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https://en.wikipedia.org/wiki/113%20%28number%29 | 113 (one hundred [and] thirteen) is the natural number following 112 and preceding 114.
Mathematics
113 is the 30th prime number (following 109 and preceding 127), so it can only be divided by one and itself. 113 is a Sophie Germain prime, an emirp, an isolated prime, a Chen prime and a Proth prime as it is a prime number of the form 113 is also an Eisenstein prime with no imaginary part and real part of the form . In decimal, this prime is a primeval number and a permutable prime with 131 and 311.
113 is a highly cototient number and a centered square number.
113 is the denominator of 355/113, an accurate approximation to .
See also
113 (disambiguation)
A113 is a Pixar recurring inside joke or Easter Egg, e.g.: (WALL-E) = (W-A113).
References
Wells, D. The Penguin Dictionary of Curious and Interesting Numbers London: Penguin Group. (1987): 134
Integers |
https://en.wikipedia.org/wiki/114%20%28number%29 | 114 (one hundred [and] fourteen) is the natural number following 113 and preceding 115.
In mathematics
114 is an abundant number, a sphenic number and a Harshad number. It is the sum of the first four hyperfactorials, including H(0). At 114, the Mertens function sets a new low of -6, a record that stands until 197.
114 is the smallest positive integer* which has yet to be represented as a3 + b3 + c3, where a, b, and c are integers. It is conjectured that 114 can be represented this way. (*Excluding integers of the form 9k ± 4, for which solutions are known not to exist.)
There is no answer to the equation φ(x) = 114, making 114 a nontotient.
114 appears in the Padovan sequence, preceded by the terms 49, 65, 86 (it is the sum of the first two of these).
114 is a repdigit in base 7 (222).
In religion
There are 114 chapters, or surahs, in the Quran.
There are 114 sayings in The Gospel of Thomas.
See also
114 (disambiguation)
References
Integers |
https://en.wikipedia.org/wiki/100 | 100 or one hundred (Roman numeral: C) is the natural number following 99 and preceding 101.
In mathematics
100 is the square of 10 (in scientific notation it is written as 102). The standard SI prefix for a hundred is "hecto-".
100 is the basis of percentages (per cent meaning "per hundred" in Latin), with 100% being a full amount.
100 is a Harshad number in decimal, and also in base-four, a base in-which it is also a self-descriptive number.
100 is the sum of the first nine prime numbers, from 2 through 23. It is also divisible by the number of primes below it, 25.
100 cannot be expressed as the difference between any integer and the total of coprimes below it, making it a noncototient.
100 has a reduced totient of 20, and an Euler totient of 40. A totient value of 100 is obtained from four numbers: 101, 125, 202, and 250.
100 can be expressed as a sum of some of its divisors, making it a semiperfect number. The geometric mean of its nine divisors is 10.
100 is the sum of the cubes of the first four positive integers (100 = 13 + 23 + 33 + 43). This is related by Nicomachus's theorem to the fact that 100 also equals the square of the sum of the first four positive integers: .
100 = 26 + 62, thus 100 is the seventh Leyland number. 100 is also the seventeenth Erdős–Woods number, and the fourth 18-gonal number.
The 100th prime number is 541, which returns for the Mertens function. It is the 10th star number (whose digit sum also adds to 10 in decimal).
There are exactly 100 prime numbers in base-ten whose digits are in strictly ascending order (e.g. 239, 2357 etc.). The last such prime number is 23456789, which contains eight consecutive integers as digits.
In science
One hundred is the atomic number of fermium, an actinide and the last of the heavy metals that can be created through neutron bombardment.
On the Celsius scale, 100 degrees is the boiling temperature of pure water at sea level.
The Kármán line lies at an altitude of 100 kilometres above th |
https://en.wikipedia.org/wiki/1001%20%28number%29 | 1001 is the natural number following 1000 and followed by 1002.
In mathematics
One thousand and one is a sphenic number, a pentagonal number, a pentatope number and the first four-digit palindromic number. Scheherazade numbers always have 1001 as a factor.
Divisibility by 7, 11 and 13
Two properties of 1001 are the basis of a divisibility test for 7, 11 and 13. The method is along the same lines as the divisibility rule for 11 using the property 10 ≡ -1 (mod 11). The two properties of 1001 are
1001 = 7 × 11 × 13 in prime factors
103 ≡ -1 (mod 1001)
The method simultaneously tests for divisibility by any of the factors of 1001. First, the digits of the number being tested are grouped in blocks of three. The odd numbered groups are summed. The sum of the even numbered groups is then subtracted from the sum of the odd numbered groups. The test number is divisible by 7, 11 or 13 iff the result of the summation is divisible by 7, 11 or 13 respectively.
Example:
Number under test, N = 22 872 563 219
Sum of odd groups, So = 219 + 872 = 1091
Sum of even groups, Se = 563 + 22 = 585
Total sum, S = So - Se = 1091 - 585 = 506
506 = 46 × 11
Since 506 is divisible by 11 then N is also divisible by 11. If the total sum is still too large to conveniently test for divisibility, and is longer than three digits, then the algorithm can be repeated to obtain a smaller number.
In other fields
In The Book of One Thousand and One Nights, Scheherazade tells her husband the king a new story every night for 1,001 nights, staving off her execution. From this, 1001 is sometimes used as a generic term for "a very large number", starting with a large number (1000) and going beyond it:
1001 uses for...
1001 ways to...
In Arabic, this is usually phrased as "one thousand things and one thing", e.g.:
The Book of One Thousand and One Nights, in Arabic Alf layla wa layla (), literally "One thousand nights and a night".
1001 was the name of a popular British detergent in the |
https://en.wikipedia.org/wiki/Copy-on-write | Copy-on-write (COW), sometimes referred to as implicit sharing or shadowing, is a resource-management technique used in computer programming to efficiently implement a "duplicate" or "copy" operation on modifiable resources. If a resource is duplicated but not modified, it is not necessary to create a new resource; the resource can be shared between the copy and the original. Modifications must still create a copy, hence the technique: the copy operation is deferred until the first write. By sharing resources in this way, it is possible to significantly reduce the resource consumption of unmodified copies, while adding a small overhead to resource-modifying operations.
In virtual memory management
Copy-on-write finds its main use in sharing the virtual memory of operating system processes, in the implementation of the fork system call. Typically, the process does not modify any memory and immediately executes a new process, replacing the address space entirely. Thus, it would be wasteful to copy all of the process's memory during a fork, and instead the copy-on-write technique is used.
Copy-on-write can be implemented efficiently using the page table by marking certain pages of memory as read-only and keeping a count of the number of references to the page. When data is written to these pages, the operating-system kernel intercepts the write attempt and allocates a new physical page, initialized with the copy-on-write data, although the allocation can be skipped if there is only one reference. The kernel then updates the page table with the new (writable) page, decrements the number of references, and performs the write. The new allocation ensures that a change in the memory of one process is not visible in another's.
The copy-on-write technique can be extended to support efficient memory allocation by having a page of physical memory filled with zeros. When the memory is allocated, all the pages returned refer to the page of zeros and are all marked copy-on-wr |
https://en.wikipedia.org/wiki/Sodium%20nitrite | Sodium nitrite is an inorganic compound with the chemical formula NaNO2. It is a white to slightly yellowish crystalline powder that is very soluble in water and is hygroscopic. From an industrial perspective, it is the most important nitrite salt. It is a precursor to a variety of organic compounds, such as pharmaceuticals, dyes, and pesticides, but it is probably best known as a food additive used in processed meats and (in some countries) in fish products.
Uses
Industrial chemistry
The main use of sodium nitrite is for the industrial production of organonitrogen compounds. It is a reagent for conversion of amines into diazo compounds, which are key precursors to many dyes, such as diazo dyes. Nitroso compounds are produced from nitrites. These are used in the rubber industry.
It is used in a variety of metallurgical applications, for phosphatizing and detinning.
Sodium nitrite is an effective corrosion inhibitor and is used as an additive in industrial greases, as an aqueous solution in closed loop cooling systems, and in a molten state as a heat transfer medium.
Food additive and preservative
Sodium nitrite is used to speed up the curing of meat, inhibit the germination of Clostridium botulinum spores, and also impart an attractive pink color. Nitrite reacts with the meat myoglobin to cause color changes, first converting to nitrosomyoglobin (bright red), then, on heating, to nitrosohemochrome (a pink pigment).
Historically, salt has been used for the preservation of meat. The salt-preserved meat product was usually brownish-gray in color. When sodium nitrite is added with the salt, the meat develops a red, then pink color, which is associated with cured meats such as ham, bacon, hot dogs, and bologna.
In the early 1900s, irregular curing was commonplace. This led to further research surrounding the use of sodium nitrite as an additive in food, standardizing the amount present in foods to minimize the amount needed while maximizing its food additive rol |
https://en.wikipedia.org/wiki/Virtual%20hosting | Virtual hosting is a method for hosting multiple domain names (with separate handling of each name) on a single server (or pool of servers). This allows one server to share its resources, such as memory and processor cycles, without requiring all services provided to use the same host name. The term virtual hosting is usually used in reference to web servers but the principles do carry over to other Internet services.
One widely used application is shared web hosting. The price for shared web hosting is lower than for a dedicated web server because many customers can be hosted on a single server. It is also very common for a single entity to want to use multiple names on the same machine so that the names can reflect services offered rather than where those services happen to be hosted.
There are two main types of virtual hosting, name-based and IP-based. Name-based virtual hosting uses the host name presented by the client. This saves IP addresses and the associated administrative overhead but the protocol being served must supply the host name at an appropriate point. In particular, there are significant difficulties using name-based virtual hosting with SSL/TLS. IP-based virtual hosting uses a separate IP address for each host name, and it can be performed with any protocol but requires a dedicated IP address per domain name served. Port-based virtual hosting is also possible in principle but is rarely used in practice because it is unfriendly to users.
Name-based and IP-based virtual hosting can be combined: a server may have multiple IP addresses and serve multiple names on some or all of those IP addresses. This technique can be useful when using SSL/TLS with wildcard certificates. For example, if a server operator had two certificates, one for *.example.com and one for *.example.net, the operator could serve foo.example.com and bar.example.com off the same IP address but would need a separate IP address for baz.example.net.
Name-based
Name-based virtual h |
https://en.wikipedia.org/wiki/Hygiene%20hypothesis | In medicine, the hygiene hypothesis states that early childhood exposure to particular microorganisms (such as the gut flora and helminth parasites) protects against allergies by strengthening the immune system. In particular, a lack of such exposure is thought to lead to poor immune tolerance. The time period for exposure begins before birth and ends at school age.
While early versions of the hypothesis referred to microorganism exposure in general, later versions apply to a specific set of microbes that have co-evolved with humans. The updates have been given various names, including the microbiome depletion hypothesis, the microflora hypothesis, and the "old friends" hypothesis. There is a significant amount of evidence supporting the idea that lack of exposure to these microbes is linked to allergies or other conditions, although it is still rejected by many scientists.
The term "hygiene hypothesis" has been described as a misnomer because people incorrectly interpret it as referring to their own cleanliness. Having worse personal hygiene, such as not washing hands before eating, only increases the risk of infection without affecting the risk of allergies or immune disorders. Hygiene is essential for protecting vulnerable populations such as the elderly from infections, preventing the spread of antibiotic resistance, and combating emerging infectious diseases such as Ebola or COVID-19. The hygiene hypothesis does not suggest that having more infections during childhood would be an overall benefit.
Overview
The idea of a link between parasite infection and immune disorders was first suggested in 1968 before the advent of large scale dna sequencing techniques. The original formulation of the hygiene hypothesis dates from 1989, when David Strachan proposed that lower incidence of infection in early childhood could be an explanation for the rise in allergic diseases such as asthma and hay fever during the 20th century.
The hygiene hypothesis has also been exp |
https://en.wikipedia.org/wiki/List%20of%20probability%20topics | This is a list of probability topics.
It overlaps with the (alphabetical) list of statistical topics. There are also the outline of probability and catalog of articles in probability theory. For distributions, see List of probability distributions. For journals, see list of probability journals. For contributors to the field, see list of mathematical probabilists and list of statisticians.
General aspects
Probability
Randomness, Pseudorandomness, Quasirandomness
Randomization, hardware random number generator
Random number generation
Random sequence
Uncertainty
Statistical dispersion
Observational error
Equiprobable
Equipossible
Average
Probability interpretations
Markovian
Statistical regularity
Central tendency
Bean machine
Relative frequency
Frequency probability
Maximum likelihood
Bayesian probability
Principle of indifference
Credal set
Cox's theorem
Principle of maximum entropy
Information entropy
Urn problems
Extractor
Free probability
Exotic probability
Schrödinger method
Empirical measure
Glivenko–Cantelli theorem
Zero–one law
Kolmogorov's zero–one law
Hewitt–Savage zero–one law
Law of truly large numbers
Littlewood's law
Infinite monkey theorem
Littlewood–Offord problem
Inclusion–exclusion principle
Impossible event
Information geometry
Talagrand's concentration inequality
Foundations of probability theory
Probability theory
Probability space
Sample space
Standard probability space
Random element
Random compact set
Dynkin system
Probability axioms
Normalizing constant
Event (probability theory)
Complementary event
Elementary event
Mutually exclusive
Boole's inequality
Probability density function
Cumulative distribution function
Law of total cumulance
Law of total expectation
Law of total probability
Law of total variance
Almost surely
Cox's theorem
Bayesianism
Prior probability
Posterior probability
Borel's paradox
Bertrand's paradox
Coherence (philosophical gambling strategy)
Dutch |
https://en.wikipedia.org/wiki/Mahler%27s%20theorem | In mathematics, Mahler's theorem, introduced by , expresses any continuous p-adic function as an infinite series of certain special polynomials. It is the p-adic counterpart to the Stone-Weierstrass theorem for continuous real-valued functions on a closed interval.
Statement
Let be the forward difference operator. Then for any p-adic function , Mahler's theorem states that is continuous if and only if its Newton series converges everywhere to , so that for all we have
where
is the th binomial coefficient polynomial. Here, the th forward difference is computed by the binomial transform, so thatMoreover, we have that is continuous if and only if the coefficients in as .
It is remarkable that as weak an assumption as continuity is enough in the p-adic setting to establish convergence of Newton series. By contrast, Newton series on the field of complex numbers are far more tightly constrained, and require Carlson's theorem to hold.
References
Factorial and binomial topics
Theorems in analysis |
https://en.wikipedia.org/wiki/American%20Association%20of%20State%20Highway%20and%20Transportation%20Officials | The American Association of State Highway and Transportation Officials (AASHTO) is a standards setting body which publishes specifications, test protocols, and guidelines that are used in highway design and construction throughout the United States. Despite its name, the association represents not only highways but air, rail, water, and public transportation as well.
Although AASHTO sets transportation standards and policy for the United States as a whole, AASHTO is not an agency of the federal government; rather it is an organization of the states themselves. Policies of AASHTO are not federal laws or policies, but rather are ways to coordinate state laws and policies in the field of transportation.
Purpose
The American Association of State Highway Officials (AASHO) was founded on December 12, 1914. Its name was changed to American Association of State Highway and Transportation Officials on November 13, 1973. The name change reflects a broadened scope to cover all modes of transportation, although most of its activities are still specific to highways.
While AASHTO is not a government body, it does possess quasi-governmental powers in the sense that the organizations that supply its members customarily obey most AASHTO decisions.
Membership
The voting membership of AASHTO consists of the Department of Transportation of each state in the United States, as well as those of Puerto Rico and the District of Columbia.
The United States Department of Transportation, some U.S. cities, counties, and toll-road operators, most Canadian provinces as well as the Hong Kong Highways Department, the Turkish Ministry of Public Works and Settlement, and the Nigerian Association of Public Highway and Transportation Officials have non-voting associate memberships.
Publications
Some noteworthy AASHTO publications are:
A Policy on Geometric Design of Highways and Streets, often called "The Green Book" because of the color of its cover. This book covers the functional design of |
https://en.wikipedia.org/wiki/Cauchy%20principal%20value | In mathematics, the Cauchy principal value, named after Augustin Louis Cauchy, is a method for assigning values to certain improper integrals which would otherwise be undefined. In this method, a singularity on an integral interval is avoided by limiting the integral interval to the singularity (so the singularity is not covered by the integral).
Formulation
Depending on the type of singularity in the integrand , the Cauchy principal value is defined according to the following rules:
In some cases it is necessary to deal simultaneously with singularities both at a finite number and at infinity. This is usually done by a limit of the form
In those cases where the integral may be split into two independent, finite limits,
and
then the function is integrable in the ordinary sense. The result of the procedure for principal value is the same as the ordinary integral; since it no longer matches the definition, it is technically not a "principal value".
The Cauchy principal value can also be defined in terms of contour integrals of a complex-valued function with with a pole on a contour . Define to be that same contour, where the portion inside the disk of radius around the pole has been removed. Provided the function is integrable over no matter how small becomes, then the Cauchy principal value is the limit:
In the case of Lebesgue-integrable functions, that is, functions which are integrable in absolute value, these definitions coincide with the standard definition of the integral.
If the function is meromorphic, the Sokhotski–Plemelj theorem relates the principal value of the integral over with the mean-value of the integrals with the contour displaced slightly above and below, so that the residue theorem can be applied to those integrals.
Principal value integrals play a central role in the discussion of Hilbert transforms.
Distribution theory
Let be the set of bump functions, i.e., the space of smooth functions with compact support on the real |
https://en.wikipedia.org/wiki/Taxicab%20geometry | A taxicab geometry or a Manhattan geometry is a geometry whose usual distance function or metric of Euclidean geometry is replaced by a new metric in which the distance between two points is the sum of the absolute differences of their Cartesian coordinates. The taxicab metric is also known as rectilinear distance, L1 distance, L1 distance or norm (see Lp space), snake distance, city block distance, Manhattan distance or Manhattan length. The latter names refer to the rectilinear street layout on the island of Manhattan, where the shortest path a taxi travels between two points is the sum of the absolute values of distances that it travels on avenues and on streets.
The geometry has been used in regression analysis since the 18th century, and is often referred to as LASSO. The geometric interpretation dates to non-Euclidean geometry of the 19th century and is due to Hermann Minkowski.
In , the taxicab distance between two points and is . That is, it is the sum of the absolute values of the differences in both coordinates.
Formal definition
The taxicab distance, , between two vectors in an n-dimensional real vector space with fixed Cartesian coordinate system, is the sum of the lengths of the projections of the line segment between the points onto the coordinate axes. More formally,For example, in , the taxicab distance between and is
History
The L1 metric was used in regression analysis in 1757 by Roger Joseph Boscovich. The geometric interpretation dates to the late 19th century and the development of non-Euclidean geometries, notably by Hermann Minkowski and his Minkowski inequality, of which this geometry is a special case, particularly used in the geometry of numbers, . The formalization of Lp spaces is credited to .
Properties
Taxicab distance depends on the rotation of the coordinate system, but does not depend on its reflection about a coordinate axis or its translation. Taxicab geometry satisfies all of Hilbert's axioms (a formalization of Euc |
https://en.wikipedia.org/wiki/Alien%20Breed%20%28video%20game%29 | Alien Breed is a top down run and gun video game released in 1991 by Team17 for the Amiga and later in 1993 by MicroLeague for MS-DOS. The game is the first in the Alien Breed series.Alien Breed is based on the Alien films, specifically Aliens, and also on the 8-bit-era games Laser Squad and Paradroid as well as the Gauntlet arcade game.
Gameplay
Players must find the lift down to the next level, occasionally setting the self-destruct sequence to blow up the level above them. The players collect or purchase a variety of weapons from the space station's computer terminals. In some versions of the game, these so-called Intex terminals provide additional features such as a clone of the classic video game Pong. Credits found on the ground have to be saved for these weapons and other enhancements, each giving the players an edge over the gradually more and more powerful alien forces. In advanced levels, players are occasionally trapped in enclosed spaces with huge boss aliens.
Release
Team17 made an "intro disk" available, containing a short animated introductory sequence with on-screen narration which follows events leading into the start of the game. After the introduction is finished, the player is prompted for disk one of the game, effectively making the introduction disk "disk zero". Team17 produced a similar introduction disk for Superfrog, animated by Eric W. Schwartz, although this was included with the retail edition of the game.
Reception
Amiga Alien Breed was released to generally favorable reviews. CU Amiga wrote that "Team17 have come up with a winner".
MS-DOS
The MS-DOS port's reception was mixed. PC Gamer US described the gameplay's variety as lacking and the sound effects as "shallow and tinny", with problems using the Pro Audio Spectrum sound card to be expected, but favorably compared it to Sega Genesis games and called it a "solid shooter [with] plenty of high-octane fun." Computer Gaming World criticized the "asinine" copy protection, bu |
https://en.wikipedia.org/wiki/IEEE%20802.20 | IEEE 802.20 or Mobile Broadband Wireless Access (MBWA) was a specification by the standard association of the Institute of Electrical and Electronics Engineers (IEEE) for mobile broadband networks. The main standard was published in 2008. MBWA is no longer being actively developed.
This wireless broadband technology is also known and promoted as iBurst (or HC-SDMA, High Capacity Spatial Division Multiple Access). It was originally developed by ArrayComm and optimizes the use of its bandwidth with the help of smart antennas. Kyocera is the manufacturer of iBurst devices.
Description
iBurst is a mobile broadband wireless access system that was first developed by ArrayComm, and announced with partner Sony in April 2000.
It was adopted as the High Capacity – Spatial Division Multiple Access (HC-SDMA) radio interface standard (ATIS-0700004-2005) by the Alliance for Telecommunications Industry Solutions (ATIS).
The standard was prepared by ATIS’ Wireless Technology and Systems Committee's Wireless Wideband Internet Access subcommittee and accepted as an American National Standard in 2005.
HC-SDMA was announced as considered by ISO TC204 WG16 for the continuous communications standards architecture, known as Communications, Air-interface, Long and Medium range (CALM), which ISO is developing for intelligent transport systems (ITS). ITS may include applications for public safety, network congestion management during traffic incidents, automatic toll booths, and more. An official liaison was established between WTSC and ISO TC204 WG16 for this in 2005.
The HC-SDMA interface provides wide-area broadband wireless data-connectivity for fixed, portable and mobile computing devices and appliances. The protocol is designed to be implemented with smart antenna array techniques (called MIMO for multiple-input multiple-output) to substantially improve the radio frequency (RF) coverage, capacity and performance for the system.
In January 2006, the IEEE 802.20 Mobile Broadband W |
https://en.wikipedia.org/wiki/Kissing%20number | In geometry, the kissing number of a mathematical space is defined as the greatest number of non-overlapping unit spheres that can be arranged in that space such that they each touch a common unit sphere. For a given sphere packing (arrangement of spheres) in a given space, a kissing number can also be defined for each individual sphere as the number of spheres it touches. For a lattice packing the kissing number is the same for every sphere, but for an arbitrary sphere packing the kissing number may vary from one sphere to another.
Other names for kissing number that have been used are Newton number (after the originator of the problem), and contact number.
In general, the kissing number problem seeks the maximum possible kissing number for n-dimensional spheres in (n + 1)-dimensional Euclidean space. Ordinary spheres correspond to two-dimensional closed surfaces in three-dimensional space.
Finding the kissing number when centers of spheres are confined to a line (the one-dimensional case) or a plane (two-dimensional case) is trivial. Proving a solution to the three-dimensional case, despite being easy to conceptualise and model in the physical world, eluded mathematicians until the mid-20th century. Solutions in higher dimensions are considerably more challenging, and only a handful of cases have been solved exactly. For others investigations have determined upper and lower bounds, but not exact solutions.
Known greatest kissing numbers
One dimension
In one dimension, the kissing number is 2:
Two dimensions
In two dimensions, the kissing number is 6:
Proof: Consider a circle with center C that is touched by circles with centers C1, C2, .... Consider the rays C Ci. These rays all emanate from the same center C, so the sum of angles between adjacent rays is 360°.
Assume by contradiction that there are more than six touching circles. Then at least two adjacent rays, say C C1 and C C2, are separated by an angle of less than 60°. The segments C Ci have the s |
https://en.wikipedia.org/wiki/Long%20Duration%20Exposure%20Facility | NASA's Long Duration Exposure Facility, or LDEF (pronounced "eldef"), was a cylindrical facility designed to provide long-term experimental data on the outer space environment and its effects on space systems, materials, operations and selected spores' survival. It was placed in low Earth orbit by in April 1984. The original plan called for the LDEF to be retrieved in March 1985, but after a series of delays it was eventually returned to Earth by in January 1990.
It successfully carried science and technology experiments for about 5.7 years that have revealed a broad and detailed collection of space environmental data. LDEF's 69 months in space provided scientific data on the long-term effects of space exposure on materials, components and systems that has benefited NASA spacecraft designers to this day.
History
Researchers identified the potential of the planned Space Shuttle to deliver a payload to space, leave it there for a long-term exposure to the harsh outer space environment, and retrieve it for analysis on a separate mission. The LDEF concept evolved from a spacecraft proposed by NASA's Langley Research Center in 1970 to study the meteoroid environment, the Meteoroid and Exposure Module (MEM). The project was approved in 1974 and LDEF was built at NASA's Langley Research Center.
LDEF was intended to be reused, and redeployed with new experiments, perhaps every 18 months. but after the unintended extension of mission 1 the structure itself was treated as an experiment and intensively studied before being placed into storage.
Launch and deployment
The STS-41-C crew of deployed LDEF on April 7, 1984, into a nearly circular orbit at an altitude of 257 nautical miles.
Design and structure
The LDEF structure shape was a 12 sided prism (to fit the shuttle orbiter payload bay), and made entirely from stainless steel. There were 5 or 6 experiments on each of the 12 long sides and a few more on the ends. It was designed to fly with one end facing earth and th |
https://en.wikipedia.org/wiki/Omega%20constant | The omega constant is a mathematical constant defined as the unique real number that satisfies the equation
It is the value of , where is Lambert's function. The name is derived from the alternate name for Lambert's function, the omega function. The numerical value of is given by
.
.
Properties
Fixed point representation
The defining identity can be expressed, for example, as
or
as well as
Computation
One can calculate iteratively, by starting with an initial guess , and considering the sequence
This sequence will converge to as approaches infinity. This is because is an attractive fixed point of the function .
It is much more efficient to use the iteration
because the function
in addition to having the same fixed point, also has a derivative that vanishes there. This guarantees quadratic convergence; that is, the number of correct digits is roughly doubled with each iteration.
Using Halley's method, can be approximated with cubic convergence (the number of correct digits is roughly tripled with each iteration): (see also ).
Integral representations
An identity due to Victor Adamchik is given by the relationship
Other relations due to Mező
and Kalugin-Jeffrey-Corless
are:
The latter two identities can be extended to other values of the function (see also ).
Transcendence
The constant is transcendental. This can be seen as a direct consequence of the Lindemann–Weierstrass theorem. For a contradiction, suppose that is algebraic. By the theorem, is transcendental, but , which is a contradiction. Therefore, it must be transcendental.
References
External links
Omega
Articles containing proofs
Real transcendental numbers |
https://en.wikipedia.org/wiki/Object%20Constraint%20Language | The Object Constraint Language (OCL) is a declarative language describing rules applying to Unified Modeling Language (UML) models developed at IBM and is now part of the UML standard. Initially, OCL was merely a formal specification language extension for UML. OCL may now be used with any Meta-Object Facility (MOF) Object Management Group (OMG) meta-model, including UML. The Object Constraint Language is a precise text language that provides constraint and object query expressions on any MOF model or meta-model that cannot otherwise be expressed by diagrammatic notation. OCL is a key component of the new OMG standard recommendation for transforming models, the Queries/Views/Transformations (QVT) specification.
Description
OCL is a descendant of Syntropy, a second-generation object-oriented analysis and design method. The OCL 1.4 definition specified a constraint language. In OCL 2.0, the definition has been extended to include general object query language definitions.
OCL statements are constructed in four parts:
a context that defines the limited situation in which the statement is valid
a property that represents some characteristics of the context (e.g., if the context is a class, a property might be an attribute)
an operation (e.g., arithmetic, set-oriented) that manipulates or qualifies a property, and
keywords (e.g., if, then, else, and, or, not, implies) that are used to specify conditional expressions.
Relation
OCL and UML
OCL supplements UML by providing expressions that have neither the ambiguities of natural language nor the inherent difficulty of using complex mathematics. OCL is also a navigation language for graph-based models.
OCL and MOF
OCL makes a Meta-Object Facility model more precise by associating assertions with its meta-elements.
OCL and QVT
Of particular importance to Model Driven Engineering (MDE) or model-driven architecture is the notion of Model transformation. The OMG has defined a specific standard for model transfor |
https://en.wikipedia.org/wiki/Green%20manure | In agriculture, a green manure is a crop specifically cultivated to be incorporated into the soil while still green. Typically, the green manure's biomass is incorporated with a plow or disk, as is often done with (brown) manure. The primary goal is to add organic matter to the soil for its benefits. Green manuring is often used with legume crops to add nitrogen to the soil for following crops, especially in organic farming, but is also used in conventional farming.
Method of Application
Farmers apply green manure by blending available plant discards into the soil. Farmers begin the process of green manuring by growing legumes or collecting tree/shrub clippings. Harvesters gather the green manure crops and mix the plant material into the soil. The un-decomposed plants prepare the ground for cash crops by slowly releasing nutrients like nitrogen into the soil.
Farmers may decide to add the green manure into the soil before or after cash crop planting. This variety in planting schedules can be seen in rice farming.
Green manures are meant to be used alongside chemical fertilizers as a way to reduce our use of chemical fertilizers. When used alone, we cannot see all the advantages of green manures.
Functions
Green manures usually perform multiple functions that include soil improvement and soil protection:
Leguminous green manures such as clover and vetch contain nitrogen-fixing symbiotic bacteria in root nodules that fix atmospheric nitrogen in a form that plants can use. This performs the vital function of fertilization.
Depending on the species of cover crop grown, the amount of nitrogen released into the soil lies between 40 and 200 pounds per acre. With green manure use, the amount of nitrogen that is available to the succeeding crop is usually in the range of 40-60% of the total amount of nitrogen that is contained within the green manure crop.
{| class="wikitable"
|-
|+Average biomass and nitrogen yields of several legumes
! Crop
! Biomass (tons |
https://en.wikipedia.org/wiki/Factorial%20prime | A factorial prime is a prime number that is one less or one more than a factorial (all factorials greater than 1 are even).
The first 10 factorial primes (for n = 1, 2, 3, 4, 6, 7, 11, 12, 14) are :
2 (0! + 1 or 1! + 1), 3 (2! + 1), 5 (3! − 1), 7 (3! + 1), 23 (4! − 1), 719 (6! − 1), 5039 (7! − 1), 39916801 (11! + 1), 479001599 (12! − 1), 87178291199 (14! − 1), ...
n! − 1 is prime for :
n = 3, 4, 6, 7, 12, 14, 30, 32, 33, 38, 94, 166, 324, 379, 469, 546, 974, 1963, 3507, 3610, 6917, 21480, 34790, 94550, 103040, 147855, 208003, ... (resulting in 27 factorial primes)
n! + 1 is prime for :
n = 0, 1, 2, 3, 11, 27, 37, 41, 73, 77, 116, 154, 320, 340, 399, 427, 872, 1477, 6380, 26951, 110059, 150209, 288465, 308084, 422429, ... (resulting in 24 factorial primes - the prime 2 is repeated)
No other factorial primes are known .
When both n! + 1 and n! − 1 are composite, there must be at least 2n + 1 consecutive composite numbers around n!, since besides n! ± 1 and n! itself, also, each number of form n! ± k is divisible by k for 2 ≤ k ≤ n. However, the necessary length of this gap is asymptotically smaller than the average composite run for integers of similar size (see prime gap).
See also
Primorial prime
External links
The Top Twenty: Factorial primes from the Prime Pages
Factorial Prime Search from PrimeGrid
References
Integer sequences
Classes of prime numbers
Factorial and binomial topics |
https://en.wikipedia.org/wiki/Primorial%20prime | In mathematics, a primorial prime is a prime number of the form pn# ± 1, where pn# is the primorial of pn (i.e. the product of the first n primes).
Primality tests show that
pn# − 1 is prime for n = 2, 3, 5, 6, 13, 24, ...
pn# + 1 is prime for n = 0, 1, 2, 3, 4, 5, 11, ...
The first term of the second sequence is 0 because p0# = 1 is the empty product, and thus p0# + 1 = 2, which is prime. Similarly, the first term of the first sequence is not 1, because p1# = 2, and 2 − 1 = 1 is not prime.
The first few primorial primes are
2, 3, 5, 7, 29, 31, 211, 2309, 2311, 30029, 200560490131, 304250263527209, 23768741896345550770650537601358309
, the largest known primorial prime (of the form pn# − 1) is 3267113# − 1 (n = 234,725) with 1,418,398 digits, found by the PrimeGrid project.
, the largest known prime of the form pn# + 1 is 392113# + 1 (n = 33,237) with 169,966 digits, found in 2001 by Daniel Heuer.
Euclid's proof of the infinitude of the prime numbers is commonly misinterpreted as defining the primorial primes, in the following manner:
Assume that the first n consecutive primes including 2 are the only primes that exist. If either pn# + 1 or pn# − 1 is a primorial prime, it means that there are larger primes than the nth prime (if neither is a prime, that also proves the infinitude of primes, but less directly; each of these two numbers has a remainder of either p − 1 or 1 when divided by any of the first n primes, and hence all its prime factors are larger than pn).
See also
Compositorial
Euclid number
Factorial prime
References
See also
A. Borning, "Some Results for and " Math. Comput. 26 (1972): 567–570.
Chris Caldwell, The Top Twenty: Primorial at The Prime Pages.
Harvey Dubner, "Factorial and Primorial Primes." J. Rec. Math. 19 (1987): 197–203.
Paulo Ribenboim, The New Book of Prime Number Records. New York: Springer-Verlag (1989): 4.
Integer sequences
Classes of prime numbers |
https://en.wikipedia.org/wiki/Clipper%20chip | The Clipper chip was a chipset that was developed and promoted by the United States National Security Agency (NSA) as an encryption device that secured "voice and data messages" with a built-in backdoor that was intended to "allow Federal, State, and local law enforcement officials the ability to decode intercepted voice and data transmissions." It was intended to be adopted by telecommunications companies for voice transmission. Introduced in 1993, it was entirely defunct by 1996.
Key escrow
The Clipper chip used a data encryption algorithm called Skipjack to transmit information and the Diffie–Hellman key exchange-algorithm to distribute the public keys between peers. Skipjack was invented by the National Security Agency of the U.S. Government; this algorithm was initially classified SECRET, which prevented it from being subjected to peer review from the encryption research community. The government did state that it used an 80-bit key, that the algorithm was symmetric, and that it was similar to the DES algorithm. The Skipjack algorithm was declassified and published by the NSA on June 24, 1998. The initial cost of the chips was said to be $16 (unprogrammed) or $26 (programmed), with its logic designed by Mykotronx, and fabricated by VLSI Technology, Inc.
At the heart of the concept was key escrow. In the factory, any new telephone or other device with a Clipper chip would be given a cryptographic key, that would then be provided to the government in escrow. If government agencies "established their authority" to listen to a communication, then the key would be given to those government agencies, who could then decrypt all data transmitted by that particular telephone. The newly formed Electronic Frontier Foundation preferred the term "key surrender" to emphasize what they alleged was really occurring.
Clinton Administration
The Clinton Administration argued that the Clipper chip was essential for law enforcement to keep up with the constantly progressing te |
https://en.wikipedia.org/wiki/Arctometatarsal | An arctometatarsalian organism is one in which the proximal part of the middle metatarsal is pinched between the surrounding metatarsals. The trait appears to be highly homoplastic, common in certain sorts of dinosaurs accustomed to running (among them the tyrannosauroids, ornithomimosaurs, and troodontids), to evenly transmit force to the metatarsals.
References
Evolutionary biology concepts
Vertebrate anatomy
Skeletal system
Dinosaur anatomy |
https://en.wikipedia.org/wiki/Mac%20OS%20X%20Jaguar | Mac OS X Jaguar (version 10.2) is the third major release of macOS, Apple's desktop and server operating system. It superseded Mac OS X 10.1 and preceded Mac OS X Panther. The operating system was released on August 23, 2002 either for single-computer installations, and in a "family pack", which allowed five installations on separate computers in one household. Jaguar was the first Mac OS X release to publicly use its code name in marketing and advertisements.
System requirements
Mac OS X Jaguar required a PowerPC G3 or G4 CPU and 128 MB of RAM. Special builds were released for the first PowerPC G5 systems released by Apple.
New and changed features
Jaguar introduced many new features to Mac OS X, which are still supported to this day, including MPEG-4 support in QuickTime, Address Book, and Inkwell for handwriting recognition. It also included the first release of Apple's Zeroconf implementation, Rendezvous (later renamed to Bonjour), which allows devices on the same network to automatically discover each other and offer available services, such as file sharing, shared scanners, and printers, to the user.
Mac OS X Jaguar Server 10.2.2 added journaling to HFS Plus, the native Macintosh file system, to add increased reliability and data recovery features. This was later added to the standard Mac OS X in version 10.3 Panther.
Jaguar saw the debut of Quartz Extreme, a technology used to composite graphics directly on the video card, without the use of software to composite windows. The technology allotted the task of drawing the 3D surface of windows to the video card, rather than to the CPU, to increase interface responsiveness and performance.
Universal Access was added to allow the Macintosh to be usable by disabled computer users.
The user interface of Jaguar was also amended to add search features to the Finder using the updated Sherlock 3.
Internally, Jaguar also added the Common Unix Printing System (also known as CUPS), a modular printing system for U |
https://en.wikipedia.org/wiki/ANSEL | ANSEL, the American National Standard for Extended Latin Alphabet Coded Character Set for Bibliographic Use, was a character set used in text encoding. It provided a table of coded values for the representation of characters of the extended Latin alphabet in machine-readable form for thirty-five languages written in the Latin alphabet and for fifty-one romanized languages. ANSEL adds 63 graphic characters to ASCII, including 29 combining diacritic characters.
The initial revision of ANSEL was released in 1985, and before 1993 it was registered as Registration #231 in the ISO International Register of Coded Character Sets to be Used with Escape Sequences. The standard was reaffirmed in 2003 although it has been administratively withdrawn by ANSI effective 14 February 2013.
The requirement of hardware capable of overprinting accents doomed this from ever becoming a popular extended ASCII.
Code page layout
The following table shows ANSI/NISO Z39.47-1993 (R2003). Non-ASCII characters are shown with their Unicode code point. A combining diacritic precedes the spacing character on which it should be superimposed (in Unicode the combining diacritic is after the base character).
Use
GEDCOM
The GEDCOM specification for exchanging genealogical data refers to ANSEL (ANSI/NISO Z39.47-1985) as a valid text encoding for GEDCOM files and extends it with additional characters which are shown in the following table.
MARC21
The Extended Latin character set from MARC 21 is synchronized with ANSEL but additionally supports the eszett (ß) character at C7 and the euro sign (€) at C8.
References
External links
National Information Standards Organization (NISO)
American National Standards Institute (ANSI)
ANSI/NISO Z39.47-1985
ANSI/NISO Z39.47-1993 (R2003)
ISO-IR 231
MARC 21 Code Table Extended Latin (ANSEL)
American Library Association
Character sets |
https://en.wikipedia.org/wiki/Sanitary%20sewer | A sanitary sewer is an underground pipe or tunnel system for transporting sewage from houses and commercial buildings (but not stormwater) to a sewage treatment plant or disposal. Sanitary sewers are a type of gravity sewer and are part of an overall system called a "sewage system" or sewerage. Sanitary sewers serving industrial areas may also carry industrial wastewater. In municipalities served by sanitary sewers, separate storm drains may convey surface runoff directly to surface waters. An advantage of sanitary sewer systems is that they avoid combined sewer overflows. Sanitary sewers are typically much smaller in diameter than combined sewers which also transport urban runoff. Backups of raw sewage can occur if excessive stormwater inflow or groundwater infiltration occurs due to leaking joints, defective pipes etc. in aging infrastructure.
Purpose
Sewage treatment is less effective when sanitary waste is diluted with stormwater, and combined sewer overflows occur when runoff from heavy rainfall or snowmelt exceeds the hydraulic capacity of sewage treatment plants. To overcome these disadvantages, some cities built separate sanitary sewers to collect only municipal wastewater and exclude stormwater runoff, which is collected in separate storm drains. The decision to build a combined sewer system or two separate systems is mainly based on the need for sewage treatment and the cost of providing treatment during heavy rain events. Many cities with combined sewer systems built their systems prior to installing sewage treatment plants, and have not subsequently replaced those sewer systems.
Types
Conventional gravity sewers
In the developed world, sewers are pipes from buildings to one or more levels of larger underground trunk mains, which transport the sewage to sewage treatment facilities. Vertical pipes, usually made of precast concrete, called manholes, connect the mains to the surface. Depending upon site application and use, these vertical pipes can be |
https://en.wikipedia.org/wiki/120%20%28number%29 | 120 (one hundred [and] twenty) is the natural number following 119 and preceding 121.
In the Germanic languages, the number 120 was also formerly known as "one hundred". This "hundred" of six score is now obsolete, but is described as the long hundred or great hundred in historical contexts.
In mathematics
120 is
the factorial of 5, i.e., .
the fifteenth triangular number, as well as the sum of the first eight triangular numbers, making it also a tetrahedral number. 120 is the smallest number to appear six times in Pascal's triangle (as all triangular and tetragonal numbers appear in it). Because 15 is also triangular, 120 is a doubly triangular number. 120 is divisible by the first 5 triangular numbers and the first 4 tetrahedral numbers. It is the eighth hexagonal number.
highly composite, superior highly composite, superabundant, and colossally abundant number, with its 16 divisors, it is the smallest number to have that many divisors. It is also a sparsely totient number. 120 is also the smallest highly composite number as well as the first multiple of six with no adjacent prime number, being adjacent to and .
120 is the first multiply perfect number of order three (a 3-perfect or triperfect number). The sum of its factors (including one and itself) sum to 360; exactly three times 120. Note that perfect numbers are order two (2-perfect) by the same definition.
120 is the sum of a twin prime pair (59 + 61) and the sum of four consecutive prime numbers (23 + 29 + 31 + 37), four consecutive powers of two (8 + 16 + 32 + 64), and four consecutive powers of three (3 + 9 + 27 + 81).
120 is divisible by the number of primes below it, 30 in this case. However, there is no integer which has 120 as the sum of its proper divisors, making 120 an untouchable number.
The sum of Euler's totient function over the first nineteen integers is 120.
As 120 is a factorial and one less than a square (), it, with 11, is one of the few Brown number pairs.
120 appears in P |
https://en.wikipedia.org/wiki/119%20%28number%29 | 119 (one hundred [and] nineteen) is the natural number following 118 and preceding 120.
Mathematics
119 is a Perrin number, preceded in the sequence by 51, 68, 90 (it is the sum of the first two mentioned).
119 is the sum of five consecutive primes (17 + 19 + 23 + 29 + 31).
119 is the sum of seven consecutive primes (7 + 11 + 13 + 17 + 19 + 23 + 29).
119 is a highly cototient number.
119 is the order of the largest cyclic subgroups of the monster group.
119 is the smallest composite number that is 1 less than a factorial (120 is 5!).
119 is a semiprime, and the third in the {7×q} family.
Telephony
119 is an emergency telephone number in some countries
A number to report youth at risk in France
119 is the emergency number in Afghanistan that belongs to police and interior ministry.
The South Korean emergency call number
The Chinese fire station call number
119 is the number for the UK's NHS Test and Trace service (created in response to the COVID-19 pandemic)
In other fields
119 is the default port for unencrypted NNTP connections.
Project 119 is a governmental program of the People's Republic of China targeting sports that China has not traditionally excelled in at the Summer Olympics, to maximize the number of medals won during the games.
119 is also the atomic number of the theoretical element ununennium.
Union Pacific No. 119, a 4-4-0 American Type standard gauge steam locomotive of the Union Pacific Railroad that was memorialized in railroading history on the right-hand side of Andrew J. Russell's famous "Joining of the Lines" photograph taken on 10 May 1869, at Promontory, Utah, during the celebration of the completion of the First transcontinental railroad, where it was cowcatcher to cowcatcher with Central Pacific Railroad's Jupiter (locomotive).
See also
List of highways numbered 119
References
Integers |
https://en.wikipedia.org/wiki/Mackie%201604-VLZ%20Pro | The 1604-VLZ Pro is a compact analog mixer manufactured by professional audio equipment brand Mackie. It features sixteen input channels, four output sub-groups, and a user-replaceable fuse. Each of the input channels features a high-quality microphone preamplifier.
VLZ stands for Very Low Impedance.
References
LOUD Technologies Inc. (n.d.a). Mackie 1604-VLZ Pro. Retrieved December 21, 2003 from http://www.mackie.com/products/1604vlzpro/
LOUD Technologies Inc. (n.d.b). Mackie Mixers. Retrieved December 21, 2003 from http://www.mackie.com/products/mixers/index.html
Mixing consoles
LOUD Audio |
https://en.wikipedia.org/wiki/Leibniz%27s%20notation | In calculus, Leibniz's notation, named in honor of the 17th-century German philosopher and mathematician Gottfried Wilhelm Leibniz, uses the symbols and to represent infinitely small (or infinitesimal) increments of and , respectively, just as and represent finite increments of and , respectively.
Consider as a function of a variable , or = . If this is the case, then the derivative of with respect to , which later came to be viewed as the limit
was, according to Leibniz, the quotient of an infinitesimal increment of by an infinitesimal increment of , or
where the right hand side is Joseph-Louis Lagrange's notation for the derivative of at . The infinitesimal increments are called . Related to this is the integral in which the infinitesimal increments are summed (e.g. to compute lengths, areas and volumes as sums of tiny pieces), for which Leibniz also supplied a closely related notation involving the same differentials, a notation whose efficiency proved decisive in the development of continental European mathematics.
Leibniz's concept of infinitesimals, long considered to be too imprecise to be used as a foundation of calculus, was eventually replaced by rigorous concepts developed by Weierstrass and others in the 19th century. Consequently, Leibniz's quotient notation was re-interpreted to stand for the limit of the modern definition. However, in many instances, the symbol did seem to act as an actual quotient would and its usefulness kept it popular even in the face of several competing notations. Several different formalisms were developed in the 20th century that can give rigorous meaning to notions of infinitesimals and infinitesimal displacements, including nonstandard analysis, tangent space, O notation and others.
The derivatives and integrals of calculus can be packaged into the modern theory of differential forms, in which the derivative is genuinely a ratio of two differentials, and the integral likewise behaves in exact accordance w |
https://en.wikipedia.org/wiki/List%20of%20fire-retardant%20materials | Fire-retardant materials are designed to burn slowly.
Fire-retardant materials should not be confused with fire-resistant materials. A fire resistant material is one which is designed to resist burning and withstand heat. An example of a fire-resistant material is one which is used in bunker gear worn by firefighters to protect them from the flames of a burning building.
In the United Kingdom, after two significant construction fires which resulted in a combined loss of £1,500 million, The Joint Code of Practice was introduced by the Fire Protection Association (FPA), the UK's national fire safety organisation, to prevent fires on buildings undergoing construction work. The Joint Code of Practice provides advice on how to prevent fires such as through the use of flame-retardant temporary protection materials: for example, some high quality floor protectors are designed to burn slowly and prevent the spread of fires.
Fire-retardant materials used in buildings
Iron
Mineral wool
Gypsum boards
Asbestos cement
Perlite boards
Corriboard
Calcium silicate
Sodium silicate
Potassium silicate
Treated lumber plywood
Treated vegetable fiber (e.g., cotton, jute, kenaf, hemp, flax, etc..)
Fire-retardant treated wood
Brick
Concrete
Cement render
Intumescent paint
Glass
Magnesium oxide (MgO)
Geobond asbestos substitute
Fire textiles
PBI
Aramid - para and meta
Flame retardant cotton
Coated nylon
Carbon foam (CFOAM)
Melamine
Modacrylic
Phasing-out
Many common brominated flame retardants are being phased-out by manufacturers.
See also
Fireproof
Non-flammable
References
External links
European Flame Retardants Association EFRA brings together and represents the leading organisations which manufacture, market or use flame retardants in Europe.
Engineering-related lists
Flame retardants
Materials science |
https://en.wikipedia.org/wiki/Geometric%20standard%20deviation | In probability theory and statistics, the geometric standard deviation (GSD) describes how spread out are a set of numbers whose preferred average is the geometric mean. For such data, it may be preferred to the more usual standard deviation. Note that unlike the usual arithmetic standard deviation, the geometric standard deviation is a multiplicative factor, and thus is dimensionless, rather than having the same dimension as the input values. Thus, the geometric standard deviation may be more appropriately called geometric SD factor. When using geometric SD factor in conjunction with geometric mean, it should be described as "the range from (the geometric mean divided by the geometric SD factor) to (the geometric mean multiplied by the geometric SD factor), and one cannot add/subtract "geometric SD factor" to/from geometric mean.
Definition
If the geometric mean of a set of numbers is denoted as then the geometric standard deviation is
Derivation
If the geometric mean is
then taking the natural logarithm of both sides results in
The logarithm of a product is a sum of logarithms (assuming is positive for all so
It can now be seen that is the arithmetic mean of the set therefore the arithmetic standard deviation of this same set should be
This simplifies to
Geometric standard score
The geometric version of the standard score is
If the geometric mean, standard deviation, and z-score of a datum are known, then the raw score can be reconstructed by
Relationship to log-normal distribution
The geometric standard deviation is used as a measure of log-normal dispersion analogously to the geometric mean. As the log-transform of a log-normal distribution results in a normal distribution, we see that the
geometric standard deviation is the exponentiated value of the standard deviation of the log-transformed values, i.e.
As such, the geometric mean and the geometric standard deviation of a sample of
data from a log-normally distributed population may be us |
https://en.wikipedia.org/wiki/Winny | Winny (also known as WinNY) is a Japanese peer-to-peer (P2P) file-sharing program developed by Isamu Kaneko, a research assistant at the University of Tokyo in 2002. Like Freenet, a user must add an encrypted node list in order to connect to other nodes on the network. Users choose three cluster words which symbolize their interests, and then Winny connects to other nodes which share these cluster words, downloading and storing encrypted data from cache of these neighbors in a distributed data store. If users want a particular file, they set up triggers (keywords), and Winny will download files marked by these triggers. The encryption was meant to provide anonymity, but Winny also included bulletin boards where users would announce uploads, and the IP address of posters could be discovered through these boards. While Freenet was implemented in Java, Winny was implemented as a Windows C++ application.
The software takes its name from WinMX, where the M and the X are each advanced one letter in the Latin alphabet, to N and Y. Netagent published a survey in June 2018 suggesting that Winny was still the most popular p2p network in Japan ahead of Perfect Dark (P2P) and Share (P2P) with approximately 45,000 nodes connecting each day over Golden Week. The number of nodes on Winny appears to be holding steady compared with 2015.
Kaneko first announced Winny on the Download Software board of the 2channel (2ch for short) Japanese bulletin board site. Since 2channel users often refer to anonymous users by their post numbers, Kaneko came to be known as "Mr. 47" ("47-Shi", or 47氏 in Japanese), or just "47".
After Winny's development stopped, a new peer-to-peer application, Share, was developed to be a successor.
Antinny
Since August 2003, several worms called "Antinny" have spread on the Winny network.
Some versions of Antinny work as follows:
Upload files from the host computer onto the Winny network.
Upload screenshots onto an image board.
Denial-of-service atta |
https://en.wikipedia.org/wiki/Brine%20shrimp | Artemia is a genus of aquatic crustaceans also known as brine shrimp. It is the only genus in the family Artemiidae. The first historical record of the existence of Artemia dates back to the first half of the 10th century AD from Lake Urmia, Iran, with an example called by an Iranian geographer an "aquatic dog", although the first unambiguous record is the report and drawings made by Schlösser in 1757 of animals from Lymington, England. Artemia populations are found worldwide, typically in inland saltwater lakes, but occasionally in oceans. Artemia are able to avoid cohabiting with most types of predators, such as fish, by their ability to live in waters of very high salinity (up to 25%).
The ability of the Artemia to produce dormant eggs, known as cysts, has led to extensive use of Artemia in aquaculture. The cysts may be stored indefinitely and hatched on demand to provide a convenient form of live feed for larval fish and crustaceans. Nauplii of the brine shrimp Artemia constitute the most widely used food item, and over of dry Artemia cysts are marketed worldwide annually. In addition, the resilience of Artemia makes them ideal animals running biological toxicity assays and it has become a model organism used to test the toxicity of chemicals. Breeds of Artemia are sold as novelty gifts under the marketing name Sea-Monkeys.
Description
The brine shrimp Artemia comprises a group of seven to nine species very likely to have diverged from an ancestral form living in the Mediterranean area about , around the time of the Messinian salinity crisis.
The Laboratory of Aquaculture & Artemia Reference Center at Ghent University possesses the largest known Artemia cyst collection, a cyst bank containing over 1,700 Artemia population samples collected from different locations around the world.
Artemia is a typical primitive arthropod with a segmented body to which is attached broad leaf-like appendages. The body usually consists of 19 segments, the first 11 of which ha |
https://en.wikipedia.org/wiki/Rebasing | In computing, rebasing is the process of modifying data based on one reference to another. It can be one of the following:
Shared libraries
Rebasing is the process of creating a shared library image in such a way that it is guaranteed to use virtual memory without conflicting with any other shared libraries loadable in the system.
IBM VM/370 discontinuous saved segments (DCSS) were an early example of this technique, though not called rebasing. The technique is used extensively on Win32 platforms to avoid the overhead of address relocation of system DLLs by the loader.
Some security extensions to Linux/x86 use rebasing to force the use of code addresses below 0x00ffffff in order to introduce a 0x00 byte into all code pointers; This eliminates a certain class of buffer overflow security problems related to improper checking of null-terminated strings, common in the C programming language.
Other uses
Rebasing is the act of moving changesets to a different branch when using a revision control system or in some systems, by synchronizing a branch with the originating branch by merging all new changes in the latter to the former. For example, Git and Darcs do this (but Darcs extends the concept and calls it "patch commutation").
The mechanism that the Microsoft Exchange or Outlook daylight saving time (DST) rebasing tool TZMOVE.EXE uses to recalculate and reschedule appointment dates that are affected by DST.
See also
Relocation (computing)
Position-independent code
Portable Executable (PE)
High memory area (HMA)
Dynamic dead code elimination
Further reading
Code: Errata:
Computer libraries |
https://en.wikipedia.org/wiki/Cymatics | Cymatics (from ) is a subset of modal vibrational phenomena. The term was coined by Swiss physician Hans Jenny (1904–1972). Typically the surface of a plate, diaphragm, or membrane is vibrated, and regions of maximum and minimum displacement are made visible in a thin coating of particles, paste, or liquid. Different patterns emerge in the excitatory medium depending on the geometry of the plate and the driving frequency.
The apparatus employed can be simple, such as the Chinese spouting bowl, in which copper handles are rubbed and cause the copper bottom elements to vibrate. Other examples include the Chladni Plate and the so-called cymascope.
History
On July 8, 1680, Robert Hooke was able to see the nodal patterns associated with the modes of vibration of glass plates. Hooke ran a bow (musical) along the edge of a glass plate covered with flour, and saw the nodal patterns emerge.
The German musician and physicist Ernst Chladni noticed in the eighteenth century that the modes of vibration of a membrane or a plate can be observed by sprinkling the vibrating surface with a fine dust (e.g., lycopodium powder, flour or fine sand). The powder moves due to the vibration and accumulates progressively in points of the surface corresponding to the sound vibration. The points form a pattern of lines, known as "nodal lines of the vibration mode". The normal modes of vibration, and the pattern of nodal lines associated with each of these, are completely determined, for a surface with homogeneous mechanical characteristics, from the geometric shape of the surface and by the way in which the surface is constrained.
Experiments of this kind, similar to those carried out earlier by Galileo Galilei around 1630 and by Robert Hooke in 1680, were later perfected by Chladni, who introduced them systematically in 1787 in his book Entdeckungen über die Theorie des Klanges (Discoveries on the theory of sound). This provided an important contribution to the understanding of acoustic ph |
https://en.wikipedia.org/wiki/Staining | Staining is a technique used to enhance contrast in samples, generally at the microscopic level. Stains and dyes are frequently used in histology (microscopic study of biological tissues), in cytology (microscopic study of cells), and in the medical fields of histopathology, hematology, and cytopathology that focus on the study and diagnoses of diseases at the microscopic level. Stains may be used to define biological tissues (highlighting, for example, muscle fibers or connective tissue), cell populations (classifying different blood cells), or organelles within individual cells.
In biochemistry, it involves adding a class-specific (DNA, proteins, lipids, carbohydrates) dye to a substrate to qualify or quantify the presence of a specific compound. Staining and fluorescent tagging can serve similar purposes. Biological staining is also used to mark cells in flow cytometry, and to flag proteins or nucleic acids in gel electrophoresis. Light microscopes are used for viewing stained samples at high magnification, typically using bright-field or epi-fluorescence illumination.
Staining is not limited to only biological materials, since it can also be used to study the structure of other materials; for example, the lamellar structures of semi-crystalline polymers or the domain structures of block copolymers.
In vivo vs In vitro
In vivo staining (also called vital staining or intravital staining) is the process of dyeing living tissues. By causing certain cells or structures to take on contrasting colours, their form (morphology) or position within a cell or tissue can be readily seen and studied. The usual purpose is to reveal cytological details that might otherwise not be apparent; however, staining can also reveal where certain chemicals or specific chemical reactions are taking place within cells or tissues.
In vitro staining involves colouring cells or structures that have been removed from their biological context. Certain stains are often combined to reveal mo |
https://en.wikipedia.org/wiki/Distribution%20frame | In telecommunications, a distribution frame is a passive device which terminates cables, allowing arbitrary interconnections to be made.
For example, the Main Distribution Frame (MDF) located at a telephone central office terminates the cables leading to subscribers on the one hand, and cables leading to active equipment (such as DSLAMs and telephone switches) on the other. Service is provided to a subscriber by manually wiring a twisted pair (called a jumper wire) between the telephone line and the relevant DSL or POTS line circuit.
In broadcast engineering, a distribution frame is a location within an apparatus room through which all signals (audio, video, or data) pass, with the ability to arbitrarily route and connect sources and destinations between studios and other internal and external points. Connections can either be soldered, or made using terminal blocks. Because the frame may carry live broadcast signals, it may be considered part of the airchain.
In data communication, a building distribution frame (BDF) houses data switches, etc.
Types
Distribution frames for specific types of signals often have specific initialisms:
DDF—digital distribution frame
IDF—Intermediate distribution frame
MDF—Main distribution frame
ODF or OFDF—optical fiber distribution frame
VDF—voice distribution frame
Modernization
Distribution frames may grow to extremely large sizes. In major installations, audio distribution frames can have as many as 10,000 incoming and outgoing separate copper wires (balanced audio signals require two wires plus earth ground for each signal). Telephone signals do not use a separate earth ground wire, but some urban exchanges have about 250,000 wires on their MDF. Installing and rewiring these jumpers is a labour-intensive task, leading to attempts in the industry to devise so-called active distribution frames or Automated Main Distribution Frames. The principal issues which stand in the way of their widespread adoption are cost and relia |
https://en.wikipedia.org/wiki/Human%20biology | Human biology is an interdisciplinary area of academic study that examines humans through the influences and interplay of many diverse fields such as genetics, evolution, physiology, anatomy, epidemiology, anthropology, ecology, nutrition, population genetics, and sociocultural influences. It is closely related to the biomedical sciences, biological anthropology and other biological fields tying in various aspects of human functionality. It wasn't until the 20th century when biogerontologist, Raymond Pearl, founder of the journal Human Biology, phrased the term "human biology" in a way to describe a separate subsection apart from biology.
It is also a portmanteau term that describes all biological aspects of the human body, typically using the human body as a type organism for Mammalia, and in that context it is the basis for many undergraduate University degrees and modules.
Most aspects of human biology are identical or very similar to general mammalian biology. In particular, and as examples, humans :
maintain their body temperature
have an internal skeleton
have a circulatory system
have a nervous system to provide sensory information and operate and coordinate muscular activity.
have a reproductive system in which they bear live young and produce milk.
have an endocrine system and produce and eliminate hormones and other bio-chemical signalling agents
have a respiratory system where air is inhaled into lungs and oxygen is used to produce energy.
have an immune system to protect against disease
Excrete waste as urine and feces.
History
The start of integrated human biology started in the 1920's, caused by Charles Darwin's theories, such as evolution, were re-conceptualized by many scientists. Human attributes, such as child growth and genetics, were put into question and thus human biology was created.
Typical human attributes
The key aspects of human biology are those ways in which humans are substantially different from other mammals.
Humans ha |
https://en.wikipedia.org/wiki/Random%20Fibonacci%20sequence | In mathematics, the random Fibonacci sequence is a stochastic analogue of the Fibonacci sequence defined by the recurrence relation , where the signs + or − are chosen at random with equal probability , independently for different . By a theorem of Harry Kesten and Hillel Furstenberg, random recurrent sequences of this kind grow at a certain exponential rate, but it is difficult to compute the rate explicitly. In 1999, Divakar Viswanath showed that the growth rate of the random Fibonacci sequence is equal to 1.1319882487943... , a mathematical constant that was later named Viswanath's constant.
Description
A random Fibonacci sequence is an integer random sequence given by the numbers for natural numbers , where and the subsequent terms are chosen randomly according to the random recurrence relation
An instance of the random Fibonacci sequence starts with 1,1 and the value of the each subsequent term is determined by a fair coin toss: given two consecutive elements of the sequence, the next element is either their sum or their difference with probability 1/2, independently of all the choices made previously. If in the random Fibonacci sequence the plus sign is chosen at each step, the corresponding instance is the Fibonacci sequence (Fn),
If the signs alternate in minus-plus-plus-minus-plus-plus-... pattern, the result is the sequence
However, such patterns occur with vanishing probability in a random experiment. In a typical run, the terms will not follow a predictable pattern:
Similarly to the deterministic case, the random Fibonacci sequence may be profitably described via matrices:
where the signs are chosen independently for different n with equal probabilities for + or −. Thus
where (Mk) is a sequence of independent identically distributed random matrices taking values A or B with probability 1/2:
Growth rate
Johannes Kepler discovered that as n increases, the ratio of the successive terms of the Fibonacci sequence (Fn) approaches the golden ratio wh |
https://en.wikipedia.org/wiki/Abelian%20and%20Tauberian%20theorems | In mathematics, Abelian and Tauberian theorems are theorems giving conditions for two methods of summing divergent series to give the same result, named after Niels Henrik Abel and Alfred Tauber. The original examples are Abel's theorem showing that if a series converges to some limit then its Abel sum is the same limit, and Tauber's theorem showing that if the Abel sum of a series exists and the coefficients are sufficiently small (o(1/n)) then the series converges to the Abel sum. More general Abelian and Tauberian theorems give similar results for more general summation methods.
There is not yet a clear distinction between Abelian and Tauberian theorems, and no generally accepted definition of what these terms mean. Often, a theorem is called "Abelian" if it shows that some summation method gives the usual sum for convergent series, and is called "Tauberian" if it gives conditions for a series summable by some method that allows it to be summable in the usual sense.
In the theory of integral transforms, Abelian theorems give the asymptotic behaviour of the transform based on properties of the original function. Conversely, Tauberian theorems give the asymptotic behaviour of the original function based on properties of the transform but usually require some restrictions on the original function.
Abelian theorems
For any summation method L, its Abelian theorem is the result that if c = (cn) is a convergent sequence, with limit C, then L(c) = C.
An example is given by the Cesàro method, in which L is defined as the limit of the arithmetic means of the first N terms of c, as N tends to infinity. One can prove that if c does converge to C, then so does the sequence (dN) where
To see that, subtract C everywhere to reduce to the case C = 0. Then divide the sequence into an initial segment, and a tail of small terms: given any ε > 0 we can take N large enough to make the initial segment of terms up to cN average to at most ε/2, while each term in the tail is bo |
https://en.wikipedia.org/wiki/Symmetry%20of%20second%20derivatives | In mathematics, the symmetry of second derivatives (also called the equality of mixed partials) refers to the possibility of interchanging the order of taking partial derivatives of a function
of variables without changing the result under certain conditions (see below). The symmetry is the assertion that the second-order partial derivatives satisfy the identity
so that they form an symmetric matrix, known as the function's Hessian matrix. Sufficient conditions for the above symmetry to hold are established by a result known as Schwarz's theorem, Clairaut's theorem, or Young's theorem.
In the context of partial differential equations it is called the Schwarz integrability condition.
Formal expressions of symmetry
In symbols, the symmetry may be expressed as:
Another notation is:
In terms of composition of the differential operator which takes the partial derivative with respect to :
.
From this relation it follows that the ring of differential operators with constant coefficients, generated by the , is commutative; but this is only true as operators over a domain of sufficiently differentiable functions. It is easy to check the symmetry as applied to monomials, so that one can take polynomials in the as a domain. In fact smooth functions are another valid domain.
History
The result on the equality of mixed partial derivatives under certain conditions has a long history. The list of unsuccessful proposed proofs started with Euler's, published in 1740, although already in 1721 Bernoulli had implicitly assumed the result with no formal justification. Clairaut also published a proposed proof in 1740, with no other attempts until the end of the 18th century. Starting then, for a period of 70 years, a number of incomplete proofs were proposed. The proof of Lagrange (1797) was improved by Cauchy (1823), but assumed the existence and continuity of the partial derivatives and . Other attempts were made by P. Blanchet (1841), Duhamel (1856), Sturm (1857), Schl |
https://en.wikipedia.org/wiki/Hessian%20matrix | In mathematics, the Hessian matrix, Hessian or (less commonly) Hesse matrix is a square matrix of second-order partial derivatives of a scalar-valued function, or scalar field. It describes the local curvature of a function of many variables. The Hessian matrix was developed in the 19th century by the German mathematician Ludwig Otto Hesse and later named after him. Hesse originally used the term "functional determinants". The Hessian is sometimes denoted by H or, ambiguously, by ∇2.
Definitions and properties
Suppose is a function taking as input a vector and outputting a scalar If all second-order partial derivatives of exist, then the Hessian matrix of is a square matrix, usually defined and arranged as
That is, the entry of the th row and the th column is
If furthermore the second partial derivatives are all continuous, the Hessian matrix is a symmetric matrix by the symmetry of second derivatives.
The determinant of the Hessian matrix is called the .
The Hessian matrix of a function is the transpose of the Jacobian matrix of the gradient of the function ; that is:
Applications
Inflection points
If is a homogeneous polynomial in three variables, the equation is the implicit equation of a plane projective curve. The inflection points of the curve are exactly the non-singular points where the Hessian determinant is zero. It follows by Bézout's theorem that a cubic plane curve has at most inflection points, since the Hessian determinant is a polynomial of degree
Second-derivative test
The Hessian matrix of a convex function is positive semi-definite. Refining this property allows us to test whether a critical point is a local maximum, local minimum, or a saddle point, as follows:
If the Hessian is positive-definite at then attains an isolated local minimum at If the Hessian is negative-definite at then attains an isolated local maximum at If the Hessian has both positive and negative eigenvalues, then is a saddle point for Otherw |
https://en.wikipedia.org/wiki/Minsk%20family%20of%20computers | Minsk family of mainframe computers was developed and produced in the Byelorussian SSR from 1959 to 1975.
Models
The MINSK-1 was a vacuum-tube digital computer that went into production in 1960.
The MINSK-2 was a solid-state digital computer that went into production in 1962.
The MINSK-22 was a modified version of Minsk-2 that went into production in 1965.
The MINSK-23 went into production in 1966.
The most advanced model was Minsk-32, developed in 1968. It supported COBOL, FORTRAN and ALGAMS (a version of ALGOL). This and earlier versions also used a machine-oriented language called AKI (AvtoKod "Inzhener", i.e., "Engineer's Autocode"). It stood somewhere between the native assembly language SSK (Sistema Simvolicheskogo Kodirovaniya, or "System of symbolic coding") and higher-level languages, like FORTRAN.
The word size was 31 bits for Minsk-1 and 37 bits for the other models.
At one point the Minsk-222 (an upgraded prototype based on the most popular model, Minsk-22) and Minsk-32 were considered as a potential base for a future unified line of mutually compatible mainframes — that would later become the ES EVM line, but despite being popular among users, good match between their tech and Soviet tech base and familiarity to both programmers and technicians lost to the proposal to copy the IBM/360 line of mainframes — the possibility to just copy all the software existing for it was deemed more important.
See also
Mark Nemenman
References
Further reading
(NB. Has info on the Minsk-32 character set.)
External links
Russian Virtual Computer Museum
Belarusian inventions
Soviet inventions
Mainframe computers
Science and technology in Belarus
Ministry of Radio Industry (USSR) computers |
https://en.wikipedia.org/wiki/Information%20and%20Content%20Exchange | Information and Content Exchange (ICE) is an XML-based protocol used for content syndication via the Internet. By using XML both sender and receiver have an agreed-upon language in which to communicate. Using a client–server architecture, ICE defines a syndicate/subscribe model that is comparable to the binary publish/subscribe protocol standards used in CORBA and DCOM. However, in ICE messages are delivered through XML, typically over an HTTP connection, rather than through a lower-level binary protocol.
History
The first standard specifically for web syndication, ICE was proposed by Firefly Networks and Vignette in January 1998. The two companies ceded control over the specification to the ICE consortium, which consisted of an authoring group and an advisory council. The ICE Authoring Group included Microsoft, Adobe, Sun, CNET, National Semiconductor, Tribune Media Services, Ziff Davis and Reuters, amongst others, and was limited to thirteen companies. The ICE advisory council included nearly a hundred members.
ICE was submitted to the World Wide Web Consortium standards body on October 26, 1998, and showcased in a press event the day after. The standard failed to benefit from the open-source implementation that W3C XML specifications often received.
Version 1.1 of the protocol was published on July 1, 2000. Version 2.0 featured improved web service support and was released on August 1, 2004. No further versions have appeared since.
Vignette had a demo version of an ICE-capable server named Site-to-Site in February 1998, aiming to show how the protocol could facilitate content exchange between websites. Site-to-site was initially scheduled for release in summer 1998; it was launched under the name Vignette Syndication Server on February 22, 1999. Through Syndication Server, Vignette became the primary ICE vendor.
In June 1999, Vignette invested $14 million in the leading web syndicator iSyndicate to adopt Vignette StoryServer for further development of the |
https://en.wikipedia.org/wiki/Challenge%E2%80%93response%20authentication | In computer security, challenge–response authentication is a family of protocols in which one party presents a question ("challenge") and another party must provide a valid answer ("response") to be authenticated.
The simplest example of a challenge–response protocol is password authentication, where the challenge is asking for the password and the valid response is the correct password.
An adversary who can eavesdrop on a password authentication can then authenticate itself by reusing the intercepted password. One solution is to issue multiple passwords, each of them marked with an identifier. The verifier can then present an identifier, and the prover must respond with the correct password for that identifier. Assuming that the passwords are chosen independently, an adversary who intercepts one challenge–response message pair has no clues to help with a different challenge at a different time.
For example, when other communications security methods are unavailable, the U.S. military uses the AKAC-1553 TRIAD numeral cipher to authenticate and encrypt some communications. TRIAD includes a list of three-letter challenge codes, which the verifier is supposed to choose randomly from, and random three-letter responses to them. For added security, each set of codes is only valid for a particular time period which is ordinarily 24 hours.
A more interesting challenge–response technique works as follows. Say Bob is controlling access to some resource. Alice comes along seeking entry. Bob issues a challenge, perhaps "52w72y". Alice must respond with the one string of characters which "fits" the challenge Bob issued. The "fit" is determined by an algorithm agreed upon by Bob and Alice. (The correct response might be as simple as "63x83z", with the algorithm changing each character of the challenge using a Caesar cipher. In the real world, the algorithm would be much more complex.) Bob issues a different challenge each time, and thus knowing a previous correct response ( |
https://en.wikipedia.org/wiki/Monotypic%20taxon | In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispecific" or "monospecific" is sometimes preferred. In botanical nomenclature, a monotypic genus is a genus in the special case where a genus and a single species are simultaneously described. In contrast, an oligotypic taxon contains more than one but only a very few subordinate taxa.
Examples
Just as the term monotypic is used to describe a taxon including only one subdivision, the contained taxon can also be referred to as monotypic within the higher-level taxon, e.g. a genus monotypic within a family. Some examples of monotypic groups are:
Plants
In the order Amborellales, there is only one family, Amborellaceae and there is only one genus, Amborella, and in this genus there is only one species, namely Amborella trichopoda.
The flowering plant Breonadia salicina is the only species in the monotypic genus Breonadia.
The family Cephalotaceae includes only one genus, Cephalotus, and only one species, Cephalotus follicularis – the Albany pitcher plant.
The division Ginkgophyta is monotypic, containing the single class Ginkgoopsida. This class is also monotypic, containing the single order Ginkgoales.
Flowering plant Nandina domestica is the only species in the genus Nandina.
It is today generally accepted that cannabis (Cannabis sativa) is a monospecific genus.
Animals
The madrone butterfly is the only species in the monotypic genus Eucheira. However, there are two subspecies of this butterfly, E. socialis socialis and E. socialis westwoodi, which means the species E. socialis is not monotypic.
Erithacus rubecula, the European robin, is the only extant member of its genus.
Delphinapterus leucas or the beluga whale is the only member of its genus and lacks subspecies.
Dugong dugong is the only species in the monotypic gen |
https://en.wikipedia.org/wiki/Inkscape | Inkscape is a free and open-source vector graphics editor for GNU/Linux, Windows and macOS. It offers a rich set of features and is widely used for both artistic and technical illustrations such as cartoons, clip art, logos, typography, diagramming and flowcharting. It uses vector graphics to allow for sharp printouts and renderings at unlimited resolution and is not bound to a fixed number of pixels like raster graphics. Inkscape uses the standardized Scalable Vector Graphics (SVG) file format as its main format, which is supported by many other applications including web browsers. It can import and export various other file formats, including SVG, AI, EPS, PDF, PS and PNG.
Inkscape can render primitive vector shapes (e.g. rectangles, ellipses, polygons, arcs, spirals, stars and 3D boxes) and text. These objects may be filled with solid colors, patterns, radial or linear color gradients and their borders may be stroked, both with adjustable transparency. Embedding and optional tracing of raster graphics is also supported, enabling the editor to create vector graphics from photos and other raster sources. Created shapes can be further manipulated with transformations, such as moving, rotating, scaling and skewing.
History
Inkscape began in 2003 as a code fork of the Sodipodi project. Sodipodi, developed since 1999, was itself based on Raph Levien's Gill (GNOME Illustration Application). One of the main priorities of the Inkscape project was interface consistency and usability by following the GNOME human interface guidelines.
Inkscape FAQ interprets the word Inkscape as a compound of ink and .
Four former Sodipodi developers (Ted Gould, Bryce Harrington, Nathan Hursten, and MenTaLguY) led the fork, citing differences over project objectives, openness to third-party contributions, and technical disagreements. They said that Inkscape would focus development on implementing the complete SVG standard, whereas Sodipodi development emphasized developing a general-purp |
https://en.wikipedia.org/wiki/Teichoic%20acid | Teichoic acids (cf. Greek τεῖχος, teīkhos, "wall", to be specific a fortification wall, as opposed to τοῖχος, toīkhos, a regular wall) are bacterial copolymers of glycerol phosphate or ribitol phosphate and carbohydrates linked via phosphodiester bonds.
Teichoic acids are found within the cell wall of most Gram-positive bacteria such as species in the genera Staphylococcus, Streptococcus, Bacillus, Clostridium, Corynebacterium, and Listeria, and appear to extend to the surface of the peptidoglycan layer. They can be covalently linked to N-acetylmuramic acid or a terminal D-alanine in the tetrapeptide crosslinkage between N-acetylmuramic acid units of the peptidoglycan layer, or they can be anchored in the cytoplasmic membrane with a lipid anchor. Teichoic acid's chemical signal is CH17P4O29NOH.
Teichoic acids that are anchored to the lipid membrane are referred to as lipoteichoic acids (LTAs), whereas teichoic acids that are covalently bound to peptidoglycan are referred to as wall teichoic acids (WTA).
Structure
The most common structure of Wall teichoic acids are a ManNAc(β1→4)GlcNAc disaccharide with one to three glycerol phosphates attached to the C4 hydroxyl of the ManNAc residue followed by a long chain of glycerol- or ribitol phosphate repeats. Variations come in the long chain tail, which generally include sugar subunits being attached to the sides or the body of the repeats. Four types of WTA repeats have been named, as of 2013.
Lipoteichoic acids follow a similar pattern of putting most variation in the repeats, although the set of enzymes used are different, at least in the case of Type I LTA. The repeats are anchored onto the membrane via a (di)glucosyl-diacylglycerol (Glc(2)DAG) anchor. Type IV LTA from Streptococcus pneumoniae represents a special case where both types intersect: after the tail is synthesized with an undecaprenyl phosphate (C55-P) intermediate "head", different TagU/LCP (LytR-CpsA-Psr) family enzymes either attaches it to the wal |
https://en.wikipedia.org/wiki/Glide%20reflection | In 2-dimensional geometry, a glide reflection (or transflection) is a symmetry operation that consists of a reflection over a line and then translation along that line, combined into a single operation. The intermediate step between reflection and translation can look different from the starting configuration, so objects with glide symmetry are in general, not symmetrical under reflection alone. In group theory, the glide plane is classified as a type of opposite isometry of the Euclidean plane.
A single glide is represented as frieze group p11g. A glide reflection can be seen as a limiting rotoreflection, where the rotation becomes a translation. It can also be given a Schoenflies notation as S2∞, Coxeter notation as [∞+,2+], and orbifold notation as ∞×.
Description
The combination of a reflection in a line and a translation in a perpendicular direction is a reflection in a parallel line. However, a glide reflection cannot be reduced like that. Thus the effect of a reflection combined with any translation is a glide reflection, with as special case just a reflection. These are the two kinds of indirect isometries in 2D.
For example, there is an isometry consisting of the reflection on the x-axis, followed by translation of one unit parallel to it. In coordinates, it takes
This isometry maps the x-axis to itself; any other line which is parallel to the x-axis gets reflected in the x-axis, so this system of parallel lines is left invariant.
The isometry group generated by just a glide reflection is an infinite cyclic group.
Combining two equal glide reflections gives a pure translation with a translation vector that is twice that of the glide reflection, so the even powers of the glide reflection form a translation group.
In the case of glide reflection symmetry, the symmetry group of an object contains a glide reflection, and hence the group generated by it. If that is all it contains, this type is frieze group p11g.
Example pattern with this symmetry group |
https://en.wikipedia.org/wiki/Folding%40home | Folding@home (FAH or F@h) is a distributed computing project aimed to help scientists develop new therapeutics for a variety of diseases by the means of simulating protein dynamics. This includes the process of protein folding and the movements of proteins, and is reliant on simulations run on volunteers' personal computers. Folding@home is currently based at the University of Pennsylvania and led by Greg Bowman, a former student of Vijay Pande.
The project utilizes graphics processing units (GPUs), central processing units (CPUs), and ARM processors like those on the Raspberry Pi for distributed computing and scientific research. The project uses statistical simulation methodology that is a paradigm shift from traditional computing methods. As part of the client–server model network architecture, the volunteered machines each receive pieces of a simulation (work units), complete them, and return them to the project's database servers, where the units are compiled into an overall simulation. Volunteers can track their contributions on the Folding@home website, which makes volunteers' participation competitive and encourages long-term involvement.
Folding@home is one of the world's fastest computing systems. With heightened interest in the project as a result of the COVID-19 pandemic, the system achieved a speed of approximately 1.22 exaflops by late March 2020 and reached 2.43 exaflops by April 12, 2020, making it the world's first exaflop computing system. This level of performance from its large-scale computing network has allowed researchers to run computationally costly atomic-level simulations of protein folding thousands of times longer than formerly achieved. Since its launch on October 1, 2000, Folding@home was involved in the production of 226 scientific research papers. Results from the project's simulations agree well with experiments.
Background
Proteins are an essential component to many biological functions and participate in virtually all process |
https://en.wikipedia.org/wiki/QRIO | QRIO ("Quest for cuRIOsity", originally named Sony Dream Robot or SDR) was a bipedal humanoid entertainment robot developed and marketed (but never sold) by Sony to follow up on the success of its AIBO entertainment robot. QRIO stood approximately 0.6 m (2 feet) tall and weighed 7.3 kg (16 pounds). QRIO's slogan was "Makes life fun, makes you happy!"
On January 26, 2006, on the same day as it announced its discontinuation of AIBO and other products, Sony announced that it would stop development of QRIO. Before it was cancelled, QRIO was reported to be going through numerous development, testing and scalability phases, with the intent of becoming commercially available within three or four years.
Development
The QRIO prototypes were developed and manufactured by Sony Intelligence Dynamics Laboratory, Inc. The number of these prototypes in existence is unknown. Up to ten QRIO have been seen performing a dance routine together; this was confirmed by a Sony representative at the Museum of Science in Boston, MA on January 22, 2006. Numerous videos of this can be found on the web.
Four fourth-generation QRIO prototype robots were featured dancing in the Hell Yes music video by recording artist Beck. These prototypes lacked a third camera in the center of the forehead and the improved hands and wrists which were added to later prototypes. It took programmers three weeks to program their choreography.
QRIO is capable of voice and face recognition, making it able to remember people as well as their likes and dislikes. A video on QRIO's website shows it speaking with several children. QRIO can run at 23 cm/s, and is credited in Guinness World Records (2005 edition) as being the first bipedal robot capable of running (which it defines as moving while both legs are off the ground at the same time). The 4th generation QRIO's internal battery lasts about 1 hour.
In popular culture
In 2005, four QRIO robots appeared in the music video for "Hell Yes" by Beck. The robots dance |
https://en.wikipedia.org/wiki/Pincherle%20derivative | In mathematics, the Pincherle derivative of a linear operator on the vector space of polynomials in the variable x over a field is the commutator of with the multiplication by x in the algebra of endomorphisms . That is, is another linear operator
(for the origin of the notation, see the article on the adjoint representation) so that
This concept is named after the Italian mathematician Salvatore Pincherle (1853–1936).
Properties
The Pincherle derivative, like any commutator, is a derivation, meaning it satisfies the sum and products rules: given two linear operators and belonging to
;
where is the composition of operators.
One also has where is the usual Lie bracket, which follows from the Jacobi identity.
The usual derivative, D = d/dx, is an operator on polynomials. By straightforward computation, its Pincherle derivative is
This formula generalizes to
by induction. This proves that the Pincherle derivative of a differential operator
is also a differential operator, so that the Pincherle derivative is a derivation of .
When has characteristic zero, the shift operator
can be written as
by the Taylor formula. Its Pincherle derivative is then
In other words, the shift operators are eigenvectors of the Pincherle derivative, whose spectrum is the whole space of scalars .
If T is shift-equivariant, that is, if T commutes with Sh or , then we also have , so that is also shift-equivariant and for the same shift .
The "discrete-time delta operator"
is the operator
whose Pincherle derivative is the shift operator .
See also
Commutator
Delta operator
Umbral calculus
References
External links
Weisstein, Eric W. "Pincherle Derivative". From MathWorld—A Wolfram Web Resource.
Biography of Salvatore Pincherle at the MacTutor History of Mathematics archive.
Differential algebra |
https://en.wikipedia.org/wiki/Storm%20drain | A storm drain, storm sewer (United Kingdom, U.S. and Canada), surface water drain/sewer (United Kingdom), or stormwater drain (Australia and New Zealand) is infrastructure designed to drain excess rain and ground water from impervious surfaces such as paved streets, car parks, parking lots, footpaths, sidewalks, and roofs. Storm drains vary in design from small residential dry wells to large municipal systems.
Drains receive water from street gutters on most motorways, freeways and other busy roads, as well as towns in areas with heavy rainfall that leads to flooding, and coastal towns with regular storms. Even gutters from houses and buildings can connect to the storm drain. Many storm drainage systems are gravity sewers that drain untreated storm water into rivers or streams—so it is unacceptable to pour hazardous substances into the drains.
Storm drains sometimes cannot manage the quantity of rain that falls in heavy rains or storms. Inundated drains can cause basement and street flooding. Many areas require detention tanks inside a property that temporarily hold runoff in heavy rains and restrict outlet flow to the public sewer. This reduces the risk of overwhelming the public sewer. Some storm drains mix stormwater (rainwater) with sewage, either intentionally in the case of combined sewers, or unintentionally.
Nomenclature
Several related terms are used differently in American and British English.
Function
Inlet
There are two main types of stormwater drain (highway drain or road gully in the UK) inlets: side inlets and grated inlets. Side inlets are located adjacent to the curb and rely on the ability of the opening under the back stone or lintel to capture flow. They are usually depressed at the invert of the channel to improve capture capacity.
Many inlets have gratings or grids to prevent people, vehicles, large objects or debris from falling into the storm drain. Grate bars are spaced so that the flow of water is not impeded, but sediment and many |
https://en.wikipedia.org/wiki/Taximeter | A taximeter or fare meter is a mechanical or electronic device installed in taxicabs and auto rickshaws that calculates passenger fares based on a combination of distance travelled and waiting time. Its shortened form, "taxi", is also a metonym for the hired cars that use them.
History
The modern taximeter was invented by German Friedrich Wilhelm Gustav Bruhn in 1891, and the Daimler Victoria—the world's first meter-equipped (and gasoline-powered) taxicab—was built by Gottlieb Daimler in 1897.
Taximeters were originally mechanical and mounted outside the cab, above the driver's side front wheel. Meters were soon relocated inside the taxi, and in the 1980s electronic meters were introduced, doing away with the once-familiar ticking sound of the meter's timing mechanism.
In some locations, taxicabs display a small illuminated sign indicating if they are free (available). In Argentina, this sign is called a "banderita" (little flag), a carryover term from the days of mechanical taximeters, in which a little flag was turned to wind up the mechanism. The flag would be hidden at the start of a trip and moved to the visible position at the end.
World Moto developed the world's first portable taximeter for motorcycles and pedicabs, which Fast Company called "the First Real Taxi Meter Innovation in 100 Years".
k constant
Constant expressed in pulses per kilometre which represents the number of pulses the taximeter must receive in order to correctly indicate a distance traveled of one kilometre.
Functioning
Taximeters, when they are installed to the taxis, require adjustment of k constant. During the movement, car generates signal which transmitted to the taximeter. Number of signals transmitted per k constant ratio results distance travelled. Within pre-installed tariff values and travel data are multiplied and fare is calculated.
Accessories and features
Taximeters can include several accessories, or act as components in larger dispatching/control systems. Fe |
https://en.wikipedia.org/wiki/Q%2Abert | Q*bert (; also known as Qbert) is an arcade video game developed and published for the North American market by Gottlieb in 1982. It is a 2D action game with puzzle elements that uses isometric graphics to create a pseudo-3D effect. The objective of each level in the game is to change every cube in a pyramid to a target color by making Q*bert, the on-screen character, hop on top of the cube while avoiding obstacles and enemies. Players use a joystick to control the character.
The game was conceived by Warren Davis and Jeff Lee. Lee designed the title character and original concept, which was further developed and implemented by Davis. Q*bert was developed under the project name Cubes.
Q*bert was well-received in arcades and among critics. The game was Gottlieb's most successful video game and is among the most recognized brands from the golden age of arcade games. It has been ported to numerous platforms. The game's success resulted in sequels and the use of the character's likeness in merchandising, such as appearances on lunch boxes, toys, and an animated television show. The Q*bert character became known for his "swearing" and "Q*bertese sound" – an incoherent phrase made of synthesized speech generated by the sound chip and a speech balloon containing a grawlix that appear when he collides with an enemy.
Because the game was developed during the period when Columbia Pictures owned Gottlieb, the intellectual rights to Q*bert remained with Columbia, even after they divested themselves of Gottlieb's assets in 1984. Therefore, the rights have been owned by Sony Pictures Entertainment since its parent, Sony, acquired Columbia in 1989. Q*bert appeared in Disney's Wreck-It Ralph franchise, under license from Sony, and later appeared in the film Pixels.
Gameplay
Q*bert is an action game with puzzle elements played from an axonometric third-person perspective to convey a three-dimensional look. The game is played using a single, diagonally mounted four-way joystick. |
https://en.wikipedia.org/wiki/Amar%20Bose | Amar Gopal Bose (November 2, 1929 – July 12, 2013) was an American entrepreneur and academic. An electrical engineer and sound engineer, he was a professor at the Massachusetts Institute of Technology for over 45 years. He was also the founder and chairman of Bose Corporation.
In 2011, he donated a majority of the company to MIT in the form of non-voting shares to sustain and advance MIT's education and research mission.
Early life and education
Bose was born in Philadelphia, Pennsylvania, to an Bengali Indian father, Noni Gopal Bose and an American mother, Charlotte Mechlin (1895-1973). His mother was a schoolteacher of French and German ancestry. His father was an Indian independence activist who, having been imprisoned for his political activities, fled Bengal in the 1920s in order to avoid further persecution by the British colonial police.
Bose first displayed his entrepreneurial skills and his interest in electronics at age thirteen when, during the World War II years, he enlisted school friends as co-workers in a small home business repairing model trains and home radios, to supplement his family's income.
After graduating from Abington Senior High School in Abington, Pennsylvania, Bose enrolled at the Massachusetts Institute of Technology, graduating with a BS (Bachelor of Science) in Electrical Engineering in the early 1950s. Bose spent a year at Philips Natuurkundig Laboratorium in Eindhoven, Netherlands; and a year as a Fulbright research student in New Delhi, India, where he met his future first wife. He completed his PhD in Electrical Engineering from MIT, writing a thesis on non-linear systems under the supervision of Norbert Wiener and Yuk-Wing Lee.
Career
Following graduation, Amar Bose became an assistant professor at the Massachusetts Institute of Technology. During his early years as a professor, Bose bought a high-end stereo speaker system in 1956 and he was disappointed to find that speakers with impressive technical specifications failed |
https://en.wikipedia.org/wiki/Stapler | A stapler is a mechanical device that joins pages of paper or similar material by driving a thin metal staple through the sheets and folding the ends. Staplers are widely used in government, business, offices, work places, homes and schools.
The word "stapler" can actually refer to a number of different devices of varying uses. In addition to joining paper sheets together, staplers can also be used in a surgical setting to join tissue together with surgical staples to close a surgical wound (much in the same way as sutures).
Most staplers are used to join multiple sheets of paper. Paper staplers come in two distinct types: manual and electric. Manual staplers are normally hand-held, although models that are used while set on a desk or other surface are not uncommon. Electric staplers exist in a variety of different designs and models. Their primary operating function is to join large numbers of paper sheets together in rapid succession. Some electric staplers can join up to 20 sheets at a time. Typical staplers are a third-class lever.
History
The growing uses of paper in the 19th century created a demand for an efficient paper fastener.
In 1866, George McGill received U.S. patent 56,587 for a small, bendable brass paper fastener that was a precursor to the modern staple. In 1867, he received U.S. patent 67,665 for a press to insert the fastener into paper. He showed his invention at the 1876 Centennial Exhibition in Philadelphia, Pennsylvania, and continued to work on these and other various paper fasteners throughout the 1880s. In 1868 an English patent for a stapler was awarded to C. H. Gould, and in the U.S, Albert Kletzker of St. Louis, MO also patented a device.
In 1877 Henry R. Heyl filed patent number 195,603 for the first machines to both insert and clinch a staple in one step, and for this reason some consider him the inventor of the modern stapler. In 1876 and 1877 Heyl also filed patents for the Novelty Paper Box Manufacturing Co. of Philadelphia, |
https://en.wikipedia.org/wiki/Sterilization%20%28microbiology%29 | Sterilization (or sterilisation) refers to any process that removes, kills, or deactivates all forms of life (particularly microorganisms such as fungi, bacteria, spores, and unicellular eukaryotic organisms) and other biological agents such as prions present in or on a specific surface, object, or fluid. Sterilization can be achieved through various means, including heat, chemicals, irradiation, high pressure, and filtration. Sterilization is distinct from disinfection, sanitization, and pasteurization, in that those methods reduce rather than eliminate all forms of life and biological agents present. After sterilization, an object is referred to as being sterile or aseptic.
Applications
Foods
One of the first steps toward modernized sterilization was made by Nicolas Appert, who discovered that application of heat over a suitable period slowed the decay of foods and various liquids, preserving them for safe consumption for a longer time than was typical. Canning of foods is an extension of the same principle and has helped to reduce food borne illness ("food poisoning"). Other methods of sterilizing foods include food irradiation and high pressure (pascalization).
Medicine and surgery
In general, surgical instruments and medications that enter an already aseptic part of the body (such as the bloodstream, or penetrating the skin) must be sterile. Examples of such instruments include scalpels, hypodermic needles, and artificial pacemakers. This is also essential in the manufacture of parenteral pharmaceuticals.
Preparation of injectable medications and intravenous solutions for fluid replacement therapy requires not only sterility but also well-designed containers to prevent entry of adventitious agents after initial product sterilization.
Most medical and surgical devices used in healthcare facilities are made of materials that are able to go under steam sterilization. However, since 1950, there has been an increase in medical devices and instruments made of m |
https://en.wikipedia.org/wiki/Sum-addressed%20decoder | In CPU design, the use of a sum-addressed decoder (SAD) or sum-addressed memory (SAM) decoder is a method of reducing the latency of the CPU cache access and address calculation (base + offset). This is achieved by fusing the address generation sum operation with the decode operation in the cache SRAM.
Overview
The L1 data cache should usually be in the most critical CPU resource, because few things improve instructions per cycle (IPC) as directly as a larger data cache, a larger data cache takes longer to access, and pipelining the data cache makes IPC worse. One way of reducing the latency of the L1 data cache access is by fusing the address generation sum operation with the decode operation in the cache SRAM.
The address generation sum operation still must be performed, because other units in the memory pipe will use the resulting virtual address. That sum will be performed in parallel with the fused add/decode described here.
The most profitable recurrence to accelerate is a load, followed by a use of that load in a chain of integer operations leading to another load. Assuming that load results are bypassed with the same priority as integer results, then it's possible to summarize this recurrence as a load followed by another load—as if the program was following a linked list.
The rest of this page assumes an instruction set architecture (ISA) with a single addressing mode (register+offset), a virtually indexed data cache, and sign-extending loads that may be variable-width. Most RISC ISAs fit this description. In ISAs such as the Intel x86, three or four inputs are summed to generate the virtual address. Multiple-input additions can be reduced to a two-input addition with carry save adders, and the remaining problem is as described below. The critical recurrence, then, is an adder, a decoder, the SRAM word line, the SRAM bit line(s), the sense amp(s), the byte steering muxes, and the bypass muxes.
For this example, a direct-mapped 16 KB data cache which re |
https://en.wikipedia.org/wiki/Paleobotany | Paleobotany, also spelled as palaeobotany, is the branch of botany dealing with the recovery and identification of plant remains from geological contexts, and their use for the biological reconstruction of past environments (paleogeography), and the evolutionary history of plants, with a bearing upon the evolution of life in general. A synonym is paleophytology. It is a component of paleontology and paleobiology. The prefix palaeo- or paleo- means "ancient, old", and is derived from the Greek adjective , . Paleobotany includes the study of terrestrial plant fossils, as well as the study of prehistoric marine photoautotrophs, such as photosynthetic algae, seaweeds or kelp. A closely related field is palynology, which is the study of fossilized and extant spores and pollen.
Paleobotany is important in the reconstruction of ancient ecological systems and climate, known as paleoecology and paleoclimatology respectively. It is fundamental to the study of green plant development and evolution. Paleobotany has also become important to the field of archaeology, primarily for the use of phytoliths in relative dating and in paleoethnobotany.
The emergence of paleobotany as a scientific discipline can be seen in the early 19th century, especially in the works of the German paleontologist Ernst Friedrich von Schlotheim, the Czech (Bohemian) nobleman and scholar Kaspar Maria von Sternberg, and the French botanist Adolphe-Théodore Brongniart.
Overview of the paleobotanical record
Macroscopic remains of true vascular plants are first found in the fossil record during the Silurian Period of the Paleozoic era. Some dispersed, fragmentary fossils of disputed affinity, primarily spores and cuticles, have been found in rocks from the Ordovician Period in Oman, and are thought to derive from liverwort- or moss-grade fossil plants.
An important early land plant fossil locality is the Rhynie chert, found outside the village of Rhynie in Scotland. The Rhynie chert is an Early Devonia |
https://en.wikipedia.org/wiki/Classic%20RISC%20pipeline | In the history of computer hardware, some early reduced instruction set computer central processing units (RISC CPUs) used a very similar architectural solution, now called a classic RISC pipeline. Those CPUs were: MIPS, SPARC, Motorola 88000, and later the notional CPU DLX invented for education.
Each of these classic scalar RISC designs fetches and tries to execute one instruction per cycle. The main common concept of each design is a five-stage execution instruction pipeline. During operation, each pipeline stage works on one instruction at a time. Each of these stages consists of a set of flip-flops to hold state, and combinational logic that operates on the outputs of those flip-flops.
The classic five stage RISC pipeline
Instruction fetch
The instructions reside in memory that takes one cycle to read. This memory can be dedicated to SRAM, or an Instruction Cache. The term "latency" is used in computer science often and means the time from when an operation starts until it completes. Thus, instruction fetch has a latency of one clock cycle (if using single-cycle SRAM or if the instruction was in the cache). Thus, during the Instruction Fetch stage, a 32-bit instruction is fetched from the instruction memory.
The Program Counter, or PC is a register that holds the address that is presented to the instruction memory. The address is presented to instruction memory at the start of a cycle. Then during the cycle, the instruction is read out of instruction memory, and at the same time, a calculation is done to determine the next PC. The next PC is calculated by incrementing the PC by 4, and by choosing whether to take that as the next PC or to take the result of a branch/jump calculation as the next PC. Note that in classic RISC, all instructions have the same length. (This is one thing that separates RISC from CISC ). In the original RISC designs, the size of an instruction is 4 bytes, so always add 4 to the instruction address, but don't use PC + 4 |
https://en.wikipedia.org/wiki/Rewriting | In mathematics, computer science, and logic, rewriting covers a wide range of methods of replacing subterms of a formula with other terms. Such methods may be achieved by rewriting systems (also known as rewrite systems, rewrite engines, or reduction systems). In their most basic form, they consist of a set of objects, plus relations on how to transform those objects.
Rewriting can be non-deterministic. One rule to rewrite a term could be applied in many different ways to that term, or more than one rule could be applicable. Rewriting systems then do not provide an algorithm for changing one term to another, but a set of possible rule applications. When combined with an appropriate algorithm, however, rewrite systems can be viewed as computer programs, and several theorem provers and declarative programming languages are based on term rewriting.
Example cases
Logic
In logic, the procedure for obtaining the conjunctive normal form (CNF) of a formula can be implemented as a rewriting system. The rules of an example of such a system would be:
(double negation elimination)
(De Morgan's laws)
(distributivity)
where the symbol () indicates that an expression matching the left hand side of the rule can be rewritten to one formed by the right hand side, and the symbols each denote a subexpression. In such a system, each rule is chosen so that the left side is equivalent to the right side, and consequently when the left side matches a subexpression, performing a rewrite of that subexpression from left to right maintains logical consistency and value of the entire expression.
Arithmetic
Term rewriting systems can be employed to compute arithmetic operations on natural numbers.
To this end, each such number has to be encoded as a term.
The simplest encoding is the one used in the Peano axioms, based on the constant 0 (zero) and the successor function S. For example, the numbers 0, 1, 2, and 3 are represented by the terms 0, S(0), S(S(0)), and S(S(S(0))), respective |
https://en.wikipedia.org/wiki/USS%20Pueblo%20%28AGER-2%29 | USS Pueblo (AGER-2) is a , placed into service during World War II, then converted to a spy ship in 1967 by the United States Navy. She gathered intelligence and oceanographic information, monitoring electronic and radio signals from North Korea. On 23 January 1968, the ship was attacked and captured by a North Korean vessel, in what became known as the "Pueblo incident", or alternatively, as the "Pueblo crisis'''".
The seizure of the U.S. Navy ship and her 83 crew members, one of whom was killed in the attack, came less than a week after President Lyndon B. Johnson's State of the Union address to the United States Congress, a week before the start of the Tet Offensive in South Vietnam during the Vietnam War and three days after 31 men of North Korea's KPA Unit 124 had crossed the Korean Demilitarized Zone (DMZ) and killed 26 South Koreans and 4 Americans in an attempt to attack the South Korean Blue House (executive mansion) in the capital Seoul. The taking of Pueblo and the abuse and torture of her crew during the next eleven months became a major Cold War incident, raising tensions between western and eastern powers.
North Korea stated that Pueblo deliberately entered their territorial waters away from Ryo Island, and that the logbook shows that they intruded several times. However, the United States maintained that the vessel was in international waters at the time of the incident and that any purported evidence supplied by North Korea to support its statements was fabricated. Pueblo remains held in North Korea, officially a commissioned vessel of the United States Navy.
Since early 2013, the ship has been moored along the Pothonggang Canal in Pyongyang and is displayed there as a museum ship at the Victorious War Museum. Pueblo is the only ship of the U.S. Navy still on the commissioned roster and held captive.
Initial operations
The ship was launched at the Kewaunee Shipbuilding and Engineering Company in Kewaunee, Wisconsin, on 16 April 1944, as the Uni |
https://en.wikipedia.org/wiki/Xenobiotic | A xenobiotic is a chemical substance found within an organism that is not naturally produced or expected to be present within the organism. It can also cover substances that are present in much higher concentrations than are usual. Natural compounds can also become xenobiotics if they are taken up by another organism, such as the uptake of natural human hormones by fish found downstream of sewage treatment plant outfalls, or the chemical defenses produced by some organisms as protection against predators.
The term xenobiotics, however, is very often used in the context of pollutants such as dioxins and polychlorinated biphenyls and their effect on the biota, because xenobiotics are understood as substances foreign to an entire biological system, i.e. artificial substances, which did not exist in nature before their synthesis by humans. The term xenobiotic is derived from the Greek words ξένος (xenos) = foreigner, stranger and βίος (bios) = life, plus the Greek suffix for adjectives -τικός, -ή, -όν (-tikos, -ē, -on).
Xenobiotics may be grouped as carcinogens, drugs, environmental pollutants, food additives, hydrocarbons, and pesticides.
Xenobiotic metabolism
The body removes xenobiotics by xenobiotic metabolism. This consists of the deactivation and the excretion of xenobiotics and happens mostly in the liver. Excretion routes are urine, feces, breath, and sweat. Hepatic enzymes are responsible for the metabolism of xenobiotics by first activating them (oxidation, reduction, hydrolysis, and/or hydration of the xenobiotic), and then conjugating the active secondary metabolite with glucuronic acid, sulfuric acid, or glutathione, followed by excretion in bile or urine. An example of a group of enzymes involved in xenobiotic metabolism is hepatic microsomal cytochrome P450. These enzymes that metabolize xenobiotics are very important for the pharmaceutical industry because they are responsible for the breakdown of medications. A species with this unique cytochrome P |
https://en.wikipedia.org/wiki/Branch%20predictor | In computer architecture, a branch predictor is a digital circuit that tries to guess which way a branch (e.g., an if–then–else structure) will go before this is known definitively. The purpose of the branch predictor is to improve the flow in the instruction pipeline. Branch predictors play a critical role in achieving high performance in many modern pipelined microprocessor architectures.
Two-way branching is usually implemented with a conditional jump instruction. A conditional jump can either be "taken" and jump to a different place in program memory, or it can be "not taken" and continue execution immediately after the conditional jump. It is not known for certain whether a conditional jump will be taken or not taken until the condition has been calculated and the conditional jump has passed the execution stage in the instruction pipeline (see fig. 1).
Without branch prediction, the processor would have to wait until the conditional jump instruction has passed the execute stage before the next instruction can enter the fetch stage in the pipeline. The branch predictor attempts to avoid this waste of time by trying to guess whether the conditional jump is most likely to be taken or not taken. The branch that is guessed to be the most likely is then fetched and speculatively executed. If it is later detected that the guess was wrong, then the speculatively executed or partially executed instructions are discarded and the pipeline starts over with the correct branch, incurring a delay.
The time that is wasted in case of a branch misprediction is equal to the number of stages in the pipeline from the fetch stage to the execute stage. Modern microprocessors tend to have quite long pipelines so that the misprediction delay is between 10 and 20 clock cycles. As a result, making a pipeline longer increases the need for a more advanced branch predictor.
The first time a conditional jump instruction is encountered, there is not much information to base a prediction |
https://en.wikipedia.org/wiki/Rice%20paper | "Rice paper" has many varieties such as rice paper made from tree bark to make drawing and writing paper or from rice flour and tapioca flour and then mixed with salt and water to produce a thin rice cake and dried to become harder and paper-like. It is used to wrap many ingredients when eating. Vietnam is the only country that creates edible rice paper from the process of making rice noodles and pho noodles.
Rice paper is a product constructed of paper-like materials made from different plants. These include:
Thin peeled dried pith of Tetrapanax papyrifer: A sheet-like "paper" material was used extensively in late 19th century Guangdong, China, as a common support medium for gouache paintings sold to Western clients of the era. The term was first defined in the Chinese–English Dictionary of Robert Morrison who referred to the use of the Chinese medicinal plant as material for painting, as well as for making artificial flowers and shoe soles.
Xuan paper made from paper mulberry: The traditional paper which originated in ancient China and it has been used for centuries in China, Japan, Korea, and Vietnam for writing, artwork, and architecture.
Various pulp-based papers: May be made from the rice straw or other plants, such as hemp and bamboo.
Dried starch sheets of various thickness or texture: These edible paper sheets have some properties of pulp paper and can be made from rice starch. They are known as bánh tráng, used in Vietnamese cuisine.
Rice paper plant
In Europe, around the 1900s, a paperlike substance was originally known as rice paper, due to the mistaken notion that it is made from rice. In fact, it consists of the pith of a small tree, Tetrapanax papyrifer, the rice paper plant (蓪草).
The plant grows in the swampy forests of Taiwan, and is also cultivated as an ornamental plant for its large, exotic leaves. In order to produce the paper, the boughs are boiled and freed from bark. The cylindrical core of pith is rolled on a hard flat surface against a kn |
https://en.wikipedia.org/wiki/List%20of%20dominance%20hierarchy%20species | Dominance hierarchies occur in many social animals.
Primates
Researcher M. W. Foster investigated primates and found that the leaders were more likely to be those who did more for those around them instead of being determined by strength.
Baboons
Alpha male baboons monopolize resources and mating access to females, and they are also more likely to suffer from stress. Lower status males must expend more time and energy for mating opportunities. Alpha males may sometimes allow subordinate males to have access to mating, so the subordinate males can serve as "spare dads" and protect their offspring from other alpha males.
Capuchin monkeys
A study on the association of alpha males and females during the non-breeding season in wild Capuchin monkeys (Cebus apella nigritus) examined whether alpha males are the preferred mate for females and, secondly, whether female-alpha status and relationship to the alpha-male can be explained through the individual characteristics and or social network of the female. The results indicated that alpha male Capuchin are the preferred mate for adult females. However, only the alpha females had strong interactions with the alpha males by virtue of a dominance hierarchy among the females in which only the most dominant and strong females were able to interact with the alpha male.
Chimpanzees
Common chimpanzees use strength, intelligence, and political alliances to establish and maintain alpha position. There have been rare cases where a group has killed the alpha male.
Common chimpanzees show deference to the alpha of the community by ritualized postures and gestures such as presenting their back, crouching, bowing, or bobbing. Chimpanzees lower in rank than the alpha male will offer their hand while grunting to the alpha male as a sign of submission. Bonobo society on the other hand is governed by alpha females. Males will associate with females for rank acquisition because females dominate the social environment. If a male is to a |
https://en.wikipedia.org/wiki/Cross-validation%20%28statistics%29 | Cross-validation, sometimes called rotation estimation or out-of-sample testing, is any of various similar model validation techniques for assessing how the results of a statistical analysis will generalize to an independent data set.
Cross-validation is a resampling method that uses different portions of the data to test and train a model on different iterations. It is mainly used in settings where the goal is prediction, and one wants to estimate how accurately a predictive model will perform in practice. In a prediction problem, a model is usually given a dataset of known data on which training is run (training dataset), and a dataset of unknown data (or first seen data) against which the model is tested (called the validation dataset or testing set). The goal of cross-validation is to test the model's ability to predict new data that was not used in estimating it, in order to flag problems like overfitting or selection bias and to give an insight on how the model will generalize to an independent dataset (i.e., an unknown dataset, for instance from a real problem).
One round of cross-validation involves partitioning a sample of data into complementary subsets, performing the analysis on one subset (called the training set), and validating the analysis on the other subset (called the validation set or testing set). To reduce variability, in most methods multiple rounds of cross-validation are performed using different partitions, and the validation results are combined (e.g. averaged) over the rounds to give an estimate of the model's predictive performance.
In summary, cross-validation combines (averages) measures of fitness in prediction to derive a more accurate estimate of model prediction performance.
Motivation
Assume a model with one or more unknown parameters, and a data set to which the model can be fit (the training data set). The fitting process optimizes the model parameters to make the model fit the training data as well as possible. If an ind |
https://en.wikipedia.org/wiki/Application%20checkpointing | Checkpointing is a technique that provides fault tolerance for computing systems. It basically consists of saving a snapshot of the application's state, so that applications can restart from that point in case of failure. This is particularly important for long running applications that are executed in failure-prone computing systems.
Checkpointing in distributed systems
In the distributed computing environment, checkpointing is a technique that helps tolerate failures that otherwise would force long-running application to restart from the beginning. The most basic way to implement checkpointing, is to stop the application, copy all the required data from the memory to reliable storage (e.g., parallel file system) and then continue with the execution. In case of failure, when the application restarts, it does not need to start from scratch. Rather, it will read the latest state ("the checkpoint") from the stable storage and execute from that. While there is ongoing debate on whether checkpointing is the dominating I/O workload on distributed computing systems, there is general consensus that checkpointing is one of the major I/O workloads.
There are two main approaches for checkpointing in the distributed computing systems: coordinated checkpointing and uncoordinated checkpointing. In the coordinated checkpointing approach, processes must ensure that their checkpoints are consistent. This is usually achieved by some kind of two-phase commit protocol algorithm. In the uncoordinated checkpointing, each process checkpoints its own state independently. It must be stressed that simply forcing processes to checkpoint their state at fixed time intervals is not sufficient to ensure global consistency. The need for establishing a consistent state (i.e., no missing messages or duplicated messages) may force other processes to roll back to their checkpoints, which in turn may cause other processes to roll back to even earlier checkpoints, which in the most extreme case ma |
https://en.wikipedia.org/wiki/Timeline%20of%20algorithms | The following timeline of algorithms outlines the development of algorithms (mainly "mathematical recipes") since their inception.
Medieval Period
Before – writing about "recipes" (on cooking, rituals, agriculture and other themes)
c. 1700–2000 BC – Egyptians develop earliest known algorithms for multiplying two numbers
c. 1600 BC – Babylonians develop earliest known algorithms for factorization and finding square roots
c. 300 BC – Euclid's algorithm
c. 200 BC – the Sieve of Eratosthenes
263 AD – Gaussian elimination described by Liu Hui
628 – Chakravala method described by Brahmagupta
c. 820 – Al-Khawarizmi described algorithms for solving linear equations and quadratic equations in his Algebra; the word algorithm comes from his name
825 – Al-Khawarizmi described the algorism, algorithms for using the Hindu–Arabic numeral system, in his treatise On the Calculation with Hindu Numerals, which was translated into Latin as Algoritmi de numero Indorum, where "Algoritmi", the translator's rendition of the author's name gave rise to the word algorithm (Latin algorithmus) with a meaning "calculation method"
c. 850 – cryptanalysis and frequency analysis algorithms developed by Al-Kindi (Alkindus) in A Manuscript on Deciphering Cryptographic Messages, which contains algorithms on breaking encryptions and ciphers
c. 1025 – Ibn al-Haytham (Alhazen), was the first mathematician to derive the formula for the sum of the fourth powers, and in turn, he develops an algorithm for determining the general formula for the sum of any integral powers, which was fundamental to the development of integral calculus
c. 1400 – Ahmad al-Qalqashandi gives a list of ciphers in his Subh al-a'sha which include both substitution and transposition, and for the first time, a cipher with multiple substitutions for each plaintext letter; he also gives an exposition on and worked example of cryptanalysis, including the use of tables of letter frequencies and sets of letters which can not occ |
https://en.wikipedia.org/wiki/Physical%20Address%20Extension | In computing, Physical Address Extension (PAE), sometimes referred to as Page Address Extension,
is a memory management feature for the x86 architecture. PAE was first introduced by Intel in the Pentium Pro, and later by AMD in the Athlon processor. It defines a page table hierarchy of three levels (instead of two), with table entries of 64 bits each instead of 32, allowing these CPUs to directly access a physical address space larger than 4 gigabytes (232 bytes).
The page table structure used by x86-64 CPUs when operating in long mode further extends the page table hierarchy to four or more levels, extending the virtual address space, and uses additional physical address bits at all levels of the page table, extending the physical address space. It also uses the topmost bit of the 64-bit page table entry as a no-execute or "NX" bit, indicating that code cannot be executed from the associated page. The NX feature is also available in protected mode when these CPUs are running a 32-bit operating system, provided that the operating system enables PAE.
History
PAE was first implemented in the Intel Pentium Pro in 1995, although the accompanying chipsets usually lacked support for the required extra address bits.
PAE is supported by the Pentium Pro, Pentium II, Pentium III, and Pentium 4 processors. The first Pentium M family processors ("Banias") introduced in 2003 also support PAE; however, they do not show the PAE support flag in their CPUID information. This was remedied in a later revision of the "Dothan" core in 2005. It was also available on AMD processors including the AMD Athlon (although the chipsets are limited to 32-bit addressing) and later AMD processor models.
When AMD defined their 64-bit extension of the industry standard x86 architecture, AMD64 or x86-64, they also enhanced the paging system in "long mode" based on PAE.
It supports 64-bit virtual addresses ( 48 bits are implemented on some processors and 57 bits are implemented on others), 52-b |
https://en.wikipedia.org/wiki/Square%20triangular%20number | In mathematics, a square triangular number (or triangular square number) is a number which is both a triangular number and a square number. There are infinitely many square triangular numbers; the first few are:
0, 1, 36, , , , , , ,
Explicit formulas
Write for the th square triangular number, and write and for the sides of the corresponding square and triangle, so that
Define the triangular root of a triangular number to be . From this definition and the quadratic formula,
Therefore, is triangular ( is an integer) if and only if is square. Consequently, a square number is also triangular if and only if is square, that is, there are numbers and such that . This is an instance of the Pell equation with . All Pell equations have the trivial solution for any ; this is called the zeroth solution, and indexed as . If denotes the th nontrivial solution to any Pell equation for a particular , it can be shown by the method of descent that
Hence there are an infinity of solutions to any Pell equation for which there is one non-trivial one, which holds whenever is not a square. The first non-trivial solution when is easy to find: it is (3,1). A solution to the Pell equation for yields a square triangular number and its square and triangular roots as follows:
Hence, the first square triangular number, derived from (3,1), is 1, and the next, derived from , is 36.
The sequences , and are the OEIS sequences , , and respectively.
In 1778 Leonhard Euler determined the explicit formula
Other equivalent formulas (obtained by expanding this formula) that may be convenient include
The corresponding explicit formulas for and are:
Pell's equation
The problem of finding square triangular numbers reduces to Pell's equation in the following way.
Every triangular number is of the form . Therefore we seek integers , such that
Rearranging, this becomes
and then letting and , we get the Diophantine equation
which is an instance of Pell's equation. This pa |
https://en.wikipedia.org/wiki/ONERA | The Office national d'études et de recherches aérospatiales (ONERA) is the French national aerospace research centre. It is a public establishment with industrial and commercial operations, and carries out application-oriented research to support enhanced innovation and competitiveness in the aerospace and defense sectors.
ONERA was created in 1946 as "Office National d’Études et de Recherches Aéronautiques". Since 1963, its official name has been "Office National d’Études et de Recherches Aérospatiales". However, in January 2007, ONERA has been dubbed "The French Aerospace Lab" to improve its international visibility.
History
ONERA's historic roots are in the Paris suburb of Meudon, south of Paris. As early as 1877, the Chalais-Meudon site hosted an aeronautical research center for military aerostats (balloons): Etablissement central de l’aérostation militaire.
ONERA was created in May 1946 to relaunch aeronautics research, an activity that had gone into hibernation during the Second World War and the German occupation. Its creation reflected the government's decision to recover the large wind tunnel in Ötztal, Austria, in the French administrative zone, and move it to France. Today, ONERA's extensive array of wind tunnels is one of its main assets. ONERA operates a world-class fleet of wind tunnels, the largest in Europe. The S1MA wind tunnel at Modane-Avrieux, developing 88 MW of total power, is Europe's largest transonic wind tunnel (tests at Mach 0.05 to Mach 1).
Organization
The Chairman and CEO of ONERA is appointed by the French Council of Ministers, acting on a proposal by the Minister of Defense. Since June 2014, the Chairman and CEO is Bruno Sainjon.
ONERA is organized in eight geographic areas. It has about 2,000 employees, with 1,500 engineers and scientists (including 230 doctoral candidates), as well as support staff.
Three centers in the greater Paris area (Ile-de-France):
Palaiseau, current headquarters
Châtillon
Meudon
Two centers in th |
https://en.wikipedia.org/wiki/Viral%20evolution | Viral evolution is a subfield of evolutionary biology and virology that is specifically concerned with the evolution of viruses. Viruses have short generation times, and many—in particular RNA viruses—have relatively high mutation rates (on the order of one point mutation or more per genome per round of replication). Although most viral mutations confer no benefit and often even prove deleterious to viruses, the rapid rate of viral mutation combined with natural selection allows viruses to quickly adapt to changes in their host environment. In addition, because viruses typically produce many copies in an infected host, mutated genes can be passed on to many offspring quickly. Although the chance of mutations and evolution can change depending on the type of virus (e.g., double stranded DNA, double stranded RNA, single strand DNA), viruses overall have high chances for mutations.
Viral evolution is an important aspect of the epidemiology of viral diseases such as influenza (influenza virus), AIDS (HIV), and hepatitis (e.g. HCV). The rapidity of viral mutation also causes problems in the development of successful vaccines and antiviral drugs, as resistant mutations often appear within weeks or months after the beginning of a treatment. One of the main theoretical models applied to viral evolution is the quasispecies model, which defines a viral quasispecies as a group of closely related viral strains competing within an environment.
Origins
Three classical hypotheses
Viruses are ancient. Studies at the molecular level have revealed relationships between viruses infecting organisms from each of the three domains of life, suggesting viral proteins that pre-date the divergence of life and thus infecting the last universal common ancestor. This indicates that some viruses emerged early in the evolution of life, and that they have probably arisen multiple times. It has been suggested that new groups of viruses have repeatedly emerged at all stages of evolution, often t |
https://en.wikipedia.org/wiki/Passive%20transport | Passive transport is a type of membrane transport that does not require energy to move substances across cell membranes. Instead of using cellular energy, like active transport, passive transport relies on the second law of thermodynamics to drive the movement of substances across cell membranes. Fundamentally, substances follow Fick's first law, and move from an area of high concentration to an area of low concentration because this movement increases the entropy of the overall system. The rate of passive transport depends on the permeability of the cell membrane, which, in turn, depends on the organization and characteristics of the membrane lipids and proteins. The four main kinds of passive transport are simple diffusion, facilitated diffusion, filtration, and/or osmosis.
Passive transport follows Fick's first law.
Diffusion
Diffusion is the net movement of material from an area of high concentration to an area with lower concentration. The difference of concentration between the two areas is often termed as the concentration gradient, and diffusion will continue until this gradient has been eliminated. Since diffusion moves materials from an area of higher concentration to an area of lower concentration, it is described as moving solutes "down the concentration gradient" (compared with active transport, which often moves material from area of low concentration to area of higher concentration, and therefore referred to as moving the material "against the concentration gradient").
However, in many cases (e.g. passive drug transport) the driving force of passive transport can not be simplified to the concentration gradient. If there are different solutions at the two sides of the membrane with different equilibrium solubility of the drug, the difference in the degree of saturation is the driving force of passive membrane transport. It is also true for supersaturated solutions which are more and more important owing to the spreading of the application of amorph |
https://en.wikipedia.org/wiki/Java%20Desktop%20System | Java Desktop System, briefly known as OpenSolaris Desktop, is a legacy desktop environment developed first by Sun Microsystems and then by Oracle Corporation after the 2010 Oracle acquisition of Sun. Java Desktop System is available for Solaris and was once available for Linux. The Linux version was discontinued after Solaris was released as open source software in 2005. Java Desktop System aims to provide a system familiar to the average computer user with a full suite of office productivity software such as an office suite, a web browser, email, calendaring, and instant messaging.
Despite being known as the Java Desktop System, it is not actually written in Java. Rather, it is built around a modified version of GNOME along with other common free software projects, which are written mostly in C and C++. The name reflected Sun's promotion of the product as an outlet for corporate users to deploy software written for the Java platform.
Versions
Sun first bundled a preview release of GNOME 1.4 on a separate CD for Solaris 8.
JDS version 2 included:
Java
GNOME (using the Blueprint theme)
StarOffice
Mozilla
Evolution
MP3 and CD player
Java Media Framework's Java Media Player
Gaim multi-service instant messaging
RealPlayer
JDS Release 2 was available for Solaris and for the SuSE-based Linux distribution.
JDS Release 3 was released in 2005. It was included with Solaris 10 — upon installation of Solaris, one has the choice of using either the CDE or JDS. It was based on GNOME 2.6 and available only for the Solaris 10 platform.
OpenSolaris Desktop
OpenSolaris received its own version of the Java Desktop System. OpenSolaris Desktop was tied to the OpenSolaris operating system, and did not have its own release schedule.
OpenSolaris Desktop 01 (released October 28, 2005) was based on GNOME 2.10 and OpenSolaris Desktop 02 (released December 23, 2005) was based on GNOME 2.12. The last version was released with the release of OpenSolaris 2009.6, and was based on Gnome 2. |
https://en.wikipedia.org/wiki/Unreal%20Engine | Unreal Engine (UE) is a series of 3D computer graphics game engines developed by Epic Games, first showcased in the 1998 first-person shooter video game Unreal. Initially developed for PC first-person shooters, it has since been used in a variety of genres of games and has seen adoption by other industries, most notably the film and television industry. Unreal Engine is written in C++ and features a high degree of portability, supporting a wide range of desktop, mobile, console, and virtual reality platforms.
The latest generation, Unreal Engine 5, was launched in April 2022. Its source code is available on GitHub, and commercial use is granted based on a royalty model, with Epic charging 5% of revenues over US$1 million, which is waived for games published on the Epic Games Store. Epic has included features from acquired companies like Quixel in the engine, which is seen as helped by Fortnite's revenue.
In 2014, Unreal Engine was named the world's "most successful videogame engine" by Guinness World Records.
History
First generation
The first-generation Unreal Engine was developed by Tim Sweeney, the founder of Epic Games. Having created editing tools for his shareware games ZZT (1991) and Jill of the Jungle (1992), Sweeney began writing the engine in 1995 for the production of a game that would later become a first-person shooter known as Unreal. After years in development, it debuted with the game's release in 1998, although MicroProse and Legend Entertainment had access to the technology much earlier, licensing it in 1996. According to an interview, Sweeney wrote 90 percent of the code in the engine, including the graphics, tools, and networking system.
At first, the engine relied completely on software rendering, meaning the graphics calculations were handled by the central processing unit (CPU). However, over time, it was able to take advantage of the capabilities provided by dedicated graphics cards, focusing on the Glide API, specially designed for 3df |
https://en.wikipedia.org/wiki/Algorism | Algorism is the technique of performing basic arithmetic by writing numbers in place value form and applying a set of memorized rules and facts to the digits. One who practices algorism is known as an algorist. This positional notation system has largely superseded earlier calculation systems that used a different set of symbols for each numerical magnitude, such as Roman numerals, and in some cases required a device such as an abacus.
Etymology
The word algorism comes from the name Al-Khwārizmī (c. 780–850), a Persian mathematician, astronomer, geographer and scholar in the House of Wisdom in Baghdad, whose name means "the native of Khwarezm", which is now in modern-day Uzbekistan. He wrote a treatise in Arabic language in the 9th century, which was translated into Latin in the 12th century under the title Algoritmi de numero Indorum. This title means "Algoritmi on the numbers of the Indians", where "Algoritmi" was the translator's Latinization of Al-Khwarizmi's name. Al-Khwarizmi was the most widely read mathematician in Europe in the late Middle Ages, primarily through his other book, the Algebra. In late medieval Latin, algorismus, the corruption of his name, simply meant the "decimal number system" that is still the meaning of modern English algorism. During the 17th century, the French form for the word – but not its meaning – was changed to algorithm, following the model of the word logarithm, this form alluding to the ancient Greek . English adopted the French very soon afterwards, but it wasn't until the late 19th century that "algorithm" took on the meaning that it has in modern English. In English, it was first used about 1230 and then by Chaucer in 1391. Another early use of the word is from 1240, in a manual titled Carmen de Algorismo composed by Alexandre de Villedieu. It begins thus:
which translates as:
The word algorithm also derives from algorism, a generalization of the meaning to any set of rules specifying a computational procedure. Occasiona |
https://en.wikipedia.org/wiki/Telegraph%20sounder | A telegraph sounder is an antique electromechanical device used as a receiver on electrical telegraph lines during the 19th century. It was invented by Alfred Vail after 1850 to replace the previous receiving device, the cumbersome Morse register and was the first practical application of the electromagnet. When a telegraph message comes in it produces an audible "clicking" sound representing the short and long keypresses – "dots" and "dashes" – which are used to represent text characters in Morse code. A telegraph operator would translate the sounds into characters representing the telegraph message.
Telegraph networks, used from the 1850s to the 1970s to transmit text messages long distances, transmitted information by pulses of current of two different lengths, called "dots" and "dashes" which spelled out text messages in Morse code. A telegraph operator at the sending end of the line would create the message by tapping on a switch called a telegraph key, which rapidly connects and breaks the circuit to a battery, sending pulses of current down the line.
The telegraph sounder was used at the receiving end of the line to make the Morse code message audible. Its simple mechanism was similar to a relay. It consisted of an electromagnet attached to the telegraph line, with an iron armature near the magnet's pole balanced on a pivot, held up by a counterweight. When current flowed through the electromagnet's winding, it created a magnetic field which attracted the armature, pulling it down to the electromagnet, resulting in a "click" sound. When the current ended, the counterweight pulled the armature back up to its resting position, resulting in a "clack" sound. Thus, as the telegraph key at the sending end makes and breaks the contact, the sounder echoes the up and down state of the key.
It was important that a sounder make a sound both when the circuit was broken and when it was restored. This was necessary for the operator clearly to distinguish the l |
https://en.wikipedia.org/wiki/Flight%20engineer | A flight engineer (FE), also sometimes called an air engineer, is the member of an aircraft's flight crew who monitors and operates its complex aircraft systems. In the early era of aviation, the position was sometimes referred to as the "air mechanic". Flight engineers can still be found on some larger fixed-wing airplanes and helicopters. A similar crew position exists on some spacecraft. In most modern aircraft, their complex systems are both monitored and adjusted by electronic microprocessors and computers, resulting in the elimination of the flight engineer's position.
In earlier days, most larger aircraft were designed and built with a flight engineer's position. For U.S. civilian aircraft that require a flight engineer as part of the crew, the flight engineer must possess an FAA Flight Engineer Certificate with reciprocating, turboprop, or turbojet ratings appropriate to the aircraft. Whereas the four-engine Douglas DC-4 did not require a flight engineer, the FAA type certificates of subsequent four-engine reciprocating engine airplanes (Boeing 307 and 377, DC-6, DC-7, Constellation) and early two-, three- and four-engine jets (Boeing 707, 727, early 747s, DC-8, DC-10, L-1011, early A300s) required them. Smaller twinjets (DC-9, 737, BAC 1-11, Caravelle, Dassault Mercure) were never complex enough to require a flight engineer, while later large two, three, and four-engine jets (Airbus A310, A300-600, Boeing 767, MD-11, 747-400, and later) were designed with sufficient automation as to eliminate the need for the position.
History
In order to dedicate a person to monitor an aircraft's engines and its other critical flight systems, the position of "flight engineer" (FE) was created. The FE did not actually fly the airplane; instead, the FE's position had a specialized control panel allowing for the monitoring and control of various aircraft systems. The FE is therefore an integrated member of the flight deck crew who works in close coordination with the two p |
https://en.wikipedia.org/wiki/Resistor%E2%80%93transistor%20logic | Resistor–transistor logic (RTL), sometimes also known as transistor–resistor logic (TRL), is a class of digital circuits built using resistors as the input network and bipolar junction transistors (BJTs) as switching devices. RTL is the earliest class of transistorized digital logic circuit; it was succeeded by diode–transistor logic (DTL) and transistor–transistor logic (TTL).
RTL circuits were first constructed with discrete components, but in 1961 it became the first digital logic family to be produced as a monolithic integrated circuit. RTL integrated circuits were used in the Apollo Guidance Computer, whose design began in 1961 and which first flew in 1966.
Implementation
RTL inverter
A bipolar transistor switch is the simplest RTL gate (inverter or NOT gate) implementing logical negation. It consists of a common-emitter stage with a base resistor connected between the base and the input voltage source. The role of the base resistor is to expand the very small transistor input voltage range (about 0.7 V) to the logical "1" level (about 3.5 V) by converting the input voltage into current. Its resistance is settled by a compromise: it is chosen low enough to saturate the transistor and high enough to obtain high input resistance. The role of the collector resistor is to convert the collector current into voltage; its resistance is chosen high enough to saturate the transistor and low enough to obtain low output resistance (high fan-out).
One-transistor RTL NOR gate
With two or more base resistors (R3 and R4) instead of one, the inverter becomes a two-input RTL NOR gate (see the figure on the right). The logical operation OR is performed by applying consecutively the two arithmetic operations addition and comparison (the input resistor network acts as a parallel voltage summer with equally weighted inputs and the following common-emitter transistor stage as a voltage comparator with a threshold about 0.7 V). The equivalent resistance of all the resistors |
https://en.wikipedia.org/wiki/Diode%E2%80%93transistor%20logic | Diode–transistor logic (DTL) is a class of digital circuits that is the direct ancestor of transistor–transistor logic. It is called so because the logic gating functions AND and OR are performed by diode logic, while logical inversion (NOT) and amplification (providing signal restoration) is performed by a transistor (in contrast with RTL and TTL).
Implementations
The DTL circuit shown in the first picture consists of three stages: an input diode logic stage (D1, D2 and R1), an intermediate level shifting stage (R3 and R4), and an output common-emitter amplifier stage (Q1 and R2). If both inputs A and B are high (logic 1; near V+), then the diodes D1 and D2 are reverse biased. Resistors R1 and R3 will then supply enough current to turn on Q1 (drive Q1 into saturation) and also supply the current needed by R4. There will be a small positive voltage on the base of Q1 (VBE, about 0.3 V for germanium and 0.6 V for silicon). The turned on transistor's collector current will then pull the output Q low (logic 0; VCE(sat), usually less than 1 volt). If either or both inputs are low, then at least one of the input diodes conducts and pulls the voltage at the anodes to a value less than about 2 volts. R3 and R4 then act as a voltage divider that makes Q1's base voltage negative and consequently turns off Q1. Q1's collector current will be essentially zero, so R2 will pull the output voltage Q high (logic 1; near V+).
Early diode logic with transistor inverter
Up until 1952, IBM manufactured transistors by modifying off-the-shelf germanium diodes, after which they had their own alloy-junction transistor manufacturing plant at Poughkeepsie. In the mid 1950s, diode logic was used in the IBM 608 which was the first all-transistorized computer in the world. A single card would hold four two-way circuits or three three-way or one eight-way. All input and output signals were compatible. The circuits were capable of reliably switching pulses as narrow as one microsecond.
|
https://en.wikipedia.org/wiki/Slax | Slax is a LiveCD Linux distribution developed by Tomáš Matějíček and based on upstream customizable Linux distributions. Packages can be added by apt package manager or can be prepared as modules. The tagline for Slax refers to itself as "your pocket operating system".
Features
One of the main benefits of the Slax distribution is its ease of customization. Additional software can be added and removed, using Slax modules. A traditional package manager such as Debian's APT is not required to load additional software; Slax modules are completely self-contained. However, APT is fully supported. Users can also modify the default CD image or USB drive installation to customize the packages available in the distribution on boot. Slax also allows Debian packages to be converted into Slax modules.
Slax modules are compressed read-only SquashFS file system images that are compressed with a LZMA compressor. The various modules are stacked together to build the complete Slax root directory. A supplemental writable layer (a tmpfs file system) is put on the top of the stack to implement the write functionality.
The stackable file system of choice changed between Slax versions 5 (UnionFS) and 6 (aufs), as did the module file name extension (changed from to ).
Versions
Slackware-Live! 1
Slackware-Live! 1.8.0.1 was based on Slackware 8.0. Slackware-Live! 1.81.0.21 was based on Slackware 8.1.
Slackware-Live! 2
Slackware-Live! 2.9.0.1 was based on Slackware 9.0.
Slax 3
Slackware-Live! was renamed to SLAX in 3.0.24.
Slax 4
Slax 4.0.1 is based on 4.0.1 linux live scripts with Linux Kernel 2.4.25.
Slax 4.2.0 special is based on SLAX 4.2.0.
Slax 5
There were five editions of Slax 5:
Slax Standard was the standard edition for normal personal use, introduced in Slax 5.0.0.
Slax KillBill included Wine, DOSBox and QEMU to run DOS and Microsoft Windows applications, introduced with Slax 5.0.2.
Slax Server supplied additional Internet functionality and came with pre-configured DN |
https://en.wikipedia.org/wiki/SystemRescue | SystemRescue (Previously known as "SystemRescueCD") is a Linux distribution for x86 64 and x86 computers. The primary purpose of SystemRescue is to repair unbootable or otherwise damaged computer systems after a system crash. SystemRescue is not intended to be used as a permanent operating system. It runs from a Live CD, a USB flash drive or any type of hard drive. It was designed by a team led by François Dupoux, and is based on Arch Linux since version 6.0. Starting with version 6.0, it has systemd as its init system.
Features
SystemRescue is capable of graphics using the Linux framebuffer option for tools such as GParted. It has options such as connecting to the Internet through an ADSL modem or Ethernet and graphical web browsers such as Mozilla Firefox.
SystemRescue features include:
GNU Parted and GParted to partition disks and resize partitions, including FAT32 and NTFS
fdisk to edit the disk partition table
PartImage - disk imaging software which copies only used sectors
TestDisk - to recover lost partition and PhotoRec to recover lost data
smartmontools - a S.M.A.R.T. suite for HDD health reporting and data loss prevention
ddrescue - to extract recoverable data from physically damaged HDD and listing damaged sectors
FSArchiver - a system tool that allows you to save the contents of a file-system to a compressed archive file
nwipe - a secure data erasure tool (fork of DBAN) for harddrives to remove data remanence, supports Gutmann method plus other overwriting standard algorithms and patterns.
A CD and DVD burner - dvd+rw-tools
Two bootloaders - GRUB and SYSLINUX
Web browsers - Firefox, ELinks
File manager - emelFM2
Archiving and unarchiving abilities
File system tools - file system create, delete, resize, move
Support for many file systems, including full NTFS read/write access (via NTFS-3G) as well as FAT32 and Mac OS HFS
Support for Intel x86 and PowerPC systems, including Macs
Ability to create a boot disk for operating systems
Suppor |
https://en.wikipedia.org/wiki/Digital%20organism | A digital organism is a self-replicating computer program that mutates and evolves. Digital organisms are used as a tool to study the dynamics of Darwinian evolution, and to test or verify specific hypotheses or mathematical models of evolution. The study of digital organisms is closely related to the area of artificial life.
History
Digital organisms can be traced back to the game Darwin, developed in 1961 at Bell Labs, in which computer programs had to compete with each other by trying to stop others from executing . A similar implementation that followed this was the game Core War. In Core War, it turned out that one of the winning strategies was to replicate as fast as possible, which deprived the opponent of all computational resources. Programs in the Core War game were also able to mutate themselves and each other by overwriting instructions in the simulated "memory" in which the game took place. This allowed competing programs to embed damaging instructions in each other that caused errors (terminating the process that read it), "enslaved processes" (making an enemy program work for you), or even change strategies mid-game and heal themselves.
Steen Rasmussen at Los Alamos National Laboratory took the idea from Core War one step further in his core world system by introducing a genetic algorithm that automatically wrote programs. However, Rasmussen did not observe the evolution of complex and stable programs. It turned out that the programming language in which core world programs were written was very brittle, and more often than not mutations would completely destroy the functionality of a program.
The first to solve the issue of program brittleness was Thomas S. Ray with his Tierra system, which was similar to core world. Ray made some key changes to the programming language such that mutations were much less likely to destroy a program. With these modifications, he observed for the first time computer programs that did indeed evolve in a meaningf |
https://en.wikipedia.org/wiki/Evolutionary%20biology | Evolutionary biology is the subfield of biology that studies the evolutionary processes (natural selection, common descent, speciation) that produced the diversity of life on Earth. It is also defined as the study of the history of life forms on Earth. Evolution holds that all species are related and gradually change over generations. In a population, the genetic variations affect the phenotypes (physical characteristics) of an organism. These changes in the phenotypes will be an advantage to some organisms, which will then be passed onto their offspring. Some examples of evolution in species over many generations are the peppered moth and flightless birds. In the 1930s, the discipline of evolutionary biology emerged through what Julian Huxley called the modern synthesis of understanding, from previously unrelated fields of biological research, such as genetics and ecology, systematics, and paleontology.
The investigational range of current research has widened to encompass the genetic architecture of adaptation, molecular evolution, and the different forces that contribute to evolution, such as sexual selection, genetic drift, and biogeography. Moreover, the newer field of evolutionary developmental biology ("evo-devo") investigates how embryogenesis is controlled, thus yielding a wider synthesis that integrates developmental biology with the fields of study covered by the earlier evolutionary synthesis.
Subfields
Evolution is the central unifying concept in biology. Biology can be divided into various ways. One way is by the level of biological organization, from molecular to cell, organism to population. Another way is by perceived taxonomic group, with fields such as zoology, botany, and microbiology, reflecting what was once seen as the major divisions of life. A third way is by approaches, such as field biology, theoretical biology, experimental evolution, and paleontology. These alternative ways of dividing up the subject have been combined with evolution |
https://en.wikipedia.org/wiki/Strain%20gauge | A strain gauge (also spelled strain gage) is a device used to measure strain on an object. Invented by Edward E. Simmons and Arthur C. Ruge in 1938, the most common type of strain gauge consists of an insulating flexible backing which supports a metallic foil pattern. The gauge is attached to the object by a suitable adhesive, such as cyanoacrylate. As the object is deformed, the foil is deformed, causing its electrical resistance to change. This resistance change, usually measured using a Wheatstone bridge, is related to the strain by the quantity known as the gauge factor.
History
Edward E. Simmons and Professor Arthur C. Ruge independently invented the strain gauge.
Simmons was involved in a research project by Dätwyler and Clark at Caltech between 1936 and 1938. They researched the stress-strain behavior of metals under shock loads. Simmon came up with an original way to measure the force introduced into the sample by equipping a dynamometer with fine resistance wires.
Arthur C. Ruge, a professor at MIT, on the other hand, conducted research in seismology. He tried to analyze the behavior of a model water tank installed on a vibration table. He was not able to utilize the standard optical strain measurement methods of his time due to the small scale and low strains in his model. Professor Ruge (and his assistant J. Hanns Meier) had the epiphany of measuring the resistance change in metallic wires caused by strain cemented on the thin walls of the water tank model.
The development of the strain gauge was essentially just a byproduct of other research projects. Edward E. Simmons and Professor Arthur C. Ruge developed a widely used and useful measurement tool due to the lack of an alternative at their times.
Arthur C. Ruge realized the commercial utility of the strain gauge. His employer at MIT waived all claims on the right of the invention, as they did not predict the economic and large-scale usage potential. This prediction turned out to be false. The st |
https://en.wikipedia.org/wiki/Weismann%20barrier | The Weismann barrier, proposed by August Weismann, is the strict distinction between the "immortal" germ cell lineages producing gametes and "disposable" somatic cells in animals (but not plants), in contrast to Charles Darwin's proposed pangenesis mechanism for inheritance. In more precise terminology, hereditary information moves only from germline cells to somatic cells (that is, somatic mutations are not inherited). This does not refer to the central dogma of molecular biology, which states that no sequential information can travel from protein to DNA or RNA, but both hypotheses relate to a gene-centric view of life.
Weismann set out the concept in his 1892 book Das Keimplasma: eine Theorie der Vererbung (The Germ Plasm: a theory of inheritance).
The Weismann barrier was of great importance in its day and among other influences it effectively banished certain Lamarckian concepts: in particular, it would make Lamarckian inheritance from changes to the body (the soma) difficult or impossible. It remains important, but has however required qualification in the light of modern understanding of horizontal gene transfer and some other genetic and histological developments. The use of this theory, commonly in the context of the germ plasm theory of the late 19th century, before the development of better-based and more sophisticated concepts of genetics in the early 20th century, is sometimes referred to as Weismannism. Some authors distinguish Weismannist development (either preformistic or epigenetic) that in which there is a distinct germ line, from somatic embryogenesis. This type of development is correlated with the evolution of death of the somatic line.
Plants and basal animals
In plants, genetic changes in somatic lines can and do result in genetic changes in the germ lines, because the germ cells are produced by somatic cell lineages (vegetative meristems), which may be old enough (many years) to have accumulated multiple mutations since seed germination, |
https://en.wikipedia.org/wiki/Open%20Data-Link%20Interface | The Open Data-Link Interface (ODI), developed by Apple and Novell, serves the same function as Microsoft and 3COM's Network Driver Interface Specification (NDIS). Originally, ODI was written for NetWare and Macintosh environments. Like NDIS, ODI provides rules that establish a vendor-neutral interface between the protocol stack and the adapter driver. It resides in Layer 2, the Data Link layer, of the OSI model. This interface also enables one or more network drivers to support one or more protocol stacks.
See also
Network Driver Interface Specification (NDIS)
Uniform Driver Interface (UDI)
Universal Network Device Interface (UNDI)
PC/TCP Packet Driver
Virtual Loadable Module (VLM)
NetWare I/O Subsystem (NIOS)
Personal NetWare (PNW)
DR-WebSpyder
References
Computer networks |
https://en.wikipedia.org/wiki/XSIL | XSIL (Extensible Scientific Interchange Language) is an XML-based transport language for scientific data, supporting the inclusion of both in-file data and metadata. The language comes with an extensible Java object model. The language's elementary objects include Param (arbitrary association between a keyword and a value), Array, Table (a set of column headings followed by a set of records), and Stream, which enables one to either encapsulate data inside the XSIL file or point to an external data source.
BFD is an XML dialect based on XSIL.
External links
XSIL: Extensible Scientific Interchange Language
XML-based standards
Data modeling languages |
https://en.wikipedia.org/wiki/Binary%20Format%20Description%20language | The Binary Format Description (BFD) language is an extension of XSIL which has added conditionals and the ability to reference files by their stream numbers, rather than by their public URLs. A template written in the BFD language can be applied to a binary data file to produce a file with that data formatted with descriptive XML tags. Such XML-tagged data is then readable by humans and generally by a wider set of computer programs than could read the original data file.
External links
Binary Format Description (BFD) Language
XML-based standards
Data modeling languages |
https://en.wikipedia.org/wiki/Function%20overloading | In some programming languages, function overloading or method overloading is the ability to create multiple functions of the same name with different implementations. Calls to an overloaded function will run a specific implementation of that function appropriate to the context of the call, allowing one function call to perform different tasks depending on context.
For example, and are overloaded functions. To call the latter, an object must be passed as a parameter, whereas the former does not require a parameter, and is called with an empty parameter field. A common error would be to assign a default value to the object in the second function, which would result in an ambiguous call error, as the compiler wouldn't know which of the two methods to use.
Another example is a function that executes different actions based on whether it's printing text or photos. The two different functions may be overloaded as If we write the overloaded print functions for all objects our program will "print", we never have to worry about the type of the object, and the correct function call again, the call is always: .
Languages supporting overloading
Languages which support function overloading include, but are not necessarily limited to, the following:
Apex
C
C++
C#
Clojure
Swift
Fortran
Kotlin
Java
Julia
PostgreSQL and PL/SQL
Scala
TypeScript
Wolfram Language
Elixir
Nim
Crystal
Rules in function overloading
The same function name is used for more than one function definition
The functions must differ either by the arity or types of their parameters
It is a classification of static polymorphism in which a function call is resolved using some "best match" algorithm, where the particular function to call is resolved by finding the best match of the formal parameter types with the actual parameter types. The details of this algorithm vary from language to language.
Function overloading is usually associated with statically-typed programming languages that |
https://en.wikipedia.org/wiki/Final%20Fantasy%20Crystal%20Chronicles%20%28video%20game%29 | is an action role-playing video game developed by The Game Designers Studio and published by Nintendo for the GameCube. It was released in 2003 in Japan and 2004 in North America, Europe and Australia. A remastered version for Nintendo Switch, PlayStation 4, Android, and iOS was released in August 2020. A spin-off of the Final Fantasy series and beginning of the series of the same name, Crystal Chronicles was the first title in the franchise to be released for a Nintendo home console since Final Fantasy VI in 1994.
Players take on the role of adventurers who travel in a caravan gathering mystical fuel for crystals which protect the world's settlements from the destructive Miasma. The single-player campaign has the player escort the vessel carrying the crystal's energy, defending it from enemies and solving puzzles to progress. Multiplayer, which uses Game Boy Advance units connected using the console's link cable, has up to four players protecting the vessel.
Deciding to partner with Nintendo for game development following severe financial problems created by the failure of Final Fantasy: The Spirits Within, franchise creator Square formed the Game Designers Studio as a shell company to develop for Nintendo hardware without impacting games for Sony platforms. The development team wanted to create an accessible gameplay experience focusing on multiplayer. The music, written by Kumi Tanioka, made extensive use of medieval and Renaissance musical instruments.
Upon release, the title was positively received by journalists, and was nominated for multiple awards. Reaching high sales positions in Japan and the West, it went on to sell over one million copies worldwide. The remastered version saw generally mixed reviews, with many faulting the change to online-only multiplayer, and by-then dated gameplay mechanics. Subsequent entries in the Crystal Chronicles series have released for Nintendo consoles, beginning with Ring of Fates for the Nintendo DS.
Gameplay
Final Fa |
https://en.wikipedia.org/wiki/Intrinsic%20parity | In quantum mechanics, the intrinsic parity is a phase factor that arises as an eigenvalue of the parity operation (a reflection about the origin). To see that the parity's eigenvalues are phase factors, we assume an eigenstate of the parity operation (this is realized because the intrinsic parity is a property of a particle species) and use the fact that two parity transformations leave the particle in the same state, thus the new wave function can differ by only a phase factor, i.e.: thus , since these are the only eigenstates satisfying the above equation.
The intrinsic parity's phase is conserved for non-weak interactions (the product of the intrinsic parities is the same before and after the reaction). As the Hamiltonian is invariant under a parity transformation. The intrinsic parity of a system is the product of the intrinsic parities of the particles, for instance for noninteracting particles we have . Since the parity commutes with the Hamiltonian and its eigenvalue does not change with time, therefore the intrinsic parities phase is a conserved quantity.
A consequence of the Dirac equation is that the intrinsic parity of fermions and antifermions obey the relation , so particles and their antiparticles have the opposite parity. Single leptons can never be created or destroyed in experiments, as lepton number is a conserved quantity. This means experiments are unable to distinguish the sign of a leptons parity, so by convention it is chosen that leptons have intrinsic parity +1, antileptons have . Similarly the parity of the quarks is chosen to be +1, and antiquarks is -1.
References
Physical quantities
Quantum field theory
Quantum mechanics |
https://en.wikipedia.org/wiki/Serial%20digital%20interface | Serial digital interface (SDI) is a family of digital video interfaces first standardized by SMPTE (The Society of Motion Picture and Television Engineers) in 1989. For example, ITU-R BT.656 and SMPTE 259M define digital video interfaces used for broadcast-grade video. A related standard, known as high-definition serial digital interface (HD-SDI), is standardized in SMPTE 292M; this provides a nominal data rate of 1.485 Gbit/s.
Additional SDI standards have been introduced to support increasing video resolutions (HD, UHD and beyond), frame rates, stereoscopic (3D) video, and color depth. Dual link HD-SDI consists of a pair of SMPTE 292M links, standardized by SMPTE 372M in 1998; this provides a nominal 2.970 Gbit/s interface used in applications (such as digital cinema or HDTV 1080P) that require greater fidelity and resolution than standard HDTV can provide. 3G-SDI (standardized in SMPTE 424M) consists of a single 2.970 Gbit/s serial link that allows replacing dual link HD-SDI. 6G-SDI and 12G-SDI standards were published on March 19, 2015.
These standards are used for transmission of uncompressed, unencrypted digital video signals (optionally including embedded audio and time code) within television facilities; they can also be used for packetized data. SDI is used to connect together different pieces of equipment such as recorders, monitors, PCs and vision mixers. Coaxial variants of the specification range in length but are typically less than . Fiber optic variants of the specification such as 297M allow for long-distance transmission limited only by maximum fiber length or repeaters. SDI and HD-SDI are usually available only in professional video equipment because various licensing agreements restrict the use of unencrypted digital interfaces, such as SDI, prohibiting their use in consumer equipment. Several professional video and HD-video capable DSLR cameras and all uncompressed video capable consumer cameras use the HDMI interface, often called clean HDMI |
https://en.wikipedia.org/wiki/Gnutella2 | Gnutella2, often referred to as G2, is a peer-to-peer protocol developed mainly by Michael Stokes and released in 2002.
While inspired by the gnutella protocol, G2 shares little of its design with the exception of its connection handshake and download mechanics.
G2 adopts an extensible binary packet format and an entirely new search algorithm.
Furthermore, G2 has a related (but significantly different) network topology and an improved metadata system, which helps effectively to reduce fake files, such as viruses, on the network.
History
In November 2002, Michael Stokes announced the Gnutella2 protocol to the Gnutella Developers Forum. While some thought the goals stated for Gnutella2 are primarily to make a clean break with the gnutella 0.6 protocol and start over, so that some of gnutella's less clean parts would be done more elegantly and, in general, be impressive and desirable; other developers, primarily those of LimeWire and BearShare, thought it to be a "cheap publicity stunt" and discounted technical merits. Some still refuse to refer to the network as "Gnutella2", and instead, refer to it as "Mike's Protocol" ("MP").
The Gnutella2 protocol still uses the old "GNUTELLA CONNECT/0.6" handshake string for its connections as defined in the gnutella 0.6 specifications. This backwardly compatible handshake method was criticized by the Gnutella Developers Forum as an attempt to use the gnutella network for bootstrapping the new, unrelated network, while proponents of the network claimed that its intent was to remain backwards-compatible with gnutella and to allow current gnutella clients to add Gnutella2 at their leisure.
With the developers entrenched in their positions, a flame war soon erupted, further cementing both sides' resolve.
The draft specifications were released on March 26, 2003, and more detailed specifications soon followed. G2 is not supported by many of the "old" gnutella network clients, however, many Gnutella2 clients still also connect |
https://en.wikipedia.org/wiki/Organ%20system | An organ system is a biological system consisting of a group of organs that work together to perform one or more functions. Each organ has a specialized role in a plant or animal body, and is made up of distinct tissues.
Animals
Other animals have similar organ systems to humans although simpler animals may have fewer organs in an organ system or even fewer organ systems.
Humans
There are 11 distinct organ systems in human beings, which form the basis of human anatomy and physiology. The 11 organ systems: the respiratory system, digestive and excretory system, circulatory system, urinary system, integumentary system, skeletal system, muscular system, endocrine system, lymphatic system, nervous system, and reproductive system. There are other systems in the body that are not organ systems—for example, the immune system protects the organism from infection, but it is not an organ system since it is not composed of organs. Some organs are in more than one system—for example, the nose is in the respiratory system and also serves as a sensory organ in the nervous system; the testes and ovaries are both part of the reproductive and endocrine systems.
Plants
Plants have two major organs systems. Vascular plants have two distinct organ systems: a shoot system, and a root system. The shoot system consists stems, leaves, and the reproductive parts of the plant (flowers and fruits). The shoot system generally grows above ground, where it absorbs the light needed for photosynthesis. The root system, which supports the plants and absorbs water and minerals, is usually underground.
See also
List of systems of the human body
References
Organ systems |
https://en.wikipedia.org/wiki/RTLinux | RTLinux is a hard realtime real-time operating system (RTOS) microkernel that runs the entire Linux operating system as a fully preemptive process. The hard real-time property makes it possible to control robots, data acquisition systems, manufacturing plants, and other time-sensitive instruments and machines from RTLinux applications. The design was patented. Despite the similar name, it is not related to the Real-Time Linux project of the Linux Foundation.
RTLinux was developed by Victor Yodaiken, Michael Barabanov, Cort Dougan and others at the New Mexico Institute of Mining and Technology and then as a commercial product at FSMLabs. Wind River Systems acquired FSMLabs embedded technology in February 2007 and made a version available as Wind River Real-Time Core for Wind River Linux. As of August 2011, Wind River has discontinued the Wind River Real-Time Core product line, effectively ending commercial support for the RTLinux product.
Background
The key RTLinux design objective was to add hard real-time capabilities to a commodity operating system to facilitate the development of complex control programs with both capabilities. For example, one might want to develop a real-time motor controller that used a commodity database and exported a web operator interface. Instead of attempting to build a single operating system that could support real-time and non-real-time capabilities, RTLinux was designed to share a computing device between a real-time and non-real-time operating system so that (1) the real-time operating system could never be blocked from execution by the non-real-time operating system and (2) components running in the two different environments could easily share data. As the name implies RTLinux was originally designed to use Linux as the non-real-time system but it eventually evolved so that the RTCore real-time kernel could run with either Linux or Berkeley Software Distribution (BSD) Unix.
Multi-Environment Real-Time (MERT) was the first exam |
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