiki/Hilbert%27s%20fourth%20problem
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In mathematics, Hilbert's fourth problem in the 1900 list of Hilbert's problems is a foundational question in geometry. In one statement derived from the original, it was to find — up to an isomorphism — all geometries that have an axiomatic system of the classical geometry (Euclidean, hyperbolic and elliptic), with those axioms of congruence that involve the concept of the angle dropped, and `triangle inequality', regarded as an axiom, added.
If one assumes the continuity axiom in addition, then, in the case of the Euclidean plane, we come to the problem posed by Jean Gaston Darboux: "To determine all the calculus of variation problems in the plane whose solutions are all the plane straight lines."
There are several interpretations of the original statement of David Hilbert. Nevertheless, a solution was sought, with the German mathematician Georg Hamel being the first to contribute to the solution of Hilbert's fourth problem.
A recognized solution was given by Soviet mathematician Aleksei Pogorelov in 1973.<ref name="Pogorelov1973">А. В. Погорелов, Полное решение IV проблемы Гильберта, ДАН СССР № 208, т.1 (1973), 46–49. English translation: {{cite journal
| last1=Pogorelov | first1=A. V.
| title=A complete solution of "Hilbert's fourth problem| journal=Doklady Akademii Nauk SSSR
| volume=208
| issue=1
| date=1973
| pages=48–52}}</ref> In 1976, Armenian mathematician Rouben V. Ambartzumian proposed another proof of Hilbert's fourth problem.
Original statement
Hilbert d
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https://en.wikipedia.org/wiki/Donaldson%20Brown
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Frank Donaldson Brown (February 1, 1885 – October 2, 1965) was a financial executive and corporate director with both DuPont and General Motors Corporation. He is the originator of DuPont analysis, a widely used technique in finance.
He graduated from Virginia Tech in 1902 with a Bachelor of Science degree in Electrical Engineering. He did graduate studies in engineering at Cornell University and joined DuPont in 1909 as an explosives salesman.
In 1912 he came to the attention of DuPont treasurer John J. Raskob, who brought him into the financial activity and encouraged him to use uniform accounting procedures and statistical formulas to evaluate the company's diverse business interests.
In 1918 he assisted in arranging DuPont's purchase of a substantial stake in General Motors from previous chairman William C. Durant, and later that year became treasurer of DuPont replacing Raskob. In 1921 he became treasurer of GM to help protect DuPont's investment in the struggling auto maker, and in 1924 he was appointed to the executive board of GM.
His introduction of standard financial ratios (return on investment and return on equity) and flexible budgeting allowed the company to effectively manage its decentralized empire. During this time he worked closely with legendary GM head Alfred P. Sloan. He served as vice chairman of the board from 1937 to 1946.
Brown retired as an active executive with GM in 1946, but remained on the board until 1959 when he and 3 other directors had
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https://en.wikipedia.org/wiki/Hamilton%20O.%20Smith
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Hamilton Othanel Smith (born August 23, 1931) is an American microbiologist and Nobel laureate.
Smith graduated from University Laboratory High School of Urbana, Illinois. He attended the University of Illinois at Urbana-Champaign, but in 1950 transferred to the University of California, Berkeley, where he earned his B.A. in Mathematics in 1952 . He received his medical degree from Johns Hopkins School of Medicine in 1956. Between 1956 and 1957 Smith worked for the Washington University in St. Louis Medical Service. In 1975, he was awarded a Guggenheim Fellowship he spent at the University of Zurich.
In 1970, Smith and Kent W. Wilcox discovered the first type II restriction enzyme, that is now called as HindII. Smith went on to discover DNA methylases that constitute the other half of the bacterial host restriction and modification systems, as hypothesized by Werner Arber of Switzerland.
He was awarded the Nobel Prize in Physiology or Medicine in 1978 for discovering type II restriction enzymes with Werner Arber and Daniel Nathans as co-recipients.
He later became a leading figure in the nascent field of genomics, when in 1995 he and a team at The Institute for Genomic Research sequenced the first bacterial genome, that of Haemophilus influenzae. H. influenza was the same organism in which Smith had discovered restriction enzymes in the late 1960s. He subsequently played a key role in the sequencing of many of the early genomes at The Institute for Genomic Research, and
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https://en.wikipedia.org/wiki/Nile%20blue
|
Nile blue (or Nile blue A) is a stain used in biology and histology. It may be used with live or fixed cells, and imparts a blue colour to cell nuclei.
It may also be used in conjunction with fluorescence microscopy to stain for the presence of polyhydroxybutyrate granules in prokaryotic or eukaryotic cells. Boiling a solution of Nile blue with sulfuric acid produces Nile red (Nile blue oxazone).
Chemical and physical properties
Nile blue is a fluorescent dye. The fluorescence shows especially in nonpolar solvents with a high quantum yield.
The absorption and emission maxima of Nile blue are strongly dependent on pH and the solvents used:
The duration of Nile blue fluorescence in ethanol was measured as 1.42 ns. This is shorter than the corresponding value of Nile red with 3.65 ns. The fluorescence duration is independent on dilution in the range 10−3 to 10−8 mol/L.
Nile blue staining
Nile blue is used for histological staining of biological preparations. It highlights the distinction between neutral lipids (triglycerides, cholesteryl esters, steroids) which are stained pink and acids (fatty acids, chromolipids, phospholipids) which are stained blue.
The Nile blue staining, according to Kleeberg, uses the following chemicals:
Nile Blue A
1% acetic acid
Glycerol or glycerol gelatin
Workflow
The sample or frozen sections is/are fixated in formaldehyde, then immersed for 20 minutes in the Nile blue solution or 30 sec in nile blue A (1% w/v in distilled water) and rinse
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https://en.wikipedia.org/wiki/TST
|
TST may stand for:
Science and technology
Ternary search tree, in computer science
Transition state theory, of chemical reaction rates
TST (gene)
Tuberculin skin test
Tectonic strain theory
Total sleep time
Total station theodolite
Typed set theory, in mathematical logic
Transgressive systems tract, in sequence stratigraphy
Tail suspension test
Places
Tsim Sha Tsui, an urbanized area in Hong Kong
Tsim Sha Tsui station, a railway station there
Trang Airport in Thailand (IATA airport code)
Organisations and groups
Telesta Therapeutics, Toronto Stock Exchange symbol
TheStreet.com, NASDAQ trading symbol
Toronto School of Theology, Canada
TST-CF Express, Canadian LTL freight carrier formerly known as TST Overland Express
Tribunal Superior do Trabalho, (Superior Labor Court), Brazil federal courts
The Satanic Temple, nontheistic religious and human rights organization
Other
.TST, ExamView file extension
Tolley, Scott & Tolley, Australian winemakers
Top Secret (TST), a South Korean band
The Soccer Tournament, a sports tournament
Taiwan Standard Time, the standard time zone used in Taiwan (UTC+8).
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https://en.wikipedia.org/wiki/Mimesis%20%28mathematics%29
|
In mathematics, mimesis is the quality of a numerical method which imitates some properties of the continuum problem. The goal of numerical analysis is to approximate the continuum, so instead of solving a partial differential equation one aims to solve a discrete version of the continuum problem. Properties of the continuum problem commonly imitated by numerical methods are conservation laws, solution symmetries, and fundamental identities and theorems of vector and tensor calculus like the divergence theorem.
Both finite difference or finite element method can be mimetic; it depends on the properties that the method has.
For example, a mixed finite element method applied to Darcy flows strictly conserves the mass of the flowing fluid.
The term geometric integration denotes the same philosophy.
References
Numerical differential equations
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https://en.wikipedia.org/wiki/Accelerant
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Accelerants are substances that can bond, mix or disturb another substance and cause an increase in the speed of a natural, or artificial chemical process. Accelerants play a major role in chemistry—most chemical reactions can be hastened with an accelerant. Accelerants alter a chemical bond, speed up a chemical process, or bring organisms back to homeostasis. Accelerants are not necessarily catalysts as they may be consumed by the process.
Fire
In fire protection, the term accelerant is used very broadly to include any substance or mixture that "accelerates" the development of fire to commit arson. Chemists would distinguish an accelerant from a fuel; the terms are not, in the truest sense of chemical science, interchangeable. Some fire investigators use the term "accelerant" to mean any substance that initiates and promotes a fire without differentiating between an accelerant and a fuel. To a chemical engineer, "gasoline" is not at all considered an "accelerant"; it is more accurately considered a "fuel".
A fire is a self-sustaining, exothermic oxidation reaction that emits heat and light. When a fire is accelerated with a true accelerant like oxygen bearing liquids and gases (like ) it can produce more heat, consume the actual fuels more quickly, and increase the spread of the fire. Fires involving liquid accelerants, like gasoline, burn more quickly, but at the same temperature as fires involving ordinary fuels.
Fire investigation
Indicators of an incendiary fire o
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https://en.wikipedia.org/wiki/Shear%20modulus
|
In materials science, shear modulus or modulus of rigidity, denoted by G, or sometimes S or μ, is a measure of the elastic shear stiffness of a material and is defined as the ratio of shear stress to the shear strain:
where
= shear stress
is the force which acts
is the area on which the force acts
= shear strain. In engineering , elsewhere
is the transverse displacement
is the initial length of the area.
The derived SI unit of shear modulus is the pascal (Pa), although it is usually expressed in gigapascals (GPa) or in thousand pounds per square inch (ksi). Its dimensional form is M1L−1T−2, replacing force by mass times acceleration.
Explanation
The shear modulus is one of several quantities for measuring the stiffness of materials. All of them arise in the generalized Hooke's law:
Young's modulus E describes the material's strain response to uniaxial stress in the direction of this stress (like pulling on the ends of a wire or putting a weight on top of a column, with the wire getting longer and the column losing height),
the Poisson's ratio ν describes the response in the directions orthogonal to this uniaxial stress (the wire getting thinner and the column thicker),
the bulk modulus K describes the material's response to (uniform) hydrostatic pressure (like the pressure at the bottom of the ocean or a deep swimming pool),
the shear modulus G describes the material's response to shear stress (like cutting it with dull scissors).
These moduli are not indepe
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https://en.wikipedia.org/wiki/Edmond%20H%C3%A9bert
|
Edmond Hébert (12 June 18124 April 1890), French geologist, was born at Villefargau, Yonne.
He was educated at the College de Meaux, Auxerre, and at the École Normale in Paris. In 1836 he became professor at Meaux, in 1838 demonstrator in chemistry and physics at the École Normale, and in 1841 sub-director of studies at that school and lecturer on geology. In 1857 the degree of D. es Sc. was conferred upon him, and he was appointed professor of geology at the Sorbonne.
There he was eminently successful as a teacher, and worked with great zeal in the field, adding much to the knowledge of the Jurassic and older strata. He devoted, however, special attention to the subdivisions of the Cretaceous and Tertiary formations in France, and to their correlation with the strata in England and in southern Europe.
To him we owe the first definite arrangement of the Chalk into palaeontological zones (see "Table" in Geol. Hag., 1869, p. 200). During his later years he was regarded as the leading geologist in France.
He was elected a member of the Académie des sciences in 1877, Commander of the Legion of Honour in 1885, and he was three times president of the Geological Society of France. He died in Paris on 4 April 1890.
References
External links
Comité des travaux historiques et scientifiques: short biography (in French) and list of publications
1812 births
1890 deaths
People from Yonne
French geologists
Hebert, Edmond
Members of the French Academy of Sciences
Academic staff of th
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https://en.wikipedia.org/wiki/Condensate
|
Condensate may refer to:
The liquid phase produced by the condensation of steam or any other gas
The product of a chemical condensation reaction, other than water
Natural-gas condensate, in the natural gas industry
Condensate (album), a 2011 album by The Original 7ven, the band formerly known as The Time
Quantum physics
Canonical quantization or vacuum expectation value, in quantum field theory
Bose–Einstein condensate, a substance which occurs at very low temperatures in a system of bosons
Fermionic condensate, a substance which occurs at very low temperatures in a system of fermions
Gluon condensate, a non-perturbative property of the QCD vacuum
Theoretical states
Color-glass condensate, an extreme type of matter theorized to exist in atomic nuclei traveling near the speed of light
Top quark condensate, an alternative theory to the Standard Model
See also
Biomolecular condensate
|
https://en.wikipedia.org/wiki/Paul%20Seymour%20%28mathematician%29
|
Paul D. Seymour (born 26 July 1950) is a British mathematician known for his work in discrete mathematics, especially graph theory. He (with others) was responsible for important progress on regular matroids and totally unimodular matrices, the four colour theorem, linkless embeddings, graph minors and structure, the perfect graph conjecture, the Hadwiger conjecture, claw-free graphs, χ-boundedness, and the Erdős–Hajnal conjecture. Many of his recent papers are available from his website.
Seymour is currently the Albert Baldwin Dod Professor of Mathematics at Princeton University. He won a Sloan Fellowship in 1983, and the Ostrowski Prize in 2003; and (sometimes with others) won the Fulkerson Prize in 1979, 1994, 2006 and 2009, and the Pólya Prize in 1983 and 2004. He received an honorary doctorate from the University of Waterloo in 2008, one from the Technical University of Denmark in 2013, and one from the École normale supérieure de Lyon in 2022. He was an invited speaker in the 1986 International Congress of Mathematicians and a plenary speaker in the 1994 International Congress of Mathematicians. He became a Fellow of the Royal Society in 2022.
Early life
Seymour was born in Plymouth, Devon, England. He was a day student at Plymouth College, and then studied at Exeter College, Oxford, gaining a BA degree in 1971, and D.Phil in 1975.
Career
From 1974 to 1976 he was a college research fellow at University College of Swansea, and then returned to Oxford for 1976–1980 a
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https://en.wikipedia.org/wiki/Series%20expansion
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In mathematics, a series expansion is a technique that expresses a function as an infinite sum, or series, of simpler functions. It is a method for calculating a function that cannot be expressed by just elementary operators (addition, subtraction, multiplication and division).
The resulting so-called series often can be limited to a finite number of terms, thus yielding an approximation of the function. The fewer terms of the sequence are used, the simpler this approximation will be. Often, the resulting inaccuracy (i.e., the partial sum of the omitted terms) can be described by an equation involving Big O notation (see also asymptotic expansion). The series expansion on an open interval will also be an approximation for non-analytic functions.
Types of series expansions
There are several kinds of series expansions, listed below.
Taylor series
A Taylor series is a power series based on a function's derivatives at a single point. More specifically, if a function is infinitely differentiable around a point , then the Taylor series of f around this point is given by
under the convention . The Maclaurin series of f is its Taylor series about .
Laurent series
A Laurent series is a generalization of the Taylor series, allowing terms with negative exponents; it takes the form and converges in an annulus. In particular, a Laurent series can be used to examine the behavior of a complex function near a singularity by considering the series expansion on an annulus centered
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https://en.wikipedia.org/wiki/Hyperbolic%20partial%20differential%20equation
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In mathematics, a hyperbolic partial differential equation of order is a partial differential equation (PDE) that, roughly speaking, has a well-posed initial value problem for the first derivatives. More precisely, the Cauchy problem can be locally solved for arbitrary initial data along any non-characteristic hypersurface. Many of the equations of mechanics are hyperbolic, and so the study of hyperbolic equations is of substantial contemporary interest. The model hyperbolic equation is the wave equation. In one spatial dimension, this is
The equation has the property that, if and its first time derivative are arbitrarily specified initial data on the line (with sufficient smoothness properties), then there exists a solution for all time .
The solutions of hyperbolic equations are "wave-like". If a disturbance is made in the initial data of a hyperbolic differential equation, then not every point of space feels the disturbance at once. Relative to a fixed time coordinate, disturbances have a finite propagation speed. They travel along the characteristics of the equation. This feature qualitatively distinguishes hyperbolic equations from elliptic partial differential equations and parabolic partial differential equations. A perturbation of the initial (or boundary) data of an elliptic or parabolic equation is felt at once by essentially all points in the domain.
Although the definition of hyperbolicity is fundamentally a qualitative one, there are precise criteria t
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https://en.wikipedia.org/wiki/Variadic%20function
|
In mathematics and in computer programming, a variadic function is a function of indefinite arity, i.e., one which accepts a variable number of arguments. Support for variadic functions differs widely among programming languages.
The term variadic is a neologism, dating back to 1936–1937. The term was not widely used until the 1970s.
Overview
There are many mathematical and logical operations that come across naturally as variadic functions. For instance, the summing of numbers or the concatenation of strings or other sequences are operations that can be thought of as applicable to any number of operands (even though formally in these cases the associative property is applied).
Another operation that has been implemented as a variadic function in many languages is output formatting. The C function and the Common Lisp function are two such examples. Both take one argument that specifies the formatting of the output, and any number of arguments that provide the values to be formatted.
Variadic functions can expose type-safety problems in some languages. For instance, C's , if used incautiously, can give rise to a class of security holes known as format string attacks. The attack is possible because the language support for variadic functions is not type-safe: it permits the function to attempt to pop more arguments off the stack than were placed there, corrupting the stack and leading to unexpected behavior. As a consequence of this, the CERT Coordination Center consider
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https://en.wikipedia.org/wiki/Incidence%20geometry
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In mathematics, incidence geometry is the study of incidence structures. A geometric structure such as the Euclidean plane is a complicated object that involves concepts such as length, angles, continuity, betweenness, and incidence. An incidence structure is what is obtained when all other concepts are removed and all that remains is the data about which points lie on which lines. Even with this severe limitation, theorems can be proved and interesting facts emerge concerning this structure. Such fundamental results remain valid when additional concepts are added to form a richer geometry. It sometimes happens that authors blur the distinction between a study and the objects of that study, so it is not surprising to find that some authors refer to incidence structures as incidence geometries.
Incidence structures arise naturally and have been studied in various areas of mathematics. Consequently, there are different terminologies to describe these objects. In graph theory they are called hypergraphs, and in combinatorial design theory they are called block designs. Besides the difference in terminology, each area approaches the subject differently and is interested in questions about these objects relevant to that discipline. Using geometric language, as is done in incidence geometry, shapes the topics and examples that are normally presented. It is, however, possible to translate the results from one discipline into the terminology of another, but this often leads to awkwa
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https://en.wikipedia.org/wiki/Fundamenta%20Mathematicae
|
Fundamenta Mathematicae is a peer-reviewed scientific journal of mathematics with a special focus on the foundations of mathematics, concentrating on set theory, mathematical logic, topology and its interactions with algebra, and dynamical systems.
The first specialized journal in the field of mathematics, originally it covered only topology, set theory, and foundations of mathematics. It is published by the Mathematics Institute of the Polish Academy of Sciences.
History
The journal was conceived by Zygmunt Janiszewski as a means to foster mathematical research in Poland. Janiszewski posited that, to achieve its goal, the journal should not compel Polish mathematicians to submit articles written exclusively in Polish, and should be devoted only to a specialized topic in mathematics; Fundamenta Mathematicae thus became the first specialized journal in the field of mathematics.
Despite Janiszewski having, in a 1918 article, given the initial impetus for the creation of the journal, he did not live long enough to see the first issue published, in Warsaw, as he died on 3 January 1920. Wacław Sierpiński and Stefan Mazurkiewicz took over as editors-in-chief. Soon after its launch, the founding editors were joined by Kazimierz Kuratowski and, later, by Karol Borsuk.
Abstracting and indexing
The journal is abstracted and indexed in the Science Citation Index Expanded, Scopus, and Zentralblatt MATH. According to the Journal Citation Reports, the journal has a 2016 impact facto
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https://en.wikipedia.org/wiki/Placodus
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Placodus (meaning 'flat tooth') was a genus of marine reptiles belonging to the order Placodontia, which swam in the shallow seas of the middle Triassic period (c. 240 million years ago). Fossils of Placodus have been found in Central Europe (Germany, France, Poland) and China.
Palaeobiology
Placodus had a stocky body with a long tail, and reached a total length of . It had a short neck, and a heavy skull. They were specialized for a durophagous diet of shellfish, such as bivalves. Chisel-like incisors protruded from the anterior margin of the snout, and were probably used to pluck hard-shelled benthic prey from the substrate. The back teeth were broad and flattened, and would have helped to crush the prey. Before the animals' anatomy was known, they were regarded as fishes' teeth. Similar smaller teeth were present on the palatine bones.
Placodus and its relatives were not as well-adapted to aquatic life as some later reptile groups, like the closely related plesiosaurs. Their flattened tails and short legs, which probably ended in webbed feet, would have been their main means of propulsion in the water.
The parietal eye on top of the head assisted the animal with orientation, rather than its vision, and its presence is regarded as a primitive characteristic.
The vertebral processes of Placodus dove-tailed into each other and were firmly connected, so that the trunk was rigid. The abdomen was covered with a special armor formed of the bent, right-angled abdominal rib
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https://en.wikipedia.org/wiki/Cofinal
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Cofinal may refer to:
Cofinal (mathematics), the property of a subset B of a preordered set A such that for every element of A there is a "larger element" in B
Cofinality (mathematics), the least cardinality of a cofinal subset in this sense
Cofinal (music), a part of some Gregorian chants
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https://en.wikipedia.org/wiki/Optimal%20asymmetric%20encryption%20padding
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In cryptography, Optimal Asymmetric Encryption Padding (OAEP) is a padding scheme often used together with RSA encryption. OAEP was introduced by Bellare and Rogaway, and subsequently standardized in PKCS#1 v2 and RFC 2437.
The OAEP algorithm is a form of Feistel network which uses a pair of random oracles G and H to process the plaintext prior to asymmetric encryption. When combined with any secure trapdoor one-way permutation , this processing is proved in the random oracle model to result in a combined scheme which is semantically secure under chosen plaintext attack (IND-CPA). When implemented with certain trapdoor permutations (e.g., RSA), OAEP is also proven to be secure against chosen ciphertext attack. OAEP can be used to build an all-or-nothing transform.
OAEP satisfies the following two goals:
Add an element of randomness which can be used to convert a deterministic encryption scheme (e.g., traditional RSA) into a probabilistic scheme.
Prevent partial decryption of ciphertexts (or other information leakage) by ensuring that an adversary cannot recover any portion of the plaintext without being able to invert the trapdoor one-way permutation .
The original version of OAEP (Bellare/Rogaway, 1994) showed a form of "plaintext awareness" (which they claimed implies security against chosen ciphertext attack) in the random oracle model when OAEP is used with any trapdoor permutation. Subsequent results contradicted this claim, showing that OAEP was only IND-CCA1 se
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https://en.wikipedia.org/wiki/Decade%20Volcanoes
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The Decade Volcanoes are 16 volcanoes identified by the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) as being worthy of particular study in light of their history of large, destructive eruptions and proximity to densely populated areas. The Decade Volcanoes project encourages studies and public-awareness activities at these volcanoes, with the aim of achieving a better understanding of the volcanoes and the dangers they present, and thus being able to reduce the severity of natural disasters.
They are named Decade Volcanoes because the project was initiated in the 1990s as part of the United Nations–sponsored International Decade for Natural Disaster Reduction.
A volcano may be designated a Decade Volcano if it exhibits more than one volcanic hazard (people living near the Decade Volcanoes may experience tephra fall, pyroclastic flows, lava flows, lahars, volcanic edifice instability and lava dome collapse); shows recent geological activity; is located in a densely populated area (eruptions at any of the Decade Volcanoes may threaten tens or hundreds of thousands of people, and therefore mitigating eruption hazards at these volcanoes is crucial); is politically and physically accessible for study; and there is local support for the work.
Aims of the program
The general approach of Decade Volcano projects has been to convene a planning workshop, identify the major strengths and weaknesses of risk mitigation at each volcano, and t
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https://en.wikipedia.org/wiki/Physics%20First
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Physics First is an educational program in the United States, that teaches a basic physics course in the ninth grade (usually 14-year-olds), rather than the biology course which is more standard in public schools. This course relies on the limited math skills that the students have from pre-algebra and algebra I. With these skills students study a broad subset of the introductory physics canon with an emphasis on topics which can be experienced kinesthetically or without deep mathematical reasoning. Furthermore, teaching physics first is better suited for English Language Learners, who would be overwhelmed by the substantial vocabulary requirements of Biology.
Physics First began as an organized movement among educators around 1990, and has been slowly catching on throughout the United States. The most prominent movement championing Physics First is Leon Lederman's ARISE (American Renaissance in Science Education).
Many proponents of Physics First argue that turning this order around lays the foundations for better understanding of chemistry, which in turn will lead to more comprehension of biology. Due to the tangible nature of most introductory physics experiments, Physics First also lends itself well to an introduction to inquiry-based science education, where students are encouraged to probe the workings of the world in which they live.
The majority of high schools which have implemented "physics first" do so by way of offering two separate classes, at two separa
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https://en.wikipedia.org/wiki/Reentrant%20mutex
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In computer science, the reentrant mutex (recursive mutex, recursive lock) is a particular type of mutual exclusion (mutex) device that may be locked multiple times by the same process/thread, without causing a deadlock.
While any attempt to perform the "lock" operation on an ordinary mutex (lock) would either fail or block when the mutex is already locked, on a recursive mutex this operation will succeed if and only if the locking thread is the one that already holds the lock. Typically, a recursive mutex tracks the number of times it has been locked, and requires equally many unlock operations to be performed before other threads may lock it.
Motivation
Recursive mutexes solve the problem of non-reentrancy with regular mutexes: if a function that takes a lock and executes a callback is itself called by the callback, deadlock ensues. In pseudocode, that is the following situation:
var m : Mutex // A non-recursive mutex, initially unlocked.
function lock_and_call(i : Integer)
m.lock()
callback(i)
m.unlock()
function callback(i : Integer)
if i > 0
lock_and_call(i - 1)
lock_and_call(1) // Invoking the function
Given these definitions, the function call will cause the following sequence of events:
— mutex locked
— because
— deadlock, because is already locked, so the executing thread will block, waiting for itself.
Replacing the mutex with a recursive one solves the problem, because the final will succeed without blockin
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https://en.wikipedia.org/wiki/Generalized%20function
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In mathematics, generalized functions are objects extending the notion of functions. There is more than one recognized theory, for example the theory of distributions. Generalized functions are especially useful in making discontinuous functions more like smooth functions, and describing discrete physical phenomena such as point charges. They are applied extensively, especially in physics and engineering.
A common feature of some of the approaches is that they build on operator aspects of everyday, numerical functions. The early history is connected with some ideas on operational calculus, and more contemporary developments in certain directions are closely related to ideas of Mikio Sato, on what he calls algebraic analysis. Important influences on the subject have been the technical requirements of theories of partial differential equations, and group representation theory.
Some early history
In the mathematics of the nineteenth century, aspects of generalized function theory appeared, for example in the definition of the Green's function, in the Laplace transform, and in Riemann's theory of trigonometric series, which were not necessarily the Fourier series of an integrable function. These were disconnected aspects of mathematical analysis at the time.
The intensive use of the Laplace transform in engineering led to the heuristic use of symbolic methods, called operational calculus. Since justifications were given that used divergent series, these methods had a bad rep
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https://en.wikipedia.org/wiki/Raju%20Ban%20Gaya%20Gentleman
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Raju Ban Gaya Gentleman () is a 1992 Indian Hindi-language romantic comedy-drama film directed by Aziz Mirza starring Shah Rukh Khan, Amrita Singh, Juhi Chawla and Nana Patekar. Khan plays Raju, a young Diploma Holder in Civil Engineering from Darjeeling who comes to Bombay hoping to become a successful engineer. The film emerged as a commercial success. The movie plot is loosely inspired by the 1987 movie The Secret of My Success and the Raj Kapoor classic Shree 420 (1955). The rights to this film are owned by Khan's Red Chillies Entertainment.
At the 38th Filmfare Awards, Raju Ban Gaya Gentleman won Best Screenplay (Mirza and Lalwani), in addition to a Best Supporting Actor nomination for Patekar.
Plot
Raj Mathur is a young Diploma holder in civil engineering from Darjeeling who comes to Bombay with only one ambition — to become a big engineer. In Bombay, he arrives in a lower-middle-class locality in search of a distant relative, only to discover he has left years before. He spends the night at a temple, where he meets a philosophical streetside performer Jai, who becomes a close friend and gives him a place to stay.
With no connections and no experience, he finds it hard to get a job in the city until a beautiful girl Renu, finds him a job as a trainee with the construction company where she works as a secretary to Chabbria. They eventually fall in love with each other.
As he becomes successful he gets the attention of Chhabria's daughter Sapna. They spend more and
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https://en.wikipedia.org/wiki/SECG
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In cryptography, the Standards for Efficient Cryptography Group (SECG) is an international consortium founded by Certicom in 1998. The group exists to develop commercial standards for efficient and interoperable cryptography based on elliptic curve cryptography (ECC).
Links and documents
SECG home page
SEC 1: Elliptic Curve Cryptography (Version 1.0 - Superseded by Version 2.0)
SEC 1: Elliptic Curve Cryptography (Version 2.0)
SEC 2: Recommended Elliptic Curve Domain Parameters (Version 1.0 - Superseded by Version 2.0
SEC 2: Recommended Elliptic Curve Domain Parameters (Version 2.0)
Certicom Patent Letter
See also
Elliptic curve cryptography
Cryptography organizations
Cryptography standards
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https://en.wikipedia.org/wiki/Bill%20T.%20Gross
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William T. Gross (born 1958) is an American businessman.
Early life
Gross grew up in Encino, California and graduated with a Bachelor of Science in mechanical engineering from the California Institute of Technology.
Career
He founded GNP Loudspeakers (now GNP Audio Video), an audio equipment manufacturer; Starship Video, a video arcade, GNP Development Inc., acquired by Lotus Software; Knowledge Adventure, an educational software company, later acquired by Cendant; and the business incubator Idealab in March, 1996, of which he serves as Chairman of the Board and Chief Executive Officer.
Gross serves on the boards of numerous companies. He is a member of the Board of Trustees of the California Institute of Technology and of the Art Center College of Design.
One company founded by Gross, GoTo.com, Inc., provided an Internet search engine which relied upon sponsored search results and pay-per-click advertisements. GoTo.com was later renamed Overture Services Inc. and was then acquired by Yahoo! to provide their Yahoo! Search Marketing products.
In 1996, Gross purchased the domain name answers.com, which was later sold to NetShepard and then to GuruNet.
In 2004, Gross created the SNAP search engine which introduced a new hyperlink previewer, Snap Shots.
In 2010, Gross founded and launched TweetUp, a search engine for Twitter that promotes the best tweeters on any topic. TweetUp was renamed to "PostUp" to reflect its inclusion of Facebook and LinkedIn status updates.
On
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https://en.wikipedia.org/wiki/L%C4%ABl%C4%81vat%C4%AB
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Līlāvatī is Indian mathematician Bhāskara II's treatise on mathematics, written in 1150 AD. It is the first volume of his main work, the Siddhānta Shiromani, alongside the Bijaganita, the Grahaganita and the Golādhyāya.
Name
His book on arithmetic is the source of interesting legends that assert that it was written for his daughter, Lilavati. Lilavati was Bhaskara II's daughter. Bhaskara II studied Lilavati's horoscope and predicted that she would remain both childless and unmarried. To avoid this fate, he ascertained an auspicious moment for his daughter's wedding and to alert his daughter at the correct time, he placed a cup with a small hole at the bottom of a vessel filled with water, arranged so that the cup would sink at the beginning of the propitious hour. He put the device in a room with a warning to Lilavati to not go near it. In her curiosity though, she went to look at the device and a pearl from her bridal dress accidentally dropped into it, thus upsetting it. The auspicious moment for the wedding thus passed unnoticed leaving a devastated Bhaskara II. It is then that he promised his daughter to write a book in her name, one that would remain till the end of time as a good name is akin to a second life.
Many of the problems are addressed to Līlāvatī herself who must have been a very bright young woman. For example "Oh Līlāvatī, intelligent girl, if you understand addition and subtraction, tell me the sum of the amounts 2, 5, 32, 193, 18, 10, and 100, as well a
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https://en.wikipedia.org/wiki/Ostrich%20algorithm
|
In computer science, the ostrich algorithm is a strategy of ignoring potential problems on the basis that they may be exceedingly rare. It is named after the ostrich effect which is defined as "to stick one's head in the sand and pretend there is no problem". It is used when it is more cost-effective to allow the problem to occur than to attempt its prevention.
Use with deadlocks
This approach may be used in dealing with deadlocks in concurrent programming if they are believed to be very rare and the cost of detection or prevention is high. A set of processes is deadlocked if each process in the set is waiting for an event that only another process in the set can cause.
The ostrich algorithm pretends there is no problem and is reasonable to use if deadlocks occur very rarely and the cost of their prevention would be high. The UNIX and Windows operating systems take this approach.
Although using the ostrich algorithm is one of the methods of dealing with deadlocks, other effective methods exist such as dynamic avoidance, banker's algorithm, detection and recovery, and prevention.
See also
Crash-only software
End-to-end principle
References
External links
Ostrich algorithm
Non-Hard Locking Read-Write Locker
Deadlock Basics + Modelling + Ostrich Algorithm
Concurrent algorithms
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https://en.wikipedia.org/wiki/August%20Herman%20Pfund
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August Herman Pfund (December 28, 1879 – January 4, 1949) was an American physicist, spectroscopist, and inventor.
Early life
Pfund was born in Madison, Wisconsin and attended Wisconsin public schools until his entry into the University of Wisconsin–Madison, where he earned a B.S. degree in physics and studied under Robert W. Wood.
Career
Both Wood and Pfund left Wisconsin for Johns Hopkins University in 1903. From 1903 to 1905 Pfund was a Carnegie research assistant and continued to work under Wood. In 1906 Pfund earned his Ph.D. in physics and was a Johnston scholar from 1907 to 1909. He remained at Hopkins for the remainder of his career, eventually becoming a full professor and later chair of the physics department. From 1943 to 1944 Pfund served as the president of the Optical Society of America.
Within the hydrogen spectral series Pfund discovered the fifth series, where an electron jumps up from or drops down to the fifth fundamental level. This Series is known as the "Pfund series". He also invented the Pfund telescope, which is a method for achieving a fixed telescope focal point regardless of where the telescope line of sight is positioned, and the Pfund sky compass, which arose from Pfund's studies of the polarization of scattered light from the sky in 1944, and which greatly helped transpolar flights by allowing the determination of the Sun's direction in twilight. Pfund is also noted for his work into the area of infrared gas analysis.
See also
Current and p
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https://en.wikipedia.org/wiki/Samuel%20S.%20Wagstaff%20Jr.
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Samuel Standfield Wagstaff Jr. (born 21 February 1945) is an American mathematician and computer scientist, whose research interests are in the areas of cryptography, parallel computation, and analysis of algorithms, especially number theoretic algorithms. He is currently a professor of computer science and mathematics at Purdue University who coordinates the Cunningham project, a project to factor numbers of the form bn ± 1, since 1983. He has authored/coauthored over 50 research papers and four books. He has an Erdős number of 1.
Wagstaff received his Bachelor of Science in 1966 from Massachusetts Institute of Technology. His doctoral dissertation was titled, On Infinite Matroids, PhD in 1970 from Cornell University.
Wagstaff was one of the founding faculty of Center for Education and Research in Information Assurance and Security (CERIAS) at Purdue, and its precursor, the Computer Operations, Audit, and Security Technology (COAST) Laboratory.
Selected publications
with John Brillhart, D. H. Lehmer, John L. Selfridge, Bryant Tuckerman: Factorization of bn ± 1, b = 2,3,5,6,7,10,11,12 up to high powers, American Mathematical Society, 1983, 3rd edition 2002 as electronic book, Online text
Cryptanalysis of number theoretic ciphers, CRC Press 2002
with Carlos J. Moreno: Sums of Squares of Integers, CRC Press 2005
The Joy of Factoring, Student Mathematical Library (American Mathematical Society) 2013
Wagstaff The Cunningham Project, Fields Institute, pdf file
=
Refer
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https://en.wikipedia.org/wiki/Nios%20II
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Nios II is a 32-bit embedded processor architecture designed specifically for the Altera family of field-programmable gate array (FPGA) integrated circuits. Nios II incorporates many enhancements over the original Nios architecture, making it more suitable for a wider range of embedded computing applications, from digital signal processing (DSP) to system-control.
Nios II is a successor to Altera's first configurable 16-bit embedded processor Nios, introduced in 2000.
Key features
Like the original Nios, the Nios II architecture is a RISC soft-core architecture which is implemented entirely in the programmable logic and memory blocks of Altera FPGAs. Unlike its predecessor it is a full 32-bit design:
32 general-purpose 32-bit registers,
Full 32-bit instruction set, data path, and address space,
Single-instruction 32 × 32 multiply and divide producing a 32-bit result.
The soft-core nature of the Nios II processor lets the system designer specify and generate a custom Nios II core, tailored for his or her specific application requirements. System designers can extend the Nios II's basic functionality by, for example, adding a predefined memory management unit, or defining custom instructions and custom peripherals.
Custom instructions
Similar to native Nios II instructions, user-defined instructions accept values from up to two 32-bit source registers and optionally write back a result to a 32-bit destination register. By using custom instructions, the system designers
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https://en.wikipedia.org/wiki/NASU%20Institute%20of%20Electrodynamics
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NASU Institute of Electrodynamics (IED) () is a Ukraine leading science institution in field of electrical engineering, thermal power (heat energy), and research of electrodynamics located in Kyiv, Ukraine as a part of the Ukrainian Academy of Sciences. It is well known for the prominent achievements in the field of computer science and electronics, made in early 1950s by Sergei Alekseyevich Lebedev.
The institute was established in 1947 on the basis of electrical engineering department of the NASU Energy Institute as the NASU Institute of Electrical Engineering. In 1963 it was renamed as the NASU Institute of Electrodynamics.
Notable achievements
MESM, an abbreviation for small electronic calculating system
Directors
1947 — 1952 Sergei Lebedev
1952 — 1959 Anatoliy Nesterenko
1959 — 1973 Oleksandr Milyakh
1973 — 2007 Anatoliy Shydlovskyi
2007 — Oleksandr Kyrylenko
External links
Official website
IED NASU. National Academy of Sciences of Ukraine
Research institutes in Kyiv
Computing in the Soviet Union
Research institutes in the Soviet Union
Institutes of the National Academy of Sciences of Ukraine
Computer science institutes in Ukraine
Energy research institutes
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https://en.wikipedia.org/wiki/1%2C10-Phenanthroline
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1,10-Phenanthroline (phen) is a heterocyclic organic compound. It is a white solid that is soluble in organic solvents. The 1,10 refer to the location of the nitrogen atoms that replace CH's in the hydrocarbon called phenanthrene.
Abbreviated "phen", it is used as a ligand in coordination chemistry, forming strong complexes with most metal ions. It is often sold as the monohydrate.
Synthesis
Phenanthroline may be prepared by two successive Skraup reactions of glycerol with o-phenylenediamine, catalyzed by sulfuric acid, and an oxidizing agent, traditionally aqueous arsenic acid or nitrobenzene. Dehydration of glycerol gives acrolein which condenses with the amine followed by a cyclization.
Coordination chemistry
In terms of its coordination properties, phenanthroline is similar to 2,2'-bipyridine (bipy) with the advantage that the two nitrogen donors are preorganized for chelation. Phenanthroline is a stronger base than bipy. According to one ligand ranking scale, phen is a weaker donor than bipy.
Several homoleptic complexes are known of the type [M(phen)3]2+. Particularly well studied is [Fe(phen)3]2+, called "ferroin." It can be used for the photometric determination of Fe(II). It is used as a redox indicator with standard potential +1.06 V. The reduced ferrous form has a deep red colour and the oxidised form is light-blue. The pink complex [Ni(phen)3]2+ has been resolved into its Δ and Λ isomers. The complex [Ru(phen)3]2+ is bioactive.
Copper(I) forms [Cu(ph
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https://en.wikipedia.org/wiki/Institute%20of%20Physical%20Chemistry%20of%20the%20Polish%20Academy%20of%20Sciences
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The Institute of Physical Chemistry of the Polish Academy of Sciences (Polish Instytut Chemii Fizycznej Polskiej Akademii Nauk) is one of numerous institutes belonging to the Polish Academy of Sciences. As its name suggests, the institute's primary research interests are in the field of physical chemistry. The institute is subdivided into departments, including the Department of Soft Condensed Matter and Fluids, the Department of Physical Chemistry of Supramolecular Complexes, the Department of Photochemistry and Spectroscopy and the Department of Quantum Theory of Solids and Molecules, this is also known as the PIPC.
External links
Institute of Physical Chemistry website
Institutes of the Polish Academy of Sciences
Chemistry organizations
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https://en.wikipedia.org/wiki/Weierstrass%20factorization%20theorem
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In mathematics, and particularly in the field of complex analysis, the Weierstrass factorization theorem asserts that every entire function can be represented as a (possibly infinite) product involving its zeroes. The theorem may be viewed as an extension of the fundamental theorem of algebra, which asserts that every polynomial may be factored into linear factors, one for each root.
The theorem, which is named for Karl Weierstrass, is closely related to a second result that every sequence tending to infinity has an associated entire function with zeroes at precisely the points of that sequence.
A generalization of the theorem extends it to meromorphic functions and allows one to consider a given meromorphic function as a product of three factors: terms depending on the function's zeros and poles, and an associated non-zero holomorphic function.
Motivation
It is clear that any finite set of points in the complex plane has an associated polynomial whose zeroes are precisely at the points of that set. The converse is a consequences of the fundamental theorem of algebra: any polynomial function in the complex plane has a factorization
where is a non-zero constant and is the set of zeroes of .
The two forms of the Weierstrass factorization theorem can be thought of as extensions of the above to entire functions. The necessity of additional terms in the product is demonstrated when one considers where the sequence is not finite. It can never define an entire funct
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https://en.wikipedia.org/wiki/Young%20symmetrizer
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In mathematics, a Young symmetrizer is an element of the group algebra of the symmetric group, constructed in such a way that, for the homomorphism from the group algebra to the endomorphisms of a vector space obtained from the action of on by permutation of indices, the image of the endomorphism determined by that element corresponds to an irreducible representation of the symmetric group over the complex numbers. A similar construction works over any field, and the resulting representations are called Specht modules. The Young symmetrizer is named after British mathematician Alfred Young.
Definition
Given a finite symmetric group Sn and specific Young tableau λ corresponding to a numbered partition of n, and consider the action of given by permuting the boxes of . Define two permutation subgroups and of Sn as follows:
and
Corresponding to these two subgroups, define two vectors in the group algebra as
and
where is the unit vector corresponding to g, and is the sign of the permutation. The product
is the Young symmetrizer corresponding to the Young tableau λ. Each Young symmetrizer corresponds to an irreducible representation of the symmetric group, and every irreducible representation can be obtained from a corresponding Young symmetrizer. (If we replace the complex numbers by more general fields the corresponding representations will not be irreducible in general.)
Construction
Let V be any vector space over the complex numbers. Consider then the tensor
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https://en.wikipedia.org/wiki/Fran%C3%A7ois-Xavier%20de%20Feller
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François-Xavier de Feller (18 August 1735 – 23 May 1802) was a Belgian author.
Biography
He was born in Brussels. In 1752 he entered a school of the Jesuits at Reims, where he manifested a great aptitude for mathematics and physical science. He commenced his novitiate two years afterwards, and in testimony of his admiration for the apostle of India added Xavier to his surname. On the expiry of his novitiate he became professor at Athénée de Luxembourg, and afterwards at Liège. In 1764 he was appointed to the professorship of theology at Tyrnau in Hungary, but in 1771 he returned to Belgium and continued to discharge his professorial duties at Liège till the suppression of the Jesuit Order in 1773.
The remainder of his life he devoted to study, travel and literature. On the invasion of Belgium by the French in 1794 he went to Paderborn, and remained there two years, after which he took up his residence at Ratisbon, where he died in 1802.
Feller's works exceed 120 volumes. In 1773 he published, under the assumed name Flexier de Reval (an anagram of "Xavier de Feller"), his Catéchisme philosophique; and his principal work Dictionnaire historique et littéraire (published in 1781 at Liège in volumes, and afterwards several times reprinted and continued down to 1848), appeared under the same name. Among his other works the most important are Cours de morale chrétienne et de littérature religieuse (Paris, 1826) and his Coup d'oeil sur le Congrès d'Ems (1787). The Journal historiq
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https://en.wikipedia.org/wiki/Dessin%20d%27enfant
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In mathematics, a dessin d'enfant is a type of graph embedding used to study Riemann surfaces and to provide combinatorial invariants for the action of the absolute Galois group of the rational numbers. The name of these embeddings is French for a "child's drawing"; its plural is either dessins d'enfant, "child's drawings", or dessins d'enfants, "children's drawings".
A dessin d'enfant is a graph, with its vertices colored alternately black and white, embedded in an oriented surface that, in many cases, is simply a plane. For the coloring to exist, the graph must be bipartite. The faces of the embedding are required be topological disks. The surface and the embedding may be described combinatorially using a rotation system, a cyclic order of the edges surrounding each vertex of the graph that describes the order in which the edges would be crossed by a path that travels clockwise on the surface in a small loop around the vertex.
Any dessin can provide the surface it is embedded in with a structure as a Riemann surface. It is natural to ask which Riemann surfaces arise in this way. The answer is provided by Belyi's theorem, which states that the Riemann surfaces that can be described by dessins are precisely those that can be defined as algebraic curves over the field of algebraic numbers. The absolute Galois group transforms these particular curves into each other, and thereby also transforms the underlying dessins.
For a more detailed treatment of this subject, see or .
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https://en.wikipedia.org/wiki/Physics%20processing%20unit
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A physics processing unit (PPU) is a dedicated microprocessor designed to handle the calculations of physics, especially in the physics engine of video games. It is an example of hardware acceleration.
Examples of calculations involving a PPU might include rigid body dynamics, soft body dynamics, collision detection, fluid dynamics, hair and clothing simulation, finite element analysis, and fracturing of objects.
The idea is having specialized processors offload time-consuming tasks from a computer's CPU, much like how a GPU performs graphics operations in the main CPU's place. The term was coined by Ageia to describe its PhysX chip. Several other technologies in the CPU-GPU spectrum have some features in common with it, although Ageia's product was the only complete one designed, marketed, supported, and placed within a system exclusively being a PPU.
History
An early academic PPU research project named SPARTA (Simulation of Physics on A Real-Time Architecture) was carried out at Penn State and University of Georgia. This was a simple FPGA based PPU that was limited to two dimensions. This project was extended into a considerably more advanced ASIC-based system named HELLAS.
February 2006 saw the release of the first dedicated PPU PhysX from Ageia (later merged into nVidia). The unit is most effective in accelerating particle systems, with only a small performance improvement measured for rigid body physics. The Ageia PPU is documented in depth in their US patent applic
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https://en.wikipedia.org/wiki/Interplanetary%20Scintillation%20Array
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The Interplanetary Scintillation Array (also known as the IPS Array or Pulsar Array) is a radio telescope that was built in 1967 at the Mullard Radio Astronomy Observatory, in Cambridge, United Kingdom, and was operated by the Cavendish Astrophysics Group. The instrument originally covered 4 acres (16,000 m²). It was enlarged to 9 acres in 1978, and was refurbished in 1989.
The array operates at a radio frequency of 81.5 MHz (3.7 m wavelength), and is made up of 4,096 dipole antennas in a phased array. Using 14 beams, it can map the northern sky in one day. The observatory's staff use sheep to keep grass away from the antennas because a lawn mower cannot fit in the spaces.
Antony Hewish designed the IPS Array to measure the high-frequency fluctuations of radio sources, originally for monitoring interplanetary scintillation. Hewish received a Nobel prize after the high time-resolution of the array allowed the detection of pulsars by Jocelyn Bell in 1967.
The IPS Array has more recently been used to track and help forecast interplanetary weather, and specifically to monitor the solar wind. It is now essentially retired, and has lost a significant fraction of its area.
References
Cavendish Laboratory
Radio telescopes
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https://en.wikipedia.org/wiki/The%20Causes%20of%20Evolution
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The Causes of Evolution is a 1932 book on evolution by J.B.S. Haldane (1990 edition ), based on a series of January 1931 lectures entitled "A Re-examination of Darwinism". It was influential in the founding of population genetics and the modern synthesis.
Chapters
It contains the following chapters:
Introduction
Variation within a Species
The Genetical Analysis of Interspecific Differences
Natural Selection
What is Fitness?
Conclusion
The book also contains an extensive appendix containing the majority of Haldane's mathematical treatment of the subject.
See also
Evolutionary biology
External links
Description by Princeton U Press
Contemporary review by R.A. Fisher
Review of the 1990 Princeton University reprint
1932 non-fiction books
Books about evolution
Modern synthesis (20th century)
Population genetics
Works by J. B. S. Haldane
1932 in biology
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https://en.wikipedia.org/wiki/Fr%C3%A9chet%20filter
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In mathematics, the Fréchet filter, also called the cofinite filter, on a set is a certain collection of subsets of (that is, it is a particular subset of the power set of ).
A subset of belongs to the Fréchet filter if and only if the complement of in is finite.
Any such set is said to be , which is why it is alternatively called the cofinite filter on .
The Fréchet filter is of interest in topology, where filters originated, and relates to order and lattice theory because a set's power set is a partially ordered set under set inclusion (more specifically, it forms a lattice).
The Fréchet filter is named after the French mathematician Maurice Fréchet (1878-1973), who worked in topology.
Definition
A subset of a set is said to be cofinite in if its complement in (that is, the set ) is finite.
If the empty set is allowed to be in a filter, the Fréchet filter on , denoted by is the set of all cofinite subsets of .
That is:
If is a finite set, then every cofinite subset of is necessarily not empty, so that in this case, it is not necessary to make the empty set assumption made before.
This makes a on the lattice the power set of with set inclusion, given that denotes the complement of a set in the following two conditions hold:
Intersection condition If two sets are finitely complemented in then so is their intersection, since and
Upper-set condition If a set is finitely complemented in then so are its supersets in .
Properties
If the base set
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https://en.wikipedia.org/wiki/Reuben%20Goodstein
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Reuben Louis Goodstein (15 December 1912 – 8 March 1985) was an English mathematician with a strong interest in the philosophy and teaching of mathematics.
Education
Goodstein was educated at St Paul's School in London. He received his Master's degree from Magdalene College, Cambridge. After this, he worked at the University of Reading but ultimately spent most of his academic career at the University of Leicester. He earned his PhD from the University of London in 1946 while still working in Reading.
Goodstein also studied under Ludwig Wittgenstein.
Research
He published many works on finitism and the reconstruction of analysis from a finitistic viewpoint, for example "Constructive Formalism. Essays on the foundations of mathematics." Goodstein's theorem was among the earliest examples of theorems found to be unprovable in Peano arithmetic but provable in stronger logical systems (such as second-order arithmetic). He also introduced a variant of the Ackermann function that is now known as the hyperoperation sequence, together with the naming convention now used for these operations (tetration, pentation, hexation, etc.).
Besides mathematical logic (in which he held the first professorial chair in the U.K.), mathematical analysis, and the philosophy of mathematics, Goodstein was keenly interested in the teaching of mathematics. From 1956 to 1962 he was editor of The Mathematical Gazette. In 1962 he was an invited speaker at the International Congress of Mathematicians (wi
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https://en.wikipedia.org/wiki/Mordechai%20Ben-Ari
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Mordechai (Moti) Ben-Ari () is a professor emeritus of computer science education at the Weizmann Institute of Science.
Ben-Ari has published numerous textbooks in computer science, developed software tools for teaching computer science, and written influential papers in computer science education. His primary focus has been on books and tools for learning theoretical concepts in computer science and mathematics, such as concurrency and mathematical logic.
In collaboration with the University of Joensuu (now part of the University of Eastern Finland) his group developed the Jeliot program animation system for teaching elementary computer science and programming.
He has collaborated with the École Polytechnique Fédérale de Lausanne on educational robotics using the Thymio robot.
Ben-Ari has published two books under the Springer Open Access program:
Elements of Robotics with Francesco Mondada.
Mathematical Surprises.
Ben-Ari received ACM SIGCSE Award for Outstanding Contributions for Computer Science Education in 2004, was named an ACM Distinguished Educator in 2009 and received the ACM Karl V. Karlstrom Award in 2019.
References
External links
Jeliot Program Animation System.
Repositories of pedagogical software and learning materials on GitHub.
Programming language researchers
Israeli computer scientists
Living people
Year of birth missing (living people)
Computer science educators
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https://en.wikipedia.org/wiki/Johny%20Joseph%20%28civil%20servant%29
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Johny Joseph (born 29 May 1949) is an Indian Administrative Service officer of 1972 batch. He graduated from Trivandrum Engineering College with a degree in Mechanical Engineering and served as commissioner of Brihanmumbai Municipal Corporation from 29 February 2004 to May 2007.
Work
Johny Joseph was the Maharashtra's Principal Secretary to the Chief Minister before the state government granted him the post of the civic chief of Mumbai. He was succeeded by Jairaj Phatak in May 2007. On 1 May 2007, he was appointed as Chief Secretary of Maharashtra.
Posts held in the Government
Chief Secretary Government of Maharashtra
Municipal commissioner of Brihanmumbai Municipal Corporation
Lokayukta
Personal life
Johny Joseph is married to Reena Joseph who is an active environmentalist and patron of several social causes.
References
1949 births
Living people
Syro-Malabar Catholics
Indian Administrative Service officers
Mumbai civic officials
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https://en.wikipedia.org/wiki/Land%C3%A9%20g-factor
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In physics, the Landé g-factor is a particular example of a g-factor, namely for an electron with both spin and orbital angular momenta. It is named after Alfred Landé, who first described it in 1921.
In atomic physics, the Landé g-factor is a multiplicative term appearing in the expression for the energy levels of an atom in a weak magnetic field. The quantum states of electrons in atomic orbitals are normally degenerate in energy, with these degenerate states all sharing the same angular momentum. When the atom is placed in a weak magnetic field, however, the degeneracy is lifted.
Description
The factor comes about during the calculation of the first-order perturbation in the energy of an atom when a weak uniform magnetic field (that is, weak in comparison to the system's internal magnetic field) is applied to the system. Formally we can write the factor as,
The orbital is equal to 1, and under the approximation , the above expression simplifies to
Here, J is the total electronic angular momentum, L is the orbital angular momentum, and S is the spin angular momentum. Because for electrons, one often sees this formula written with 3/4 in place of . The quantities gL and gS are other g-factors of an electron. For an atom, and for an atom, .
If we wish to know the g-factor for an atom with total atomic angular momentum (nucleus + electrons), such that the total atomic angular momentum quantum number can take values of , giving
Here is the Bohr magneton and is
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https://en.wikipedia.org/wiki/Evolution%20in%20Mendelian%20Populations
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"Evolution in Mendelian Populations" is a lengthy 1931 scientific paper on evolution by the American population geneticist Sewall Wright.
The paper was first published in Genetics volume 16, pages 97–159. In it, Wright outlines various concepts, including genetic drift, effective population size, and inbreeding.
A contemporary review by R.A. Fisher can be found here
Overview
Studiers of evolution such as Lamarck and those who postulated the inheritance of acquired characteristics (e.g. Theodor Eimer and Edward Drinker Cope) were concerned with heredity and sought a link between one generation to the next. Lamarck thought that bodily responses from one generation should be passed along to future generations, which Wright refers to as "direct evolution". Sewall Wright expresses that the birth of genetics stems from Mendelian inheritance principles and so "any theory of evolution" must also be based on Mendelian inheritance.
See also
Evolutionary biology
References
External links
Reprint from Genetics
Reprint in Electronic Scholarly Publishing
Evolutionary biology literature
Biology papers
1931 in biology
1931 documents
Works originally published in Genetics (journal)
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https://en.wikipedia.org/wiki/Neal%20Koblitz
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Neal I. Koblitz (born December 24, 1948) is a Professor of Mathematics at the University of Washington. He is also an adjunct professor with the Centre for Applied Cryptographic Research at the University of Waterloo. He is the creator of hyperelliptic curve cryptography and the independent co-creator of elliptic curve cryptography.
Biography
Koblitz received his B.A. in mathematics from Harvard University in 1969. While at Harvard, he was a Putnam Fellow in 1968. He received his Ph.D. from Princeton University in 1974 under the direction of Nick Katz. From 1975 to 1979 he was an instructor at Harvard University. In 1979 he began working at the University of Washington.
Koblitz's 1981 article "Mathematics as Propaganda" criticized the misuse of mathematics in the social sciences and helped motivate Serge Lang's successful challenge to the nomination of political scientist Samuel P. Huntington to the National Academy of Sciences. In The Mathematical Intelligencer, Koblitz, Steven Weintraub, and Saunders Mac Lane later criticized the arguments of Herbert A. Simon, who had attempted to defend Huntington's work.
He co-invented Elliptic-curve cryptography in 1985, with Victor S. Miller and for this was awarded the Levchin Prize in 2021.
With his wife Ann Hibner Koblitz, he in 1985 founded the Kovalevskaia Prize, to honor women scientists in developing countries. It was financed from the royalties of Ann Hibner Koblitz's 1983 biography of Sofia Kovalevskaia. Although the aw
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https://en.wikipedia.org/wiki/Yun%20Wang
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Yun Wang (born 1964) is a poet and cosmologist. She is originally from Gaoping, a small town near Zunyi, in Guizhou Province, China.
Professional work in astrophysics
Yun Wang received a bachelor's degree in physics from Tsinghua University in Beijing, after which she came to the United States and obtained her master's and doctorate (also in physics) from Carnegie Mellon University. A senior research scientist at California Institute of Technology since 2015, and a professor in the University of Oklahoma's department of physics and astronomy until 2017, she has published over 100 refereed papers, most recently specializing on probing the dark energy in the Universe, with particular attention to the use of supernovae and galaxy redshift surveys as cosmological probes, studies of the cosmic microwave background anisotropy, and the measurement of cosmological parameters.
Yun Wang has developed strategies for optimizing future surveys to probe dark energy, and created a mission concept for the NASA-DOE Joint Dark Energy Mission (JDEM), the Joint Efficient Dark-energy Investigation (JEDI), and served as the principal investigator of JEDI. The JEDI/JDEM mission concept illustrates the extraordinary efficiency achievable through innovative instrumentation, and the great scientific advantages of combining three independent observational methods (galaxy clustering, weak lensing, and supernovae) to probe dark energy. JEDI has significantly impacted the design of space missions to
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https://en.wikipedia.org/wiki/Unimodality
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In mathematics, unimodality means possessing a unique mode. More generally, unimodality means there is only a single highest value, somehow defined, of some mathematical object.
Unimodal probability distribution
In statistics, a unimodal probability distribution or unimodal distribution is a probability distribution which has a single peak. The term "mode" in this context refers to any peak of the distribution, not just to the strict definition of mode which is usual in statistics.
If there is a single mode, the distribution function is called "unimodal". If it has more modes it is "bimodal" (2), "trimodal" (3), etc., or in general, "multimodal". Figure 1 illustrates normal distributions, which are unimodal. Other examples of unimodal distributions include Cauchy distribution, Student's t-distribution, chi-squared distribution and exponential distribution. Among discrete distributions, the binomial distribution and Poisson distribution can be seen as unimodal, though for some parameters they can have two adjacent values with the same probability.
Figure 2 and Figure 3 illustrate bimodal distributions.
Other definitions
Other definitions of unimodality in distribution functions also exist.
In continuous distributions, unimodality can be defined through the behavior of the cumulative distribution function (cdf). If the cdf is convex for x < m and concave for x > m, then the distribution is unimodal, m being the mode. Note that under this definition the uniform distribu
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https://en.wikipedia.org/wiki/Giuseppe%20Occhialini
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Giuseppe Paolo Stanislao "Beppo" Occhialini ForMemRS (; 5 December 1907 – 30 December 1993) was an Italian physicist who contributed to the discovery of the pion or pi-meson decay in 1947 with César Lattes and Cecil Frank Powell, the latter winning the Nobel Prize in Physics for this work. At the time of this discovery, they were all working at the H. H. Wills Laboratory of the University of Bristol.
The X-ray satellite SAX was named BeppoSAX in his honour after its launch in 1996.
Biography
His father was the physicist Raffaele Augusto Occhialini (1878–1951), a pioneer in the fields of spectroscopy and electronics theory. Giuseppe Paolo Stanislao Occhialini graduated at Florence in 1929. In 1932, he collaborated in the discovery of the positron in cosmic rays at the Cavendish Laboratory of Cambridge, under the leadership of Patrick Blackett, using cloud chambers.
He returned in Italy in 1934, where he suffered from the political climate generated by fascism. Thus, from 1937 to 1944, following an invitation by Gleb Wataghin, he worked at the Institute of Physics of the University of São Paulo, in Brazil.
In 1944 he returned to England, working at the Wills Physics Laboratory in Bristol, where he studied cosmic rays.
In 1947, while in Bristol, he contributed to the discovery of the pion or pi-meson decay in collaboration with César Lattes, Cecil Frank Powell and Hugh Muirhead. The discovery was made using the technology of the tracks on specialized photographic emulsion
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https://en.wikipedia.org/wiki/Michelle%20Alves
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Michelle Kristine da Silva Alves (born September 19, 1978) is a Brazilian model.
Biography
She was born in Londrina, Paraná, Brazil, as the daughter of a lawyer (mother) and an engineer (father). Alves was a student in civil engineering at Brazil's Londrina State University prior to moving to São Paulo, where she pursued modeling. She describes herself as "always a good student" and "Almost a nerd." She is also a polyglot, fluent in Portuguese, Italian, French and English. Alves is currently living in Los Angeles, California.
Career
She was featured in the 2002 and 2003 editions of the Sports Illustrated Swimsuit Issue, appeared in two editions of the Victoria's Secret Fashion Show, and was also featured in their catalogs and their book celebrating the company's 10th anniversary, entitled Sexy.
Alves has signed contracts with Valentino, Christian Dior, Escada, Ralph Lauren, Missoni, Miss Sixty, Michael Kors, GAP, Emporio Armani, Michael Kors Swimwear, AKRIS and holds a deal with Yves Saint Laurent for their fragrance Cinéma's campaign. She has worked with photographers such as Steven Meisel, Patrick Demarchelier, Bruce Weber, Gilles Bensimon, Mario Sorrenti, Nick Knight, Steven Klein, Phil Poynter, Walter Chin, Inez van Lamsweerde and Vinoodh Matadin and Richard Avedon.
Alves was featured on more than 100 covers of major fashion magazines, including international editions of Vogue, Elle, Marie Claire, French, Esquire, L'Officiel, Harper's Bazaar, Amica and Glamour.
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https://en.wikipedia.org/wiki/Geoffrey%20Perry
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Geoffrey E. Perry MBE (4 August 1927, Braintree, Essex – 18 January 2000, Bude) was a physics teacher at Kettering Grammar School, Northamptonshire, England who, together with his colleague Derek Slater, and students, deduced the existence of the previously-secret Plesetsk Cosmodrome in 1966 by analyzing the orbit of the Kosmos 112 satellite. The New York Times published his discovery shortly before Christmas in 1966.
Perry and his students (who formed the Kettering Group along with some other volunteers worldwide) continued their satellite tracking work for a number of years, using only inexpensive shortwave radio equipment and painstakingly using the Doppler effect to deduce the satellites' orbits. They were often able to deduce what various Soviet satellites were being used for, based on their telemetry. This information was likely already known by Western intelligence agencies, although it was classified, meaning that the Kettering Group played an important role in making information about the Soviet space programme publicly available.
Perry received an MBE in 1973, in the New Year Honours List. In 1974, he received the Jackson-Gwilt Medal of the Royal Astronomical Society. After retiring from teaching in 1984 he worked as a space analyst for the ITN television network. He was married to Jean, and had a daughter, Isabel.
References
External links
Satellite Tracking Group Members
New York Times obituary
Obituary
Obituary
Satellite tracking group
1927 births
200
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https://en.wikipedia.org/wiki/Restriction%20%28mathematics%29
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In mathematics, the restriction of a function is a new function, denoted or obtained by choosing a smaller domain for the original function
The function is then said to extend
Formal definition
Let be a function from a set to a set If a set is a subset of then the restriction of to is the function
given by for Informally, the restriction of to is the same function as but is only defined on .
If the function is thought of as a relation on the Cartesian product then the restriction of to can be represented by its graph where the pairs represent ordered pairs in the graph
Extensions
A function is said to be an of another function if whenever is in the domain of then is also in the domain of and
That is, if and
A (respectively, , etc.) of a function is an extension of that is also a linear map (respectively, a continuous map, etc.).
Examples
The restriction of the non-injective function to the domain is the injection
The factorial function is the restriction of the gamma function to the positive integers, with the argument shifted by one:
Properties of restrictions
Restricting a function to its entire domain gives back the original function, that is,
Restricting a function twice is the same as restricting it once, that is, if then
The restriction of the identity function on a set to a subset of is just the inclusion map from into
The restriction of a continuous function is continuous.
Applications
Inverse func
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https://en.wikipedia.org/wiki/White%20Light%20%28novel%29
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White Light is a work of science fiction by Rudy Rucker published in 1980 by Virgin Books in the UK and Ace Books in the US. It was written while Rucker was teaching mathematics at the University of Heidelberg from 1978 to 1980, at roughly the same time he was working on the non-fiction book Infinity and the Mind.
On one level, the book is an exploration of the mathematics of infinity through fiction, in much the same way the novel Flatland: A Romance of Many Dimensions explored the concept of multiple dimensions. More specifically, White Light uses an imaginary universe to elucidate the set theory concept of aleph numbers, which are more or less the idea that some infinities are bigger than others.
Plot summary
The book is the story of Felix Rayman, a down-and-out mathematics teacher at SUCAS (a state college in New York, a play on SUNY) with a troubled family life and dead-in-the-water career. In the fictional town of Bernho (Geneseo), he begins experimenting with lucid dreaming—aided by "fuzz weed" (marijuana)—hoping to gain insight into Cantor's continuum hypothesis.
During an out-of-body experience, Felix loses his physical body and nearly falls victim to the Devil, who hunts the Earth for souls like his to take to Hell; Felix calls upon Jesus, who saves him. Jesus asks Felix to do him a favor: to take a restless ghost named Kathy to a place called "Cimön", and bring her to God/Absolute Infinite, which can be found there.
Cimön is permeated with the notion of infini
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https://en.wikipedia.org/wiki/Kleinian%20model
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In mathematics, a Kleinian model is a model of a three-dimensional hyperbolic manifold N by the quotient space where is a discrete subgroup of PSL(2,C). Here, the subgroup , a Kleinian group, is defined so that it is isomorphic to the fundamental group of the surface N. Many authors use the terms Kleinian group and Kleinian model interchangeably, letting one stand for the other. The concept is named after Felix Klein.
Many properties of Kleinian models are in direct analogy to those of Fuchsian models; however, overall, the theory is less well developed. A number of unsolved conjectures on Kleinian models are the analogs to theorems on Fuchsian models.
See also
Hyperbolic 3-manifold
References
Hyperbolic geometry
Kleinian groups
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