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https://en.wikipedia.org/wiki/Octagram | In geometry, an octagram is an eight-angled star polygon.
The name octagram combine a Greek numeral prefix, octa-, with the Greek suffix -gram. The -gram suffix derives from γραμμή (grammḗ) meaning "line".
Detail
In general, an octagram is any self-intersecting octagon (8-sided polygon).
The regular octagram is labeled by the Schläfli symbol {8/3}, which means an 8-sided star, connected by every third point.
Variations
These variations have a lower dihedral, Dih4, symmetry:
The symbol Rub el Hizb is a Unicode glyph ۞ at U+06DE.
As a quasitruncated square
Deeper truncations of the square can produce isogonal (vertex-transitive) intermediate star polygon forms with equal spaced vertices and two edge lengths. A truncated square is an octagon, t{4}={8}. A quasitruncated square, inverted as {4/3}, is an octagram, t{4/3}={8/3}.
The uniform star polyhedron stellated truncated hexahedron, t'{4,3}=t{4/3,3} has octagram faces constructed from the cube in this way. It may be considered for this reason as a three-dimensional analogue of the octagram.
Another three-dimensional version of the octagram is the nonconvex great rhombicuboctahedron (quasirhombicuboctahedron), which can be thought of as a quasicantellated (quasiexpanded) cube, t0,2{4/3,3}.
Star polygon compounds
There are two regular octagrammic star figures (compounds) of the form {8/k}, the first constructed as two squares {8/2}=2{4}, and second as four degenerate digons, {8/4}=4{2}. There are other isogonal and isotoxal compounds including rectangular and rhombic forms.
{8/2} or 2{4}, like Coxeter diagrams + , can be seen as the 2D equivalent of the 3D compound of cube and octahedron, + , 4D compound of tesseract and 16-cell, + and 5D compound of 5-cube and 5-orthoplex; that is, the compound of a n-cube and cross-polytope in their respective dual positions.
Other presentations of an octagonal star
An octagonal star can be seen as a concave hexadecagon, with internal intersecting geometry erased. |
https://en.wikipedia.org/wiki/Retransmission%20%28data%20networks%29 | Retransmission, essentially identical with automatic repeat request (ARQ), is the resending of packets which have been either damaged or lost. Retransmission is one of the basic mechanisms used by protocols operating over a packet switched computer network to provide reliable communication (such as that provided by a reliable byte stream, for example TCP).
Such networks are usually "unreliable", meaning they offer no guarantees that they will not delay, damage, or lose packets, or deliver them out of order. Protocols which provide reliable communication over such networks use a combination of acknowledgments (i.e. an explicit receipt from the destination of the data), retransmission of missing or damaged packets (usually initiated by a time-out), and checksums to provide that reliability.
Acknowledgment
There are several forms of acknowledgement which can be used alone or together in networking protocols:
Positive Acknowledgement: the receiver explicitly notifies the sender which packets, messages, or segments were received correctly. Positive Acknowledgement therefore also implicitly informs the sender which packets were not received and provides detail on packets which need to be retransmitted.
Negative Acknowledgment (NACK): the receiver explicitly notifies the sender which packets, messages, or segments were received incorrectly and thus may need to be retransmitted (RFC 4077).
Selective Acknowledgment (SACK): the receiver explicitly lists which packets, messages, or segments in a stream are acknowledged (either negatively or positively). Positive selective acknowledgment is an option in TCP (RFC 2018) that is useful in Satellite Internet access (RFC 2488).
Cumulative Acknowledgment: the receiver acknowledges that it correctly received a packet, message, or segment in a stream which implicitly informs the sender that the previous packets were received correctly. TCP uses cumulative acknowledgment with its TCP sliding window.
Retransmission
Retransmiss |
https://en.wikipedia.org/wiki/Mondrian%20OLAP%20server | Mondrian is an open source OLAP (online analytical processing) server, written in Java. It supports the MDX
(multidimensional expressions) query language and the XML for Analysis and olap4j interface specifications. It reads from SQL and other data sources and aggregates data in a memory cache.
Mondrian is used for:
High performance, interactive analysis of large or small volumes of information
Dimensional exploration of data, for example analyzing sales by product line, by region, by time period
Parsing the MDX language into Structured Query Language (SQL) to retrieve answers to dimensional queries
High-speed queries through the use of aggregate tables in the RDBMS
Advanced calculations using the calculation expressions of the MDX language
Mondrian History
The first public release of Mondrian was on August 9, 2002.
See also
Business intelligence
Comparison of OLAP servers
Online analytical processing
Software using the Eclipse license |
https://en.wikipedia.org/wiki/Godwin%20Plots | The Godwin Plots are one of the world's longest running science experiments. They can be found at Wicken Fen nature reserve, Cambridgeshire, England.
Five experimental areas of vegetation were established in the 1927 by Prof. Sir Harry Godwin. The first plot is never cut. The second is cut every four years, the next every three years and so on. Godwin completed his experiment in 1940, and the plots were left uncut, but the same plots were restored in 1954, and have been managed in accordance with Godwin's original methodology since that time.
The cutting is undertaken in November/December every year. This management has, over many years, produced different vegetation patterns. Godwin used the experiment to demonstrate that management alone can change plant communities - an idea which is almost universally accepted today, but was quite radical in the early 20th century. Because of this work, the Plots, or Wicken Fen generally, are sometimes referred to as 'The birthplace of modern ecology'.
See also
Long-term experiment |
https://en.wikipedia.org/wiki/FORMAC |
FORMAC, the FORmula MAnipulation Compiler, was the first computer algebra system to have significant use. It was developed by Jean E. Sammet and her team, as an extension of FORTRAN IV. The compiler was implemented as a preprocessor taking the FORMAC program and converting it to a FORTRAN IV program which was in turn compiled without further user intervention.
Initial development started in 1962 and was complete by April 1964. In November it was released to IBM customers.
FORMAC supported computation, manipulation, and use of symbolic expressions. In addition it supported rational arithmetic.
See also
ALTRAN |
https://en.wikipedia.org/wiki/Java%20Modeling%20Language | The Java Modeling Language (JML) is a specification language for Java programs, using Hoare style pre- and postconditions and invariants, that follows the design by contract paradigm. Specifications are written as Java annotation comments to the source files, which hence can be compiled with any Java compiler.
Various verification tools, such as a runtime assertion checker and the Extended Static Checker (ESC/Java) aid development.
Overview
JML is a behavioural interface specification language for Java modules. JML provides semantics to formally describe the behavior of a Java module, preventing ambiguity with regard to the module designers' intentions. JML inherits ideas from Eiffel, Larch and the Refinement Calculus, with the goal of providing rigorous formal semantics while still being accessible to any Java programmer. Various tools are available that make use of JML's behavioral specifications. Because specifications can be written as annotations in Java program files, or stored in separate specification files, Java modules with JML specifications can be compiled unchanged with any Java compiler.
Syntax
JML specifications are added to Java code in the form of annotations in comments. Java comments are interpreted as JML annotations when they begin with an @ sign. That is, comments of the form
//@ <JML specification>
or
/*@ <JML specification> @*/
Basic JML syntax provides the following keywords
requires Defines a precondition on the method that follows.
ensures Defines a postcondition on the method that follows.
signals Defines a postcondition for when a given Exception is thrown by the method that follows.
signals_only Defines what exceptions may be thrown when the given precondition holds.
assignable Defines which fields are allowed to be assigned to by the method that follows.
pure Declares a method to be side effect free (like assignable \nothing but can also throw exceptions). Furthermore, a pure method is supposed to always either |
https://en.wikipedia.org/wiki/Community%20Z%20Tools | The Community Z Tools (CZT) initiative is based around a SourceForge project to build a set of tools for the Z notation, a formal method useful in software engineering. Tools include support for editing, typechecking and animating Z specifications. There is some support for extensions such as Object-Z and TCOZ. The tools are built using the Java programming language.
CZT was proposed by Andrew Martin of Oxford University in 2001. |
https://en.wikipedia.org/wiki/Michael%20J.%20C.%20Gordon | Michael John Caldwell Gordon (28 February 1948 – 22 August 2017) was a British computer scientist.
Life
Mike Gordon was born in Ripon, Yorkshire, England. He attended Dartington Hall School and Bedales School. In 1966, he was accepted to study engineering at Gonville and Caius College, University of Cambridge, but transferred to mathematics. During his studies, in 1969 he worked at the National Physical Laboratory in London during the summer, gaining his first exposure to computers.
Gordon studied for his PhD degree at University of Edinburgh, supervised by Rod Burstall, finishing in 1973 with a thesis entitled Evaluation and Denotation of Pure LISP Programs. He was invited to Stanford University in California by John McCarthy, the inventor of LISP, to work in his Artificial Intelligence Laboratory there. Gordon worked at the Cambridge University Computer Laboratory from 1981, initially as a lecturer, promoted to Reader in 1988 and Professor in 1996.
He was elected a Fellow of the Royal Society in 1994, and in 2008 a two-day research meeting on Tools and Techniques for Verification of System Infrastructure was held there in honour of his 60th birthday.
Mike Gordon was married to Avra Cohn, a PhD student of Robin Milner at the University of Edinburgh, and they undertook research together.
He died in Cambridge after a brief illness and is survived by his wife and two sons.
Work
Gordon led the development of the HOL theorem prover. The HOL system is an environment for interactive theorem proving in a higher-order logic. Its most outstanding feature is its high degree of programmability through the meta-language ML. The system has a wide variety of uses, from formalising pure mathematics to verification of industrial hardware.
There has been a series of international conferences on the HOL system, TPHOLs. The first three were informal users' meetings with no published proceedings. The tradition now is for an annual conference in a continent different from the lo |
https://en.wikipedia.org/wiki/Bokosuka%20Wars | is a 1983 action-strategy role-playing video game developed by Kōji Sumii (住井浩司) and released by ASCII for the Sharp X1 computer, followed by ports to the MSX, FM-7, NEC PC-6001, NEC PC-8801 and NEC PC-9801 computer platforms, as well as an altered version released for the Family Computer console and later the Virtual Console service. It revolves around a leader who must lead an army in phalanx formation across a battlefield in real-time against overwhelming enemy forces while freeing and recruiting soldiers along the way, with each unit able to gain experience and level up through battle. The player must make sure that the leader stays alive, until the army reaches the enemy castle to defeat the leader of the opposing forces.
The game was responsible for laying the foundations for the tactical role-playing game genre, or the "simulation RPG" genre as it is known in Japan, with its blend of role-playing and strategy game elements. The game has also variously been described as an early example of an action role-playing game, an early prototype real-time strategy game, and a unique reverse tower defense game. In its time, the game was considered a major success in Japan.
Release
Originally developed in 1983 for the Sharp X1 computer, it won ASCII Entertainment's first "Software Contest" and was sold boxed by them that year. An MSX port was then released in 1984, followed in 1985 by versions for the S1, PC-6000mkII, PC-8801, PC-9801, FM-7 and the Family Computer (the latter released on December 14, 1985).
LOGiN Magazine's November 1984 issue featured a sequel for the X1 entitled New Bokosuka Wars with the source code included. With all-new enemy characters and redesigned items and traps, the level of difficulty became more balanced. It was also included in Tape Login Magazine's November 1984 issue, but never sold in any other form.
The PC-8801 version used to be sold as a download from Enterbrain and was ported for the i-Mode service in 2004. The Famicom version wa |
https://en.wikipedia.org/wiki/Pulsed-field%20gel%20electrophoresis | Pulsed-field gel electrophoresis (PFGE) is a technique used for the separation of large DNA molecules by applying to a gel matrix an electric field that periodically changes direction. Pulsed-field gel electrophoresis is a method used to separate large segments of DNA using an alternating and cross field. In a uniform magnetic field, components larger than 50kb move through the gel in a zigzag pattern, allowing for more effective separation of DNA molecules. This method is commonly used in microbiology for typing bacteria and is a valuable tool for epidemiological studies and gene mapping in microbes and mammalian cells. It also played a role in the development of large-insert cloning systems such as bacterial and yeast artificial chromosomes.
PFGE can be used to determine the genetic similarity between bacteria, as close and similar species will have similar profiles while dissimilar ones will have different profiles. This feature is useful in identifying the prevalent agent of a disease. Additionally, it can be used to monitor and evaluate micro-organisms in clinical samples, soil and water. It is also considered a reliable and standard method in vaccine preparation. In recent years, PFGE has been widely used as a powerful tool for controlling, preventing and monitoring diseases in different populations
Discovery
The discovery of PFGE can be traced back to the late 1970s and early 1980s. One of the earliest references to the use of PFGE for DNA analysis is a 1977 paper by Dr. David Burke and colleagues at the University of Colorado, where they described a method of separating DNA molecules based on their size using conventional gel electrophoresis. The first reference to the use of the term "pulsed-field gel electrophoresis" appears in a 1983 paper by Dr. Richard L. Sweeley and colleagues at the DuPont Company, where they described a method of separating large DNA molecules (over 50 kb) by applying a series of alternating electric fields to a gel matrix. In the |
https://en.wikipedia.org/wiki/David%20May%20%28computer%20scientist%29 | Michael David May FRS FREng (born 24 February 1951) is a British computer scientist. He is a Professor in the Department of Computer Science at the University of Bristol and founder of XMOS Semiconductor, serving until February 2014 as the chief technology officer.
May was lead architect for the transputer. As of 2017, he holds 56 patents, all in microprocessors and multi-processing.
Life and career
May was born in Holmfirth, Yorkshire, England and attended Queen Elizabeth Grammar School, Wakefield. From 1969 to 1972 he was a student at King's College, Cambridge, University of Cambridge, at first studying Mathematics and then Computer Science in the University of Cambridge Mathematical Laboratory, now the University of Cambridge Computer Laboratory.
He moved to the University of Warwick and started research in robotics. The challenges of implementing sensing and control systems led him to design and implement an early concurrent programming language, EPL, which ran on a cluster of single-board microcomputers connected by serial communication links. This early work brought him into contact with Tony Hoare and Iann Barron: one of the founders of Inmos.
When Inmos was formed in 1978, May joined to work on microcomputer architecture, becoming lead architect of the transputer and designer of the associated programming language Occam. This extended his earlier work and was also influenced by Tony Hoare, who was at the time working on CSP and acting as a consultant to Inmos.
The prototype of the transputer was called the Simple 42 and was completed in 1982. The first production transputers, the T212 and T414, followed in 1985; the T800 floating point transputer in 1987. May initiated the design of one of the first VLSI packet switches, the C104, together with the communications system of the T9000 transputer.
Working closely with Tony Hoare and the Programming Research Group at Oxford University, May introduced formal verification techniques into the design of the |
https://en.wikipedia.org/wiki/Pythagorean%20prime | A Pythagorean prime is a prime number of the Pythagorean primes are exactly the odd prime numbers that are the sum of two squares; this characterization is Fermat's theorem on sums of two squares.
Equivalently, by the Pythagorean theorem, they are the odd prime numbers for which is the length of the hypotenuse of a right triangle with integer legs, and they are also the prime numbers for which itself is the hypotenuse of a primitive Pythagorean triangle. For instance, the number 5 is a Pythagorean prime; is the hypotenuse of a right triangle with legs 1 and 2, and 5 itself is the hypotenuse of a right triangle with legs 3 and 4.
Values and density
The first few Pythagorean primes are
By Dirichlet's theorem on arithmetic progressions, this sequence is infinite. More strongly, for each , the numbers of Pythagorean and non-Pythagorean primes up to are approximately equal. However, the number of Pythagorean primes up to is frequently somewhat smaller than the number of non-Pythagorean primes; this phenomenon is known as For example, the only values of up to 600000 for which there are more Pythagorean than non-Pythagorean odd primes less than or equal to n are 26861
Representation as a sum of two squares
The sum of one odd square and one even square is congruent to 1 mod 4, but there exist composite numbers such as 21 that are and yet cannot be represented as sums of two squares. Fermat's theorem on sums of two squares states that the prime numbers that can be represented as sums of two squares are exactly 2 and the odd primes congruent to The representation of each such number is unique, up to the ordering of the two squares.
By using the Pythagorean theorem, this representation can be interpreted geometrically: the Pythagorean primes are exactly the odd prime numbers such that there exists a right triangle, with integer legs, whose hypotenuse has They are also exactly the prime numbers such that there exists a right triangle with integer sides wh |
https://en.wikipedia.org/wiki/Dulmage%E2%80%93Mendelsohn%20decomposition | In graph theory, the Dulmage–Mendelsohn decomposition is a partition of the vertices of a bipartite graph into subsets, with the property that two adjacent vertices belong to the same subset if and only if they are paired with each other in a perfect matching of the graph. It is named after A. L. Dulmage and Nathan Mendelsohn, who published it in 1958. A generalization to any graph is the Edmonds–Gallai decomposition, using the Blossom algorithm.
Construction
The Dulmage-Mendelshon decomposition can be constructed as follows. (it is attributed to who in turn attribute it to ).
Let G be a bipartite graph, M a maximum-cardinality matching in G, and V0 the set of vertices of G unmatched by M (the "free vertices"). Then G can be partitioned into three parts:
E - the even vertices - the vertices reachable from V0 by an M-alternating path of even length.
O - the odd vertices - the vertices reachable from V0 by an M-alternating path of odd length.
U - the unreachable vertices - the vertices unreachable from V0 by an M-alternating path.
An illustration is shown on the left. The bold lines are the edges of M. The weak lines are other edges of G. The red dots are the vertices of V0. Note that V0 is contained in E, since it is reachable from V0 by a path of length 0.
Based on this decomposition, the edges in G can be partitioned into six parts according to their endpoints: E-U, E-E, O-O, O-U, E-O, U-U. This decomposition has the following properties:
The sets E, O, U are pairwise-disjoint. Proof: U is disjoint from E and O by definition. To prove that E and O are disjoint, suppose that some vertex v has both an even-length alternating path to an unmatched vertex u1, and an odd-length alternating path to an unmatched vertex u2. Then, concatenating these two paths yields an augmenting path from u1 through v to u2. But this contradicts the assumption that M is a maximum-cardinality matching.
The sets E, O, U do not depend on the maximum-cardinality matching M |
https://en.wikipedia.org/wiki/Primitive%20%28phylogenetics%29 | In phylogenetics, a primitive (or ancestral) character, trait, or feature of a lineage or taxon is one that is inherited from the common ancestor of a clade (or clade group) and has undergone little change since. Conversely, a trait that appears within the clade group (that is, is present in any subgroup within the clade but not all) is called advanced or derived. A clade is a group of organisms that consists of a common ancestor and all its lineal descendants.
A primitive trait is the original condition of that trait in the common ancestor; advanced indicates a notable change from the original condition. These terms in biology contain no judgement about the sophistication, superiority, value or adaptiveness of the named trait. "Primitive" in biology means only that the character appeared first in the common ancestor of a clade group and has been passed on largely intact to more recent members of the clade. "Advanced" means the character has evolved within a later subgroup of the clade.
Phylogenetics is utilized to determine evolutionary relationships and relatedness, to ultimately depict accurate evolutionary lineages. Evolutionary relatedness between living species can be connected by descent from common ancestry. These evolutionary lineages can thereby be portrayed through a phylogenetic tree, or cladogram, where varying relatedness amongst species is evidently depicted. Through this tree, organisms can be categorized by divergence from the common ancestor, and primitive characters, to clades of organisms with shared derived character states. Furthermore, cladograms allow researchers to view the changes and evolutionary alterations occurring in a species over time as they move from primitive characters to varying derived character states.
Cladograms are important for scientists as they allow them to classify and hypothesize the origin and future of organisms. Cladograms allow scientists to propose their evolutionary scenarios about the lineage from a prim |
https://en.wikipedia.org/wiki/Fraser%20syndrome | Fraser syndrome (also known as Meyer-Schwickerath's syndrome, Fraser-François syndrome, or Ullrich-Feichtiger syndrome) is an autosomal recessive congenital disorder, identified by several developmental anomalies. Fraser syndrome is named for the geneticist George R. Fraser, who first described the syndrome in 1962.
Signs and symptoms
It is characterized by developmental defects including cryptophthalmos (where the eyelids fail to separate in each eye), and intersex development in the genitals (such as micropenis, or clitoromegaly) and cryptorchidism Congenital malformations of the nose, ears, larynx and renal system, as well as developmental delays, manifest occasionally. Syndactyly (fused fingers or toes) has also been noted.
Genetics
The genetic background of this disease has been linked to a gene called FRAS1, which seems to be involved in skin epithelial morphogenesis during early development. It has also been associated with FREM2 and with GRIP1.
Mapping
By autozygosity mapping, McGregor et al. (2003) located the Fraser syndrome locus to chromosome 4q21.
Genetic Heterogeneity
In 6 of 18 consanguineous families with Fraser syndrome, van Haelst et al. (2008) excluded linkage to both the FRAS1 and FREM2 genes, indicating genetic heterogeneity.
Molecular genetics
In 5 families with Fraser syndrome, McGregor et al. (2003) identified 5 homozygous mutations in the FRAS1 gene (e.g., 607830.0001), which encodes a putative extracellular matrix (ECM) protein.
In 2 families with Fraser syndrome unlinked to the FRAS1 gene, Jadeja et al. (2005) found a homozygous missense mutation in the FREM2 gene (608945.0001).
In an infant girl with Fraser syndrome, Slavotinek et al. (2006) identified compound heterozygosity for a deletion (607830.0006) and an insertion (607830.0007) in the FRAS1 gene, inherited from her mother and her father, respectively.
Cavalcanti et al. (2007) described 2 stillborn Brazilian male siblings, born at 25 and 29 weeks' gestation, respectively. |
https://en.wikipedia.org/wiki/Logopenic%20progressive%20aphasia | Logopenic progressive aphasia (LPA) is a variant of primary progressive aphasia. It is defined clinically by impairments in naming and sentence repetition. It is similar to conduction aphasia and is associated with atrophy to the left posterior temporal cortex and inferior parietal lobule. It is suspected that an atypical form of Alzheimer's disease is the most common cause of logopenic progressive aphasia.
Although patients with the logopenic variant of PPA are still able to produce speech, their speech rate may be significantly slowed due to word retrieval difficulty. Over time, they may experience the inability to retain lengthy information, causing problems with understanding complex verbal information. Some additional behavioral features include irritability, anxiety and agitation.
Compared to other subtypes of primary progressive aphasia, the logopenic variant has been found to be associated with cognitive and behavioral characteristics. Studies have shown that patients with the logopenic variant perform significantly worse on tests of calculation than other primary progressive aphasia patients. Several logopenic variant patients, especially those with Alzheimer's disease pathology, have also been found to perform poorly on memory tasks.
Logopenic progressive aphasia is caused by damage to segregated brain regions, specifically the inferior parietal lobe and superior temporal regions. Difficulties in naming are produced from the thinning of the inferior parietal lobe. Damage to the dorsal pathways creates language deficiency in patients that is characteristic of logopenic progressive aphasia.
See also
Aphasia
Dementia
Early-onset Alzheimer's disease |
https://en.wikipedia.org/wiki/Domainz | Domainz Limited was the original .nz registry operator and is now an ICANN accredited domain name registrar and web host.
IANA delegated the .nz namespace to John Houlker on 19 January 1987, and the University of Waikato issued .nz domain names and maintained the .nz registry during the early part of Internet availability in New Zealand.
During 1996, as Internet use was flourishing in New Zealand, and operation of the .nz registry was becoming burdensome on the University of Waikato, John Houlker, IANA and The Internet Society of New Zealand (Isocnz) agreed to a redelegation of the .nz name to Isocnz.
The University of Waikato was contracted to continue hosting the .nz namespace until Isocnz was in a position to assume full responsibility for the Domain Name System (DNS).
Isocnz established a subsidiary company, “The New Zealand Internet Registry Ltd”, trading as Domainz, to run the .nz registry, on 15 April 1997.
Domainz commenced allocating domain names, to both companies and individuals, evolving what was known as the Domainz Registration System (DRS).
Concern over a new online registry system, which was suffering a welter of problems, and opposition to a lawsuit (against Alan Brown, the founder of ORBS) both being championed by Domainz CEO Patrick O'Brien saw all available Isocnz council seats (and subsequently the Domainz board) filled by "rebel" members in elections in July 2000.
The SRS was implemented and became live on 14 October 2002, with Domainz as the sole registrar, acting in a stabilising role, until the first competitive registrar connected to the shared registry on 7 December 2002.
Domainz remained as the stabilising registrar until September 2003.
In September 2003, Domainz was acquired by Australian-based registrar Melbourne IT Limited.
In October 2003 there were in excess of 40 registrars interacting with the .nz Shared Registry System. |
https://en.wikipedia.org/wiki/Gordon%20Plotkin | Gordon David Plotkin, (born 9 September 1946) is a theoretical computer scientist in the School of Informatics at the University of Edinburgh. Plotkin is probably best known for his introduction of structural operational semantics (SOS) and his work on denotational semantics. In particular, his notes on A Structural Approach to Operational Semantics were very influential. He has contributed to many other areas of computer science.
Education
Plotkin was educated at the University of Glasgow and the University of Edinburgh, gaining his Bachelor of Science degree in 1967 and PhD in 1972 supervised by Rod Burstall.
Career and research
Plotkin has remained at Edinburgh, and was, with Burstall and Robin Milner, a co-founder of the Laboratory for Foundations of Computer Science (LFCS). His former doctoral students include Luca Cardelli, Philippa Gardner, Doug Gurr, Eugenio Moggi, and Lǐ Wèi.
Awards and honours
Plotkin was elected a Fellow of the Royal Society (FRS) in 1992, and a Fellow of the Royal Society of Edinburgh (FRSE) and is a Member of the Academia Europæa and the American Academy of Arts and Sciences. He is also a winner of the Royal Society Wolfson Research Merit Award. Plotkin received the Milner Award in 2012 for "his fundamental research into programming semantics with lasting impact on both the principles and design of programming languages." His nomination for the Royal Society reads: |
https://en.wikipedia.org/wiki/Microsoft%20Windows%20SDK | Microsoft Windows SDK, and its predecessors Platform SDK, and .NET Framework SDK, are software development kits (SDKs) from Microsoft that contain documentation, header files, libraries, samples and tools required to develop applications for Microsoft Windows and .NET Framework. Platform SDK specializes in developing applications for Windows 2000, XP and Windows Server 2003. .NET Framework SDK is dedicated to developing applications for .NET Framework 1.1 and .NET Framework 2.0. Windows SDK is the successor of the two and supports developing applications for Windows XP and later, as well as .NET Framework 3.0 and later.
Features
Platform SDK is the successor of the original Microsoft Windows SDK for Windows 3.1x and Microsoft Win32 SDK for Windows 9x. It was released in 1999 and is the oldest SDK. Platform SDK contains compilers, tools, documentations, header files, libraries and samples needed for software development on IA-32, x64 and IA-64 CPU architectures. however, came to being with .NET Framework. Starting with Windows Vista, the Platform SDK, .NET Framework SDK, Tablet PC SDK and Windows Media SDK are replaced by a new unified kit called Windows SDK. However, the .NET Framework 1.1 SDK is not included since the .NET Framework 1.1 does not ship with Windows Vista. (Windows Media Center SDK for Windows Vista ships separately.) DirectX SDK was merged into Windows SDK with the release of Windows 8.
Windows SDK allows the user to specify the components to be installed and where to install them. It integrates with Visual Studio, so that multiple copies of the components that both have are not installed; however, there are compatibility caveats if either of the two is not from the same era. Information shown can be filtered by content, such as showing only new Windows Vista content, only .NET Framework content, or showing content for a specific language or technology.
Windows SDKs are available for free; they were once available on Microsoft Download Center bu |
https://en.wikipedia.org/wiki/Enon%20%28robot%29 | Enon is a personal assistant robot first offered for sale in September 2005. Enon was developed by two companies: Fujitsu Frontech Limited and Fujitsu Laboratories Ltd. The six-million yen (US$60,000) rolling robot is self-guiding, with limited speech recognition and synthesis. Enon can amongst others be used to provide guidance, transport objects, escort guests and perform security patrolling, according to the organization. Enon, an English acronym for "Exciting Nova On Network," can pick up and carry roughly in its arms and comes without software.
External links
Fujitsu |
https://en.wikipedia.org/wiki/BGP%20hijacking | BGP hijacking (sometimes referred to as prefix hijacking, route hijacking or IP hijacking) is the illegitimate takeover of groups of IP addresses by corrupting Internet routing tables maintained using the Border Gateway Protocol (BGP).
Background
The Internet is a global network in enabling any connected host, identified by its unique IP address, to talk to any other, anywhere in the world. This is achieved by passing data from one router to another, repeatedly moving each packet closer to its destination, until it is hopefully delivered. To do this, each router must be regularly supplied with up-to-date routing tables. At the global level, individual IP addresses are grouped together into prefixes. These prefixes will be originated, or owned, by an autonomous system (AS) and the routing tables between ASes are maintained using the Border Gateway Protocol (BGP).
A group of networks that operates under a single external routing policy is known as an autonomous system. For example, Sprint, Verizon, and AT&T each are an AS. Each AS has its own unique AS identifier number. BGP is the standard routing protocol used to exchange information about IP routing between autonomous systems.
Each AS uses BGP to advertise prefixes that it can deliver traffic to. For example, if the network prefix is inside AS 64496, then that AS will advertise to its provider(s) and/or peer(s) that it can deliver any traffic destined for .
Although security extensions are available for BGP, and third-party route DB resources exist for validating routes, by default the BGP protocol is designed to trust all route announcements sent by peers, and few ISPs rigorously enforce checks on BGP sessions.
Mechanism
IP hijacking can occur deliberately or by accident in one of several ways:
An AS announces that it originates a prefix that it does not actually originate.
An AS announces a more specific prefix than what may be announced by the true originating AS.
An AS announces that it can ro |
https://en.wikipedia.org/wiki/Homeobox%20protein%20NANOG | Homeobox protein NANOG (hNanog) is a transcriptional factor that helps embryonic stem cells (ESCs) maintain pluripotency by suppressing cell determination factors. hNanog is encoded in humans by the NANOG gene. Several types of cancer are associated with NANOG.
Etymology
The name NANOG derives from Tír na nÓg (Irish for "Land of the Young"), a name given to the Celtic Otherworld in Irish and Scottish mythology.
Structure
The human hNanog protein coded by the NANOG gene, consists of 305 amino acids and possesses 3 functional domains: the N-terminal domain, the C- terminal domain, and the conserved homeodomain motif. The homeodomain region facilitates DNA binding. The NANOG is located on chromosome 12, and the mRNA contains a 915 bp open reading frame (ORF) with 4 exons and 3 introns.
The N-terminal region of hNanog is rich in serine, threonine and proline residues, and the C-terminus contains a tryptophan-rich domain. The homeodomain in hNANOG ranges from residues 95 to 155. There are also additional NANOG genes (NANOG2, NANOG p8) which potentially affect ESCs' differentiation. Scientists have shown that NANOG is fundamental for self-renewal and pluripotency, and NANOG p8 is highly expressed in cancer cells.
Function
NANOG is a transcription factor in embryonic stem cells (ESCs) and is thought to be a key factor in maintaining pluripotency. NANOG is thought to function in concert with other factors such as POU5F1 (Oct-4) and SOX2 to establish ESC identity. These cells offer an important area of study because of their ability to maintain pluripotency. In other words, these cells have the ability to become virtually any cell of any of the three germ layers (endoderm, ectoderm, mesoderm). It is for this reason that understanding the mechanisms that maintain a cell's pluripotency is critical for researchers to understand how stem cells work, and may lead to future advances in treating degenerative diseases.
NANOG has been described to be expressed in the poster |
https://en.wikipedia.org/wiki/IEEE%20Transactions%20on%20Software%20Engineering | The IEEE Transactions on Software Engineering is a monthly peer-reviewed scientific journal published by the IEEE Computer Society. It was established in 1975 and covers the area of software engineering. It is considered the leading journal in this field.
Abstracting and indexing
The journal is abstracted and indexed in the Science Citation Index Expanded and Current Contents/Engineering, Computing & Technology. According to the Journal Citation Reports, the journal has a 2021 impact factor of 9.322.
Past editors-in-chief
See also
IEEE Software
IET Software |
https://en.wikipedia.org/wiki/Floer%20homology | In mathematics, Floer homology is a tool for studying symplectic geometry and low-dimensional topology. Floer homology is a novel invariant that arises as an infinite-dimensional analogue of finite-dimensional Morse homology. Andreas Floer introduced the first version of Floer homology, now called Lagrangian Floer homology, in his proof of the Arnold conjecture in symplectic geometry. Floer also developed a closely related theory for Lagrangian submanifolds of a symplectic manifold. A third construction, also due to Floer, associates homology groups to closed three-dimensional manifolds using the Yang–Mills functional. These constructions and their descendants play a fundamental role in current investigations into the topology of symplectic and contact manifolds as well as (smooth) three- and four-dimensional manifolds.
Floer homology is typically defined by associating to the object of interest an infinite-dimensional manifold and a real valued function on it. In the symplectic version, this is the free loop space of a symplectic manifold with the symplectic action functional. For the (instanton) version for three-manifolds, it is the space of SU(2)-connections on a three-dimensional manifold with the Chern–Simons functional. Loosely speaking, Floer homology is the Morse homology of the function on the infinite-dimensional manifold. A Floer chain complex is formed from the abelian group spanned by the critical points of the function (or possibly certain collections of critical points). The differential of the chain complex is defined by counting the function's gradient flow lines connecting certain pairs of critical points (or collections thereof). Floer homology is the homology of this chain complex.
The gradient flow line equation, in a situation where Floer's ideas can be successfully applied, is typically a geometrically meaningful and analytically tractable equation. For symplectic Floer homology, the gradient flow equation for a path in the loop |
https://en.wikipedia.org/wiki/Set%20Theory%3A%20An%20Introduction%20to%20Independence%20Proofs | Set Theory: An Introduction to Independence Proofs is a textbook and reference work in set theory by Kenneth Kunen. It starts from basic notions, including the ZFC axioms, and quickly develops combinatorial notions such as trees, Suslin's problem, ◊, and Martin's axiom. It develops some basic model theory (rather specifically aimed at models of set theory) and the theory of Gödel's constructible universe L. The book then proceeds to describe the method of forcing.
Kunen completely rewrote the book for the 2011 edition (under the title "Set Theory"), including more model theory. |
https://en.wikipedia.org/wiki/Low-dropout%20regulator | A low-dropout regulator (LDO regulator) is a DC linear voltage regulator that can operate even when the supply voltage is very close to the output voltage.
The advantages of an LDO regulator over other DC-to-DC voltage regulators include: the absence of switching noise (in contrast to switching regulators); smaller device size (as neither large inductors nor transformers are needed); and greater design simplicity (usually consists of a reference, an amplifier, and a pass element). The disadvantage is that linear DC regulators must dissipate heat in order to operate.
History
The adjustable low-dropout regulator debuted on April 12, 1977 in an Electronic Design article entitled "Break Loose from Fixed IC Regulators". The article was written by Robert Dobkin, an IC designer then working for National Semiconductor. Because of this, National Semiconductor claims the title of "LDO inventor". Dobkin later left National Semiconductor in 1981 and founded Linear Technology where he was the chief technology officer.
Components
The main components are a power FET and a differential amplifier (error amplifier). One input of the differential amplifier monitors the fraction of the output determined by the resistor ratio of R1 and R2. The second input to the differential amplifier is from a stable voltage reference (bandgap reference). If the output voltage rises too high relative to the reference voltage, the drive to the power FET changes to maintain a constant output voltage.
Regulation
Low-dropout (LDO) regulators operate similarly to all linear voltage regulators. The main difference between LDO and non-LDO regulators is their schematic topology. Instead of an emitter follower topology, low-dropout regulators consist of an open collector or open drain topology, where the transistor may be easily driven into saturation with the voltages available to the regulator. This allows the voltage drop from the unregulated voltage to the regulated voltage to be as low as (limited t |
https://en.wikipedia.org/wiki/Ultraviolet%20fixed%20point | In a quantum field theory, one may calculate an effective or running coupling constant that defines the coupling of the theory measured at a given momentum scale. One example of such a coupling constant is the electric charge.
In approximate calculations in several quantum field theories, notably quantum electrodynamics and theories of the Higgs particle, the running coupling appears to become infinite at a finite momentum scale. This is sometimes called the Landau pole problem.
It is not known whether the appearance of these inconsistencies is an artifact of the approximation, or a real fundamental problem in the theory. However, the problem can be avoided if an ultraviolet or UV fixed point appears in the theory. A quantum field theory has a UV fixed point if its renormalization group flow approaches a fixed point in the ultraviolet (i.e. short length scale/large energy) limit. This is related to zeroes of the beta-function appearing in the Callan–Symanzik equation. The large length scale/small energy limit counterpart is the infrared fixed point.
Specific cases and details
Among other things, it means that a theory possessing a UV fixed point may not be an effective field theory, because it is well-defined at arbitrarily small distance scales. At the UV fixed point itself, the theory can behave as a conformal field theory.
The converse statement, that any QFT which is valid at all distance scales (i.e. isn't an effective field theory) has a UV fixed point is false. See, for example, cascading gauge theory.
Noncommutative quantum field theories have a UV cutoff even though they are not effective field theories.
Physicists distinguish between trivial and nontrivial fixed points. If a UV fixed point is trivial (generally known as Gaussian fixed point), the theory is said to be asymptotically free. On the other hand, a scenario, where a non-Gaussian (i.e. nontrivial) fixed point is approached in the UV limit, is referred to as asymptotic safety. Asymptotically |
https://en.wikipedia.org/wiki/Memoirs%20of%20an%20Invisible%20Man%20%28film%29 | Memoirs of an Invisible Man is a 1992 American comedy-drama film directed by John Carpenter and starring Chevy Chase, Daryl Hannah, Sam Neill, Michael McKean and Stephen Tobolowsky. The film is loosely based on Memoirs of an Invisible Man, a 1987 novel by H.F. Saint. According to screenwriter William Goldman's book Which Lie Did I Tell?, the film was initially developed for director Ivan Reitman; however, this version never came to fruition, due to disagreements between Reitman and Chase. The film was a critical and commercial failure.
Plot
Nick Halloway is a stock analyst who spends most of his life avoiding responsibility and connections with other people. At his favorite bar, the Academy Club, his friend George Talbot introduces him to Alice Monroe, a TV documentary producer. Sharing an instant attraction, Nick and Alice make out in the ladies' room and set a lunch date for Friday.
The following morning, a hungover Nick attends a shareholders' meeting at Magnascopic Laboratories. Unable to endure the droning presentation by Dr. Bernard Wachs, Nick leaves the room for a nap. A lab technician accidentally spills his mug of coffee onto a computer console, causing a meltdown, and the entire building is evacuated. The building seems to explode, but there is no debris. Instead, much of the building is rendered invisible, including Nick.
Shady CIA operative David Jenkins arrives on the scene and discovers Nick's condition. While they are transferring him to an ambulance, the agents joke about how Nick will spend the rest of his life being studied by scientists. In a panic, Nick flees. Jenkins convinces his supervisor Warren Singleton not to notify CIA headquarters so that they can capture and take credit for Nick, who could become the perfect secret agent.
Nick hides at the Academy Club. He locates Dr. Wachs and asks for his help to reverse his condition. Wachs agrees to help, but Jenkins kills him to keep Nick's invisibility a secret. Jenkins' team gets a hold of N |
https://en.wikipedia.org/wiki/Pod%20slurping | Pod slurping is the act of using a portable data storage device such as an iPod digital audio player to illicitly download large quantities of confidential data by directly plugging it into a computer where the data are held, and which may be on the inside of a firewall.
There has been some work in the development of fixes to the problem, including a number of third-party security products that allow companies to set security policies related to USB device use, and features within operating systems that allow IT administrators or users to disable the USB port altogether. Unix-based or Unix-like systems can easily prevent users from mounting storage devices, and Microsoft has released instructions for preventing users from installing USB mass storage devices on its operating systems.
Additional measures include physical obstruction of the USB ports, with measures ranging from the simple filling of ports with epoxy resin to commercial solutions which deposit a lockable plug into the port.
See also
Data theft
Bluesnarfing
Sneakernet |
https://en.wikipedia.org/wiki/Tinkerbell%20map | The Tinkerbell map is a discrete-time dynamical system given by:
Some commonly used values of a, b, c, and d are
Like all chaotic maps, the Tinkerbell Map has also been shown to have periods; after a certain number of mapping iterations any given point shown in the map to the right will find itself once again at its starting location.
The origin of the name is uncertain; however, the graphical picture of the system (as shown to the right) shows a similarity to the movement of Tinker Bell over Cinderella Castle, as shown at the beginning of all films produced by Disney.
See also
List of chaotic maps |
https://en.wikipedia.org/wiki/Quatrefoil | A quatrefoil (anciently caterfoil) is a decorative element consisting of a symmetrical shape which forms the overall outline of four partially overlapping circles of the same diameter. It is found in art, architecture, heraldry and traditional Christian symbolism. The word 'quatrefoil' means "four leaves", from the Latin , "four", plus , "leaf"; the term refers specifically to a four-leafed clover, but applies in general to four-lobed shapes in various contexts. In recent years, several luxury brands have attempted to fraudulently assert creative rights related to the symbol, which naturally predates any of those brands' creative development. A similar shape with three rings is called a trefoil.
History
The quatrefoil enjoyed its peak popularity during the Gothic and Renaissance eras. It is most commonly found as tracery, mainly in Gothic architecture, where a quatrefoil often may be seen at the top of a Gothic arch, sometimes filled with stained glass. Although the design is often referred to as of Islamic origin, there are examples of its use that precede the birth of Islam by almost 200 years. The Monastery of Stoudios in Constantinople, built in 462 AD, features arches seen to be the product of taking a regular quatrefoil and dividing it in half.
In ancient Mesoamerica
In ancient Mesoamerica, the quatrefoil is frequently portrayed on Olmec and Mayan monuments, such as at La Blanca, Guatemala where it dates to approximately 850 BC. The quatrefoil depicts the opening of the cosmic central axis at the crossroads of the four cardinal directions, representing the passageway between the celestial and the underworld.
Another early example of a quatrefoil is found at Chalcatzingo, Morelos state, Mexico, the city that flourished between 700 BCE and 500 BCE. Both a full quatrefoil, and a partial portrayal of quatrefoil are found on monuments here. In the latter case, one half of a quatrefoil represents the opening of a cave where an important personage is seated. This |
https://en.wikipedia.org/wiki/UTEC | UTEC (University of Toronto Electronic Computer Mark I) was a computer built at the University of Toronto (UofT) in the early 1950s. It was the first computer in Canada, one of the first working computers in the world, although only built in a prototype form while awaiting funding for expansion into a full-scale version. This funding was eventually used to purchase a surplus Manchester Mark 1 from Ferranti in the UK instead, and UTEC quickly disappeared.
Background
Immediately after the end of World War II several members of the UofT staff met informally as the Committee on Computing Machines to discuss their computation needs over the next few years. In 1946 a small $1,000 grant was used to send one of the group's members to tour several US research labs to see their progress on computers and try to see what was possible given UofT's likely funding. Due to UofT's preeminent position in the Canadian research world, the tour was also followed by members of the Canadian Research Council.
In January 1947 the committee delivered a report suggesting the creation of a formal Computing Center, primarily as a service bureau to provide computing services both to the university and commercial interests, as well as the nucleus of a research group into computing machinery. Specifically they recommended the immediate renting of an IBM mechanical punched card-based calculator, building a simple differential analyzer, and the eventual purchase or construction of an electronic computer. The report noted that funding should be expected from both the National Research Council (NRC) and the Defense Research Board (DRB).
The DRB soon provided a grant of $6,500 to set up the Computation Center, with the Committee eventually selecting Kelly Gotlieb to run it. Additional funding followed in February 1948 with a $20,000 a year grant from a combined pool set up by the DRB and NRC. Although this was less than was hoped for, the IBM machinery was soon in place and being used to calculate s |
https://en.wikipedia.org/wiki/Ecotoxicology | Ecotoxicology is the study of the effects of toxic chemicals on biological organisms, especially at the population, community, ecosystem, and biosphere levels. Ecotoxicology is a multidisciplinary field, which integrates toxicology and ecology.
The ultimate goal of ecotoxicology is to reveal and predict the effects of pollution within the context of all other environmental factors. Based on this knowledge the most efficient and effective action to prevent or remediate any detrimental effect can be identified. In those ecosystems that are already affected by pollution, ecotoxicological studies can inform the choice of action to restore ecosystem services, structures, and functions efficiently and effectively.
Ecotoxicology differs from environmental toxicology in that it integrates the effects of stressors across all levels of biological organisation from the molecular to whole communities and ecosystems, whereas environmental toxicology includes toxicity to humans and often focuses upon effects at the organism level and below.
History
Ecotoxicology is a relatively young discipline that made its debuts in the 1970s in the realm of the environmental sciences. Its methodological aspects, derived from toxicology, are widened to encompass the human environmental field and the biosphere at large. While conventional toxicology limits its investigations to the cellular, molecular and organismal scales, ecotoxicology strives to assess the impact of chemical, physicochemical and biological stressors, on populations and communities exhibiting the impacts on entire ecosystems. In this respect, ecotoxicology again takes into consideration dynamic balance under strain.
Ecotoxicology emerged after pollution events that occurred after World War II heightened awareness on the impact of toxic chemical and wastewater discharges towards humankind and the environment. The term "Ecotoxicology" was uttered for the first time in 1969 by René Truhaut, a toxicologist, during an environm |
https://en.wikipedia.org/wiki/Numeronym | A numeronym is a number-based word.
Anne H. Soukhanov, editor of the Microsoft Encarta College Dictionary, gives the original meaning of the term as "a telephone number that spells a word or a name" on a telephone dial/numpad.
A number may also denote how many times the character before or after it is repeated. This is typically used to represent a name or phrase in which several consecutive words start with the same letter, as in W3 (World Wide Web) or W3C (World Wide Web Consortium).
Types
Homophone
Most commonly, a numeronym is a word where a number is used to form an abbreviation (albeit not an acronym or an initialism). Pronouncing the letters and numbers may sound similar to the full word, as in "K9" (pronounced "kay-nine") for "canine, relating to dogs".
Examples
sk8r: Skater
B4: Before
l8r: Later; L8R, also sometimes abbreviated as L8ER, is commonly used in chat rooms and other text based communications as a way of saying goodbye.
G2G: "Good to go", "got to go", or "get together"
P2P: "pay to play" or "peer-to-peer"
F2P: "free to play"
T2UL/T2YL: "talk to you later"
B2B: "business to business"
B2C: "business to consumer"
Numerical contractions
Alternatively, letters between the first and last letters of a word may be replaced by a number representing the number of letters omitted, such as in "i18n" for "internationalization", where "18" stands in for the word's middle eighteen letters ("nternationalizatio"). Sometimes the last letter is also counted and omitted. These word shortenings are sometimes called alphanumeric acronyms, alphanumeric abbreviations, or numerical contractions. According to Tex Texin, the first numeronym of this kind was "S12n", the electronic mail account name given to Digital Equipment Corporation (DEC) employee Jan Scherpenhuizen by a system administrator because his surname was too long to be an account name. By 1985, colleagues who found Jan's name unpronounceable often referred to him verbally as "S12n" (ess-twe |
https://en.wikipedia.org/wiki/Linked%20numbering%20scheme | A linked numbering scheme (LNS) is a dialing procedure in effect in a service area within which call routing between adjacent exchanges does not require a dialing code. The term is only used in the United Kingdom, but not in the North American Numbering Plan.
United Kingdom
The largest linked numbering scheme in the UK is that for the London telephone area, formerly known as the London Director area. Within the area, several million subscribers can call each other by dialing a uniform code. For example, anyone calling from an (020) number can reach Transport for London travel enquiries by dialing 7222 1234.
Smaller schemes apply outside London. Uxbridge, for example, has the subscriber trunk dialing (STD) code 01895. Uxbridge exchange is the parent for Denham, Harefield, Ruislip and West Drayton; anyone connected to any of those exchanges can call any of the others without having to prefix the number with 01895. This is achieved by giving subscriber lines on each exchange different prefix numbers, thus: all numbers are six-figure; Denham numbers start with 83, Harefield with 82, Ruislip with 6 and West Drayton with 4. Uxbridge numbers start with 2 or 81. All calls must have all six digits dialled - even if a subscriber is on Denham exchange and is calling another subscriber on Denham exchange, they must still dial 83xxxx.
Incoming calls from any other exchange for a subscriber on any of the five exchanges must all be prefixed with the same 01895 code.
North America
The terminology linked numbering scheme is not used in the North American Numbering Plan (NANP).
A local call in this scheme, standardized in 1948 for the introduction of direct-dial long-distance calling, was originally dialled as a fixed-length seven-digit number and did not require an area code. In some cases, a local call to a number just across an area code boundary could be seven digits if an exchange code protection scheme prevented the same prefixes being assigned to local numbers in the |
https://en.wikipedia.org/wiki/Logics%20for%20computability | Logics for computability are formulations of logic which
capture some aspect of computability as a basic notion. This usually involves a mix
of special logical connectives as well as semantics which explains how the logic is to be interpreted in a computational way.
Probably the first formal treatment of logic for computability is the realizability interpretation by Stephen Kleene in 1945, who gave an interpretation of intuitionistic number theory in terms of Turing machine computations. His motivation was to make precise the Heyting-Brouwer-Kolmogorov (BHK) interpretation of intuitionism, according to which proofs of mathematical statements are to be viewed as constructive procedures.
With the rise of many other kinds of logic, such as modal logic and linear logic, and novel semantic models, such as game semantics, logics for computability have been formulated in several contexts. Here we mention two.
Modal logic for computability
Kleene's original realizability interpretation has received much attention among those who study connections between computability and logic. It was extended to full higher-order intuitionistic logic by Martin Hyland in 1982 who constructed the effective topos. In 2002, Steve Awodey, Lars Birkedal, and Dana Scott formulated a modal logic for computability which extended the usual realizability interpretation with two modal operators expressing the notion of being "computably true".
Japaridze's computability logic
"Computability Logic" is a proper noun referring to a research programme initiated by Giorgi Japaridze in 2003. Its ambition is to redevelop logic from a game-theoretic semantics. Such a semantics sees games as formal equivalents of interactive computational problems, and their "truth" as existence of algorithmic winning strategies. See Computability logic
See also
Computability logic
Game semantics
Interactive computation |
https://en.wikipedia.org/wiki/J%C3%B8rg%20Tofte%20Jebsen | Jørg Tofte Jebsen (27 April 1888 – 7 January 1922) was a physicist from Norway, where he was the first to work on Einstein's general theory of relativity. In this connection he became known after his early death for what many now call the Jebsen-Birkhoff theorem for the metric tensor outside a general, spherical mass distribution.
Biography
Jebsen was born and grew up in Berger, Vestfold, where his father Jens Johannes Jebsen ran two large textile mills. His mother was Agnes Marie Tofte and they had married in 1884. After elementary school he went through middle school and gymnasium in Oslo. He showed already then particular talents for mathematical topics.
After the final examen artium in 1906, he did not continue his academic studies at a university as would be normal at that time. He was meant to enter his father's company and spent for that purpose two years in Aachen in Germany where he studied textile manufacturing. After a shorter stay in England, he came back to Norway and started to work with his father.
But his interests for natural science took over so that in 1909 he started this field of study at University of Oslo. His work there was interrupted in the period 1911-12 when he was an assistant for Sem Sæland at the newly established Norwegian Institute of Technology (NTH) in Trondheim. Back in Oslo he took up investigations of X-ray crystallography with Lars Vegard. With his help he could pursue this work at University of Berlin starting in the spring of 1914. That was at the same time as Einstein took up his new position there.
Theory of relativity
During the stay in Berlin it became clear that his main interests were in theoretical physics and electrodynamics in particular. This is central to Einstein's special theory of relativity and would define his future work back in Norway. From 1916 he took a new job as assistant in Trondheim, but had to resign after a year because of health problems. In the summer of 1917 he married Magnhild Andresen in O |
https://en.wikipedia.org/wiki/Light%20Up%20%28puzzle%29 | Light Up (Japanese: 美術館 bijutsukan, art gallery), also called Akari (明かり, light) is a binary-determination logic puzzle published by Nikoli. As of 2011, three books consisting entirely of Light Up puzzles have been published by Nikoli.
Rules
Light Up is played on a rectangular grid of white and black cells. The player places light bulbs in white cells such that no two bulbs shine on each other, until the entire grid is lit up. A bulb sends rays of light horizontally and vertically, illuminating its entire row and column unless its light is blocked by a black cell. A black cell may have a number on it from 0 to 4, indicating how many bulbs must be placed adjacent to its four sides; for example, a cell with a 4 must have four bulbs around it, one on each side, and a cell with a 0 cannot have a bulb next to any of its sides. An unnumbered black cell may have any number of light bulbs adjacent to it, or none. Bulbs placed diagonally adjacent to a numbered cell do not contribute to the bulb count.
Solution methods
A typical starting point in the solution of a Light Up puzzle is to find a black cell with a 4, or a cell with a smaller number that is blocked on one or more sides (for example, a 3 against a wall or a 2 in a corner) and therefore has only one configuration of surrounding bulbs. After this step, other numbered cells may be illuminated on one or more sides, narrowing down the possible bulb configurations around them, and in some cases making only one configuration possible.
Another common technique is to look for a cell that is not yet lit, and determine if there is only one possible cell in which a bulb can be placed to light it up.
When it is unclear where to place a bulb, one may also place dots in white cells that cannot have bulbs, such as around a 0 or in places where a bulb would create a contradiction. For example, a light bulb placed diagonally adjacent to a 3 will block two of its surrounding cells, making it impossible to have three bulb |
https://en.wikipedia.org/wiki/State-universal%20coupled%20cluster | State-universal coupled cluster (SUCC) method is one of several multi-reference coupled-cluster (MR) generalizations of single-reference coupled cluster method. It was first formulated by Bogumił Jeziorski and Hendrik Monkhorst in their work published in Physical Review A in 1981. State-universal coupled cluster is often abbreviated as SUMR-CC or MR-SUCC. |
https://en.wikipedia.org/wiki/African%20Journal%20of%20AIDS%20Research | The African Journal of AIDS Research is a peer-reviewed medical journal published in 2002 by the National Inquiry Services Centre (Grahamstown, South Africa) on topics related related to understanding the social dimensions to AIDS in Africa. Launched to address the lack of an African-managed journal focussed on social-science research on HIV/AIDS in Africa, it is now co-published and distributed by Taylor and Francis. |
https://en.wikipedia.org/wiki/Electrophoresis%20%28disambiguation%29 | Electrophoresis is the motion of dispersed particles relative to a fluid under the influence of a spatially uniform electric field.
"Electrophoresis" can also refer to:
Interface and colloid science
Dielectrophoresis, similar motion in a space non-uniform electric field
Microelectrophoresis, a method of studying electrophoresis of various dispersed particles using optical microscopy
Electrophoretic light scattering, a method for measuring electrophoretic mobility based on dynamic light scattering
Molecular biology and biochemistry
Affinity electrophoresis, used to separate and characterize biomolecules on basis of their molecular characteristics through binding to another biomolecule
Capillary electrophoresis, commonly used to separate biomolecules by their charge and frictional forces
Gel electrophoresis, a technique used by scientists to separate molecules based on physical characteristics such as size, shape, or isoelectric point
electrophoresis of nucleic acids, a specific type of gel electrophoresis used to analyse DNA and RNA
electrophoresis of proteins, a specific type of gel electrophoresis used to analyse proteins
two-dimensional electrophoresis, a specific type of gel electrophoresis commonly used to analyse proteins which involves two separation mechanisms to separate molecules
SDS-PAGE, sodium dodecyl sulfate polyacrylamide gel electrophoresis, commonly used to analyse proteins
Immunoelectrophoresis, used to separate and characterize biomolecules on basis their molecular characteristics as well as binding of antibodies
Medicine
Iontophoresis, a way of rapidly administering drugs through the skin
Media support
Electrophoretic display, a device that displays media contents using charged pigment particles in an applied electric field
Other
Electrophoresis (journal)
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Colloidal chemistry
Electrophoresis
Laboratory techniques |
https://en.wikipedia.org/wiki/Extremal%20combinatorics | Extremal combinatorics is a field of combinatorics, which is itself a part of mathematics. Extremal combinatorics studies how large or how small a collection of finite objects (numbers, graphs, vectors, sets, etc.) can be, if it has to satisfy certain restrictions.
Much of extremal combinatorics concerns classes of sets; this is called extremal set theory. For instance, in an n-element set, what is the largest number of k-element subsets that can pairwise intersect one another? What is the largest number of subsets of which none contains any other? The latter question is answered by Sperner's theorem, which gave rise to much of extremal set theory.
Another kind of example: How many people can be invited to a party where among each three people there are two who know each other and two who don't know each other? Ramsey theory shows that at most five persons can attend such a party. Or, suppose we are given a finite set of nonzero integers, and are asked to mark as large a subset as possible of this set under the restriction that the sum of any two marked integers cannot be marked. It appears that (independent of what the given integers actually are) we can always mark at least one-third of them.
See also
Extremal graph theory
Sauer–Shelah lemma
Erdős–Ko–Rado theorem
Kruskal–Katona theorem
Fisher's inequality
Union-closed sets conjecture |
https://en.wikipedia.org/wiki/Canid%20hybrid | Canid hybrids are the result of interbreeding between the species of the subfamily Caninae.
Genetic considerations
The wolf-like canids are a group of large carnivores that are genetically closely related because they all possess 78 chromosomes, arranged in 39 pairs and are karyologically indistinguishable from each other. The group includes the genera Canis, Cuon, Lupulella and Lycaon. The members are the domestic dog (C. lupus familiaris), gray wolf (C. lupus), dingo (C. lupus dingo), coyote (C. latrans), golden jackal (C. aureus), African wolf (C. lupaster), Ethiopian wolf (C. simensis), dhole (Cuon alpinus), black-backed jackal (Lupulella mesomelas), side-striped jackal (L. adusta) and African wild dog (Lycaon pictus). Newly proposed members include the red wolf (Canis rufus), and the eastern wolf (Canis lycaon), subject to a resolution of the dispute as to whether these constitute separate species in their own right or whether they are sub-species of the gray wolf. The members of Canis can potentially interbreed, however, it is believed that Cuon, Lupulella and Lycaon cannot breed with each other or with Canis. The Lupulella genus (the side-striped jackal and black-backed jackal), could theoretically interbreed with each other to produce fertile offspring, but a study of the maternal mitochondrial DNA of the black-backed jackal could find no evidence of genotypes from its most likely mate, the side-striped jackal, indicating that male black-backed jackals had not bred with their sister species.
When the differences in number and arrangement of chromosomes is too great, hybridization becomes less and less likely. Other members of the wider dog family, Canidae, such as South American canids, true foxes, bat-eared foxes, or raccoon dogs which diverged 7 to 10 million years ago, are less closely related to the wolf-like canids, have fewer chromosomes and cannot hybridize with them. (recently proven, partly incorrect, see pampas fox with dog below) For instance, t |
https://en.wikipedia.org/wiki/Isotachophoresis | Isotachophoresis (ITP) is a technique in analytical chemistry used for selective separation and concentration of ionic analytes. It is a form of electrophoresis; charged analytes are separated based on ionic mobility, a quantity which tells how fast an ion migrates through an electric field.
Overview
In conventional ITP separations, a discontinuous buffer system is used. The sample is introduced between a zone of fast leading electrolyte (LE) and a zone of slow terminating (or: trailing) electrolyte (TE). Usually, the LE and the TE have a common counterion, but the co-ions (having charges with the same sign as the analytes of interest) are different: the LE is defined by co-ions with high ionic mobility, while the TE is defined by co-ions with low ionic mobility. The analytes of interest have intermediate ionic mobility. Application of an electric potential results in a low electrical field in the leading electrolyte and a high electrical field in the terminating electrolyte. Analyte ions situated in the TE zone will migrate faster than the surrounding TE co-ions, while analyte ions situated in the LE will migrate slower; the result is that analytes are focused at the LE/TE interface.
ITP is a displacement method: focusing ions of a certain kind displace other ions. If present in sufficient amounts, focusing analyte ions can displace all electrolyte co-ions, reaching a plateau concentration. Multiple analytes with sufficiently different ionic mobilities will form multiple plateau zones. Indeed, plateau mode ITP separations are readily recognized by stairlike profiles, each plateau of the stair representing an electrolyte or analyte zone having (from LE to TE) increasing electric fields and decreasing conductivities. In peak mode ITP, analytes amounts are insufficient to reach plateau concentrations, such analytes will focus in sharp Gaussian-like peaks. In peak mode ITP, analyte peaks will strongly overlap, unless so-called spacer compounds are added with intermed |
https://en.wikipedia.org/wiki/Parapatric%20speciation | In parapatric speciation, two subpopulations of a species evolve reproductive isolation from one another while continuing to exchange genes. This mode of speciation has three distinguishing characteristics: 1) mating occurs non-randomly, 2) gene flow occurs unequally, and 3) populations exist in either continuous or discontinuous geographic ranges. This distribution pattern may be the result of unequal dispersal, incomplete geographical barriers, or divergent expressions of behavior, among other things. Parapatric speciation predicts that hybrid zones will often exist at the junction between the two populations.
In biogeography, the terms parapatric and parapatry are often used to describe the relationship between organisms whose ranges do not significantly overlap but are immediately adjacent to each other; they do not occur together except in a narrow contact zone. Parapatry is a geographical distribution opposed to sympatry (same area) and allopatry or peripatry (two similar cases of distinct areas).
Various "forms" of parapatry have been proposed and are discussed below. Coyne and Orr in Speciation categorise these forms into three groups: clinal (environmental gradients), "stepping-stone" (discrete populations), and stasipatric speciation in concordance with most of the parapatric speciation literature. Henceforth, the models are subdivided following a similar format.
Charles Darwin was the first to propose this mode of speciation. It was not until 1930, when Ronald Fisher published The Genetical Theory of Natural Selection where he outlined a verbal theoretical model of clinal speciation. In 1981, Joseph Felsenstein proposed an alternative, "discrete population" model (the "stepping-stone model). Since Darwin, a great deal of research has been conducted on parapatric speciation—concluding that its mechanisms are theoretically plausible, "and has most certainly occurred in nature".
Models
Mathematical models, laboratory studies, and observational evidence |
https://en.wikipedia.org/wiki/Massey%20product | In algebraic topology, the Massey product is a cohomology operation of higher order introduced in , which generalizes the cup product. The Massey product was created by William S. Massey, an American algebraic topologist.
Massey triple product
Let be elements of the cohomology algebra of a differential graded algebra . If , the Massey product is a subset of , where .
The Massey product is defined algebraically, by lifting the elements to equivalence classes of elements of , taking the Massey products of these, and then pushing down to cohomology. This may result in a well-defined cohomology class, or may result in indeterminacy.
Define to be . The cohomology class of an element of will be denoted by . The Massey triple product of three cohomology classes is defined by
The Massey product of three cohomology classes is not an element of , but a set of elements of , possibly empty and possibly containing more than one element. If have degrees , then the Massey product has degree , with the coming from the differential .
The Massey product is nonempty if the products and are both exact, in which case all its elements are in the same element of the quotient group
So the Massey product can be regarded as a function defined on triples of classes such that the product of the first or last two is zero, taking values in the above quotient group.
More casually, if the two pairwise products and both vanish in homology (), i.e., and for some chains and , then the triple product vanishes "for two different reasons" — it is the boundary of and (since and because elements of homology are cycles). The bounding chains and have indeterminacy, which disappears when one moves to homology, and since and have the same boundary, subtracting them (the sign convention is to correctly handle the grading) gives a cocycle (the boundary of the difference vanishes), and one thus obtains a well-defined element of cohomology — this step is analogous to defining t |
https://en.wikipedia.org/wiki/ATM%20%28computer%29 | The ATM Turbo (ru: "АТМ-ТУРБО"), also known simply as ATM (from ru: "Ассоциация Творческой Молодёжи", meaning "Association of Creative Youth") is a ZX Spectrum clone, developed in Moscow in 1991, by two firms, MicroArt and ATM.
It offers enhanced characteristics, compared to the original Spectrum, such as a , RAM, ROM, AY-8910 (two chips in upgraded models), 8-bit DAC, 8-bit 8-channel ADC, RS-232, parallel port, Beta Disk Interface, IDE interface, AT/XT keyboard, text mode (, , ), and three new graphics modes.
The ATM can be emulated in Unreal Speccy v0.27 and higher.
History
ATM was developed in 1991 based on the Pentagon, a ZX Spectrum clone popular in Russia. In 1992 an upgraded model was introduced, named ATM Turbo 2. Up to 1994 the computer was produced by ATM and MicroArt; later the firms separated and production ended.
In 2004 NedoPC from Moscow resumed production. New versions called ATM Turbo 2+ and ZX Evolution were introduced.
Characteristics
Graphics modes
For compatibility purposes, the original ZX Spectrum mode is available.
New graphics modes offer expanded abilities:
mode, with 2 out of 16 colors per 8x1 pixels. The Profi offers a similar mode, but the ATM can use the full set for both ink and paper.
mode with a raster mode (a two-pixel chunky mode, not planar like EGA). Two games for this mode were converted directly from PC: Prince of Persia and Goblins, and one from Sony PlayStation: Time Gal. Other games that use this mode exist, like Ball Quest, released in August, 2006.
Palette:
from a 64 color palette (6-bit RGB) can be set for all modes.
Operating systems
48K Sinclair BASIC, 128K Sinclair BASIC, TR-DOS, CP/M, iS-DOS, TASiS, DNA OS, Mr Gluk Reset Service.
Software
ATM Turbo
Virtual TR-DOS
Models
Many models exist. Models before version 6.00 are called ATM 1, later models are called ATM 2(2+) or ATM Turbo 2(2+) or simply Turbo 2+. A IDE interface is available since v6.00.JIO0UBH9BY8B9T7GVC6R (the latest model is 7.18 |
https://en.wikipedia.org/wiki/Faddeev%20equations | The Faddeev equations, named after their inventor Ludvig Faddeev, are equations that describe, at once, all the possible exchanges/interactions in a system of three particles in a fully quantum mechanical formulation. They can be solved iteratively.
In general, Faddeev equations need as input a potential that describes the interaction between two individual particles. It is also possible to introduce a term in the equation in order to take also three-body forces into account.
The Faddeev equations are the most often used non-perturbative formulations of the quantum-mechanical three-body problem.
Unlike the three body problem in classical mechanics, the quantum three body problem is uniformly soluble.
In nuclear physics, the off the energy shell nucleon-nucleon interaction has been studied by analyzing (n,2n) and (p,2p) reactions on deuterium targets, using the Faddeev Equations. The nucleon-nucleon interaction is expanded (approximated) as a series of separable potentials. The Coulomb interaction between two protons is a special problem, in that its expansion in separable potentials does not converge, but this is handled by matching the Faddeev solutions to long range Coulomb solutions, instead of to plane waves.
Separable potentials are interactions that do not preserve a particle's location. Ordinary local potentials can be expressed as sums of separable potentials. The physical nucleon-nucleon interaction, which involves exchange of mesons, is not expected to be either local or separable. |
https://en.wikipedia.org/wiki/Elmer%20FEM%20solver | Elmer is a computational tool for multi-physics problems. It has been developed by CSC in collaboration with Finnish universities, research laboratories and industry. Elmer FEM solver is free and open-source software, subject to the requirements of the GNU General Public License (GPL), version 2 or any later.
Elmer includes physical models of fluid dynamics, structural mechanics, electromagnetics, heat transfer and acoustics, for example. These are described by partial differential equations which Elmer solves by the Finite Element Method (FEM).
Elmer comprises several different parts:
ElmerGrid – A mesh conversion tool, which can be used to convert differing mesh formats into Elmer-suitable meshes.
ElmerGUI – A graphical interface which can be used on an existing mesh to assign physical models, this generates a "case file" which describes the problem to be solved. Does not show the whole ElmerSolver functionality in GUI.
ElmerSolver – The numerical solver which performs the finite element calculations, using the mesh and case files.
ElmerPost – A post-processing/visualisation module. (Development stopped in favour of other post-processing tools such as ParaView, VisIt, etc.)
The different parts of Elmer software may be used independently. Whilst the main module is the ElmerSolver tool, which includes many sophisticated features for physical model solving, the additional components are required to create a full workflow. For pre- and post-processing other tools, such as Paraview can be used to visualise the output.
The software runs on Unix and Windows platforms and can be compiled on a large variety of compilers, using the CMake building tool. The solver can also be used in a multi-host parallel mode on platforms that support MPI. Elmer's parallelisation capability is one of the strongest sides of this solver.
External links
See also
Finite Element Method
List of finite element packages |
https://en.wikipedia.org/wiki/Quantum%20register | In quantum computing, a quantum register is a system comprising multiple qubits. It is the quantum analogue of the classical processor register. Quantum computers perform calculations by manipulating qubits within a quantum register.
Definition
It is usually assumed that the register consists of qubits. It is also generally assumed that registers are not density matrices, but that they are pure, although the definition of "register" can be extended to density matrices.
An size quantum register is a quantum system comprising pure qubits.
The Hilbert space, , in which the data is stored in a quantum register is given by where is the tensor product.
The number of dimensions of the Hilbert spaces depends on what kind of quantum systems the register is composed of. Qubits are 2-dimensional complex spaces (), while qutrits are 3-dimensional complex spaces (), et.c. For a register composed of N number of d-dimensional (or d-level) quantum systems we have the Hilbert space
The registers quantum state can in the bra-ket notation be written The values are probability amplitudes. Because of the Born rule and the 2nd axiom of probability theory, so the possible state space of the register is the surface of the unit sphere in
Examples:
The quantum state vector of a 5-qubit register is a unit vector in
A register of four qutrits similarly is a unit vector in
Quantum vs. classical register
First, there's a conceptual difference between the quantum and classical register.
An size classical register refers to an array of flip flops. An size quantum register is merely a collection of qubits.
Moreover, while an size classical register is able to store a single value of the possibilities spanned by classical pure bits, a quantum register is able to store all possibilities spanned by quantum pure qubits at the same time.
For example, consider a 2-bit-wide register. A classical register is able to store only one of the possible values represented by 2 |
https://en.wikipedia.org/wiki/Airhitch | Airhitch was a user-run system for hitchhiking on commercial airliners. It was started by Robert Segelbaum in 1969. People, who travel in this way, generally refer to themselves as Airhitchers. Most airhitchers fly between the United States and Western Europe. Before Airhitch migrated to internet based communication in the 1990s, it operated out of North American offices including New York, Los Angeles (Santa Monica), San Francisco, Seattle, Montreal, and Vancouver, and numerous European cities including Paris, Amsterdam, Berlin, Bonn, and Rome. Airhitch is a non-commercial system/method/process. Today, virtually, all exchange of Airhitch information takes place in an AIM chat room. In the chat room, Airhitchers use their real names, while the staff use screen names such as Airhitch01, and Airhitch08.
Since 2006, the cost and availability of "Airhitchable" flights has been questionable. Before the website (airhitch.org) and business went defunct in 2009, the majority of "AHers", opt to help each other find conventional airfare to their destinations.
The Airhitching process
Registration: Airhitchers formally commit to participation in the Airhitch system by sending an online registration to the staff.
Flight-Briefing: With the guidance of the staff, Airhitchers explore the best possibilities for catching rides on flights and the procedural mechanics of how to take advantage of them.
Decision: Airhitchers decide which flight they will attempt to board.
Boarding: Airhitchers go to the airport and attempt to board the aircraft.
Controversy
Around the year 2000, there were two websites with very similar names claiming the name Air Hitch, and both denied any affiliation with the other. At the time, the system used prepaid vouchers. Due to the similar websites and general nature of online reviews, it was not clear which website was part of the legitimate airhitch system.
Some online user reviews talked of invalid vouchers and scam tactics. Including invalid mailin |
https://en.wikipedia.org/wiki/Dunbar%27s%20number | Dunbar's number is a suggested cognitive limit to the number of people with whom one can maintain stable social relationships—relationships in which an individual knows who each person is and how each person relates to every other person.
This number was first proposed in the 1990s by British anthropologist Robin Dunbar, who found a correlation between primate brain size and average social group size. By using the average human brain size and extrapolating from the results of primates, he proposed that humans can comfortably maintain 150 stable relationships. There is some evidence that brain structure predicts the number of friends one has, though causality remains to be seen.
Dunbar explained the principle informally as "the number of people you would not feel embarrassed about joining uninvited for a drink if you happened to bump into them in a bar." Dunbar theorised that "this limit is a direct function of relative neocortex size, and that this, in turn, limits group size [...] the limit imposed by neocortical processing capacity is simply on the number of individuals with whom a stable inter-personal relationship can be maintained". On the periphery, the number also includes past colleagues, such as high school friends, with whom a person would want to reacquaint themselves if they met again. Proponents assert that numbers larger than this generally require more restrictive rules, laws, and enforced norms to maintain a stable, cohesive group. It has been proposed to lie between 100 and 250, with a commonly used value of 150.
Research background
Primatologists have noted that, owing to their highly social nature, primates must maintain personal contact with the other members of their social group, usually through social grooming. Such social groups function as protective cliques within the physical groups in which the primates live. The number of social group members a primate can track appears to be limited by the volume of the neocortex. This suggests tha |
https://en.wikipedia.org/wiki/Biotech%20Sweden | Biotech Sweden was a Swedish tabloid magazine about and for the Scandinavian life science and biotech industry.
History and profile
Biotech Sweden was first published on 9 April 2002 by IDG Sweden, a subsidiary of IDG. It was sister publication of Bio-IT World. At its initial phase Biotech Sweden was published seven times a year. Then it began to be published 11 times per year. The readers were mainly people working in the biotechnology medtech and pharma industry of the Nordic countries. It also carried the largest life science web news service of the Nordic countries, www.lifesciencesweden.se, with four newsletter distributed three times a week, subscription free-of-charge. On the website the magazine provided daily news in Swedish and a weekly news-letter covering life science news of the Nordic countries, plus also access to The Scandinavian Life Science Industry Guide, a database of all life science, medtech and labtech companies of Scandinavia. Life Science Sweden is also official media partner of Sweden Bio.
The editor-in-chiefs included Ingrid Heath, Jörgen Lindqvist, Ingrid Helander and Loth Hammar.
In 2012, the magazine changed its name to Life Science Sweden and in 2013 it was sold to Mentor Communications AB. |
https://en.wikipedia.org/wiki/Precision%20rectifier | The precision rectifier is a configuration obtained with an operational amplifier in order to have a circuit behave like an ideal diode and rectifier. It is very useful for high-precision signal processing. With the help of a precision rectifier the high-precision signal processing can be done very easily.
The op-amp-based precision rectifier should not be confused with the power MOSFET-based active rectification ideal diode.
Basic circuit
The basic circuit implementing such a feature is shown on the right, where can be any load. When the input voltage is negative, there is a negative voltage on the diode, so it works like an open circuit, no current flows through the load, and the output voltage is zero. When the input is positive, it is amplified by the operational amplifier, which switches the diode on. Current flows through the load and, because of the feedback, the output voltage is equal to the input voltage.
The actual threshold of the super diode is very close to zero, but is not zero. It equals the actual threshold of the diode, divided by the gain of the operational amplifier.
This basic configuration has a problem, so it is not commonly used. When the input becomes (even slightly) negative, the operational amplifier runs open-loop, as there is no feedback signal through the diode. For a typical operational amplifier with high open-loop gain, the output saturates. If the input then becomes positive again, the op-amp has to get out of the saturated state before positive amplification can take place again. This change generates some ringing and takes some time, greatly reducing the frequency response of the circuit.
Improved circuit
An alternative version is given on the right. In this case, when the input is greater than zero, D1 is off, and D2 is on, so the output is zero because the other end of is connected to the virtual ground and there is no current through . When the input is less than zero, D1 is on and D2 is off, so the output is like th |
https://en.wikipedia.org/wiki/Negative%20impedance%20converter | The negative impedance converter (NIC) is an active circuit which injects energy into circuits in contrast to an ordinary load that consumes energy from them. This is achieved by adding or subtracting excessive varying voltage in series to the voltage drop across an equivalent positive impedance. This reverses the voltage polarity or the current direction of the port and introduces a phase shift of 180° (inversion) between the voltage and the current for any signal generator. The two versions obtained are accordingly a negative impedance converter with voltage inversion (VNIC) and a negative impedance converter with current inversion (INIC). The basic circuit of an INIC and its analysis is shown below.
Basic circuit and analysis
INIC is a non-inverting amplifier (the op-amp and the voltage divider , on the figure) with a resistor () connected between its output and input. The op-amp output voltage is
The current going from the operational amplifier output through resistor toward the source is , and
So the input experiences an opposing current that is proportional to , and the circuit acts like a resistor with negative resistance
In general, elements , , and need not be pure resistances (i.e., they may be capacitors, inductors, or impedance networks).
Application
By using an NIC as a negative resistor, it is possible to let a real generator behave (almost) like an ideal generator, (i.e., the magnitude of the current or of the voltage generated does not depend on the load).
An example for a current source is shown in the figure on the right. The current generator and the resistor within the dotted line is the Norton representation of a circuit comprising a real generator and is its internal resistance. If an INIC is placed in parallel to that internal resistance, and the INIC has the same magnitude but inverted resistance value, there will be and in parallel. Hence, the equivalent resistance is
That is, the combination of the real generator and the I |
https://en.wikipedia.org/wiki/Bel%20decomposition | In semi-Riemannian geometry, the Bel decomposition, taken with respect to a specific timelike congruence, is a way of breaking up the Riemann tensor of a pseudo-Riemannian manifold into lower order tensors with properties similar to the electric field and magnetic field. Such a decomposition was partially described by Alphonse Matte in 1953 and by Lluis Bel in 1958.
This decomposition is particularly important in general relativity. This is the case of four-dimensional Lorentzian manifolds, for which there are only three pieces with simple properties and individual physical interpretations.
Decomposition of the Riemann tensor
In four dimensions the Bel decomposition of the Riemann tensor, with respect to a timelike unit vector field , not necessarily geodesic or hypersurface orthogonal, consists of three pieces:
the electrogravitic tensor
Also known as the tidal tensor. It can be physically interpreted as giving the tidal stresses on small bits of a material object (which may also be acted upon by other physical forces), or the tidal accelerations of a small cloud of test particles in a vacuum solution or electrovacuum solution.
the magnetogravitic tensor
Can be interpreted physically as a specifying possible spin-spin forces on spinning bits of matter, such as spinning test particles.
the topogravitic tensor
Can be interpreted as representing the sectional curvatures for the spatial part of a frame field.
Because these are all transverse (i.e. projected to the spatial hyperplane elements orthogonal to our timelike unit vector field), they can be represented as linear operators on three-dimensional vectors, or as three-by-three real matrices. They are respectively symmetric, traceless, and symmetric (6,8,6 linearly independent components, for a total of 20). If we write these operators as E, B, L respectively, the principal invariants of the Riemann tensor are obtained as follows:
is the trace of E2 + L2 - 2 B BT,
is the trace of B ( E - L ),
|
https://en.wikipedia.org/wiki/Ingredient | In a general sense, an ingredient is a substance which forms part of a mixture. In cooking, recipes specify which ingredients are used to prepare a dish. Many commercial products contain secret ingredients purported to make them better than competing products. In the pharmaceutical industry, an active ingredient is the ingredient in a formulation which invokes biological activity.
National laws usually require prepared food products to display a list of ingredients and specifically require that certain additives be listed. Law typically requires that ingredients be listed according to their relative weight within the product.
Artificial ingredient
An artificial ingredient usually refers to an ingredient which is artificial or human-made, such as:
Artificial flavour
Food additive
Food colouring
Preservative
Sugar substitute, artificial sweetener
See also
Fake food
Bill of materials
Software Bill of Materials
Active Ingredient
Secret Ingredient |
https://en.wikipedia.org/wiki/Polysorbate | Polysorbates are a class of emulsifiers used in some pharmaceuticals and food preparation. They are commonly used in oral and topical pharmaceutical dosage forms. They are also often used in cosmetics to solubilize essential oils into water-based products. Polysorbates are oily liquids derived from ethoxylated sorbitan (a derivative of sorbitol) esterified with fatty acids. Common brand names for polysorbates include Kolliphor, Scattics, Alkest, Canarcel, Tween, and Kotilen.
Examples
Polysorbate 20 (polyoxyethylene (20) sorbitan monolaurate)
Polysorbate 40 (polyoxyethylene (20) sorbitan monopalmitate)
Polysorbate 60 (polyoxyethylene (20) sorbitan monostearate)
Polysorbate 80 (polyoxyethylene (20) sorbitan monooleate)
The number following the 'polysorbate' part is related to the type of major fatty acid associated with the molecule. Monolaurate is indicated by 20, monopalmitate is indicated by 40, monostearate by 60, and monooleate by 80. The number 20 following the 'polyoxyethylene' part refers to the total number of oxyethylene (–CH2CH2O–) groups found in the molecule.
See also
Sorbitan monolaurate
Sorbitan monostearate
Sorbitan tristearate
Sorbitan monooleate |
https://en.wikipedia.org/wiki/Transketolase | Transketolase (abbreviated as TK) is an enzyme that, in humans, is encoded by the TKT gene. It participates in both the pentose phosphate pathway in all organisms and the Calvin cycle of photosynthesis. Transketolase catalyzes two important reactions, which operate in opposite directions in these two pathways. In the first reaction of the non-oxidative pentose phosphate pathway, the cofactor thiamine diphosphate accepts a 2-carbon fragment from a 5-carbon ketose (D-xylulose-5-P), then transfers this fragment to a 5-carbon aldose (D-ribose-5-P) to form a 7-carbon ketose (sedoheptulose-7-P). The abstraction of two carbons from D-xylulose-5-P yields the 3-carbon aldose glyceraldehyde-3-P. In the Calvin cycle, transketolase catalyzes the reverse reaction, the conversion of sedoheptulose-7-P and glyceraldehyde-3-P to pentoses, the aldose D-ribose-5-P and the ketose D-xylulose-5-P.
The second reaction catalyzed by transketolase in the pentose phosphate pathway involves the same thiamine diphosphate-mediated transfer of a 2-carbon fragment from D-xylulose-5-P to the aldose erythrose-4-phosphate, affording fructose 6-phosphate and glyceraldehyde-3-P. Again, in the Calvin cycle exactly the same reaction occurs, but in the opposite direction. Moreover, in the Calvin cycle this is the first reaction catalyzed by transketolase, rather than the second.
In mammals, transketolase connects the pentose phosphate pathway to glycolysis, feeding excess sugar phosphates into the main carbohydrate metabolic pathways. Its presence is necessary for the production of NADPH, especially in tissues actively engaged in biosyntheses, such as fatty acid synthesis by the liver and mammary glands, and for steroid synthesis by the liver and adrenal glands. Thiamine diphosphate is an essential cofactor, along with calcium.
Transketolase is abundantly expressed in the mammalian cornea by the stromal keratocytes and epithelial cells and is reputed to be one of the corneal crystallins.
Species distr |
https://en.wikipedia.org/wiki/Test%20particle | In physical theories, a test particle, or test charge, is an idealized model of an object whose physical properties (usually mass, charge, or size) are assumed to be negligible except for the property being studied, which is considered to be insufficient to alter the behavior of the rest of the system. The concept of a test particle often simplifies problems, and can provide a good approximation for physical phenomena. In addition to its uses in the simplification of the dynamics of a system in particular limits, it is also used as a diagnostic in computer simulations of physical processes.
Classical gravity
The easiest case for the application of a test particle arises in Newtonian gravity. The general expression for the gravitational force between any two point masses and is:
,
where and represent the position of each particle in space. In the general solution for this equation, both masses rotate around their center of mass R, in this specific case:
.
In the case where one of the masses is much larger than the other (), one can assume that the smaller mass moves as a test particle in a gravitational field generated by the larger mass, which does not accelerate. We can define the gravitational field as
,
with as the distance between the massive object and the test particle, and is the unit vector in the direction going from the massive object to the test mass. Newton's second law of motion of the smaller mass reduces to
,
and thus only contains one variable, for which the solution can be calculated more easily. This approach gives very good approximations for many practical problems, e.g. the orbits of satellites, whose mass is relatively small compared to that of the Earth.
Electrostatics
In simulations with electric fields the most important characteristics of a test particle is its electric charge and its mass. In this situation it is often referred to as a test charge.
Similar to the case of classical gravitation, the electric field created |
https://en.wikipedia.org/wiki/Herbert%20Sichel | Herbert Sichel (1915–1995) was a statistician who made great advances in the areas of both theoretical and applied statistics.
He developed the Sichel-t estimator for the log-normal distribution's t-statistic. He also made great leaps in the area of the generalized inverse Gaussian distribution, the mixture of which with the Poisson distribution became known as the Sichel distribution.
Dr Sichel pioneered the science of geostatistics with Danie Krige in the early 1950s. Sichel also was well recognised in the field of statistical linguistics.
He established the Operational Research Bureau in 1952. He was appointed as professor in Statistics and Operations Research in the Graduate Business School of the University of the Witwatersrand. He has been recognized as "one of the grand old men of the SA Statistical Association". In 1958 he was elected as a Fellow of the American Statistical Association.
The Herbert Sichel medal was established in 1997 and is awarded annually to the best statistics paper published in a South African journal in the previous year. |
https://en.wikipedia.org/wiki/Oil%20analysis | Oil analysis (OA) is the laboratory analysis of a lubricant's properties, suspended contaminants, and wear debris. OA is performed during routine predictive maintenance to provide meaningful and accurate information on lubricant and machine condition. By tracking oil analysis sample results over the life of a particular machine, trends can be established which can help eliminate costly repairs. The study of wear in machinery is called tribology. Tribologists often perform or interpret oil analysis data.
OA can be divided into three categories:
analysis of oil properties including those of the base oil and its additives,
analysis of contaminants,
analysis of wear debris from machinery,
Oil sampling
Oil sampling is a procedure for collecting a volume of fluid from lubricated or hydraulic machinery for the purpose of oil analysis. Much like collecting forensic evidence at a crime scene, when collecting an oil sample, it is important to ensure that procedures are used to minimize disturbance of the sample during and after the sampling process. Oil samples are typically drawn into a small, clean bottle which is sealed and sent to a laboratory for analysis.
History
OA was first used after World War II by the US railroad industry to monitor the health of locomotives. In 1946 the Denver and Rio Grande Railroad's research laboratory successfully detected diesel engine problems through wear metal analysis of used oils. A key factor in their success was the development of the spectrograph, an instrument which replaced several wet chemical methods for detecting and measuring individual chemical element such as iron or copper. This practice was soon accepted and used extensively throughout the railroad industry.
By 1955 OA had matured to the point that the United States Bureau of Naval Weapons began a major research program to adopt wear metal analysis for use in aircraft component failure prediction. These studies formed the basis for a Joint Oil Analysis Program (JOAP) |
https://en.wikipedia.org/wiki/Gr%C3%A9goire%20de%20Saint-Vincent | Grégoire de Saint-Vincent - in Latin : Gregorius a Sancto Vincentio, in Dutch : Gregorius van St-Vincent - (8 September 1584 Bruges – 5 June 1667 Ghent) was a Flemish Jesuit and mathematician. He is remembered for his work on quadrature of the hyperbola.
Grégoire gave the "clearest early account of the summation of geometric series." He also resolved Zeno's paradox by showing that the time intervals involved formed a geometric progression and thus had a finite sum.
Life
Gregoire was born in Bruges 8 September 1584. After reading philosophy in Douai, he entered the Society of Jesus 21 October 1605. His talent was recognized by Christopher Clavius in Rome. Gregoire was sent to Louvain in 1612, and was ordained a priest 23 March 1613. Gregoire began teaching in association with François d'Aguilon in Antwerp from 1617 to 20. Moving to Louvain in 1621, he taught mathematics there until 1625. That year he became obsessed with squaring the circle and requested permission from Mutio Vitelleschi to publish his method. But Vitelleschi deferred to Christoph Grienberger, the mathematician in Rome.
On 9 September 1625, Gregoire set out for Rome to confer with Grienberger, but without avail. He returned to the Netherlands in 1627, and the following year was sent to Prague to serve in the house of Emperor Ferdinand II. After an attack of apoplexy, he was assisted there by Theodorus Moretus. When the Saxons raided Prague in 1631, Gregoire left and some of his manuscripts were lost in the mayhem. Others were returned to him in 1641 through Rodericus de Arriaga.
From 1632 Gregoire resided with The Society in Ghent and served as a mathematics teacher.
The mathematical thinking of Sancto Vincentio underwent a clear evolution during his stay in Antwerp. Starting from the problem of trisection of the angle and the determination of the two mean proportional, he made use of infinite series, the logarithmic property of the hyperbola, limits, and the related method of exhaustion. Sancto |
https://en.wikipedia.org/wiki/Curvature%20invariant | In Riemannian geometry and pseudo-Riemannian geometry, curvature invariants are scalar quantities constructed from tensors that represent curvature. These tensors are usually the Riemann tensor, the Weyl tensor, the Ricci tensor and tensors formed from these by the operations of taking dual contractions and covariant differentiations.
Types of curvature invariants
The invariants most often considered are polynomial invariants. These are polynomials constructed from contractions such as traces. Second degree examples are called quadratic invariants, and so forth. Invariants constructed using covariant derivatives up to order n are called n-th order differential invariants.
The Riemann tensor is a multilinear operator of fourth rank acting on tangent vectors. However, it can also be considered a linear operator acting on bivectors, and as such it has a characteristic polynomial, whose coefficients and roots (eigenvalues) are polynomial scalar invariants.
Physical applications
In metric theories of gravitation such as general relativity, curvature scalars play an important role in telling distinct spacetimes apart.
Two of the most basic curvature invariants in general relativity are the Kretschmann scalar
and the Chern–Pontryagin scalar,
These are analogous to two familiar quadratic invariants of the electromagnetic field tensor in classical electromagnetism.
An important unsolved problem in general relativity is to give a basis (and any syzygies) for the zero-th order invariants of the Riemann tensor.
They have limitations because many distinct spacetimes cannot be distinguished on this basis. In particular, so called VSI spacetimes (including pp-waves as well as some other Petrov type N and III spacetimes) cannot be distinguished from Minkowski spacetime using any number of polynomial curvature invariants (of any order).
See also
Cartan–Karlhede algorithm
Carminati–McLenaghan invariants
Curvature invariant (general relativity)
Ricci decomposition |
https://en.wikipedia.org/wiki/Cartan%E2%80%93Karlhede%20algorithm | The Cartan–Karlhede algorithm is a procedure for completely classifying and comparing Riemannian manifolds. Given two Riemannian manifolds of the same dimension, it is not always obvious whether they are locally isometric. Élie Cartan, using his exterior calculus with his method of moving frames, showed that it is always possible to compare the manifolds. Carl Brans developed the method further, and the first practical implementation was presented by in 1980.
The main strategy of the algorithm is to take covariant derivatives of the Riemann tensor. Cartan showed that in n dimensions at most n(n+1)/2 differentiations suffice. If the Riemann tensor and its derivatives of the one manifold are algebraically compatible with the other, then the two manifolds are isometric. The Cartan–Karlhede algorithm therefore acts as a kind of generalization of the Petrov classification.
The potentially large number of derivatives can be computationally prohibitive. The algorithm was implemented in an early symbolic computation engine, SHEEP, but the size of the computations proved too challenging for early computer systems to handle. For most problems considered, far fewer derivatives than the maximum are actually required, and the algorithm is more manageable on modern computers. On the other hand, no publicly available version exists in more modern software.
Physical applications
The Cartan–Karlhede algorithm has important applications in general relativity. One reason for this is that the simpler notion of curvature invariants fails to distinguish spacetimes as well as they distinguish Riemannian manifolds. This difference in behavior is due ultimately to the fact that spacetimes have isotropy subgroups which are subgroups of the Lorentz group SO+(1,3), which is a noncompact Lie group, while four-dimensional Riemannian manifolds (i.e., with positive definite metric tensor), have isotropy groups which are subgroups of the compact Lie group SO(4).
In 4 dimensions, K |
https://en.wikipedia.org/wiki/Parameterized%20post-Newtonian%20formalism | In physics, precisely in the study of the theory of general relativity and many alternatives to it, the post-Newtonian formalism is a calculational tool that expresses Einstein's (nonlinear) equations of gravity in terms of the lowest-order deviations from Newton's law of universal gravitation. This allows approximations to Einstein's equations to be made in the case of weak fields. Higher-order terms can be added to increase accuracy, but for strong fields, it may be preferable to solve the complete equations numerically. Some of these post-Newtonian approximations are expansions in a small parameter, which is the ratio of the velocity of the matter forming the gravitational field to the speed of light, which in this case is better called the speed of gravity. In the limit, when the fundamental speed of gravity becomes infinite, the post-Newtonian expansion reduces to Newton's law of gravity.
The parameterized post-Newtonian formalism or PPN formalism, is a version of this formulation that explicitly details the parameters in which a general theory of gravity can differ from Newtonian gravity. It is used as a tool to compare Newtonian and Einsteinian gravity in the limit in which the gravitational field is weak and generated by objects moving slowly compared to the speed of light. In general, PPN formalism can be applied to all metric theories of gravitation in which all bodies satisfy the Einstein equivalence principle (EEP). The speed of light remains constant in PPN formalism and it assumes that the metric tensor is always symmetric.
History
The earliest parameterizations of the post-Newtonian approximation were performed by Sir Arthur Stanley Eddington in 1922. However, they dealt solely with the vacuum gravitational field outside an isolated spherical body. Ken Nordtvedt (1968, 1969) expanded this to include seven parameters in papers published in 1968 and 1969. Clifford Martin Will introduced a stressed, continuous matter description of celestial bodies in |
https://en.wikipedia.org/wiki/Hole%20argument | In general relativity, the hole argument is an apparent paradox that much troubled Albert Einstein while developing his famous field equations.
Some philosophers of physics take the argument to raise a problem for manifold substantialism, a doctrine that the manifold of events in spacetime is a "substance" which exists independently of the metric field defined on it or the matter within it. Other philosophers and physicists disagree with this interpretation, and view the argument as a confusion about gauge invariance and gauge fixing instead.
Einstein's hole argument
In a usual field equation, knowing the source of the field, and the boundary conditions, determines the field everywhere. For example, if we are given the current and charge density and appropriate boundary conditions, Maxwell's equations determine the electric and magnetic fields. They do not determine the vector potential though, because the vector potential depends on an arbitrary choice of gauge.
Einstein noticed that if the equations of gravity are generally covariant, then the metric cannot be determined uniquely by its sources as a function of the coordinates of spacetime. As an example: consider a gravitational source, such as the Sun. Then there is some gravitational field described by a metric g(r). Now perform a coordinate transformation r r' where r' is the same as r for points which are inside the Sun but r' is different from r outside the Sun. The coordinate description of the interior of the Sun is unaffected by the transformation, but the functional form of the metric g' for the new coordinate values outside the Sun is changed. Due to the general covariance of the field equations, this transformed metric g' is also a solution in the untransformed coordinate system.
This means that one source, the Sun, can be the source of many seemingly different metrics. The resolution is immediate: any two fields which only differ by such a "hole" transformation are physically equivalent, just as t |
https://en.wikipedia.org/wiki/The%20New%20Dinosaurs | The New Dinosaurs: An Alternative Evolution is a 1988 speculative evolution book written by Scottish geologist and palaeontologist Dougal Dixon and illustrated by several illustrators including Amanda Barlow, Peter Barrett, John Butler, Jeane Colville, Anthony Duke, Andy Farmer, Lee Gibbons, Steve Holden, Philip Hood, Martin Knowelden, Sean Milne, Denys Ovenden and Joyce Tuhill. The book also features a foreword by Desmond Morris. The New Dinosaurs explores a hypothetical alternate Earth, complete with animals and ecosystems, where the Cretaceous-Paleogene extinction event never occurred, leaving non-avian dinosaurs and other Mesozoic animals an additional 65 million years to evolve and adapt over the course of the Cenozoic to the present day.
The New Dinosaurs is Dixon's second work on speculative evolution, following After Man (1981). Like After Man, The New Dinosaurs uses its own fictional setting and hypothetical wildlife to explain natural processes with fictitious examples, in this case the concept of zoogeography and biogeographic realms. It was followed by another speculative evolution work by Dixon in 1990, Man After Man.
Although criticised by some palaeontologists upon its release, several of Dixon's hypothetical dinosaurs bear a coincidental resemblance in both appearance and behaviour to dinosaurs that were discovered after the book's publication. As a general example, many of the fictional dinosaurs are depicted with feathers, something that was not yet widely accepted when the book was written.
Summary
The New Dinosaurs explores an imagined alternate version of the present-day Earth as Dixon imagines it would have been if the Cretaceous-Paleogene extinction event had never occurred. As in Dixon's previous work, After Man, ecology and evolutionary theory are applied to create believable creatures, all of which have their own binomial names and text describing their behaviour and interactions with other contemporary animals. Most of these animals r |
https://en.wikipedia.org/wiki/Wireless%20security | Wireless security is the prevention of unauthorized access or damage to computers or data using wireless networks, which include Wi-Fi networks. The term may also refer to the protection of the wireless network itself from adversaries seeking to damage the confidentiality, integrity, or availability of the network. The most common type is Wi-Fi security, which includes Wired Equivalent Privacy (WEP) and Wi-Fi Protected Access (WPA). WEP is an old IEEE 802.11 standard from 1997. It is a notoriously weak security standard: the password it uses can often be cracked in a few minutes with a basic laptop computer and widely available software tools. WEP was superseded in 2003 by WPA, a quick alternative at the time to improve security over WEP. The current standard is WPA2; some hardware cannot support WPA2 without firmware upgrade or replacement. WPA2 uses an encryption device that encrypts the network with a 256-bit key; the longer key length improves security over WEP. Enterprises often enforce security using a certificate-based system to authenticate the connecting device, following the standard 802.11X.
In January 2018, the Wi-Fi Alliance announced WPA3 as a replacement to WPA2. Certification began in June 2018, and WPA3 support has been mandatory for devices which bear the "Wi-Fi CERTIFIED™" logo since July 2020.
Many laptop computers have wireless cards pre-installed. The ability to enter a network while mobile has great benefits. However, wireless networking is prone to some security issues. Hackers have found wireless networks relatively easy to break into, and even use wireless technology to hack into wired networks. As a result, it is very important that enterprises define effective wireless security policies that guard against unauthorized access to important resources. Wireless Intrusion Prevention Systems (WIPS) or Wireless Intrusion Detection Systems (WIDS) are commonly used to enforce wireless security policies.
The risks to users of wireless technology |
https://en.wikipedia.org/wiki/Thexder | is a run and gun video game from Game Arts, originally released for the NEC PC-8801 in 1985. It was ported to many systems, including the Famicom.
Gameplay
In Thexder, the player controls a fighter robot that is able to transform into a jet and shoot lasers.
Release
The game was originally released in 1985 for the NEC PC-8801 platform in Japan. Game Arts licensed Thexder to Square in order to develop a conversion for the Nintendo Entertainment System (NES) game console. In 1987, Game Arts also developed a Thexder conversion for the MSX platform. The game was licensed to Sierra Entertainment for release in the United States. Sierra ported the game to multiple platforms, including the IBM PC, Tandy Color Computer 3, Apple II, Apple IIGS, Apple Macintosh, and Tandy 1000. In 1988, Activision released the game in Europe on the Commodore Amiga.
Reception
Thexder quickly became a best-selling hit, selling over 500,000 copies in Japan by 1987. The PC-8801 platform was only popular in Japan and, despite home market success, Thexder garnered little attention abroad initially. With the conversion for the MSX (the best-selling platform in Brazil and many Eastern European countries), it became an international hit. It became the company's best-selling title of 1987. By 1990, the game had sold over one million copies worldwide.
Compute! praised the Apple IIGS version of Thexder as the computer's "first true arcade game" with "excellent play value for your dollar". In 1988, The Games Machine gave the Amiga version a 74% score. In 1991, Dragon gave the Macintosh and PC/MS-DOS versions of the game each 4 out of 5 stars. The game went on to sell over one million copies worldwide, becoming Game Arts' biggest-selling title of 1987. Thexder is considered an important breakthrough title for the run-and-gun shooter game genre, paving the way for titles such as Contra and Metal Slug.
Other games in the series |
https://en.wikipedia.org/wiki/Via%20%28electronics%29 | A via (Latin, 'path' or 'way') is an electrical connection between two or more metal layers, and are commonly used in printed circuit boards (PCB). Essentially a via is a small drilled hole that goes through two or more adjacent layers; the hole is plated with metal (often copper) that forms an electrical connection through the insulating layers.
Vias are important for PCB manufacturing. This is because the vias are drilled with certain tolerances and may be fabricated off their designated locations, so some allowance for errors in drill position must be made prior to manufacturing or else the manufacturing yield can decrease due to non-conforming boards (according to some reference standard) or even due to failing boards. In addition, regular through hole vias are considered fragile structures as they are long and narrow; the manufacturer must ensure that the vias are plated properly throughout the barrel and this in turn causes several processing steps.
In printed circuit boards
In printed circuit board (PCB) design, a via consists of two pads in corresponding positions on different copper layers of the board, that are electrically connected by a hole through the board. The hole is made conductive by electroplating, or is lined with a tube or a rivet. High-density multilayer PCBs may have microvias: blind vias are exposed only on one side of the board, while buried vias connect internal layers without being exposed on either surface. Thermal vias carry heat away from power devices and are typically used in arrays of about a dozen.
A via consists of:
Barrel — conductive tube filling the drilled hole
Pad — connects each end of the barrel to the component, plane, or trace
Antipad — clearance hole between barrel and metal layer to which it is not connected
A via, sometimes called PTV or plated-through-via, should not be confused with a plated through hole (PTH). Via is used as an interconnection between copper layers on a PCB while the PTH is generally made l |
https://en.wikipedia.org/wiki/Ursid%20hybrid | An ursid hybrid is an animal with parents from two different species or subspecies of the bear family (Ursidae). Species and subspecies of bear known to have produced offspring with another bear species or subspecies include American black bears, grizzly bears, and polar bears, all of which are members of the genus Ursus. Bears not included in Ursus, such as the giant panda, are expected to be unable to produce hybrids with other bears. The giant panda bear belongs to the genus Ailuropoda.
Note all of the confirmed hybrids listed here have been in captivity (except grizzly × polar bear), but suspected hybrids have been found in the wild.
A recent study found genetic evidence of multiple instances and species combinations where genetic material has passed the species boundary in bears (a process called introgression by geneticists). Specifically, species with evidence of past intermingling were (1) brown bear and American black bear, (2) brown bear and polar bear, (3) American black bear and Asian black bear. Overall, this study shows that evolution in the bear family (Ursidae) has not been strictly bifurcating, but instead showed complex evolutionary relationships.
All the Ursinae species (i.e., all bears except the giant panda and the spectacled bear) appear able to crossbreed.
Brown × black bear hybrids
In 1859, a black bear and a European brown bear were bred together in the London Zoological Gardens, but the three cubs did not reach maturity. In The Variation of Animals and Plants Under Domestication Darwin noted:
In the nine-year Report it is stated that the bears had been seen in the Zoological Gardens to couple freely, but previously to 1848 most had rarely conceived. In the Reports published since this date three species have produced young (hybrids in one case), ...
A bear shot in autumn 1986 in Alaska was thought by some to be a grizzly × black bear hybrid, due to its unusually large size and its proportionately larger braincase and skull. DNA test |
https://en.wikipedia.org/wiki/Robert%20Brunner | Robert Brunner (born 1958) is an American industrial designer. Brunner was the Director of Industrial Design for Apple Computer from 1989 to 1996, and is a founder and current partner at Ammunition Design Group.
Biography
Brunner received a Bachelor of Science degree in Industrial Design from San José State University in 1981.
After working as a designer and project manager at several high technology companies, Brunner went on to co-found Lunar Design in 1984. In 1989, Brunner accepted the position of Director of Industrial Design at Apple Computer, where he provided design and direction for all Apple product lines, including the PowerBook. He was succeeded by Jonathan Ive in 1997. Brunner claims that while with Apple, he hired Ive three times.
In January 1996, he became a partner in the San Francisco office of Pentagram. In 2006, Brunner partnered Alex Siow, founder of San Francisco-based Zephyr Ventilation, to launch outdoor grill design firm Fuego. Emblematic of his relationship with Siow, he designed the Arc Collection of modern range-hoods for Zephyr Ventilation.
By mid-2007 Brunner left Pentagram to start Ammunition Design Group. In 2008, former MetaDesign leaders Brett Wickens and Matt Rolandson joined Ammunition LLC as partners. In 2008, Brunner collaborated with Jimmy Iovine and Dr. Dre to launch Beats by Dre, and is responsible for the design of the company's lines of headphones and speakers including Beats Studio, Powerbeats, Mixr, Solo and Solo Pro as well as the Pill wireless speaker, among others.
Brunner's work has been widely published in North America, Europe, Asia and Australia. His product designs have won 23 IDSA Awards from the Industrial Designers Society of America and Business Week, including 6 best of category awards. His work is included in the permanent collections of the Museum of Modern Art (MoMA), Cooper Hewitt, Smithsonian Design Museum, Indianapolis Museum of Art (IMA), and the San Francisco Museum of Modern Art (SFMoMA).
See |
https://en.wikipedia.org/wiki/Ceroid%20cactus | The term ceroid cactus (or sometimes just cereus) is used to describe any of the species of cacti with very elongated bodies, including columnar growth cacti and epiphytic cacti.
The name is from the Latin cēreus, wax taper (slender candle), referring to the stiff, upright form of the columnar species. Some species of ceroid cacti were known as torch cactus or torch-thistle, supposedly due to their use as torches by Native Americans in the past.
The genus Cereus was first genus for such cacti and one of the oldest cactus genera. Its circumscription varies depending on the authority.
According to Cactiguide the word "cereus" was commonly and freely used to describe any tree-like cacti, although this general use of the word is regarded as misleading and the word ceroid or ceriform is preferred.
Taxonomy
The name cereus originates in a book by Tabernaemontanus published in 1625 and refers to the candle-like form of species Cereus hexagonus. Regularly having been described by Philip Miller in 1754, and included all known cacti with very elongated bodies.
Ludwig Pfeiffer in 1838 divided Cephalocereus (type Cephalocereus senilis), the name is derived from the Greek κεφαλή (kephalē), head, thus headed cereus, referring to the hairy pseudocephalium.
Charles Lemaire described Pilocereus in 1839, now is renamed as Pilosocereus. The name Pilocereus is derived from the Greek pilos, felted, hairy, thus hairy cereus, similar to the Latin pilosus, from which the name Pilosocereus was derived. Genus Echinocereus (type Echinocereus viridiflorus) was described in 1848 by George Engelmann, the name is derived from the Greek echinos, hedgehog or sea urchin. Britton & Rose (1919-1923) and Alwin Berger (1929) continued to divide Cereus into many genera.
In 1984 a new approach to cactus classification was begun. The International Organization for Succulent Plant Study (IOS) founded a working group called the International Cactaceae Systematics Group. The group has recruited specia |
https://en.wikipedia.org/wiki/Normal%20height | Normal heights (symbol or ; SI unit metre, m) is a type of height above sea level introduced by Mikhail Molodenskii.
The normal height of a point is computed as the quotient of a point's geopotential number (i.e. its geopotential difference with that of sea level), by the average, normal gravity computed along the plumb line of the point. (More precisely, along the ellipsoidal normal, averaging over the height range from 0 — on the reference ellipsoid — to ; the procedure is thus recursive.)
Normal heights are thus dependent upon the reference ellipsoid chosen. The Soviet Union and many other Eastern European countries have chosen a height system based on normal heights, determined by precise geodetic levelling. Normal gravity values are easier to compute compared to actual gravity, as one does not have to know the Earth's crust density. This is an advantage of normal heights compared to orthometric heights.
The reference surface that normal heights are measured from is called the quasi-geoid (or quasigeoid), a representation of mean sea level similar to the geoid and close to it, but lacking the physical interpretation of an equipotential surface. The geoid undulation with respect to the reference ellipsoid:
finds an analogue in the so-called height anomaly, :
The maximum geoid–quasigeoid separation (GQS), , is on the order of 5 meters in the Himalayas.
Alternatives to normal heights include orthometric heights (geoid-based) and dynamic heights.
See also
Physical geodesy |
https://en.wikipedia.org/wiki/Hylonomus | Hylonomus (; hylo- "forest" + nomos "dweller") is an extinct genus of reptile that lived 312 million years ago during the Late Carboniferous period.
It is the earliest unquestionable reptile (Westlothiana is older, but in fact it may have been an amphibian, and Casineria is rather fragmentary). The only species is the type species Hylonomus lyelli. Despite being amongst the oldest known reptiles, it is not the most primitive member of group, being a eureptile more derived than either parareptiles or captorhinids.
Description
Hylonomus was long (including the tail). Most of them are 20 cm long and probably would have looked rather similar to modern lizards. It had small sharp teeth and it likely ate small invertebrates such as millipedes or early insects. They are also described to have slender and lightweight leg and arm bones, as well as long and slim hands and feet. A narrow and tongue-shaped part in the roof of the mouth, a deep groove on a certain bone in the skull, a bumpy structure on the back bones, changes in the height of certain back bone parts, having a hole in a specific place on the skull, having arm and leg bones that are the same length, having a short fourth toe bone compared to the shin bone, having a short fifth toe bone compared to the fourth toe bone, having long neck bones, and having a well-developed opening below the eye.
Fossils of Hylonomus have been found in the remains of fossilized club moss stumps in the Joggins Formation, Joggins, Nova Scotia, Canada. It is supposed that, after harsh weather, the club mosses would crash down, with the stumps eventually rotting and hollowing out. Small animals such as Hylonomus, seeking shelter, would enter and become trapped, starving to death. An alternative hypothesis is that the animals made their nests in the hollow tree stumps.
Fossils of the basal pelycosaur Archaeothyris and the basal diapsid Petrolacosaurus are also found in the same region of Nova Scotia, although from a higher stratum, |
https://en.wikipedia.org/wiki/Rvachev%20function | In mathematics, an R-function, or Rvachev function, is a real-valued function whose sign does not change if none of the signs of its arguments change; that is, its sign is determined solely by the signs of its arguments.
Interpreting positive values as true and negative values as false, an R-function is transformed into a "companion" Boolean function (the two functions are called friends). For instance, the R-function ƒ(x, y) = min(x, y) is one possible friend of the logical conjunction (AND). R-functions are used in computer graphics and geometric modeling in the context of implicit surfaces and the function representation. They also appear in certain boundary-value problems, and are also popular in certain artificial intelligence applications, where they are used in pattern recognition.
R-functions were first proposed by () in 1963, though the name, "R-functions", was given later on by Ekaterina L. Rvacheva-Yushchenko, in memory of their father, Logvin Fedorovich Rvachev ().
See also
Function representation
Slesarenko function (S-function)
Notes |
https://en.wikipedia.org/wiki/Halobacterium | Halobacterium (common abbreviation Hbt.) is a genus in the family Halobacteriaceae.
The genus Halobacterium ("salt" or "ocean bacterium") consists of several species of Archaea with an aerobic metabolism which requires an environment with a high concentration of salt; many of their proteins will not function in low-salt environments. They grow on amino acids in their aerobic conditions. Their cell walls are also quite different from those of bacteria, as ordinary lipoprotein membranes fail in high salt concentrations. In shape, they may be either rods or cocci, and in color, either red or purple. They reproduce using binary fission (by constriction), and are motile. Halobacterium grows best in a 42 °C environment. The genome of an unspecified Halobacterium species, sequenced by Shiladitya DasSarma, comprises 2,571,010 bp (base pairs) of DNA compiled into three circular strands: one large chromosome with 2,014,239 bp, and two smaller ones with 191,346 and 365,425 bp. This species, called Halobacterium sp. NRC-1, has been extensively used for postgenomic analysis. Halobacterium species can be found in the Great Salt Lake, the Dead Sea, Lake Magadi, and any other waters with high salt concentration. Purple Halobacterium species owe their color to bacteriorhodopsin, a light-sensitive protein which provides chemical energy for the cell by using sunlight to pump protons out of the cell. The resulting proton gradient across the cell membrane is used to drive the synthesis of the energy carrier ATP. Thus, when these protons flow back in, they are used in the synthesis of ATP (this proton flow can be emulated with a decrease in pH outside the cell, causing a flow of H+ ions). The bacteriorhodopsin protein is chemically very similar to the light-detecting pigment rhodopsin, found in the vertebrate retina.
Species of Halobacterium
Phylogeny
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for |
https://en.wikipedia.org/wiki/Guanacastepene%20A | Guanacastepene A is a compound showing antibiotic activity. It is a diterpene that was extracted with hexane from a Costa Rican fungus, CR115, found on the branches of the Daphnopsis americana tree and purified by chromatography. |
https://en.wikipedia.org/wiki/Wm.%20K.%20Walthers | Wm. K. Walthers, Inc. is a manufacturer and distributor of model railroad supplies and tools.
History
Wm. K. Walthers, Inc., was officially founded in Milwaukee in 1932—though it started years earlier when seven-year-old William K. (Bill) Walthers got his first taste of the hobby with a small, wind-up toy train for Christmas. He continued with the hobby and eventually had an attic layout composed primarily of his scratch-built creations. A series of articles he wrote on building train control and signaling systems led to requests from other modelers that he began manufacturing them. The first ad (in the May issue of The Model Maker) offered a 24-page, 15¢ catalog that listed rail, couplers, and electrical supplies. Sales were over US$500.00 for the first year. By 1935, the catalogs were over 80 pages.
Within five years, Walthers had grown and a larger quarters were needed. Space was found on Erie Street, where everything—from milled wood parts to metal castings to decals—was made in-house.1937 also saw a new line in HO Scale, featured in its catalog. Bill brought operating layouts to the 1939 World's Fair, which gave the hobby a big boost. Soon, though, the growing possibility of war overshadowed these successes.
In 1958, Bill retired, and his son Bruce took over. Just as full-size railroads were being hard-hit by new technology, so too were model railroads. In 1960, Walthers became a full-line distributor of other manufacturers' products while continuing the expansion of the Walthers lines. By the start of the 1970s Bruce's son Phil had joined the company.
Acquisitions, expansions, and vertical integration
Expansion and diversification continue under Phil's tenure. The establishment of the Walthers Importing Division added several international lines. The company made agreements with several European companies to become the exclusive North American distributor for many famous European brands.
The manufacturing plant was modernized. Code 83 track was introduced |
https://en.wikipedia.org/wiki/Geriatric%20dentistry | Geriatric dentistry is the delivery of dental care to older adults involving diagnosis, prevention, management and treatment of problems associated with age related diseases. The mouth is referred to as a mirror of overall health, reinforcing that oral health is an integral part of general health. In the elderly population poor oral health has been considered a risk factor for general health problems. Older adults are more susceptible to oral conditions or diseases due to an increase in chronic conditions and physical/mental disabilities. Thus, the elderly form a distinct group in terms of provision of care.
Ageing Population
The world’s population is currently ageing with the number and proportion of elderly people growing substantially. Between the years of 2000-2005 to 2010-2015 life expectancy at birth rose from 67.2 to 70.8 years. By 2045-2050 it is projected to continue increase to 77 years. This increasing longevity can be majorly attributed to advances in modern medicine and medical technology. As a result, the population of people aged 60 and over is growing faster than any other younger age group and it is expected to more than double by 2050 globally. This will have a profound effect on society’s ability to support the needs of this growing crowd including their dental needs.
Older people have become a major focus for the oral health industry. Due to the increasing number and proportion of elderly people, age related dental problems have become more common. This is largely due to success in dental treatment and prevention of gum disease and caries at a young age, thereby leading to people retaining more of their own natural teeth. As they get older, the retained teeth are at risk of developing and accumulating oral diseases that are more extensive and severe.
Geriatrics as a Dental Specialty
In Australia geriatric dentistry is falls under the ‘Special needs dentistry’ specialty which is recognised by the Dental Board of Australia. This is because oft |
https://en.wikipedia.org/wiki/Relapsing%20polychondritis | Relapsing polychondritis is a multi-systemic condition characterized by repeated episodes of inflammation and deterioration of cartilage. The often painful disease can cause joint deformity and be life-threatening if the respiratory tract, heart valves, or blood vessels are affected. The exact mechanism is poorly understood, but it is thought to be related to an immune-mediated attack on particular proteins that are abundant in cartilage.
The diagnosis is reached on the basis of the symptoms and supported by investigations such as blood tests and sometimes other investigations. Treatment may involve symptomatic treatment with painkillers or anti-inflammatory medications, and more severe cases may require suppression of the immune system.
Signs and symptoms
Though any cartilage in the body may be affected in persons with relapsing polychondritis, in many cases the disease affects several areas while sparing others. The disease may be variable in its signs and symptoms, resulting in a difficult diagnosis which may leads to delayed recognition for several months, years or decades.
Joint symptoms are often one of the first signs of the disease with cartilage inflammation initially absent in nearly half the cases.
Associated diseases
There are several other overlapping diseases associated with RP, that should also be taken into account. About one-third of people with RP might be associated with other autoimmune diseases, vasculitides and hematologic disorders. Systemic vasculitis is the most common association with RP, followed by rheumatoid arthritis and systemic lupus erythematosus.
The following table displays the main diseases in association with RP.
Cartilage inflammation
Cartilage inflammation (technically known as chondritis) that is relapsing is very characteristic of the disease and is required for the diagnosis of RP. These recurrent episodes of inflammation over the course of the disease may result in breakdown and loss of cartilage. The signs and sympto |
https://en.wikipedia.org/wiki/Drag%20count | A drag count is a dimensionless unit used by aerospace engineers. 1 drag count is equal to a of 0.0001.
As the drag forces present on automotive vehicles are smaller than for aircraft, 1 drag count is commonly referred to as 0.001 of .
Definition
A drag count is defined as:
where:
is the drag force, which is by definition the force component in the direction of the flow velocity,
is the mass density of the fluid,
is the speed of the object relative to the fluid, and
is the reference area.
The drag coefficient is used to compare the solutions of different geometries by means of a dimensionless number. A drag count is more user-friendly than the drag coefficient, as the latter is usually much less than 1. A drag count of 200 to 400 is typical for an airplane at cruise. A reduction of one drag count on a subsonic civil transport airplane means about more in payload.
Notes |
https://en.wikipedia.org/wiki/Sieve%20%28mail%20filtering%20language%29 | Sieve is a programming language that can be used for email filtering. It owes its creation to the CMU Cyrus Project, creators of Cyrus IMAP server.
The language is not tied to any particular operating system or mail architecture. It requires the use of RFC-2822–compliant messages, but otherwise generalizes to other systems that meet these criteria. The current version of Sieve's base specification is outlined in RFC 5228, published in January 2008.
Language
Sieve is a data-driven programming language, similar to earlier email filtering languages such as procmail and maildrop, and earlier line-oriented languages such as sed and AWK: it specifies conditions to match and actions to take on matching.
This differs from general-purpose programming languages while this is highly limited – the base standard has no variables, and no loops (but does allow conditional branching), preventing runaway programs which limits the language to simple filtering operations. Although extensions have been devised to extend the language to include variables and, limited loops, the language is still highly restricted, and thus suitable for running user-devised programs as part of the mail system.
There are also a significant number of restrictions on the grammar of the language, in order to reduce the complexity of parsing the language, but the language also supports the use of multiple methods for comparing localized strings, and is fully Unicode-aware.
While Sieve was originally conceived as tool external to SMTP, serendipitously extends it in order to allow rejection at the SMTP protocol level.
Use
The Sieve scripts may be generated by a GUI-based rules editor or they may be entered directly using a text editor.
The scripts are transferred to the mail server in a server-dependent way. The ManageSieve protocol (defined in ) allows users to manage their Sieve scripts on a remote server. Mail servers with local users may allow the scripts to be stored in e.g. a file in the users' h |
https://en.wikipedia.org/wiki/Stenospermocarpy | Stenospermocarpy is the biological mechanism that produces parthenocarpy (seedlessness) in some fruits, notably many table grapes.
In stenospermocarpic fruits, normal pollination and fertilization are still required to ensure that the fruit 'sets', i.e. continues to develop on the plant; however subsequent abortion of the embryo that began growing following fertilization leads to a near seedless condition. The remains of the undeveloped seed are visible in the fruit.
Most commercial seedless grapes are sprayed with gibberellin to increase the size of the fruit and also to make the fruit clusters less tightly packed. A new cultivar, 'Melissa', has naturally larger fruit so does not require gibberellin sprays.
Grape breeders have developed some new seedless grape cultivars by using the embryo rescue technique. Before the tiny embryo aborts, it is removed from the developing fruit and grown in tissue culture until it is large enough to survive on its own. Embryo rescue allows the crossing of two seedless grape cultivars.
There are two types of seedlessness in grapes: true seedlessness of parthenocarpic berries when only ovules may develop and commercial seedlessness of stenospermocarpic berries when aborted seeds go unnoticed when chewing. Stenospermocarpic seeds vary significant in size and in the degree of development of the seed coat and the endosperm. Larger seeds of stenospermocarpic grapes are referred to as rudimentary seeds and smaller ones as seed traces. A scientific article with many photos of ovules, aborted and normal seeds of the parthenocarpic, stenospermocarpic and seeded cultivars.
Seedless grape cultivars
Seedless grapes are divided into white, red and black types based roughly on fruit color. The most popular seedless grape is known in the United States as 'Thompson Seedless', but was originally known as 'Sultana'. It is believed to be of ancient origin. It is considered a white grape, but is actually a pale green. Other white cultivars are 'Pe |
https://en.wikipedia.org/wiki/Conrad%20Elvehjem | Conrad Arnold Elvehjem (May 27, 1901July 27, 1962) was internationally known as an American biochemist in nutrition. In 1937 he identified two vitamins, nicotinic acid, also known as niacin, and nicotinamide, which were deficient directly in human pellagra, once a major health problem in the United States. Collectively, nicotinic acid and nicotinamide are termed vitamin B3 and are now understood to be precursors of nicotinamide adenine dinucleotide.
Biography
Conrad Elvehjem, the son of Norwegian emigrants to Wisconsin, was born in McFarland, Wisconsin. He progressed through the secondary schools and the University of Wisconsin, where he received his PhD in 1927 with mentor E. B. Hart for his studies of the importance of copper in iron-deficiency anemia. A National Research Council fellowship permitted a year at Cambridge University in England. Elvehjem began teaching in agricultural chemistry at the University of Wisconsin in 1923, and became a full professor in 1936. He became chairman of the biochemistry department in 1944 and dean of the graduate school in 1946, at 45 years of age. He served as dean of the graduate school until he became the university's 13th president in 1958.
Picking up on the work of Joseph Goldberger, he found that nicotinic acid cured black tongue in dogs, an analogous disease to pellagra. In the previous year, Elvehjem and his colleague Carl J. Koehn had found that a filtrate factor from a liver extract could cure diet-induced pellagra in chicks. That filtrate extract was designated as the vitamin G fraction, after the late Goldberger. To confirm their findings in dogs, they induced black tongue in these animals with the Goldberger diet of yellow corn, before supplementing the diet with the vitamin G fraction. Elvehjem and his colleagues later were able to isolate and identify nicotinamide and nicotinic acid from vitamin G as the curative factors for black tongue in dogs. He also contributed greatly to the identification of vitamin B |
https://en.wikipedia.org/wiki/Level-spacing%20distribution | In mathematical physics, level spacing is the difference between consecutive elements in some set of real numbers. In particular, it is the difference between consecutive energy levels or eigenvalues of a matrix or linear operator.
Mathematical physics |
https://en.wikipedia.org/wiki/Fredholm%20determinant | In mathematics, the Fredholm determinant is a complex-valued function which generalizes the determinant of a finite dimensional linear operator. It is defined for bounded operators on a Hilbert space which differ from the identity operator by a trace-class operator. The function is named after the mathematician Erik Ivar Fredholm.
Fredholm determinants have had many applications in mathematical physics, the most celebrated example being Gábor Szegő's limit formula, proved in response to a question raised by Lars Onsager and C. N. Yang on the spontaneous magnetization of the Ising model.
Definition
Let be a Hilbert space and the set of bounded invertible operators on of the form
, where is a trace-class operator. is a group because
so is trace class if is. It has a natural metric given by
, where is the trace-class norm.
If is a Hilbert space with inner product , then so too is the th exterior power
with inner product
In particular
gives an orthonormal basis of if is an orthonormal basis of .
If is a bounded operator on , then functorially defines a bounded operator on by
If is trace-class, then is also trace-class with
This shows that the definition of the Fredholm determinant given by
makes sense.
Properties
If is a trace-class operator
defines an entire function such that
The function is continuous on trace-class operators, with
One can improve this inequality slightly to the following, as noted in Chapter 5 of Simon:
If and are trace-class then
The function defines a homomorphism of into the multiplicative group of nonzero complex numbers (since elements of are invertible).
If is in and is invertible,
If is trace-class, then
Fredholm determinants of commutators
A function from into is said to be differentiable if is differentiable as a map into the trace-class operators, i.e. if the limit
exists in trace-class norm.
If is a differentiable function with values in trace-class operators, then so |
https://en.wikipedia.org/wiki/Psychometric%20function | A psychometric function is an inferential psychometric model applied in detection and discrimination tasks. It models the relationship between a given feature of a physical stimulus, e.g. velocity, duration, brightness, weight etc., and forced-choice responses of a human or animal test subject. The psychometric function therefore is a specific application of the generalized linear model (GLM) to psychophysical data. The probability of response is related to a linear combination of predictors by means of a sigmoid link function (e.g. probit, logit, etc.).
Design
Depending on the number of choices, the psychophysical experimental paradigms classify as simple forced choice (also known as yes-no task), two-alternative forced choice (2AFC), and n-alternative forced choice. The number of alternatives in the experiment determine the lower asymptote of the function.
Example
A common example is visual acuity testing with an eye chart. The person sees symbols of different sizes (the size is the relevant physical stimulus parameter) and has to decide which symbol it is. Usually, there is one line on the chart where a subject can identify some, but not all, symbols. This is equal to the transition range of the psychometric function and the sensory threshold corresponds to visual acuity. (Strictly speaking, a typical optometric measurement does not exactly yield the sensory threshold due to biases in the standard procedure.)
Plotting
Two different types of psychometric plots are in common use:
Plot the percentage of correct responses (or a similar value) displayed on the y-axis and the physical parameter on the x-axis. If the stimulus parameter is very far towards one end of its possible range, the person will always be able to respond correctly. Towards the other end of the range, the person never perceives the stimulus properly and therefore the probability of correct responses is at chance level. In between, there is a transition range where the subject has an above-c |
https://en.wikipedia.org/wiki/Z-Wave | Z-Wave is a wireless communications protocol used primarily for residential and commercial building automation. It is a mesh network using low-energy radio waves to communicate from device to device, allowing for wireless control of smart home devices, such as smart lights, security systems, thermostats, sensors, smart door locks, and garage door openers. The Z-Wave brand and technology are owned by Silicon Labs. Over 300 companies involved in this technology are gathered within the Z-Wave Alliance.
Like other protocols and systems aimed at the residential, commercial, MDU and building markets, a Z-Wave system can be controlled from a smart phone, tablet, or computer, and locally through a smart speaker, wireless keyfob, or wall-mounted panel with a Z-Wave gateway or central control device serving as both the hub or controller. Z-Wave provides the application layer interoperability between home control systems of different manufacturers that are a part of its alliance. There is a growing number of interoperable Z-Wave products; over 1,700 in 2017, over 2,600 by 2019, and over 4,000 by 2022.
History
The Z-Wave protocol was developed by Zensys, a Danish company based in Copenhagen, in 1999. That year, Zensys introduced a consumer light-control system, which evolved into Z-Wave as a proprietary system on a chip (SoC) home automation protocol on an unlicensed frequency band in the 900 MHz range. Its 100 series chip set was released in 2003, and its 200 series was released in May 2005, with the ZW0201 chip offering high performance at a low cost. Its 500 series chip, also known as Z-Wave Plus, was released in March 2013, with four times the memory, improved wireless range, improved battery life, an enhanced S2 security framework, and the SmartStart setup feature. Its 700 series chip was released in 2019, with the ability to communicate up to 100 meters directly from point-to-point, or 800 meters across an entire Z-Wave network, an extended battery life of up to 10 year |
https://en.wikipedia.org/wiki/Attosecond%20physics | Attosecond physics, also known as attophysics, or more generally attosecond science, is a branch of physics that deals with light-matter interaction phenomena wherein attosecond (10−18 s) photon pulses are used to unravel dynamical processes in matter with unprecedented time resolution.
Attosecond science mainly employs pump–probe spectroscopic methods to investigate the physical process of interest. Due to the complexity of this field of study, it generally requires a synergistic interplay between state-of-the-art experimental setup and advanced theoretical tools to interpret the data collected from attosecond experiments.
The main interests of attosecond physics are:
Atomic physics: investigation of electron correlation effects, photo-emission delay and ionization tunneling.
Molecular physics and molecular chemistry: role of electronic motion in molecular excited states (e.g. charge-transfer processes), light-induced photo-fragmentation, and light-induced electron transfer processes.
Solid-state physics: investigation of exciton dynamics in advanced 2D materials, petahertz charge carrier motion in solids, spin dynamics in ferromagnetic materials.
One of the primary goals of attosecond science is to provide advanced insights into the quantum dynamics of electrons in atoms, molecules and solids with the long-term challenge of achieving real-time control of the electron motion in matter.
The advent of broadband solid-state titanium-doped sapphire based (Ti:Sa) lasers (1986), chirped pulse amplification (CPA) (1988), spectral broadening of high-energy pulses (e.g. gas-filled hollow-core fiber via self-phase modulation) (1996), mirror-dispersion-controlled technology (chirped mirrors) (1994), and carrier envelop offset stabilization (2000) had enabled the creation of isolated-attosecond light pulses (generated by the non-linear process of high harmonic generation in a noble gas) (2004, 2006), which have given birth to the field of attosecond science.
The curren |
https://en.wikipedia.org/wiki/Physical%20symbol%20system | A physical symbol system (also called a formal system) takes physical patterns (symbols), combining them into structures (expressions) and manipulating them (using processes) to produce new expressions.
The physical symbol system hypothesis (PSSH) is a position in the philosophy of artificial intelligence formulated by Allen Newell and Herbert A. Simon. They wrote:
This claim implies both that human thinking is a kind of symbol manipulation (because a symbol system is necessary for intelligence) and that machines can be intelligent (because a symbol system is sufficient for intelligence).
The idea has philosophical roots in Hobbes (who claimed reasoning was "nothing more than reckoning"), Leibniz (who attempted to create a logical calculus of all human ideas), Hume (who thought perception could be reduced to "atomic impressions") and even Kant (who analyzed all experience as controlled by formal rules). The latest version is called the computational theory of mind, associated with philosophers Hilary Putnam and Jerry Fodor.
Examples
Examples of physical symbol systems include:
Formal logic: the symbols are words like "and", "or", "not", "for all x" and so on. The expressions are statements in formal logic which can be true or false. The processes are the rules of logical deduction.
Algebra: the symbols are "+", "×", "x", "y", "1", "2", "3", etc. The expressions are equations. The processes are the rules of algebra, that allow one to manipulate a mathematical expression and retain its truth.
Chess: the symbols are the pieces, the processes are the legal chess moves, the expressions are the positions of all the pieces on the board.
A computer running a program: the symbols and expressions are data structures, the process is the program that changes the data structures.
The physical symbol system hypothesis claims that both of these are also examples of physical symbol systems:
Intelligent human thought: the symbols are encoded in our brains. The expressi |
https://en.wikipedia.org/wiki/Piezophile | A piezophile (from Greek "piezo-" for pressure and "-phile" for loving) is an organism with optimal growth under high hydrostatic pressure i.e. an organism that has its maximum rate of growth at a hydrostatic pressure equal to or above 10 MPa (= 99 atm = 1,450 psi), when tested over all permissible temperatures. Originally, the term barophile was used for these organisms, but since the prefix "baro-" stands for weight, the term piezophile was given preference. Like all definitions of extremophiles, the definition of piezophiles is anthropocentric, and humans consider that moderate values for hydrostatic pressure are those around 1 atm (= 0.1 MPa = 14.7 psi), whereas those "extreme" pressures are the normal living conditions for those organisms. Hyperpiezophiles are organisms that have their maximum growth rate above 50 MPa (= 493 atm = 7,252 psi).
Though the high hydrostatic pressure has deleterious effects on organisms growing at atmospheric pressure, these organisms which are solely found at high pressure habitats at deep sea in fact need high pressures for their optimum growth. Often their growth is able to continue at much higher pressures (such as 100MPa) compared to those organisms which normally grow at low pressures.
The first obligate piezophile found was a psychrophilic bacteria called Colwellia marinimaniae strain M-41. It was isolated from a decaying amphipod Hirondellea gigas from the bottom of Mariana Trench. The first thermophilic piezophilic archaea Pyrococcus yayanosii strain CH1 was isolated from the Ashadze site, a deep sea hydrothermal vent. Strain MT-41 has an optimal growth pressure at 70MPa at 2 °C and strain CH1 has a optimal growth pressure at 52MPa at 98 °C. They are unable to grow at pressures lower than or equal to 20MPa, and both can grow at pressures above 100MPa.The current record for highest hydrostatic pressure where growth was observed is 140MPa shown by Colwellia marinimaniae MTCD1. The term "obligate piezophile" refers to organ |
https://en.wikipedia.org/wiki/Aerospace%20physiology | Aerospace physiology is the study of the effects of high altitudes on the body, such as different pressures and levels of oxygen. At different altitudes the body may react in different ways, provoking more cardiac output, and producing more erythrocytes. These changes cause more energy waste in the body, causing muscle fatigue, but this varies depending on the level of the altitude.
Effects of altitude
The physics that affect the body in the sky or in space are different from the ground. For example, barometric pressure is different at different heights. At sea level barometric pressure is 760 mmHg; at 3.048 m above sea level, barometric pressure is 523 mmHg, and at 15.240 m, the barometric pressure is 87 mmHg. As the barometric pressure decreases, atmospheric partial pressure decreases also. This pressure is always below 20% of the total barometric pressure. At sea level, alveolar partial pressure of oxygen is 104 mmHg, reaching 6000 meters above the sea level. This pressure will decrease up to 40 mmHg in a non-acclimated person, but in an acclimated person, it will decrease as much as 52 mmHg. This is because alveolar ventilation will increase more in the acclimated person. Aviation physiology can also include the effect in humans and animals exposed for long periods of time inside pressurized cabins.
The other main issue with altitude is hypoxia, caused by both the lack of barometric pressure and the decrease in oxygen as the body rises. With exposure at higher altitudes, alveolar carbon dioxide partial pressure (PCO2) decreases from 40 mmHg (sea level) to lower levels. With a person acclimated to sea level, ventilation increases about five times and the carbon dioxide partial pressure decreases up to 6 mmHg. In an altitude of 3040 meters, arterial saturation of oxygen elevates to 90%, but over this altitude arterial saturation of oxygen decreases rapidly as much as 70% (6000 m), and decreases more at higher altitudes.
g-forces
g-forces are mostly experience |
https://en.wikipedia.org/wiki/Tryptone | Tryptone is the assortment of peptides formed by the digestion of casein by the protease trypsin.
Tryptone is commonly used in microbiology to produce lysogeny broth (LB) for the growth of E. coli and other microorganisms. It provides a source of amino acids for the growing bacteria. Tryptone is similar to casamino acids, both being digests of casein, but casamino acids can be produced by acid hydrolysis and typically only have free amino acids and few peptide chains; tryptone by contrast is the product of an incomplete enzymatic hydrolysis with some oligopeptides present.
Tryptone is also a component of some germination media used in plant propagation.
See also
Albumose
Trypticase soy agar |
https://en.wikipedia.org/wiki/Ring%20of%20sets | In mathematics, there are two different notions of a ring of sets, both referring to certain families of sets.
In order theory, a nonempty family of sets is called a ring (of sets) if it is closed under union and intersection. That is, the following two statements are true for all sets and ,
implies and
implies
In measure theory, a nonempty family of sets is called a ring (of sets) if it is closed under union and relative complement (set-theoretic difference). That is, the following two statements are true for all sets and ,
implies and
implies
This implies that a ring in the measure-theoretic sense always contains the empty set. Furthermore, for all sets and ,
which shows that a family of sets closed under relative complement is also closed under intersection, so that a ring in the measure-theoretic sense is also a ring in the order-theoretic sense.
Examples
If is any set, then the power set of (the family of all subsets of ) forms a ring of sets in either sense.
If is a partially ordered set, then its upper sets (the subsets of with the additional property that if belongs to an upper set U and , then must also belong to ) are closed under both intersections and unions. However, in general it will not be closed under differences of sets.
The open sets and closed sets of any topological space are closed under both unions and intersections.
On the real line , the family of sets consisting of the empty set and all finite unions of half-open intervals of the form , with is a ring in the measure-theoretic sense.
If is any transformation defined on a space, then the sets that are mapped into themselves by are closed under both unions and intersections.
If two rings of sets are both defined on the same elements, then the sets that belong to both rings themselves form a ring of sets.
Related structures
A ring of sets in the order-theoretic sense forms a distributive lattice in which the intersection and union operations correspond to the |
https://en.wikipedia.org/wiki/A%20Hole%20in%20Texas | A Hole In Texas is a novel by Herman Wouk. Published in 2004, the book describes the adventures of a high-energy physicist following the surprise announcement that a Chinese physicist (with whom he had a long-ago romance) had discovered the long-sought Higgs boson.
Parts of the plot are based on the aborted Superconducting Super Collider project.
Published by Little, Brown and Company, .
Literary significance and reception
Kirkus Reviews said that A Hole In Texas was "Ingenious. Absolutely ingenious." Publishers Weekly called it "Occasionally corny but also playful, thoughtful and passionate". The journal Science said that Wouk "accurately depicts science as an often interactive and collegial enterprise", and that the novel offers a "refreshing contrast with the treatments of mad scientists that are so abundant in literature and popular culture." The review in Nature had some criticism, saying that the "scientific explanations are pat and usually come in the form of long e-mails that bog down the plot", that the discussions of the Chinese people "verge on racism", and that the book's ending "falls flat".
Notes
2004 American novels
Novels about NASA
Novels by Herman Wouk
Novels set in Texas
Works about particle physics |
https://en.wikipedia.org/wiki/Polyphenism | A polyphenic trait is a trait for which multiple, discrete phenotypes can arise from a single genotype as a result of differing environmental conditions. It is therefore a special case of phenotypic plasticity.
There are several types of polyphenism in animals, from having sex determined by the environment to the castes of honey bees and other social insects. Some polyphenisms are seasonal, as in some butterflies which have different patterns during the year, and some Arctic animals like the snowshoe hare and Arctic fox, which are white in winter. Other animals have predator-induced or resource polyphenisms, allowing them to exploit variations in their environment. Some nematode worms can develop either into adults or into resting dauer larvae according to resource availability.
Definition
A polyphenism is the occurrence of several phenotypes in a population, the differences between which are not the result of genetic differences. For example, crocodiles possess a temperature-dependent sex determining polyphenism, where sex is the trait influenced by variations in nest temperature.
When polyphenic forms exist at the same time in the same panmictic (interbreeding) population they can be compared to genetic polymorphism. With polyphenism, the switch between morphs is environmental, but with genetic polymorphism the determination of morph is genetic. These two cases have in common that more than one morph is part of the population at any one time. This is rather different from cases where one morph predictably follows another during, for instance, the course of a year. In essence the latter is normal ontogeny where young forms can and do have different forms, colours and habits to adults.
The discrete nature of polyphenic traits differentiates them from traits like weight and height, which are also dependent on environmental conditions but vary continuously across a spectrum. When a polyphenism is present, an environmental cue causes the organism to develop along |
https://en.wikipedia.org/wiki/Microsoft%20Analysis%20Services | Microsoft SQL Server Analysis Services (SSAS) is an online analytical processing (OLAP) and data mining tool in Microsoft SQL Server. SSAS is used as a tool by organizations to analyze and make sense of information possibly spread out across multiple databases, or in disparate tables or files. Microsoft has included a number of services in SQL Server related to business intelligence and data warehousing. These services include Integration Services, Reporting Services and Analysis Services. Analysis Services includes a group of OLAP and data mining capabilities and comes in two flavors multidimensional and tabular, where the difference between the two is how the data is presented. In a tabular model, the information is arranged in two-dimensional tables which can thus be more readable for a human. A multidimensional model can contain information with many degrees of freedom, and must be unfolded to increase readability by a human.
History
In 1996, Microsoft began its foray into the OLAP Server business by acquiring the OLAP software technology from Canada-based Panorama Software.
Just over two years later, in 1998, Microsoft released OLAP Services as part of SQL Server 7. OLAP Services supported MOLAP, ROLAP, and HOLAP architectures, and it used OLE DB for OLAP as the client access API and MDX as a query language. It could work in client-server mode or offline mode with local cube files.
In 2000, Microsoft released Analysis Services 2000. It was renamed from "OLAP Services" due to the inclusion of data mining services. Analysis Services 2000 was considered an evolutionary release, since it was built on the same architecture as OLAP Services and was therefore backward compatible with it. Major improvements included more flexibility in dimension design through support of parent child dimensions, changing dimensions, and virtual dimensions. Another feature was a greatly enhanced calculation engine with support for unary operators, custom rollups, and cell calculation |
https://en.wikipedia.org/wiki/Interferon%20gamma | Interferon gamma (IFN-γ) is a dimerized soluble cytokine that is the only member of the type II class of interferons. The existence of this interferon, which early in its history was known as immune interferon, was described by E. F. Wheelock as a product of human leukocytes stimulated with phytohemagglutinin, and by others as a product of antigen-stimulated lymphocytes. It was also shown to be produced in human lymphocytes. or tuberculin-sensitized mouse peritoneal lymphocytes challenged with Mantoux test (PPD); the resulting supernatants were shown to inhibit growth of vesicular stomatitis virus. Those reports also contained the basic observation underlying the now widely employed IFN-γ release assay used to test for tuberculosis. In humans, the IFN-γ protein is encoded by the IFNG gene.
Through cell signaling, IFN-γ plays a role in regulating the immune response of its target cell. A key signaling pathway that is activated by type II IFN is the JAK-STAT signaling pathway. IFN-γ plays an important role in both innate and adaptive immunity. Type II IFN is primarily secreted by adaptive immune cells, more specifically CD4+ T helper 1 (Th1) cells, natural killer (NK) cells, and CD8+ cytotoxic T cells. The expression of type II IFN is upregulated and downregulated by cytokines. By activating signaling pathways in cells such as macrophages, B cells, and CD8+ cytotoxic T cells, it is able to promote inflammation, antiviral or antibacterial activity, and cell proliferation and differentiation. Type II IFN is serologically different from interferon type 1, binds to different receptors, and is encoded by a separate chromosomal locus. Type II IFN has played a role in the development of cancer immunotherapy treatments due to its ability to prevent tumor growth.
Function
IFN-γ, or type II interferon, is a cytokine that is critical for innate and adaptive immunity against viral, some bacterial and protozoan infections. IFN-γ is an important activator of macrophages and in |
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