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https://en.wikipedia.org/wiki/Edge%20and%20vertex%20spaces
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In the mathematical discipline of graph theory, the edge space and vertex space of an undirected graph are vector spaces defined in terms of the edge and vertex sets, respectively. These vector spaces make it possible to use techniques of linear algebra in studying the graph.
Definition
Let be a finite undirected graph. The vertex space of G is the vector space over the finite field of two elements
of all functions . Every element of naturally corresponds the subset of V which assigns a 1 to its vertices. Also every subset of V is uniquely represented in by its characteristic function. The edge space is the -vector space freely generated by the edge set E. The dimension of the vertex space is thus the number of vertices of the graph, while the dimension of the edge space is the number of edges.
These definitions can be made more explicit. For example, we can describe the edge space as follows:
elements are subsets of , that is, as a set is the power set of E
vector addition is defined as the symmetric difference:
scalar multiplication is defined by:
The singleton subsets of E form a basis for .
One can also think of as the power set of V made into a vector space with similar vector addition and scalar multiplication as defined for .
Properties
The incidence matrix for a graph defines one possible linear transformation
between the edge space and the vertex space of . The incidence matrix of , as a linear transformation, maps each edge to its two incident vertices. Let be the edge between and then
The cycle space and the cut space are linear subspaces of the edge space.
References
(the electronic 3rd edition is freely available on author's site).
See also
cycle space
cut space
Algebraic graph theory
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https://en.wikipedia.org/wiki/Libdvdcss
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libdvdcss (or libdvdcss2 in some repositories) is a free and open-source software library for accessing and unscrambling DVDs encrypted with the Content Scramble System (CSS). libdvdcss is part of the VideoLAN project and is used by VLC media player and other DVD player software packages, such as Ogle, xine-based players, and MPlayer.
Comparison with DeCSS
libdvdcss is not to be confused with DeCSS. Whereas DeCSS uses a cracked DVD player key to perform authentication, libdvdcss uses a generated list of possible player keys. If none of them work (for instance, when the DVD drive enforces region coding), libdvdcss brute-forces the key, ignoring the DVD's region code (if any). The legal status of libdvdcss is controversial but there has been—unlike DeCSS—no known legal challenge to it as of June 2022.
Distribution
Many Linux distributions do not contain libdvdcss (for example, Debian, Ubuntu, Fedora and openSUSE) due to fears of running afoul of DMCA-style laws, but they often provide the tools to let the user install it themselves. For example, it used to be available in Ubuntu through Medibuntu, which is no longer available.
Distributions which come pre-installed with libdvdcss include BackTrack, CrunchBang Linux, LinuxMCE, Linux Mint, PCLinuxOS, Puppy Linux 4.2.1, Slax, Super OS, Pardus, and XBMC Live.
It is also in Arch Linux official package repositories.
Usage
Libdvdcss alone is only a library and cannot play DVDs. DVD player applications, such as VLC media player, use this library to decode DVDs. Libdvdcss is optional in many open-source DVD players, but without it, only non-encrypted discs will play.
Using HandBrake or VidCoder for DVD ripping requires that one install libdvdcss (with compilation or Homebrew on macOS)
See also
Advanced Access Content System
Blu-ray
References
External links
C (programming language) libraries
Compact Disc and DVD copy protection
Cryptographic software
DVD
Free codecs
Free computer libraries
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https://en.wikipedia.org/wiki/Topological%20module
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In mathematics, a topological module is a module over a topological ring such that scalar multiplication and addition are continuous.
Examples
A topological vector space is a topological module over a topological field.
An abelian topological group can be considered as a topological module over where is the ring of integers with the discrete topology.
A topological ring is a topological module over each of its subrings.
A more complicated example is the -adic topology on a ring and its modules. Let be an ideal of a ring The sets of the form for all and all positive integers form a base for a topology on that makes into a topological ring. Then for any left -module the sets of the form for all and all positive integers form a base for a topology on that makes into a topological module over the topological ring
See also
References
Algebra
Topology
Topological algebra
Topological groups
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https://en.wikipedia.org/wiki/141%20%28number%29
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141 (one hundred [and] forty-one) is the natural number following 140 and preceding 142.
In mathematics
141 is:
a centered pentagonal number.
the sum of the sums of the divisors of the first 13 positive integers.
the second n to give a prime Cullen number (of the form n2n + 1).
an undulating number in base 10, with the previous being 131, and the next being 151.
the sixth hendecagonal (11-gonal) number.
a semiprime: a product of two prime numbers, namely 3 and 47. Since those prime factors are Gaussian primes, this means that 141 is a Blum integer.
a Hilbert prime
In the military
The Lockheed C-141 Starlifter was a United States Air Force military strategic airlifter
K-141 Kursk was a Russian nuclear cruise missile submarine, which sank in the Barents Sea on 12 August 2000
was a United States Navy ship during World War II
was a United States Navy during World War II
was a United States Navy during World War II
was a United States Navy following World War I
was a United States Navy during World War II
In transportation
London Buses route 141 is a Transport for London contracted bus route in London
141 Nottingham–Sutton-in-Ashfield is a bus route in England
The 141 C Ouest was a 2-8-2 steam locomotive of the Chemin de fer de l'État
British Rail Class 141 was the first production model of the Pacer diesel multiple units
Union des Transports Africains de Guinée Flight 141, which crashed in the Bight of Benin on December 25, 2003
The Saipa 141 car produced by SAIPA
The Córas Iompair Éireann 141 class locomotive from General Motors Electro-Motive Division in 1962
In other fields
141 is also:
The year AD 141 or 141 BC
141 AH is a year in the Islamic calendar that corresponds to 759 – 760 CE
141 Lumen is a dark C-type, rocky asteroid orbiting in the asteroid belt
The atomic number of unquadunium, a temporary chemical element
The telephone dialing prefix for withholding one's Caller ID in the United Kingdom
Psalm 141
Sonnet 141 by William
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https://en.wikipedia.org/wiki/Generic%20cell%20rate%20algorithm
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The generic cell rate algorithm (GCRA) is a leaky bucket-type scheduling algorithm for the network scheduler that is used in Asynchronous Transfer Mode (ATM) networks. It is used to measure the timing of cells on virtual channels (VCs) and or Virtual Paths (VPs) against bandwidth and jitter limits contained in a traffic contract for the VC or VP to which the cells belong. Cells that do not conform to the limits given by the traffic contract may then be re-timed (delayed) in traffic shaping, or may be dropped (discarded) or reduced in priority (demoted) in traffic policing. Nonconforming cells that are reduced in priority may then be dropped, in preference to higher priority cells, by downstream components in the network that are experiencing congestion. Alternatively they may reach their destination (VC or VP termination) if there is enough capacity for them, despite them being excess cells as far as the contract is concerned: see priority control.
The GCRA is given as the reference for checking the traffic on connections in the network, i.e. usage/network parameter control (UPC/NPC) at user–network interfaces (UNI) or inter-network interfaces or network-network interfaces (INI/NNI) . It is also given as the reference for the timing of cells transmitted (ATM PDU Data_Requests) onto an ATM network by a network interface card (NIC) in a host, i.e. on the user side of the UNI . This ensures that cells are not then discarded by UPC/NCP in the network, i.e. on the network side of the UNI. However, as the GCRA is only given as a reference, the network providers and users may use any other algorithm that gives the same result.
Description of the GCRA
The GCRA is described by the ATM Forum in its User-Network Interface (UNI) and by the ITU-T in recommendation I.371 Traffic control and congestion control in B-ISDN . Both sources describe the GCRA in two equivalent ways: as a virtual scheduling algorithm and as a continuous state leaky bucket algorithm (figure 1).
Lea
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https://en.wikipedia.org/wiki/Adulterant
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An adulterant is caused by the act of adulteration, a practice of secretly mixing a substance with another. Typical substances that are adulterated include but are not limited to food, cosmetics, pharmaceuticals, fuel, or other chemicals, that compromise the safety or effectiveness of the said substance.
It will not normally be present in any specification or declared substances due to accident or negligence rather than intent, and also for the introduction of unwanted substances after the product has been made. Adulteration, therefore, implies that the adulterant was introduced deliberately in the initial manufacturing process, or sometimes that it was present in the raw materials and should have been removed, but was not.
An adulterant is distinct from, for example, permitted food preservatives. There can be a fine line between adulterant and additive; chicory may be added to coffee to reduce the cost or achieve a desired flavor—this is adulteration if not declared, but may be stated on the label. Chalk was often added to bread flour; this reduces the cost and increases whiteness, but the calcium confers health benefits, and in modern bread, a little chalk may be included as an additive for this reason.
In wartime, adulterants have been added to make foodstuffs "go further" and prevent shortages. The German word ersatz is widely recognised for such practices during World War II. Such adulteration was sometimes deliberately hidden from the population to prevent loss of morale and propaganda reasons. Some goods considered luxurious in the Soviet Bloc such as coffee were adulterated to make them affordable to the general population.
In food and beverages
Past and present examples of adulterated food, some dangerous, include:
Apple jellies (jams), as substitutes for more expensive fruit jellies, with added colorant and sometimes even specks of wood that simulate raspberry or strawberry seeds
High fructose corn syrup or cane sugar, used to adulterate honey
Red
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https://en.wikipedia.org/wiki/Carbon%20chauvinism
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Carbon chauvinism is a neologism meant to disparage the assumption that the chemical processes of hypothetical extraterrestrial life must be constructed primarily from carbon (organic compounds) because as far as is known, carbon's chemical and thermodynamic properties render it far superior to all other elements at forming molecules used in living organisms.
The expression "carbon chauvinism" is also used to criticize the idea that artificial intelligence can't in theory be sentient or truly intelligent because the underlying matter isn't biological.
Concept
The term was used as early as 1973, when scientist Carl Sagan described it and other human chauvinisms that limit imagination of possible extraterrestrial life. It suggests that human beings, as carbon-based life forms who have never encountered any life that has evolved outside the Earth's environment, may find it difficult to envision radically different biochemistries.
Carbon alternatives
Like carbon, silicon can form four stable bonds with itself and other elements, and long chemical chains known as silane polymers, which are very similar to the hydrocarbons essential to life on Earth. Silicon is more reactive than carbon, which could make it optimal for extremely cold environments. However, silanes spontaneously burn in the presence of oxygen at relatively low temperatures, so an oxygen atmosphere may be deadly to silicon-based life. On the other hand, it is worth considering that alkanes are as a rule quite flammable, but carbon-based life on Earth does not store energy directly as alkanes, but as sugars, lipids, alcohols, and other hydrocarbon compounds with very different properties. Water as a solvent would also react with silanes, but again, this only matters if for some reason silanes are used or mass-produced by such organisms.
Silicon lacks an important property of carbon: single, double, and triple carbon-carbon bonds are all relatively stable. Aromatic carbon structures underpin DNA, which c
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https://en.wikipedia.org/wiki/Bridgman%27s%20thermodynamic%20equations
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In thermodynamics, Bridgman's thermodynamic equations are a basic set of thermodynamic equations, derived using a method of generating multiple thermodynamic identities involving a number of thermodynamic quantities. The equations are named after the American physicist Percy Williams Bridgman. (See also the exact differential article for general differential relationships).
The extensive variables of the system are fundamental. Only the entropy S , the volume V and the four most common thermodynamic potentials will be considered. The four most common thermodynamic potentials are:
{|
|-----
| Internal energy || U
|-----
| Enthalpy || H
|-----
| Helmholtz free energy || A
|-----
| Gibbs free energy || G
|-----
|}
The first derivatives of the internal energy with respect to its (extensive) natural variables S and V yields the intensive parameters of the system - The pressure P and the temperature T . For a simple system in which the particle numbers are constant, the second derivatives of the thermodynamic potentials can all be expressed in terms of only three material properties
{|
|-----
| heat capacity (constant pressure) || CP
|-----
| Coefficient of thermal expansion || α
|-----
| Isothermal compressibility || βT
|}
Bridgman's equations are a series of relationships between all of the above quantities.
Introduction
Many thermodynamic equations are expressed in terms of partial derivatives. For example, the expression for the heat capacity at constant pressure is:
which is the partial derivative of the enthalpy with respect to temperature while holding pressure constant. We may write this equation as:
This method of rewriting the partial derivative was described by Bridgman (and also Lewis & Randall), and allows the use of the following collection of expressions to express many thermodynamic equations. For example from the equations below we have:
and
Dividing, we recover the proper expression for CP.
The following summary restates various partial
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https://en.wikipedia.org/wiki/Safety%20engineer
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Safety engineers focus on development and maintenance of the integrated management system. They act as a quality assurance and conformance specialist.
Health and safety engineers are responsible for developing and maintaining the safe work systems for employees and others.
Scope of role
The scope of a safety engineer is the development and maintenance of the integrated management system. Safety engineering professionals must have a thorough understanding of legislation, standards and systems. They need to have a fundamental knowledge of safety, contract law, tort, environmental law, policy, health, construction, computer science, engineering, labour hire, plant hire, communication and psychology. Professional safety studies include construction and engineering, architectural design of systemss, fire protection, ergonomics, system and process safety, system safety, safety and health program management, accident investigation and analysis, product safety, construction safety, education and training methods, measurement of safety performance, human behavior, environmental safety and health, and safety, health and environmental laws, regulations and standards. Many safety engineers have backgrounds or advanced study in other disciplines, such as occupational health and safety, construction management and civil engineering, engineering, system engineering / industrial engineering, requirements engineering, reliability engineering, maintenance, human factors, operations, education, physical and social sciences and other fields. This extends their expertise beyond the basics of health and safety.
Personality and role
They must be personally pleasant, intelligent, and ruthless with themselves and their organisation. In particular, they have to be able to "sell" the failures that they discover to inspectors/ auditors, as well as the attendant expense and time needed to correct them. Often facts can be uncomfortable for the business.
Safety engineers have to be ruthles
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https://en.wikipedia.org/wiki/Booth%27s%20multiplication%20algorithm
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Booth's multiplication algorithm is a multiplication algorithm that multiplies two signed binary numbers in two's complement notation. The algorithm was invented by Andrew Donald Booth in 1950 while doing research on crystallography at Birkbeck College in Bloomsbury, London. Booth's algorithm is of interest in the study of computer architecture.
The algorithm
Booth's algorithm examines adjacent pairs of bits of the 'N'-bit multiplier Y in signed two's complement representation, including an implicit bit below the least significant bit, y−1 = 0. For each bit yi, for i running from 0 to N − 1, the bits yi and yi−1 are considered. Where these two bits are equal, the product accumulator P is left unchanged. Where yi = 0 and yi−1 = 1, the multiplicand times 2i is added to P; and where yi = 1 and yi−1 = 0, the multiplicand times 2i is subtracted from P. The final value of P is the signed product.
The representations of the multiplicand and product are not specified; typically, these are both also in two's complement representation, like the multiplier, but any number system that supports addition and subtraction will work as well. As stated here, the order of the steps is not determined. Typically, it proceeds from LSB to MSB, starting at i = 0; the multiplication by 2i is then typically replaced by incremental shifting of the P accumulator to the right between steps; low bits can be shifted out, and subsequent additions and subtractions can then be done just on the highest N bits of P. There are many variations and optimizations on these details.
The algorithm is often described as converting strings of 1s in the multiplier to a high-order +1 and a low-order −1 at the ends of the string. When a string runs through the MSB, there is no high-order +1, and the net effect is interpretation as a negative of the appropriate value.
A typical implementation
Booth's algorithm can be implemented by repeatedly adding (with ordinary unsigned binary addition) one of two
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https://en.wikipedia.org/wiki/Pteridophyte
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A pteridophyte is a vascular plant (with xylem and phloem) that disperses spores. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as "cryptogams", meaning that their means of reproduction is hidden.
Ferns, horsetails (often treated as ferns), and lycophytes (clubmosses, spikemosses, and quillworts) are all pteridophytes. However, they do not form a monophyletic group because ferns (and horsetails) are more closely related to seed plants than to lycophytes. "Pteridophyta" is thus no longer a widely accepted taxon, but the term pteridophyte remains in common parlance, as do pteridology and pteridologist as a science and its practitioner, respectively.
Ferns and lycophytes share a life cycle and are often collectively treated or studied, for example by the International Association of Pteridologists and the Pteridophyte Phylogeny Group.
Description
Pteridophytes (ferns and lycophytes) are free-sporing vascular plants that have a life cycle with alternating, free-living gametophyte and sporophyte phases that are independent at maturity. The body of the sporophyte is well differentiated into roots, stem and leaves. The root systems is always adventitious. The stem is either underground or aerial. The leaves may be microphylls or megaphylls. Their other common characteristics include vascular plant apomorphies (e.g., vascular tissue) and land plant plesiomorphies (e.g., spore dispersal and the absence of seeds).
Taxonomy
Phylogeny
Of the pteridophytes, ferns account for nearly 90% of the extant diversity. Smith et al. (2006), the first higher-level pteridophyte classification published in the molecular phylogenetic era, considered the ferns as monilophytes, as follows:
Division Tracheophyta (tracheophytes) - vascular plants
Subdivision Lycopodiophyta (lycophytes) - less than 1% of extant vascular plants
Sub division Euphyllophytina (euphyllophytes)
Infradivision Moniliformopses (monilophytes)
Infradivision Spermatophyta -
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https://en.wikipedia.org/wiki/Mercury-arc%20valve
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A mercury-arc valve or mercury-vapor rectifier or (UK) mercury-arc rectifier is a type of electrical rectifier used for converting high-voltage or high-current alternating current (AC) into direct current (DC). It is a type of cold cathode gas-filled tube, but is unusual in that the cathode, instead of being solid, is made from a pool of liquid mercury and is therefore self-restoring. As a result mercury-arc valves, when used as intended, are far more robust and durable and can carry much higher currents than most other types of gas discharge tube. Some examples have been in continuous service, rectifying 50-ampere currents, for decades.
Invented in 1902 by Peter Cooper Hewitt, mercury-arc rectifiers were used to provide power for industrial motors, electric railways, streetcars, and electric locomotives, as well as for radio transmitters and for high-voltage direct current (HVDC) power transmission. They were the primary method of high power rectification before the advent of semiconductor rectifiers, such as diodes, thyristors and gate turn-off thyristors (GTOs) in the 1970s. These solid state rectifiers have almost completely replaced mercury-arc rectifiers thanks to their higher reliability, lower cost and maintenance and lower environmental risk.
History
In 1882 Jules Jamin and G. Maneuvrier observed the rectifying properties of a mercury arc. The mercury arc rectifier was invented by Peter Cooper Hewitt in 1902 and further developed throughout the 1920s and 1930s by researchers in both Europe and North America. Before its invention, the only way to convert AC current provided by utilities to DC was by using expensive, inefficient, and high-maintenance rotary converters or motor–generator sets. Mercury-arc rectifiers or "converters" were used for charging storage batteries, arc lighting systems, the DC traction motors for trolleybuses, trams, and subways, and electroplating equipment. The mercury rectifier was used well into the 1970s, when it was finall
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https://en.wikipedia.org/wiki/Quadrature%20%28geometry%29
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In mathematics, particularly in geometry, quadrature (also called squaring) is a historical process of drawing a square with the same area as a given plane figure or computing the numerical value of that area. A classical example is the quadrature of the circle (or squaring the circle).
Quadrature problems served as one of the main sources of problems in the development of calculus. They introduce important topics in mathematical analysis.
History
Antiquity
Greek mathematicians understood the determination of an area of a figure as the process of geometrically constructing a square having the same area (squaring), thus the name quadrature for this process. The Greek geometers were not always successful (see squaring the circle), but they did carry out quadratures of some figures whose sides were not simply line segments, such as the lune of Hippocrates and the parabola. By a certain Greek tradition, these constructions had to be performed using only a compass and straightedge, though not all Greek mathematicians adhered to this dictum.
For a quadrature of a rectangle with the sides a and b it is necessary to construct a square with the side (the geometric mean of a and b). For this purpose it is possible to use the following: if one draws the circle with diameter made from joining line segments of lengths a and b, then the height (BH in the diagram) of the line segment drawn perpendicular to the diameter, from the point of their connection to the point where it crosses the circle, equals the geometric mean of a and b. A similar geometrical construction solves the problems of quadrature of a parallelogram and of a triangle.
Problems of quadrature for curvilinear figures are much more difficult. The quadrature of the circle with compass and straightedge was proved in the 19th century to be impossible. Nevertheless, for some figures a quadrature can be performed. The quadratures of the surface of a sphere and a parabola segment discovered by Archimedes became the
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https://en.wikipedia.org/wiki/KOI-7
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KOI-7 (КОИ-7) is a 7-bit character encoding, designed to cover Russian, which uses the Cyrillic alphabet.
In Russian, KOI-7 stands for Kod Obmena Informatsiey, 7 bit (Код Обмена Информацией, 7 бит) which means "Code for Information Exchange, 7 bit".
It was first standardized in GOST 13052-67 (with the 2nd revision GOST 13052-74 / ST SEV 356-76) and GOST 27463-87 / ST SEV 356-86.
Shift Out (SO) and Shift In (SI) control characters are used in KOI-7, where SO starts printing Russian letters (KOI-7 N1), and SI starts printing Latin letters again (KOI-7 N0), or for lowercase and uppercase switching. This version is also known as KOI7-switched aka csKOI7switched.
On ISO 2022 compatible computer terminals KOI7-switched can be activated by the escape sequence ESC ( @ ESC ) N LS0.
KOI-7 was used on machines like the SM EVM (СМ ЭВМ) and DVK (ДВК); KOI-7 N2 was utilized in the machine-language of the (Elektronika D3-28) as four-digit hexadecimal code, (BESM-6), where it was called ВКД, (internal data code). The encodings were also used on RSX-11, RT-11 and similar systems.
KOI-7 N0
KOI-7 N0 (КОИ-7 Н0) is identical to the IRV set in ISO 646:1967. Compared to US-ASCII, the dollar sign ("$") at code point 24 (hex) was replaced by the universal currency sign "¤", but this was not maintained in all cases, in particular not after the fall of the Iron Curtain. Likewise, the IRV set in ISO/IEC 646:1991 also changed the character back to a dollar sign.
KOI-7 N1
KOI-7 N1 (КОИ-7 Н1) was first standardized in GOST 13052-67, and later also in ISO 5427. It is sometimes referred to as "koi-0" as well.
Compared to ASCII and ISO 646 uppercase and lowercase letters are swapped in order to make it easier to recognize Russian text when presented using ASCII.
To trim the alphabet into chunks of 32 characters the dotted Ё/ë was dropped. In order to avoid conflicts with ASCII's and ISO 646's definition as DEL and its usage as EOF marker (-1) in some systems, it dropped the "CAPITAL HARD
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https://en.wikipedia.org/wiki/Cabletron%20Systems
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Cabletron Systems, Inc., was a manufacturer of networking computer equipment throughout the 1980s and 1990s primarily based in Rochester, New Hampshire, in the United States. They also had manufacturing facilities in Ironton, Ohio, and in Ireland.
History
Cabletron was founded in 1983 in a Massachusetts garage by Craig Benson (who later became New Hampshire's governor) and Robert Levine. As manufacturing and design operations expanded, Cabletron relocated to Rochester, New Hampshire, employing 6,600 people at its peak. In 1996 the company eclipsed US$1 billion in sales. Cabletron found its first success in the 10BASE5 Ethernet market, providing the ST-500, the first Ethernet transceiver that featured diagnostic LEDs, and the LAN-MD, the first commercially viable field-deployable 10BASE5 test set. The early products were critical in the history of Ethernet as 10BASE5 Ethernet was generally difficult to operate and maintain and cabling problems were especially difficult to diagnose. Following on this early success, Cabletron developed one of the first modular Ethernet hubs, the MMAC-8 (and its smaller siblings, the MMAC-5 and the MMAC-3) at the time that 10BASE-T was becoming standardized. By developing high-density 10BASE-T modules (24 or 48 ports per slot), Cabletron was able to reduce the price per port of these hubs to a very affordable level, and by introducing a custom Element Management System known as Prism, made the MMAC-8 easy to maintain.
As Cabletron expanded its reach in the networking business, they initially moved into Layer 3 routing by partnering with Cisco, co-developing a Cisco router that would fit into the MMAC-8 hub. Cabletron ultimately developed its own routing capability, but found it increasingly difficult to compete at the low end of the Ethernet market and continue to invest in high-end routing technology.
Recognizing this fact, Cabletron reorganized as a holding company in 2000, hoping to apply appropriate focus to the different parts
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https://en.wikipedia.org/wiki/World%20Wide%20Web%20Virtual%20Library
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The World Wide Web Virtual Library (WWW VL) was the first index of content on the World Wide Web and still operates as a directory of e-texts and information sources on the web.
Overview
The Virtual Library was started by Tim Berners-Lee creator of HTML and the World Wide Web itself, in 1991 at CERN in Geneva. Unlike commercial index sites, it is run by a loose confederation of volunteers, who compile pages of key links for particular areas in which they are experts. It is sometimes informally referred to as the "WWWVL", the "Virtual Library" or just "the VL".
The individual indexes, or virtual libraries live on hundreds of different servers around the world. A set of index pages linking these individual libraries is maintained at vlib.org, in Geneva only a few kilometres from where the VL began life. A mirror of this index is kept at East Anglia in the United Kingdom.
History
The Virtual Library was first conceived and run by Tim Berners-Lee in 1991, and later expanded, organised and managed for several years by Arthur Secret as the "virtual librarian", before it became a formally established association with Gerard Manning as its Council's first chairman. The late Bertrand Ibrahim was a key contributor to the pre-association phase of the Virtual Library's development and then served as its Secretary until his untimely death in 2001 at the age of 46. A brief history, with links to archived pages and screenshots, is maintained on the Vlib website.
The Virtual Library grew over the years. For example, there is the WWW-VL History Central Catalogue, which was launched on 21 September 1993 by Lynn H. Nelson at Kansas University. From April 2004, it was relocated at the European University Institute, Florence, Italy, where a history of the catalogue is also available. The Virtual Library museums pages (VLmp) were added by Jonathan Bowen to the Virtual Library to cover museums in 1994.
In 2005, the central WWW Virtual Library website (vlib.org) was taken over by a ne
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https://en.wikipedia.org/wiki/Q-analog
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In mathematics, a q-analog of a theorem, identity or expression is a generalization involving a new parameter q that returns the original theorem, identity or expression in the limit as . Typically, mathematicians are interested in q-analogs that arise naturally, rather than in arbitrarily contriving q-analogs of known results. The earliest q-analog studied in detail is the basic hypergeometric series, which was introduced in the 19th century.
q-analogs are most frequently studied in the mathematical fields of combinatorics and special functions. In these settings, the limit is often formal, as is often discrete-valued (for example, it may represent a prime power).
q-analogs find applications in a number of areas, including the study of fractals and multi-fractal measures, and expressions for the entropy of chaotic dynamical systems. The relationship to fractals and dynamical systems results from the fact that many fractal patterns have the symmetries of Fuchsian groups in general (see, for example Indra's pearls and the Apollonian gasket) and the modular group in particular. The connection passes through hyperbolic geometry and ergodic theory, where the elliptic integrals and modular forms play a prominent role; the q-series themselves are closely related to elliptic integrals.
q-analogs also appear in the study of quantum groups and in q-deformed superalgebras. The connection here is similar, in that much of string theory is set in the language of Riemann surfaces, resulting in connections to elliptic curves, which in turn relate to q-series.
"Classical" q-theory
Classical q-theory begins with the q-analogs of the nonnegative integers. The equality
suggests that we define the q-analog of n, also known as the q-bracket or q-number of n, to be
By itself, the choice of this particular q-analog among the many possible options is unmotivated. However, it appears naturally in several contexts. For example, having decided to use [n]q as the q-analog of n, on
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https://en.wikipedia.org/wiki/Data%20Matrix
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A Data Matrix is a two-dimensional code consisting of black and white "cells" or dots arranged in either a square or rectangular pattern, also known as a matrix. The information to be encoded can be text or numeric data. Usual data size is from a few bytes up to 1556 bytes. The length of the encoded data depends on the number of cells in the matrix. Error correction codes are often used to increase reliability: even if one or more cells are damaged so it is unreadable, the message can still be read. A Data Matrix symbol can store up to 2,335 alphanumeric characters.
Data Matrix symbols are rectangular, usually square in shape and composed of square "cells" which represent bits. Depending on the coding used, a "light" cell represents a 0 and a "dark" cell is a 1, or vice versa. Every Data Matrix is composed of two solid adjacent borders in an "L" shape (called the "finder pattern") and two other borders consisting of alternating dark and light "cells" or modules (called the "timing pattern"). Within these borders are rows and columns of cells encoding information. The finder pattern is used to locate and orient the symbol while the timing pattern provides a count of the number of rows and columns in the symbol. As more data is encoded in the symbol, the number of cells (rows and columns) increases. Each code is unique. Symbol sizes vary from 10×10 to 144×144 in the new version ECC 200, and from 9×9 to 49×49 in the old version ECC 000 – 140.
Applications
The most popular application for Data Matrix is marking small items, due to the code's ability to encode fifty characters in a symbol that is readable at and the fact that the code can be read with only a 20% contrast ratio.
A Data Matrix is scalable; commercial applications exist with images as small as (laser etched on a silicon device) and as large as a 1 metre (3 ft) square (painted on the roof of a boxcar). Fidelity of the marking and reading systems are the only limitation.
The US Electronic Industries A
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https://en.wikipedia.org/wiki/Algebraic%20graph%20theory
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Algebraic graph theory is a branch of mathematics in which algebraic methods are applied to problems about graphs. This is in contrast to geometric, combinatoric, or algorithmic approaches. There are three main branches of algebraic graph theory, involving the use of linear algebra, the use of group theory, and the study of graph invariants.
Branches of algebraic graph theory
Using linear algebra
The first branch of algebraic graph theory involves the study of graphs in connection with linear algebra. Especially, it studies the spectrum of the adjacency matrix, or the Laplacian matrix of a graph (this part of algebraic graph theory is also called spectral graph theory). For the Petersen graph, for example, the spectrum of the adjacency matrix is (−2, −2, −2, −2, 1, 1, 1, 1, 1, 3). Several theorems relate properties of the spectrum to other graph properties. As a simple example, a connected graph with diameter D will have at least D+1 distinct values in its spectrum. Aspects of graph spectra have been used in analysing the synchronizability of networks.
Using group theory
The second branch of algebraic graph theory involves the study of graphs in connection to group theory, particularly automorphism groups and geometric group theory. The focus is placed on various families of graphs based on symmetry (such as symmetric graphs, vertex-transitive graphs, edge-transitive graphs, distance-transitive graphs, distance-regular graphs, and strongly regular graphs), and on the inclusion relationships between these families. Certain of such categories of graphs are sparse enough that lists of graphs can be drawn up. By Frucht's theorem, all groups can be represented as the automorphism group of a connected graph (indeed, of a cubic graph). Another connection with group theory is that, given any group, symmetrical graphs known as Cayley graphs can be generated, and these have properties related to the structure of the group.
This second branch of algebraic graph theory
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https://en.wikipedia.org/wiki/Platonic%20hydrocarbon
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In organic chemistry, a Platonic hydrocarbon is a hydrocarbon (molecule) whose structure matches one of the five Platonic solids, with carbon atoms replacing its vertices, carbon–carbon bonds replacing its edges, and hydrogen atoms as needed.
Not all Platonic solids have molecular hydrocarbon counterparts; those that do are the tetrahedron (tetrahedrane), the cube (cubane), and the dodecahedron (dodecahedrane).
Tetrahedrane
Tetrahedrane (C4H4) is a hypothetical compound. It has not yet been synthesized without substituents, but it is predicted to be kinetically stable in spite of its angle strain. Some stable derivatives, including tetra(tert-butyl)tetrahedrane (a hydrocarbon) and tetra(trimethylsilyl)tetrahedrane, have been produced.
Cubane
Cubane (C8H8) has been synthesized. Although it has high angle strain, cubane is kinetically stable, due to a lack of readily available decomposition paths.
Octahedrane
Angle strain would make an octahedron highly unstable due to inverted tetrahedral geometry at each vertex. There would also be no hydrogen atoms because four edges meet at each corner; thus, the hypothetical octahedrane molecule would be an allotrope of elemental carbon, C6, and not a hydrocarbon. The existence of octahedrane cannot be ruled out completely, although calculations have shown that it is unlikely.
Dodecahedrane
Dodecahedrane (C20H20) was first synthesized in 1982, and has minimal angle strain; the tetrahedral angle is 109.5° and the dodecahedral angle is 108°, only a slight discrepancy.
Icosahedrane
The tetravalency (4-connectedness) of carbon excludes an icosahedron because 5 edges meet at each vertex. True pentavalent carbon is unlikely; methanium, nominally , usually exists as . The hypothetical icosahedral lacks hydrogen so it is not a hydrocarbon; it is also an ion.
Both icosahedral and octahedral structures have been observed in boron compounds such as the dodecaborate ion and some of the carbon-containing carboranes.
Other polyhedr
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https://en.wikipedia.org/wiki/Fieldbus
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A fieldbus is a member of a family of industrial digital communication networks used for real-time distributed control. Fieldbus profiles are standardized by the
International Electrotechnical Commission (IEC) as IEC 61784/61158.
A complex automated industrial system is typically structured in hierarchical levels as a distributed control system (DCS). In this hierarchy the upper levels for production managements are linked to the direct control level of programmable logic controllers (PLC) via a non-time-critical communications system (e.g. Ethernet). The fieldbus links the PLCs of the direct control level to the components in the plant of the field level such as sensors, actuators, electric motors, console lights, switches, valves and contactors and replaces the direct connections via current loops or digital I/O signals. The requirement for a fieldbus are therefore time-critical and cost sensitive. Since the new millennium a number of fieldbuses based on Real-time Ethernet have been established. These have the potential to replace traditional fieldbuses in the long term.
Description
A fieldbus is an industrial network system for real-time distributed control. It is a way to connect instruments in a manufacturing plant. A fieldbus works on a network structure which typically allows daisy-chain, star, ring, branch, and tree network topologies. Previously, computers were connected using RS-232 (serial connections) by which only two devices could communicate. This would be the equivalent of the currently used 4–20 mA communication scheme which requires that each device have its own communication point at the controller level, while the fieldbus is the equivalent of the current LAN-type connections, which require only one communication point at the controller level and allow multiple (hundreds) of analog and digital points to be connected at the same time. This reduces both the length of the cable required and the number of cables required. Furthermore, since devic
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https://en.wikipedia.org/wiki/Pythagorean%20hammers
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According to legend, Pythagoras discovered the foundations of musical tuning by listening to the sounds of four blacksmith's hammers, which produced consonance and dissonance when they were struck simultaneously. According to Nicomachus in his 2nd-century CE Enchiridion harmonices, Pythagoras noticed that hammer A produced consonance with hammer B when they were struck together, and hammer C produced consonance with hammer A, but hammers B and C produced dissonance with each other. Hammer D produced such perfect consonance with hammer A that they seemed to be "singing" the same note. Pythagoras rushed into the blacksmith shop to discover why, and found that the explanation was in the weight ratios. The hammers weighed 12, 9, 8, and 6 pounds respectively. Hammers A and D were in a ratio of 2:1, which is the ratio of the octave. Hammers B and C weighed 8 and 9 pounds. Their ratios with hammer D were (12:8 = 3:2 = perfect fifth) and (12:9 = 4:3 = perfect fourth). The space between B and C is a ratio of 9:8, which is equal to the musical whole tone, or whole step interval ().
The legend is, at least with respect to the hammers, demonstrably false. It is probably a Middle Eastern folk tale. These proportions are indeed relevant to string length (e.g. that of a monochord) — using these founding intervals, it is possible to construct the chromatic scale and the basic seven-tone diatonic scale used in modern music, and Pythagoras might well have been influential in the discovery of these proportions (hence, sometimes referred to as Pythagorean tuning) — but the proportions do not have the same relationship to hammer weight and the tones produced by them. However, hammer-driven chisels with equal cross-section, show an exact proportion between length or weight and Eigenfrequency.
Earlier sources mention Pythagoras' interest in harmony and ratio. Xenocrates (4th century BCE), while not as far as we know mentioning the blacksmith story, described Pythagoras' interest in gen
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https://en.wikipedia.org/wiki/International%20Society%20of%20Automation
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The International Society of Automation (ISA), formerly known as The Instrumentation, Systems, and Automation Society, is a non-profit technical society for engineers, technicians, businesspeople, educators and students, who work, study or are interested in automation and pursuits related to it, such as instrumentation. It was originally known as the Instrument Society of America. The society is more commonly known by its acronym, ISA, and the society's scope now includes many technical and engineering disciplines.
ISA is one of the foremost professional organizations in the world for setting standards and educating industry professionals in automation. Instrumentation and automation are some of the key technologies involved in nearly all industrialized manufacturing. Modern industrial manufacturing is a complex interaction of numerous systems. Instrumentation provides regulation for these complex systems using many different measurement and control devices. Automation provides the programmable devices that permit greater flexibility in the operation of these complex manufacturing systems.
In 2019, ISA announced the formation of the ISA Global Cybersecurity Alliance to promote the ISA/IEC 62443 series of standards, which are the world’s only consensus-based cybersecurity standard for automation and control system applications.
Structure
The International Society of Automation is a non-profit member-driven organization, which is built on a backbone of volunteers. Volunteers, working together with the ISA's full-time staff of over 75, are key to the ongoing mission and success of the organization. The ISA has a strong leadership development program that develops volunteer leaders as they get involved with the organization's many different facets. ISA has several different ways that volunteers get involved from the section, division, and standards roots of the organization.
ISA members are typically assigned an ISA Section (local chapter) which is related to their g
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https://en.wikipedia.org/wiki/Jacek%20Karpi%C5%84ski
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Jacek Karpiński (9 April 1927 21 February 2010) was a Polish pioneer in computer engineering and computer science.
During World War II, he was a soldier in the Batalion Zośka of the Polish Home Army, and was awarded multiple times with a Cross of Valour. He took part in Operation Kutschera (intelligence) and the Warsaw Uprising, where he was heavily wounded.
Later, he became a developer of one of the first machine learning algorithms, techniques for character and image recognition.
After receiving a UNESCO award in 1960, he travelled for several years around the academic centres in the United States, including MIT, Harvard, Caltech, and many others.
In 1971, he designed one of the first minicomputers, the K-202. Because of the policy on computer development in the People's Republic of Poland, belonging to the Comecon that time, the K-202 was never mass-produced.
Karpiński later became a pig farmer, and in 1981, after receiving a passport, emigrated to Switzerland.
He also founded the Laboratory for Artificial Intelligence of the Polish Academy of Sciences in the early 1960s.
Family and childhood
Jacek Karpiński was born on 9 April 1927 in Turin, Italy into a family of Polish intellectuals and alpinists. His father, Adam 'Akar' Karpiński, was a prominent aeronautic engineer (who co-constructed the SL-1 Akar, the first glider constructed entirely by the Poles) and inventor, credited with projects of innovative climbing equipment (crampons, 'Akar-Ramada' tent). His mother, Wanda Czarnocka-Karpińska, was a respected physician who went on to become Dean of the University of Physical Education in Warsaw. Both were pioneers of winter mountaineering in the Tatra Mountains (first successful winter attacks on Banówka, Nowy Wierch, Lodowy Szczyt and others). Adam Karpiński was also a member of a Polish expedition into the Andes, which was the first to climb the peak Mercedario (6720 m.). Karpiński himself was due to be born in the Vallot winter hut near Mont Blanc, but
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https://en.wikipedia.org/wiki/Robert%20Kowalski
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Robert Anthony Kowalski (born 15 May 1941) is an American-British logician and computer scientist, whose research is concerned with developing both human-oriented models of computing and computational models of human thinking. He has spent most of his career in the United Kingdom.
Education
He was educated at the University of Chicago, University of Bridgeport (BA in mathematics, 1963), Stanford University (MSc in mathematics, 1966), University of Warsaw and the University of Edinburgh (PhD in computer science, 1970).
Career
He was a research fellow at the University of Edinburgh (1970–75) and has been at the Department of Computing, Imperial College London since 1975, attaining a chair in Computational logic in 1982 and becoming Emeritus Professor in 1999.
He began his research in the field of automated theorem proving, developing both SL-resolution with Donald Kuehner and the connection graph proof procedure. He developed SLD resolution and the procedural interpretation of Horn clauses, which underpin the operational semantics of backward reasoning in logic programming. With Maarten van Emden, he also developed the minimal model and the fixpoint semantics of Horn clauses, which underpin the logical semantics of logic programming.
With Marek Sergot, he developed both the event calculus and the application of logic programming to legal reasoning. With Fariba Sadri, he developed an agent model in which beliefs are represented by logic programs and goals are represented by integrity constraints.
Kowalski was one of the developers of abductive logic programming, in which logic programs are augmented with integrity constraints and with undefined, abducible predicates. This work led to the demonstration with Phan Minh Dung and Francesca Toni that most logics for default reasoning can be regarded as special cases of assumption-based argumentation.
In his 1979 book, Logic for Problem Solving, Kowalski argues that logical inference provides a simple and powerful mode
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https://en.wikipedia.org/wiki/Communications%20and%20networking%20riser
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Communications and networking riser (CNR) is a slot found on certain PC motherboards and used for specialized networking, audio, and telephony equipment. A motherboard manufacturer can choose to provide audio, networking, or modem functionality in any combination on a CNR card. CNR slots were once commonly found on Pentium III-class motherboards, but have since been phased out in favor of on-board or embedded components.
Technology
Physically, a CNR slot has two rows of 30 pins, with two possible pin configurations: Type A and Type B, each with different pin assignments. CNR Type A uses 8-pin PHY interface, while Type B uses 17-pin media-independent interface (MII) bus LAN interface. Both types carry USB and AC'97 signals.
As with AMR, CNR had the cost savings potential for manufacturers by removing analog I/O components from the motherboard. This allowed the manufacturer to only certify with the US Federal Communications Commission (FCC) for the CNR card, and not the entire motherboard. This resulted in a quicker production-to-market time for new motherboards, and allowed mass-production of CNR cards to be used on multiple motherboards.
The ACR slot was a competing specification developed by a group of third-party vendors. Its principal advantage over CNR was the backwards-compatible slot layout which allowed it to use both AMR and ACR cards. The same group also developed a physically smaller version, the MDC.
History
Intel developed the CNR slot to replace its own audio/modem riser (AMR) technology, drawing on two distinct advantages over the AMR slot it replaced; CNR was both capable of being either software based (CPU-controlled) or hardware accelerated (dedicated ASIC), and was plug-and-play compatible. On some motherboards, a CNR slot replaced the last PCI slot, but most motherboard manufacturers engineered boards which allow the CNR and last PCI slot to share the same space.
With the integration of components such as ethernet and audio into the mother
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https://en.wikipedia.org/wiki/Alex%20%28videotex%20service%29
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Alex was the name of an interactive videotex information service offered by Bell Canada in market research from 1988 to 1990 and thence to the general public until 1994.
The Alextel terminal was based on the French Minitel terminals, built by Northern Telecom and leased to customers for $7.95/month. It consisted of a CRT display, attached keyboard, and a 1200 bit/s modem for use on regular phone lines. In 1991 proprietary software was released for IBM PCs that allowed computer users to access the network. Communications on the Alex network was via DATAPAC X.25 protocol.
The system operated in the same fashion as Minitel, whereby users connected to various content providers over the X.25 network and thus access was normally through a local telephone number. The most popular (and most expensive) sites were chat rooms. Using the service could cost as much as per minute. Also offered was an electronic white pages and yellow pages directory. Many users terminated their subscription upon receiving their first invoice. One subscriber racked up a monthly fee of over C$2,000 spending most of his online time in chat.
History
The motivation to develop the Alex terminal and online service came from competitive pressure from France's Minitel, which had expanded into the Quebec market.
Bell Canada received approval from the CRTC to offer the online service as of November 1988.
The advent of the World Wide Web contributed to making this service obsolete. On April 29, 1994, Bell Canada sent a letter to its customers announcing that the service would be terminated on June 3, 1994. In that letter, Mr. T.E. Graham, then Director of Business Planning for Bell Advanced Communications, stated that "Quite simply, the ALEX network is not the right vehicle, nor the appropriate technology, at this time to deliver the information goods needed in our fast-paced society."
The Alextel terminal is reportedly usable as a dumb terminal for VT100 emulation.
Further reading
Proulx, Serge
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https://en.wikipedia.org/wiki/E-commerce%20payment%20system
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An e-commerce payment system (or an electronic payment system) facilitates the acceptance of electronic payment for offline transfer, also known as a subcomponent of electronic data interchange (EDI), e-commerce payment systems have become increasingly popular due to the widespread use of the internet-based shopping and banking.
Credit cards remain the most common forms of payment for e-commerce transactions. As of 2008, in North America, almost 90% of online retail transactions were made with this payment type. It is difficult for an online retailer to operate without supporting credit and debit cards due to their widespread use. Online merchants must comply with stringent rules stipulated by the credit and debit card issuers (e.g. Visa and Mastercard) in accordance with a bank and financial regulation in the countries where the debit/credit service conducts business.
E-commerce payment system often use B2B mode. The security of customer information, business information, and payment information base is a concern during the payment process of transactions under the conventional B2B e-commerce model.
For the vast majority of payment systems accessible on the public Internet, baseline authentication (of the financial institution on the receiving end), data integrity, and confidentiality of the electronic information exchanged over the public network involves obtaining a certificate from an authorized certificate authority (CA) who provides public-key infrastructure (PKI). Even with transport layer security (TLS) in place to safeguard the portion of the transaction conducted over public networks—especially with payment systems—the customer-facing website itself must be coded with great care, so as not to leak credentials and expose customers to subsequent identity theft.
Despite widespread use in North America, there are still many countries such as China and India that have some problems to overcome in regard to credit card security. Increased security measures i
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https://en.wikipedia.org/wiki/Theban%20alphabet
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The Theban alphabet, also known as the witches' alphabet, is a writing system, specifically a substitution cipher of the Latin script, that was used by early modern occultists and is popular in the Wicca movement.
Publication history
It was first published in Johannes Trithemius's Polygraphia (1518) in which it was attributed to Honorius of Thebes "as Pietro d'Abano testifies in his greater fourth book". However, it is not known to be extant in any of the known writings attributed to D'Abano (1250–1316). Trithemius' student Heinrich Cornelius Agrippa (1486–1535) included it in his De Occulta Philosophia (Book III, chap. 29, 1533). It is also not known to be found in any manuscripts of the writings of Honorius of Thebes (e.g. Liber Iuratus Honorii, translated as The Sworn Book of Honorius), with the exception of the composite manuscript found in London, British Library Manuscript Sloane 3853, which however openly identifies Agrippa as its source.
Uses and correlations
It is also known as the Honorian alphabet or the Runes of Honorius after the legendary magus (though Theban is dissimilar to the Germanic runic alphabet), or the witches' alphabet due to its use in modern Wicca and other forms of witchcraft as one of many substitution ciphers to hide magical writings such as the contents of a Book of Shadows from prying eyes. The Theban alphabet has not been found in any publications prior to that of Trithemius, and bears little visual resemblance to most other alphabets.
There is one-to-one correspondence between Theban and the letters in the old Latin alphabet. The modern characters J and U are not represented. They are often transliterated using the Theban characters for I and V, respectively. In the original chart by Trithemius, the letter W comes after Z, as it was a recent addition to the Latin alphabet, and did not yet have a standard position. This caused it to be misinterpreted as an ampersand or end-of-sentence mark by later translators and copyists, such
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https://en.wikipedia.org/wiki/Xavier%20Leroy
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Xavier Leroy (born 15 March 1968) is a French computer scientist and programmer. He is best known for his role as a primary developer of the OCaml system. He is
Professor of software science at Collège de France. Before his appointment at Collège de France in 2018, he was senior scientist (directeur de recherche) at the French government research institution Inria.
Leroy was admitted to the École normale supérieure in Paris in 1987, where he studied mathematics and computer science. From 1989 to 1992 he did his PhD in computer science under the supervision of Gérard Huet.
He is an internationally recognized expert on functional programming languages and compilers. In recent years, he has taken an interest in formal methods, formal proofs and certified compilation. He is the leader of the CompCert project that develops an optimizing compiler for C (programming language), formally verified in Coq.
Leroy was also the original author of LinuxThreads, the most widely used threading package for Linux versions prior to 2.6. Linux 2.6 introduced NPTL, with much more extensive support from the kernel, to replace LinuxThreads.
In 2015 he was named a fellow of the Association for Computing Machinery "for contributions to safe, high-performance functional programming languages and compilers, and to compiler verification." He was awarded the 2016 Milner Award by the Royal Society, the 2021 ACM Software System Award, and the 2022 ACM SIGPLAN Programming Languages Achievement Award.
References
External links
Xavier Leroy's home page
1968 births
École Normale Supérieure alumni
Computer programmers
French computer scientists
Programming language researchers
Living people
Programming language designers
Fellows of the Association for Computing Machinery
Academic staff of the Collège de France
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https://en.wikipedia.org/wiki/Trimethylglycine
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Trimethylglycine is an amino acid derivative that occurs in plants. Trimethylglycine was the first betaine discovered; originally it was simply called betaine because, in the 19th century, it was discovered in sugar beets (Beta vulgaris subsp. vulgaris).
Medical uses
Betaine, sold under the brand name Cystadane among others, is indicated for the adjunctive treatment of homocystinuria, involving deficiencies or defects in cystathionine beta-synthase (CBS), 5,10-methylene-tetrahydrofolate reductase (MTHFR), or cobalamin cofactor metabolism (cbl).
The most common side effect is elevated levels of methionine in the blood.
Structure and reactions
Trimethylglycine is an N-methylated amino acid. It is a zwitterion as the molecule contains both a quaternary ammonium group and a carboxyl group. The carboxyl group will be partially protonated in aqueous solution below pH 4, that is, approximately below pH equal to (pKa + 2).
(aq) + (aq)
Demethylation of trimethylglycine gives dimethylglycine.
Production and biochemical processes
Processing sucrose from sugar beets yields glycine betaine as a byproduct. The economic value of the trimethylglycine rivals that of the sugar content in sugar beets.
Biosynthesis
In most organisms, glycine betaine is biosynthesized by oxidation of choline in two steps. The intermediate, betaine aldehyde, is generated by the action of the enzyme mitochondrial choline oxidase (choline dehydrogenase, EC 1.1.99.1). Betaine aldehyde is further oxidised in the mitochondria in mice to betaine by the enzyme betaine-aldehyde dehydrogenase (EC 1.2.1.8). In humans betaine aldehyde activity is performed by a nonspecific cystosolic aldehyde dehydrogenase enzyme (EC 1.2.1.3)
Biological function
Trimethylglycine is an organic osmolyte. Sugar beet was cultivated from sea beet, which requires osmolytes in order to survive in the salty soils of coastal areas. Trimethylglycine also occurs in high concentrations (~10 mM) in many marine invertebrates, su
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https://en.wikipedia.org/wiki/L%C3%A1szl%C3%B3%20Lov%C3%A1sz
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László Lovász (; born March 9, 1948) is a Hungarian mathematician and professor emeritus at Eötvös Loránd University, best known for his work in combinatorics, for which he was awarded the 2021 Abel Prize jointly with Avi Wigderson. He was the president of the International Mathematical Union from 2007 to 2010 and the president of the Hungarian Academy of Sciences from 2014 to 2020.
In graph theory, Lovász's notable contributions include the proofs of Kneser's conjecture and the Lovász local lemma, as well as the formulation of the Erdős–Faber–Lovász conjecture. He is also one of the eponymous authors of the LLL lattice reduction algorithm.
Early life and education
Lovász was born on March 9, 1948, in Budapest, Hungary.
Lovász attended the Fazekas Mihály Gimnázium in Budapest. He won three gold medals (1964–1966) and one silver medal (1963) at the International Mathematical Olympiad. He also participated in a Hungarian game show about math prodigies. Paul Erdős helped introduce Lovász to graph theory at a young age.
Lovász received his Candidate of Sciences (C.Sc.) degree in 1970 at the Hungarian Academy of Sciences. His advisor was Tibor Gallai. He received his first doctorate (Dr.Rer.Nat.) degree from Eötvös Loránd University in 1971 and his second doctorate (Dr.Math.Sci.) from the Hungarian Academy of Sciences in 1977.
Career
From 1971 to 1975, Lovász worked at Eötvös Loránd University as a research associate. From 1975 to 1978, he was a docent at the University of Szeged, and then served as a professor and the Chair of Geometry there until 1982. He then returned to Eötvös Loránd University as a professor and the Chair of Computer Science until 1993.
Lovász was a professor at Yale University from 1993 to 1999, when he moved to the Microsoft Research Center where he worked as a senior researcher until 2006. He returned to Eötvös Loránd University where he was the director of the Mathematical Institute (2006–2011) and a professor in the Department of Compute
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https://en.wikipedia.org/wiki/BBN%20Butterfly
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The BBN Butterfly was a massively parallel computer built by Bolt, Beranek and Newman in the 1980s. It was named for the "butterfly" multi-stage switching network around which it was built. Each machine had up to 512 CPUs, each with local memory, which could be connected to allow every CPU access to every other CPU's memory, although with a substantially greater latency (roughly 15:1) than for its own. The CPUs were commodity microprocessors. The memory address space was shared.
The first generation used Motorola 68000 processors, followed by a 68010 version.
The Butterfly connect was developed specifically for this computer. The second or third generation, GP-1000 models used Motorola 68020's and scaled to 256 CPUs. The later, TC-2000 models used Motorola MC88100's, and scaled to 512 CPUs.
The Butterfly was initially developed as the Voice Funnel, a router for the ST-II protocol intended for carrying voice and video over IP networks. The Butterfly hardware was later used for the Butterfly Satellite IMP (BSAT) packet switch of DARPA's Wideband Packet Satellite Network which operated at multiple sites around the US over a shared 3 Mbit/s broadcast satellite channel. In the late 1980s, this network became the Terrestrial Wideband Network, based on terrestrial T1 circuits instead of a shared broadcast satellite channel and the BSAT became the Wideband Packet Switch (WPS). Another DARPA sponsored project at BBN produced the Butterfly Multiprocessor Internet Gateway (Internet Router) to interconnect different types of networks at the IP layer. Like the BSAT, the Butterfly Gateway broke the contention of a shared bus minicomputer architecture that had been in use for Internet Gateways by combining the routing computations and I/O at the network interfaces and using the Butterfly's switch fabric to provide the network interconnections. This resulted in significantly higher link throughputs.
The Butterfly began with a proprietary operating system called Chrysalis,
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https://en.wikipedia.org/wiki/Intermediate%20power%20amplifier
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An Intermediate power amplifier (IPA) is one stage of the amplification process in a radio transmitter which usually occurs prior to the final high power amplification. The IPA provides lower power RF energy necessary to drive the final. In very high power transmitters, such as 10 kilowatts and above, multiple IPAs are combined to provide enough drive for the final.
An exciter, an even lower power transmitter, provides a similar service to the IPA by driving it; although an exciter usually encompasses other important functions, such as choosing the frequency of the RF.
References
Electronic amplifiers
Broadcast engineering
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https://en.wikipedia.org/wiki/Voltage%20doubler
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A voltage doubler is an electronic circuit which charges capacitors from the input voltage and switches these charges in such a way that, in the ideal case, exactly twice the voltage is produced at the output as at its input.
The simplest of these circuits is a form of rectifier which take an AC voltage as input and outputs a doubled DC voltage. The switching elements are simple diodes and they are driven to switch state merely by the alternating voltage of the input. DC-to-DC voltage doublers cannot switch in this way and require a driving circuit to control the switching. They frequently also require a switching element that can be controlled directly, such as a transistor, rather than relying on the voltage across the switch as in the simple AC-to-DC case.
Voltage doublers are a variety of voltage multiplier circuits. Many, but not all, voltage doubler circuits can be viewed as a single stage of a higher order multiplier: cascading identical stages together achieves a greater voltage multiplication.
Voltage doubling rectifiers
Villard circuit
The Villard circuit, conceived by Paul Ulrich Villard, consists simply of a capacitor and a diode. While it has the great benefit of simplicity, its output has very poor ripple characteristics. Essentially, the circuit is a diode clamp circuit. The capacitor is charged on the negative half cycles to the peak AC voltage (Vpk). The output is the superposition of the input AC waveform and the steady DC of the capacitor. The effect of the circuit is to shift the DC value of the waveform. The negative peaks of the AC waveform are "clamped" to 0 V (actually −VF, the small forward bias voltage of the diode) by the diode, therefore the positive peaks of the output waveform are 2Vpk. The peak-to-peak ripple is an enormous 2Vpk and cannot be smoothed unless the circuit is effectively turned into one of the more sophisticated forms. This is the circuit (with diode reversed) used to supply the negative high voltage for the
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https://en.wikipedia.org/wiki/Betts%20electrolytic%20process
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The Betts electrolytic process is an industrial process for purification of lead from bullion. Lead obtained from its ores is impure because lead is a good solvent for many metals. Often these impurities are tolerated, but the Betts electrolytic process is used when high purity lead is required, especially for bismuth-free lead.
Process description for lead
The electrolyte for this process is a mixture of lead fluorosilicate ("PbSiF6") and hexafluorosilicic acid (H2SiF6) operating at 45 °C (113 °F). Cathodes are thin sheets of pure lead and anodes are cast from the impure lead to be purified. A potential of 0.5 volts is applied. At the anode, lead dissolves, as do metal impurities that are less noble than lead. Impurities that are more noble than lead, such as silver, gold, and bismuth, flake from the anode as it dissolves and settle to the bottom of the vessel as "anode mud." Pure metallic lead plates onto the cathode, with the less noble metals remaining in solution. Because of its high cost, electrolysis is used only when very pure lead is needed. Otherwise pyrometallurgical methods are preferred, such as the Parkes process followed by the Betterton-Kroll process.
History
The process is named for its inventor Anson Gardner Betts who filed several patents for this method starting in 1901.
See also
Processing lead from ore
Lead smelter
Electrochemical engineering
References
External links
Bismuth
Bismuth
Lead
Electrolysis
Metallurgical processes
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https://en.wikipedia.org/wiki/List%20of%20United%20States%20regional%20mathematics%20competitions
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Many math competitions in the United States have regional restrictions. Of these, most are statewide.
For a more complete list, please visit here .
The contests include:
Alabama
Alabama Statewide High School Mathematics Contest
Virgil Grissom High School Math Tournament
Vestavia Hills High School Math Tournament
Arizona
Great Plains Math League
AATM State High School Contest
California
Bay Area Math Olympiad
Lawrence Livermore National Laboratories Annual High School Math Challenge
Cal Poly Math Contest and Trimathlon
Polya Competition
Bay Area Math Meet
College of Creative Studies Math Competition
LA Math Cup
Math Day at the Beach hosted by CSULB
Math Field Day for San Diego Middle Schools
Mesa Day Math Contest at UC Berkeley
Santa Barbara County Math Superbowl
Pomona College Mathematical Talent Search
Redwood Empire Mathematics Tournament hosted by Humboldt State (middle and high school)
San Diego Math League and San Diego Math Olympiad hosted by the San Diego Math Circle
Santa Clara University High School Mathematics Contest
SC Mathematics Competition (SCMC) hosted by RSO@USC
Stanford Mathematics Tournament
UCSD/GSDMC High School Honors Mathematics Contest
Colorado
Colorado Mathematics Olympiad
District of Columbia
Moody's Mega Math
Florida
Florida-Stuyvesant Alumni Mathematics Competition
David Essner Mathematics Competition
James S. Rickards High School Fall Invitational
FAMAT Regional Competitions:
January Regional
February Regional
March Regional
FGCU Math Competition
Georgia
Central Math Meet(grades 9 - 12)
GA Council of Teachers of Mathematics State Varsity Math Tournament
STEM Olympiads Of America Math, Science & Cyber Olympiads (grades 3 - 8)
Valdosta State University Middle Grades Mathematics Competition
Illinois
ICTM math contest (grades 3–12)
Indiana
[IUPUI High School Math Contest] (grades 9–12)
Huntington University Math Competition (grades 6–12)
Indiana Math League
IASP Academic Super Bowl
Rose-Hulman H
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https://en.wikipedia.org/wiki/LGP-30
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The LGP-30, standing for Librascope General Purpose and then Librascope General Precision, is an early off-the-shelf computer. It was manufactured by the Librascope company of Glendale, California (a division of General Precision Inc.), and sold and serviced by the Royal Precision Electronic Computer Company, a joint venture with the Royal McBee division of the Royal Typewriter Company. The LGP-30 was first manufactured in 1956, at a retail price of $47,000, .
The LGP-30 was commonly referred to as a desk computer. Its height, width, and depth, excluding the typewriter shelf, was . It weighed about , and was mounted on sturdy casters which facilitated moving the unit.
Design
The primary design consultant for the Librascope computer was Stan Frankel, a Manhattan Project veteran and one of the first programmers of ENIAC. He designed a usable computer with a minimal amount of hardware. The single address instruction set had only 16 commands. Magnetic drum memory held the main memory, and the central processing unit (CPU) processor registers, timing information, and the master bit clock, each on a dedicated track. The number of vacuum tubes was minimized by using solid-state diode logic, a bit-serial architecture and multiple use of each of the 15 flip-flops.
It was a binary, 31-bit word computer with a 4096-word drum memory. Standard inputs were the Flexowriter keyboard and paper tape (ten six-bit characters/second). The standard output was the Flexowriter printer (typewriter, working at 10 characters/second). An optional higher-speed paper tape reader and punch was available as a separate peripheral.
The computer contained 113 electronic tubes and 1450 diodes. The tubes were mounted on 34 etched circuit pluggable cards which also contain associated components. The 34 cards were of only 12 different types. Card-extenders were available to permit dynamic testing of all machine functions. 680 of the 1450 diodes were mounted on one pluggable logic board.
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https://en.wikipedia.org/wiki/Novum%20Organum
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The Novum Organum, fully Novum Organum, sive Indicia Vera de Interpretatione Naturae ("New organon, or true directions concerning the interpretation of nature") or Instaurationis Magnae, Pars II ("Part II of The Great Instauration"), is a philosophical work by Francis Bacon, written in Latin and published in 1620. The title is a reference to Aristotle's work Organon, which was his treatise on logic and syllogism. In Novum Organum, Bacon details a new system of logic he believes to be superior to the old ways of syllogism. This is now known as the Baconian method.
For Bacon, finding the essence of a thing was a simple process of reduction, and the use of inductive reasoning. In finding the cause of a 'phenomenal nature' such as heat, one must list all of the situations where heat is found. Then another list should be drawn up, listing situations that are similar to those of the first list except for the lack of heat. A third table lists situations where heat can vary. The 'form nature', or cause, of heat must be that which is common to all instances in the first table, is lacking from all instances of the second table and varies by degree in instances of the third table.
The title page of Novum Organum depicts a galleon passing between the mythical Pillars of Hercules that stand either side of the Strait of Gibraltar, marking the exit from the well-charted waters of the Mediterranean into the Atlantic Ocean. The Pillars, as the boundary of the Mediterranean, have been smashed through by Iberian sailors, opening a new world for exploration. Bacon hopes that empirical investigation will, similarly, smash the old scientific ideas and lead to greater understanding of the world and heavens. This title page was liberally copied from Andrés García de Céspedes's Regimiento de Navegación, published in 1606.
The Latin tag across the bottom – Multi pertransibunt & augebitur scientia – is taken from the Old Testament (Daniel 12:4). It means: "Many will travel and knowledge wi
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https://en.wikipedia.org/wiki/IC%20power-supply%20pin
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IC power-supply pins denote a voltage and current supply terminals in electric, electronics engineering, and in Integrated circuit design. Integrated circuits (ICs) have at least two pins that connect to the power rails of the circuit in which they are installed. These are known as the power-supply pins. However, the labeling of the pins varies by IC family and manufacturer. The double subscript notation usually corresponds to a first letter in a given IC family (transistors) notation of the terminals (e.g. VDD supply for a drain terminal in FETs etc.).
The simplest labels are V+ and V−, but internal design and historical traditions have led to a variety of other labels being used. V+ and V− may also refer to the non-inverting (+) and inverting (−) voltage inputs of ICs like op amps.
For power supplies, sometimes one of the supply rails is referred to as ground (abbreviated "GND") positive and negative voltages are relative to the ground. In digital electronics, negative voltages are seldom present, and the ground nearly always is the lowest voltage level. In analog electronics (e.g. an audio power amplifier) the ground can be a voltage level between the most positive and most negative voltage level.
While double subscript notation, where subscripted letters denote the difference between two points, uses similar-looking placeholders with subscripts, the double-letter supply voltage subscript notation is not directly linked (though it may have been an influencing factor).
BJTs
ICs using bipolar junction transistors have VCC (+, positive) and VEE (-, negative) power-supply pins though VCC is also often used for CMOS devices as well.
In circuit diagrams and circuit analysis, there are long-standing conventions regarding the naming of voltages, currents, and some components. In the analysis of a bipolar junction transistor, for example, in a common-emitter configuration, the DC voltage at the collector, emitter, and base (with respect to ground) may be written
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https://en.wikipedia.org/wiki/Van%20Arkel%E2%80%93de%20Boer%20process
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The van Arkel–de Boer process, also known as the iodide process or crystal-bar process, was the first industrial process for the commercial production of pure ductile titanium, zirconium and some other metals. It was developed by Anton Eduard van Arkel and Jan Hendrik de Boer in 1925. Now it is used in the production of small quantities of ultrapure titanium and zirconium. It primarily involves the formation of the metal iodides and their subsequent decomposition to yield pure metal.
This process was superseded commercially by the Kroll process.
Process
As seen in the diagram below, impure titanium, zirconium, hafnium, vanadium, thorium or protactinium is heated in an evacuated vessel with a halogen at 50–250 °C. The patent specifically involved the intermediacy of TiI4 and ZrI4, which were volatilized (leaving impurities as solid). At atmospheric pressure TiI4 melts at 150 °C and boils at 377 °C, while ZrI4 melts at 499 °C and boils at 600 °C. The boiling points are lower at reduced pressure. The gaseous metal tetraiodide is decomposed on a white hot tungsten filament (1400 °C). As more metal is deposited the filament conducts better and thus a greater electric current is required to maintain the temperature of the filament. The process can be performed in the span of several hours or several weeks, depending on the particular setup.
Generally, the crystal bar process can be performed using any number of metals using whichever halogen or combination of halogens is most appropriate for that sort of transport mechanism, based on the reactivities involved. The only metals it has been used to purify on an industrial scale are titanium, zirconium and hafnium, and in fact is still in use today on a much smaller scale for special purity needs.
References
Industrial processes
Zirconium
Dutch inventions
Methods of crystal growth
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https://en.wikipedia.org/wiki/List%20of%20transmission%20sites
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In the following there are lists of sites of notable radio transmitters. During the early history of radio many countries had only a few high power radio stations, operated either by the government or large corporations, which broadcast to the population or to other countries. Because of the large number of transmission sites, this list is not complete. Outside of Europe senders and repeater stations are emphatically presented from international services.
Legend
Europe
Austria
Belarus
Molodecno (VLF)
Belgium
Schoten (FM, TV)
Wavre (MW, SW, dismantled) FM DAB TV)
Overijse (MW closed)
Bosnia and Herzegovina
Mostre transmitter (MW)
Bulgaria
Kaliakra (MW, dismantled)
Vakarel (LW, MW, dismantled)
Croatia
Grbre transmitter (MW)
Deanovec transmitter (MW, KW)
Czech Republic
Liblice (dismantled)
Liblice (MW, on air with low power again)
Topolná (LW dismantled)
Mělník-Chloumek (MW closed)
Dobrochov (MW closed)
Jested (FM)
Denmark
Kalundborg (LW, MW (dismantled))
Finland
Lahti (LW, SW, shut down)
Pori transmitter (LW, SW shut down)
Pasilan linkkitorni (DVB-T)
Anjalankoski Radio and TV-Mast (FM, DVB-T)
Eurajoki TV Mast (DVB-T)
FM- and TV-mast Helsinki-Espoo (FM, DVB-T)
Haapavesi TV Mast (DVB-T)
Hollola TV Mast (DVB-T)
Kuopio Radio and TV Mast (FM, DVB-T)
Lapua Radio and TV-Mast (FM, DVB-T)
Oulu TV Mast (DVB-T)
Pihtipudas TV Mast (DVB-T)
Smedsböle Radio Mast (FM)
Teisko TV-mast (DVB-T)
Tervola Radio and TV-Mast (FM, DVB-T)
Turku radio and television station (FM, DVB-T)
Jyväskylä TV-mast (DVB-T)
France
Allouis (LW, SW)
Le Blanc (VLF)
Issoudun (SW)
Paris-Eiffel Tower (FM, TV)
Lyon-Metallic tower of Fourvière (FM, TV)
Sélestat (MW shut down)
HWU transmitter (LW, SW)
Col de la Madone transmitter (LW, SW)
Lafayette transmitter (VLF)
Limeux transmitting station (FM, TV)
TV Mast Niort-Maisonnay (TV)
Transmitter Le Mans-Mayet (FM, TV)
Realtor transmitter (MW, partially dismantled)
Sud Radio Transmitter Pic Blanc (MW, partially dismantled)
Pic de Nore transmitter (FM, TV)
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https://en.wikipedia.org/wiki/MSAV
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Microsoft Anti-Virus (MSAV) is an antivirus program introduced by Microsoft for its MS-DOS operating system. The program first appeared in MS-DOS version 6.0 (1993)
and last appeared in MS-DOS 6.22. The first version of the antivirus program was basic, had no inbuilt update facility (updates had to be obtained from a BBS and manually installed by the user) and could scan for 1,234 different viruses. Microsoft Anti-Virus for Windows (MWAV), included as part of the package, was a front end that allowed MSAV to run properly on Windows 3.1x.
In 2009, Microsoft launched an in-house antivirus solution named Microsoft Security Essentials, which later was phased out in favor of Microsoft Defender.
History
Microsoft Anti-Virus was supplied by Central Point Software Inc. (later acquired by Symantec in 1994 and integrated into Symantec's Norton AntiVirus product) and was a stripped-down version of the Central Point Anti-Virus (CPAV) product which Central Point Software Inc., had licensed from Carmel Software Engineering in Haifa, Israel. Carmel Software sold the product as Turbo Anti-Virus both domestically and abroad.
Microsoft Anti-Virus for Windows was also provided by Central Point Software.
Features
MSAV featured the "Detect and Clean" strategy and the detection of boot sector and Trojan horse-type viruses (which were typical virus problems at that time).
The program also had an anti-stealth and check sum feature that could be used to detect any changes in normal files. This technology was intended to make up for the unavailability of regular update packages. The final update of MSAV was released in June 1996 by Symantec. The update added the ability to detect polymorphic viruses and the virus definitions were updated to scan for a total of 2,371 viruses.
VSafe TSR
VSafe is a terminate and stay resident component of MSAV that provided real-time virus protection.
By default, VSafe does the following:
Checks executable files for viruses (on execution).
Checks a
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https://en.wikipedia.org/wiki/CAP%20computer
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The Cambridge CAP computer was the first successful experimental computer that demonstrated the use of security capabilities, both in hardware and software. It was developed at the University of Cambridge Computer Laboratory in the 1970s. Unlike most research machines of the time, it was also a useful service machine.
The sign currently on the front of the machine reads:
The CAP project on memory protection ran from 1970 to 1977. It was based on capabilities implemented in hardware, under M. Wilkes and R. Needham with D. Wheeler responsible for the implementation. R. Needham was awarded a BCS Technical Award in 1978 for the CAP (Capability Protection) Project.
Design
The CAP was designed such that any access to a memory segment or hardware required that the current process held the necessary capabilities.
The 32-bit processor featured microprogramming control, two 256-entry caches, a 32-entry write buffer and the capability unit itself, which had 64 registers for holding evaluated capabilities. Floating point operations were available using a single 72-bit accumulator. The instruction set featured over 200 instructions, including basic ALU and memory operations, to capability- and process-control instructions.
Instead of the programmer-visible registers used in Chicago and Plessey System 250 designs, the CAP would load internal registers silently when a program defined a capability. The memory was divided into segments of up to 64K 32-bit words. Each segment could contain data or capabilities, but not both. Hardware was accessed via an associated minicomputer.
All procedures constituting the operating system were written in ALGOL 68C, although a number of other closely associated protected procedures - such as a paginator - are written in BCPL.
Operation
The CAP first became operational in 1976. A fully functional computer, it featured a complete operating system, file system, compilers, and so on. The OS used a process tree structure, with an initial process
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https://en.wikipedia.org/wiki/Gromatici
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Gromatici (from Latin groma or gruma, a surveyor's pole) or agrimensores was the name for land surveyors amongst the ancient Romans. The "gromatic writers" were technical writers who codified their techniques of surveying, most of whose preserved writings are found in the Corpus Agrimensorum Romanorum.
History
Roman Republic
At the foundation of a colony and the assignation of lands the auspices were taken, for which purpose the presence of the augur was necessary. But the business of the augur did not extend beyond the religious part of the ceremony: the division and measurement of the land were made by professional measurers. These were the finitores mentioned by the early writers, who in the later periods were called mensores and agrimensores. The business of a finitor could only be done by a free man, and the honourable nature of his office is indicated by the rule that there was no bargain for his services, but he received his pay in the form of a gift. These finitores appear also to have acted as judices, under the name of arbitri (single arbiter), in those disputes about boundaries which were purely of a technical, not a legal, character. The first professional surveyor mentioned is Lucius Decidius Saxa, who was employed by Mark Antony in the measurement of camps.
Roman Empire
Under the empire the observance of the auspices in the fixing of camps and the establishment of military colonies was less regarded, and the practice of the agrimensores was greatly increased. The distribution of land amongst the veterans, the increase in the number of military colonies, the settlement of Italian peasants in the provinces, the general survey of the empire under Augustus, the separation of private and state domains, led to the establishment of a recognized professional corporation of surveyors. The practice was also codified as a system by technical writers such as Julius Frontinus, Hyginus, Siculus Flaccus, and other Gromatic writers, as they are sometimes te
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https://en.wikipedia.org/wiki/Intel%208253
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The Intel 8253 and 8254 are programmable interval timers (PITs), which perform timing and counting functions using three 16-bit counters.
The 825x family was primarily designed for the Intel 8080/8085-processors, but were later used in x86 compatible systems. The 825x chips, or an equivalent circuit embedded in a larger chip, are found in all IBM PC compatibles and Soviet computers like the Vector-06C.
In PC compatibles, Timer Channel 0 is assigned to IRQ-0 (the highest priority hardware interrupt). Timer Channel 1 is assigned to DRAM refresh (at least in early models before the 80386). Timer Channel 2 is assigned to the PC speaker.
The Intel 82c54 (c for CMOS logic) variant handles up to 10 MHz clock signals.
History
The 8253 is described in the 1980 Intel "Component Data Catalog" publication. The 8254, described as a superset of the 8253 with higher clock speed ratings, has a "preliminary" data sheet in the 1982 Intel "Component Data Catalog".
The 8254 is implemented in HMOS and has a "Read Back" command not available on the 8253, and permits reading and writing of the same counter to be interleaved.
Modern PC compatibles, either when using SoC CPUs or southbridge typically implement full 8254 compatibility for backward compatibility and interoperability. The Read Back command being a vital I/O feature for interoperability with multicore CPUs and GPUs.
Variants
There is military version of Intel M8253 with the temperature range of -55 °C to +125 °C which it also have ±10% 5V power tolerance. The available 82C53 CMOS version was outsourced to Oki Electronic Industry Co., Ltd. The available package version of Intel 82C54 was in 28-pin PLCC of sampling at first quarter of 1986.
Features
The timer has three counters, numbered 0 to 2. Each channel can be programmed to operate in one of six modes. Once programmed, the channels operate independently.
Each counter has two input pins – "CLK" (clock input) and "GATE" – and one pin, "OUT", for data output. The
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https://en.wikipedia.org/wiki/Financial%20econometrics
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Financial econometrics is the application of statistical methods to financial market data. Financial econometrics is a branch of financial economics, in the field of economics. Areas of study include capital markets, financial institutions, corporate finance and corporate governance. Topics often revolve around asset valuation of individual stocks, bonds, derivatives, currencies and other financial instruments.
It differs from other forms of econometrics because the emphasis is usually on analyzing the prices of financial assets traded at competitive, liquid markets.
People working in the finance industry or researching the finance sector often use econometric techniques in a range of activities – for example, in support of portfolio management and in the valuation of securities. Financial econometrics is essential for risk management when it is important to know how often 'bad' investment outcomes are expected to occur over future days, weeks, months and years.
Topics
The sort of topics that financial econometricians are typically familiar with include:
analysis of high-frequency price observations
arbitrage pricing theory
asset price dynamics
optimal asset allocation
cointegration
event study
nonlinear financial models such as autoregressive conditional heteroskedasticity
realized variance
fund performance analysis such as returns-based style analysis
tests of the random walk hypothesis
the capital asset pricing model
the term structure of interest rates (the yield curve)
value at risk
volatility estimation techniques such as exponential smoothing models and RiskMetrics
Research community
The Society for Financial Econometrics (SoFiE) is a global network of academics and practitioners dedicated to sharing research and ideas in the fast-growing field of financial econometrics. It is an independent non-profit membership organization, committed to promoting and expanding research and education by organizing and sponsoring conferences, programs
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https://en.wikipedia.org/wiki/Disposable%20email%20address
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Disposable email addressing, also known as DEA or dark mail or "masked" email, refers to an approach which involves a unique email address being used for every contact, entity, or for a limited number of times or uses. The benefit is that if anyone compromises the address or utilizes it in connection with email abuse, the address owner can easily cancel (or "dispose" of) it without affecting any of their other contacts.
Uses
Disposable email addressing sets up a different, unique email address for every sender/recipient combination. It operates most usefully in scenarios where someone may sell or release an email address to spam lists or to other unscrupulous entities. The most common situations of this type involve online registration for sites offering discussion groups, bulletin boards, chat rooms, online shopping, and file hosting services. At a time when email spam has become an everyday nuisance, and when identity theft threatens, DEAs can serve as a convenient tool for protecting Internet users.
Disposable email addresses can be cancelled if someone starts to use the address in a manner that was not intended by the creator. Examples are the accidental release of an email to a spam list, or if the address was procured by spammers. Alternatively, the user may simply decide not to receive further correspondence from the sender. Whatever the cause, DEA allows the address owner to take unilateral action by simply cancelling the address in question. Later, the owner can determine whether to update the recipient or not.
Disposable email addresses typically forward to one or more real email mailboxes in which the owner receives and reads messages. The contact with whom a DEA is shared never learns the real email address of the user. If a database manages the DEA, it can also quickly identify the expected sender of each message by retrieving the associated contact name of each unique DEA. Used properly, DEA can also help identify which recipients handle email addr
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https://en.wikipedia.org/wiki/Intel%20QuickPath%20Interconnect
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The Intel QuickPath Interconnect (QPI) is a point-to-point processor interconnect developed by Intel which replaced the front-side bus (FSB) in Xeon, Itanium, and certain desktop platforms starting in 2008. It increased the scalability and available bandwidth. Prior to the name's announcement, Intel referred to it as Common System Interface (CSI). Earlier incarnations were known as Yet Another Protocol (YAP) and YAP+.
QPI 1.1 is a significantly revamped version introduced with Sandy Bridge-EP (Romley platform).
QPI was replaced by Intel Ultra Path Interconnect (UPI) in Skylake-SP Xeon processors based on LGA 3647 socket.
Background
Although sometimes called a "bus", QPI is a point-to-point interconnect. It was designed to compete with HyperTransport that had been used by Advanced Micro Devices (AMD) since around 2003. Intel developed QPI at its Massachusetts Microprocessor Design Center (MMDC) by members of what had been the Alpha Development Group, which Intel had acquired from Compaq and HP and in turn originally came from Digital Equipment Corporation (DEC).
Its development had been reported as early as 2004.
Intel first delivered it for desktop processors in November 2008 on the Intel Core i7-9xx and X58 chipset.
It was released in Xeon processors code-named Nehalem in March 2009 and Itanium processors in February 2010 (code named Tukwila).
It was supplanted by the Intel Ultra Path Interconnect starting in 2017 on the Xeon Skylake-SP platforms.
Implementation
The QPI is an element of a system architecture that Intel calls the QuickPath architecture that implements what Intel calls QuickPath technology. In its simplest form on a single-processor motherboard, a single QPI is used to connect the processor to the IO Hub (e.g., to connect an Intel Core i7 to an X58). In more complex instances of the architecture, separate QPI link pairs connect one or more processors and one or more IO hubs or routing hubs in a network on the motherboard, allowing all of the
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https://en.wikipedia.org/wiki/Covad
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Covad Communications Company, also known as Covad Communications Group, was an American provider of broadband voice and data communications. By 2006, the company had 530,000 subscribers, and ranked as the 16th largest ISP in the United States. Covad was acquired by U.S. Venture Partners, who in 2010 announced a three-way merger of MegaPath, Covad, and Speakeasy, creating a single Managed Services Local Exchange Carrier (MSLEC), providing voice and internet services; the new company was named MegaPath.
In January 2015, telecommunications service provider Global Capacity acquired MegaPath's wholesale and direct access business, which included assets acquired from Covad.
The name Covad was derived from acronyms which have varied over time, including COmbined Voice And Data, Copper Over Voice And Data, and in its earliest form, COpper Value ADded.
History
Covad was the first service provider to offer a national DSL broadband service. In addition they offered Voice over IP, T1, Web hosting, managed security, IP and dial-up, and bundled voice and data services directly through Covad's network and through Internet Service Providers, value-added resellers, telecommunications carriers and affinity groups to businesses. Covad broadband services were available in 44 states, including 235 Metropolitan Statistical Areas (MSAs), a services area available to over 50 percent of all businesses. The company was founded in San Jose, CA.
By 2008, Covad added the Samsung Acemap DSLAM to their portfolio on top of their pre-existing Nokia D50 DSLAMs, to allow for ADSL2+ technology, which can reach DSL speeds up to 15 Mbit/s.
The launch of the AceMAP was primarily instigated to provide combined POTS and ADSL2+ service to Earthlink end users and were deployed in more residential areas instead of concentrating on business-centric markets.
Covad was acquired a by private equity firm, Platinum Equity, in April 2008. In 2010, it was sold to U.S. Venture Partners, which merged Covad, and
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https://en.wikipedia.org/wiki/Baker%27s%20map
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In dynamical systems theory, the baker's map is a chaotic map from the unit square into itself. It is named after a kneading operation that bakers apply to dough: the dough is cut in half, and the two halves are stacked on one another, and compressed.
The baker's map can be understood as the bilateral shift operator of a bi-infinite two-state lattice model. The baker's map is topologically conjugate to the horseshoe map. In physics, a chain of coupled baker's maps can be used to model deterministic diffusion.
As with many deterministic dynamical systems, the baker's map is studied by its action on the space of functions defined on the unit square. The baker's map defines an operator on the space of functions, known as the transfer operator of the map. The baker's map is an exactly solvable model of deterministic chaos, in that the eigenfunctions and eigenvalues of the transfer operator can be explicitly determined.
Formal definition
There are two alternative definitions of the baker's map which are in common use. One definition folds over or rotates one of the sliced halves before joining it (similar to the horseshoe map) and the other does not.
The folded baker's map acts on the unit square as
When the upper section is not folded over, the map may be written as
The folded baker's map is a two-dimensional analog of the tent map
while the unfolded map is analogous to the Bernoulli map. Both maps are topologically conjugate. The Bernoulli map can be understood as the map that progressively lops digits off the dyadic expansion of x. Unlike the tent map, the baker's map is invertible.
Properties
The baker's map preserves the two-dimensional Lebesgue measure.
The map is strong mixing and it is topologically mixing.
The transfer operator maps functions on the unit square to other functions on the unit square; it is given by
The transfer operator is unitary on the Hilbert space of square-integrable functions on the unit square. The spectrum is continuous, a
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https://en.wikipedia.org/wiki/Synchronous%20circuit
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In digital electronics, a synchronous circuit is a digital circuit in which the changes in the state of memory elements are synchronized by a clock signal. In a sequential digital logic circuit, data are stored in memory devices called flip-flops or latches. The output of a flip-flop is constant until a pulse is applied to its "clock" input, upon which the input of the flip-flop is latched into its output. In a synchronous logic circuit, an electronic oscillator called the clock generates a string (sequence) of pulses, the "clock signal". This clock signal is applied to every storage element, so in an ideal synchronous circuit, every change in the logical levels of its storage components is simultaneous. Ideally, the input to each storage element has reached its final value before the next clock occurs, so the behaviour of the whole circuit can be predicted exactly. Practically, some delay is required for each logical operation, resulting in a maximum speed limitations at which each synchronous system can run.
To make these circuits work correctly, a great deal of care is needed in the design of the clock distribution networks. Static timing analysis is often used to determine the maximum safe operating speed.
Nearly all digital circuits, and in particular nearly all CPUs, are fully synchronous circuits with a global clock.
Exceptions are often compared to fully synchronous circuits.
Exceptions include self-synchronous circuits,
globally asynchronous locally synchronous circuits,
and fully asynchronous circuits.
See also
Synchronous network
Asynchronous circuit
Moore machine
Mealy machine
Finite state machine
Sequential logic
Memory
Control unit
Arithmetic logic unit
Processor register
Application-specific integrated circuit (ASIC)
References
Automata (computation)
Clock signal
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https://en.wikipedia.org/wiki/Asynchronous%20circuit
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Asynchronous circuit (clockless or self-timed circuit) is a sequential digital logic circuit that does not use a global clock circuit or signal generator to synchronize its components. Instead, the components are driven by a handshaking circuit which indicates a completion of a set of instructions. Handshaking works by simple data transfer protocols. Many synchronous circuits were developed in early 1950s as part of bigger asynchronous systems (e.g. ORDVAC). Asynchronous circuits and theory surrounding is a part of several steps in integrated circuit design, a field of digital electronics engineering.
Asynchronous circuits are contrasted with synchronous circuits, in which changes to the signal values in the circuit are triggered by repetitive pulses called a clock signal. Most digital devices today use synchronous circuits. However asynchronous circuits have a potential to be much faster, have a lower level of power consumption, electromagnetic interference, and better modularity in large systems. Asynchronous circuits are an active area of research in digital logic design.
It was not until the 1990s when viability of the asynchronous circuits was shown by real-life commercial products.
Overview
All digital logic circuits can be divided into combinational logic, in which the output signals depend only on the current input signals, and sequential logic, in which the output depends both on current input and on past inputs. In other words, sequential logic is combinational logic with memory. Virtually all practical digital devices require sequential logic. Sequential logic can be divided into two types, synchronous logic and asynchronous logic.
Synchronous circuits
In synchronous logic circuits, an electronic oscillator generates a repetitive series of equally spaced pulses called the clock signal. The clock signal is supplied to all the components of the IC. Flip-flops only flip when triggered by the edge of the clock pulse, so changes to the logic signals thr
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https://en.wikipedia.org/wiki/Linux%20for%20PlayStation%202
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Linux for PlayStation 2 (or PS2 Linux) is a kit released by Sony Computer Entertainment in 2002 that allows the PlayStation 2 console to be used as a personal computer. It included a Linux-based operating system, a USB keyboard and mouse, a VGA adapter, a PS2 network adapter (Ethernet only), and a 40 GB hard disk drive (HDD). An 8 MB memory card is required; it must be formatted during installation, erasing all data previously saved on it, though afterwards the remaining space may be used for savegames. It is strongly recommended that a user of Linux for PlayStation 2 have some basic knowledge of Linux before installing and using it, due to the command-line interface for installation.
The official site for the project was closed at the end of October 2009 and communities like ps2dev are no longer active.
Capabilities
The Linux Kit turns the PlayStation 2 into a full-fledged computer system, but it does not allow for use of the DVD-ROM drive except to read PS1 and PS2 discs due to piracy concerns by Sony. Although the HDD included with the Linux Kit is not compatible with PlayStation 2 games, reformatting the HDD with the utility disc provided with the retail HDD enables use with PlayStation 2 games but erases PS2 Linux, though there is a driver that allows PS2 Linux to operate once copied onto the APA partition created by the utility disc. The Network Adapter included with the kit only supports Ethernet; a driver is available to enable modem support if the retail Network Adapter (which includes a built-in V.90 modem) is used. The kit supports display on RGB monitors (with sync-on-green) using a VGA cable provided with the Linux Kit, or television sets with the normal cable included with the PlayStation 2 unit.
The PS2 Linux distribution is based on , a Japanese distribution itself based on Red Hat Linux. PS2 Linux is similar to Red Hat Linux 6, and has most of the features one might expect in a Red Hat Linux 6 system. The stock kernel is Linux 2.2.1 (although
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https://en.wikipedia.org/wiki/Adaptationism
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Adaptationism (also known as functionalism) is the Darwinian view that many physical and psychological traits of organisms are evolved adaptations. Pan-adaptationism is the strong form of this, deriving from the early 20th century modern synthesis, that all traits are adaptations, a view now shared by only a few biologists.
The "adaptationist program" was heavily criticized by Stephen Jay Gould and Richard Lewontin in their 1979 paper "The Spandrels of San Marco and the Panglossian Paradigm". According to Gould and Lewontin, evolutionary biologists had a habit of proposing adaptive explanations for any trait by default without considering non-adaptive alternatives, and often by conflating products of adaptation with the process of natural selection. One formal alternative to adaptationist explanations for traits in organisms is the neutral theory of molecular evolution, which proposes that features in organisms can arise through neutral transitions and become fixed in a population by chance (genetic drift). Constructive neutral evolution (CNE) is another paradigm which proposes a means by which complex systems emerge through neutral transitions, and CNE has been used to help understand the origins of a wide variety of features from the spliceosome of eukaryotes to the interdependency and simplification widespread in microbial communities. For many, neutral evolution is seen as the null hypothesis when attempting to explain the origins of a complex trait, so that adaptive scenarios for the origins of traits undergo a more rigorous demonstration prior to their acceptance.
Introduction
Criteria to identify a trait as an adaptation
Adaptationism is an approach to studying the evolution of form and function. It attempts to frame the existence and persistence of traits, assuming that each of them arose independently and improved the reproductive success of the organism's ancestors.
A trait is an adaptation if it fulfils the following criteria:
The trait is a variat
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https://en.wikipedia.org/wiki/Crackpot%20index
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The Crackpot Index is a number that rates scientific claims or the individuals that make them, in conjunction with a method for computing that number. It was proposed by John C. Baez in 1992, and updated in 1998.
While the index was created for its humorous value, the general concepts can be applied in other fields like risk management.
Baez's crackpot index
The method was initially proposed semi-seriously by mathematical physicist John C. Baez in 1992, and then revised in 1998. The index used responses to a list of 37 questions, each positive response contributing a point value ranging from 1 to 50; the computation is initialized with a value of −5. An earlier version only had 17 questions with point values for each ranging from 1 to 40.
The New Scientist published a claim in 1992 that the creation of the index was "prompted by an especially striking
outburst from a retired mathematician insisting that TIME has INERTIA".
Baez later confirmed in a 1993 letter to New Scientist that he created the index. The index was later published in Skeptic magazine, with an editor's note saying "we know that outsiders to a field can make important contributions and even lead revolutions. But the chances of that happening are rather slim, especially when they meet many of the [Crackpot index] criteria".
Though the index was not proposed as a serious method, it nevertheless has become popular in Internet discussions of whether a claim or an individual is cranky, particularly in physics (e.g., at the Usenet newsgroup sci.physics), or in mathematics.
Chris Caldwell's Prime Pages has a version adapted to prime number research which is a field with many famous unsolved problems that are easy to understand for amateur mathematicians.
Gruenberger's measure for crackpots
An earlier crackpot index is Fred J. Gruenberger's "A Measure for Crackpots" published in December 1962 by the RAND Corporation.
See also
Crank (person)
List of topics characterized as pseudoscience
Pseudophy
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https://en.wikipedia.org/wiki/Low%20Bandwidth%20X
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In computing, LBX, or Low Bandwidth X, is a protocol to use the X Window System over network links with low bandwidth and high latency. It was introduced in X11R6.3 ("Broadway") in 1996, but never achieved wide use. It was disabled by default as of X.Org Server 7.1, and was removed for version 7.2.
X was originally implemented for use with the server and client on the same machine or the same local area network. By 1996, the Internet was becoming popular, and X's performance over narrow, slow links was problematic.
LBX ran as a proxy server (). It cached commonly used information — connection setup, large window properties, font metrics, keymaps and so on — and compressed data transmission over the network link.
LBX was never widely deployed as it did not offer significant speed improvements. The slow links it was introduced to help were typically insecure, and RFB (VNC) over a secure shell connection — which includes compression — proved faster than LBX, and also provided session resumption.
Finally, it was shown that greater speed improvements to X could be obtained for all networked environments with replacement of X's antiquated font system as part of the new composited graphics system, along with care and attention to application and widget toolkit design, particularly care to avoid network round trips and hence latency.
See also
Virtual Network Computing (VNC)
xmove - a tool allows you to move programs between X Window System displays
xpra - a more recent tool which is similar to xmove
NX technology, an X acceleration system
References
lbxproxy(1) (man page)
Design and Implementation of LBX: An Experiment Based Standard (.tar.gz archive file) (Keith Packard, Eighth Annual X Technical Conference, The X Resource no. 9, O'Reilly & Associates, 1994)
Broadway/Xweb FAQ (broadwayinfo.com)
The LBX mini-HOWTO v1.04 (Paul D. Smith, 11 December 1997)
An LBX Postmortem (Keith Packard)
X Window System Network Performance (Keith Packard and Jim Gettys, 2003)
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https://en.wikipedia.org/wiki/Black%20Manta
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Black Manta is a supervillain appearing in American comic books published by DC Comics. Created by Bob Haney and Nick Cardy, the character debuted in Aquaman #35 (September 1967), and has since endured as the archenemy of the superhero Aquaman.
Black Manta has had numerous origin stories throughout his comic book history, having been a young boy kidnapped and enslaved by abusive pirates on their ship; an autistic orphan subjected to unethical experiments in Arkham Asylum; and a high-seas treasure hunter caught in a mutual cycle of vengeance with Aquaman over the deaths of their fathers. Despite these different versions of his past, Black Manta is consistently depicted as a ruthless underwater mercenary who is obsessed with destroying Aquaman's life. A black armored suit and a large metal helmet with red eye lenses serve as Black Manta's visual motif.
The character has been adapted in various media incarnations, having been portrayed in live-action by Yahya Abdul-Mateen II in the 2018 DC Extended Universe film Aquaman and its upcoming 2023 sequel Aquaman and the Lost Kingdom. Kevin Michael Richardson, Khary Payton and others have provided the character's voice in media ranging from animation to video games.
Fictional character biography
Black Manta had no definitive origin story until #6 of the 1993 Aquaman series. In this origin, the African American child who would become Black Manta grew up in Baltimore, Maryland, and loved to play by the Chesapeake Bay. In his youth, he was kidnapped and forced to work on a ship for an unspecified amount of time, where he was physically abused by his captors. At one point, he saw Aquaman with his dolphin friends and tried to signal him for help but was not seen. Finally, he was forced to defend himself, killing one of his tormentors on the ship with a knife. Hating the emotionless sea and Aquaman, whom he saw as its representative, he was determined to become its master.
An alternative version was given in #8 of the 2003 Aqu
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https://en.wikipedia.org/wiki/Captive%20NTFS
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Captive NTFS is a discontinued open-source project in the Linux programming community, started by Jan Kratochvíl. It is a driver wrapper around the original Microsoft Windows NTFS file system driver using parts of ReactOS code. By taking this approach, it aimed to provide safe write support to NTFS partitions.
Until the release of NTFS-3G, it was the only Linux NTFS driver with full write support.
On January 26, 2006 Kratochvíl released version 1.1.7 of the package. It restores compatibility with recent Linux kernels by replacing the obsolete LUFS (Linux Userland File System) module with FUSE (File System in Userspace), which as of Linux 2.6.14 has been part of the official Linux kernel.
Captive NTFS requires NTFS.SYS, which cannot be freely distributed for legal reasons. It can either be obtained from an installed Windows system (which most computers with NTFS partitions are likely to have) or extracted from certain Microsoft service packs.
External links
Jan Kratochvil's Captive NTFS home page
Compatibility layers
Disk file systems
Userspace file systems
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https://en.wikipedia.org/wiki/Magic%20hexagon
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A magic hexagon of order n is an arrangement of numbers in a centered hexagonal pattern with n cells on each edge, in such a way that the numbers in each row, in all three directions, sum to the same magic constant M. A normal magic hexagon contains the consecutive integers from 1 to 3n2 − 3n + 1. It turns out that normal magic hexagons exist only for n = 1 (which is trivial, as it is composed of only 1 cell) and n = 3. Moreover, the solution of order 3 is essentially unique. Meng also gave a less intricate constructive proof.
The order-3 magic hexagon has been published many times as a 'new' discovery. An early reference, and possibly the first discoverer, is Ernst von Haselberg (1887).
Proof of normal magic hexagons
The numbers in the hexagon are consecutive, and run from 1 to . Hence their sum is a triangular number, namely
There are r = 2n − 1 rows running along any given direction (E-W, NE-SW, or NW-SE). Each of these rows sum up to the same number M. Therefore:
This can be rewritten as
Multiplying throughout by 32 gives
which shows that must be an integer, hence 2n − 1 must be a factor of 5, namely 2n − 1 = ±1 or 2n − 1 = ±5. The only that meet this condition are and , proving that there are no normal magic hexagons except those of order 1 and 3.
Abnormal magic hexagons
Although there are no normal magical hexagons with order greater than 3, certain abnormal ones do exist. In this case, abnormal means starting the sequence of numbers other than with 1. Arsen Zahray discovered these order 4 and 5 hexagons:
The order 4 hexagon starts with 3 and ends with 39, its rows summing to 111. The order 5 hexagon starts with 6 and ends with 66 and sums to 244.
An order 5 hexagon starting with 15, ending with 75 and summing to 305 is this:
A higher sum than 305 for order 5 hexagons is not possible.
Order 5 hexagons, where the "X" are placeholders for order 3 hexagons, which complete the number sequence. The left one contains the hexagon with the sum 38 (numbe
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https://en.wikipedia.org/wiki/Iterative%20design
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Iterative design is a design methodology based on a cyclic process of prototyping, testing, analyzing, and refining a product or process. Based on the results of testing the most recent iteration of a design, changes and refinements are made. This process is intended to ultimately improve the quality and functionality of a design. In iterative design, interaction with the designed system is used as a form of research for informing and evolving a project, as successive versions, or iterations of a design are implemented.
History
Iterative design has long been used in engineering fields. One example is the plan–do–check–act cycle implemented in the 1960s. Most New product development or existing product improvement programs have a checking loop which is used for iterative purposes. DMAIC uses the Six Sigma framework and has such a checking function.
Object-Oriented Programming
Iterative design is connected with the practice of object-oriented programming, and the phrase appeared in computer science literature as early as 1990. The idea has its roots in spiral development, conceived of by Barry Boehm.
Iterative design process
The iterative design process may be applied throughout the new product development process. However, changes are easiest and less expensive to implement in the earliest stages of development. The first step in the iterative design process is to develop a prototype. The prototype should be evaluated by a focus group or a group not associated with the product in order to deliver non-biased opinions. Information from the focus group should be synthesized and incorporated into the next iteration of the design. The process should be repeated until user issues have been reduced to an acceptable level.
Application: Human computer interfaces
Iterative design is commonly used in the development of human computer interfaces. This allows designers to identify any usability issues that may arise in the user interface before it is put into wid
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https://en.wikipedia.org/wiki/Pull-up%20resistor
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In electronic logic circuits, a pull-up resistor (PU) or pull-down resistor (PD) is a resistor used to ensure a known state for a signal. It is typically used in combination with components such as switches and transistors, which physically interrupt the connection of subsequent components to ground or to VCC. Closing the switch creates a direct connection to ground or VCC, but when the switch is open, the rest of the circuit would be left floating (i.e., it would have an indeterminate voltage).
For a switch that is used to connect a circuit to VCC (e.g., if the switch or button is used to transmit a "high" signal), a pull-down resistor connected between the circuit and ground ensures a well-defined ground voltage (i.e. logical low) across the remainder of the circuit when the switch is open. For a switch that is used to connect a circuit to ground, a pull-up resistor (connected between the circuit and VCC) ensures a well-defined voltage (i.e. VCC, or logical high) when the switch is open.
An open switch is not equivalent to a component with infinite impedance, since in the former case, the stationary voltage in any loop in which it is involved can no longer be determined by Kirchhoff's laws. Consequently, the voltages across those critical components (such as the logic gate in the example on the right), which are only in loops involving the open switch, are undefined, too.
A pull-up resistor effectively establishes an additional loop over the critical components, ensuring that the voltage is well-defined even when the switch is open.
For a pull-up resistor to serve only this one purpose and not interfere with the circuit otherwise, a resistor with an appropriate amount of resistance must be used. For this, it is assumed that the critical components have infinite or sufficiently high impedance, which is guaranteed for example for logic gates made from FETs. In this case, when the switch is open, the voltage across a pull-up resistor (with sufficiently low impe
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https://en.wikipedia.org/wiki/Carry%20%28arithmetic%29
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In elementary arithmetic, a carry is a digit that is transferred from one column of digits to another column of more significant digits. It is part of the standard algorithm to add numbers together by starting with the rightmost digits and working to the left. For example, when 6 and 7 are added to make 13, the "3" is written to the same column and the "1" is carried to the left. When used in subtraction the operation is called a borrow.
Carrying is emphasized in traditional mathematics, while curricula based on reform mathematics do not emphasize any specific method to find a correct answer.
Carrying makes a few appearances in higher mathematics as well. In computing, carrying is an important function of adder circuits.
Manual arithmetic
A typical example of carry is in the following pencil-and-paper addition:
1
27
+ 59
----
86
7 + 9 = 16, and the digit 1 is the carry.
The opposite is a borrow, as in
−1
47
− 19
----
28
Here, , so try , and the 10 is got by taking ("borrowing") 1 from the next digit to the left. There are two ways in which this is commonly taught:
The ten is moved from the next digit left, leaving in this example in the tens column. According to this method, the term "borrow" is a misnomer, since the ten is never paid back.
The ten is copied from the next digit left, and then 'paid back' by adding it to the subtrahend in the column from which it was 'borrowed', giving in this example in the tens column.
Mathematics education
Traditionally, carry is taught in the addition of multi-digit numbers in the 2nd or late first year of elementary school. However, since the late 20th century, many widely adopted curricula developed in the United States such as TERC omitted instruction of the traditional carry method in favor of invented arithmetic methods, and methods using coloring, manipulatives, and charts. Such omissions were criticized by such groups as Mathematically Correct, and some states and districts have since ab
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https://en.wikipedia.org/wiki/Medical%20Waste%20Tracking%20Act
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The Medical Waste Tracking Act of 1988 was a United States federal law concerning the illegal dumping of body tissues, blood wastes and other contaminated biological materials. It established heavy penalties for knowingly endangering life through noncompliance. The law expired in 1991.
Authority
The law created a two-year program that went into effect in New York, New Jersey, Connecticut, Rhode Island and Puerto Rico on June 24, 1989, and expired on June 21, 1991.
The H.R. 3515 legislation was passed by the 100th Congressional session and signed into law by the 40th President of the United States Ronald Reagan on November 2, 1988.
History
Beginning on August 13, 1987, a "30-mile garbage slick" composed primarily of medical and household wastes prompted extensive closures of numerous New Jersey and New York beaches. Investigations ongoing throughout the year indicated that the waste likely originated from "New York City's marine transfer stations … and the Southwest Brooklyn Incinerator and Transfer Station in particular…" The then-assistant commissioner of the New Jersey Department of Environmental Protection stated his belief that the cause of pollution was intentional rather than accidental; "sealed plastic garbage bags, he said, were cut at the top, so their contents could disperse through the ocean." Such a deliberate action may have arisen given the high cost (~$1500/ton) associated with the legal disposal of the waste, thus incentivizing private waste contractors to dump illegally to avoid high fees.
Ultimately the Medical Waste Tracking Act of 1988 (MWTA) arose from the aftermath of this situation. It was designed primarily to monitor the treatment of medical wastes through their creation, transportation and destruction, i.e. from "cradle-to-grave." Congress approved the bill "to amend the Solid Waste Disposal Act to require the Administrator of the Environmental Protection Agency (EPA) to promulgate regulations on the management of infections waste." In
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https://en.wikipedia.org/wiki/Prime%20power
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In mathematics, a prime power is a positive integer which is a positive integer power of a single prime number.
For example: , and are prime powers, while
, and are not.
The sequence of prime powers begins:
2, 3, 4, 5, 7, 8, 9, 11, 13, 16, 17, 19, 23, 25, 27, 29, 31, 32, 37, 41, 43, 47, 49, 53, 59, 61, 64, 67, 71, 73, 79, 81, 83, 89, 97, 101, 103, 107, 109, 113, 121, 125, 127, 128, 131, 137, 139, 149, 151, 157, 163, 167, 169, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 243, 251, … .
The prime powers are those positive integers that are divisible by exactly one prime number; in particular, the number 1 is not a prime power. Prime powers are also called primary numbers, as in the primary decomposition.
Properties
Algebraic properties
Prime powers are powers of prime numbers. Every prime power (except powers of 2) has a primitive root; thus the multiplicative group of integers modulo pn (that is, the group of units of the ring Z/pnZ) is cyclic.
The number of elements of a finite field is always a prime power and conversely, every prime power occurs as the number of elements in some finite field (which is unique up to isomorphism).
Combinatorial properties
A property of prime powers used frequently in analytic number theory is that the set of prime powers which are not prime is a small set in the sense that the infinite sum of their reciprocals converges, although the primes are a large set.
Divisibility properties
The totient function (φ) and sigma functions (σ0) and (σ1) of a prime power are calculated by the formulas
All prime powers are deficient numbers. A prime power pn is an n-almost prime. It is not known whether a prime power pn can be a member of an amicable pair. If there is such a number, then pn must be greater than 101500 and n must be greater than 1400.
See also
Almost prime
Fermi–Dirac prime
Perfect power
Semiprime
References
Further reading
Elementary Number Theory. Jones, Gareth A. and Jones, J. Mary. Springer-V
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https://en.wikipedia.org/wiki/Ruin%20value
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Ruin value () is the concept that a building be designed in such a way that if it eventually collapsed, it would leave behind aesthetically pleasing ruins that would last far longer without any maintenance at all. The idea was pioneered by German architect Albert Speer while planning for the 1936 Summer Olympics and published as "The Theory of Ruin Value" (Die Ruinenwerttheorie), although he was not its original inventor. The intention did not stretch only to the eventual collapse of the buildings, but rather assumed such buildings were inherently better designed and more imposing during their period of use.
The idea was supported by Adolf Hitler, who planned for such ruins to be a symbol of the greatness of the Third Reich, just as Ancient Greek and Roman ruins were symbolic of those civilisations.
Albert Speer
In his memoirs, Albert Speer claimed to have invented the idea, which he referred to as the theory of Ruin Value (Gr. Ruinenwerttheorie). It was supposedly an extension of Gottfried Semper's views about using "natural" materials and the avoidance of iron girders. In reality it was a much older concept, even becoming a Europe-wide Romantic fascination at one point. Predecessors include a "new ruined castle" built by the Landgraf of Hesse-Kassel in the 18th century, and the designs for the Bank of England built in the 19th century produced by Sir John Soane. When he presented the bank's governors with three oil sketches of the planned building one of them depicted it when it would be new, another when it would be weathered, and a third what its ruins would look like a thousand years onward.
Speer's memoirs reveal Hitler's thoughts about Nazi state architecture in relation to Roman imperial architecture:
Hitler accordingly approved Speer's recommendation that, in order to provide a "bridge to tradition" to future generations, modern "anonymous" materials such as steel girders and ferroconcrete should be avoided in the construction of monumental party build
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https://en.wikipedia.org/wiki/Pollard%27s%20rho%20algorithm%20for%20logarithms
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Pollard's rho algorithm for logarithms is an algorithm introduced by John Pollard in 1978 to solve the discrete logarithm problem, analogous to Pollard's rho algorithm to solve the integer factorization problem.
The goal is to compute such that , where belongs to a cyclic group generated by . The algorithm computes integers , , , and such that . If the underlying group is cyclic of order , by substituting as and noting that two powers are equal if and only if the exponents are equivalent modulo the order of the base, in this case modulo , we get that is one of the solutions of the equation . Solutions to this equation are easily obtained using the extended Euclidean algorithm.
To find the needed , , , and the algorithm uses Floyd's cycle-finding algorithm to find a cycle in the sequence , where the function is assumed to be random-looking and thus is likely to enter into a loop of approximate length after steps. One way to define such a function is to use the following rules: Divide into three disjoint subsets of approximately equal size: , , and . If is in then double both and ; if then increment , if then increment .
Algorithm
Let be a cyclic group of order , and given , and a partition , let be the map
and define maps and by
input: a: a generator of G
b: an element of G
output: An integer x such that ax = b, or failure
Initialise a0 ← 0, b0 ← 0, x0 ← 1 ∈ G
i ← 1
loop
xi ← f(xi-1),
ai ← g(xi-1, ai-1),
bi ← h(xi-1, bi-1)
x2i ← f(f(x2i-2)),
a2i ← g(f(x2i-2), g(x2i-2, a2i-2)),
b2i ← h(f(x2i-2), h(x2i-2, b2i-2))
if xi = x2i then
r ← bi - b2i
if r = 0 return failure
x ← r−1(a2i - ai) mod n
return x
else // xi ≠ x2i
i ← i + 1
end if
end loop
Example
Consider, for example, the group generated by 2 modulo (the order of the group is , 2 generates the group of units modulo 1019). The algorithm is implemented by the following C++
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https://en.wikipedia.org/wiki/Risk-adjusted%20return%20on%20capital
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Risk-adjusted return on capital (RAROC) is a risk-based profitability measurement framework for analysing risk-adjusted financial performance and providing a consistent view of profitability across businesses. The concept was developed by Bankers Trust and principal designer Dan Borge in the late 1970s. Note, however, that increasingly return on risk-adjusted capital (RORAC) is used as a measure, whereby the risk adjustment of Capital is based on the capital adequacy guidelines as outlined by the Basel Committee.
Basic formulae
The formula is given by
Broadly speaking, in business enterprises, risk is traded off against benefit. RAROC is defined as the ratio of risk adjusted return to economic capital. The economic capital is the amount of money which is needed to secure the survival in a worst-case scenario, it is a buffer against unexpected shocks in market values. Economic capital is a function of market risk, credit risk, and operational risk, and is often calculated by VaR. This use of capital based on risk improves the capital allocation across different functional areas of banks, insurance companies, or any business in which capital is placed at risk for an expected return above the risk-free rate.
RAROC system allocates capital for two basic reasons:
Risk management
Performance evaluation
For risk management purposes, the main goal of allocating capital to individual business units is to determine the bank's optimal capital structure—that is economic capital allocation is closely correlated with individual business risk. As a performance evaluation tool, it allows banks to assign capital to business units based on the economic value added of each unit.
Decision measures based on regulatory and economic capital
With the financial crisis of 2007, and the introduction of Dodd–Frank Act, and Basel III, the minimum required regulatory capital requirements have become onerous. An implication of stringent regulatory capital requirements spurred debates on
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https://en.wikipedia.org/wiki/List%20of%20mathematical%20identities
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This article lists mathematical identities, that is, identically true relations holding in mathematics.
Bézout's identity (despite its usual name, it is not, properly speaking, an identity)
Binomial inverse theorem
Binomial identity
Brahmagupta–Fibonacci two-square identity
Candido's identity
Cassini and Catalan identities
Degen's eight-square identity
Difference of two squares
Euler's four-square identity
Euler's identity
Fibonacci's identity see Brahmagupta–Fibonacci identity or Cassini and Catalan identities
Heine's identity
Hermite's identity
Lagrange's identity
Lagrange's trigonometric identities
MacWilliams identity
Matrix determinant lemma
Newton's identity
Parseval's identity
Pfister's sixteen-square identity
Sherman–Morrison formula
Sophie Germain identity
Sun's curious identity
Sylvester's determinant identity
Vandermonde's identity
Woodbury matrix identity
Identities for classes of functions
Exterior calculus identities
Fibonacci identities: Combinatorial Fibonacci identities and Other Fibonacci identities
Hypergeometric function identities
List of integrals of logarithmic functions
List of topics related to
List of trigonometric identities
Inverse trigonometric functions
Logarithmic identities
Summation identities
Vector calculus identities
See also
External links
A Collection of Algebraic Identities
Matrix Identities
Identities
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https://en.wikipedia.org/wiki/Ian%20Wilmut
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Sir Ian Wilmut (7 July 1944 – 10 September 2023) was a British embryologist and the chair of the Scottish Centre for Regenerative Medicine at the University of Edinburgh. He is best known as the leader of the research group that in 1996 first cloned a mammal from an adult somatic cell, a Finnish Dorset lamb named Dolly.
Wilmut was appointed OBE in 1999 for services to embryo development and knighted in the 2008 New Year Honours. He, Keith Campbell and Shinya Yamanaka jointly received the 2008 Shaw Prize for Medicine and Life Sciences for their work on cell differentiation in mammals.
Early life and education
Wilmut was born in Hampton Lucy, Warwickshire, England, on 7 July 1944. Wilmut's father, Leonard Wilmut, was a mathematics teacher who suffered from diabetes for fifty years, which eventually caused him to become blind. The younger Wilmut attended the Boys' High School in Scarborough, where his father taught. His early desire was to embark on a naval career, but he was unable to do so due to his colour blindness. As a schoolboy, Wilmut worked as a farm hand on weekends, which inspired him to study Agriculture at the University of Nottingham.
In 1966, Wilmut spent eight weeks working in the laboratory of Christopher Polge, who is credited with developing the technique of cryopreservation in 1949. The following year Wilmut joined Polge's laboratory to undertake a Doctor of Philosophy degree at the University of Cambridge, from where he graduated in 1971 with a thesis on semen cryopreservation. During this time he was a postgraduate student at Darwin College.
Career and research
After completing his PhD, he was involved in research focusing on gametes and embryogenesis, including working at the Roslin Institute.
Wilmut was the leader of the research group that in 1996 first cloned a mammal, a lamb named Dolly. She died of a respiratory disease in 2003. In 2008 Wilmut announced that he would abandon the technique of somatic cell nuclear transfer by which Dolly
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https://en.wikipedia.org/wiki/Equivalent%20weight
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In chemistry, equivalent weight (also known as gram equivalent or equivalent mass) is the mass of one equivalent, that is the mass of a given substance which will combine with or displace a fixed quantity of another substance. The equivalent weight of an element is the mass which combines with or displaces 1.008 gram of hydrogen or 8.0 grams of oxygen or 35.5 grams of chlorine. These values correspond to the atomic weight divided by the usual valence; for oxygen as example that is 16.0 g / 2 = 8.0 g.
For acid–base reactions, the equivalent weight of an acid or base is the mass which supplies or reacts with one mole of hydrogen cations (). For redox reactions, the equivalent weight of each reactant supplies or reacts with one mole of electrons (e−) in a redox reaction.
Equivalent weight has the units of mass, unlike atomic weight, which is now used as a synonym for relative atomic mass and is dimensionless. Equivalent weights were originally determined by experiment, but (insofar as they are still used) are now derived from molar masses. The equivalent weight of a compound can also be calculated by dividing the molecular mass by the number of positive or negative electrical charges that result from the dissolution of the compound.
In history
The first equivalent weights were published for acids and bases by Carl Friedrich Wenzel in 1777. A larger set of tables was prepared, possibly independently, by Jeremias Benjamin Richter, starting in 1792. However, neither Wenzel nor Richter had a single reference point for their tables, and so had to publish separate tables for each pair of acid and base.
John Dalton's first table of atomic weights (1808) suggested a reference point, at least for the elements: taking the equivalent weight of hydrogen to be one unit of mass. However, Dalton's atomic theory was far from universally accepted in the early 19th century. One of the greatest problems was the reaction of hydrogen with oxygen to produce water. One gram of hydroge
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https://en.wikipedia.org/wiki/List%20of%20BBS%20software
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This is a list of notable bulletin board system (BBS) software packages.
Multi-platform
Citadel – originally written for the CP/M operating system, had many forks for different systems under different names.
CONFER – CONFER II on the MTS, CONFER U on Unix and CONFER V on VAX/VMS, written by Robert Parnes starting in 1975.
Mystic BBS – written by James Coyle with versions for Windows/Linux/ARM Linux/OSX. Past versions: MS-DOS and OS/2.
Synchronet – Windows/Linux/BSD, past versions: MS-DOS and OS/2.
WWIV – WWIV v5.x is supported on both Windows 7+ 32bit as well as Linux 32bit and 64bit. Written by Wayne Bell, included WWIVNet. Past versions: MS-DOS and OS/2.
Altos 68000
PicoSpan
Amiga based
Ami-Express – aka "/X", very popular in the crackers/warez software scene.
C-Net – aka "Cnet"
Apple II series
Diversi-Dial (DDial) – Chat-room atmosphere supporting up to 7 incoming lines allowing links to other DDial boards.
GBBS – Applesoft and assembler-based BBS program by Greg Schaeffer.
GBBS Pro – based on the ACOS or MACOS (modified ACOS) language.
Net-Works II – by Nick Naimo.
SBBS – Sonic BBS by Patrick Sonnek.
Apple Macintosh
Citadel – including Macadel, MacCitadel.
FirstClass (SoftArc)
Hermes
Second Sight
TeleFinder
Atari 8-bit computer
Atari Message Information System – and derivatives
Commodore computers
Blue Board – by Martin Sikes.
Superboard – by Greg Francis and Randy Schnedler.
C*Base – by Gunther Birznieks, Jerome P. Yoner, and David Weinehall.
C-Net DS2 – by Jim Selleck.
Color64 – by Greg Pfountz.
McBBS – by Derek E. McDonald.
CP/M
CBBS – The first ever BBS software, written by Ward Christensen.
Citadel
RBBS
TBBS
Microsoft Windows
Excalibur BBS
Maximus
Mystic BBS
MS-DOS and compatible
Celerity BBS
Citadel – including DragCit, Cit86, TurboCit, Citadel+
Ezycom – written by Peter Davies.
FBB (F6FBB) – packet radio BBS system, still in use.
GBBS (Graphics BBS) – used in the Melbourne area.
GT-Power
L.S.D.
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https://en.wikipedia.org/wiki/WSES
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WSES (channel 33) is a television station licensed to Tuscaloosa, Alabama, United States, serving the western portion of the Birmingham market as an affiliate of the digital multicast network Heroes & Icons. The station is owned by Howard Stirk Holdings, a partner company of the Sinclair Broadcast Group. WSES' advertising sales office is located on Golden Crest Drive in Birmingham, and its transmitter is located near County Road 38/Blue Creek Road, east of State Route 69 near Windham Springs.
WGWW (channel 40) in Anniston operates as a full-time satellite of WSES.
History
As an independent station
The station first signed on the air on October 27, 1965, as WCFT-TV. Originally operating as an independent station, it was the first television station to sign on in western Alabama. It was originally owned by Chapman Family Television, a consortium of eight Tuscaloosa businessmen who saw the benefits of operating a television station to serve west-central Alabama, in terms of both business and community service purposes.
However, the station did not return a profit suitable enough for its owners throughout its first two years of operation, an issue that led Chapman Family Television to sell the station to South Mississippi Broadcasting, Inc. (later Service Broadcasters) in 1967, becoming the company's second television station, after flagship WDAM-TV in the company's home market of Hattiesburg, Mississippi. The new owners rejuvenated WCFT by heavily investing in the station, purchasing new broadcasting and transmission equipment, and improving the station's image. In addition to carrying syndicated programming, WCFT-TV also aired network programs from CBS and NBC that were not cleared for broadcast in the Birmingham market by WAPI-TV (channel 13, now WVTM-TV), which WBMG (channel 42, now WIAT) did during that same timeframe.
As an exclusive CBS affiliate
On May 31, 1970, when WAPI-TV formally removed CBS programming and became the exclusive NBC affiliate for the Bir
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https://en.wikipedia.org/wiki/Essbase
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Essbase is a multidimensional database management system (MDBMS) that provides a platform upon which to build analytic applications. Essbase began as a product from Arbor Software, which merged with Hyperion Software in 1998. Oracle Corporation acquired Hyperion Solutions Corporation in 2007. Until late 2005 IBM also marketed an OEM version of Essbase as DB2 OLAP Server.
The database researcher E. F. Codd coined the term "on-line analytical processing" (OLAP) in a whitepaper
that set out twelve rules for analytic systems (an allusion to his earlier famous set of twelve rules defining the relational model). This whitepaper, published by Computerworld, was somewhat explicit in its reference to Essbase features, and when it was later discovered that Codd had been sponsored by Arbor Software, Computerworld withdrew the paper.
In contrast to "on-line transaction processing" (OLTP), OLAP defines a database technology optimized for processing human queries rather than transactions. The results of this orientation were that multidimensional databases oriented their performance requirements around a different set of benchmarks (Analytic Performance Benchmark, APB-1) than that of RDBMS (Transaction Processing Performance Council [TPC]).
Hyperion renamed many of its products in 2005, giving Essbase an official name of Hyperion System 9 BI+ Analytic Services, but the new name was largely ignored by practitioners. The Essbase brand was later returned to the official product name for marketing purposes, but the server software still carried the "Analytic Services" title until it was incorporated into Oracle's Business Intelligence Foundation Suite (BIFS) product.
In August 2005, Information Age magazine named Essbase as one of the 10 most influential technology innovations of the previous 10 years, along with Netscape, the BlackBerry, Google, virtualization, Voice Over IP (VOIP), Linux, XML, the Pentium processor, and ADSL. Editor Kenny MacIver said: "Hyperion Essbase was
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https://en.wikipedia.org/wiki/GEOS%20%288-bit%20operating%20system%29
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GEOS (Graphic Environment Operating System) is a discontinued operating system from Berkeley Softworks (later GeoWorks). Originally designed for the Commodore 64 with its version being released in 1986, enhanced versions of GEOS later became available in 1987 for the Commodore 128 and in 1988 for the Apple II series of computers. A lesser-known version was also released for the Commodore Plus/4.
GEOS closely resembles early versions of the classic Mac OS and includes a graphical word processor (geoWrite) and paint program (geoPaint).
A December 1987 survey by the Commodore-dedicated magazine Compute!'s Gazette found that nearly half of respondents used GEOS. For many years, Commodore bundled GEOS with its redesigned and cost-reduced C64, the C64C. At its peak, GEOS was the third-most-popular microcomputer operating system in the world in terms of units shipped, trailing only MS-DOS and Mac OS (besides the original Commodore 64's KERNAL).
Other GEOS-compatible software packages were available from Berkeley Softworks or from third parties, including a reasonably sophisticated desktop publishing application called geoPublish and a spreadsheet called geoCalc. While geoPublish is not as sophisticated as Aldus Pagemaker and geoCalc not as sophisticated as Microsoft Excel, the packages provide reasonable functionality, and Berkeley Softworks founder Brian Dougherty claimed the company ran its business using its own software on Commodore 8-bit computers for several years.
Development
Written by a group of programmers at Berkeley Softworks, the GEOS Design Team: Jim DeFrisco, Dave Durran, Michael Farr, Doug Fults, Chris Hawley, Clayton Jung, and Tony Requist, led by Dougherty, who cut their teeth on limited-resource video game machines such as the Atari 2600, GEOS was revered for what it could accomplish on machines with 64–128 kB of RAM memory and 1–2 MHz of 8-bit processing power.
Unlike many pieces of proprietary software for the C64 and C128, GEOS takes full advant
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https://en.wikipedia.org/wiki/Nuclear%20transfer
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Nuclear transfer is a form of cloning. The step involves removing the DNA from an oocyte (unfertilised egg), and injecting the nucleus which contains the DNA to be cloned. In rare instances, the newly constructed cell will divide normally, replicating the new DNA while remaining in a pluripotent state. If the cloned cells are placed in the uterus of a female mammal, a cloned organism develops to term in rare instances. This is how Dolly the Sheep and many other species were cloned. Cows are commonly cloned to select those that have the best milk production. On 24 January 2018, two monkey clones were reported to have been created with the technique for the first time.
Despite this, the low efficiency of the technique has prompted some researchers, notably Ian Wilmut, creator of Dolly the cloned sheep, to abandon it.
Tools and reagents
Nuclear transfer is a delicate process that is a major hurdle in the development of cloning technology. Materials used in this procedure are a microscope, a holding pipette (small vacuum) to keep the oocyte in place, and a micropipette (hair-thin needle) capable of extracting the nucleus of a cell using a vacuum. For some species, such as mouse, a drill is used to pierce the outer layers of the oocyte.
Various chemical reagents are used to increase cloning efficiency. Microtubule inhibitors, such as nocodazole, are used to arrest the oocyte in M phase, during which its nuclear membrane is dissolved. Chemicals are also used to stimulate oocyte activation. When applied the membrane is completely dissolved.
Somatic cell nuclear transfer
Somatic Cell Nuclear Transfer (SCNT) is the process by which the nucleus of an oocyte (egg cell) is removed and is replaced with the nucleus of a somatic (body) cell (examples include skin, heart, or nerve cell). The two entities fuse to become one and factors in the oocyte cause the somatic nucleus to reprogram to a pluripotent state. The cell contains genetic information identical to the donated s
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https://en.wikipedia.org/wiki/Ecological%20engineering
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Ecological engineering uses ecology and engineering to predict, design, construct or restore, and manage ecosystems that integrate "human society with its natural environment for the benefit of both".
Origins, key concepts, definitions, and applications
Ecological engineering emerged as a new idea in the early 1960s, but its definition has taken several decades to refine. Its implementation is still undergoing adjustment, and its broader recognition as a new paradigm is relatively recent. Ecological engineering was introduced by Howard Odum and others as utilizing natural energy sources as the predominant input to manipulate and control environmental systems. The origins of ecological engineering are in Odum's work with ecological modeling and ecosystem simulation to capture holistic macro-patterns of energy and material flows affecting the efficient use of resources.
Mitsch and Jorgensen summarized five basic concepts that differentiate ecological engineering from other approaches to addressing problems to benefit society and nature: 1) it is based on the self-designing capacity of ecosystems; 2) it can be the field (or acid) test of ecological theories; 3) it relies on system approaches; 4) it conserves non-renewable energy sources; and 5) it supports ecosystem and biological conservation.
Mitsch and Jorgensen were the first to define ecological engineering as designing societal services such that they benefit society and nature, and later noted the design should be systems based, sustainable, and integrate society with its natural environment.
Bergen et al. defined ecological engineering as: 1) utilizing ecological science and theory; 2) applying to all types of ecosystems; 3) adapting engineering design methods; and 4) acknowledging a guiding value system.
Barrett (1999) offers a more literal definition of the term: "the design, construction, operation and management (that is, engineering) of landscape/aquatic structures and associated plant and animal com
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https://en.wikipedia.org/wiki/Cofinal%20%28mathematics%29
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In mathematics, a subset of a preordered set is said to be cofinal or frequent in if for every it is possible to find an element in that is "larger than " (explicitly, "larger than " means ).
Cofinal subsets are very important in the theory of directed sets and nets, where “cofinal subnet” is the appropriate generalization of "subsequence". They are also important in order theory, including the theory of cardinal numbers, where the minimum possible cardinality of a cofinal subset of is referred to as the cofinality of
Definitions
Let be a homogeneous binary relation on a set
A subset is said to be or with respect to if it satisfies the following condition:
For every there exists some that
A subset that is not frequent is called .
This definition is most commonly applied when is a directed set, which is a preordered set with additional properties.
Final functions
A map between two directed sets is said to be if the image of is a cofinal subset of
Coinitial subsets
A subset is said to be (or in the sense of forcing) if it satisfies the following condition:
For every there exists some such that
This is the order-theoretic dual to the notion of cofinal subset.
Cofinal (respectively coinitial) subsets are precisely the dense sets with respect to the right (respectively left) order topology.
Properties
The cofinal relation over partially ordered sets ("posets") is reflexive: every poset is cofinal in itself. It is also transitive: if is a cofinal subset of a poset and is a cofinal subset of (with the partial ordering of applied to ), then is also a cofinal subset of
For a partially ordered set with maximal elements, every cofinal subset must contain all maximal elements, otherwise a maximal element that is not in the subset would fail to be any element of the subset, violating the definition of cofinal. For a partially ordered set with a greatest element, a subset is cofinal if and only if it contains that grea
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https://en.wikipedia.org/wiki/Hensel%27s%20lemma
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In mathematics, Hensel's lemma, also known as Hensel's lifting lemma, named after Kurt Hensel, is a result in modular arithmetic, stating that if a univariate polynomial has a simple root modulo a prime number , then this root can be lifted to a unique root modulo any higher power of . More generally, if a polynomial factors modulo into two coprime polynomials, this factorization can be lifted to a factorization modulo any higher power of (the case of roots corresponds to the case of degree for one of the factors).
By passing to the "limit" (in fact this is an inverse limit) when the power of tends to infinity, it follows that a root or a factorization modulo can be lifted to a root or a factorization over the -adic integers.
These results have been widely generalized, under the same name, to the case of polynomials over an arbitrary commutative ring, where is replaced by an ideal, and "coprime polynomials" means "polynomials that generate an ideal containing ".
Hensel's lemma is fundamental in -adic analysis, a branch of analytic number theory.
The proof of Hensel's lemma is constructive, and leads to an efficient algorithm for Hensel lifting, which is fundamental for factoring polynomials, and gives the most efficient known algorithm for exact linear algebra over the rational numbers.
Modular reduction and lifting
Hensel's original lemma concerns the relation between polynomial factorization over the integers and over the integers modulo a prime number and its powers. It can be straightforwardly extended to the case where the integers are replaced by any commutative ring, and is replaced by any maximal ideal (indeed, the maximal ideals of have the form where is a prime number).
Making this precise requires a generalization of the usual modular arithmetic, and so it is useful to define accurately the terminology that is commonly used in this context.
Let be a commutative ring, and an ideal of . Reduction modulo refers to the replacement of eve
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https://en.wikipedia.org/wiki/Richard%20P.%20Stanley
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Richard Peter Stanley (born June 23, 1944) is an Emeritus Professor of Mathematics at the Massachusetts Institute of Technology, in Cambridge, Massachusetts. From 2000 to 2010, he was the Norman Levinson Professor of Applied Mathematics. He received his Ph.D. at Harvard University in 1971 under the supervision of Gian-Carlo Rota. He is an expert in the field of combinatorics and its applications to other mathematical disciplines.
Contributions
Stanley is known for his two-volume book Enumerative Combinatorics (1986–1999). He is also the author of Combinatorics and Commutative Algebra (1983) and well over 200 research articles in mathematics. He has served as thesis advisor to 60 doctoral students, many of whom have had distinguished careers in combinatorial research. Donald Knuth named Stanley as one of his combinatorial heroes in a 2023 interview.
Awards and honors
Stanley's distinctions include membership in the National Academy of Sciences (elected in 1995), the 2001 Leroy P. Steele Prize for Mathematical Exposition, the 2003 Schock Prize, a plenary lecture at the International Congress of Mathematicians (in Madrid, Spain), and election in 2012 as a fellow of the American Mathematical Society. In 2022 he was awarded the Leroy P. Steele Prize for Lifetime Achievement.
Selected publications
Stanley, Richard P. (1996). Combinatorics and Commutative Algebra, 2nd ed. .
Stanley, Richard P. (1997, 1999). Enumerative Combinatorics, Volumes 1 and 2. Cambridge University Press. , 0-521-56069-1.
See also
Exponential formula
Order polynomial
Stanley decomposition
Stanley's reciprocity theorem
References
External links
Richard Stanley's Homepage
1944 births
Living people
Members of the United States National Academy of Sciences
Fellows of the American Mathematical Society
20th-century American mathematicians
21st-century American mathematicians
Combinatorialists
Harvard University alumni
Massachusetts Institute of Technology School of Science facult
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https://en.wikipedia.org/wiki/George%20Devol
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George Charles Devol Jr. (February 20, 1912 – August 11, 2011) was an American inventor, best known for creating Unimate, the first industrial robot. Devol's invention earned him the title "Grandfather of Robotics". The National Inventors Hall of Fame says, "Devol's patent for the first digitally operated programmable robotic arm represents the foundation of the modern robotics industry."
The concept of the robot arm has evolved over time with contributions from various individuals and researchers. However, the first patent for an industrial robot was filed in 1954 by George Devol, an American inventor and entrepreneur, who is often credited as the "father of the robot arm."
Early life
George Devol was born in an upper-middle-class family in Louisville, Kentucky. He attended Riordan Prep school.
United Cinephone
Foregoing higher education, Devol went into business in 1932, forming United Cinephone to produce variable area recording directly onto film for the new sound motion pictures ("talkies"). However, he later learned that companies like RCA and Western Electric were working in the same area, and discontinued the product.
During that time, Devol developed and patented industrial lighting and invented the automatic opening door.
World War II
In 1939, Devol applied for a patent for proximity controls for use in laundry press machines, based on a radio frequency field. This control would automatically open and close laundry presses when workers approached the machines. After World War II began, the patent office told Devol that his patent application would be placed on hold for the duration of the conflict.
Around that time, Devol sold his interest in United Cinephone and approached Sperry Gyroscope to pitch his ideas on radar technology. He was retained by Sperry as manager of the Special Projects Department, which developed radar devices and microwave test equipment.
Later in the war, he approached Auto-Ordnance Company regarding products that company
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https://en.wikipedia.org/wiki/Near-term%20digital%20radio
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The Near-term digital radio (NTDR) program provided a prototype mobile ad hoc network (MANET) radio system to the United States Army, starting in the 1990s. The MANET protocols were provided by Bolt, Beranek and Newman; the radio hardware was supplied by ITT. These systems have been fielded by the United Kingdom as the High-capacity data radio (HCDR) and by the Israelis as the Israeli data radio. They have also been purchased by a number of other countries for experimentation.
The NTDR protocols consist of two components: clustering and routing. The clustering algorithms dynamically organize a given network into cluster heads and cluster members. The cluster heads create a backbone; the cluster members use the services of this backbone to send and receive packets. The cluster heads use a link-state routing algorithm to maintain the integrity of their backbone and to track the locations of cluster members.
The NTDR routers also use a variant of Open Shortest Path First (OSPF) that is called Radio-OSPF (ROSPF). ROSPF does not use the OSPF hello protocol for link discovery, etc. Instead, OSPF adjacencies are created and destroyed as a function of MANET information that is distributed by the NTDR routers, both cluster heads and cluster members. It also supported multicasting.
References
Wireless networking
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https://en.wikipedia.org/wiki/Feedwater%20heater
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A feedwater heater is a power plant component used to pre-heat water delivered to a steam generating boiler. Preheating the feedwater reduces the irreversibilities involved in steam generation and therefore improves the thermodynamic efficiency of the system. This reduces plant operating costs and also helps to avoid thermal shock to the boiler metal when the feedwater is introduced back into the steam cycle.
In a steam power plant (usually modeled as a modified Rankine cycle), feedwater heaters allow the feedwater to be brought up to the saturation temperature very gradually. This minimizes the inevitable irreversibilities associated with heat transfer to the working fluid (water). See the article on the second law of thermodynamics for a further discussion of such irreversibilities.
Cycle discussion and explanation
The energy used to heat the feedwater is usually derived from steam extracted between the stages of the steam turbine. Therefore, the steam that would be used to perform expansion work in the turbine (and therefore generate power) is not utilized for that purpose. The percentage of the total cycle steam mass flow used for the feedwater heater is termed the extraction fraction and must be carefully optimized for maximum power plant thermal efficiency since increasing this fraction causes a decrease in turbine power output.
Feedwater heaters can also be "open" or "closed" heat exchangers. An open heat exchanger is one in which extracted steam is allowed to mix with the feedwater. This kind of heater will normally require a feed pump at both the feed inlet and outlet since the pressure in the heater is between the boiler pressure and the condenser pressure. A deaerator is a special case of the open feedwater heater which is specifically designed to remove non-condensable gases from the feedwater.
Closed feedwater heaters are typically shell and tube heat exchangers where the feedwater passes throughout the tubes and is heated by turbine extract
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https://en.wikipedia.org/wiki/Atomic%20battery
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An atomic battery, nuclear battery, radioisotope battery or radioisotope generator is a device which uses energy from the decay of a radioactive isotope to generate electricity. Like nuclear reactors, they generate electricity from nuclear energy, but differ in that they do not use a chain reaction. Although commonly called batteries, they are technically not electrochemical and cannot be charged or recharged. They are very costly, but have an extremely long life and high energy density, and so they are typically used as power sources for equipment that must operate unattended for long periods of time, such as spacecraft, pacemakers, underwater systems and automated scientific stations in remote parts of the world.
Nuclear battery technology began in 1913, when Henry Moseley first demonstrated a current generated by charged particle radiation. The field received considerable in-depth research attention for applications requiring long-life power sources for space needs during the 1950s and 1960s. In 1954 RCA researched a small atomic battery for small radio receivers and hearing aids. Since RCA's initial research and development in the early 1950s, many types and methods have been designed to extract electrical energy from nuclear sources. The scientific principles are well known, but modern nano-scale technology and new wide-bandgap semiconductors have created new devices and interesting material properties not previously available.
Nuclear batteries can be classified by energy conversion technology into two main groups: thermal converters and non-thermal converters. The thermal types convert some of the heat generated by the nuclear decay into electricity. The most notable example is the radioisotope thermoelectric generator (RTG), often used in spacecraft. The non-thermal converters extract energy directly from the emitted radiation, before it is degraded into heat. They are easier to miniaturize and do not require a thermal gradient to operate, so they are sui
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https://en.wikipedia.org/wiki/Lua
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Lua or LUA may refer to:
Science and technology
Lua (programming language)
Latvia University of Agriculture
Last universal ancestor, in evolution
Ethnicity and language
Lua people, of Laos
Lawa people, of Thailand sometimes referred to as Lua
Lua language (disambiguation), several languages (including Lua’)
Luba-Kasai language, ISO 639 code
Lai (surname) (賴), Chinese, sometimes romanised as Lua
Places
Tenzing-Hillary Airport (IATA code), in Lukla, Nepal
One of the Duff Islands
People
Lua (goddess), a Roman goddess
Saint Lua (died c 609)
Lua Blanco (born 1987), Brazilian actress and singer
Lua Getsinger (1871–1916)
A member of Weki Meki band
Other uses
Lua (martial art), of Hawaii
"Lua" (song), by Bright Eyes
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https://en.wikipedia.org/wiki/Zymography
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Zymography is an electrophoretic technique for the detection of hydrolytic enzymes, based on the substrate repertoire of the enzyme. Three types of zymography are used; in gel zymography, in situ zymography and in vivo zymography. For instance, gelatin embedded in a polyacrylamide gel will be digested by active gelatinases run through the gel. After Coomassie staining, areas of degradation are visible as clear bands against a darkly stained background.
Modern usage of the term zymography has been adapted to define the study and cataloging of fermented products, such as beer or wine, often by specific brewers or winemakers or within an identified category of fermentation such as with a particular strain of yeast or species of bacteria.
Zymography also refers to a collection of related, fermented products, considered as a body of work. For example, all of the beers produced by a particular brewery could collectively be referred to as its zymography.
See also Zymology or the applied science of zymography. Zymology relates to the biochemical processes of fermentation, especially the selection of fermenting yeast and bacteria in brewing, winemaking, and other fermented foods. For example, beer-making involves the application of top (ale) or bottom fermenting yeast (lager), to produce the desired variety of beer. The synthesis of the yeast can impact the flavor profile of the beer, i.e. diacetyl (taste or aroma of buttery, butterscotch).
Gel zymography
Samples are prepared in a standard, non-reducing loading buffer for SDS-PAGE. No reducing agent or boiling are necessary since these would interfere with refolding of the enzyme. A suitable substrate (e.g. gelatin or casein for protease detection) is embedded in the resolving gel during preparation of the acrylamide gel. Following electrophoresis, the SDS is removed from the gel (or zymogram) by incubation in unbuffered Triton X-100, followed by incubation in an appropriate digestion buffer, for an optimized length of t
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https://en.wikipedia.org/wiki/Online%20magazine
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An online magazine is a magazine published on the Internet, through bulletin board systems and other forms of public computer networks. One of the first magazines to convert from a print magazine format to an online only magazine was the computer magazine Datamation. Some online magazines distributed through the World Wide Web call themselves webzines. An ezine (also spelled e-zine) is a more specialized term appropriately used for small magazines and newsletters distributed by any electronic method, for example, by email. Some social groups may use the terms cyberzine and hyperzine when referring to electronically distributed resources. Similarly, some online magazines may refer to themselves as "electronic magazines", "digital magazines", or "e-magazines" to reflect their readership demographics or to capture alternative terms and spellings in online searches.
An online magazine shares some features with a blog and also with online newspapers, but can usually be distinguished by its approach to editorial control. Magazines typically have editors or editorial boards who review submissions and perform a quality control function to ensure that all material meets the expectations of the publishers (those investing time or money in its production) and the readership.
Many large print publishers now provide digital reproduction of their print magazine titles through various online services for a fee. These service providers also refer to their collections of these digital format products as online magazines, and sometimes as digital magazines.
Online magazines representing matters of interest to specialists or societies for academic subjects, science, trade, or industry are typically referred to as online journals.
Business model
Many general interest online magazines provide free access to all aspects of their online content, although some publishers have opted to require a subscription fee to access premium online article and/or multimedia content. Online magazi
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https://en.wikipedia.org/wiki/Rough%20set
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In computer science, a rough set, first described by Polish computer scientist Zdzisław I. Pawlak, is a formal approximation of a crisp set (i.e., conventional set) in terms of a pair of sets which give the lower and the upper approximation of the original set. In the standard version of rough set theory (Pawlak 1991), the lower- and upper-approximation sets are crisp sets, but in other variations, the approximating sets may be fuzzy sets.
Definitions
The following section contains an overview of the basic framework of rough set theory, as originally proposed by Zdzisław I. Pawlak, along with some of the key definitions. More formal properties and boundaries of rough sets can be found in Pawlak (1991) and cited references. The initial and basic theory of rough sets is sometimes referred to as "Pawlak Rough Sets" or "classical rough sets", as a means to distinguish from more recent extensions and generalizations.
Information system framework
Let be an information system (attribute–value system), where is a non-empty, finite set of objects (the universe) and is a non-empty, finite set of attributes such that for every . is the set of values that attribute may take. The information table assigns a value from to each attribute and object in the universe .
With any there is an associated equivalence relation :
The relation is called a -indiscernibility relation. The partition of is a family of all equivalence classes of and is denoted by (or ).
If , then and are indiscernible (or indistinguishable) by attributes from .
The equivalence classes of the -indiscernibility relation are denoted .
Example: equivalence-class structure
For example, consider the following information table:
{| class="wikitable" style="text-align:center; width:30%" border="1"
|+ Sample Information System
! Object !! !! !! !! !!
|-
!
| 1 || 2 || 0 || 1 || 1
|-
!
| 1 || 2 || 0 || 1 || 1
|-
!
| 2 || 0 || 0 || 1 || 0
|-
!
| 0 || 0 || 1 || 2 || 1
|-
!
| 2 || 1 || 0 ||
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https://en.wikipedia.org/wiki/Grothendieck%20group
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In mathematics, the Grothendieck group, or group of differences, of a commutative monoid is a certain abelian group. This abelian group is constructed from in the most universal way, in the sense that any abelian group containing a homomorphic image of will also contain a homomorphic image of the Grothendieck group of . The Grothendieck group construction takes its name from a specific case in category theory, introduced by Alexander Grothendieck in his proof of the Grothendieck–Riemann–Roch theorem, which resulted in the development of K-theory. This specific case is the monoid of isomorphism classes of objects of an abelian category, with the direct sum as its operation.
Grothendieck group of a commutative monoid
Motivation
Given a commutative monoid , "the most general" abelian group that arises from is to be constructed by introducing inverse elements to all elements of . Such an abelian group always exists; it is called the Grothendieck group of . It is characterized by a certain universal property and can also be concretely constructed from .
If does not have the cancellation property (that is, there exists and in such that and ), then the Grothendieck group cannot contain . In particular, in the case of a monoid operation denoted multiplicatively that has a zero element satisfying for every the Grothendieck group must be the trivial group (group with only one element), since one must have
for every .
Universal property
Let M be a commutative monoid. Its Grothendieck group is an abelian group K with a monoid homomorphism satisfying the following universal property: for any monoid homomorphism from M to an abelian group A, there is a unique group homomorphism such that
This expresses the fact that any abelian group A that contains a homomorphic image of M will also contain a homomorphic image of K, K being the "most general" abelian group containing a homomorphic image of M.
Explicit constructions
To construct the Grothendieck group K
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https://en.wikipedia.org/wiki/List%20of%20alternative%20set%20theories
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In mathematical logic, an alternative set theory is any of the alternative mathematical approaches to the concept of set and any alternative to the de facto standard set theory described in axiomatic set theory by the axioms of Zermelo–Fraenkel set theory.
Alternative set theories
Alternative set theories include:
Vopěnka's alternative set theory
Von Neumann–Bernays–Gödel set theory
Morse–Kelley set theory
Tarski–Grothendieck set theory
Ackermann set theory
Type theory
New Foundations
Positive set theory
Internal set theory
Naive set theory
S (set theory)
Kripke–Platek set theory
Scott–Potter set theory
Constructive set theory
Zermelo set theory
General set theory
See also
Non-well-founded set theory
Notes
Systems of set theory
Mathematics-related lists
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https://en.wikipedia.org/wiki/Multilocus%20sequence%20typing
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Multilocus sequence typing (MLST) is a technique in molecular biology for the typing of multiple loci, using DNA sequences of internal fragments of multiple housekeeping genes to characterize isolates of microbial species.
The first MLST scheme to be developed was for Neisseria meningitidis, the causative agent of meningococcal meningitis and septicaemia. Since its introduction for the research of evolutionary history, MLST has been used not only for human pathogens but also for plant pathogens.
Principle
MLST directly measures the DNA sequence variations in a set of housekeeping genes and characterizes strains by their unique allelic profiles. The principle of MLST is simple: the technique involves PCR amplification followed by DNA sequencing. Nucleotide differences between strains can be checked at a variable number of genes depending on the degree of discrimination desired.
The workflow of MLST involves: 1) data collection, 2) data analysis and 3) multilocus sequence analysis. In the data collection step, definitive identification of variation is obtained by nucleotide sequence determination of gene fragments. In the data analysis step, all unique sequences are assigned allele numbers and combined into an allelic profile and assigned a sequence type (ST). If new alleles and STs are found, they are stored in the database after verification. In the final analysis step of MLST, the relatedness of isolates are made by comparing allelic profiles. Researchers do epidemiological and phylogenetical studies by comparing STs of different clonal complexes. A huge set of data is produced during the sequencing and identification process so bioinformatic techniques are used to arrange, manage, analyze and merge all of the biological data.
To strike the balance between the acceptable identification power, time and cost for the strain typing, about seven to eight house-keeping genes are commonly used in the laboratories. Quoting Staphylococcus aureus as an example, seven hou
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https://en.wikipedia.org/wiki/Headroom%20%28audio%20signal%20processing%29
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In digital and analog audio, headroom refers to the amount by which the signal-handling capabilities of an audio system can exceed a designated nominal level. Headroom can be thought of as a safety zone allowing transient audio peaks to exceed the nominal level without damaging the system or the audio signal, e.g., via clipping. Standards bodies differ in their recommendations for nominal level and headroom.
Digital audio
In digital audio, headroom is defined as the amount by which digital full scale (FS) exceeds the nominal level in decibels (dB). The European Broadcasting Union (EBU) specifies several nominal levels and resulting headroom for different applications.
Analog audio
In analog audio, headroom can mean low-level signal capabilities as well as the amount of extra power reserve available within the amplifiers that drive the loudspeakers.
Alignment level
Alignment level is an anchor point 9 dB below the nominal level, a reference level that exists throughout the system or broadcast chain, though it may imply different voltage levels at different points in the analog chain. Typically, nominal (not alignment) level is 0 dB, corresponding to an analog sine wave of voltage of 1.23 volts RMS (+4 dBu or 3.47 volts peak to peak). In the digital realm, alignment level is −18 dBFS.
AL = analog level
SPL = sound pressure level
See also
A-weighting
Audio system measurements
Equal-loudness contour
ITU-R 468 noise weighting
Loudness war
Noise measurement
Programme levels
Rumble measurement
Weighting filter
References
Further reading
BS.1726 "Signal level of digital audio accompanying television in international programme exchange" (2005)
BS.1864 "Operational practices for loudness in the international exchange of digital television programmes" (2010)
BS.1770-3 "Algorithms to measure audio programme loudness and true-peak audio level" (2012)
External links
EBU Recommendation R68-2000
AES Preprint 4828 - Levels in Digital Audio Broadcasting
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https://en.wikipedia.org/wiki/Predistortion
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Predistortion is a technique used to improve the linearity of radio transmitter amplifiers.
Radio transmitter amplifiers in most telecommunications systems are required to be "linear", in that they must accurately reproduce the signal present at their input. An amplifier that compresses its input or has a non-linear input/output relationship causes the output signal to splatter onto adjacent radio frequencies. This causes interference on other radio channels.
There are many different ways of specifying the linearity of a power amplifier, including P1dB, Inter-modulation Distortion (IMD), AM-to-PM, spectral regrowth and Noise Power Ratio (NPR). For a truly linear system, these measures are in a sense all equivalent. That is, a power amplifier with low inter-modulation distortion will also have low spectral regrowth and low AM-to-PM distortion. Likewise there are two equivalent ways of conceptualizing how predistortion amplifiers work: correcting gain and phase distortions, or cancelling inter-modulation products. Usually one of the two conceptualizations is preferred when designing predistortion circuitry; however the end result is generally the same. A predistorter designed to correct gain and phase non-linearities will also improve IMD, while one which targets inter-modulation products will also reduce gain and phase perturbations.
When combined with the target amplifier, the linearizer produces an overall system that is more linear and reduces the amplifier's distortion. In essence, "inverse distortion" is introduced into the input of the amplifier, thereby cancelling any non-linearity the amplifier might have.
Predistortion is a cost-saving and power efficiency technique. Radio power amplifiers tend to become more non-linear as their output power increases towards their maximum rated output. Predistortion is a way to get more usable power from the amplifier, without having to build a larger, less efficient and more expensive amplifier. Another important con
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https://en.wikipedia.org/wiki/Society%20of%20Petroleum%20Engineers
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The Society of Petroleum Engineers (SPE) is a 501(c)(3) not-for-profit professional organization.
SPE provides a worldwide forum for oil and natural gas exploration and production (E&P) professionals to exchange technical knowledge and best practices. SPE manages OnePetro and PetroWiki, in addition to publishing magazines, peer-reviewed journals, and books. SPE also hosts more than 100 events each year across the globe as well as providing online tools and in-person training opportunities. SPE's technical library (OnePetro) contains more than 314,000 technical papers—products of SPE conferences and periodicals, made available to the entire industry.
SPE has offices in Dallas, Houston, Calgary, London, Dubai and Kuala Lumpur. SPE is a professional association for more than 119,000 engineers, scientists, managers, and educators. There are about 52,000 student members of SPE.
History
The history of the SPE began well before its actual establishment. During the decade after the 1901 discovery of the Spindletop field, the American Institute of Mining Engineers (AIME) saw a growing need for a forum in the booming new field of petroleum engineering. As a result, AIME formed a standing committee on oil and gas in 1913.
In 1922, the committee was expanded to become one of AIME's 10 professional divisions. The Petroleum Division of AIME continued to grow throughout the next three decades. By 1950, the Petroleum Division had become one of three separate branches of AIME, and in 1957 the Petroleum Branch of AIME was expanded once again to form a professional society.
SPE became tax-exempt in March 1985.
The first SPE Board of Directors meeting was held 6 October 1957. SPE continues to operate more than 100 events around the world.
Membership
SPE is a non-profit association for petroleum engineers. Petroleum engineers who become members of SPE gain access to several member benefits like a complimentary subscription to the Journal of Petroleum Technology, unlimited free w
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https://en.wikipedia.org/wiki/Voice%20activity%20detection
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Voice activity detection (VAD), also known as speech activity detection or speech detection, is the detection of the presence or absence of human speech, used in speech processing. The main uses of VAD are in speaker diarization, speech coding and speech recognition. It can facilitate speech processing, and can also be used to deactivate some processes during non-speech section of an audio session: it can avoid unnecessary coding/transmission of silence packets in Voice over Internet Protocol (VoIP) applications, saving on computation and on network bandwidth.
VAD is an important enabling technology for a variety of speech-based applications. Therefore, various VAD algorithms have been developed that provide varying features and compromises between latency, sensitivity, accuracy and computational cost. Some VAD algorithms also provide further analysis, for example whether the speech is voiced, unvoiced or sustained. Voice activity detection is usually independent of language.
It was first investigated for use on time-assignment speech interpolation (TASI) systems.
Algorithm overview
The typical design of a VAD algorithm is as follows:
There may first be a noise reduction stage, e.g. via spectral subtraction.
Then some features or quantities are calculated from a section of the input signal.
A classification rule is applied to classify the section as speech or non-speech – often this classification rule finds when a value exceeds a certain threshold.
There may be some feedback in this sequence, in which the VAD decision is used to improve the noise estimate in the noise reduction stage, or to adaptively vary the threshold(s). These feedback operations improve the VAD performance in non-stationary noise (i.e. when the noise varies a lot).
A representative set of recently published VAD methods formulates the decision rule on a frame by frame basis using instantaneous measures of the divergence distance between speech and noise. The different measures which
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https://en.wikipedia.org/wiki/ECRYPT
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ECRYPT (European Network of Excellence in Cryptology) was a 4-year European research initiative launched on 1 February 2004 with the stated objective of promoting the collaboration of European researchers in information security, and especially in cryptology and digital watermarking.
ECRYPT listed five core research areas, termed "virtual laboratories": symmetric key algorithms (STVL), public key algorithms (AZTEC), protocol (PROVILAB), secure and efficient implementations (VAMPIRE) and watermarking (WAVILA).
In August 2008 the network started another 4-year phase as ECRYPT II.
ECRYPT II products
Yearly report on algorithms and key lengths
During the project, algorithms and key lengths were evaluated yearly. The most recent of these documents is dated 30 September 2012.
Key sizes
Considering the budget of a large intelligence agency to be about US$300 million for a single ASIC machine, the recommended minimum key size is 84 bits, which would give protection for a few months. In practice, most commonly used algorithms have key sizes of 128 bits or more, providing sufficient security also in the case that the chosen algorithm is slightly weakened by cryptanalysis.
Different kinds of keys are compared in the document (e.g. RSA keys vs. EC keys). This "translation table" can be used to roughly equate keys of other types of algorithms with symmetric encryption algorithms. In short, 128 bit symmetric keys are said to be equivalent to 3248 bits RSA keys or 256-bit EC keys. Symmetric keys of 256 bits are roughly equivalent to 15424 bit RSA keys or 512 bit EC keys. Finally 2048 bit RSA keys are said to be equivalent to 103 bit symmetric keys.
Among key sizes, 8 security levels are defined, from the lowest "Attacks possible in real-time by individuals" (level 1, 32 bits) to "Good for the foreseeable future, also against quantum computers unless Shor's algorithm applies" (level 8, 256 bits). For general long-term protection (30 years), 128 bit keys are recommended (
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https://en.wikipedia.org/wiki/MAC%20flooding
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In computer networking, a media access control attack or MAC flooding is a technique employed to compromise the security of network switches. The attack works by forcing legitimate MAC table contents out of the switch and forcing a unicast flooding behavior potentially sending sensitive information to portions of the network where it is not normally intended to go.
Attack method
Switches maintain a MAC table that maps individual MAC addresses on the network to the physical ports on the switch. This allows the switch to direct data out of the physical port where the recipient is located, as opposed to indiscriminately broadcasting the data out of all ports as an Ethernet hub does. The advantage of this method is that data is bridged exclusively to the network segment containing the computer that the data is specifically destined for.
In a typical MAC flooding attack, a switch is fed many Ethernet frames, each containing different source MAC addresses, by the attacker. The intention is to consume the limited memory set aside in the switch to store the MAC address table.
The effect of this attack may vary across implementations, however the desired effect (by the attacker) is to force legitimate MAC addresses out of the MAC address table, causing significant quantities of incoming frames to be flooded out on all ports. It is from this flooding behavior that the MAC flooding attack gets its name.
After launching a successful MAC flooding attack, a malicious user can use a packet analyzer to capture sensitive data being transmitted between other computers, which would not be accessible were the switch operating normally. The attacker may also follow up with an ARP spoofing attack which will allow them to retain access to privileged data after switches recover from the initial MAC flooding attack.
MAC flooding can also be used as a rudimentary VLAN hopping attack.
Counter measures
To prevent MAC flooding attacks, network operators usually rely on the presence of
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https://en.wikipedia.org/wiki/Sotolon
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Sotolon (also known as sotolone) is a lactone and an extremely powerful aroma compound, with the typical smell of fenugreek or curry at high concentrations and maple syrup, caramel, or burnt sugar at lower concentrations. Sotolon is the major aroma and flavor component of fenugreek seed and lovage, and is one of several aromatic and flavor components of artificial maple syrup. It is also present in molasses, aged rum, aged sake and white wine, flor sherry, roast tobacco, and dried fruiting bodies of the mushroom Lactarius helvus. Sotolon can pass through the body relatively unchanged, and consumption of foods high in sotolon, such as fenugreek, can impart a maple syrup aroma to one's sweat and urine. In some individuals with the genetic disorder maple syrup urine disease, it is spontaneously produced in their bodies and excreted in their urine, leading to the disease's characteristic smell.
This molecule is thought to be responsible for the mysterious maple syrup smell that has occasionally wafted over Manhattan since 2005. Sotolon was first isolated in 1975 from the herb fenugreek. The compound was named in 1980 when it was found to be responsible for the flavor of raw cane sugar: soto- means "raw sugar" in Japanese and -olon signifies that the molecule is an enol lactone.
Several aging-derived compounds have been pointed out as playing an important role on the aroma of fortified wines; however, sotolon (3-hydroxy-4,5-dimethyl-2(5H)-furanone) is recognized as being the key odorant and has also been classified as a potential aging marker of these type of wines. This chiral lactone is a powerful odorant, which can impart a nutty, caramel, curry, or rancid odor, depending on its concentration and enantiomeric distribution. Despite being pointed out as a key odorant of other fortified wines, the researchers’ attention has also been directed to its off-flavor character, associated to the premature oxidative aging of young dry white wines, overlapping the expected fr
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https://en.wikipedia.org/wiki/Quadratic%20assignment%20problem
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The quadratic assignment problem (QAP) is one of the fundamental combinatorial optimization problems in the branch of optimization or operations research in mathematics, from the category of the facilities location problems first introduced by Koopmans and Beckmann.
The problem models the following real-life problem:
There are a set of n facilities and a set of n locations. For each pair of locations, a distance is specified and for each pair of facilities a weight or flow is specified (e.g., the amount of supplies transported between the two facilities). The problem is to assign all facilities to different locations with the goal of minimizing the sum of the distances multiplied by the corresponding flows.
Intuitively, the cost function encourages facilities with high flows between each other to be placed close together.
The problem statement resembles that of the assignment problem, except that the cost function is expressed in terms of quadratic inequalities, hence the name.
Formal mathematical definition
The formal definition of the quadratic assignment problem is as follows:
Given two sets, P ("facilities") and L ("locations"), of equal size, together with a weight function w : P × P → R and a distance function d : L × L → R. Find the bijection f : P → L ("assignment") such that the cost function:
is minimized.
Usually weight and distance functions are viewed as square real-valued matrices, so that the cost function is written down as:
In matrix notation:
where is the set of permutation matrices, is the weight matrix and is the distance matrix.
Computational complexity
The problem is NP-hard, so there is no known algorithm for solving this problem in polynomial time, and even small instances may require long computation time. It was also proven that the problem does not have an approximation algorithm running in polynomial time for any (constant) factor, unless P = NP. The travelling salesman problem (TSP) may be seen as a special case of QA
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https://en.wikipedia.org/wiki/Food%20technology
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Food technology is a branch of food science that addresses the production, preservation, quality control and research and development of food products.
Early scientific research into food technology concentrated on food preservation. Nicolas Appert's development in 1810 of the canning process was a decisive event. The process wasn't called canning then and Appert did not really know the principle on which his process worked, but canning has had a major impact on food preservation techniques.
Louis Pasteur's research on the spoilage of wine and his description of how to avoid spoilage in 1864, was an early attempt to apply scientific knowledge to food handling. Besides research into wine spoilage, Pasteur researched the production of alcohol, vinegar, wines and beer, and the souring of milk. He developed pasteurization – the process of heating milk and milk products to destroy food spoilage and disease-producing organisms. In his research into food technology, Pasteur became the pioneer into bacteriology and of modern preventive medicine.
Developments
Developments in food technology have contributed greatly to the food supply and have changed our world. Some of these developments are:
Instantized Milk Powder – Instant milk powder has become the basis for a variety of new products that are rehydratable. This process increases the surface area of the powdered product by partially rehydrating spray-dried milk powder.
Freeze-drying – The first application of freeze drying was most likely in the pharmaceutical industry; however, a successful large-scale industrial application of the process was the development of continuous freeze drying of coffee.
High-Temperature Short Time Processing – These processes, for the most part, are characterized by rapid heating and cooling, holding for a short time at a relatively high temperature and filling aseptically into sterile containers.
Decaffeination of Coffee and Tea – Decaffeinated coffee and tea was first developed on
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