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Due to the large number of bits needed to encode the three registers of a 3-operand instruction, RISC architectures that have 16-bit instructions are invariably 2-operand designs, such as the Atmel AVR, TI MSP430, and some versions of ARM Thumb. RISC architectures that have 32-bit instructions are usually 3-operand des... | Instruction set architecture | Wikipedia | 429 | 47772 | https://en.wikipedia.org/wiki/Instruction%20set%20architecture | Technology | Computer architecture concepts | null | vital_articles |
Instruction length
The size or length of an instruction varies widely, from as little as four bits in some microcontrollers to many hundreds of bits in some VLIW systems. Processors used in personal computers, mainframes, and supercomputers have minimum instruction sizes between 8 and 64 bits. The longest possible inst... | Instruction set architecture | Wikipedia | 383 | 47772 | https://en.wikipedia.org/wiki/Instruction%20set%20architecture | Technology | Computer architecture concepts | null | vital_articles |
Computers with high code density often have complex instructions for procedure entry, parameterized returns, loops, etc. (therefore retroactively named Complex Instruction Set Computers, CISC). However, more typical, or frequent, "CISC" instructions merely combine a basic ALU operation, such as "add", with the access o... | Instruction set architecture | Wikipedia | 472 | 47772 | https://en.wikipedia.org/wiki/Instruction%20set%20architecture | Technology | Computer architecture concepts | null | vital_articles |
In practice, code density is also dependent on the compiler. Most optimizing compilers have options that control whether to optimize code generation for execution speed or for code density. For instance GCC has the option -Os to optimize for small machine code size, and -O3 to optimize for execution speed at the cost o... | Instruction set architecture | Wikipedia | 461 | 47772 | https://en.wikipedia.org/wiki/Instruction%20set%20architecture | Technology | Computer architecture concepts | null | vital_articles |
A given instruction set can be implemented in a variety of ways. All ways of implementing a particular instruction set provide the same programming model, and all implementations of that instruction set are able to run the same executables. The various ways of implementing an instruction set give different tradeoffs be... | Instruction set architecture | Wikipedia | 459 | 47772 | https://en.wikipedia.org/wiki/Instruction%20set%20architecture | Technology | Computer architecture concepts | null | vital_articles |
The demands of high-speed digital signal processing have pushed in the opposite direction—forcing instructions to be implemented in a particular way. For example, to perform digital filters fast enough, the MAC instruction in a typical digital signal processor (DSP) must use a kind of Harvard architecture that can fetc... | Instruction set architecture | Wikipedia | 82 | 47772 | https://en.wikipedia.org/wiki/Instruction%20set%20architecture | Technology | Computer architecture concepts | null | vital_articles |
Quality of life (QOL) is defined by the World Health Organization as "an individual's perception of their position in life in the context of the culture and value systems in which they live and in relation to their goals, expectations, standards and concerns".
Standard indicators of the quality of life include wealth... | Quality of life | Wikipedia | 489 | 47789 | https://en.wikipedia.org/wiki/Quality%20of%20life | Biology and health sciences | Health and fitness: General | Health | vital_articles |
There are many different methods of measuring quality of life in terms of health care, wealth, and materialistic goods. However, it is much more difficult to measure meaningful expression of one's desires. One way to do so is to evaluate the scope of how individuals have fulfilled their own ideals. Quality of life can ... | Quality of life | Wikipedia | 491 | 47789 | https://en.wikipedia.org/wiki/Quality%20of%20life | Biology and health sciences | Health and fitness: General | Health | vital_articles |
Other measures
The Physical Quality of Life Index (PQLI) is a measure developed by sociologist M. D. Morris in the 1970s, based on basic literacy, infant mortality, and life expectancy. Although not as complex as other measures, and now essentially replaced by the Human Development Index, the PQLI is notable for Morris... | Quality of life | Wikipedia | 501 | 47789 | https://en.wikipedia.org/wiki/Quality%20of%20life | Biology and health sciences | Health and fitness: General | Health | vital_articles |
The Social Progress Index measures the extent to which countries provide for the social and environmental needs of their citizens. Fifty-two indicators in the areas of basic human needs, foundations of wellbeing, and opportunity show the relative performance of nations. The index uses outcome measures when there is suf... | Quality of life | Wikipedia | 392 | 47789 | https://en.wikipedia.org/wiki/Quality%20of%20life | Biology and health sciences | Health and fitness: General | Health | vital_articles |
Crimes
Some crimes against property (e.g., graffiti and vandalism) and some "victimless crimes" have been referred to as "quality-of-life crimes". American sociologist James Q. Wilson encapsulated this argument as the broken windows theory, which asserts that relatively minor problems left unattended (such as litter, g... | Quality of life | Wikipedia | 489 | 47789 | https://en.wikipedia.org/wiki/Quality%20of%20life | Biology and health sciences | Health and fitness: General | Health | vital_articles |
In international development
Quality of life has been deemed an important concept in the field of international development because it allows development to be analyzed on a measure that is generally accepted as more comprehensive than standard of living. Within development theory, however, there are varying ideas conc... | Quality of life | Wikipedia | 376 | 47789 | https://en.wikipedia.org/wiki/Quality%20of%20life | Biology and health sciences | Health and fitness: General | Health | vital_articles |
The Voyager program is an American scientific program that employs two interstellar probes, Voyager 1 and Voyager 2. They were launched in 1977 to take advantage of a favorable planetary alignment to explore the two gas giants Jupiter and Saturn and potentially also the ice giants, Uranus and Neptune - to fly near them... | Voyager program | Wikipedia | 425 | 47795 | https://en.wikipedia.org/wiki/Voyager%20program | Technology | Programs and launch sites | null | vital_articles |
The two Voyager space probes were originally conceived as part of the Planetary Grand Tour planned during the late 1960s and early 70s that aimed to explore Jupiter, Saturn, Saturn's moon, Titan, Uranus, Neptune, and Pluto. The mission originated from the Grand Tour program, conceptualized by Gary Flandro, an aerospac... | Voyager program | Wikipedia | 403 | 47795 | https://en.wikipedia.org/wiki/Voyager%20program | Technology | Programs and launch sites | null | vital_articles |
Two mission trajectories were established: JST aimed at Jupiter, Saturn, and enhancing a Titan flyby, while JSX served as a contingency plan. JST focused on a Titan flyby, while JSX provided a flexible mission plan. If JST succeeded, JSX could proceed with the Grand Tour, but in case of failure, JSX could be redirected... | Voyager program | Wikipedia | 485 | 47795 | https://en.wikipedia.org/wiki/Voyager%20program | Technology | Programs and launch sites | null | vital_articles |
During the 1990s, Voyager 1 overtook the slower deep-space probes Pioneer 10 and Pioneer 11 to become the most distant human-made object from Earth, a record that it will keep for the foreseeable future. The New Horizons probe, which had a higher launch velocity than Voyager 1, is travelling more slowly due to the extr... | Voyager program | Wikipedia | 466 | 47795 | https://en.wikipedia.org/wiki/Voyager%20program | Technology | Programs and launch sites | null | vital_articles |
The Voyager spacecraft each weighed at launch, but after fuel usage are now about . Of this weight, each spacecraft carries of scientific instruments. The identical Voyager spacecraft use three-axis-stabilized guidance systems that use gyroscopic and accelerometer inputs to their attitude control computers to point ... | Voyager program | Wikipedia | 508 | 47795 | https://en.wikipedia.org/wiki/Voyager%20program | Technology | Programs and launch sites | null | vital_articles |
Three spacecraft were built, Voyager 1 (VGR 77-1), Voyager 2 (VGR 77-3), and test spare model (VGR 77-2).
Scientific instruments
Computers and data processing
There are three different computer types on the Voyager spacecraft, two of each kind, sometimes used for redundancy. They are proprietary, custom-built comput... | Voyager program | Wikipedia | 472 | 47795 | https://en.wikipedia.org/wiki/Voyager%20program | Technology | Programs and launch sites | null | vital_articles |
The Attitude and Articulation Control Subsystem (AACS) controls the spacecraft orientation (its attitude). It keeps the high-gain antenna pointing towards the Earth, controls attitude changes, and points the scan platform. The custom-built AACS systems on both craft are identical.
It has been erroneously reported on t... | Voyager program | Wikipedia | 445 | 47795 | https://en.wikipedia.org/wiki/Voyager%20program | Technology | Programs and launch sites | null | vital_articles |
Then between 1986 and 1989, new techniques were brought into play to combine the signals from multiple antennas on the ground into one, more powerful signal, in a kind of an antenna array. This was done at Goldstone, California, Canberra (Australia), and Madrid (Spain) using the additional dish antennas available there... | Voyager program | Wikipedia | 423 | 47795 | https://en.wikipedia.org/wiki/Voyager%20program | Technology | Programs and launch sites | null | vital_articles |
The Voyager primary mission was completed in 1989, with the close flyby of Neptune by Voyager 2. The Voyager Interstellar Mission (VIM) is a mission extension, which began when the two spacecraft had already been in flight for over 12 years. The Heliophysics Division of the NASA Science Mission Directorate conducted a ... | Voyager program | Wikipedia | 471 | 47795 | https://en.wikipedia.org/wiki/Voyager%20program | Technology | Programs and launch sites | null | vital_articles |
By the start of VIM, Voyager 1 was at a distance of 40 AU from the Earth, while Voyager 2 was at 31 AU. VIM is in three phases: termination shock, heliosheath exploration, and interstellar exploration phase. The spacecraft began VIM in an environment controlled by the Sun's magnetic field, with the plasma particles bei... | Voyager program | Wikipedia | 491 | 47795 | https://en.wikipedia.org/wiki/Voyager%20program | Technology | Programs and launch sites | null | vital_articles |
In October 2020, astronomers reported a significant unexpected increase in density in the space beyond the Solar System, as detected by the Voyager space probes. According to the researchers, this implies that "the density gradient is a large-scale feature of the VLISM (very local interstellar medium) in the general di... | Voyager program | Wikipedia | 291 | 47795 | https://en.wikipedia.org/wiki/Voyager%20program | Technology | Programs and launch sites | null | vital_articles |
The trogons and quetzals are birds in the order Trogoniformes which contains only one family, the Trogonidae. The family Trogonidae contains 46 species in seven genera. The fossil record of the trogons dates back 49 million years to the Early Eocene. They might constitute a member of the basal radiation of the order C... | Trogon | Wikipedia | 425 | 47798 | https://en.wikipedia.org/wiki/Trogon | Biology and health sciences | Trogoniformes | null | vital_articles |
The earliest formally described fossil specimen is a cranium from the Fur Formation Lower Eocene in Denmark (54 mya). Other trogoniform fossils have been found in the Messel pit deposits from the mid-Eocene in Germany (49 mya), and in Oligocene and Miocene deposits from Switzerland and France respectively. The oldest N... | Trogon | Wikipedia | 473 | 47798 | https://en.wikipedia.org/wiki/Trogon | Biology and health sciences | Trogoniformes | null | vital_articles |
The majority of trogons are birds of tropical and subtropical forests. They have a cosmopolitan distribution in the worlds wet tropics, being found in the Americas, Africa and Asia. A few species are distributed into the temperate zone, with one species, the elegant trogon, reaching the south of the United States, spec... | Trogon | Wikipedia | 431 | 47798 | https://en.wikipedia.org/wiki/Trogon | Biology and health sciences | Trogoniformes | null | vital_articles |
The trogons as a family are fairly uniform in appearance, having compact bodies and long tails (very long in the case of the quetzals), and short necks. Trogons range in size from the , scarlet-rumped trogon to the , resplendent quetzal (not including the male quetzal's tail streamers). Their legs and feet are weak ... | Trogon | Wikipedia | 482 | 47798 | https://en.wikipedia.org/wiki/Trogon | Biology and health sciences | Trogoniformes | null | vital_articles |
Calls
The calls of trogons are generally loud and uncomplex, consisting of monosyllabic hoots and whistles delivered in varying patterns and sequences. The calls of the quetzals and the two Caribbean genera are the most complex. Among the Asian genera the Sumatran trogon (Apalharpactes) has the most atypical call of an... | Trogon | Wikipedia | 459 | 47798 | https://en.wikipedia.org/wiki/Trogon | Biology and health sciences | Trogoniformes | null | vital_articles |
Prey is almost always obtained on the wing. The most commonly employed foraging technique is a sally-glean flight, where a trogon flies from an observation perch to a target on another branch or in foliage. Once there the birds hovers or stalls and snatches the item before returning to its perch to consume the item. Th... | Trogon | Wikipedia | 455 | 47798 | https://en.wikipedia.org/wiki/Trogon | Biology and health sciences | Trogoniformes | null | vital_articles |
The nests of trogons are thought to usually be unlined. Between two and four eggs are laid in a nesting attempt. These are round and generally glossy white or lightly coloured (buff, grey, blue or green), although they get increasingly dirty during incubation. Both parents incubate the eggs (except in the case of the b... | Trogon | Wikipedia | 360 | 47798 | https://en.wikipedia.org/wiki/Trogon | Biology and health sciences | Trogoniformes | null | vital_articles |
Huntington's disease (HD), also known as Huntington's chorea, is an incurable neurodegenerative disease that is mostly inherited. The earliest symptoms are often subtle problems with mood or mental/psychiatric abilities. A general lack of coordination and an unsteady gait often follow. It is also a basal ganglia diseas... | Huntington's disease | Wikipedia | 432 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
No cure for HD is known, and full-time care is required in the later stages. Treatments can relieve some symptoms and in some, improve quality of life. The best evidence for treatment of the movement problems is with tetrabenazine. HD affects about 4 to 15 in 100,000 people of European descent. It is rare among the Fin... | Huntington's disease | Wikipedia | 455 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
The most characteristic initial physical symptoms are jerky, random, and uncontrollable movements called chorea. Many people are not aware of their involuntary movements, or impeded by them. Chorea may be initially exhibited as general restlessness, small unintentionally initiated or uncompleted motions, lack of coordi... | Huntington's disease | Wikipedia | 462 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
Reported neuropsychiatric signs are anxiety, depression, a reduced display of emotions, egocentrism, aggression, and compulsive behavior and hallucination and delusion. Other common psychiatric disorders could include obsessive–compulsive disorder, mania, insomnia and bipolar disorder. Difficulties in recognizing other... | Huntington's disease | Wikipedia | 455 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
HD is one of several trinucleotide repeat disorders that are caused by the length of a repeated section of a gene exceeding a normal range. The HTT gene is located on the short arm of chromosome 4 at 4p16.3. HTT contains a sequence of three DNA bases—cytosine-adenine-guanine (CAG)—repeated multiple times (i.e. ... CAGC... | Huntington's disease | Wikipedia | 432 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
Huntington's disease has autosomal dominant inheritance, meaning that an affected individual typically inherits one copy of the gene with an expanded trinucleotide repeat (the mutant allele) from an affected parent. Since the penetrance of the mutation is very high, those who have a mutated copy of the gene will have t... | Huntington's disease | Wikipedia | 445 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
Mechanisms
Huntingtin protein interacts with over 100 other proteins, and appears to have multiple functions. The behavior of the mutated protein (mHtt) is not completely understood, but it is toxic to certain cell types, particularly brain cells. Early damage is most evident in the subcortical basal ganglia, initially... | Huntington's disease | Wikipedia | 473 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
The toxic action of mHtt may manifest and produce the HD pathology through multiple cellular changes. In its mutant (polyglutamine expanded) form, the protein is more prone to cleavage that creates shorter fragments containing the polyglutamine expansion. These protein fragments have a propensity to undergo misfolding... | Huntington's disease | Wikipedia | 411 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
Initially, damage to the brain is regionally specific with the dorsal striatum in the subcortical basal ganglia being primarily affected, followed later by cortical involvement in all areas. Other areas of the basal ganglia affected include the substantia nigra; cortical involvement includes cortical layers 3, 5, and 6... | Huntington's disease | Wikipedia | 419 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
CREB-binding protein (CBP), a transcriptional coregulator, is essential for cell function because as a coactivator at a significant number of promoters, it activates the transcription of genes for survival pathways. CBP contains an acetyltransferase domain to which HTT binds through its polyglutamine-containing domain.... | Huntington's disease | Wikipedia | 294 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
A physical examination, sometimes combined with a psychological examination, can determine whether the onset of the disease has begun. Excessive unintentional movements of any part of the body are often the reason for seeking medical consultation. If these are abrupt and have random timing and distribution, they sugg... | Huntington's disease | Wikipedia | 245 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
Because HD follows an autosomal dominant pattern of inheritance, a strong motivation exists for individuals who are at risk of inheriting it to seek a diagnosis. The genetic test for HD consists of a blood test, which counts the numbers of CAG repeats in each of the HTT alleles. Cutoffs are given as follows:
At 40 or ... | Huntington's disease | Wikipedia | 320 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
Testing before the onset of symptoms is a life-changing event and a very personal decision. The main reason given for choosing to test for HD is to aid in career and family decisions. Predictive testing for Huntington's disease has been available via linkage analysis (which requires testing multiple family members) sin... | Huntington's disease | Wikipedia | 468 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
Embryos produced using in vitro fertilization may be genetically tested for HD using preimplantation genetic diagnosis. This technique, where one or two cells are extracted from a typically 4- to 8-cell embryo and then tested for the genetic abnormality, can then be used to ensure embryos affected with HD genes are not... | Huntington's disease | Wikipedia | 439 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
About 99% of HD diagnoses based on the typical symptoms and a family history of the disease are confirmed by genetic testing to have the expanded trinucleotide repeat that causes HD. Most of the remaining are called HD-like (HDL) syndromes. The cause of most HDL diseases is unknown, but those with known causes are due ... | Huntington's disease | Wikipedia | 479 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
People with Huntington's disease may see a physical therapist for noninvasive and nonmedication-based ways of managing the physical symptoms. Physical therapists may implement fall risk assessment and prevention, as well as strengthening, stretching, and cardiovascular exercises. Walking aids may be prescribed as appro... | Huntington's disease | Wikipedia | 442 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
Psychiatric symptoms can be treated with medications similar to those used in the general population. Selective serotonin reuptake inhibitors and mirtazapine have been recommended for depression, while atypical antipsychotics are recommended for psychosis and behavioral problems. Specialist neuropsychiatric input is re... | Huntington's disease | Wikipedia | 396 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
Life expectancy in HD is generally around 10 to 30 years following the onset of visible symptoms. Juvenile Huntington's disease has a life expectancy rate of 10 years after onset of visible symptoms. Most life-threatening complications result from muscle coordination, and to a lesser extent, behavioral changes induced ... | Huntington's disease | Wikipedia | 250 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
The late onset of Huntington's disease means it does not usually affect reproduction. The worldwide prevalence of HD is 5–10 cases per 100,000 persons, but varies greatly geographically as a result of ethnicity, local migration and past immigration patterns. Prevalence is similar for men and women. The rate of occurren... | Huntington's disease | Wikipedia | 467 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
The first definite mention of HD was in a letter by Charles Oscar Waters (1816–1892), published in the first edition of Robley Dunglison's Practice of Medicine in 1842. Waters described "a form of chorea, vulgarly called magrums", including accurate descriptions of the chorea, its progression, and the strong heredity o... | Huntington's disease | Wikipedia | 421 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
During the rediscovery of Mendelian inheritance at the turn of the 20th century, HD was used tentatively as an example of autosomal dominant inheritance. English biologist William Bateson used the pedigrees of affected families to establish that HD had an autosomal dominant inheritance pattern. The strong inheritance ... | Huntington's disease | Wikipedia | 435 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
The foundation was involved in the recruitment of more than 100 scientists in the US-Venezuela Huntington's Disease Collaborative Project, which over a 10-year period from 1979, worked to locate the genetic cause. This was achieved in 1983 when a causal gene was approximately located, and in 1993, the gene was precisel... | Huntington's disease | Wikipedia | 460 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
Genetic testing for Huntington's disease has raised several ethical issues. The issues for genetic testing include defining how mature an individual should be before being considered eligible for testing, ensuring the confidentiality of results, and whether companies should be allowed to use test results for decisions ... | Huntington's disease | Wikipedia | 487 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
In 1968, after experiencing HD in his wife's family, Dr. Milton Wexler was inspired to start the Hereditary Disease Foundation (HDF), with the aim of curing genetic illnesses by coordinating and supporting research. The foundation and Wexler's daughter, Nancy Wexler, were key parts of the research team in Venezuela whi... | Huntington's disease | Wikipedia | 412 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
Research is being conducted using many approaches to either prevent Huntington's disease or slow its progression. Disease-modifying strategies can be broadly grouped into three categories: reducing the level of the mutant huntingtin protein (including gene splicing and gene silencing); approaches aimed at improving neu... | Huntington's disease | Wikipedia | 240 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
Gene silencing aims to reduce the production of the mutant protein, since HD is caused by a single dominant gene encoding a toxic protein. Gene silencing experiments in mouse models have shown that when the expression of mHtt is reduced, symptoms improve. The safety of RNA interference, and allele-specific oligonucleot... | Huntington's disease | Wikipedia | 402 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
Increasing huntingtin clearance
Another strategy to reduce the level of mutant huntingtin is to increase the rate at which cells are able to clear it. As mHtt (and many other protein aggregates) are degraded by autophagy, increasing the rate of autophagy has the potential to reduce levels of mHtt and thereby ameliorate... | Huntington's disease | Wikipedia | 414 | 47878 | https://en.wikipedia.org/wiki/Huntington%27s%20disease | Biology and health sciences | Specific diseases | Health | vital_articles |
In probability theory and related fields, a stochastic () or random process is a mathematical object usually defined as a family of random variables in a probability space, where the index of the family often has the interpretation of time. Stochastic processes are widely used as mathematical models of systems and phen... | Stochastic process | Wikipedia | 429 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
Based on their mathematical properties, stochastic processes can be grouped into various categories, which include random walks, martingales, Markov processes, Lévy processes, Gaussian processes, random fields, renewal processes, and branching processes. The study of stochastic processes uses mathematical knowledge and... | Stochastic process | Wikipedia | 374 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
When interpreted as time, if the index set of a stochastic process has a finite or countable number of elements, such as a finite set of numbers, the set of integers, or the natural numbers, then the stochastic process is said to be in discrete time. If the index set is some interval of the real line, then time is said... | Stochastic process | Wikipedia | 487 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
According to the Oxford English Dictionary, early occurrences of the word random in English with its current meaning, which relates to chance or luck, date back to the 16th century, while earlier recorded usages started in the 14th century as a noun meaning "impetuosity, great speed, force, or violence (in riding, runn... | Stochastic process | Wikipedia | 428 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
One of the simplest stochastic processes is the Bernoulli process, which is a sequence of independent and identically distributed (iid) random variables, where each random variable takes either the value one or zero, say one with probability and zero with probability . This process can be linked to an idealisation of ... | Stochastic process | Wikipedia | 451 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
Playing a central role in the theory of probability, the Wiener process is often considered the most important and studied stochastic process, with connections to other stochastic processes. Its index set and state space are the non-negative numbers and real numbers, respectively, so it has both continuous index set an... | Stochastic process | Wikipedia | 473 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
If a Poisson process is defined with a single positive constant, then the process is called a homogeneous Poisson process. The homogeneous Poisson process is a member of important classes of stochastic processes such as Markov processes and Lévy processes.
The homogeneous Poisson process can be defined and generalized... | Stochastic process | Wikipedia | 485 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
There are other ways to consider a stochastic process, with the above definition being considered the traditional one. For example, a stochastic process can be interpreted or defined as a -valued random variable, where is the space of all the possible functions from the set into the space . However this alternative d... | Stochastic process | Wikipedia | 388 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
Increment
An increment of a stochastic process is the difference between two random variables of the same stochastic process. For a stochastic process with an index set that can be interpreted as time, an increment is how much the stochastic process changes over a certain time period. For example, if is a stochastic p... | Stochastic process | Wikipedia | 461 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
all have the same probability distribution. The index set of a stationary stochastic process is usually interpreted as time, so it can be the integers or the real line. But the concept of stationarity also exists for point processes and random fields, where the index set is not interpreted as time.
When the index set ... | Stochastic process | Wikipedia | 462 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
Modification
A modification of a stochastic process is another stochastic process, which is closely related to the original stochastic process. More precisely, a stochastic process that has the same index set , state space , and probability space as another stochastic process is said to be a modification of if for ... | Stochastic process | Wikipedia | 424 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
More precisely, a real-valued continuous-time stochastic process with a probability space is separable if its index set has a dense countable subset and there is a set of probability zero, so , such that for every open set and every closed set , the two events and differ from each other at most on a subset of .... | Stochastic process | Wikipedia | 385 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
A Skorokhod space, also written as Skorohod space, is a mathematical space of all the functions that are right-continuous with left limits, defined on some interval of the real line such as or , and take values on the real line or on some metric space. Such functions are known as càdlàg or cadlag functions, based on t... | Stochastic process | Wikipedia | 497 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
A Markov chain is a type of Markov process that has either discrete state space or discrete index set (often representing time), but the precise definition of a Markov chain varies. For example, it is common to define a Markov chain as a Markov process in either discrete or continuous time with a countable state space ... | Stochastic process | Wikipedia | 495 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
Martingales can also be created from stochastic processes by applying some suitable transformations, which is the case for the homogeneous Poisson process (on the real line) resulting in a martingale called the compensated Poisson process. Martingales can also be built from other martingales. For example, there are mar... | Stochastic process | Wikipedia | 489 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
A random field is a collection of random variables indexed by a -dimensional Euclidean space or some manifold. In general, a random field can be considered an example of a stochastic or random process, where the index set is not necessarily a subset of the real line. But there is a convention that an indexed collection... | Stochastic process | Wikipedia | 443 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
After Cardano, Jakob Bernoulli wrote Ars Conjectandi, which is considered a significant event in the history of probability theory. Bernoulli's book was published, also posthumously, in 1713 and inspired many mathematicians to study probability. But despite some renowned mathematicians contributing to probability theor... | Stochastic process | Wikipedia | 511 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
Birth of modern probability theory
In 1933, Andrei Kolmogorov published in German, his book on the foundations of probability theory titled Grundbegriffe der Wahrscheinlichkeitsrechnung, where Kolmogorov used measure theory to develop an axiomatic framework for probability theory. The publication of this book is now wi... | Stochastic process | Wikipedia | 418 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
In 1953, Doob published his book Stochastic processes, which had a strong influence on the theory of stochastic processes and stressed the importance of measure theory in probability.
Doob also chiefly developed the theory of martingales, with later substantial contributions by Paul-André Meyer. Earlier work had been ... | Stochastic process | Wikipedia | 410 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
Bernoulli process
The Bernoulli process, which can serve as a mathematical model for flipping a biased coin, is possibly the first stochastic process to have been studied. The process is a sequence of independent Bernoulli trials, which are named after Jacob Bernoulli who used them to study games of chance, including p... | Stochastic process | Wikipedia | 457 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
The French mathematician Louis Bachelier used a Wiener process in his 1900 thesis in order to model price changes on the Paris Bourse, a stock exchange, without knowing the work of Thiele. It has been speculated that Bachelier drew ideas from the random walk model of Jules Regnault, but Bachelier did not cite him, and ... | Stochastic process | Wikipedia | 481 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
Another discovery occurred in Denmark in 1909 when A.K. Erlang derived the Poisson distribution when developing a mathematical model for the number of incoming phone calls in a finite time interval. Erlang was not at the time aware of Poisson's earlier work and assumed that the number phone calls arriving in each inter... | Stochastic process | Wikipedia | 479 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
Andrei Kolmogorov developed in a 1931 paper a large part of the early theory of continuous-time Markov processes. Kolmogorov was partly inspired by Louis Bachelier's 1900 work on fluctuations in the stock market as well as Norbert Wiener's work on Einstein's model of Brownian movement. He introduced and studied a parti... | Stochastic process | Wikipedia | 507 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
Construction issues
When constructing continuous-time stochastic processes certain mathematical difficulties arise, due to the uncountable index sets, which do not occur with discrete-time processes. One problem is that it is possible to have more than one stochastic process with the same finite-dimensional distributio... | Stochastic process | Wikipedia | 442 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
Another approach is possible, originally developed by Anatoliy Skorokhod and Andrei Kolmogorov, for a continuous-time stochastic process with any metric space as its state space. For the construction of such a stochastic process, it is assumed that the sample functions of the stochastic process belong to some suitable ... | Stochastic process | Wikipedia | 407 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
Stochastic Volatility Models
Another significant application of stochastic processes in finance is in stochastic volatility models, which aim to capture the time-varying nature of market volatility. The Heston model is a popular example, allowing for the volatility of asset prices to follow its own stochastic process.... | Stochastic process | Wikipedia | 418 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
Queuing Theory
Another significant application of stochastic processes in computer science is in queuing theory, which models the random arrival and service of tasks in a system. This is particularly relevant in network traffic analysis and server management. For instance, queuing models help predict delays, manage re... | Stochastic process | Wikipedia | 112 | 47895 | https://en.wikipedia.org/wiki/Stochastic%20process | Mathematics | Statistics and probability | null | vital_articles |
In set theory, the union (denoted by ∪) of a collection of sets is the set of all elements in the collection. It is one of the fundamental operations through which sets can be combined and related to each other.
A refers to a union of zero () sets and it is by definition equal to the empty set.
For explanation of t... | Union (set theory) | Wikipedia | 461 | 47949 | https://en.wikipedia.org/wiki/Union%20%28set%20theory%29 | Mathematics | Discrete mathematics | null | vital_articles |
Finite unions
One can take the union of several sets simultaneously. For example, the union of three sets A, B, and C contains all elements of A, all elements of B, and all elements of C, and nothing else. Thus, x is an element of A ∪ B ∪ C if and only if x is in at least one of A, B, and C.
A finite union is the un... | Union (set theory) | Wikipedia | 368 | 47949 | https://en.wikipedia.org/wiki/Union%20%28set%20theory%29 | Mathematics | Discrete mathematics | null | vital_articles |
Authentication (from authentikos, "real, genuine", from αὐθέντης authentes, "author") is the act of proving an assertion, such as the identity of a computer system user. In contrast with identification, the act of indicating a person or thing's identity, authentication is the process of verifying that identity. It mig... | Authentication | Wikipedia | 374 | 47967 | https://en.wikipedia.org/wiki/Authentication | Technology | Cryptography | null | vital_articles |
The second type of authentication is comparing the attributes of the object itself to what is known about objects of that origin. For example, an art expert might look for similarities in the style of painting, check the location and form of a signature, or compare the object to an old photograph. An archaeologist, on ... | Authentication | Wikipedia | 505 | 47967 | https://en.wikipedia.org/wiki/Authentication | Technology | Cryptography | null | vital_articles |
In computer science, a user can be given access to secure systems based on user credentials that imply authenticity. A network administrator can give a user a password, or provide the user with a key card or other access devices to allow system access. In this case, authenticity is implied but not guaranteed.
Consumer... | Authentication | Wikipedia | 510 | 47967 | https://en.wikipedia.org/wiki/Authentication | Technology | Cryptography | null | vital_articles |
Single-factor authentication
As the weakest level of authentication, only a single component from one of the three categories of factors is used to authenticate an individual's identity. The use of only one factor does not offer much protection from misuse or malicious intrusion. This type of authentication is not reco... | Authentication | Wikipedia | 484 | 47967 | https://en.wikipedia.org/wiki/Authentication | Technology | Cryptography | null | vital_articles |
Recent research has shown the possibility of using smartphones sensors and accessories to extract some behavioral attributes such as touch dynamics, keystroke dynamics and gait recognition. These attributes are known as behavioral biometrics and could be used to verify or identify users implicitly and continuously on s... | Authentication | Wikipedia | 483 | 47967 | https://en.wikipedia.org/wiki/Authentication | Technology | Cryptography | null | vital_articles |
In their anti-counterfeiting technology guide, the EUIPO Observatory on Infringements of Intellectual Property Rights categorizes the main anti-counterfeiting technologies on the market currently into five main categories: electronic, marking, chemical and physical, mechanical, and technologies for digital media.
Prod... | Authentication | Wikipedia | 289 | 47967 | https://en.wikipedia.org/wiki/Authentication | Technology | Cryptography | null | vital_articles |
Packaging
Packaging and labeling can be engineered to help reduce the risks of counterfeit consumer goods or the theft and resale of products. Some package constructions are more difficult to copy and some have pilfer indicating seals. Counterfeit goods, unauthorized sales (diversion), material substitution and tamperi... | Authentication | Wikipedia | 343 | 47967 | https://en.wikipedia.org/wiki/Authentication | Technology | Cryptography | null | vital_articles |
Information content
Literary forgery can involve imitating the style of a famous author. If an original manuscript, typewritten text, or recording is available, then the medium itself (or its packaging – anything from a box to e-mail headers) can help prove or disprove the authenticity of the document. However, text, a... | Authentication | Wikipedia | 459 | 47967 | https://en.wikipedia.org/wiki/Authentication | Technology | Cryptography | null | vital_articles |
Historically, fingerprints have been used as the most authoritative method of authentication, but court cases in the US and elsewhere have raised fundamental doubts about fingerprint reliability. Outside of the legal system as well, fingerprints are easily spoofable, with British Telecom's top computer security officia... | Authentication | Wikipedia | 407 | 47967 | https://en.wikipedia.org/wiki/Authentication | Technology | Cryptography | null | vital_articles |
A polder () is a low-lying tract of land that forms an artificial hydrological entity, enclosed by embankments known as dikes. The three types of polder are:
Land reclaimed from a body of water, such as a lake or the seabed
Flood plains separated from the sea or river by a dike
Marshes separated from the surroundi... | Polder | Wikipedia | 425 | 48065 | https://en.wikipedia.org/wiki/Polder | Physical sciences | Artificial landforms | null | vital_articles |
The Netherlands has a large area of polders: as much as 20% of the land area has at some point in the past been reclaimed from the sea, thus contributing to the development of the country. IJsselmeer is the most famous polder project of the Netherlands. Some other countries which have polders are Bangladesh, Belgium, C... | Polder | Wikipedia | 455 | 48065 | https://en.wikipedia.org/wiki/Polder | Physical sciences | Artificial landforms | null | vital_articles |
The 1953 flood disaster prompted a new approach to the design of dikes and other water-retaining structures, based on an acceptable probability of overflowing. Risk is defined as the product of probability and consequences. The potential damage in lives, property, and rebuilding costs is compared with the potential cos... | Polder | Wikipedia | 490 | 48065 | https://en.wikipedia.org/wiki/Polder | Physical sciences | Artificial landforms | null | vital_articles |
History
The Jiangnan region, at the Yangtze River Delta, has a long history of constructing polders. Most of these projects were performed between the 10th and 13th centuries. The Chinese government also assisted local communities in constructing dikes for swampland water drainage. The Lijia (里甲) self-monitoring system... | Polder | Wikipedia | 416 | 48065 | https://en.wikipedia.org/wiki/Polder | Physical sciences | Artificial landforms | null | vital_articles |
Achtermeer, the oldest polder, from 1533
Alblasserwaard, containing the windmills of Kinderdijk, a World Heritage Site
Alkmaar
Andijk
Anna Paulownapolder
Beemster, a World Heritage Site
Bijlmermeer
Flevopolder, the largest artificial island in the world, last part drained in 1968
's-Gravesloot
Haarlemmermeer, ... | Polder | Wikipedia | 466 | 48065 | https://en.wikipedia.org/wiki/Polder | Physical sciences | Artificial landforms | null | vital_articles |
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