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https://en.wikipedia.org/wiki/Libipq
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libipq is a development library for iptables userspace packet queuing. Libipq provides an API for communicating with ip_queue.
Libipq has been deprecated in favour of the newer libnetfilter_queue in Linux kernel-2.6.14 onwards.
Use in widely used software applications
libipq has been used by some widely deployed applications as their interface to the Linux kernel-space iptables packet filter.
Snort - Snort is an Intrusion Detection System which runs in user-space and uses libipq to interface with Linux's iptables packet filter.
External links
iptables at netfilter.org
libipq subversion repository
Linux Man Page
A quick intro to libipq
Libipq network simulator example
Linux kernel features
Linux security software
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https://en.wikipedia.org/wiki/Disclosure%20and%20Barring%20Service
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The Disclosure and Barring Service (DBS) is a non-departmental public body of the Home Office of the United Kingdom. The DBS enables organisations in the public, private and voluntary sectors to make safer recruitment decisions by identifying candidates who may be unsuitable for certain work, especially involving children or vulnerable adults, and provides wider access to criminal record information through its disclosure service for England and Wales.
Legal context
It is a legal requirement in the UK for regulated activity employers to notify the DBS if a person leaves or changes their job in relation to having harmed someone. It is an offence for any person who has been barred by the DBS to work or apply to work in Regulated Activity (whether paid or voluntary) with the group (children or adults) from which they are barred. It is also an offence for an employer to knowingly employ a barred person in regulated activity with the group from which they are barred.
An organisation which is entitled to ask exempted questions (under the Rehabilitation of Offenders Act 1974) must register with the DBS, or a registered DBS Umbrella Body before they can request a DBS check on an applicant. The applicant applies to the DBS with their application countersigned by the DBS Registered Organisation or Umbrella Body. The applicant's criminal record is then accessed from the Police National Computer (PNC), as well as checked, if appropriate, against lists of people considered unsuitable to work with children and vulnerable people maintained by the DBS (formerly maintained by the Independent Safeguarding Authority. A copy of the completed certificate is sent to the applicant's home address.
If an individual or organisation has safeguarding concerns regarding a member of staff, they can make a safeguarding referral to the DBS who will work with multiple agencies to assess whether that individual should be Barred from working in regulated activity with children and/or vulnerable gr
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https://en.wikipedia.org/wiki/Open%20Media%20Network
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The Open Media Network (OMN) was a P2PTV service and application which provided distribution of educational and public service programs. The network was founded in 2005 by Netscape pioneers Mike Homer and Marc Andreessen. After operating for an extended beta period, development ended with the serious illness and subsequent death in 2009 of founder Homer.
The OMN network operated as a large, centrally controlled grid network for the distribution of free radio and TV content over P2P, described as "part TiVo, part BitTorrent file swapping". The Open Media Network client application was available for Apple Mac OS X (but not Intel based Macs as of October 2007) and Microsoft Windows (XP and 2000, but not Vista as of October 2007).
The OMN infrastructure was powered by Kontiki grid network technology, a commercial alternative to BitTorrent.
The U.S. Public Broadcasting Service (PBS) launched a "download to own" initiative with OMN and Google which allowed viewers to purchase episodes of popular PBS programs via the Internet for viewing anytime, anywhere. The fees for downloading videos ranged from about $2 to about $8 (U.S.). Video files were made available in whatever format the producer chose, including WMV, QuickTime and Google's GVI format.
See also
PPLive
Cybersky-TV
Octoshape
Miro
References
File sharing networks
BitTorrent clients
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https://en.wikipedia.org/wiki/P2PTV
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P2PTV refers to peer-to-peer (P2P) software applications designed to redistribute video streams in real time on a P2P network; the distributed video streams are typically TV channels from all over the world but may also come from other sources. The draw to these applications is significant because they have the potential to make any TV channel globally available by any individual feeding the stream into the network where each peer joining to watch the video is a relay to other peer viewers, allowing a scalable distribution among a large audience with no incremental cost for the source.
Technology and use
In a P2PTV system, each user, while downloading a video stream, is simultaneously also uploading that stream to other users, thus contributing to the overall available bandwidth. The arriving streams are typically a few minutes time-delayed compared to the original sources. The video quality of the channels usually depends on how many users are watching; the video quality is better if there are more users.
The architecture of many P2PTV networks can be thought of as real-time versions of BitTorrent: if a user wishes to view a certain channel, the P2PTV software contacts a "tracker server" for that channel in order to obtain addresses of peers who distribute that channel; it then contacts these peers to receive the feed. The tracker records the user's address, so that it can be given to other users who wish to view the same channel. In effect, this creates an overlay network on top of the regular internet for the distribution of real-time video content.
The need for a tracker can also be eliminated by the use of distributed hash table technology.
Some applications allow users to broadcast their own streams, whether self-produced, obtained from a video file, or through a TV tuner card or video capture card. Many of the commercial P2PTV applications were developed in China (TVUPlayer, PPLive, QQLive, PPStream). The majority of available applications broadcast mainly
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https://en.wikipedia.org/wiki/Guess%20value
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In mathematical modeling, a guess value is more commonly called a starting value or initial value. These are necessary for most optimization problems which use search algorithms, because those algorithms are mainly deterministic and iterative, and they need to start somewhere. One common type of application is nonlinear regression.
Use
The quality of the initial values can have a considerable impact on the success or lack of such of the search algorithm. This is because the fitness function or objective function (in many cases a sum of squared errors (SSE)) can have difficult shapes. In some parts of the search region, the function may increase exponentially, in others quadratically, and there may be regions where the function asymptotes to a plateau. Starting values that fall in an exponential region can lead to algorithm failure because of arithmetic overflow. Starting values that fall in the asymptotic plateau region can lead to algorithm failure because of "dithering". Deterministic search algorithms may use a slope function to go to a minimum. If the slope is very small, then underflow errors can cause the algorithm to wander, seemingly aimlessly; this is dithering.
Finding value
Guess values can be determined a number of ways. Guessing is one of them. If one is familiar with the type of problem, then this is an educated guess or guesstimate. Other techniques include linearization, solving simultaneous equations, reducing dimensions, treating the problem as a time series, converting the problem to a (hopefully) linear differential equation, and using mean values. Further methods for determining starting values and optimal values in their own right come from stochastic methods, the most commonly known of these being evolutionary algorithms and particularly genetic algorithms.
Mathematical optimization
Regression analysis
Computational statistics
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https://en.wikipedia.org/wiki/Bitonic%20sorter
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Bitonic mergesort is a parallel algorithm for sorting. It is also used as a construction method for building a sorting network. The algorithm was devised by Ken Batcher. The resulting sorting networks consist of comparators and have a delay of , where is the number of items to be sorted. This makes it a popular choice for sorting large numbers of elements on an architecture which itself contains a large number of parallel execution units running in lockstep, such as a typical GPU.
A sorted sequence is a monotonically non-decreasing (or non-increasing) sequence. A bitonic sequence is a sequence with for some , or a circular shift of such a sequence.
Complexity
Let and .
It is evident from the construction algorithm that the number of rounds of parallel comparisons is given by .
It follows that the number of comparators is bounded (which establishes an exact value for when is a power of 2).
Although the absolute number of comparisons is typically higher than Batcher's odd-even sort, many of the consecutive operations in a bitonic sort retain a locality of reference, making implementations more cache-friendly and typically more efficient in practice.
How the algorithm works
The following is a bitonic sorting network with 16 inputs:
The 16 numbers enter as the inputs at the left end, slide along each of the 16 horizontal wires, and exit at the outputs at the right end. The network is designed to sort the elements, with the largest number at the bottom.
The arrows are comparators. Whenever two numbers reach the two ends of an arrow, they are compared to ensure that the arrow points toward the larger number. If they are out of order, they are swapped. The colored boxes are just for illustration and have no effect on the algorithm.
Every red box has the same structure: each input in the top half is compared to the corresponding input in the bottom half, with all arrows pointing down (dark red) or all up (light red). If the inputs happen to form a biton
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https://en.wikipedia.org/wiki/UNOS%20%28operating%20system%29
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UNOS is the first, now discontinued, 32-bit Unix-like real-time operating system (RTOS) with real-time extensions. It was developed by Jeffery Goldberg, MS. who left Bell Labs after using Unix and became VP of engineering for Charles River Data Systems (CRDS), now defunct. UNOS was written to capitalize on the first 32-bit microprocessor, the Motorola 68k central processing unit (CPU). CRDS sold a UNOS based 68K system, and sold porting services and licenses to other manufacturers who had embedded CPUs.
History
Jeff Goldberg created an experimental OS using only eventcounts for synchronization, that allowed a preemptive kernel, for a Charles River Data Systems (CRDS) PDP-11. CRDS hired Goldberg to create UNOS and began selling it in 1981.
UNOS was written for the Motorola 68000 series processors. While compatible with Version 7 Unix, it is also an RTOS. CRDS supported it on the company's Universe 68 computers, as did Motorola's Versabus systems. CRDS's primary market was OEMs embedding the CRDS unit within a larger pile of hardware, often requiring better real-time response than Unix could deliver.
UNOS has a cleaner kernel interface than UNIX in 1981. There was e.g., a system call to obtain ps information instead of reading /dev/kmem.
UNOS required memory protection, with the 68000 using an MMU developed by CRDS; and only used Motorola MMUs after UNOS 7 on the 68020 (CRDS System CP20) (using the MC68851 PMMU).
UNOS was written in the programming languages C and assembly language, and supported Fortran, COBOL, Pascal, and Business Basic.
Limits
UNOS from CRDS never supported paged virtual memory and multiprocessor support had not been built in from the start, so the kernel remained mostly single-threaded on the few multiprocessor systems built.
A UNOS variant enhanced by H. Berthold AG under the name vBertOS added demanded page loading and paged processes in 1984, but was given up in favor of SunOS because of the missing GUI and the missing networking code in
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https://en.wikipedia.org/wiki/Symmetry%20in%20mathematics
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Symmetry occurs not only in geometry, but also in other branches of mathematics. Symmetry is a type of invariance: the property that a mathematical object remains unchanged under a set of operations or transformations.
Given a structured object X of any sort, a symmetry is a mapping of the object onto itself which preserves the structure. This can occur in many ways; for example, if X is a set with no additional structure, a symmetry is a bijective map from the set to itself, giving rise to permutation groups. If the object X is a set of points in the plane with its metric structure or any other metric space, a symmetry is a bijection of the set to itself which preserves the distance between each pair of points (i.e., an isometry).
In general, every kind of structure in mathematics will have its own kind of symmetry, many of which are listed in the given points mentioned above.
Symmetry in geometry
The types of symmetry considered in basic geometry include reflectional symmetry, rotation symmetry, translational symmetry and glide reflection symmetry, which are described more fully in the main article Symmetry (geometry).
Symmetry in calculus
Even and odd functions
Even functions
Let f(x) be a real-valued function of a real variable, then f is even if the following equation holds for all x and -x in the domain of f:
Geometrically speaking, the graph face of an even function is symmetric with respect to the y-axis, meaning that its graph remains unchanged after reflection about the y-axis. Examples of even functions include , x2, x4, cos(x), and cosh(x).
Odd functions
Again, let f be a real-valued function of a real variable, then f is odd if the following equation holds for all x and -x in the domain of f:
That is,
Geometrically, the graph of an odd function has rotational symmetry with respect to the origin, meaning that its graph remains unchanged after rotation of 180 degrees about the origin. Examples of odd functions are x, x3, sin(x), sinh(x), and
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https://en.wikipedia.org/wiki/3D%20scanning
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3D scanning is the process of analyzing a real-world object or environment to collect three dimensional data of its shape and possibly its appearance (e.g. color). The collected data can then be used to construct digital 3D models.
A 3D scanner can be based on many different technologies, each with its own limitations, advantages and costs. Many limitations in the kind of objects that can be digitised are still present. For example, optical technology may encounter many difficulties with dark, shiny, reflective or transparent objects. For example, industrial computed tomography scanning, structured-light 3D scanners, LiDAR and Time Of Flight 3D Scanners can be used to construct digital 3D models, without destructive testing.
Collected 3D data is useful for a wide variety of applications. These devices are used extensively by the entertainment industry in the production of movies and video games, including virtual reality. Other common applications of this technology include augmented reality, motion capture, gesture recognition, robotic mapping, industrial design, orthotics and prosthetics, reverse engineering and prototyping, quality control/inspection and the digitization of cultural artifacts.
Functionality
The purpose of a 3D scanner is usually to create a 3D model. This 3D model consists of a polygon mesh or point cloud of geometric samples on the surface of the subject. These points can then be used to extrapolate the shape of the subject (a process called reconstruction). If colour information is collected at each point, then the colours or textures on the surface of the subject can also be determined.
3D scanners share several traits with cameras. Like most cameras, they have a cone-like field of view, and like cameras, they can only collect information about surfaces that are not obscured. While a camera collects colour information about surfaces within its field of view, a 3D scanner collects distance information about surfaces within its field of vie
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https://en.wikipedia.org/wiki/Local%20Inter-Process%20Communication
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The Local Inter-Process Communication (LPC, often also referred to as Local Procedure Call or Lightweight Procedure Call) is an internal, undocumented inter-process communication facility provided by the Microsoft Windows NT kernel for lightweight IPC between processes on the same computer. As of Windows Vista, LPC has been rewritten as Asynchronous Local Inter-Process Communication (ALPC, often also Advanced Local Procedure Call) in order to provide a high-speed scalable communication mechanism required to efficiently implement User-Mode Driver Framework (UMDF), whose user-mode parts require an efficient communication channel with UMDF's components in the executive.
The (A)LPC interface is part of Windows NT's undocumented Native API, and as such is not available to applications for direct use. However, it can be used indirectly in the following instances:
when using the Microsoft RPC API to communicate locally, i.e. between the processes on the same machine
by calling Windows APIs that are implemented with (A)LPC (see below)
Implementation
(A)LPC is implemented using kernel "port" objects, which are securable (with ACLs, allowing e.g. only specific SIDs to use them) and allow identification of the process on the other side of the connection. Individual messages are also securable: applications can set per-message SIDs, and also test for changes of the security context in the token associated with the (A)LPC message.
The typical communication scenario between the server and the client is as follows:
A server process first creates a named server connection port object, and waits for clients to connect.
A client requests a connection to that named port by sending a connect message.
If the server accepts the connection, two unnamed ports are created:
client communication port - used by client threads to communicate with a particular server
server communication port - used by the server to communicate with a particular client; one such port per client is cre
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https://en.wikipedia.org/wiki/Butyraldehyde
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Butyraldehyde, also known as butanal, is an organic compound with the formula CH3(CH2)2CHO. This compound is the aldehyde derivative of butane. It is a colorless flammable liquid with an unpleasant smell. It is miscible with most organic solvents.
Production
Butyraldehyde is produced almost exclusively by the hydroformylation of propylene:
CH3CH=CH2 + H2 + CO → CH3CH2CH2CHO
Traditionally, hydroformylation was catalyzed by cobalt carbonyl and later rhodium complexes of triphenylphosphine. The dominant technology involves the use of rhodium catalysts derived from the water-soluble ligand tppts. An aqueous solution of the rhodium catalyst converts the propylene to the aldehyde, which forms a lighter immiscible phase. About 6 billion kilograms are produced annually by hydroformylation. Butyraldehyde can be produced by the catalytic dehydrogenation of n-butanol. At one time, it was produced industrially by the catalytic hydrogenation of crotonaldehyde, which is derived from acetaldehyde.
Reactions
Butyraldehyde undergoes reactions typical of alkyl aldehydes, and these define many of the uses of this compound. Important reactions include hydrogenation to the alcohol, oxidation to the acid, and base-catalyzed condensation.
Uses
Aldol condensation in the presence of a base forms 2-ethyl-2-hexenal, which is then hydrogenated to form 2-ethylhexanol, a precursor to the plasticizer bis(2-ethylhexyl) phthalate.
Butyraldehyde is a precursor in the two-step synthesis of trimethylolpropane, which is used for the production of alkyd resins.
References
External links
Flavors
Alkanals
Foul-smelling chemicals
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https://en.wikipedia.org/wiki/Eric%20Hehner
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Eric "Rick" C. R. Hehner (born 16 September 1947) is a Canadian computer scientist. He was born in Ottawa. He studied mathematics and physics at Carleton University, graduating with a Bachelor of Science (B.Sc.) in 1969. He studied computer science at the University of Toronto, graduating with a Master of Science (M.Sc.) in 1970, and a Doctor of Philosophy (Ph.D.) in 1974. He then joined the faculty there, becoming a full professor in 1983. He became the Bell University Chair in software engineering in 2001, and retired in 2012.
Hehner's main research area is formal methods of software design. His method, initially called predicative programming, later called Practical Theory of Programming, is to consider each specification to be a binary (boolean) expression, and each programming construct to be a binary expression specifying the effect of executing the programming construct. Refinement is just implication. This is the simplest formal method, and the most general, applying to sequential, parallel, stand-alone, communicating, terminating, nonterminating, natural-time, real-time, deterministic, and probabilistic programs, and includes time and space bounds. This idea has influenced other computer science researchers, including Tony Hoare.
Hehner's other research areas include probabilistic programming, unified algebra, and high-level circuit design. In 1979, Hehner invented a generalization of radix complement called quote notation, which is a representation of the rational numbers that allows easier arithmetic and precludes roundoff error.
He was involved with developing international standards in programming and informatics, as a member of the International Federation for Information Processing (IFIP) IFIP Working Group 2.1 on Algorithmic Languages and Calculi, which specified, maintains, and supports the programming languages ALGOL 60 and ALGOL 68. and of IFIP Working Group 2.3 on Programming Methodology.
References
External links
DBLP publications
A Pra
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https://en.wikipedia.org/wiki/Prime%20signature
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In mathematics, the prime signature of a number is the multiset of (nonzero) exponents of its prime factorization. The prime signature of a number having prime factorization is the multiset .
For example, all prime numbers have a prime signature of {1}, the squares of primes have a prime signature of {2}, the products of 2 distinct primes have a prime signature of } and the products of a square of a prime and a different prime (e.g. 12, 18, 20, ...) have a prime signature of }.
Properties
The divisor function τ(n), the Möbius function μ(n), the number of distinct prime divisors ω(n) of n, the number of prime divisors Ω(n) of n, the indicator function of the squarefree integers, and many other important functions in number theory, are functions of the prime signature of n.
In particular, τ(n) equals the product of the incremented by 1 exponents from the prime signature of n.
For example, 20 has prime signature {2,1} and so the number of divisors is (2+1) × (1+1) = 6. Indeed, there are six divisors: 1, 2, 4, 5, 10 and 20.
The smallest number of each prime signature is a product of primorials. The first few are:
1, 2, 4, 6, 8, 12, 16, 24, 30, 32, 36, 48, 60, 64, 72, 96, 120, 128, 144, 180, 192, 210, 216, ... .
A number cannot divide another unless its prime signature is included in the other numbers prime signature in the Young's lattice.
Numbers with same prime signature
Sequences defined by their prime signature
Given a number with prime signature S, it is
A prime number if S = {1},
A square if gcd S is even,
A cube if gcd S is divisible by 3,
A square-free integer if max S = 1,
A cube-free integer if max S ≤ 2,
A powerful number if min S ≥ 2,
A perfect power if gcd S > 1,
An Achilles number if min S ≥ 2 and gcd S = 1,
k-almost prime if sum S = k.
See also
Canonical representation of a positive integer
References
External links
List of the first 400 prime signatures
Iterative Mapping of Prime Signatures
Number theory
Prime numbers
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https://en.wikipedia.org/wiki/Symmetry%20%28physics%29
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In physics, a symmetry of a physical system is a physical or mathematical feature of the system (observed or intrinsic) that is preserved or remains unchanged under some transformation.
A family of particular transformations may be continuous (such as rotation of a circle) or discrete (e.g., reflection of a bilaterally symmetric figure, or rotation of a regular polygon). Continuous and discrete transformations give rise to corresponding types of symmetries. Continuous symmetries can be described by Lie groups while discrete symmetries are described by finite groups (see Symmetry group).
These two concepts, Lie and finite groups, are the foundation for the fundamental theories of modern physics. Symmetries are frequently amenable to mathematical formulations such as group representations and can, in addition, be exploited to simplify many problems.
Arguably the most important example of a symmetry in physics is that the speed of light has the same value in all frames of reference, which is described in special relativity by a group of transformations of the spacetime known as the Poincaré group. Another important example is the invariance of the form of physical laws under arbitrary differentiable coordinate transformations, which is an important idea in general relativity.
As a kind of invariance
Invariance is specified mathematically by transformations that leave some property (e.g. quantity) unchanged. This idea can apply to basic real-world observations. For example, temperature may be homogeneous throughout a room. Since the temperature does not depend on the position of an observer within the room, we say that the temperature is invariant under a shift in an observer's position within the room.
Similarly, a uniform sphere rotated about its center will appear exactly as it did before the rotation. The sphere is said to exhibit spherical symmetry. A rotation about any axis of the sphere will preserve how the sphere "looks".
Invariance in force
The above
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https://en.wikipedia.org/wiki/John%20C.%20Reynolds
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John Charles Reynolds (June 1, 1935 – April 28, 2013) was an American computer scientist.
Education and affiliations
John Reynolds studied at Purdue University and then earned a Doctor of Philosophy (Ph.D.) in theoretical physics from Harvard University in 1961. He was a professor of information science at Syracuse University from 1970 to 1986. From then until his death, he was a professor of computer science at Carnegie Mellon University. He also held visiting positions at Aarhus University (Denmark), The University of Edinburgh, Imperial College London, Microsoft Research (Cambridge, UK) and Queen Mary University of London.
Academic work
Reynolds's main research interest was in the area of programming language design and associated specification languages, especially concerning formal semantics. He invented the polymorphic lambda calculus (System F) and formulated the property of semantic parametricity; the same calculus was independently discovered by Jean-Yves Girard. He wrote a seminal paper on definitional interpreters, which clarified early work on continuations and introduced the technique of defunctionalization. He applied category theory to programming language semantics. He defined the programming languages Gedanken and Forsythe, known for their use of intersection types. He worked on a separation logic to describe and reason about shared mutable data structures.
Reynolds created an elegant, idealized formulation of the programming language ALGOL, which exhibits ALGOL's syntactic and semantic purity, and is used in programming language research. It also made a convincing methodologic argument regarding the suitability of local effects in the context of call-by-name languages, in contrast with the global effects used by call-by-value languages such as ML. The conceptual integrity of the language made it one of the main objects of semantic research, along with Programming Computable Functions (PCF) and ML.
He was an editor of journals such as the Commun
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https://en.wikipedia.org/wiki/Kahlenberg%20Transmitter
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The Kahlenberg Transmitter is a facility for FM- and TV on the Kahlenberg near Vienna. It was established in 1953 and used until 1956 an antenna on the observation tower Stefaniewarte. From 1956 to 1974 a 129-metre-high guyed mast built of lattice steel was used. Since 1974 a 165-metre-high guyed steel tube mast has been used, which is equipped with rooms of technical equipment.
See also
List of masts
References
External links
http://www.skyscraperpage.com/diagrams/?b10351
Radio masts and towers in Europe
Towers in Austria
Broadcast transmitters
Observation towers
1953 establishments in Austria
Towers completed in 1953
20th-century architecture in Austria
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https://en.wikipedia.org/wiki/Primefree%20sequence
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In mathematics, a primefree sequence is a sequence of integers that does not contain any prime numbers. More specifically, it usually means a sequence defined by the same recurrence relation as the Fibonacci numbers, but with different initial conditions causing all members of the sequence to be composite numbers that do not all have a common divisor. To put it algebraically, a sequence of this type is defined by an appropriate choice of two composite numbers a1 and a2, such that the greatest common divisor is equal to 1, and such that for there are no primes in the sequence of numbers calculated from the formula
.
The first primefree sequence of this type was published by Ronald Graham in 1964.
Wilf's sequence
A primefree sequence found by Herbert Wilf has initial terms
The proof that every term of this sequence is composite relies on the periodicity of Fibonacci-like number sequences modulo the members of a finite set of primes. For each prime , the positions in the sequence where the numbers are divisible by repeat in a periodic pattern, and different primes in the set have overlapping patterns that result in a covering set for the whole sequence.
Nontriviality
The requirement that the initial terms of a primefree sequence be coprime is necessary for the question to be non-trivial. If the initial terms share a prime factor (e.g., set and for some and both greater than 1), due to the distributive property of multiplication and more generally all subsequent values in the sequence will be multiples of . In this case, all the numbers in the sequence will be composite, but for a trivial reason.
The order of the initial terms is also important. In Paul Hoffman's biography of Paul Erdős, The man who loved only numbers, the Wilf sequence is cited but with the initial terms switched. The resulting sequence appears primefree for the first hundred terms or so, but term 138 is the 45-digit prime .
Other sequences
Several other primefree sequences are known:
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https://en.wikipedia.org/wiki/ISO%2011783
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ISO 11783, known as Tractors and machinery for agriculture and forestry—Serial control and communications data network (commonly referred to as "ISO Bus" or "ISOBUS") is a communication protocol for the agriculture industry based on the SAE J1939 protocol (which includes CANbus) .
It is managed by the ISOBUS group in VDMA.
The ISOBUS standard specifies a serial data network for control and communications on forestry or agricultural tractors and implements.
Parts
The standard comes in 14 parts:
ISO 11783-175388: General standard for mobile data communication
ISO 18883-2: Physical layer
ISO 11783-3: Data link layer
ISO 11783-4: Network layer
ISO 11783-5: Network management
ISO 11783-6: Virtual terminal
ISO 11783-7: Implement messages application layer
ISO 11783-8: Power train messages
ISO 11783-9: Tractor ECU
ISO 11783-10: Task controller and management information system data interchange
ISO 11783-11: Mobile data element dictionary
ISO 11783-12: Diagnostics services
ISO 11783-13: File server
ISO 11783-14: Sequence control
Agricultural Industry Electronics Foundation and ISOBUS
The Agricultural Industry Electronics Foundation works to promote ISOBUS and coordinate enhanced certification tests for the ISO 11783 standard.
External links
ISO 11783-1:2017
Official VDMA page for ISOBUS
Open-source PoolEdit editor for creating ISOBUS user interfaces
11783
Network protocols
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https://en.wikipedia.org/wiki/Intraspecific%20competition
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Intraspecific competition is an interaction in population ecology, whereby members of the same species compete for limited resources. This leads to a reduction in fitness for both individuals, but the more fit individual survives and is able to reproduce.
By contrast, interspecific competition occurs when members of different species compete for a shared resource. Members of the same species have rather similar requirements for resources, whereas different species have a smaller contested resource overlap, resulting in intraspecific competition generally being a stronger force than interspecific competition.
Individuals can compete for food, water, space, light, mates, or any other resource which is required for survival or reproduction. The resource must be limited for competition to occur; if every member of the species can obtain a sufficient amount of every resource then individuals do not compete and the population grows exponentially. Prolonged exponential growth is rare in nature because resources are finite and so not every individual in a population can survive, leading to intraspecific competition for the scarce resources.
When resources are limited, an increase in population size reduces the quantity of resources available for each individual, reducing the per capita fitness in the population. As a result, the growth rate of a population slows as intraspecific competition becomes more intense, making it a negatively density dependent process. The falling population growth rate as population increases can be modelled effectively with the logistic growth model. The rate of change of population density eventually falls to zero, the point ecologists have termed the carrying capacity (K). However, a population can only grow to a very limited number within an environment. The carrying capacity, defined by the variable k, of an environment is the maximum number of individuals or species an environment can sustain and support over a longer period of time. The r
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https://en.wikipedia.org/wiki/Pablo%20Emilio%20Madero
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Pablo Emilio Madero Belden (August 3, 1921 – March 16, 2007) was a Mexican politician. He was the 13th president of the National Action Party (PAN, 1984–1987) and former presidential candidate who represented both the PAN and the extinct Mexican Democratic Party (in Spanish: Partido Demócrata Mexicano, PDM).
Pablo Emilio Madero Belden was the son of General Emilio Madero González and Mercedes Belden Gutiérrez. He graduated as a chemical engineer from the National Autonomous University of Mexico in 1945 as a Sugar and Oil specialist. Six years earlier, in 1939, he had joined the National Action Party (PAN) on December 6, 1939 as a youth group member, an institution he represented twice in the Chamber of Deputies and presided both locally and nationally before leaving it in the early 1990s. He was Vice-President of the National Transformation Industry Chamber (CANACINTRA) and President of the Glass Producers Association of Latin America, among other charges.
Madero Belden left the PAN in 1991. In 1994, he became a presidential candidate of Mexican Democratic Party but he lost with 97,935 votes or 0.28 percent of the total votes.
Madero Belden was married to Norma Morelos Zaragoza Luquin, with whom he had eight children: Norma Alicia, Pablo, Marcela, Leticia, Mercedes, Mónica, Guillermo and Jorge.
In 2007 Pablo Emilio Madero died at the age of 85, in Monterrey, Nuevo León, México.
References
Diccionario biográfico del gobierno mexicano, Ed. Fondo de Cultura Económica, Mexico, 1992.
1921 births
2007 deaths
Politicians from San Pedro, Coahuila
Members of the Chamber of Deputies (Mexico)
Candidates in the 1982 Mexican presidential election
Candidates in the 1994 Mexican presidential election
Presidents of the National Action Party (Mexico)
National Autonomous University of Mexico alumni
Mexican Democratic Party politicians
20th-century Mexican politicians
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https://en.wikipedia.org/wiki/Channel%20use
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Channel use is a quantity used in signal processing or telecommunication related to symbol rate and channel capacity. Capacity is measured in bits per input symbol into the channel (bits per channel use). If a symbol enters the channel every Ts seconds (for every symbol period a symbol is transmitted) the channel capacity in bits per second is C/Ts. The phrase "1 bit per channel use" denotes the transmission of 1 symbol (of duration Ts) containing 1 data bit.
See also
Adaptive communications
End instrument
Spectral efficiency and modulation efficiency in (bit/s)/Hz
Data transmission
Information theory
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https://en.wikipedia.org/wiki/Pidgeon%20process
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The Pidgeon process is a practical method for smelting magnesium. The most common method involves the raw material, dolomite being fed into an externally heated reduction tank and then thermally reduced to metallic magnesium using 75% ferrosilicon as a reducing agent in a vacuum. Overall the processes in magnesium smelting via the Pidgeon process involve dolomite calcination, grinding and pelleting, and vacuum thermal reduction. Besides the Pidgeon process, electrolysis of magnesium chloride for commercial production of magnesium is also used, at one point in time accounting for 75% of the world's magnesium production.
Chemistry
The general reaction that occurs in the Pidgeon process is:
2MgO*CaO + Si(Fe) -> 2Mg +Ca2SiO4
For industrial use, ferrosilicon is used because its cheaper and more readily available than silicon. The iron from the alloy is a spectator in the reaction. CaC2 may also be used as an even cheaper alternative for silicon and ferrosilicon, but is disadvantageous because it decreases the magnesium yield slightly.
The magnesium raw material of this type of reaction is magnesium oxide, which is obtained in many ways. In all cases, the raw materials have to be calcined to remove both water and carbon dioxide. Without doing so, the reaction would be gaseous at reaction temperatures and may even revert the reaction. Magnesium oxide can be obtained by sea or lake water magnesium chloride hydrolyzed to hydroxide. It is calcined to magnesium oxide by removing water. Another option is to use mined magnesite (MgCO3) calcined to magnesium oxide by carbon dioxide removal.
The most used raw material is mined dolomite, a mixed (Ca,Mg)CO3, where the calcium oxide present in the reaction zone scavenges the silica formed, releasing heat and consuming one of the products, ultimately helping push the equilibrium to the right.
(1) Dolomite calcination
CaCO3*MgCO3 -> MgO*CaO +2CO2
(2) Reduction
2MgO*CaO +Si(Fe) -> 2Mg + Ca2SiO4
The Pidgeon process is an endoth
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https://en.wikipedia.org/wiki/Computational%20epidemiology
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Computational epidemiology is a multidisciplinary field that uses techniques from computer science, mathematics, geographic information science and public health to better understand issues central to epidemiology such as the spread of diseases or the effectiveness of a public health intervention. Computational epidemiology traces its origins to mathematical epidemiology, but began to experience significant growth with the rise of big data and the democratization of high-performance computing through cloud computing.
Introduction
In contrast with traditional epidemiology, computational epidemiology looks for patterns in unstructured sources of data, such as social media. It can be thought of as the hypothesis-generating antecedent to hypothesis-testing methods such as national surveys and randomized controlled trials.
A mathematical model is developed which describes the observed behavior of the viruses, based on the available data. Then simulations of the model are performed to understand the possible outcomes given the model used. These simulations produce as results projections which can then be used to make predictions or verify the facts and then be used to plan interventions and meters towards the control of the disease's spread.
References
External links
Sax Institute - Decision Analytics
Computational science
Epidemiology
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https://en.wikipedia.org/wiki/Team%20OS/2
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Team OS/2 was an advocacy group formed to promote IBM's OS/2 operating system. Originally internal to IBM with no formal IBM support, Team OS/2 successfully converted to a grassroots movement formally supported (but not directed) by IBM - consisting of well over ten thousand OS/2 enthusiasts both within and without IBM. It is one of the earliest examples of both an online viral phenomenon and a cause attracting supporters primarily through online communications.
The decline of Team OS/2 largely coincided with IBM's abandonment of OS/2 and the coinciding attacks orchestrated by Microsoft on OS/2, Team OS/2, and IBM's early attempts at online evangelism.
History
Beginnings
Team OS/2 was a significant factor in the spread and acceptance of OS/2. Formed in February 1992, Team OS/2 began when IBM employee Dave Whittle, recently appointed by IBM to evangelize OS/2 online, formed an internal IBM discussion group titled TEAMOS2 FORUM on IBM's worldwide network, which at the time, served more individuals than did the more academic Internet.
The forum header stated that its purpose was
The forum went viral as increasing numbers of IBMers worldwide began to contribute a wide variety of ideas as to how IBM could effectively compete with Microsoft to establish OS/2 as the industry standard desktop operating system. Within a short time, thousands of IBM employees had added the words TEAMOS2 to their internet phone directory listing, which enabled anyone within IBM to find like-minded OS/2 enthusiasts within the company and work together to overcome the challenges posed by IBM's size, insularity, and top-down marketing style. TEAMOS2 FORUM quickly caught the attention of some IBM executives, including Lee Reiswig and Lucy Baney, who after initial scepticism, offered moral and financial support for Whittle's grass roots and online marketing efforts. IBM's official program for generating word-of-mouth enthusiasm was called the "OS/2 Ambassador Program", where OS/2 enthusias
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https://en.wikipedia.org/wiki/WWJE-DT
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WWJE-DT (channel 50) is a television station licensed to Derry, New Hampshire, United States, serving the Boston area as an affiliate of True Crime Network. It is owned by TelevisaUnivision alongside Marlborough, Massachusetts–licensed Univision-owned station WUNI (channel 66). The two stations share main studios and transmitter facilities on Parmenter Road in Hudson, Massachusetts. WWJE is operated separately from WUNI's joint sales agreement (JSA) with Entravision Communications–owned UniMás affiliate WUTF-TV (channel 27) in Worcester.
WWJE formerly broadcast local newscasts from a studio located in Concord, branded as the NH1 News Network or NH1 News. Besides WBIN, sister radio station WNNH also used the NH1 News branding from August 2015 to August 2017. WBIN-TV was one of only two television stations based in the state of New Hampshire to broadcast local newscasts (alongside WMUR-TV), as much of the state is part of the Boston media market. On February 17, 2017, WBIN canceled its newscasts as part of a wind-down of the station's operations following the sale of its spectrum in the Federal Communications Commission (FCC)'s incentive auction.
The station shut down its channel 35 transmitter on Merrill Hill in Hudson, New Hampshire on September 15, 2017, and began operating on channel 27 through a channel sharing agreement with channel 66 (then WUTF-DT); the WBIN-TV license was subsequently sold by Carlisle One Media, a company controlled by Bill Binnie, to WUNI's owner, Univision Communications.
History
Prior history of channel 50 in Boston
The channel 50 allocation in the Boston market originally belonged to WXPO-TV, which launched in October 1969. It operated from two studios: its offices and master production facilities were located on Dutton Street in downtown Lowell, Massachusetts; however, its transmitter and "main" studio was on Governor Dinsmore Road in Windham, New Hampshire, to comply with FCC regulations requiring that a station's transmitter be l
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https://en.wikipedia.org/wiki/Diane%20Pozefsky
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Diane P. Pozefsky is a research professor at the University of North Carolina in the department of Computer Science. Pozefsky was awarded the Women in Technology International (WITI) 2011 Hall of Fame Award for contributions to the fields of Science and Technology.
Education
Pozefsky earned a A.B in applied mathematics from Brown University in 1972 and her Ph.D. from the Department of Computer Science at UNC in 1979 under the tutelage of Doctor Mehdi Jazayeri.
Career
Pozefsky joined IBM Corporation, Raleigh, NC, in 1979 as a member of the Communication Systems Architecture Department working in the specification and application of the Systems Network Architecture (SNA), a large and complex feature-rich network architecture developed in the 1970s by IBM. Similar in some respects to the OSI reference model, but with a number of differences. SNA is essentially composed of seven layers. She worked for IBM for 25 years and was named an IBM Fellow in 1994 in recognition of her work on APPN and AnyNet architectures and development. She was tasked with the network and application design for the 1998 and 2000 Olympics. Her work life has largely been focused on networking and software engineering, including:
developing networking protocols
deploying the network at the Nagano Olympics
development processes
storage networking
application development
mobile computing
She has worked in development, design, and architecture and two areas that she has become particularly interested in later in here career are improving quality and blending theory and practice.
Dr. Diane Pozefsky returned to UNC after retiring from IBM in June 2004.
Publications
Pozefsky's publications include:
“Storage Networking: More than an SNA Anagram” in NCP and 3745/46 Today, Summer 2001.
“MPTN Transport Gateway”, with D. Ogle in SNA and TCP/IP Enterprise Networking, Manning Publications Co, 1997.
“Multiprotocol Transport Networking: Eliminating Application Dependencies on Communications Prot
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https://en.wikipedia.org/wiki/Tissot%27s%20indicatrix
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In cartography, a Tissot's indicatrix (Tissot indicatrix, Tissot's ellipse, Tissot ellipse, ellipse of distortion) (plural: "Tissot's indicatrices") is a mathematical contrivance presented by French mathematician Nicolas Auguste Tissot in 1859 and 1871 in order to characterize local distortions due to map projection. It is the geometry that results from projecting a circle of infinitesimal radius from a curved geometric model, such as a globe, onto a map. Tissot proved that the resulting diagram is an ellipse whose axes indicate the two principal directions along which scale is maximal and minimal at that point on the map.
A single indicatrix describes the distortion at a single point. Because distortion varies across a map, generally Tissot's indicatrices are placed across a map to illustrate the spatial change in distortion. A common scheme places them at each intersection of displayed meridians and parallels. These schematics are important in the study of map projections, both to illustrate distortion and to provide the basis for the calculations that represent the magnitude of distortion precisely at each point. Because all ellipses on the map occupy the same area, the distortion imposed by the map projection is evident.
There is a one-to-one correspondence between the Tissot indicatrix and the metric tensor of the map projection coordinate conversion.
Description
Tissot's theory was developed in the context of cartographic analysis. Generally the geometric model represents the Earth, and comes in the form of a sphere or ellipsoid.
Tissot's indicatrices illustrate linear, angular, and areal distortions of maps:
A map distorts distances (linear distortion) wherever the quotient between the lengths of an infinitesimally short line as projected onto the projection surface, and as it originally is on the Earth model, deviates from 1. The quotient is called the scale factor. Unless the projection is conformal at the point being considered, the scale factor varies
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https://en.wikipedia.org/wiki/Polarizer
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A polarizer or polariser (see spelling differences) is an optical filter that lets light waves of a specific polarization pass through while blocking light waves of other polarizations. It can filter a beam of light of undefined or mixed polarization into a beam of well-defined polarization, that is polarized light. The common types of polarizers are linear polarizers and circular polarizers. Polarizers are used in many optical techniques and instruments, and polarizing filters find applications in photography and LCD technology. Polarizers can also be made for other types of electromagnetic waves besides visible light, such as radio waves, microwaves, and X-rays.
Linear polarizers
Linear polarizers can be divided into two general categories: absorptive polarizers, where the unwanted polarization states are absorbed by the device, and beam-splitting polarizers, where the unpolarized beam is split into two beams with opposite polarization states. Polarizers which maintain the same axes of polarization with varying angles of incidence are often called Cartesian polarizers, since the polarization vectors can be described with simple Cartesian coordinates (for example, horizontal vs. vertical) independent from the orientation of the polarizer surface. When the two polarization states are relative to the direction of a surface (usually found with Fresnel reflection), they are usually termed s and p. This distinction between Cartesian and s–p polarization can be negligible in many cases, but it becomes significant for achieving high contrast and with wide angular spreads of the incident light.
Absorptive polarizers
Certain crystals, due to the effects described by crystal optics, show dichroism, preferential absorption of light which is polarized in particular directions. They can therefore be used as linear polarizers. The best known crystal of this type is tourmaline. However, this crystal is seldom used as a polarizer, since the dichroic effect is strongly wavelen
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https://en.wikipedia.org/wiki/ProClarity
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ProClarity Corporation was a software company specializing in business intelligence and data analysis applications.
The company was founded in 1995 as Knosys Inc. in Boise, Idaho. The company was renamed ProClarity after its primary commercial software product, "ProClarity", in 2001.
ProClarity's software products integrated tightly with Microsoft Analysis Services.
Among ProClarity's more than 2,000 global clients were AT&T, Ericsson, Hewlett-Packard, Home Depot, Pennzoil QuakerState, Reckitt Benckiser, Roche, Siemens, USDA, Verizon, and Wells Fargo.
On April 3, 2006, Microsoft announced the acquisition of ProClarity. The company was gradually folded into Microsoft's Business Division while a final update to the software product, version 6.3, was released in 2007. Additional business intelligence components, such as PerformancePoint Services for SharePoint 2010, and business intelligence improvements in Excel were released by the division in subsequent years.
References
External links
Microsoft business intelligence
Business intelligence companies
Former Microsoft subsidiaries
Business services companies established in 1995
Online analytical processing
Companies based in Boise, Idaho
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https://en.wikipedia.org/wiki/Group%20code
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In coding theory, group codes are a type of code. Group codes consist of
linear block codes which are subgroups of , where is a finite Abelian group.
A systematic group code is a code over of order defined by homomorphisms which determine the parity check bits. The remaining bits are the information bits themselves.
Construction
Group codes can be constructed by special generator matrices which resemble generator matrices of linear block codes except that the elements of those matrices are endomorphisms of the group instead of symbols from the code's alphabet. For example, considering the generator matrix
the elements of this matrix are matrices which are endomorphisms. In this scenario, each codeword can be represented as
where are the generators of .
See also
Group coded recording (GCR)
References
Further reading
Coding theory
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https://en.wikipedia.org/wiki/Genetic%20distance
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Genetic distance is a measure of the genetic divergence between species or between populations within a species, whether the distance measures time from common ancestor or degree of differentiation. Populations with many similar alleles have small genetic distances. This indicates that they are closely related and have a recent common ancestor.
Genetic distance is useful for reconstructing the history of populations, such as the multiple human expansions out of Africa. It is also used for understanding the origin of biodiversity. For example, the genetic distances between different breeds of domesticated animals are often investigated in order to determine which breeds should be protected to maintain genetic diversity.
Biological foundation
In the genome of an organism, each gene is located at a specific place called the locus for that gene. Allelic variations at these loci cause phenotypic variation within species (e.g. hair colour, eye colour). However, most alleles do not have an observable impact on the phenotype. Within a population new alleles generated by mutation either die out or spread throughout the population. When a population is split into different isolated populations (by either geographical or ecological factors), mutations that occur after the split will be present only in the isolated population. Random fluctuation of allele frequencies also produces genetic differentiation between populations. This process is known as genetic drift. By examining the differences between allele frequencies between the populations and computing genetic distance, we can estimate how long ago the two populations were separated.
Measures
Although it is simple to define genetic distance as a measure of genetic divergence, there are several different statistical measures that have been proposed. This has happened because different authors considered different evolutionary models. The most commonly used are Nei's genetic distance, Cavalli-Sforza and Edwards measure, an
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https://en.wikipedia.org/wiki/Replication%20%28computing%29
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Replication in computing involves sharing information so as to ensure consistency between redundant resources, such as software or hardware components, to improve reliability, fault-tolerance, or accessibility.
Terminology
Replication in computing can refer to:
Data replication, where the same data is stored on multiple storage devices
Computation replication, where the same computing task is executed many times. Computational tasks may be:
Replicated in space, where tasks are executed on separate devices
Replicated in time, where tasks are executed repeatedly on a single device
Replication in space or in time is often linked to scheduling algorithms.
Access to a replicated entity is typically uniform with access to a single non-replicated entity. The replication itself should be transparent to an external user. In a failure scenario, a failover of replicas should be hidden as much as possible with respect to quality of service.
Computer scientists further describe replication as being either:
Active replication, which is performed by processing the same request at every replica
Passive replication, which involves processing every request on a single replica and transferring the result to the other replicas
When one leader replica is designated via leader election to process all the requests, the system is using a primary-backup or primary-replica scheme, which is predominant in high-availability clusters. In comparison, if any replica can process a request and distribute a new state, the system is using a multi-primary or multi-master scheme. In the latter case, some form of distributed concurrency control must be used, such as a distributed lock manager.
Load balancing differs from task replication, since it distributes a load of different computations across machines, and allows a single computation to be dropped in case of failure. Load balancing, however, sometimes uses data replication (especially multi-master replication) internally, to distrib
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https://en.wikipedia.org/wiki/Synchronization%20in%20telecommunications
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Many services running on modern digital telecommunications networks require accurate synchronization for correct operation. For example, if telephone exchanges are not synchronized, then bit slips will occur and degrade performance. Telecommunication networks rely on the use of highly accurate primary reference clocks which are distributed network-wide using synchronization links and synchronization supply units.
Ideally, clocks in a telecommunications network are synchronous, controlled to run at identical rates, or at the same mean rate with a fixed relative phase displacement, within a specified limited range. However, they may be mesochronous in practice. In common usage, mesochronous networks are often described as synchronous.
Components
Primary reference clock (PRC)
Modern telecommunications networks use highly accurate primary master clocks that must meet the international standards requirement for long term frequency accuracy better than 1 part in 1011. To get this performance, atomic clocks or GPS disciplined oscillators are normally used.
Synchronization supply unit
Synchronization supply units (SSU) are used to ensure reliable synchronisation distribution. They have a number of key functions:
They filter the synchronisation signal they receive to remove the higher frequency phase noise.
They provide distribution by providing a scalable number of outputs to synchronise other local equipment.
They provide a capability to carry on producing a high quality output even when their input reference is lost, this is referred to as holdover mode.
Quality metrics
In telecoms networks two key parameters are used for measurement of synchronisation performance. These parameters are defined by the International Telecommunication Union in its recommendation G.811, by European Telecommunications Standards Institute in its standard EN 300 462-1-1, by the ANSI Synchronization Interface Standard T1.101 defines profiles for clock accuracy at each stratum level, and b
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https://en.wikipedia.org/wiki/Godavari%20River%20Basin%20Irrigation%20Projects
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The Godavari River has its catchment area in seven states of India: Maharashtra, Telangana, Chhattisgarh, Madhya Pradesh, Andhra Pradesh, Karnataka and Odisha. The number of dams constructed in Godavari basin is the highest among all the river basins in India. Nearly 350 major and medium dams and barrages had been constructed in the river basin by the year 2012.
Jalaput
Chintalapudi lift
Uttarrandhra Sujala Sravanthi lift
Balimela Reservoir
Upper Kolab
Dummugudem Lift Irrigation Schemes
Nizam Sagar
Sriram Sagar or Pochampadu
Kakatiya Canal
SRSP Flood Flow Canal
Manjara Dam
Manjira Reservoir
Singur Dam
Shanigaram Reservoir
Lower Manair Dam
Mid Manair Dam
Upper Manair Dam
Yellampally
Taliperu Project
Babli barrage or Babhali
Devadula lift irrigation project
Polavaram Project
Inchampalli Project
Sadarmat
Alisagar lift irrigation scheme
Kaddam
Sri Komaram Bheem Project
Lower Tirna
Siddeshwar or Purna
Yeldari Dam
Godavari Canal
Mula Dam
Bhandardara Dam
Isapur Dam or Upper Penganga
Upper Dudhana Dam
Jayakwadi or Paithan
Upper Pravara
Upper Indravati dam
Upper Wain Ganga (Bheemgarh Dam)
Upper Wardha Dam
Lower Wardha Dam
Majalgaon Dam
Ghatghar Dam
Upper Vaitarana Dam
Vishnupuri Barrage
Sirpur Dam or Bagh reservoir
Gosi kd Dam or Gosi Kund dam
Totladoh Dam
Yeldari Dam
Kamthikhairy Dam or Pench dam
Erai Dam
Tultuli Dam
Arunawati Dam
Lower Wunna Dam or Wadgaon
Manar Dam
Lower Pus Dam
Ramtek Dam
Pench diversion Project, Madhya Pradesh
See also
River Basins in Madhya Pradesh
Godavari Water Disputes Tribunal
List of dams and reservoirs in Maharashtra
List of dams and reservoirs in Andhra Pradesh
List of dams and reservoirs in Telangana
List of dams and reservoirs in India
External links
For Irrigation Projects in Maharashtra, refer to http://www.mahagovid.org/maha_dams.htm
The Majalgaon dynamic regulation pilot project
https://web.archive.org/web/20050404205051/http://ceamt.vidcngp.com/pro/index.htm
https://web.arc
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https://en.wikipedia.org/wiki/Industrial%20fermentation
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Industrial fermentation is the intentional use of fermentation in manufacturing processes. In addition to the mass production of fermented foods and drinks, industrial fermentation has widespread applications in chemical industry. Commodity chemicals, such as acetic acid, citric acid, and ethanol are made by fermentation. Moreover, nearly all commercially produced industrial enzymes, such as lipase, invertase and rennet, are made by fermentation with genetically modified microbes. In some cases, production of biomass itself is the objective, as is the case for single-cell proteins, baker's yeast, and starter cultures for lactic acid bacteria used in cheesemaking.
In general, fermentations can be divided into four types:
Production of biomass (viable cellular material)
Production of extracellular metabolites (chemical compounds)
Production of intracellular components (enzymes and other proteins)
Transformation of substrate (in which the transformed substrate is itself the product)
These types are not necessarily disjoined from each other, but provide a framework for understanding the differences in approach. The organisms used are typically microorganisms, particularly bacteria, algae, and fungi, such as yeasts and molds, but industrial fermentation may also involve cell cultures from plants and animals, such as CHO cells and insect cells. Special considerations are required for the specific organisms used in the fermentation, such as the dissolved oxygen level, nutrient levels, and temperature. The rate of fermentation depends on the concentration of microorganisms, cells, cellular components, and enzymes as well as temperature, pH and level of oxygen for aerobic fermentation. Product recovery frequently involves the concentration of the dilute solution.
General process overview
In most industrial fermentations, the organisms or eukaryotic cells are submerged in a liquid medium; in others, such as the fermentation of cocoa beans, coffee cherries, and miso,
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https://en.wikipedia.org/wiki/Loop%20bin%20duplicator
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A loop bin duplicator is a specialized audio tape machine used in the duplication of pre-recorded audio cassettes and 8-track cartridges.
Loop bin duplicators were first introduced in the early 1990s.
They had fewer moving parts than previous systems, so were more reliable to operate.
Analog loop bin duplicator
An analog loop bin uses a long loop of either 1/2" wide (for cassette duplication) or 1" wide (for 8-track tape duplication) loaded in a large bin located in the front of the duplicator. This loop master tape is loaded into the duplicator's bin from a traditional open-reel of tape, where the program material has been recorded to it using a studio-type multitrack tape recorder in real-time beforehand. The loop tape for cassette duplication has 4 tracks on the loop bin master tape (2 stereo tracks for Side A recorded in one direction, and the other 2 for Side B recorded in the opposite direction), and for 8-tracks has all of the 8 tracks (4 2-track stereo programs) recorded in one direction. The loop-bin master tape is read by the duplicator at a very high speed. For cassettes, either 32, 64, 80, or 100 times the normal speed of playback (1.875 ips) of an audio cassette (60, 120, 150, and 187.5 ips respectively) is used, and 10 or 20 times the normal speed of playback (3.75 ips) is used for 8-track duplication (37.50 and 75 ips respectively).
While this loop is being played back, the audio signals for the A and B side (or all 4 programs for 8-track) are sent to a "slave" recorder or an audio bus that contains multiple "slaves". The "slave" records from the loop bin master tape the 4 tracks for both A and B sides to an open-faced "pancake" reel (similar to motion picture film wound on a plastic core) of raw 1/8" audio tape (for cassettes), or all 8 tape tracks to back-lubricated 1/4" audio tape (for 8-track cartridges) also wound on a "pancake" reel, at the same high speed. After it is recorded, this pancake of tape is then loaded onto special machin
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https://en.wikipedia.org/wiki/Resolution%20%28logic%29
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In mathematical logic and automated theorem proving, resolution is a rule of inference leading to a refutation-complete theorem-proving technique for sentences in propositional logic and first-order logic. For propositional logic, systematically applying the resolution rule acts as a decision procedure for formula unsatisfiability, solving the (complement of the) Boolean satisfiability problem. For first-order logic, resolution can be used as the basis for a semi-algorithm for the unsatisfiability problem of first-order logic, providing a more practical method than one following from Gödel's completeness theorem.
The resolution rule can be traced back to Davis and Putnam (1960); however, their algorithm required trying all ground instances of the given formula. This source of combinatorial explosion was eliminated in 1965 by John Alan Robinson's syntactical unification algorithm, which allowed one to instantiate the formula during the proof "on demand" just as far as needed to keep refutation completeness.
The clause produced by a resolution rule is sometimes called a resolvent.
Resolution in propositional logic
Resolution rule
The resolution rule in propositional logic is a single valid inference rule that produces a new clause implied by two clauses containing complementary literals. A literal is a propositional variable or the negation of a propositional variable. Two literals are said to be complements if one is the negation of the other (in the following,
is taken to be the complement to ). The resulting clause contains all the literals that do not have complements.
Formally:
where
all , , and are literals,
the dividing line stands for "entails".
The above may also be written as:
Or schematically as:
We have the following terminology:
The clauses and are the inference's premises
(the resolvent of the premises) is its conclusion.
The literal is the left resolved literal,
The literal is the right resolved literal,
is the resolved atom or
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https://en.wikipedia.org/wiki/Specman
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Specman is an EDA tool that provides advanced automated functional verification of hardware designs. It provides an environment for working with, compiling, and debugging testbench environments written in the e Hardware Verification Language. Specman also offers automated testbench generation to boost productivity in the context of block, chip, and system verification.
The Specman tool itself does not include an HDL simulator (for design languages such as VHDL or Verilog.) To simulate an e-testbench with a design written in VHDL/Verilog, Specman must be run in conjunction with a separate HDL simulation tool. Specman is a feature of Cadence's new Xcelium simulator, where tighter product integration offers both faster runtime performance and debugs capabilities not available with other HDL simulators. In principle, Specman can co-simulate with any HDL simulator supporting standard PLI or VHPI interface, such as Synopsys's VCS, or Mentor's Questa.
History
Specman was originally developed at Verisity, an Israel-based company, which was acquired by Cadence on April 7, 2005.
It is now part of Cadence's functional verification suite.
References
Hardware verification languages
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https://en.wikipedia.org/wiki/Swain%20equation
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The Swain equation relates the kinetic isotope effect for the protium/tritium combination with that of the protium/deuterium combination according to:
where kH,D,T are the reaction rate constants for the protonated, deuterated and tritiated reactants respectively.
External links
Applied Swain equation
References
Use of Hydrogen Isotope Effects to Identify the Attacking Nucleophile in the Enolization of Ketones Catalyzed by Acetic Acid C. Gardner Swain, Edward C. Stivers, Joseph F. Reuwer, Jr. Lawrence J. Schaad; J. Am. Chem. Soc.; 1958; 80(21); 5885-5893. First Page
Chemical kinetics
Equations
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https://en.wikipedia.org/wiki/Machin-like%20formula
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In mathematics, Machin-like formulae are a popular technique for computing (the ratio of the circumference to the diameter of a circle) to a large number of digits. They are generalizations of John Machin's formula from 1706:
which he used to compute to 100 decimal places.
Machin-like formulas have the form
where is a positive integer, are signed non-zero integers, and and are positive integers such that .
These formulas are used in conjunction with Gregory's series, the Taylor series expansion for arctangent:
Derivation
The angle addition formula for arctangent asserts that
if
All of the Machin-like formulas can be derived by repeated application of equation . As an example, we show the derivation of Machin's original formula one has:
and consequently
Therefore also
and so finally
An insightful way to visualize equation is to picture what happens when two complex numbers are multiplied together:
The angle associated with a complex number is given by:
Thus, in equation , the angle associated with the product is:
Note that this is the same expression as occurs in equation . Thus equation can be interpreted as saying that multiplying two complex numbers means adding their associated angles (see multiplication of complex numbers).
The expression:
is the angle associated with:
Equation can be re-written as:
Here is an arbitrary constant that accounts for the difference in magnitude between the vectors on the two sides of the equation. The magnitudes can be ignored, only the angles are significant.
Using complex numbers
Other formulas may be generated using complex numbers. For example, the angle of a complex number is given by and, when one multiplies complex numbers, one adds their angles. If then is 45 degrees or radians. This means that if the real part and complex part are equal then the arctangent will equal . Since the arctangent of one has a very slow convergence rate if we find two complex numbers that when multiplied will
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https://en.wikipedia.org/wiki/Software%20craftsmanship
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Software craftsmanship is an approach to software development that emphasizes the coding skills of the software developers. It is a response by software developers to the perceived ills of the mainstream software industry, including the prioritization of financial concerns over developer accountability.
Historically, programmers have been encouraged to see themselves as practitioners of the well-defined statistical analysis and mathematical rigor of a scientific approach with computational theory. This has changed to an engineering approach with connotations of precision, predictability, measurement, risk mitigation, and professionalism. Practice of engineering led to calls for licensing, certification and codified bodies of knowledge as mechanisms for spreading engineering knowledge and maturing the field.
The Agile Manifesto, with its emphasis on "individuals and interactions over processes and tools" questioned some of these assumptions. The Software Craftsmanship Manifesto extends and challenges further the assumptions of the Agile Manifesto, drawing a metaphor between modern software development and the apprenticeship model of medieval Europe.
Overview
The movement traces its roots to the ideas expressed in written works. The Pragmatic Programmer by Andy Hunt and Dave Thomas and Software Craftsmanship by Pete McBreen explicitly position software development as heir to the guild traditions of medieval Europe. The philosopher Richard Sennett wrote about software as a modern craft in his book The Craftsman. Freeman Dyson, in his essay "Science as a Craft Industry", expands software crafts to include mastery of using software as a driver for economic benefit:
"In spite of the rise of Microsoft and other giant producers, software remains in large part a craft industry. Because of the enormous variety of specialized applications, there will always be room for individuals to write software based on their unique knowledge. There will always be niche markets to keep
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https://en.wikipedia.org/wiki/Deconstruction%20%28building%29
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In the context of physical construction, deconstruction is the selective dismantlement of building components, specifically for reuse, repurposing, recycling, and waste management. It differs from demolition where a site is cleared of its building by the most expedient means. Deconstruction has also been defined as "construction in reverse". Deconstruction requires a substantially higher degree of hands-on labor than does traditional demolition, but as such provides a viable platform for unskilled or unemployed workers to receive job skills training. The process of dismantling structures is an ancient activity that has been revived by the growing fields of sustainable and green building.
When buildings reach the end of their useful life, they are typically demolished and hauled to landfills. Building implosions or ‘wrecking-ball’ style demolitions are relatively inexpensive and offer a quick method of clearing sites for new structures. On the other hand, these methods create substantial amounts of waste. Components within old buildings may still be valuable, sometimes more valuable than at the time the building was constructed. Deconstruction is a method of harvesting what is commonly considered “waste” and reclaiming it into useful building material. Most modern buildings are difficult to perform deconstruction due to the designs of such buildings.
Contribution to sustainability
Deconstruction has strong ties to environmental sustainability. In addition to giving materials a new life cycle, deconstructing buildings helps to lower the need for virgin resources. This in turn leads to energy and emissions reductions from the refining and manufacture of new materials, especially when considering that an estimated 40% of global material flows can be attributed to construction, maintenance, and renovation of structures. As deconstruction is often done on a local level, many times on-site, energy and emissions are also saved in the transportation of materials. Deconst
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https://en.wikipedia.org/wiki/Dudeney%20number
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In number theory, a Dudeney number in a given number base is a natural number equal to the perfect cube of another natural number such that the digit sum of the first natural number is equal to the second. The name derives from Henry Dudeney, who noted the existence of these numbers in one of his puzzles, Root Extraction, where a professor in retirement at Colney Hatch postulates this as a general method for root extraction.
Mathematical definition
Let be a natural number. We define the Dudeney function for base and power to be the following:
where is the times the number of digits in the number in base .
A natural number is a Dudeney root if it is a fixed point for , which occurs if . The natural number is a generalised Dudeney number, and for , the numbers are known as Dudeney numbers. and are trivial Dudeney numbers for all and , all other trivial Dudeney numbers are nontrivial trivial Dudeney numbers.
For and , there are exactly six such integers :
A natural number is a sociable Dudeney root if it is a periodic point for , where for a positive integer , and forms a cycle of period . A Dudeney root is a sociable Dudeney root with , and a amicable Dudeney root is a sociable Dudeney root with . Sociable Dudeney numbers and amicable Dudeney numbers are the powers of their respective roots.
The number of iterations needed for to reach a fixed point is the Dudeney function's persistence of , and undefined if it never reaches a fixed point.
It can be shown that given a number base and power , the maximum Dudeney root has to satisfy this bound:
implying a finite number of Dudeney roots and Dudeney numbers for each order and base .
is the digit sum. The only Dudeney numbers are the single-digit numbers in base , and there are no periodic points with prime period greater than 1.
Dudeney numbers, roots, and cycles of Fp,b for specific p and b
All numbers are represented in base .
Extension to negative integers
Dudeney numbers can b
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https://en.wikipedia.org/wiki/Bucket-wheel%20excavator
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A bucket-wheel excavator (BWE) is a large heavy equipment machine used in surface mining.
Their primary function is that of a continuous digging machine in large-scale open-pit mining operations, removing thousands of tons of overburden a day. What sets them apart from other large-scale mining equipment, such as bucket chain excavators, is their use of a large wheel consisting of a continuous pattern of buckets which scoop material as the wheel turns. They are among the largest land or sea vehicles ever produced. The 14,200-ton Bagger 293 holds the Guinness World Record for the heaviest land-based vehicle ever built.
History
Bucket-wheel excavators have been used in mining for the past century, with some of the first being manufactured in the 1920s. They are used in conjunction with many other pieces of mining machinery (conveyor belts, spreaders, crushing stations, heap-leach systems, etc.) to move and mine massive amounts of overburden (waste). While the overall concepts that go into a BWE have not changed much, their size has grown drastically since the end of World War II.
In the 1950s two German mining firms ordered the world's first extremely large BWEs, and had three BWEs built for mining lignite near Cologne, Germany. The German BWEs had a wheel of over in diameter, weighed and were over long, with eighteen crawler units for movement and could cut a swath of over at one time
BWEs built since the 1990s, such as the Bagger 293, have reached sizes as large as tall, long, and as heavy as . The bucket-wheel itself can be over in diameter with as many as 20 buckets, each of which can hold over of material. BWEs have also advanced with respect to the extreme conditions in which they are now capable of operating. Many BWEs have been designed to operate in climates with temperatures as low as . Developers are now moving their focus toward automation and the use of electrical power.
Structure
A bucket wheel excavator (BWE) consists of a superstructure t
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https://en.wikipedia.org/wiki/Cray-4
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The Cray-4 was intended to be Cray Computer Corporation's successor to the failed Cray-3 supercomputer. It was marketed to compete with the T90 from Cray Research. CCC went bankrupt in 1995 before any Cray-4 had been delivered.
Design
The earlier Cray-3 was the first major application of gallium arsenide (GaAs) semiconductors in computing. It was not considered a success, and only one Cray-3 was delivered. Seymour Cray moved on to the Cray-4 design, announcing the design in 1994.
The Cray-4 was essentially a shrunk and sped-up version of the Cray-3, consisting of a number of vector processors attached to a fast memory. The Cray-3 supported from four to sixteen processors running at 474 MHz, while the Cray-4 scaled from four to sixty-four processors running at 1 GHz. The final packaging for the Cray-4 was intended to fit into , and was to be tested in the smaller one-CPU "tanks" from the Cray-3. A midrange system included 16 processors, 1,024 megawords (8192 MB) of memory and provided 32 gigaflops for $11 million.
The local memory architecture used on the Cray-2 and Cray-3 was dropped, returning to the mass of B- and T- registers on earlier designs, owing to Seymour's lack of success using the local memory effectively.
1994
"Significant technical progress was made during 1994 on the CRAY-4, which takes advantage of technologies and manufacturing processes developed during the design and manufacture of the CRAY-3. The Company announced introduction of the CRAY-4 to the market on November 10, 1994. Several single processor CRAY-4 prototype systems, each with 64 megawords of memory, were undergoing diagnostic testing prior to the Company filing for bankruptcy. The Company began testing individual CRAY-4 modules at the start of 1994 and planned to be able to deliver a 4-processor CRAY-4 prototype system by approximately the end of the second quarter of 1995. Upon filing of bankruptcy, the Company stopped work on the CRAY-4."
Legacy
The processor with serial number 0
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https://en.wikipedia.org/wiki/Input/output%20Buffer%20Information%20Specification
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Input/output Buffer Information Specification (IBIS) is a specification of a method for integrated circuit vendors to provide information about the input/output buffers of their product to their prospective customers without revealing the intellectual property of their implementation and without requiring proprietary encryption keys. From version 5.0, specification contains two separate types of models, "traditional IBIS" and "IBIS-AMI." The traditional model is generated in text format and consists of a number of tables that captures current vs. voltage (IV) and voltage vs. time (Vt) characteristics of the buffer, as well as the values of certain parasitic components. It is a standard data exchange format for exchanging modeling information among semiconductor device suppliers, simulation software suppliers, and end users.
Traditional IBIS models are generally used instead of SPICE models to perform various board level signal integrity (SI) simulations and timing analyses. IBIS models could be used to verify signal integrity requirements, especially for high-speed products.
IBIS-AMI models run in a special-purpose SerDes channel simulator, not in a SPICE-like simulator, and consist of two text files (*.ibs and *.ami) plus a platform-specific machine code executable file (*.dll on Windows, *.so on Linux). IBIS-AMI support statistical and so-called time-domain channel simulations, and three types of IC model ("impulse-only," "GetWave-only," and "dual mode")
History
Intel initiated IBIS in the early 1990s. Intel needed to have all of its divisions to present a common standardized model format to its external customers. This prompted Intel to solicit EDA vendors to participate in the development of a common model format. The first IBIS model, version 1.0, was aimed at describing CMOS circuits and TTL I/O buffers.
As IBIS evolved with the participation of more companies and industry members, an IBIS Open Forum was created to promote the application of IBIS as a s
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https://en.wikipedia.org/wiki/Alternative%20frequency
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Alternative frequency (or AF) is an option that allows a receiver to re-tune to a different frequency that provides the same station, when the first signal becomes too weak (e.g. when moving out of range). This is often used in car stereo systems, enabled by Radio Data System (RDS), or the U.S.-based Radio Broadcast Data System (RBDS).
Radio technology
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https://en.wikipedia.org/wiki/Ethyl%20acetoacetate
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The organic compound ethyl acetoacetate (EAA) is the ethyl ester of acetoacetic acid. It is a colorless liquid. It is widely used as a chemical intermediate in the production of a wide variety of compounds. It is used as a flavoring for food.
Preparation
Ethyl acetoacetate is produced industrially by treatment of diketene with ethanol.
The preparation of ethyl acetoacetate is a classic laboratory procedure. It is prepared via the Claisen condensation of ethyl acetate. Two moles of ethyl acetate condense to form one mole each of ethyl acetoacetate and ethanol.
Reactivity
Acidity
Ethyl acetoacetate is diprotic:
CH3C(O)CH2CO2Et + NaH → CH3C(O)CH(Na)CO2Et + H2
CH3C(O)CH(Na)CO2Et + BuLi → LiCH2C(O)CH(Na)CO2Et + BuH
Keto-enol tautomerism
Ethyl acetoacetate is subject to keto-enol tautomerism. In the neat liquid at 33 °C, the enol consists of 15% of the total.
Multicarbon building block
Ethyl acetoacetic acid is a building block in organic synthesis since the protons alpha to carbonyl groups are acidic, and the resulting carbanion undergoes nucleophilic substitution. Ethyl acetoacetate is often used in the acetoacetic ester synthesis similar to diethyl malonate in the malonic ester synthesis or the Knoevenagel condensation. A subsequent thermal decarboxylation is also possible.
The dianion of ethylacetoacetate is also a useful building block, except that the electrophile adds to the terminal carbon. The strategy can be depicted in the following simplified form:
LiCH2C(O)CH(Na)CO2Et + RX → RCH2C(O)CH(Na)CO2Et + LiX
Ligand
Similar to the behavior of acetylacetone, the enolate of ethyl acetoacetate can also serve as a bidentate ligand. For example, it forms purple coordination complexes with iron(III) salts:
Reduction
Reduction of ethyl acetoacetate gives ethyl 3-hydroxybutyrate.
Transesterification
Ethyl acetoacetate transesterifies to give benzyl acetoacetate via a mechanism involving acetylketene. Ethyl (and other) acetoacetates nitrosate readily with equimolar
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https://en.wikipedia.org/wiki/Systems%20management
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Systems management refers to enterprise-wide administration of distributed systems including (and commonly in practice) computer systems. Systems management is strongly influenced by network management initiatives in telecommunications. The application performance management (APM) technologies are now a subset of Systems management. Maximum productivity can be achieved more efficiently through event correlation, system automation and predictive analysis which is now all part of APM.
Centralized management has a time and effort trade-off that is related to the size of the company, the expertise of the IT staff, and the amount of technology being used:
For a small business startup with ten computers, automated centralized processes may take more time to learn how to use and implement than just doing the management work manually on each computer.
A very large business with thousands of similar employee computers may clearly be able to save time and money, by having IT staff learn to do systems management automation.
A small branch office of a large corporation may have access to a central IT staff, with the experience to set up automated management of the systems in the branch office, without need for local staff in the branch office to do the work.
Systems management may involve one or more of the following tasks:
Hardware inventories.
Server availability monitoring and metrics.
Software inventory and installation.
Anti-virus and anti-malware.
User's activities monitoring.
Capacity monitoring.
Security management.
Storage management.
Network capacity and utilization monitoring.
Anti-manipulation management
Functions
Functional groups are provided according to International Telecommunication Union Telecommunication Standardization Sector (ITU-T) Common management information protocol (X.700) standard. This framework is also known as Fault, Configuration, Accounting, Performance, Security (FCAPS).
Fault management
Troubleshooting, error logging an
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https://en.wikipedia.org/wiki/Multivector
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In multilinear algebra, a multivector, sometimes called Clifford number or multor, is an element of the exterior algebra of a vector space . This algebra is graded, associative and alternating, and consists of linear combinations of simple -vectors (also known as decomposable -vectors or -blades) of the form
where are in .
A -vector is such a linear combination that is homogeneous of degree (all terms are -blades for the same ). Depending on the authors, a "multivector" may be either a -vector or any element of the exterior algebra (any linear combination of -blades with potentially differing values of ).
In differential geometry, a -vector is a vector in the exterior algebra of the tangent vector space; that is, it is an antisymmetric tensor obtained by taking linear combinations of the exterior product of tangent vectors, for some integer . A differential -form is a -vector in the exterior algebra of the dual of the tangent space, which is also the dual of the exterior algebra of the tangent space.
For and , -vectors are often called respectively scalars, vectors, bivectors and trivectors; they are respectively dual to 0-forms, 1-forms, 2-forms and 3-forms.
Exterior product
The exterior product (also called the wedge product) used to construct multivectors is multilinear (linear in each input), associative and alternating. This means for vectors u, v and w in a vector space V and for scalars α, β, the exterior product has the properties:
Linear in an input:
Associative:
Alternating:
The exterior product of k vectors or a sum of such products (for a single k) is called a grade k multivector, or a k-vector. The maximum grade of a multivector is the dimension of the vector space V.
Linearity in either input together with the alternating property implies linearity in the other input. The multilinearity of the exterior product allows a multivector to be expressed as a linear combination of exterior products of basis vectors of V. The exterior
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https://en.wikipedia.org/wiki/IGB%20Eletr%C3%B4nica
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IGB Eletrônica S.A. (Portuguese for IGB Electronics), doing business as Gradiente, is a Brazilian consumer electronics company based in Manaus, and with offices in São Paulo. The company designs and markets many product lines, including video (e.g. televisions, DVD players), audio, home theater, high end acoustics, office and mobile stereo, wireless, mobile/smart phones, and tablets for the Brazilian market.
History
The company was founded in 1964. In 1993 they founded Playtronic, a fully owned subsidiary who licensed the manufacturing of Nintendo consoles in Brazil, and while publishing games for various systems they also provided Portuguese translations of some games (among them, South Park and Shadow Man for the Nintendo 64). However, they stopped the partnership with Nintendo in 2003 because of the high price of the dollar at the time.
In 1997, Gradiente established a joint venture with Finland-based telecommunications manufacturing firm Nokia, where they were granted the license to manufacture variants of Nokia mobile phones locally under the Nokia and Gradiente brand names.
The Gradiente iPhone case
In 2000, Gradiente, now legally known as IGB Eletrônica SA, filed for the brand name "iphone" in Brazil's INPI (National Institute of Industrial Property, the trademark authority). Only by 2008 the Brazilian government granted full brand ownership for Gradiente, and currently (since January 2012), the company is selling Android-based smartphones under this name. Until 2008 that trademark is fully owned by IGB Eletrônica SA, which released its Android-powered iphone neo one under the Gradiente brand. The iphone neo one is sold for R$ 599 (about US$287), a dual-SIM handset running Android 2.3.4 Gingerbread. It has a 3.7-inch, 320 x 480 display, a 700 MHz CPU, 2GB of expandable storage, Bluetooth, 3G, WiFi and 5 / 0.3-megapixel camera.
See also
List of phonograph manufacturers
Gradiente Expert
References
External links
Audio equipment manufacturers of Br
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https://en.wikipedia.org/wiki/CLOVER2000
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CLOVER is the name of a series or class of modem modulation techniques (“waveforms”) specifically designed for use over high frequency (HF) radio systems.
CLOVER-II was the first CLOVER waveform sold commercially, developed by Ray Petit, W7GHM, and HAL Communications in 1990–92.
CLOVER-2000 is a higher-rate and wider bandwidth version of CLOVER developed in 1995.
CLOVER-400 is a special 400 Hz wide waveform that was developed for Globe Wireless.
Modulation schemes
In ARQ mode, all CCB's (CLOVER Control Blocks) use BPSK modulation and data blocks may be sent using BPSK, QPSK, 8PSK (see phase-shift keying), 8P2A, or 16P4A (see QAM) modulation. Data is sent in 255-byte blocks. The FEC broadcast mode of CLOVER-2000 is usually disabled although special formats are available for specific applications.
The coding polynomial protocol could be shared after payment in Bit Coin
Radio Interface requirements for CLOVER-2000
The CLOVER waveform offers high performance, error correction, and spectral efficiency. CLOVER is specifically designed for use over HF radio communications links. It may be used with virtually any modern HF SSB radio. However, certain special set-up and adjustment techniques are required to get maximum performance when using CLOVER.
See also
Shortwave
Radioteletype
PSK31
PACTOR
SITOR
References
External links
Signal Identification Wiki CLOVER 2000
ARRL.org CLOVER 2000
Quantized radio modulation modes
Packet radio
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https://en.wikipedia.org/wiki/PSK63
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PSK63 (meaning Phase Shift Keying at a rate of 63 baud) is a digital radio modulation mode used primarily in the amateur radio field to conduct real-time keyboard-to-keyboard informal text chat between amateur radio operators.
History
In April 2003, Skip Teller, KH6TY, the creator of Digipan, requested an addition to Moe (AE4JY) Wheatley's PSKCore DLL to support the PSK63 mode. Subsequently, another mode - PSK125 - has been added to the PSKCore DLL.
Unlike PSK63F, PSK63 does not use forward error correction (FEC).
PSK 63 is twice as fast as PSK63F's but exactly the same speed as PSK125F.
Mode Support
PSK63 is now supported directly in KH6TY's own QuikPSK software, as well as in Digipan, AA6YQ's WinWarbler, F6CTE's MultiPSK, AE4JY's WinPSK, HB9DRV's DM780, PSK31 Deluxe, MMVARI, Fldigi, MIXW, and DL4RCK's RCKRtty. It is also supported in hardware by the Elecraft KX3.
Others are likely to follow, now that version 1.17 of the PSKCore dll supports both PSK31 and PSK63. QuikPSK, MultiPSK and PSK31 Deluxe can decode up to 24 signals simultaneously. QuickPSK has a unique additional capability to send colour thumbnail pictures (32x32 pixel, 16 colours) using the PSK63 mode.
PSK Software Core
A PSK63-only version of the PSKCore dll is also available at KH6TY's web site for use with any software that uses PSKCore to implement PSK31. Simply by replacing the original PSKCore file (it is suggested that you rename the original rather than deleting it) with the new version, the PSK31 software supports PSK63 instead of PSK31.
This technique has been used during early experiments with the PSK63 mode, but it is not likely to continue to be very widely used now that software that supports PSK63 directly has become widely available.
The official distribution of the PSKCore DLL, which supports PSK31, PSK63, and PSK125, is available on Moe (AE4JY) Wheatley's website.
See also
PSK31
MT63
Varicode
Radioteletype
Shortwave
References
External links
"BPSK63, QPSK63 and PS
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https://en.wikipedia.org/wiki/Tensor%20product%20of%20Hilbert%20spaces
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In mathematics, and in particular functional analysis, the tensor product of Hilbert spaces is a way to extend the tensor product construction so that the result of taking a tensor product of two Hilbert spaces is another Hilbert space. Roughly speaking, the tensor product is the metric space completion of the ordinary tensor product. This is an example of a topological tensor product. The tensor product allows Hilbert spaces to be collected into a symmetric monoidal category.
Definition
Since Hilbert spaces have inner products, one would like to introduce an inner product, and therefore a topology, on the tensor product that arises naturally from those of the factors. Let and be two Hilbert spaces with inner products and respectively. Construct the tensor product of and as vector spaces as explained in the article on tensor products. We can turn this vector space tensor product into an inner product space by defining
and extending by linearity. That this inner product is the natural one is justified by the identification of scalar-valued bilinear maps on and linear functionals on their vector space tensor product. Finally, take the completion under this inner product. The resulting Hilbert space is the tensor product of and
Explicit construction
The tensor product can also be defined without appealing to the metric space completion. If and are two Hilbert spaces, one associates to every simple tensor product the rank one operator from to that maps a given as
This extends to a linear identification between and the space of finite rank operators from to The finite rank operators are embedded in the Hilbert space of Hilbert–Schmidt operators from to The scalar product in is given by
where is an arbitrary orthonormal basis of
Under the preceding identification, one can define the Hilbertian tensor product of and that is isometrically and linearly isomorphic to
Universal property
The Hilbert tensor product is characterized by the foll
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https://en.wikipedia.org/wiki/PACTOR
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PACTOR is a radio modulation mode used by amateur radio operators, marine radio stations, military or government users such as the US Department of Homeland Security, and radio stations in isolated areas to send and receive digital information via radio.
PACTOR is an evolution of both AMTOR and packet radio; its name is a portmanteau of these two technologies' names.
PACTOR uses a combination of simple FSK modulation, and the ARQ protocol for robust error detection and data throughput. Generational improvements to PACTOR include PACTOR II, PACTOR III, and PACTOR IV which are capable of higher speed transmission. PACTOR is most commonly used on frequencies between 1 MHz and 30 MHz.
History
PACTOR (Latin: The mediator) was developed by Special Communications Systems GmbH (SCS) and released to the public in 1991.
PACTOR was developed in order to improve the reception of digital data when the received signal was weak or noisy. It combines the bandwidth efficiency of packet radio with the error-correction (CRC) and automatic repeat request (ARQ) of AMTOR. Amateur radio operators were instrumental in developing and implementing these digital modes.
Current uses
PACTOR radio equipment consists of an HF transceiver, a computer and a terminal node controller. Software running on the computer drives the terminal node controller. The most commonly used amateur program for this purpose is Airmail.
PACTOR is used by Amateur Bulletin board system operators to exchange public messages, and open conversations across the world. It is also used by the NTSD (digital) portion of the ARRL's National Traffic System (NTS) to pass digital ARRL Radiograms. Newer PACTOR modes are used to transfer large binary data files and Internet e-mail, particularly via the Winlink global e-mail system.
The SailMail network transfers e-mail on behalf of marine stations.
Technical characteristics
PACTOR is a set of standardized modes used by radio operators for FSK radioteletype transfer of d
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https://en.wikipedia.org/wiki/Guess%202/3%20of%20the%20average
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In game theory, "guess of the average" is a game that explores how a player’s strategic reasoning process takes into account the mental process of others in the game.
In this game, players simultaneously select a real number between 0 and 100, inclusive. The winner of the game is the player(s) who select a number closest to of the average of numbers chosen by all players.
History
Alain Ledoux is the founding father of the "guess of the average" game. In 1981, Ledoux used this game as a tie breaker in his French magazine Jeux et Stratégie. He asked about 4,000 readers, who reached the same number of points in previous puzzles, to state an integer between 1 and 1,000,000,000. The winner was the one who guessed closest to of the average guess. Rosemarie Nagel (1995) revealed the potential of guessing games of that kind: They are able to disclose participants' "depth of reasoning."
In his influential book, Keynes compared the determination of prices in a stock market to that of a beauty contest. The competitors had to pick out the six prettiest faces from 100 photos, and the winner is the competitor whose choices best matches the average preferences of all the competitors. Keynes observed that "It is not a case of choosing those that, to the best of one’s judgment, are really the prettiest, nor even those that average opinion genuinely thinks the prettiest. We have reached the third degree where we devote our intelligences to anticipating what average opinion expects the average opinion to be. And there are some, I believe, who practice the fourth, fifth and higher degrees."
Due to the analogy to Keynes's comparison of newspaper beauty contests and stock market investments the guessing game is also known as the Keynesian beauty contest. Rosemarie Nagel's experimental beauty contest became a famous game in experimental economics. The forgotten inventor of this game was unearthed in 2009 during an online beauty contest experiment with chess players provided by t
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https://en.wikipedia.org/wiki/Transparent%20Network%20Substrate
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Transparent Network Substrate (TNS), a proprietary Oracle computer-networking technology, supports homogeneous peer-to-peer connectivity on top of other networking technologies such as TCP/IP, SDP and named pipes. TNS operates mainly for connection to Oracle databases.
Protocol
TNS uses a proprietary protocol. Some details have, however, been reverse engineered.
See also
Transparency (computing)
Oracle Net Services
Protocol stack
References
External links
Oracle 8 Architecture and Concepts
Oracle 9i Architecture of Oracle Net Services
Oracle Corporation
Network protocols
Oracle software
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https://en.wikipedia.org/wiki/ABTS
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In biochemistry, ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) is a chemical compound used to observe the reaction kinetics of specific enzymes. A common use for it is in the enzyme-linked immunosorbent assay (ELISA) to detect the binding of molecules to each other.
It is commonly used as a substrate with hydrogen peroxide for a peroxidase enzyme (such as horseradish peroxidase) or alone with blue multicopper oxidase enzymes (such as laccase or bilirubin oxidase). Its use allows the reaction kinetics of peroxidases themselves to be followed. In this way it also can be used to indirectly follow the reaction kinetics of any hydrogen peroxide-producing enzyme, or to simply quantify the amount of hydrogen peroxide in a sample.
The formal reduction potentials for ABTS are high enough for it to act as an electron donor for the reduction of oxo species such as molecular oxygen and hydrogen peroxide, particularly at the less-extreme pH values encountered in biological catalysis. Under these conditions, the sulfonate groups are fully deprotonated and the mediator exists as a dianion.
ABTS–· + e– → ABTS2– E° = 0.67 V vs SHE
ABTS + e– → ABTS–· E° = 1.08 V vs SHE
This compound is chosen because the enzyme facilitates the reaction with hydrogen peroxide, turning it into a green and soluble end-product. Its new absorbance maximum of 420 nm light (ε = 3.6 × 104 M–1 cm–1) can easily be followed with a spectrophotometer, a common laboratory instrument.
It is sometimes used as part of a glucose estimating reagent when finding glucose concentrations of solutions such as blood serum.
ABTS is also frequently used by the food industry and agricultural researchers to measure the antioxidant capacities of foods. In this assay, ABTS is converted to its radical cation by addition of sodium persulfate. This radical cation is blue in color and absorbs light at 415, 645, 734 and 815 nm. The ABTS radical cation is reactive towards most antioxidants including phenolics, th
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https://en.wikipedia.org/wiki/Fenestra
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A fenestra (fenestration; : fenestrae or fenestrations) is any small opening or pore, commonly used as a term in the biological sciences. It is the Latin word for "window", and is used in various fields to describe a pore in an anatomical structure.
Biological morphology
In morphology, fenestrae are found in cancellous bones, particularly in the skull. In anatomy, the round window and oval window are also known as the fenestra rotunda and the fenestra ovalis. In microanatomy, fenestrae are found in endothelium of fenestrated capillaries, enabling the rapid exchange of molecules between the blood and surrounding tissue. The elastic layer of the tunica intima is a fenestrated membrane. In surgery, a fenestration is a new opening made in a part of the body to enable drainage or access.
Plant biology and mycology
In plant biology, the perforations in a perforate leaf are also described as fenestrae, and the leaf is called a fenestrate leaf. The leaf window is also known as a fenestra, and is a translucent structure that transmits light, as in Fenestraria.
Examples of fenestrate structures in the fungal kingdom include the symmetrically arranged gaps in the indusium ("skirt") of the mushroom Phallus duplicatus, and the thallus of the coral lichen Pulchrocladia retipora.
Zoology
In zoology, the trilobite Fenestraspis possessed extensive fenestrae in the posterior part of the body. In the paleognathae, there is an ilio–ischiatic fenestra.
Fenestrae are also used to distinguish the three types of amniote:
See also
Fenestron, a shrouded tail rotor of a helicopter
References
Anatomy
Biology
Angiology
Fungal morphology and anatomy
sv:Fenestrae
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https://en.wikipedia.org/wiki/Devil%27s%20garden
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In myrmecology and forest ecology, a devil's garden (Kichwa: Supay chakra) is a large stand of trees in the Amazon rainforest consisting of at most three tree species and the ant Myrmelachista schumanni. Devil's gardens can reach up to sizes of 600 trees and are inhabited by a single ant colony, containing up to 3 million workers and 15,000 queens. In a 2002 to 2004 census of the Amazon, devil's gardens were shown to have grown by 0.7 % per year. The relationship between tree and ant may persist for more than 800 years. A devil's garden is considered an example of mutualism, a type of symbiotic relationship between species.
Background
Devil's gardens were named because locals believed that an evil forest spirit Chullachaki (meaning "uneven foot, single foot" in Kichwa) or Chuyathaqi lived in them.
Types
Inhabited by the ant Myrmelachista schumanni, devil's gardens, in different regions of the Amazon, can be dominated by different tree species. In southeastern Peru, devil's gardens are dominated by Cordia nodosa (Boraginaceae) and occasionally mixed with Tococa occidentalis (Melastomataceae). At higher elevations, the tree species Tapirira guianensis (Anacardiaceae) can be found dominating gardens. In southeastern Ecuador and northeastern Peru the most common tree species found in devil's gardens are Duroia hirsuta (Rubiaceae).
Symbiosis
The mutualistic symbiosis between the ant Myrmelachista schumanni and the tree Duroia hirsuta begins when an ant queen colonizes an isolated tree. The ants make nesting sites in the hollow stems and leaves of the tree, called domatia. The ants eliminate competition for the tree by poisoning all plants, except the host tree, with formic acid. Because other plants are killed off, D. hirsuta saplings are able to grow and the ant colony is able to expand.
The tree provides shelter (hollow stems and domatia) and food (leaves) for the ants, and the ants provide a suitable environment for the trees to grow by eliminating competing p
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https://en.wikipedia.org/wiki/Unit%20propagation
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Unit propagation (UP) or Boolean Constraint propagation (BCP) or the one-literal rule (OLR) is a procedure of automated theorem proving that can simplify a set of (usually propositional) clauses.
Definition
The procedure is based on unit clauses, i.e. clauses that are composed of a single literal, in conjunctive normal form. Because each clause needs to be satisfied, we know that this literal must be true. If a set of clauses contains the unit clause , the other clauses are simplified by the application of the two following rules:
every clause (other than the unit clause itself) containing is removed (the clause is satisfied if is);
in every clause that contains this literal is deleted ( can not contribute to it being satisfied).
The application of these two rules lead to a new set of clauses that is equivalent to the old one.
For example, the following set of clauses can be simplified by unit propagation because it contains the unit clause .
Since contains the literal , this clause can be removed altogether. Since contains the negation of the literal in the unit clause, this literal can be removed from the clause. The unit clause is not removed; this would make the resulting set not equivalent to the original one; this clause can be removed if already stored in some other form (see section "Using a partial model"). The effect of unit propagation can be summarized as follows.
The resulting set of clauses is equivalent to the above one. The new unit clause that results from unit propagation can be used for a further application of unit propagation, which would transform into .
Unit propagation and resolution
The second rule of unit propagation can be seen as a restricted form of resolution, in which one of the two resolvents must always be a unit clause. As for resolution, unit propagation is a correct inference rule, in that it never produces a new clause that was not entailed by the old ones. The differences between unit propagation and re
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https://en.wikipedia.org/wiki/GeoGebra
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GeoGebra (a portmanteau of geometry and algebra) is an interactive geometry, algebra, statistics and calculus application, intended for learning and teaching mathematics and science from primary school to university level. GeoGebra is available on multiple platforms, with apps for desktops (Windows, macOS and Linux), tablets (Android, iPad and Windows) and web. It is presently owned by Indian edutech firm Byju's.
History
GeoGebra's creator, Markus Hohenwarter, started the project in 2001 as part of his master's thesis at the University of Salzburg. After a successful Kickstarter campaign, GeoGebra expanded its offering to include an iPad, an Android and a Windows Store app version. In 2013, GeoGebra incorporated Xcas into its CAS view. The project is now freeware (with open-source portions) and multi-lingual, and Hohenwarter continues to lead its development at the University of Linz.
GeoGebra includes both commercial and not-for-profit entities that work together from the head office in Linz, Austria, to expand the software and cloud services available to users.
In December 2021, GeoGebra was acquired by edtech conglomerate Byju's for approximately $100 million USD.
Features
GeoGebra is an interactive mathematics software suite for learning and teaching science, technology, engineering, and mathematics from primary school up to the university level. Constructions can be made with points, vectors, segments, lines, polygons, conic sections, inequalities, implicit polynomials and functions, all of which can be edited dynamically later. Elements can be entered and modified using mouse and touch controls, or through an input bar. GeoGebra can store variables for numbers, vectors and points, calculate derivatives and integrals of functions, and has a full complement of commands like Root or Extremum. Teachers and students can use GeoGebra as an aid in formulating and proving geometric conjectures.
GeoGebra's main features are:
Interactive geometry environment (2D
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https://en.wikipedia.org/wiki/Boolean-valued%20model
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In mathematical logic, a Boolean-valued model is a generalization of the ordinary Tarskian notion of structure from model theory. In a Boolean-valued model, the truth values of propositions are not limited to "true" and "false", but instead take values in some fixed complete Boolean algebra.
Boolean-valued models were introduced by Dana Scott, Robert M. Solovay, and Petr Vopěnka in the 1960s in order to help understand Paul Cohen's method of forcing. They are also related to Heyting algebra semantics in intuitionistic logic.
Definition
Fix a complete Boolean algebra B and a first-order language L; the signature of L will consist of a collection of constant symbols, function symbols, and relation symbols.
A Boolean-valued model for the language L consists of a universe M, which is a set of elements (or names), together with interpretations for the symbols. Specifically, the model must assign to each constant symbol of L an element of M, and to each n-ary function symbol f of L and each n-tuple of elements of M, the model must assign an element of M to the term f(a0,...,an-1).
Interpretation of the atomic formulas of L is more complicated. To each pair a and b of elements of M, the model must assign a truth value to the expression ; this truth value is taken from the Boolean algebra B. Similarly, for each n-ary relation symbol R of L and each n-tuple of elements of M, the model must assign an element of B to be the truth value .
Interpretation of other formulas and sentences
The truth values of the atomic formulas can be used to reconstruct the truth values of more complicated formulas, using the structure of the Boolean algebra. For propositional connectives, this is easy; one simply applies the corresponding Boolean operators to the truth values of the subformulae. For example, if φ(x) and ψ(y,z) are formulas with one and two free variables, respectively, and if a, b, c are elements of the model's universe to be substituted for x, y, and z, then the truth va
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https://en.wikipedia.org/wiki/Davis%E2%80%93Putnam%20algorithm
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The Davis–Putnam algorithm was developed by Martin Davis and Hilary Putnam for checking the validity of a first-order logic formula using a resolution-based decision procedure for propositional logic. Since the set of valid first-order formulas is recursively enumerable but not recursive, there exists no general algorithm to solve this problem. Therefore, the Davis–Putnam algorithm only terminates on valid formulas. Today, the term "Davis–Putnam algorithm" is often used synonymously with the resolution-based propositional decision procedure (Davis–Putnam procedure) that is actually only one of the steps of the original algorithm.
Overview
The procedure is based on Herbrand's theorem, which implies that an unsatisfiable formula has an unsatisfiable ground instance, and on the fact that a formula is valid if and only if its negation is unsatisfiable. Taken together, these facts imply that to prove the validity of φ it is enough to prove that a ground instance of ¬φ is unsatisfiable. If φ is not valid, then the search for an unsatisfiable ground instance will not terminate.
The procedure for checking validity of a formula φ roughly consists of these three parts:
put the formula ¬φ in prenex form and eliminate quantifiers
generate all propositional ground instances, one by one
check if each instance is satisfiable.
If some instance is unsatisfiable, then return that φ is valid. Else continue checking.
The last part is a SAT solver based on resolution (as seen on the illustration), with an eager use of unit propagation and pure literal elimination (elimination of clauses with variables that occur only positively or only negatively in the formula).
Input: A set of clauses Φ.
Output: A Truth Value: true if Φ can be satisfied, false otherwise.
function DP-SAT(Φ)
repeat
// unit propagation:
while Φ contains a unit clause {l} do
for every clause c in Φ that contains l do
Φ ← remove-from-formula(c, Φ);
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https://en.wikipedia.org/wiki/Initiative%20for%20Open%20Authentication
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Initiative for Open Authentication (OATH) is an industry-wide collaboration to develop an open reference architecture using open standards to promote the adoption of strong authentication. It has close to thirty coordinating and contributing members and is proposing standards for a variety of authentication technologies, with the aim of lowering costs and simplifying their functions.
Terminology
The name OATH is an acronym from the phrase "open authentication", and is pronounced as the English word "oath".
OATH is not related to OAuth, an open standard for authorization.
See also
HOTP: An HMAC-Based One-Time Password Algorithm (RFC 4226)
TOTP: Time-Based One-Time Password Algorithm (RFC 6238)
OCRA: OATH Challenge-Response Algorithm (RFC 6287)
Portable Symmetric Key Container (PSKC) (RFC 6030)
Dynamic Symmetric Key Provisioning Protocol (DSKPP) (RFC 6063)
FIDO Alliance
References
External links
List of OATH members
OATH Specifications
Computer security organizations
Computer access control
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https://en.wikipedia.org/wiki/Zimbra
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Zimbra Collaboration, formerly known as the Zimbra Collaboration Suite (ZCS) before 2019, is a collaborative software suite that includes an email server and a web client.
Zimbra was initially developed by LiquidSys, which changed their name to Zimbra, Inc. on 26 July 2005. The Zimbra Collaboration Suite was first released in 2005. The company was subsequently purchased by Yahoo! on September 17, 2007, and later sold to VMware on January 12, 2010. In July 2013, it was sold by VMware to Telligent Systems which changed its name to Zimbra, Inc. in September 2013. It was then acquired by Synacor on 18 August 2015.
According to former Zimbra President and CTO Scott Dietzen, the name for Zimbra is derived from the song "I Zimbra" by Talking Heads.
Edition
The software consists of both client and server components, and at one time also offered a desktop email client, called Zimbra Desktop. Two versions of Zimbra are available: an open-source version, and a commercially supported version ("Network Edition") with closed-source components such as a proprietary Messaging Application Programming Interface connector to Outlook for calendar and contact synchronization.
The now discontinued Zimbra Desktop was a full-featured free desktop email client. Development was discontinued under VMware's stewardship in 2013 but was restarted in February 2014, but was ended again by 2019. The web client featured an HTML5 offline mode starting with version 8.5.
The Zimbra Web Client is a full-featured collaboration suite that supports email and group calendars. At one time it featured document-sharing using an Ajax web interface that enabled tool tips, drag-and-drop items, and right-click menus in the UI. Today it has document sharing, chat, and videoconferencing. Also included are advanced searching capabilities and date relations, online document authoring, "Zimlet" mashups, and a full administration UI. It is written using the Zimbra Ajax Toolkit.
The Zimbra Server uses several open
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https://en.wikipedia.org/wiki/Cantor%27s%20paradox
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In set theory, Cantor's paradox states that there is no set of all cardinalities. This is derived from the theorem that there is no greatest cardinal number. In informal terms, the paradox is that the collection of all possible "infinite sizes" is not only infinite, but so infinitely large that its own infinite size cannot be any of the infinite sizes in the collection. The difficulty is handled in axiomatic set theory by declaring that this collection is not a set but a proper class; in von Neumann–Bernays–Gödel set theory it follows from this and the axiom of limitation of size that this proper class must be in bijection with the class of all sets. Thus, not only are there infinitely many infinities, but this infinity is larger than any of the infinities it enumerates.
This paradox is named for Georg Cantor, who is often credited with first identifying it in 1899 (or between 1895 and 1897). Like a number of "paradoxes" it is not actually contradictory but merely indicative of a mistaken intuition, in this case about the nature of infinity and the notion of a set. Put another way, it is paradoxical within the confines of naïve set theory and therefore demonstrates that a careless axiomatization of this theory is inconsistent.
Statements and proofs
In order to state the paradox it is necessary to understand that the cardinal numbers are totally ordered, so that one can speak about one being greater or less than another. Then Cantor's paradox is:
This fact is a direct consequence of Cantor's theorem on the cardinality of the power set of a set.
Another consequence of Cantor's theorem is that the cardinal numbers constitute a proper class. That is, they cannot all be collected together as elements of a single set. Here is a somewhat more general result.
Discussion and consequences
Since the cardinal numbers are well-ordered by indexing with the ordinal numbers (see Cardinal number, formal definition), this also establishes that there is no greatest ordinal number
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https://en.wikipedia.org/wiki/S%C3%B8rensen%20formol%20titration
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The Sørensen formol titration(SFT) invented by S. P. L. Sørensen in 1907 is a titration of an amino acid with potassium hydroxide in the presence of formaldehyde. It is used in the determination of protein content in samples.
If instead of an amino acid an ammonium salt is used the reaction product with formaldehyde is hexamethylenetetramine:
The liberated hydrochloric acid is then titrated with the base and the amount of ammonium salt used can be determined.
With an amino acid the formaldehyde reacts with the amino group to form a methylene amino (R-N=CH2) group. The remaining acidic carboxylic acid group can then again be titrated with base.
In winemaking
Formol titration is one of the methods used in winemaking to measure yeast assimilable nitrogen needed by wine yeast in order to successfully complete fermentation.
Accuracy in formol titration
There has been some inaccuracies of the SFT caused by the differences in the basicity of the nitrogen in different amino acids which were explained by S. L. Jodidi. For instances, proline(an amino acid), histidine, and lysine yields too low values compared to the theory. Unlike alpha, monobasic (containing one amino group per molecule) amino acids, these amino (or imino) acids' nitrogens have inconstant basicity, which results in partial reaction with formaldehyde.
In case of tyrosine, the actual results are too high due to the negative hydroxyl group (-OH), which acts as a base. This explanation is supported by the fact that phenylalanine can be accurately titrated.
References
Biochemistry methods
Titration
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https://en.wikipedia.org/wiki/CGMS-A
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Copy Generation Management System – Analog (CGMS-A) is a copy protection mechanism for analog television signals. It consists of a waveform inserted into the non-picture vertical blanking interval (VBI) of an analogue video signal. If a compatible recording device (for example, a DVD recorder) detects this waveform, it may block or restrict recording of the video content.
It is not the same as the broadcast flag, which is designed for use in digital television signals, although the concept is the same. There is a digital form of CGMS specified as CGMS-D which is required by the DTCP ("5C") protection standard.
History
CGMS-A has been in existence since 1995, and has been standardized by various organizations including the IEC and EIA/CEA. It is used in devices such as PVRs/DVRs, DVD players and recorders, D-VHS, and Blu-ray recorders, as well certain television broadcasts. More recent TiVo firmware releases comply with CGMS-A signals.
Applications
Implementation of CGMS-A is required for certain applications by DVD CCA license. D-VHS and some DVD recorders comply with CGMS-A signal on analog inputs. The technology requires minimal signal processing.
Where the source signal is analogue (e.g. VHS, analogue broadcast), the CGMS-A signalling may be present in that source.
Where the source signal is digital (e.g. DVD, digital broadcast), then the Copy Control Information (CCI) is carried in metadata in the digital transport or program stream, and a compliant hardware device (e.g. a DVD player) will read that data, and encode it into the analogue video signal generated within the device itself.
There is no blanket legal requirement for devices which record video to detect or act upon the CGMS-A information. For example, the DMCA "does not require manufacturers of consumer electronics, telecommunications or computing equipment to design their products affirmatively to respond to any particular technological measure.".
Standardization
CGMS-A is standardized throug
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https://en.wikipedia.org/wiki/Polytomy
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An internal node of a phylogenetic tree is described as a polytomy or multifurcation if (i) it is in a rooted tree and is linked to three or more child subtrees or (ii) it is in an unrooted tree and is attached to four or more branches. A tree that contains any multifurcations can be described as a multifurcating tree.
Soft polytomies vs. hard polytomies
Two types of polytomies are recognised, soft and hard polytomies.
Soft polytomies are the result of insufficient phylogenetic information: though the lineages diverged at different times – meaning that some of these lineages are closer relatives than others, and the available data does not allow recognition of this. Most polytomies are soft, meaning that they would be resolved into a typical tree of dichotomies if better data were available.
In contrast, a hard polytomy represents a true divergence event of three or more lineages.
Applications
Interpretations for a polytomy depend on the individuals, that are represented in the phylogenetic tree.
Species polytomies
If the lineages in the phylogenetic tree stand for species, a polytomy shows the simultaneous speciation of three or more species. In particular situations they may be common, for example when a species that has rapidly expanded its range or is highly panmictic undergoes peripatric speciation in different regions.
An example is the Drosophila simulans species complex. Here, the ancestor seems to have colonized two islands at the same time but independently, yielding two equally old but divergently evolved daughter species
Molecular polytomies
If a phylogenetic tree is reconstructed from DNA sequence data of a particular gene, a hard polytomy arises when three or more sampled genes trace their ancestry to a single gene in an ancestral organism. In contrast, a soft polytomy stems from branches on gene trees of finite temporal duration but for which no substitutions have occurred.
Recognizing hard polytomies
As DNA sequence evolution is usua
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https://en.wikipedia.org/wiki/Boole%27s%20expansion%20theorem
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Boole's expansion theorem, often referred to as the Shannon expansion or decomposition, is the identity: , where is any Boolean function, is a variable, is the complement of , and and are with the argument set equal to and to respectively.
The terms and are sometimes called the positive and negative Shannon cofactors, respectively, of with respect to . These are functions, computed by restrict operator, and (see valuation (logic) and partial application).
It has been called the "fundamental theorem of Boolean algebra". Besides its theoretical importance, it paved the way for binary decision diagrams (BDDs), satisfiability solvers, and many other techniques relevant to computer engineering and formal verification of digital circuits.
In such engineering contexts (especially in BDDs), the expansion is interpreted as a if-then-else, with the variable being the condition and the cofactors being the branches ( when is true and respectively when is false).
Statement of the theorem
A more explicit way of stating the theorem is:
Variations and implications
XOR-Form The statement also holds when the disjunction "+" is replaced by the XOR operator:
Dual form There is a dual form of the Shannon expansion (which does not have a related XOR form):
Repeated application for each argument leads to the Sum of Products (SoP) canonical form of the Boolean function . For example for that would be
Likewise, application of the dual form leads to the Product of Sums (PoS) canonical form (using the distributivity law of over ):
Properties of cofactors
Linear properties of cofactors:
For a Boolean function F which is made up of two Boolean functions G and H the following are true:
If then
If then
If then
If then
Characteristics of unate functions:
If F is a unate function and...
If F is positive unate then
If F is negative unate then
Operations with cofactors
Boolean difference:
The Boolean difference or Boolean derivative of the f
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https://en.wikipedia.org/wiki/Operational%20amplifier%20applications
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This article illustrates some typical operational amplifier applications. A non-ideal operational amplifier's equivalent circuit has a finite input impedance, a non-zero output impedance, and a finite gain. A real op-amp has a number of non-ideal features as shown in the diagram, but here a simplified schematic notation is used, many details such as device selection and power supply connections are not shown. Operational amplifiers are optimised for use with negative feedback, and this article discusses only negative-feedback applications. When positive feedback is required, a comparator is usually more appropriate. See Comparator applications for further information.
Practical considerations
Operational amplifiers parameter requirements
In order for a particular device to be used in an application, it must satisfy certain requirements. The operational amplifier must
have large open-loop signal gain (voltage gain of 200,000 is obtained in early integrated circuit exemplars), and
have input impedance large with respect to values present in the feedback network.
With these requirements satisfied, the op-amp is considered ideal, and one can use the method of virtual ground to quickly and intuitively grasp the 'behavior' of any of the op-amp circuits below.
Component specification
Resistors used in practical solid-state op-amp circuits are typically in the kΩ range. Resistors much greater than 1 MΩ cause excessive thermal noise and make the circuit operation susceptible to significant errors due to bias or leakage currents.
Input bias currents and input offset
Practical operational amplifiers draw a small current from each of their inputs due to bias requirements (in the case of bipolar junction transistor-based inputs) or leakage (in the case of MOSFET-based inputs).
These currents flow through the resistances connected to the inputs and produce small voltage drops across those resistances. Appropriate design of the feedback network can alleviate problems ass
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https://en.wikipedia.org/wiki/Litter%20%28zoology%29
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A litter is the live birth of multiple offspring at one time in animals from the same mother and usually from one set of parents, particularly from three to eight offspring. The word is most often used for the offspring of mammals, but can be used for any animal that gives birth to multiple young. In comparison, a group of eggs and the offspring that hatch from them are frequently called a clutch, while young birds are often called a brood. Animals from the same litter are referred to as litter-mates.
Litter
A species' average litter size is generally equal to one half of the number of teats and the maximum litter size generally matches the number of teats. Not all species abide by this rule, however. The naked mole rat, for example, averages roughly eleven young per birth and has eleven teats.
Animals frequently display grouping behavior in herds, swarms, flocks, or colonies, and these multiple births derive similar advantages. A litter offers some protection from predation, not particularly to the individual young but to the parents' investment in breeding. With multiple young, predators could eat several and others could still survive to reach maturity, but with only one offspring, its loss could mean a wasted breeding season. The other significant advantage is the chance for the healthiest young animals to be favored from a group. Rather than it being a conscious decision on the part of the parents, the fittest and strongest baby competes most successfully for food and space, leaving the weakest young, or runts, to die through lack of care.
In the wild, only a small percentage, if any, of the litter may survive to maturity, whereas for domesticated animals and those in captivity with human care the whole litter almost always survives. Kittens and puppies are in this group. Carnivorans, rodents, and pigs usually have litters, while primates and larger herbivores usually have singletons.
References
Zoology
Reproduction
Multiple births
Animals by adaptation
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https://en.wikipedia.org/wiki/Emergency%20power%20system
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An emergency power system is an independent source of electrical power that supports important electrical systems on loss of normal power supply. A standby power system may include a standby generator, batteries and other apparatus. Emergency power systems are installed to protect life and property from the consequences of loss of primary electric power supply. It is a type of continual power system.
They find uses in a wide variety of settings from homes to hospitals, scientific laboratories, data centers, telecommunication equipment and ships. Emergency power systems can rely on generators, deep-cycle batteries, flywheel energy storage or fuel cells.
History
Emergency power systems were used as early as World War II on naval ships. In combat, a ship may lose the function of its boilers, which power the steam turbines for the ship's generator. In such a case, one or more diesel engines are used to drive back-up generators. Early transfer switches relied on manual operation; two switches would be placed horizontally, in line and the "on" position facing each other. a rod is placed in between. In order to operate the switch one source must be turned off, the rod moved to the other side and the other source turned on.
Operation in buildings
Mains power can be lost due to downed lines, malfunctions at a sub-station, inclement weather, planned blackouts or in extreme cases a grid-wide failure. In modern buildings, most emergency power systems have been and are still based on generators. Usually, these generators are Diesel engine driven, although smaller buildings may use a gasoline engine driven generator.
Some larger building have gas turbines, but they can take 5 or up to 30 minutes to produce power.
Lately, more use is being made of deep cycle batteries and other technologies such as flywheel energy storage or fuel cells. These latter systems do not produce polluting gases, thereby allowing the placement to be done within the building. Also, as a second advan
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https://en.wikipedia.org/wiki/Port-Royal%20Logic
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Port-Royal Logic, or Logique de Port-Royal, is the common name of La logique, ou l'art de penser, an important textbook on logic first published anonymously in 1662 by Antoine Arnauld and Pierre Nicole, two prominent members of the Jansenist movement, centered on Port-Royal. Blaise Pascal likely contributed considerable portions of the text. Its linguistic companion piece is the Port-Royal Grammar (1660) by Arnauld and Lancelot.
Written in French, it became quite popular and was in use up to the twentieth century, introducing the reader to logic, and exhibiting strong Cartesian elements in its metaphysics and epistemology (Arnauld having been one of the main philosophers whose objections were published, with replies, in Descartes' Meditations on First Philosophy). The Port-Royal Logic is sometimes cited as a paradigmatic example of traditional term logic.
The philosopher Louis Marin particularly studied it in the 20th century (La Critique du discours, Éditions de Minuit, 1975), while Michel Foucault considered it, in The Order of Things, one of the bases of the classical épistémè.
Among the contributions of the Port-Royal Logic is the popularization of the distinction between comprehension and extension, which would later become a more refined distinction between intension and extension. Roughly speaking: a definition with more qualifications or features (the intension) denotes a class with fewer members (the extension), and vice versa.
The main idea traces back through the scholastic philosophers to Aristotle's ideas about genus and species, and is fundamental in the philosophy of Leibniz. More recently, it has been related to mathematical lattice theory in formal concept analysis, and independently formalized similarly by Yu. Schreider's group in Moscow, Jon Barwise & Jerry Seligman in Information Flow, and others.
References
Bibliography
Arnauld, Antoine, and Pierre Nicole. La logique ou l’Art de penser. 1st ed. Paris: Jean Guignart, Charles Savreux, & J
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https://en.wikipedia.org/wiki/Worm-like%20chain
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The worm-like chain (WLC) model in polymer physics is used to describe the behavior of polymers that are semi-flexible: fairly stiff with successive segments pointing in roughly the same direction, and with persistence length within a few orders of magnitude of the polymer length. The WLC model is the continuous version of the Kratky–Porod model.
Model elements
The WLC model envisions a continuously flexible isotropic rod. This is in contrast to the freely-jointed chain model, which is only flexible between discrete freely hinged segments. The model is particularly suited for describing stiffer polymers, with successive segments displaying a sort of cooperativity: nearby segments are roughly aligned. At room temperature, the polymer adopts a smoothly curved conformation; at K, the polymer adopts a rigid rod conformation.
For a polymer of maximum length , parametrize the path of the polymer as . Allow to be the unit tangent vector to the chain at point , and to be the position vector along the chain, as shown to the right. Then:
and the end-to-end distance .
The energy associated with the bending of the polymer can be written as:
where is the polymer's characteristic persistence length, is the Boltzmann constant, and is the absolute temperature. At finite temperatures, the end-to end distance of the polymer will be significantly shorter than the maximum length . This is caused by thermal fluctuations, which result in a coiled, random configuration of the undisturbed polymer.
The polymer's orientation correlation function can then be solved for, and it follows an exponential decay with decay constant 1/P:
A useful value is the mean square end-to-end distance of the polymer:
Note that in the limit of , then . This can be used to show that a Kuhn segment is equal to twice the persistence length of a worm-like chain. In the limit of , then , and the polymer displays rigid rod behavior. The figure to the right shows the crossover from flexible to stiff b
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https://en.wikipedia.org/wiki/Nomenclature%20codes
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Nomenclature codes or codes of nomenclature are the various rulebooks that govern biological taxonomic nomenclature, each in their own broad field of organisms. To an end-user who only deals with names of species, with some awareness that species are assignable to genera, families, and other taxa of higher ranks, it may not be noticeable that there is more than one code, but beyond this basic level these are rather different in the way they work.
The introduction of two-part names (binominal nomenclature) for species by Linnaeus was a welcome simplification because as our knowledge of biodiversity expanded, so did the length of the names, many of which had become unwieldy. With all naturalists worldwide adopting binominal nomenclature, there arose several schools of thought about the details. It became ever more apparent that a detailed body of rules was necessary to govern scientific names. From the mid-19th century onwards, there were several initiatives to arrive at worldwide-accepted sets of rules. Presently nomenclature codes govern the naming of:
Algae, Fungi and Plants – International Code of Nomenclature for algae, fungi, and plants (ICN), which in July 2011 replaced the International Code of Botanical Nomenclature (ICBN) and the earlier International Rules of Botanical Nomenclature.
Animals – International Code of Zoological Nomenclature (ICZN)
Bacteria and Archaea – International Code of Nomenclature of Prokaryotes (ICNP), which in 2008 replaced the International Code of Nomenclature of Bacteria (ICNB)
Bacteria and Archaea described from sequence data – Code of Nomenclature of Prokaryotes Described from Sequence Data (SeqCode)
Cultivated plants – International Code of Nomenclature for Cultivated Plants (ICNCP)
Plant associations – International Code of Phytosociological Nomenclature (ICPN)
Viruses – The International Code of Virus Classification and Nomenclature (ICVCN); see also virus classification
Differences between codes
Starting point
The s
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https://en.wikipedia.org/wiki/Random%20number%20generation
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Random number generation is a process by which, often by means of a random number generator (RNG), a sequence of numbers or symbols that cannot be reasonably predicted better than by random chance is generated. This means that the particular outcome sequence will contain some patterns detectable in hindsight but impossible to foresee. True random number generators can be hardware random-number generators (HRNGs), wherein each generation is a function of the current value of a physical environment's attribute that is constantly changing in a manner that is practically impossible to model. This would be in contrast to so-called "random number generations" done by pseudorandom number generators (PRNGs), which generate numbers that only look random but are in fact pre-determined—these generations can be reproduced simply by knowing the state of the PRNG.
Various applications of randomness have led to the development of different methods for generating random data. Some of these have existed since ancient times, including well-known examples like the rolling of dice, coin flipping, the shuffling of playing cards, the use of yarrow stalks (for divination) in the I Ching, as well as countless other techniques. Because of the mechanical nature of these techniques, generating large quantities of sufficiently random numbers (important in statistics) required much work and time. Thus, results would sometimes be collected and distributed as random number tables.
Several computational methods for pseudorandom number generation exist. All fall short of the goal of true randomness, although they may meet, with varying success, some of the statistical tests for randomness intended to measure how unpredictable their results are (that is, to what degree their patterns are discernible). This generally makes them unusable for applications such as cryptography. However, carefully designed cryptographically secure pseudorandom number generators (CSPRNGS) also exist, with special featur
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https://en.wikipedia.org/wiki/JavaStation
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The JavaStation was a Network Computer (NC) developed by Sun Microsystems between 1996 and 2000, intended to run only Java applications.
The hardware is based on the design of the Sun SPARCstation series, a very successful line of UNIX workstations.
The JavaStation, as an NC, lacks a hard drive, floppy or CD-ROM drive. It also differs from other Sun systems in having PS/2 keyboard and mouse interfaces and a VGA monitor connector.
Models
There were several models of the JavaStation produced, some being pre-production variants produced in very small numbers.
Production models comprised:
JavaStation-1 (part number JJ-xx), codenamed Mr. Coffee: based on a 110 MHz MicroSPARC IIe CPU, this was housed in a cuboidal Sun "unidisk" enclosure.
JavaStation-NC or JavaStation-10 (part number JK-xx) codenamed Krups: a redesigned Mr. Coffee with a 100 MHz MicroSPARC IIep CPU and enhanced video resolution and color capabilities. Krups was housed in a striking curved vertically oriented enclosure.
Models produced only as prototypes or in limited numbers included:
JavaStation/Fox: a prototype of the Mr Coffee: essentially a repackaged SPARCstation 4 Model 110.
JavaStation-E (part number JE-xx) codenamed Espresso: a Krups with PCI slots and a non-functional ATA interface in a restyled enclosure.
Dover: a JavaStation based on PC compatible hardware, with a Cyrix MediaGXm CPU.
JavaEngine-1: an ATX form-factor version of Krups for embedded systems.
A 68030-based system designed by Diba, Inc. (later acquired by Sun) circa 1996, which could be considered a very early JavaStation-like system.
In addition, Sun envisioned a third-generation "Super JavaStation" after Krups, with a JavaChip co-processor for native Java bytecode execution. This doesn't appear to have been produced.
The JavaStation concept was superseded by the Sun Ray series of thin client terminals.
Operating systems
The JavaStation comes with JavaOS in the flash memory, but it is also possible to install Linux
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https://en.wikipedia.org/wiki/Q15X25
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Q15X25 is a communications protocol for sending data over a radio link. It was designed by amateur radio operator Pawel Jalocha, SP9VRC, to be an open communications standard. Like all amateur radio communications modes, this protocol uses open transmissions which can be received and decoded by anyone with similar equipment. Q15X25 is a form of packet radio. It can be used to interconnect local VHF AX.25 packet networks over transcontinental distances. Anyone can design or adapt the open-source software to develop their own Q15X25 system.
Q15X25 is a digital signal processor-intensive mode designed to pass AX.25 packets on HF with speed and reliability much greater than traditional HF ARQ modems. It uses 15 QPSK modulated carriers separated by 125 Hertz, each modulated at 83.333 baud. Q15X25 uses forward error correction (FEC), and like MT63, uses time- and frequency-interleaving in order to avoid most error sources. The raw transmission data rate is typically 2500 bit/s.
Typically the DSP based receiver and transmitter modulator or codec is implemented as PC software that uses a sound card to connect directly to an SSB transceiver. Linux implementations are usually called "newpsk" or "newqpsk". MixW, a multipurpose communications control and digital modes package on Windows can implement Kiss and/or "TCP/IP over X.25" on either traditional 300 baud, 1200 baud and 2400 baud FSK packet "modems" implemented as DSP via sound card or over Q15X25. The "FlexNet" Windows packet software also has a newqpsk / Q15X25 option.
As with any amateur radio transmission, anyone can listen/decode Q15X25 transmissions, but an amateur radio operation license is required for transmission.
Frequencies (all USB) in use are (MixW center about 1350 Hz higher):
See also
Radioteletype
Shortwave
External links
ARRL description of Q15X25
MixW
Quantized radio modulation modes
Packet radio
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https://en.wikipedia.org/wiki/Warewulf
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Warewulf is a computer cluster implementation toolkit that facilitates the process of installing a cluster and long term administration. It does this by changing the administration paradigm to make all of the slave node file systems manageable from one point, and automate the distribution of the node file system during node boot. It allows a central administration model for all slave nodes and includes the tools needed to build configuration files, monitor, and control the nodes. It is totally customizable and can be adapted to just about any type of cluster. From the software administration perspective it does not make much difference if you are running 2 nodes or 500 nodes. The procedure is still the same, which is why Warewulf is scalable from the admins perspective. Also, because it uses a standard chroot'able file system for every node, it is extremely configurable and lends itself to custom environments very easily.
While Warewulf was designed to be a high-performance computing (HPC) system, it is not an HPC system in itself. Warewulf is more along the lines of a distributed Linux distribution, or more specifically a system for replicating and managing small, lightweight Linux systems from one master. Using Warewulf, HPC packages such as LAM/MPI/MPICH, Sun Grid Engine, PVM, etc. can be easily deployed throughout the cluster.
Warewulf solves the problem of slave node management rather than being a strict HPC specific system (even though it was designed with HPC in mind). Because of this it is as flexible as a home grown cluster, but administratively scales very well. As a result of this flexibility and ease of customization, Warewulf has been used not only on production HPC implementations, but also development systems like KASY0 (the first system to break the one hundred dollar per GFLOPS barrier), and non HPC systems such as web server cluster farms, intrusion detection clusters, and high-availability clusters.
See also
oneSIS – another diskless cluster p
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https://en.wikipedia.org/wiki/Primitive%20permutation%20group
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In mathematics, a permutation group G acting on a non-empty finite set X is called primitive if G acts transitively on X and the only partitions the G-action preserves are the trivial partitions into either a single set or into |X| singleton sets. Otherwise, if G is transitive and G does preserve a nontrivial partition, G is called imprimitive.
While primitive permutation groups are transitive, not all transitive permutation groups are primitive. The simplest example is the Klein four-group acting on the vertices of a square, which preserves the partition into diagonals. On the other hand, if a permutation group preserves only trivial partitions, it is transitive, except in the case of the trivial group acting on a 2-element set. This is because for a non-transitive action, either the orbits of G form a nontrivial partition preserved by G, or the group action is trivial, in which case all nontrivial partitions of X (which exists for |X| ≥ 3) are preserved by G.
This terminology was introduced by Évariste Galois in his last letter, in which he used the French term équation primitive for an equation whose Galois group is primitive.
Properties
In the same letter in which he introduced the term "primitive", Galois stated the following theorem:If G is a primitive solvable group acting on a finite set X, then the order of X is a power of a prime number p. Further, X may be identified with an affine space over the finite field with p elements, and G acts on X as a subgroup of the affine group.If the set X on which G acts is finite, its cardinality is called the degree of G.
A corollary of this result of Galois is that, if is an odd prime number, then the order of a solvable transitive group of degree is a divisor of In fact, every transitive group of prime degree is primitive (since the number of elements of a partition fixed by must be a divisor of ), and is the cardinality of the affine group of an affine space with elements.
It follows that, if is a prime
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https://en.wikipedia.org/wiki/Peukert%27s%20law
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Peukert's law, presented by the German scientist in 1897, expresses approximately the change in capacity of rechargeable lead–acid batteries at different rates of discharge. As the rate of discharge increases, the battery's available capacity decreases, approximately according to Peukert's law.
Batteries
Manufacturers specify the capacity of a battery at a specified discharge rate. For example, a battery might be rated at 100 A·h when discharged at a rate that will fully discharge the battery in 20 hours (at 5 amperes for this example). If discharged at a faster rate the delivered capacity is less. Peukert's law describes a power relationship between the discharge current (normalized to some base rated current) and delivered capacity (normalized to the rated capacity) over some specified range of discharge currents. If Peukert's constant , the exponent, were equal to unity, the delivered capacity would be independent of the current. For a real battery the exponent is greater than unity, and capacity decreases as discharge rate increases. For a lead–acid battery is typically between 1.1 and 1.3. For different lead-acid rechargeable battery technologies it generally ranges from 1.05 to 1.15 for VRSLAB AGM batteries, from 1.1 to 1.25 for gel, and from 1.2 to 1.6 for flooded batteries. The Peukert constant varies with the age of the battery, generally increasing (getting worse) with age. Application at low discharge rates must take into account the battery self-discharge current. At very high currents, practical batteries will give less capacity than predicted with a fixed exponent. The equation does not take into account the effect of temperature on battery capacity.
Formula
For a one-ampere discharge rate, Peukert's law is often stated as
where:
is the capacity at a one-ampere discharge rate, which must be expressed in ampere hours,
is the actual discharge current (i.e. current drawn from a load) in amperes,
is the actual time to discharge the battery, which m
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https://en.wikipedia.org/wiki/Phosphorescent%20organic%20light-emitting%20diode
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Phosphorescent organic light-emitting diodes (PHOLED) are a type of organic light-emitting diode (OLED) that use the principle of phosphorescence to obtain higher internal efficiencies than fluorescent OLEDs. This technology is currently under development by many industrial and academic research groups.
Method of operation
Like all types of OLED, phosphorescent OLEDs emit light due to the electroluminescence of an organic semiconductor layer in an electric current. Electrons and holes are injected into the organic layer at the electrodes and form excitons, a bound state of the electron and hole.
Electrons and holes are both fermions with half integer spin. An exciton is formed by the coulombic attraction between the electron and the hole, and it may either be in a singlet state or a triplet state, depending on the spin states of these two bound species. Statistically, there is a 25% probability of forming a singlet state and 75% probability of forming a triplet state. Decay of the excitons results in the production of light through spontaneous emission.
In OLEDs using fluorescent organic molecules only, the decay of triplet excitons is quantum mechanically forbidden by selection rules, meaning that the lifetime of triplet excitons is long and phosphorescence is not readily observed. Hence it would be expected that in fluorescent OLEDs only the formation of singlet excitons results in the emission of useful radiation, placing a theoretical limit on the internal quantum efficiency (the percentage of excitons formed that result in emission of a photon) of 25%.
However, phosphorescent OLEDs generate light from both triplet and singlet excitons, allowing the internal quantum efficiency of such devices to reach nearly 100%.
This is commonly achieved by doping a host molecule with an organometallic complex. These contain a heavy metal atom at the centre of the molecule, for example platinum or iridium, of which the green emitting complex Ir(mppy)3 is just one of ma
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https://en.wikipedia.org/wiki/Promotional%20video
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In video production, a promotional video is marketing or advertising:
Arts, media and entertainment
Promotional recording, an audio or video recording distributed to publicize a recording
Trailer (promotion), a commercial advertisement for a feature film
Music video, a short film that integrates a song with imagery
Corporate use
Corporate video, non-advertisement media created for and commissioned by an organization
Personal use
Video resume, a recording used to promote a jobseeker
Promotional dating video, a video dating recording made to find a romantic partner
References
Video
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https://en.wikipedia.org/wiki/John%20Pinkerton%20%28computer%20designer%29
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John Maurice McClean Pinkerton (2 August 1919 – 22 December 1997) was a pioneering British computer designer. Along with David Caminer, he designed England's first business computer, the LEO computer, produced by J. Lyons and Co in 1951.
Personal life
John Pinkerton was educated at King Edward's School, Bath, and Clifton College, Bristol. He studied at Trinity College, Cambridge from 1937 to 1940, reading Natural Sciences, and graduating with first class honours. He joined the Air Ministry Research Establishment in Swanage, to work on radar, and went with it to Malvern where it was renamed the Telecommunications Research Establishment (where he met Maurice Wilkes). He returned to Cambridge as a research student at the Cavendish Laboratory.
In 1948 he married Helen McCorkindale. They had a son and a daughter.
Colleagues describe him as having "a disarming way of listening intently to what others said", a "quiet, dry sense of humour", a "fine, critical, but constructive intelligence", "an enviable ability to handle detail", and "friendliness and kindness". They also mention his knowledge of music and English literature and his lively appreciation of good food.
J. Lyons
The catering firm of J. Lyons was known in the high street for its tea and cakes; in the business world it was known for its innovative approach to supply chain management. As early as 1947 the firm decided that the future lay with computers, and since nothing suitable was available, they resolved to build one. They approached Wilkes in Cambridge, who suggested that they construct a copy of the EDSAC machine, and introduced them to Pinkerton whom they recruited as chief engineer.
Pinkerton's approach was to leave the design unchanged as far as possible, while improving reliability by identifying the points of failure (notably electronic valves) and developing test procedures that enabled component failures to be anticipated and prevented.
The machine went into operation in early 1951, and was us
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https://en.wikipedia.org/wiki/Karyolysis
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Karyolysis (from Greek κάρυον karyon—kernel, seed, or nucleus), and λύσις lysis from λύειν lyein, "to separate") is the complete dissolution of the chromatin of a dying cell due to the enzymatic degradation by endonucleases. The whole cell will eventually stain uniformly with eosin after karyolysis. It is usually associated with karyorrhexis and occurs mainly as a result of necrosis, while in apoptosis after karyorrhexis the nucleus usually dissolves into apoptotic bodies.
Disintegration of the cytoplasm, pyknosis of the nuclei, and karyolysis of the nuclei of scattered transitional cells may be seen in urine from healthy individuals as well as in urine containing malignant cells. Cells with an attached tag of partially preserved cytoplasm were initially described by Papanicolaou and are sometimes called comet or decoy cells. They may have some of the characteristics of malignancy, and it is therefore important that they be recognized for what they are.
Additional images
See also
Apoptosis
Necrosis
Pyknosis
Karyorrhexis
References
Cellular processes
Cellular senescence
Programmed cell death
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https://en.wikipedia.org/wiki/HMAC-based%20one-time%20password
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HMAC-based one-time password (HOTP) is a one-time password (OTP) algorithm based on HMAC. It is a cornerstone of the Initiative for Open Authentication (OATH).
HOTP was published as an informational IETF RFC 4226 in December 2005, documenting the algorithm along with a Java implementation. Since then, the algorithm has been adopted by many companies worldwide (see below). The HOTP algorithm is a freely available open standard.
Algorithm
The HOTP algorithm provides a method of authentication by symmetric generation of human-readable passwords, or values, each used for only one authentication attempt. The one-time property leads directly from the single use of each counter value.
Parties intending to use HOTP must establish some ; typically these are specified by the authenticator, and either accepted or not by the authenticated:
A cryptographic hash method H (default is SHA-1)
A secret key K, which is an arbitrary byte string and must remain private
A counter C, which counts the number of iterations
A HOTP value length d (6–10, default is 6, and 6–8 is recommended)
Both parties compute the HOTP value derived from the secret key K and the counter C. Then the authenticator checks its locally generated value against the value supplied by the authenticated.
The authenticator and the authenticated increment the counter C independently of each other, where the latter may increase ahead of the former, thus a resynchronisation protocol is wise. does not actually require any such, but does make a recommendation. This simply has the authenticator repeatedly try verification ahead of their counter through a window of size s. The authenticator's counter continues forward of the value at which verification succeeds and requires no actions by the authenticated.
The recommendation is made that persistent throttling of HOTP value verification take place, to address their relatively small size and thus vulnerability to brute-force attacks. It is suggested that verificatio
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https://en.wikipedia.org/wiki/Old%20Baldy%20%28horse%29
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Old Baldy (ca. 1852 – December 16, 1882) was the horse ridden by Union Major General George G. Meade at the Battle of Gettysburg and in many other important battles of the American Civil War.
Early life and Civil War service
Baldy was born and raised on the western frontier and at the start of the Civil War was owned by Maj. Gen. David Hunter. His name during this period is unknown. It is said that he was wounded anywhere from five to 14 times during the war, starting at the First Battle of Bull Run, where he was struck in the nose by a piece of an artillery shell. Soon after, in September 1861, he was purchased from the government by Meade in Washington, D.C., for $150 and named Baldy because of his white face.
Despite Baldy's unusual, uncomfortable pace, Meade became quite devoted to him and rode him in all of his battles through 1862 and the spring of 1863. The horse was wounded in the right hind leg at the Second Battle of Bull Run, and at Antietam, he was wounded through the neck and left for dead on the field. He survived and was treated. At Gettysburg, on July 2, 1863, Baldy was hit by a bullet that entered his stomach after passing through Meade's right trouser leg. He staggered and refused to move forward, defying all of Meade's directions. Meade commented, "Baldy is done for this time. This is the first time he has refused to go forward under fire." Baldy was sent to the rear for recuperation. In 1864, having returned to duty for the Overland Campaign and the Siege of Petersburg, he was struck in the ribs by a shell at the Weldon Railroad, and Meade decided that Old Baldy should be retired.
Retirement and death
Baldy was sent north to Philadelphia and then to the farm of Meade's staff quartermaster, Captain Sam Ringwalt, in Downingtown, Pennsylvania. He was later relocated to the Meadow Bank Farm, owned by a friend of the Meade family, where he remained for several years. He was moderately active in retirement and Meade rode the horse in several me
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https://en.wikipedia.org/wiki/Numbers%20in%20Egyptian%20mythology
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Certain numbers were considered sacred, holy, or magical by the ancient Egyptians, particularly 2, 3, 4, 7, and their multiples and sums.
Three: symbol of plurality
The basic symbol for plurality among the ancient Egyptians was the number three: even the way they wrote the word for "plurality" in hieroglyphics consisted of three vertical marks (𓏼). Triads of deities were also used in Egyptian religion to signify a complete system. Examples include references to the god Atum "when he was one and became three" when he gave birth to Shu and Tefnut, and the triad of Horus, Osiris, and Isis.
Examples
The beer used to trick Sekhmet soaked three hands into the ground.
The second god, Re, named three times to define the sun: dawn, noon, and evening.
Thoth is described as the “thrice-great god of wisdom”.
A doomed prince was doomed to three fates: to die by a crocodile, a serpent, or a dog.
Three groups of three attempts each (nine attempts) were required for a legendary peasant to recover his stolen goods.
A boasting mage claimed to be able to cast a great darkness to last three days.
After asking Thoth for help, a King of Ethiopia was brought to Thebes and publicly beaten three further times.
An Ethiopian mage tried—and failed—three times to defeat the greatest mage of Egypt.
An Egyptian mage, in an attempt to enter the land of the dead, threw a certain powder on a fire three times.
There are twelve (three times four) sections of the Egyptian land of the dead. The dead disembark at the third.
The Knot of Isis, representing life, has three loops.
Five
Examples
The second god, Rê, named five gods and goddesses.
Thoth added five days to the year by winning the light from the Moon in a game of gambling.
It took five days for the five children of Nut and Geb to be born. These are Osiris, Nephthys, Isis, Set and Haroeris (Horus the Elder) - not be mistaken with Harpocrates (Horus the Younger), who defeated Set in battle.
A boasting mage claimed to be able to bring the Ph
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https://en.wikipedia.org/wiki/Symmetric%20equilibrium
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In game theory, a symmetric equilibrium is an equilibrium where all players use the same strategy (possibly mixed) in the equilibrium. In the Prisoner's Dilemma game pictured to the right, the only Nash equilibrium is (D, D). Since both players use the same strategy, the equilibrium is symmetric.
Symmetric equilibria have important properties. Only symmetric equilibria can be evolutionarily stable states in single population models.
See also
Symmetric game
References
Game theory equilibrium concepts
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https://en.wikipedia.org/wiki/DPLL%20algorithm
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In logic and computer science, the Davis–Putnam–Logemann–Loveland (DPLL) algorithm is a complete, backtracking-based search algorithm for deciding the satisfiability of propositional logic formulae in conjunctive normal form, i.e. for solving the CNF-SAT problem.
It was introduced in 1961 by Martin Davis, George Logemann and Donald W. Loveland and is a refinement of the earlier Davis–Putnam algorithm, which is a resolution-based procedure developed by Davis and Hilary Putnam in 1960. Especially in older publications, the Davis–Logemann–Loveland algorithm is often referred to as the "Davis–Putnam method" or the "DP algorithm". Other common names that maintain the distinction are DLL and DPLL.
Implementations and applications
The SAT problem is important both from theoretical and practical points of view. In complexity theory it was the first problem proved to be NP-complete, and can appear in a broad variety of applications such as model checking, automated planning and scheduling, and diagnosis in artificial intelligence.
As such, writing efficient SAT solvers has been a research topic for many years. GRASP (1996-1999) was an early implementation using DPLL. In the international SAT competitions, implementations based around DPLL such as zChaff and MiniSat were in the first places of the competitions in 2004 and 2005.
Another application that often involves DPLL is automated theorem proving or satisfiability modulo theories (SMT), which is a SAT problem in which propositional variables are replaced with formulas of another mathematical theory.
The algorithm
The basic backtracking algorithm runs by choosing a literal, assigning a truth value to it, simplifying the formula and then recursively checking if the simplified formula is satisfiable; if this is the case, the original formula is satisfiable; otherwise, the same recursive check is done assuming the opposite truth value. This is known as the splitting rule, as it splits the problem into two simpler sub-p
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https://en.wikipedia.org/wiki/X-ray%20absorption%20spectroscopy
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X-ray absorption spectroscopy (XAS) is a widely used technique for determining the local geometric and/or electronic structure of matter. The experiment is usually performed at synchrotron radiation facilities, which provide intense and tunable X-ray beams. Samples can be in the gas phase, solutions, or solids.
Background
XAS data is obtained by tuning the photon energy, using a crystalline monochromator, to a range where core electrons can be excited (0.1-100 keV). The edges are, in part, named by which core electron is excited: the principal quantum numbers n = 1, 2, and 3, correspond to the K-, L-, and M-edges, respectively. For instance, excitation of a 1s electron occurs at the K-edge, while excitation of a 2s or 2p electron occurs at an L-edge (Figure 1).
There are three main regions found on a spectrum generated by XAS data which are then thought of as separate spectroscopic techniques (Figure 2):
The absorption threshold determined by the transition to the lowest unoccupied states:
The X-ray absorption near-edge structure (XANES), introduced in 1980 and later in 1983 and also called NEXAFS (near-edge X-ray absorption fine structure), which are dominated by core transitions to quasi bound states (multiple scattering resonances) for photoelectrons with kinetic energy in the range from 10 to 150 eV above the chemical potential, called "shape resonances" in molecular spectra since they are due to final states of short life-time degenerate with the continuum with the Fano line-shape. In this range multi-electron excitations and many-body final states in strongly correlated systems are relevant;
In the high kinetic energy range of the photoelectron, the scattering cross-section with neighbor atoms is weak, and the absorption spectra are dominated by EXAFS (extended X-ray absorption fine structure), where the scattering of the ejected photoelectron of neighboring atoms can be approximated by single scattering events. In 1985, it was shown that multiple scat
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https://en.wikipedia.org/wiki/American%20National%20Corpus
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The American National Corpus (ANC) is a text corpus of American English containing 22 million words of written and spoken data produced since 1990. Currently, the ANC includes a range of genres, including emerging genres such as email, tweets, and web data that are not included in earlier corpora such as the British National Corpus. It is annotated for part of speech and lemma, shallow parse, and named entities.
The ANC is available from the Linguistic Data Consortium. A fifteen million word subset of the corpus, called the Open American National Corpus (OANC), is freely available with no restrictions on its use from the ANC Website.
The corpus and its annotations are provided according to the specifications of ISO/TC 37 SC4's Linguistic Annotation Framework. By using a freely provided transduction tool (ANC2Go), the corpus and user-chosen annotations are provided in multiple formats, including CoNLL IOB format, the XML format conformant to the XML Corpus Encoding Standard (XCES) (usable with the British National Corpus's XAIRA search engine), a UIMA-compliant format, and formats suitable for input to a wide variety of concordance software. Plugins to import the annotations into General Architecture for Text Engineering (GATE) are also available.
The ANC differs from other corpora of English because it is richly annotated, including different part of speech annotations (Penn tags, CLAWS5 and CLAWS7 tags), shallow parse annotations, and annotations for several types of named entities. Additional annotations are added to all or parts of the corpus as they become available, often by contributions from other projects. Unlike on-line searchable corpora, which due to copyright restrictions allow access only to individual sentences, the entire ANC is available to enable research involving, for example, development of statistical language models and full-text linguistic annotation.
ANC annotations are automatically produced and unvalidated.
A 500,000 word subset call
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https://en.wikipedia.org/wiki/Turbo%20Dispatch
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Turbo Dispatch is a public domain standard for the electronic transfer of job details, initially using packet radio, but now also using the internet. It is used throughout the United Kingdom to pass the details of stranded motorists between all the major UK motoring organisations and their 400 plus vehicle recovery agents. In many cases it is also used by the vehicle recovery agent to pass the details to the attending recovery vehicle.
History
On 30 June 1994, a group of representatives from the UK seven major motoring organisations and the Institute of Vehicle Recovery were invited a meeting at Brooklands Museum. Brooklands Museum was chosen as the venue because the meeting's chairman Andy Lambert was involved with the museum, having transported the vast majority of the exhibits there, and could therefore show people items they would not normally get to see. He clearly hoped that this would be enough incentive to get ‘the clubs’ to sit-down in the same room together. It soon emerged that it was a shared dream of all those present that ‘common standards’ for all aspects of vehicle recovery could be introduced to the industry. Amongst other things, this group laid the foundations of Turbo Dispatch project.
Because of the reliability of delivery needed it was decided that Mobitex should be used. In the UK there was only one provider of Mobitex, namely RAM Data, which later became a subsidiary of BT called Transcomm. This is why many users still refer to RAMing jobs. Ian Lane of Motor Trade Software (MTS) designed and wrote the protocols along with the gateway software. Much pioneering work was carried out during early 1995. In the autumn of 1995 Green Flag and Delta Rescue were the first motoring organisations to start experimenting with transmissions to the garages, with the first genuine job being sent to Southbank Garage at the end of the year.
The point where most recovery operators learned about Turbo Dispatch was during the Association of Vehicle Recovery O
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https://en.wikipedia.org/wiki/Articulated%20robot
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An articulated robot is a robot with rotary joints (e.g. a legged robot or an industrial robot). Articulated robots can range from simple two-jointed structures to systems with 10 or more interacting joints and materials.
They are powered by a variety of means, including electric motors.
Some types of robots, such as robotic arms, can be articulated or non-articulated.
Articulated robots in action
Definitions
Articulated Robot:
See Figure. An articulated robot uses all the three revolute joints to access its work space.
Usually the joints are arranged in a “chain”, so that one joint supports another further in the chain.
Continuous Path:
A control scheme whereby the inputs or commands specify every point along a desired path of motion. The path is controlled by the coordinated motion of the manipulator joints.
Degrees Of Freedom (DOF):
The number of independent motions in which the end effector can move, defined by the number of axes of motion of the manipulator.
Gripper:
A device for grasping or holding, attached to the free end of the last manipulator link; also called the robot’s hand or end-effector.
Payload:
The maximum payload is the amount of weight carried by the robot manipulator at reduced speed while maintaining rated precision. Nominal payload is measured at maximum speed while maintaining rated precision. These ratings are highly dependent on the size and shape of the payload.
Pick And Place Cycle:
See Figure. Pick and place Cycle is the time, in seconds, to execute the following motion sequence: Move down one inch, grasp a rated payload; move up one inch; move across twelve inches; move down one inch; ungrasp; move up one inch; and return to start location.
Reach:
The maximum horizontal distance from the center of the robot base to the end of its wrist.
Accuracy:
See Figure. The difference between the point that a robot is trying to achieve and the actual resultant position. Absolute accuracy is the difference between a point instructed by
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https://en.wikipedia.org/wiki/Thermodynamic%20state
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In thermodynamics, a thermodynamic state of a system is its condition at a specific time; that is, fully identified by values of a suitable set of parameters known as state variables, state parameters or thermodynamic variables. Once such a set of values of thermodynamic variables has been specified for a system, the values of all thermodynamic properties of the system are uniquely determined. Usually, by default, a thermodynamic state is taken to be one of thermodynamic equilibrium. This means that the state is not merely the condition of the system at a specific time, but that the condition is the same, unchanging, over an indefinitely long duration of time.
Thermodynamics sets up an idealized conceptual structure that can be summarized by a formal scheme of definitions and postulates. Thermodynamic states are amongst the fundamental or primitive objects or notions of the scheme, for which their existence is primary and definitive, rather than being derived or constructed from other concepts.
A thermodynamic system is not simply a physical system. Rather, in general, infinitely many different alternative physical systems comprise a given thermodynamic system, because in general a physical system has vastly many more microscopic characteristics than are mentioned in a thermodynamic description. A thermodynamic system is a macroscopic object, the microscopic details of which are not explicitly considered in its thermodynamic description. The number of state variables required to specify the thermodynamic state depends on the system, and is not always known in advance of experiment; it is usually found from experimental evidence. The number is always two or more; usually it is not more than some dozen. Though the number of state variables is fixed by experiment, there remains choice of which of them to use for a particular convenient description; a given thermodynamic system may be alternatively identified by several different choices of the set of state variables.
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https://en.wikipedia.org/wiki/Biological%20thermodynamics
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Biological thermodynamics (Thermodynamics of biological systems) is a science that explains the nature and general laws of thermodynamic processes occurring in living organisms as nonequilibrium thermodynamic systems that convert the energy of the Sun and food into other types of energy. The nonequilibrium thermodynamic state of living organisms is ensured by the continuous alternation of cycles of controlled biochemical reactions, accompanied by the release and absorption of energy, which provides them with the properties of phenotypic adaptation and a number of others.
History
In 1935, the first scientific work devoted to the thermodynamics of biological systems was published - the book of the Hungarian-Russian theoretical biologist Erwin S. Bauer (1890-1938) "Theoretical Biology"[]. E. Bauer formulated the "Universal Law of Biology" in the following edition: "All and only living systems are never in equilibrium and perform constant work at the expense of their free energy against the equilibrium required by the laws of physics and chemistry under existing external conditions". This law can be considered the 1st law of thermodynamics of biological systems.
In 1957, German-British physician and biochemist Hans Krebs and British-American biochemist Hans Kornberg[] in the book "Energy Transformations in Living Matter" first described the thermodynamics of biochemical reactions. In their works, H. Krebs and Hans Kornberg showed how in living cells, as a result of biochemical reactions, adenosine triphosphate (ATP) is synthesized from food, which is the main source of energy of living organisms (the Krebs–Kornberg cycle).
In 2006, the Israeli-Russian scientist Boris Dobroborsky (1945) published the book "Thermodynamics of Biological Systems"[], in which the general principles of functioning of living organisms from the perspective of nonequilibrium thermodynamics were formulated for the first time and the nature and properties of their basic physiological function
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https://en.wikipedia.org/wiki/Synergetics%20%28Haken%29
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Synergetics is an interdisciplinary science explaining the formation and self-organization of patterns and structures in open systems far from thermodynamic equilibrium. It is founded by Hermann Haken, inspired by the laser theory. Haken's interpretation of the laser principles as self-organization of non-equilibrium systems paved the way at the end of the 1960s to the development of synergetics. One of his successful popular books is Erfolgsgeheimnisse der Natur, translated into English as The Science of Structure: Synergetics.
Self-organization requires a 'macroscopic' system, consisting of many nonlinearly interacting subsystems. Depending on the external control parameters (environment, energy fluxes) self-organization takes place.
Order-parameter concept
Essential in synergetics is the order-parameter concept which was originally introduced in the Ginzburg–Landau theory in order to describe phase transitions in thermodynamics. The order parameter concept is generalized by Haken to the "enslaving-principle" saying that the dynamics of fast-relaxing (stable) modes is completely determined by the 'slow' dynamics of, as a rule, only a few 'order-parameters' (unstable modes). The order parameters can be interpreted as the amplitudes of the unstable modes determining the macroscopic pattern.
As a consequence, self-organization means an enormous reduction of degrees of freedom (entropy) of the system which macroscopically reveals an increase of 'order' (pattern-formation). This far-reaching macroscopic order is independent of the details of the microscopic interactions of the subsystems. This supposedly explains the self-organization of patterns in so many different systems in physics, chemistry and biology.
See also
Effective field theory
Josiah Willard Gibbs
Phase rule
Free energy principle
Fokker–Planck equation
Ginzburg–Landau theory
Buckminster Fuller
Alexander Bogdanov
Abiogenesis
References
A. S. Mikhailov: Foundations of Synergetics I
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https://en.wikipedia.org/wiki/Quasi-invariant%20measure
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In mathematics, a quasi-invariant measure μ with respect to a transformation T, from a measure space X to itself, is a measure which, roughly speaking, is multiplied by a numerical function of T. An important class of examples occurs when X is a smooth manifold M, T is a diffeomorphism of M, and μ is any measure that locally is a measure with base the Lebesgue measure on Euclidean space. Then the effect of T on μ is locally expressible as multiplication by the Jacobian determinant of the derivative (pushforward) of T.
To express this idea more formally in measure theory terms, the idea is that the Radon–Nikodym derivative of the transformed measure μ′ with respect to μ should exist everywhere; or that the two measures should be equivalent (i.e. mutually absolutely continuous):
That means, in other words, that T preserves the concept of a set of measure zero. Considering the whole equivalence class of measures ν, equivalent to μ, it is also the same to say that T preserves the class as a whole, mapping any such measure to another such. Therefore, the concept of quasi-invariant measure is the same as invariant measure class.
In general, the 'freedom' of moving within a measure class by multiplication gives rise to cocycles, when transformations are composed.
As an example, Gaussian measure on Euclidean space Rn is not invariant under translation (like Lebesgue measure is), but is quasi-invariant under all translations.
It can be shown that if E is a separable Banach space and μ is a locally finite Borel measure on E that is quasi-invariant under all translations by elements of E, then either dim(E) < +∞ or μ is the trivial measure μ ≡ 0.
See also
References
Measures (measure theory)
Dynamical systems
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