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https://en.wikipedia.org/wiki/Blindsight | Blindsight is the ability of people who are cortically blind to respond to visual stimuli that they do not consciously see due to lesions in the primary visual cortex, also known as the striate cortex or Brodmann Area 17. The term was coined by Lawrence Weiskrantz and his colleagues in a paper published in a 1974 issue of Brain. A previous paper studying the discriminatory capacity of a cortically blind patient was published in Nature in 1973. The assumed existence of blindsight is controversial, with some arguing that it is merely degraded conscious vision.
Type classification
The majority of studies on blindsight are conducted on patients who are hemianopic, i.e. blind in one half of their visual field. Following the destruction of the left or right striate cortex, patients are asked to detect, localize, and discriminate amongst visual stimuli that are presented to their blind side, often in a forced-response or guessing situation, even though they may not consciously recognize the visual stimulus. Research shows that such blind patients may achieve a higher accuracy than would be expected from chance alone.
Type 1 blindsight is the term given to this ability to guess—at levels significantly above chance—aspects of a visual stimulus (such as location or type of movement) without any conscious awareness of any stimuli. Type 2 blindsight occurs when patients claim to have a feeling that there has been a change within their blind area—e.g. movement—but that it was not a visual percept. The re-classification of blindsight into Type 1 and Type 2 was made after it was shown that the most celebrated blindsight patient, "GY", was in fact usually conscious of stimuli presented to his blind field if the stimuli had certain specific characteristics, namely being of high contrast and moving fast (at speeds in excess of 20 degrees per second).
In the aftermath of the First World War, a neurologist, George Riddoch, had described patients who had been blinded by gunshot w |
https://en.wikipedia.org/wiki/Memory%20management%20unit | A memory management unit (MMU), sometimes called paged memory management unit (PMMU), is a computer hardware unit that examines all memory references on the memory bus, translating these requests, known as virtual memory addresses, into physical addresses in main memory.
In modern systems, programs generally have addresses that access the theoretical maximum memory of the computer architecture, 32 or 64 bits. The MMU maps the addresses from each program into separate areas in physical memory, which is generally much smaller than the theoretical maximum. This is possible because programs rarely use large amounts of memory at any one time.
Most modern operating systems (OS) work in concert with the MMU to provide virtual memory (VM) support. The MMU tracks memory use in fixed-size blocks known as pages, and if a program refers to a location in a page that is not in physical memory, the MMU will cause an interrupt to the operating system. The OS will then select a lesser-used block in memory, write it to backing storage such as a hard drive if it's been modified since it was read in, read the page from backing storage into that block, and set up the MMU to map the block to the originally requested page so the program can use it. This is known as demand paging.
Modern MMUs generally perform additional memory-related tasks as well. Memory protection blocks attempts by a program to access memory it has not previously requested, which prevents a misbehaving program from using up all memory or malicious code from reading data from another program. They also often manage a processor cache, which stores recently accessed data in a very fast memory and thus reduces the need to talk to the slower main memory. In some implementations, they are also responsible for bus arbitration, controlling access to the memory bus among the many parts of the computer that desire access.
Prior to VM systems becoming widespread in the 1990s, earlier MMU designs were more varied. Common amon |
https://en.wikipedia.org/wiki/Photomultiplier%20tube | Photomultiplier tubes (photomultipliers or PMTs for short) are extremely sensitive detectors of light in the ultraviolet, visible, and near-infrared ranges of the electromagnetic spectrum. They are members of the class of vacuum tubes, more specifically vacuum phototubes. These detectors multiply the current produced by incident light by as much as 100 million times or 108 (i.e., 160 dB), in multiple dynode stages, enabling (for example) individual photons to be detected when the incident flux of light is low.
The combination of high gain, low noise, high frequency response or, equivalently, ultra-fast response, and large area of collection has maintained photomultipliers an essential place in low light level spectroscopy, confocal microscopy, Raman spectroscopy, fluorescence spectroscopy, nuclear and particle physics, astronomy, medical diagnostics including blood tests, medical imaging, motion picture film scanning (telecine), radar jamming, and high-end image scanners known as drum scanners. Elements of photomultiplier technology, when integrated differently, are the basis of night vision devices. Research that analyzes light scattering, such as the study of polymers in solution, often uses a laser and a PMT to collect the scattered light data.
Semiconductor devices, particularly silicon photomultipliers and avalanche photodiodes, are alternatives to classical photomultipliers; however, photomultipliers are uniquely well-suited for applications requiring low-noise, high-sensitivity detection of light that is imperfectly collimated.
Structure and operating principles
Photomultipliers are typically constructed with an evacuated glass housing (using an extremely tight and durable glass-to-metal seal like other vacuum tubes), containing a photocathode, several dynodes, and an anode. Incident photons strike the photocathode material, which is usually a thin vapor-deposited conducting layer on the inside of the entry window of the device. Electrons are ejected from |
https://en.wikipedia.org/wiki/List%20of%20data%20structures | This is a list of well-known data structures. For a wider list of terms, see list of terms relating to algorithms and data structures. For a comparison of running times for a subset of this list see comparison of data structures.
Data types
Primitive types
Boolean, true or false.
Character
Floating-point representation of a finite subset of the rationals.
Including single-precision and double-precision IEEE 754 floats, among others
Fixed-point representation of the rationals
Integer, a direct representation of either the integers or the non-negative integers
Reference, sometimes erroneously referred to as a pointer or handle, is a value that refers to another value, possibly including itself
Symbol, a unique identifier
Enumerated type, a set of symbols
Composite types or non-primitive type
Array, a sequence of elements of the same type stored contiguously in memory
Record (also called a structure or struct), a collection of fields
Product type (also called a tuple), a record in which the fields are not named
String, a sequence of characters representing text
Union, a datum which may be one of a set of types
Tagged union (also called a variant, discriminated union or sum type), a union with a tag specifying which type the data is
Abstract data types
Container
List
Tuple
Associative array, Map
Multimap
Set
Multiset (bag)
Stack
Queue (example Priority queue)
Double-ended queue
Graph (example Tree, Heap)
Some properties of abstract data types:
"Ordered" means that the elements of the data type have some kind of explicit order to them, where an element can be considered "before" or "after" another element. This order is usually determined by the order in which the elements are added to the structure, but the elements can be rearranged in some contexts, such as sorting a list. For a structure that isn't ordered, on the other hand, no assumptions can be made about the ordering of the elements (although a physical implementation of these data types will often a |
https://en.wikipedia.org/wiki/Molecular%20engineering | Molecular engineering is an emerging field of study concerned with the design and testing of molecular properties, behavior and interactions in order to assemble better materials, systems, and processes for specific functions. This approach, in which observable properties of a macroscopic system are influenced by direct alteration of a molecular structure, falls into the broader category of “bottom-up” design.
Molecular engineering is highly interdisciplinary by nature, encompassing aspects of chemical engineering, materials science, bioengineering, electrical engineering, physics, mechanical engineering, and chemistry. There is also considerable overlap with nanotechnology, in that both are concerned with the behavior of materials on the scale of nanometers or smaller. Given the highly fundamental nature of molecular interactions, there are a plethora of potential application areas, limited perhaps only by one's imagination and the laws of physics. However, some of the early successes of molecular engineering have come in the fields of immunotherapy, synthetic biology, and printable electronics (see molecular engineering applications).
Molecular engineering is a dynamic and evolving field with complex target problems; breakthroughs require sophisticated and creative engineers who are conversant across disciplines. A rational engineering methodology that is based on molecular principles is in contrast to the widespread trial-and-error approaches common throughout engineering disciplines. Rather than relying on well-described but poorly-understood empirical correlations between the makeup of a system and its properties, a molecular design approach seeks to manipulate system properties directly using an understanding of their chemical and physical origins. This often gives rise to fundamentally new materials and systems, which are required to address outstanding needs in numerous fields, from energy to healthcare to electronics. Additionally, with the increased soph |
https://en.wikipedia.org/wiki/List%20of%20psychological%20research%20methods | A wide range of research methods are used in psychology. These methods vary by the sources from which information is obtained, how that information is sampled, and the types of instruments that are used in data collection. Methods also vary by whether they collect qualitative data, quantitative data or both.
Qualitative psychological research findings are not arrived at by statistical or other quantitative procedures. Quantitative psychological research findings result from mathematical modeling and statistical estimation or statistical inference. The two types of research differ in the methods employed, rather than the topics they focus on.
There are three main types of psychological research:
Correlational research
Descriptive research
Experimental research
Common methods
Common research designs and data collection methods include:
Archival research
Case study uses different research methods (e.g. interview, observation, self-report questionnaire) with a single case or small number of cases.
Computer simulation (modeling)
Ethnography
Event sampling methodology, also referred to as experience sampling methodology, diary study, or ecological momentary assessment
Experiment, often with separate treatment and control groups (see scientific control and design of experiments). See Experimental psychology for many details.
Field experiment
Focus group
Interview, can be structured or unstructured.
Meta-analysis
Neuroimaging and other psychophysiological methods
Observational study, can be naturalistic (see natural experiment), participant or controlled.
Program evaluation
Quasi-experiment
Self-report inventory
Survey, often with a random sample (see survey sampling)
Twin study
Research designs vary according to the period(s) of time over which data are collected:
Retrospective cohort study: Participants are chosen, then data are collected about their past experiences.
Prospective cohort study: Participants are recruited prior to the proposed |
https://en.wikipedia.org/wiki/Voronoi%20diagram | In mathematics, a Voronoi diagram is a partition of a plane into regions close to each of a given set of objects. It can be classified also as a tessellation. In the simplest case, these objects are just finitely many points in the plane (called seeds, sites, or generators). For each seed there is a corresponding region, called a Voronoi cell, consisting of all points of the plane closer to that seed than to any other. The Voronoi diagram of a set of points is dual to that set's Delaunay triangulation.
The Voronoi diagram is named after mathematician Georgy Voronoy, and is also called a Voronoi tessellation, a Voronoi decomposition, a Voronoi partition, or a Dirichlet tessellation (after Peter Gustav Lejeune Dirichlet). Voronoi cells are also known as Thiessen polygons. Voronoi diagrams have practical and theoretical applications in many fields, mainly in science and technology, but also in visual art.
The simplest case
In the simplest case, shown in the first picture, we are given a finite set of points in the Euclidean plane. In this case each site is one of these given points, and its corresponding Voronoi cell consists of every point in the Euclidean plane for which is the nearest site: the distance to is less than or equal to the minimum distance to any other site . For one other site , the points that are closer to than to , or equally distant, form a closed half-space, whose boundary is the perpendicular bisector of line segment . Cell is the intersection of all of these half-spaces, and hence it is a convex polygon. When two cells in the Voronoi diagram share a boundary, it is a line segment, ray, or line, consisting of all the points in the plane that are equidistant to their two nearest sites. The vertices of the diagram, where three or more of these boundaries meet, are the points that have three or more equally distant nearest sites.
Formal definition
Let be a metric space with distance function . Let be a set of indices and let be a tuple |
https://en.wikipedia.org/wiki/Risk%20aversion | In economics and finance, risk aversion is the tendency of people to prefer outcomes with low uncertainty to those outcomes with high uncertainty, even if the average outcome of the latter is equal to or higher in monetary value than the more certain outcome. Risk aversion explains the inclination to agree to a situation with a more predictable, but possibly lower payoff, rather than another situation with a highly unpredictable, but possibly higher payoff. For example, a risk-averse investor might choose to put their money into a bank account with a low but guaranteed interest rate, rather than into a stock that may have high expected returns, but also involves a chance of losing value.
Example
A person is given the choice between two scenarios: one with a guaranteed payoff, and one with a risky payoff with same average value. In the former scenario, the person receives $50. In the uncertain scenario, a coin is flipped to decide whether the person receives $100 or nothing. The expected payoff for both scenarios is $50, meaning that an individual who was insensitive to risk would not care whether they took the guaranteed payment or the gamble. However, individuals may have different risk attitudes.
A person is said to be:
risk averse (or risk avoiding) - if they would accept a certain payment (certainty equivalent) of less than $50 (for example, $40), rather than taking the gamble and possibly receiving nothing.
risk neutral – if they are indifferent between the bet and a certain $50 payment.
risk loving (or risk seeking) – if they would accept the bet even when the guaranteed payment is more than $50 (for example, $60).
The average payoff of the gamble, known as its expected value, is $50. The smallest dollar amount that an individual would be indifferent to spending on a gamble or guarantee is called the certainty equivalent, which is also used as a measure of risk aversion. An individual that is risk averse has a certainty equivalent that is smaller than |
https://en.wikipedia.org/wiki/NetBIOS | NetBIOS () is an acronym for Network Basic Input/Output System. It provides services related to the session layer of the OSI model allowing applications on separate computers to communicate over a local area network. As strictly an API, NetBIOS is not a networking protocol. Operating systems of the 1980s (DOS and Novell Netware primarily) ran NetBIOS over IEEE 802.2 and IPX/SPX using the NetBIOS Frames (NBF) and NetBIOS over IPX/SPX (NBX) protocols, respectively. In modern networks, NetBIOS normally runs over TCP/IP via the NetBIOS over TCP/IP (NBT) protocol. NetBIOS is also used for identifying system names in TCP/IP (Windows). Simply stated, it is a protocol that allows communication of data for files and printers through the Session Layer of the OSI Model in a LAN.
History and terminology
NetBIOS is an operating system-level API that allows applications on computers to communicate with one another over a local area network (LAN). The API was created in 1983 by Sytek Inc. for software communication over IBM PC Network LAN technology. On IBM PC Network, as an API alone, NetBIOS relied on proprietary Sytek networking protocols for communication over the wire.
In 1985, IBM went forward with the Token Ring network scheme and produced an emulator of Sytek's NetBIOS API to allow NetBIOS-aware applications from the PC-Network era to work over IBM's new Token Ring hardware. This IBM emulator, named NetBIOS Extended User Interface (NetBEUI), expanded the base NetBIOS API created by Sytek with, among other things, the ability to deal with the greater node capacity of Token Ring. A new networking protocol, NBF, was simultaneously produced by IBM to allow its NetBEUI API (their enhanced NetBIOS API) to provide its services over Token Ring – specifically, at the IEEE 802.2 Logical Link Control layer.
In 1985, Microsoft created its own implementation of the NetBIOS API for its MS-Net networking technology. As in the case of IBM's Token Ring, the services of Microsoft's NetB |
https://en.wikipedia.org/wiki/OASIS%20%28organization%29 | The Organization for the Advancement of Structured Information Standards (OASIS; ) is a nonprofit consortium that works on the development, convergence, and adoption of open standards for cybersecurity, blockchain, Internet of things (IoT), emergency management, cloud computing, legal data exchange, energy, content technologies, and other areas.
History
OASIS was founded under the name "SGML Open" in 1993. It began as a trade association of Standard Generalized Markup Language (SGML) tool vendors to cooperatively promote the adoption of SGML through mainly educational activities, though some amount of technical activity was also pursued including an update of the CALS Table Model specification and specifications for fragment interchange and entity management.
In 1998, with the movement of the industry to XML, SGML Open changed its emphasis from SGML to XML, and changed its name to OASIS Open to be inclusive of XML and reflect an expanded scope of technical work and standards. The focus of the consortium's activities also moved from promoting adoption (as XML was getting much attention on its own) to developing technical specifications. In July 2000 a new technical committee process was approved. With the adoption of the process the manner in which technical committees were created, operated, and progressed their work was regularized. At the adoption of the process there were five technical committees; by 2004 there were nearly 70.
During 1999, OASIS was approached by UN/CEFACT, the committee of the United Nations dealing with standards for business, to jointly develop a new set of specifications for electronic business. The joint initiative, called "ebXML" and which first met in November 1999, was chartered for a three-year period. At the final meeting under the original charter, in Vienna, UN/CEFACT and OASIS agreed to divide the remaining work between the two organizations and to coordinate the completion of the work through a coordinating committee. In 2004 O |
https://en.wikipedia.org/wiki/Lime%20kiln | A lime kiln is a kiln used for the calcination of limestone (calcium carbonate) to produce the form of lime called quicklime (calcium oxide). The chemical equation for this reaction is
CaCO3 + heat → CaO + CO2
This reaction can take place at anywhere above , but is generally considered to occur at (at which temperature the partial pressure of CO2 is 1 atmosphere), but a temperature around (at which temperature the partial pressure of CO2 is 3.8 atmospheres) is usually used to make the reaction proceed quickly. Excessive temperature is avoided because it produces unreactive, "dead-burned" lime.
Slaked lime (calcium hydroxide) can be formed by mixing quicklime with water.
History
Pre-pottery Neolithic
In plaster, proto-pottery, and mortar
Because it is so readily made by heating limestone, lime must have been known from the earliest times, and all the early civilizations used it in building mortars and as a stabilizer in mud renders and floors. According to finds at 'Ain Ghazal in Jordan, Yiftahel in Israel, and Abu Hureyra in Syria dating to 7500–6000 BCE, the earliest use of lime was mostly as a binder on floors and in plaster for coating walls. This use of plaster may in turn have led to the development of proto-pottery, made from lime and ash. In mortar, the oldest binder was mud. According to finds at Catal Hüyük in Turkey, mud was soon followed by clay, and then by lime in the 6th millennium BCE.
Lime use in agriculture and coal
Knowledge of its value in agriculture is also ancient, but agricultural use only became widely possible when the use of coal made it cheap in the coalfields in the late 13th century, and an account of agricultural use was given in 1523. The earliest descriptions of lime kilns differ little from those used for small-scale manufacture a century ago. Because land transportation of minerals like limestone and coal was difficult in the pre-industrial era, they were distributed by sea, and lime was most often manufactured at small |
https://en.wikipedia.org/wiki/Snowy%20Mountains%20Scheme | The Snowy Mountains Scheme, also known as the Snowy Hydro or the Snowy scheme, is a hydroelectricity and irrigation complex in south-east Australia. Near the border of New South Wales and Victoria, the scheme consists of sixteen major dams; nine power stations; two pumping stations; and of tunnels, pipelines and aqueducts that were constructed between 1949 and 1974. The Scheme was completed under the supervision of Chief Engineer, Sir William Hudson. It is the largest engineering project undertaken in Australia.
The water of the Snowy River and some of its tributaries, much of which formerly flowed southeast onto the river flats of East Gippsland, and into Bass Strait of the Tasman sea, is captured at high elevations and diverted inland to the Murray and Murrumbidgee Rivers irrigation areas. The Scheme includes two major tunnel systems constructed through the continental divide of the Snowy Mountains, known in Australia as the Great Dividing Range. The water falls and travels through large hydro-electric power stations which generate peak-load power for the Australian Capital Territory, New South Wales and Victoria. The Scheme also provides some security of water flows to the Murray-Darling basin, providing approximately of water a year to the basin for use in Australia's irrigated agriculture industry.
In 2016, the Snowy Mountains Scheme was added to the Australian National Heritage List.
History
Background
Since the 1800s, both the Murray and Murrumbidgee rivers have been subject to development and control to meet water supply and irrigation needs. By contrast, the Snowy River, that rises in the Australian Alps and flows through mountainous and practically uninhabited country until debouching onto the river flats of East Gippsland, had never been controlled in any way, neither for the production of power nor for irrigation. A great proportion of its waters flowed eastwards into the South Pacific Ocean (the Tasman Sea). The Snowy River has the highest he |
https://en.wikipedia.org/wiki/Ernst%20Zermelo | Ernst Friedrich Ferdinand Zermelo (, ; 27 July 187121 May 1953) was a German logician and mathematician, whose work has major implications for the foundations of mathematics. He is known for his role in developing Zermelo–Fraenkel axiomatic set theory and his proof of the well-ordering theorem. Furthermore, his 1929 work on ranking chess players is the first description of a model for pairwise comparison that continues to have a profound impact on various applied fields utilizing this method.
Life
Ernst Zermelo graduated from Berlin's Luisenstädtisches Gymnasium (now ) in 1889. He then studied mathematics, physics and philosophy at the University of Berlin, the University of Halle, and the University of Freiburg. He finished his doctorate in 1894 at the University of Berlin, awarded for a dissertation on the calculus of variations (Untersuchungen zur Variationsrechnung). Zermelo remained at the University of Berlin, where he was appointed assistant to Planck, under whose guidance he began to study hydrodynamics. In 1897, Zermelo went to the University of Göttingen, at that time the leading centre for mathematical research in the world, where he completed his habilitation thesis in 1899.
In 1910, Zermelo left Göttingen upon being appointed to the chair of mathematics at Zurich University, which he resigned in 1916.
He was appointed to an honorary chair at the University of Freiburg in 1926, which he resigned in 1935 because he disapproved of Adolf Hitler's regime. At the end of World War II and at his request, Zermelo was reinstated to his honorary position in Freiburg.
Research in set theory
In 1900, in the Paris conference of the International Congress of Mathematicians, David Hilbert challenged the mathematical community with his famous Hilbert's problems, a list of 23 unsolved fundamental questions which mathematicians should attack during the coming century. The first of these, a problem of set theory, was the continuum hypothesis introduced by Cantor in 18 |
https://en.wikipedia.org/wiki/Acorn%20Atom | The Acorn Atom is a home computer made by Acorn Computers Ltd from 1979 to 1982, when it was replaced by the BBC Micro. The BBC Micro began life as an upgrade to the Atom, originally known as the Proton.
The Atom was a progression of the MOS Technology 6502-based machines that the company had been making from 1979. The Atom was a cut-down Acorn System 3 without a disk drive but with an integral keyboard and cassette tape interface, sold in either kit or complete form. In 1979 it was priced between £120 in kit form, £170 () ready assembled, to over £200 for the fully expanded version with 12 KB of RAM and the floating-point extension ROM.
Hardware
The minimum Atom had 2 KB of RAM and 8 KB of ROM, with the maximum specification machine having 12 KB of each. An additional floating-point ROM was also available. The 2 KB of RAM was divided between 1 KB of Block Zero RAM (including the 256 bytes of "zero page") and 512 bytes for the screen (text mode) and only 512 bytes for programs (presumably in text mode, mode 0, and graphics not available), i.e. written in the BASIC language. When expanded up to a total of 12 KB RAM, the split is 1 KB, 5 KB for programs, and up to 6 KB for the high-resolution graphics (the screen memory could be expanded independently from the lower part of the address space). If the high-resolution graphics were not required then up to 5½ KB of the upper memory could additionally be used for program storage. The first 1 KB, i.e. Block Zero, was used by the CPU for stack storage, by the OS, and by the Atom BASIC for storage of the 27 variables.
It had an MC6847 Video Display Generator (VDG) video chip, allowing for both text and graphics modes. It could be connected to a TV or modified to output to a video monitor. Basic video memory was 1 KB but could be expanded to 6 KB. Since the MC6847 could only output at 60 Hz, meaning that the video could not be resolved on a large proportion of European TV sets, a 50 Hz PAL colour card was later made |
https://en.wikipedia.org/wiki/Atavism | In biology, an atavism is a modification of a biological structure whereby an ancestral genetic trait reappears after having been lost through evolutionary change in previous generations. Atavisms can occur in several ways, one of which is when genes for previously existing phenotypic features are preserved in DNA, and these become expressed through a mutation that either knocks out the dominant genes for the new traits or makes the old traits dominate the new one. A number of traits can vary as a result of shortening of the fetal development of a trait (neoteny) or by prolongation of the same. In such a case, a shift in the time a trait is allowed to develop before it is fixed can bring forth an ancestral phenotype. Atavisms are often seen as evidence of evolution.
In social sciences, atavism is the tendency of reversion. For example, people in the modern era reverting to the ways of thinking and acting of a former time.
The word atavism is derived from the Latin atavus—a great-great-great-grandfather or, more generally, an ancestor.
Biology
Evolutionarily traits that have disappeared phenotypically do not necessarily disappear from an organism's DNA. The gene sequence often remains, but is inactive. Such an unused gene may remain in the genome for many generations. As long as the gene remains intact, a fault in the genetic control suppressing the gene can lead to it being expressed again. Sometimes, the expression of dormant genes can be induced by artificial stimulation.
Atavisms have been observed in humans, such as with infants born with vestigial tails (called a "coccygeal process", "coccygeal projection", or "caudal appendage"). Atavism can also be seen in humans who possess large teeth, like those of other primates. In addition, a case of "snake heart", the presence of "coronary circulation and myocardial architecture [that closely] resemble those of the reptilian heart", has also been reported in medical literature. Atavism has also recently been induce |
https://en.wikipedia.org/wiki/GeForce%202%20series | The GeForce 2 series (NV15) is the second generation of Nvidia's GeForce graphics processing units (GPUs). Introduced in 2000, it is the successor to the GeForce 256.
The GeForce 2 family comprised a number of models: GeForce 2 GTS, GeForce 2 Pro, GeForce 2 Ultra, GeForce 2 Ti, GeForce 2 Go and the GeForce 2 MX series. In addition, the GeForce 2 architecture is used for the Quadro series on the Quadro 2 Pro, 2 MXR, and 2 EX cards with special drivers meant to accelerate computer-aided design applications.
Architecture
The GeForce 2 architecture is similar to the previous GeForce 256 line but with various improvements. Compared to the 220 nm GeForce 256, the GeForce 2 is built on a 180 nm manufacturing process, making the silicon more dense and allowing for more transistors and a higher clock speed. The most significant change for 3D acceleration is the addition of a second texture mapping unit to each of the four pixel pipelines. Some say the second TMU was there in the original Geforce NSR (NVIDIA Shading Rasterizer) but dual-texturing was disabled due to a hardware bug; NSR's unique ability to do single-cycle trilinear texture filtering supports this suggestion. This doubles the texture fillrate per clock compared to the previous generation and is the reasoning behind the GeForce 2 GTS's naming suffix: GigaTexel Shader (GTS). The GeForce 2 also formally introduces the NSR (Nvidia Shading Rasterizer), a primitive type of programmable pixel pipeline that is somewhat similar to later pixel shaders. This functionality is also present in GeForce 256 but was unpublicized. Another hardware enhancement is an upgraded video processing pipeline, called HDVP (high definition video processor). HDVP supports motion video playback at HDTV-resolutions (MP@HL).
In 3D benchmarks and gaming applications, the GeForce 2 GTS outperforms its predecessor by up to 40%. In OpenGL games (such as Quake III), the card outperforms the ATI Radeon DDR and 3dfx Voodoo 5 5500 cards in both 16 |
https://en.wikipedia.org/wiki/Aphasiology | Aphasiology is the study of language impairment usually resulting from brain damage, due to neurovascular accident—hemorrhage, stroke—or associated with a variety of neurodegenerative diseases, including different types of dementia. These specific language deficits, termed aphasias, may be defined as impairments of language production or comprehension that cannot be attributed to trivial causes such as deafness or oral paralysis. A number of aphasias have been described, but two are best known: expressive aphasia (Broca's aphasia) and receptive aphasia (Wernicke's or sensory aphasia).
Acute aphasias
Acute aphasias are often the result of tissue damage following a stroke.
Expressive aphasia
First described by the French neurologist Paul Broca in the nineteenth century, expressive aphasia causes the speech of those affected to display a considerable vocabulary but to show grammatical deficits. It is characterized by a halting speech consisting mainly of content words, i.e. nouns and verbs, and, at least in English, distinctly lacking small grammatical function words such as articles and prepositions. This observation gave rise to the terms telegraphic speech and, more recently, agrammatism. The extent to which expressive aphasics retain knowledge of grammar is a matter of considerable controversy. Nonetheless, because their comprehension of spoken language is mostly preserved, and because their speech is usually good enough to get their point across, the agrammatic nature of their speech suggests that the disorder chiefly involves the expressive mechanisms of language that turn thoughts into well-formed sentences.
The view of expressive aphasia as an expressive disorder is supported by its frequent co-occurrence with facial motor difficulties, and its anatomical localization. Although expressive aphasia may be caused by brain damage to many regions, it is most commonly associated with the inferior frontal gyrus, a region that overlaps with motor cortex cont |
https://en.wikipedia.org/wiki/Racetrack%20%28game%29 | Racetrack is a paper and pencil game that simulates a car race, played by two or more players. The game is played on a squared sheet of paper, with a pencil line tracking each car's movement. The rules for moving represent a car with a certain inertia and physical limits on traction, and the resulting line is reminiscent of how real racing cars move. The game requires players to slow down before bends in the track, and requires some foresight and planning for successful play. The game is popular as an educational tool teaching vectors.
The game is also known under names such as Vector Formula, Vector Rally, Vector Race, Graph Racers, PolyRace, Paper and pencil racing, or the Graph paper race game.
The basic game
The rules are here explained in simple terms. As will follow from a later section, if the mathematical concept of vectors is known, some of the rules may be stated more briefly. The rules may also be stated in terms of the physical concepts velocity and acceleration.
The track
On a sheet of quadrille paper ("quad pad", e.g. Letter preprinted with a 1/4" square grid, or A4 with a 5 mm square grid), a freehand loop is drawn as the outer boundary of the racetrack. A large ellipse will do for a first game, but some irregularities are needed to make the game interesting. Another freehand loop is drawn inside the first. It can be more or less parallel with the outer loop, or the track can have wider and narrower spots (pinch spots), with usually at least two squares between the loops. A straight starting and finishing line is drawn across the two loops, and a direction for the race is chosen (e.g., counter clockwise).
Preparing to play
The order of players is agreed upon. Each player chooses a color or mark (such as x and o) to represent the player's car. Each player marks a starting point for their car - a grid intersection at or behind the starting line.
The moves
All moves will be from one grid point to another grid point. Each grid point has eight neighb |
https://en.wikipedia.org/wiki/DMZ%20%28computing%29 | In computer security, a DMZ or demilitarized zone (sometimes referred to as a perimeter network or screened subnet) is a physical or logical subnetwork that contains and exposes an organization's external-facing services to an untrusted, usually larger, network such as the Internet. The purpose of a DMZ is to add an additional layer of security to an organization's local area network (LAN): an external network node can access only what is exposed in the DMZ, while the rest of the organization's network is protected behind a firewall. The DMZ functions as a small, isolated network positioned between the Internet and the private network.
This is not to be confused with a DMZ host, a feature present in some home routers which frequently differs greatly from an ordinary DMZ.
The name is from the term demilitarized zone, an area between states in which military operations are not permitted.
Rationale
The DMZ is seen as not belonging to either network bordering it. This metaphor applies to the computing use as the DMZ acts as a gateway to the public Internet. It is neither as secure as the internal network, nor as insecure as the public internet.
In this case, the hosts most vulnerable to attack are those that provide services to users outside of the local area network, such as e-mail, Web and Domain Name System (DNS) servers. Because of the increased potential of these hosts suffering an attack, they are placed into this specific subnetwork in order to protect the rest of the network in case any of them become compromised.
Hosts in the DMZ are permitted to have only limited connectivity to specific hosts in the internal network, as the content of DMZ is not as secure as the internal network. Similarly, communication between hosts in the DMZ and to the external network is also restricted to make the DMZ more secure than the Internet and suitable for housing these special purpose services. This allows hosts in the DMZ to communicate with both the internal and external |
https://en.wikipedia.org/wiki/Kerrison%20Predictor | The Kerrison Predictor was one of the first fully automated anti-aircraft fire-control systems. It was used to automate the aiming of the British Army's Bofors 40 mm guns and provide accurate lead calculations through simple inputs on three main handwheels.
The predictor could aim a gun at an aircraft based on simple inputs like the observed speed and the angle to the target. Such devices had been used on ships for gunnery control for some time, and versions such as the Vickers Predictor were available for larger anti-aircraft guns intended to be used against high-altitude bombers. Kerrison's analog computer was the first to be fast enough to be used in the demanding high-speed low-altitude role, which involved very short engagement times and high angular rates.
The design was also adopted for use in the United States, where it was produced by Singer Corporation as the M5 Antiaircraft Director, later updated as the M5A1 and M5A2. The M6 was mechanically identical, differing only in running on UK-style 50 Hz power.
History
By the late 1930s, both Vickers and Sperry had developed predictors for use against high-altitude bombers. However, low-flying aircraft presented a very different problem, with very short engagement times and high angular rates of motion, but at the same time less need for ballistic accuracy. Machine guns had been the preferred weapon against these targets, aimed by eye and swung by hand, but these no longer had the performance needed to deal with the larger and faster aircraft of the 1930s.
The British Army's new Bofors 40 mm guns were intended as their standard low-altitude anti-aircraft weapons. However, existing gunnery control systems were inadequate for the purpose; the range was too far to "guess" the lead, but at the same time close enough that the angle could change faster than the gunners could turn the traversal handles. Trying to operate a calculating gunsight at the same time was an added burden on the gunner. Making matters worse |
https://en.wikipedia.org/wiki/WebDAV | WebDAV (Web Distributed Authoring and Versioning) is a set of extensions to the Hypertext Transfer Protocol (HTTP), which allows user agents to collaboratively author contents directly in an HTTP web server by providing facilities for concurrency control and namespace operations, thus allowing Web to be viewed as a writeable, collaborative medium and not just a read-only medium. WebDAV is defined in by a working group of the Internet Engineering Task Force (IETF).
The WebDAV protocol provides a framework for users to create, change and move documents on a server. The most important features include the maintenance of properties about an author or modification date, namespace management, collections, and overwrite protection. Maintenance of properties includes such things as the creation, removal, and querying of file information. Namespace management deals with the ability to copy and move web pages within a server's namespace. Collections deal with the creation, removal, and listing of various resources. Lastly, overwrite protection handles aspects related to the locking of files. It takes advantage of existing technologies such as Transport Layer Security, digest access authentication or XML to satisfy those requirements.
Many modern operating systems provide built-in client-side support for WebDAV.
History
WebDAV began in 1996 when Jim Whitehead worked with the World Wide Web Consortium (W3C) to host two meetings to discuss the problem of distributed authoring on the World Wide Web with interested people. Tim Berners-Lee's original vision of the Web involved a medium for both reading and writing. In fact, Berners-Lee's first web browser, called WorldWideWeb, could both view and edit web pages; but, as the Web grew, it became a read-only medium for most users. Whitehead and other like-minded people wanted to transcend that limitation.
The meetings resulted in the formation of an IETF working group because the new effort would lead to extensions to HTTP, whic |
https://en.wikipedia.org/wiki/Solenoid | A solenoid () is a type of electromagnet formed by a helical coil of wire whose length is substantially greater than its diameter, which generates a controlled magnetic field. The coil can produce a uniform magnetic field in a volume of space when an electric current is passed through it.
André-Marie Ampère coined the term solenoid in 1823, having conceived of the device in 1820.
The helical coil of a solenoid does not necessarily need to revolve around a straight-line axis; for example, William Sturgeon's electromagnet of 1824 consisted of a solenoid bent into a horseshoe shape (similarly to an arc spring).
Solenoids provide magnetic focusing of electrons in vacuums, notably in television camera tubes such as vidicons and image orthicons. Electrons take helical paths within the magnetic field. These solenoids, focus coils, surround nearly the whole length of the tube.
Physics
Infinite continuous solenoid
An infinite solenoid has infinite length but finite diameter. "Continuous" means that the solenoid is not formed by discrete finite-width coils but by many infinitely thin coils with no space between them; in this abstraction, the solenoid is often viewed as a cylindrical sheet of conductive material.
The magnetic field inside an infinitely long solenoid is homogeneous and its strength neither depends on the distance from the axis nor on the solenoid's cross-sectional area.
This is a derivation of the magnetic flux density around a solenoid that is long enough so that fringe effects can be ignored. In Figure 1, we immediately know that the flux density vector points in the positive z direction inside the solenoid, and in the negative z direction outside the solenoid. We confirm this by applying the right hand grip rule for the field around a wire. If we wrap our right hand around a wire with the thumb pointing in the direction of the current, the curl of the fingers shows how the field behaves. Since we are dealing with a long solenoid, all of the componen |
https://en.wikipedia.org/wiki/Jansky | The jansky (symbol Jy, plural janskys) is a non-SI unit of spectral flux density, or spectral irradiance, used especially in radio astronomy. It is equivalent to 10−26 watts per square metre per hertz.
The flux density or monochromatic flux, , of a source is the integral of the spectral radiance, , over the source solid angle:
The unit is named after pioneering US radio astronomer Karl Guthe Jansky and is defined as
(SI)
(cgs).
Since the jansky is obtained by integrating over the whole source solid angle, it is most simply used to describe point sources; for example, the Third Cambridge Catalogue of Radio Sources (3C) reports results in janskys.
For extended sources, the surface brightness is often described with units of janskys per solid angle; for example, far-infrared (FIR) maps from the IRAS satellite are in megajanskys per steradian (MJy⋅sr−1).
Although extended sources at all wavelengths can be reported with these units, for radio-frequency maps, extended sources have traditionally been described in terms of a brightness temperature; for example the Haslam et al. 408 MHz all-sky continuum survey is reported in terms of a brightness temperature in kelvin.
Unit conversions
Jansky units are not a standard SI unit, so it may be necessary to convert the measurements made in the unit to the SI equivalent in terms of watts per square metre per hertz (W·m−2·Hz−1). However, other unit conversions are possible with respect to measuring this unit.
AB magnitude
The flux density in janskys can be converted to a magnitude basis, for suitable assumptions about the spectrum. For instance, converting an AB magnitude to a flux density in microjanskys is straightforward:
dBW·m−2·Hz−1
The linear flux density in janskys can be converted to a decibel basis, suitable for use in fields of telecommunication and radio engineering.
1 jansky is equal to −260 dBW·m−2·Hz−1, or −230 dBm·m−2·Hz−1:
Temperature units
The spectral radiance in janskys per steradian can be conver |
https://en.wikipedia.org/wiki/Biogeographic%20realm | A biogeographic realm is the broadest biogeographic division of Earth's land surface, based on distributional patterns of terrestrial organisms. They are subdivided into bioregions, which are further subdivided into ecoregions.
A biogeographic realm is also known as "ecozone", although that term may also refer to ecoregions.
Description
The realms delineate large areas of Earth's surface within which organisms have evolved in relative isolation over long periods of time, separated by geographic features, such as oceans, broad deserts, or high mountain ranges, that constitute natural barriers to migration. As such, biogeographic realm designations are used to indicate general groupings of organisms based on their shared biogeography. Biogeographic realms correspond to the floristic kingdoms of botany or zoogeographic regions of zoology.
From 1872, Alfred Russel Wallace developed a system of zoogeographic regions, extending the ornithologist Philip Sclater's system of six regions.
Biogeographic realms are characterized by the evolutionary history of the organisms they contain. They are distinct from biomes, also known as major habitat types, which are divisions of the Earth's surface based on life form, or the adaptation of animals, fungi, micro-organisms and plants to climatic, soil, and other conditions. Biomes are characterized by similar climax vegetation. Each realm may include a number of different biomes. A tropical moist broadleaf forest in Central America, for example, may be similar to one in New Guinea in its vegetation type and structure, climate, soils, etc., but these forests are inhabited by animals, fungi, micro-organisms and plants with very different evolutionary histories.
The distribution of organisms among the world's biogeographic realms has been influenced by the distribution of landmasses, as shaped by plate tectonics over the geological history of the Earth.
Concept history
The "biogeographic realms" of Udvardy were defined based on tax |
https://en.wikipedia.org/wiki/Palearctic%20realm | The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa.
The realm consists of several bioregions: the Euro-Siberian region; the Mediterranean Basin; the Sahara and Arabian Deserts; and Western, Central and East Asia. The Palaearctic realm also has numerous rivers and lakes, forming several freshwater ecoregions.
The term 'Palearctic' was first used in the 19th century, and is still in use as the basis for zoogeographic classification.
History
In an 1858 paper for the Proceedings of the Linnean Society, British zoologist Philip Sclater first identified six terrestrial zoogeographic realms of the world: Palaearctic, Aethiopian/Afrotropic, Indian/Indomalayan, Australasian, Nearctic, and Neotropical. The six indicated general groupings of fauna, based on shared biogeography and large-scale geographic barriers to migration.
Alfred Wallace adopted Sclater's scheme for his book The Geographical Distribution of Animals, published in 1876. This is the same scheme that persists today, with relatively minor revisions, and the addition of two more realms: Oceania and the Antarctic realm.
Major ecological regions
The Palearctic realm includes mostly boreal/subarctic-climate and temperate-climate ecoregions, which run across Eurasia from western Europe to the Bering Sea.
Euro-Siberian region
The boreal and temperate Euro-Siberian region is the Palearctic's largest biogeographic region, which transitions from tundra in the northern reaches of Russia and Scandinavia to the vast taiga, the boreal coniferous forests which run across the continent. South of the taiga are a belt of temperate broadleaf and mixed forests and temperate coniferous forests. This vast Euro-Siberian region is characterized by many shared plant and animal species, and has many affinities with the temperate and boreal regions of the Nearctic realm of North America. Eurasia |
https://en.wikipedia.org/wiki/Snub%20cube | In geometry, the snub cube, or snub cuboctahedron, is an Archimedean solid with 38 faces: 6 squares and 32 equilateral triangles. It has 60 edges and 24 vertices.
It is a chiral polyhedron; that is, it has two distinct forms, which are mirror images (or "enantiomorphs") of each other. The union of both forms is a compound of two snub cubes, and the convex hull of both sets of vertices is a truncated cuboctahedron.
Kepler first named it in Latin as cubus simus in 1619 in his Harmonices Mundi. H. S. M. Coxeter, noting it could be derived equally from the octahedron as the cube, called it snub cuboctahedron, with a vertical extended Schläfli symbol , and representing an alternation of a truncated cuboctahedron, which has Schläfli symbol .
Dimensions
For a snub cube with edge length , its surface area and volume are:
where t is the tribonacci constant
If the original snub cube has edge length 1, its dual pentagonal icositetrahedron has side lengths
.
Cartesian coordinates
Cartesian coordinates for the vertices of a snub cube are all the even permutations of
(±1, ±, ±t)
with an even number of plus signs, along with all the odd permutations with an odd number of plus signs, where t ≈ 1.83929 is the tribonacci constant. Taking the even permutations with an odd number of plus signs, and the odd permutations with an even number of plus signs, gives a different snub cube, the mirror image. Taking all of them together yields the compound of two snub cubes.
This snub cube has edges of length , a number which satisfies the equation
and can be written as
To get a snub cube with unit edge length, divide all the coordinates above by the value α given above.
Orthogonal projections
The snub cube has two special orthogonal projections, centered, on two types of faces: triangles, and squares, correspond to the A2 and B2 Coxeter planes.
Spherical tiling
The snub cube can also be represented as a spherical tiling, and projected onto the plane via a stereographic projection. |
https://en.wikipedia.org/wiki/Keygen | A key generator (key-gen) is a computer program that generates a product licensing key, such as a serial number, necessary to activate for use of a software application. Keygens may be legitimately distributed by software manufacturers for licensing software in commercial environments where software has been licensed in bulk for an entire site or enterprise, or they may be developed and distributed illegitimately in circumstances of copyright infringement or software piracy.
Illegitimate key generators are typically programmed and distributed by software crackers in the warez scene. These keygens often play music, which may include the genres dubstep, chiptunes, sampled loops or anything that the programmer desires. Chiptunes are often preferred due to their small size. Keygens can have artistic user interfaces or kept simple and display only a cracking group or cracker's logo.
Software licensing
A software license is a legal instrument that governs the usage and distribution of computer software. Often, such licenses are enforced by implementing in the software a product activation or digital rights management (DRM) mechanism, seeking to prevent unauthorized use of the software by issuing a code sequence that must be entered into the application when prompted or stored in its configuration.
Key verification
Many programs attempt to verify or validate licensing keys over the Internet by establishing a session with a licensing application of the software publisher. Advanced keygens bypass this mechanism, and include additional features for key verification, for example by generating the validation data which would otherwise be returned by an activation server. If the software offers phone activation then the keygen could generate the correct activation code to finish activation. Another method that has been used is activation server emulation, which patches the program memory to "see" the keygen as the de facto activation server.
Multi-keygen
A multi-keygen is a |
https://en.wikipedia.org/wiki/Dymaxion%20map | The Dymaxion map or Fuller map is a projection of a world map onto the surface of an icosahedron, which can be unfolded and flattened to two dimensions. The flat map is heavily interrupted in order to preserve shapes and sizes.
The projection was invented by Buckminster Fuller. The March 1, 1943, edition of Life magazine included a photographic essay titled "Life Presents R. Buckminster Fuller's Dymaxion World". The article included several examples of its use together with a pull-out section that could be assembled as a "three-dimensional approximation of a globe or laid out as a flat map, with which the world may be fitted together and rearranged to illuminate special aspects of its geography". Fuller applied for a patent in the United States in February 1944, showing a projection onto a cuboctahedron, which he called "dymaxion". The patent was issued in January 1946.
In 1954, Fuller and cartographer Shoji Sadao produced the Airocean World Map, a version of the Dymaxion map that used a modified but mostly regular icosahedron as the base for the projection. The version most commonly referred to today, it depicts Earth's continents as "one island", or nearly contiguous land masses.
The Dymaxion projection is intended only for representations of the entire globe. It is not a gnomonic projection, whereby global data expands from the center point of a tangent facet outward to the edges. Instead, each triangle edge of the Dymaxion map matches the scale of a partial great circle on a corresponding globe, and other points within each facet shrink toward its middle, rather than enlarging to the peripheries. Fuller's 1980 version of the Dymaxion map was the first definition and use of a mathematical transformation process to make the map. It is a polyhedral map projection.
The name Dymaxion was applied by Fuller to several of his inventions.
Properties
Though neither conformal nor equal-area, Fuller claimed that his map had several advantages over other projections fo |
https://en.wikipedia.org/wiki/Vehicle%20dynamics | Vehicle dynamics is the study of vehicle motion, e.g., how a vehicle's forward movement changes in response to driver inputs, propulsion system outputs, ambient conditions, air/surface/water conditions, etc.
Vehicle dynamics is a part of engineering primarily based on classical mechanics.
It may be applied for motorized vehicles (such as automobiles), bicycles and motorcycles, aircraft, and watercraft.
Factors affecting vehicle dynamics
The aspects of a vehicle's design which affect the dynamics can be grouped into drivetrain and braking, suspension and steering, distribution of mass, aerodynamics and tires.
Drivetrain and braking
Automobile layout (i.e. location of engine and driven wheels)
Powertrain
Braking system
Suspension and steering
Some attributes relate to the geometry of the suspension, steering and chassis. These include:
Ackermann steering geometry
Axle track
Camber angle
Caster angle
Ride height
Roll center
Scrub radius
Steering ratio
Toe
Wheel alignment
Wheelbase
Distribution of mass
Some attributes or aspects of vehicle dynamics are purely due to mass and its distribution. These include:
Center of mass
Moment of inertia
Roll moment
Sprung mass
Unsprung mass
Weight distribution
Aerodynamics
Some attributes or aspects of vehicle dynamics are purely aerodynamic. These include:
Automobile drag coefficient
Automotive aerodynamics
Center of pressure
Downforce
Ground effect in cars
Tires
Some attributes or aspects of vehicle dynamics can be attributed directly to the tires. These include:
Camber thrust
Circle of forces
Contact patch
Cornering force
Ground pressure
Pacejka's Magic Formula
Pneumatic trail
Radial Force Variation
Relaxation length
Rolling resistance
Self aligning torque
Skid
Slip angle
Slip (vehicle dynamics)
Spinout
Steering ratio
Tire load sensitivity
Vehicle behaviours
Some attributes or aspects of vehicle dynamics are purely dynamic. These include:
Body flex
Body roll
Bump Steer
Bu |
https://en.wikipedia.org/wiki/Cubic%20equation | In algebra, a cubic equation in one variable is an equation of the form
in which is nonzero.
The solutions of this equation are called roots of the cubic function defined by the left-hand side of the equation. If all of the coefficients , , , and of the cubic equation are real numbers, then it has at least one real root (this is true for all odd-degree polynomial functions). All of the roots of the cubic equation can be found by the following means:
algebraically: more precisely, they can be expressed by a cubic formula involving the four coefficients, the four basic arithmetic operations, square roots and cube roots. (This is also true of quadratic (second-degree) and quartic (fourth-degree) equations, but not for higher-degree equations, by the Abel–Ruffini theorem.)
trigonometrically
numerical approximations of the roots can be found using root-finding algorithms such as Newton's method.
The coefficients do not need to be real numbers. Much of what is covered below is valid for coefficients in any field with characteristic other than 2 and 3. The solutions of the cubic equation do not necessarily belong to the same field as the coefficients. For example, some cubic equations with rational coefficients have roots that are irrational (and even non-real) complex numbers.
History
Cubic equations were known to the ancient Babylonians, Greeks, Chinese, Indians, and Egyptians. Babylonian (20th to 16th centuries BC) cuneiform tablets have been found with tables for calculating cubes and cube roots. The Babylonians could have used the tables to solve cubic equations, but no evidence exists to confirm that they did. The problem of doubling the cube involves the simplest and oldest studied cubic equation, and one for which the ancient Egyptians did not believe a solution existed. In the 5th century BC, Hippocrates reduced this problem to that of finding two mean proportionals between one line and another of twice its length, but could not solve this with a compas |
https://en.wikipedia.org/wiki/Hypergeometric%20distribution | In probability theory and statistics, the hypergeometric distribution is a discrete probability distribution that describes the probability of successes (random draws for which the object drawn has a specified feature) in draws, without replacement, from a finite population of size that contains exactly objects with that feature, wherein each draw is either a success or a failure. In contrast, the binomial distribution describes the probability of successes in draws with replacement.
Definitions
Probability mass function
The following conditions characterize the hypergeometric distribution:
The result of each draw (the elements of the population being sampled) can be classified into one of two mutually exclusive categories (e.g. Pass/Fail or Employed/Unemployed).
The probability of a success changes on each draw, as each draw decreases the population (sampling without replacement from a finite population).
A random variable follows the hypergeometric distribution if its probability mass function (pmf) is given by
where
is the population size,
is the number of success states in the population,
is the number of draws (i.e. quantity drawn in each trial),
is the number of observed successes,
is a binomial coefficient.
The is positive when .
A random variable distributed hypergeometrically with parameters , and is written and has probability mass function above.
Combinatorial identities
As required, we have
which essentially follows from Vandermonde's identity from combinatorics.
Also note that
This identity can be shown by expressing the binomial coefficients in terms of factorials and rearranging the latter. Additionally, it
follows from the symmetry of the problem, described in two different but interchangeable ways.
For example, consider two rounds of drawing without replacement. In the first round, out of neutral marbles are drawn from an urn without replacement and coloured green. Then the colored marbles are put back. In the se |
https://en.wikipedia.org/wiki/Kalman%20filter | For statistics and control theory, Kalman filtering, also known as linear quadratic estimation (LQE), is an algorithm that uses a series of measurements observed over time, including statistical noise and other inaccuracies, and produces estimates of unknown variables that tend to be more accurate than those based on a single measurement alone, by estimating a joint probability distribution over the variables for each timeframe. The filter is named after Rudolf E. Kálmán, who was one of the primary developers of its theory.
This digital filter is sometimes termed the Stratonovich–Kalman–Bucy filter because it is a special case of a more general, nonlinear filter developed somewhat earlier by the Soviet mathematician Ruslan Stratonovich. In fact, some of the special case linear filter's equations appeared in papers by Stratonovich that were published before summer 1961, when Kalman met with Stratonovich during a conference in Moscow.
Kalman filtering has numerous technological applications. A common application is for guidance, navigation, and control of vehicles, particularly aircraft, spacecraft and ships positioned dynamically. Furthermore, Kalman filtering is a concept much applied in time series analysis used for topics such as signal processing and econometrics. Kalman filtering is also one of the main topics of robotic motion planning and control and can be used for trajectory optimization. Kalman filtering also works for modeling the central nervous system's control of movement. Due to the time delay between issuing motor commands and receiving sensory feedback, the use of Kalman filters provides a realistic model for making estimates of the current state of a motor system and issuing updated commands.
The algorithm works by a two-phase process. For the prediction phase, the Kalman filter produces estimates of the current state variables, along with their uncertainties. Once the outcome of the next measurement (necessarily corrupted with some error, inclu |
https://en.wikipedia.org/wiki/Thyristor | A thyristor () is a solid-state semiconductor device with four layers of alternating P- and N-type materials used for high-power applications. It acts as a bistable switch (or a latch). There are two designs, differing in what triggers the conducting state. In a three-lead thyristor, a small current on its gate lead controls the larger current of the anode-to-cathode path. In a two-lead thyristor, conduction begins when the potential difference between the anode and cathode themselves is sufficiently large (breakdown voltage). The thyristor continues conducting until the voltage across the device is reverse-biased, the voltage is removed (by some other means), or through the control gate signal on newer types.
Some sources define "silicon-controlled rectifier" (SCR) and "thyristor" as synonymous. Other sources define thyristors as more complex devices that incorporate at least four layers of alternating N-type and P-type substrate.
The first thyristor devices were released commercially in 1956. Because thyristors can control a relatively large amount of power and voltage with a small device, they find wide application in control of electric power, ranging from light dimmers and electric motor speed control to high-voltage direct-current power transmission. Thyristors may be used in power-switching circuits, relay-replacement circuits, inverter circuits, oscillator circuits, level-detector circuits, chopper circuits, light-dimming circuits, low-cost timer circuits, logic circuits, speed-control circuits, phase-control circuits, etc. Originally, thyristors relied only on current reversal to turn them off, making them difficult to apply for direct current; newer device types can be turned on and off through the control gate signal. The latter is known as a gate turn-off thyristor, or GTO thyristor.
Unlike transistors, thyristors have a two-valued switching characteristic, meaning that a thyristor can only be fully on or off, while a transistor can lie in between on |
https://en.wikipedia.org/wiki/Apollo/Domain | Apollo/Domain was a range of workstations developed and produced by Apollo Computer from circa 1980 to 1989. The machines were built around the Motorola 68k family of processors, except for the DN10000, which had from one to four of Apollo's RISC processors, named PRISM.
Operating system
The original operating system was Apollo's own product called Aegis, which was later renamed to Domain/OS. The Aegis and Domain/OS system offered advanced features for the time, for example an object oriented filesystem, network transparency, diskless booting, a graphical user interface and, in Domain/OS, interoperability with BSD, System V and POSIX.
Hardware
An Apollo workstation resembled a modern PC, with base unit, keyboard, mouse, and screen. Early models were housed in short (about 2 ft high) 19" rack cabinets that would be set beside a desk or under a table. The DN300 and later DN330 were designed as integrated units with system and monitor in one unit and fit easily on a desk. Every Apollo system (even standalones) had to include at least one network interface. Originally the only option was the 12 Mbit/s Apollo Token Ring (ATR). Over time, 10 Mbit/s Ethernet was added as an option. It has been stated that the IBM Token Ring was an option - this was never available. The ATR was generally the best choice, since it was extremely scalable; whilst the Ethernet of the time suffered serious performance loss as extra machines were added to the network, this was not true of ATR, which could easily have over a hundred machines on one network. One drawback was that, unlike Ethernet, one machine failure (which could easily happen given a single faulty connector) stopped the entire network. For this reason, Apollo provided an optional (but strongly recommended) network cabling system of bypass switches and quick connect boxes which allowed machines to be disconnected and moved without problems. Apollo Token Ring networks used 75 ohm RG-6U coaxial cabling.
Networking
The network |
https://en.wikipedia.org/wiki/Discrete%20logarithm | In mathematics, for given real numbers a and b, the logarithm logb a is a number x such that . Analogously, in any group G, powers bk can be defined for all integers k, and the discrete logarithm logb a is an integer k such that . In number theory, the more commonly used term is index: we can write x = indr a (mod m) (read "the index of a to the base r modulo m") for rx ≡ a (mod m) if r is a primitive root of m and gcd(a,m) = 1.
Discrete logarithms are quickly computable in a few special cases. However, no efficient method is known for computing them in general. Several important algorithms in public-key cryptography, such as ElGamal, base their security on the assumption that the discrete logarithm problem (DLP) over carefully chosen groups has no efficient solution.
Definition
Let G be any group. Denote its group operation by multiplication and its identity element by 1. Let b be any element of G. For any positive integer k, the expression bk denotes the product of b with itself k times:
Similarly, let b−k denote the product of b−1 with itself k times. For k = 0, the kth power is the identity: .
Let a also be an element of G. An integer k that solves the equation is termed a discrete logarithm (or simply logarithm, in this context) of a to the base b. One writes k = logb a.
Examples
Powers of 10
The powers of 10 are
For any number a in this list, one can compute log10 a. For example, log10 10000 = 4, and log10 0.001 = −3. These are instances of the discrete logarithm problem.
Other base-10 logarithms in the real numbers are not instances of the discrete logarithm problem, because they involve non-integer exponents. For example, the equation log10 53 = 1.724276… means that 101.724276… = 53. While integer exponents can be defined in any group using products and inverses, arbitrary real exponents, such as this 1.724276…, require other concepts such as the exponential function.
In group-theoretic terms, the powers of 10 form a cyclic group G under multipli |
https://en.wikipedia.org/wiki/Negative-feedback%20amplifier | A negative-feedback amplifier (or feedback amplifier) is an electronic amplifier that subtracts a fraction of its output from its input, so that negative feedback opposes the original signal. The applied negative feedback can improve its performance (gain stability, linearity, frequency response, step response) and reduces sensitivity to parameter variations due to manufacturing or environment. Because of these advantages, many amplifiers and control systems use negative feedback.
An idealized negative-feedback amplifier as shown in the diagram is a system of three elements (see Figure 1):
an amplifier with gain AOL,
a feedback network β, which senses the output signal and possibly transforms it in some way (for example by attenuating or filtering it),
a summing circuit that acts as a subtractor (the circle in the figure), which combines the input and the transformed output.
Overview
Fundamentally, all electronic devices that provide power gain (e.g., vacuum tubes, bipolar transistors, MOS transistors) are nonlinear. Negative feedback trades gain for higher linearity (reducing distortion) and can provide other benefits. If not designed correctly, amplifiers with negative feedback can under some circumstances become unstable due to the feedback becoming positive, resulting in unwanted behavior such as oscillation. The Nyquist stability criterion developed by Harry Nyquist of Bell Laboratories is used to study the stability of feedback amplifiers.
Feedback amplifiers share these properties:
Pros:
Can increase or decrease input impedance (depending on type of feedback).
Can increase or decrease output impedance (depending on type of feedback).
Reduces total distortion if sufficiently applied (increases linearity).
Increases the bandwidth.
Desensitizes gain to component variations.
Can control step response of amplifier.
Cons:
May lead to instability if not designed carefully.
Amplifier gain decreases.
Input and output impedances of a negative-feedba |
https://en.wikipedia.org/wiki/Knaster%E2%80%93Tarski%20theorem | In the mathematical areas of order and lattice theory, the Knaster–Tarski theorem, named after Bronisław Knaster and Alfred Tarski, states the following:
Let (L, ≤) be a complete lattice and let f : L → L be an order-preserving (monotonic) function w.r.t. ≤ . Then the set of fixed points of f in L forms a complete lattice under ≤ .
It was Tarski who stated the result in its most general form, and so the theorem is often known as Tarski's fixed-point theorem. Some time earlier, Knaster and Tarski established the result for the special case where L is the lattice of subsets of a set, the power set lattice.
The theorem has important applications in formal semantics of programming languages and abstract interpretation, as well as in game theory.
A kind of converse of this theorem was proved by Anne C. Davis: If every order-preserving function f : L → L on a lattice L has a fixed point, then L is a complete lattice.
Consequences: least and greatest fixed points
Since complete lattices cannot be empty (they must contain a supremum and infimum of the empty set), the theorem in particular guarantees the existence of at least one fixed point of f, and even the existence of a least fixed point (or greatest fixed point). In many practical cases, this is the most important implication of the theorem.
The least fixpoint of f is the least element x such that f(x) = x, or, equivalently, such that f(x) ≤ x; the dual holds for the greatest fixpoint, the greatest element x such that f(x) = x.
If f(lim xn) = lim f(xn) for all ascending sequences xn, then the least fixpoint of f is lim f n(0) where 0 is the least element of L, thus giving a more "constructive" version of the theorem. (See: Kleene fixed-point theorem.) More generally, if f is monotonic, then the least fixpoint of f is the stationary limit of f α(0), taking α over the ordinals, where f α is defined by transfinite induction: f α+1 = f (f α) and f γ for a limit ordinal γ is the least upper bound of the |
https://en.wikipedia.org/wiki/Apollo%20Computer | Apollo Computer Inc., founded in 1980 in Chelmsford, Massachusetts, by William Poduska (a founder of Prime Computer) and others, developed and produced Apollo/Domain workstations in the 1980s. Along with Symbolics and Sun Microsystems, Apollo was one of the first vendors of graphical workstations in the 1980s. Like computer companies at the time and unlike manufacturers of IBM PC compatibles, Apollo produced much of its own hardware and software.
Apollo was acquired by Hewlett-Packard in 1989 for US$476 million (equivalent to $ million in ), and gradually closed down over the period of 1990–1997. The brand (as "HP Apollo") was resurrected in 2014 as part of HP's high-performance computing portfolio.
History
Apollo was started in 1980, two years before Sun Microsystems.
In addition to Poduska, the founders included Dave Nelson (Engineering), Mike Greata (Engineering), Charlie Spector (COO), Bob Antonuccio (Manufacturing), Gerry Stanley (Sales and Marketing), and Dave Lubrano (Finance). The founding engineering team included Mike Sporer, Bernie Stumpf, Russ Barbour, Paul Leach, and Andy Marcuvitz.
In 1981, the company unveiled the DN100 workstation, which used the Motorola 68000 microprocessor. Apollo workstations ran Aegis (later replaced by Domain/OS), a proprietary operating system with a Unix alternative shell. Apollo's networking was particularly elegant, among the first to allow demand paging over the network, and allowing a degree of network transparency and low sysadmin-to-machine ratio.
From 1980 to 1987, Apollo was the largest manufacturer of network workstations. Its quarterly sales exceeded $100 million for the first time in late 1986, and by the end of that year, it had the largest worldwide share of the engineering workstations market, at twice the market share of the number two, Sun Microsystems. At the end of 1987, it was third in market share after Digital Equipment Corporation and Sun, but ahead of Hewlett-Packard and IBM. Apollo's largest cust |
https://en.wikipedia.org/wiki/NMEA%200183 | NMEA 0183 is a combined electrical and data specification for communication between marine electronics such as echo sounder, sonars, anemometer, gyrocompass, autopilot, GPS receivers and many other types of instruments. It has been defined and is controlled by the National Marine Electronics Association (NMEA). It replaces the earlier NMEA 0180 and NMEA 0182 standards. In leisure marine applications it is slowly being phased out in favor of the newer NMEA 2000 standard, though NMEA 0183 remains the norm in commercial shipping.
Details
The electrical standard that is used is EIA-422, also known as RS-422, although most hardware with NMEA-0183 outputs are also able to drive a single EIA-232 port. Although the standard calls for isolated inputs and outputs, there are various series of hardware that do not adhere to this requirement.
The NMEA 0183 standard uses a simple ASCII, serial communications protocol that defines how data are transmitted in a "sentence" from one "talker" to multiple "listeners" at a time. Through the use of intermediate expanders, a talker can have a unidirectional conversation with a nearly unlimited number of listeners, and using multiplexers, multiple sensors can talk to a single computer port.
At the application layer, the standard also defines the contents of each sentence (message) type, so that all listeners can parse messages accurately.
While NMEA 0183 only defines an RS-422 transport, there also exists a de facto standard in which the sentences from NMEA0183 are placed in UDP datagrams (one sentence per packet) and sent over an IP network.
The NMEA standard is proprietary and sells for at least US$2000 (except for members of the NMEA) as of September 2020. However, much of it has been reverse-engineered from public sources.
UART settings
There is a variation of the standard called NMEA-0183HS that specifies a baud rate of 38,400. This is in general use by AIS devices.
Message structure
All transmitted data are printable ASCI |
https://en.wikipedia.org/wiki/Menarche | Menarche ( ; ) is the first menstrual cycle, or first menstrual bleeding, in female humans. From both social and medical perspectives, it is often considered the central event of female puberty, as it signals the possibility of fertility.
Girls experience menarche at different ages. Having menarche occur between the ages of 9–14 in the West is considered normal. Canadian psychological researcher Niva Piran claims that menarche or the perceived average age of puberty is used in many cultures to separate girls from activity with boys, and to begin transition into womanhood.
The timing of menarche is influenced by female biology, as well as genetic and environmental factors, especially nutritional factors. The mean age of menarche has declined over the last century, but the magnitude of the decline and the factors responsible remain subjects of contention. The worldwide average age of menarche is very difficult to estimate accurately, and it varies significantly by geographical region, race, ethnicity and other characteristics, and occurs mostly during a span of ages from 8 to 16, with a small percentage of girls having menarche by age 10, and the vast majority having it by the time they were 14.
There is a later age of onset in Asian populations compared to the West, but it too is changing with time. For example a Korean study in 2011 showed an overall average age of 12.7, with around 20% before age 12, and more than 90% by age 14. A Chinese study from 2014 published in Acta Paediatrica showed similar results (overall average of age 12.8 in 2005 down to age 12.3 in 2014) and a similar trend in time, but also similar findings about ethnic, cultural, and environmental effects.
The average age of menarche was about 12.7 years in Canada in 2001, and 12.9 in the United Kingdom. A study of girls in Istanbul, Turkey, in 2011 found the median age at menarche to be 12.7 years. In the United States, an analysis of 10,590 women aged 15–44 taken from the 2013–2017 round of th |
https://en.wikipedia.org/wiki/Cryptographically%20secure%20pseudorandom%20number%20generator | A cryptographically secure pseudorandom number generator (CSPRNG) or cryptographic pseudorandom number generator (CPRNG) is a pseudorandom number generator (PRNG) with properties that make it suitable for use in cryptography. It is also loosely known as a cryptographic random number generator (CRNG).
Background
Most cryptographic applications require random numbers, for example:
key generation
nonces
salts in certain signature schemes, including ECDSA, RSASSA-PSS
The "quality" of the randomness required for these applications varies.
For example, creating a nonce in some protocols needs only uniqueness.
On the other hand, the generation of a master key requires a higher quality, such as more entropy. And in the case of one-time pads, the information-theoretic guarantee of perfect secrecy only holds if the key material comes from a true random source with high entropy, and thus any kind of pseudorandom number generator is insufficient.
Ideally, the generation of random numbers in CSPRNGs uses entropy obtained from a high-quality source, generally the operating system's randomness API. However, unexpected correlations have been found in several such ostensibly independent processes. From an information-theoretic point of view, the amount of randomness, the entropy that can be generated, is equal to the entropy provided by the system. But sometimes, in practical situations, more random numbers are needed than there is entropy available. Also, the processes to extract randomness from a running system are slow in actual practice. In such instances, a CSPRNG can sometimes be used. A CSPRNG can "stretch" the available entropy over more bits.
Requirements
A cryptographically secure pseudorandom number generator (CSPRNG) or cryptographic pseudorandom number generator (CPRNG) is a pseudorandom number generator (PRNG) with properties that make it suitable for use in cryptography. It is also loosely known as a cryptographic random number generator (CRNG), which can be |
https://en.wikipedia.org/wiki/Whitelist | A whitelist is a list or register of entities that are being provided a particular privilege, service, mobility, access or recognition. Entities on the list will be accepted, approved and/or recognized. Whitelisting is the reverse of blacklisting, the practice of identifying entities that are denied, unrecognised, or ostracised.
Email whitelists
Spam filters often include the ability to "whitelist" certain sender IP addresses, email addresses or domain names to protect their email from being rejected or sent to a junk mail folder. These can be manually maintained by the user or system administrator - but can also refer to externally maintained whitelist services.
Non-commercial whitelists
Non-commercial whitelists are operated by various non-profit organisations, ISPs, and others interested in blocking spam. Rather than paying fees, the sender must pass a series of tests; for example, their email server must not be an open relay and have a static IP address. The operator of the whitelist may remove a server from the list if complaints are received.
Commercial whitelists
Commercial whitelists are a system by which an Internet service provider allows someone to bypass spam filters when sending email messages to its subscribers, in return for a pre-paid fee, either an annual or a per-message fee. A sender can then be more confident that their messages have reached recipients without being blocked, or having links or images stripped out of them, by spam filters. The purpose of commercial whitelists is to allow companies to reliably reach their customers by email.
Advertising whitelists
Many websites rely on ads as a source of revenue, but the use of ad blockers is increasingly common. Websites that detect an adblocker in use often ask for it to be disabled - or their site to be "added to the whitelist" - a standard feature of most adblockers.
Network whitelists
Network Whitelisting can occur at different layers of the OSI model.
LAN whitelists
LAN whitelists ar |
https://en.wikipedia.org/wiki/Inventory | Inventory (American English) or stock (British English) refers to the goods and materials that a business holds for the ultimate goal of resale, production or utilisation.
Inventory management is a discipline primarily about specifying the shape and placement of stocked goods. It is required at different locations within a facility or within many locations of a supply network to precede the regular and planned course of production and stock of materials.
The concept of inventory, stock or work in process (or work in progress) has been extended from manufacturing systems to service businesses and projects, by generalizing the definition to be "all work within the process of production—all work that is or has occurred prior to the completion of production". In the context of a manufacturing production system, inventory refers to all work that has occurred—raw materials, partially finished products, finished products prior to sale and departure from the manufacturing system. In the context of services, inventory refers to all work done prior to sale, including partially process information.
Business inventory
Reasons for keeping stock
There are five basic reasons for keeping an inventory:
Time: The time lags present in the supply chain, from supplier to user at every stage, requires that you maintain certain amounts of inventory to use in this lead time. However, in practice, inventory is to be maintained for consumption during 'variations in lead time'. Lead time itself can be addressed by ordering that many days in advance.
Seasonal demand: Demands varies periodically, but producers capacity is fixed. This can lead to stock accumulation, consider for example how goods consumed only in holidays can lead to accumulation of large stocks on the anticipation of future consumption.
Uncertainty: Inventories are maintained as buffers to meet uncertainties in demand, supply and movements of goods.
Economies of scale: Ideal condition of "one unit at a time at a place |
https://en.wikipedia.org/wiki/Time%20from%20NPL%20%28MSF%29 | The Time from NPL is a radio signal broadcast from the Anthorn Radio Station near Anthorn, Cumbria, which serves as the United Kingdom's national time reference. The time signal is derived from three atomic clocks installed at the transmitter site, and is based on time standards maintained by the UK's National Physical Laboratory (NPL) in Teddington. The service is provided by Babcock International (which acquired former providers VT Communications), under contract to the NPL. It was funded by the former Department for Business, Innovation and Skills; NPL Management Limited (NPLML) was owned by the Department for Business, Energy and Industrial Strategy (BEIS), and NPL operated as a public corporation.
The signal, also known as the MSF signal (and formerly the Rugby clock), is broadcast at a highly accurate frequency of 60 kHz and can be received throughout the UK, and in much of northern and western Europe.
The signal's carrier frequency is maintained at 60 kHz to within 2 parts in 1012, controlled by caesium atomic clocks at the radio station.
History
A radio station at Rugby was first operated by the Post Office from 1926, with the call-sign GBR. From 19 December 1927, it broadcast a 15.8 kHz time signal from the Royal Observatory which could be received worldwide. It consisted of 306 pulses in the five minutes up to and including 10:00 and 18:00 GMT, with a longer pulse at the start of each minute. Frequency-shift keying was added in 1967, making the signal harder to use as a frequency reference. The time signals, preceded by the callsign "GBR GBR TIME" in Morse code, were transmitted during the 5 minutes preceding 03:00, 09:00, 15:00 and 21:00. Transmitter GBZ on 19.6 kHz was used as a reserve, when GBR was off-air for maintenance. Eventually, time signals from GBR were terminated in November 1986 and it is no longer used as a frequency reference.
The MSF signals started in 1950, following the transmission pattern described below. They were originally int |
https://en.wikipedia.org/wiki/Clock%20signal | In electronics and especially synchronous digital circuits, a clock signal (historically also known as logic beat) is an electronic logic signal (voltage or current) which oscillates between a high and a low state at a constant frequency and is used like a metronome to synchronize actions of digital circuits. In a synchronous logic circuit, the most common type of digital circuit, the clock signal is applied to all storage devices, flip-flops and latches, and causes them all to change state simultaneously, preventing race conditions.
A clock signal is produced by an electronic oscillator called a clock generator. The most common clock signal is in the form of a square wave with a 50% duty cycle. Circuits using the clock signal for synchronization may become active at either the rising edge, falling edge, or, in the case of double data rate, both in the rising and in the falling edges of the clock cycle.
Digital circuits
Most integrated circuits (ICs) of sufficient complexity use a clock signal in order to synchronize different parts of the circuit, cycling at a rate slower than the worst-case internal propagation delays. In some cases, more than one clock cycle is required to perform a predictable action. As ICs become more complex, the problem of supplying accurate and synchronized clocks to all the circuits becomes increasingly difficult. The preeminent example of such complex chips is the microprocessor, the central component of modern computers, which relies on a clock from a crystal oscillator. The only exceptions are asynchronous circuits such as asynchronous CPUs.
A clock signal might also be gated, that is, combined with a controlling signal that enables or disables the clock signal for a certain part of a circuit. This technique is often used to save power by effectively shutting down portions of a digital circuit when they are not in use, but comes at a cost of increased complexity in timing analysis.
Single-phase clock
Most modern synchronous |
https://en.wikipedia.org/wiki/Hoare%20logic | Hoare logic (also known as Floyd–Hoare logic or Hoare rules) is a formal system with a set of logical rules for reasoning rigorously about the correctness of computer programs. It was proposed in 1969 by the British computer scientist and logician Tony Hoare, and subsequently refined by Hoare and other researchers. The original ideas were seeded by the work of Robert W. Floyd, who had published a similar system for flowcharts.
Hoare triple
The central feature of Hoare logic is the Hoare triple. A triple describes how the execution of a piece of code changes the state of the computation. A Hoare triple is of the form
where and are assertions and is a command. is named the precondition and the postcondition: when the precondition is met, executing the command establishes the postcondition. Assertions are formulae in predicate logic.
Hoare logic provides axioms and inference rules for all the constructs of a simple imperative programming language. In addition to the rules for the simple language in Hoare's original paper, rules for other language constructs have been developed since then by Hoare and many other researchers. There are rules for concurrency, procedures, jumps, and pointers.
Partial and total correctness
Using standard Hoare logic, only partial correctness can be proven. Total correctness additionally requires termination, which can be proven separately or with an extended version of the While rule. Thus the intuitive reading of a Hoare triple is: Whenever holds of the state before the execution of , then will hold afterwards, or does not terminate. In the latter case, there is no "after", so can be any statement at all. Indeed, one can choose to be false to express that does not terminate.
"Termination" here and in the rest of this article is meant in the broader sense that computation will eventually be finished, that is it implies the absence of infinite loops; it does not imply the absence of implementation limit violations (e.g. |
https://en.wikipedia.org/wiki/Johnson%E2%80%93Nyquist%20noise | Johnson–Nyquist noise (thermal noise, Johnson noise, or Nyquist noise) is the electronic noise generated by the thermal agitation of the charge carriers (usually the electrons) inside an electrical conductor at equilibrium, which happens regardless of any applied voltage. Thermal noise is present in all electrical circuits, and in sensitive electronic equipment (such as radio receivers) can drown out weak signals, and can be the limiting factor on sensitivity of electrical measuring instruments. Thermal noise increases with temperature. Some sensitive electronic equipment such as radio telescope receivers are cooled to cryogenic temperatures to reduce thermal noise in their circuits. The generic, statistical physical derivation of this noise is called the fluctuation-dissipation theorem, where generalized impedance or generalized susceptibility is used to characterize the medium.
Thermal noise in an ideal resistor is approximately white, meaning that the power spectral density is nearly constant throughout the frequency spectrum, but does decay to zero at extremely high frequencies (terahertz for room temperature). When limited to a finite bandwidth, thermal noise has a nearly Gaussian amplitude distribution.
History
This type of noise was discovered and first measured by John B. Johnson at Bell Labs in 1926. He described his findings to Harry Nyquist, also at Bell Labs, who was able to explain the results.
Derivation
As Nyquist stated in his 1928 paper, the sum of the energy in the normal modes of electrical oscillation would determine the amplitude of the noise. Nyquist used the equipartition law of Boltzmann and Maxwell. Using the concept potential energy and harmonic oscillators of the equipartition law,
where is the noise power density in (W/Hz), is the Boltzmann constant and is the temperature. Multiplying the equation by bandwidth gives the result as noise power.
where N is the noise power and Δf is the bandwidth.
Noise voltage and power
The |
https://en.wikipedia.org/wiki/Kronecker%20delta | In mathematics, the Kronecker delta (named after Leopold Kronecker) is a function of two variables, usually just non-negative integers. The function is 1 if the variables are equal, and 0 otherwise:
or with use of Iverson brackets:
For example, because , whereas because .
The Kronecker delta appears naturally in many areas of mathematics, physics, engineering and computer science, as a means of compactly expressing its definition above.
In linear algebra, the identity matrix has entries equal to the Kronecker delta:
where and take the values , and the inner product of vectors can be written as
Here the Euclidean vectors are defined as -tuples: and and the last step is obtained by using the values of the Kronecker delta to reduce the summation over .
It is common for and to be restricted to a set of the form or , but the Kronecker delta can be defined on an arbitrary set.
Properties
The following equations are satisfied:
Therefore, the matrix can be considered as an identity matrix.
Another useful representation is the following form:
This can be derived using the formula for the geometric series.
Alternative notation
Using the Iverson bracket:
Often, a single-argument notation is used, which is equivalent to setting :
In linear algebra, it can be thought of as a tensor, and is written . Sometimes the Kronecker delta is called the substitution tensor.
Digital signal processing
In the study of digital signal processing (DSP), the unit sample function represents a special case of a 2-dimensional Kronecker delta function where the Kronecker indices include the number zero, and where one of the indices is zero. In this case:
Or more generally where:
However, this is only a special case. In tensor calculus, it is more common to number basis vectors in a particular dimension starting with index 1, rather than index 0. In this case, the relation does not exist, and in fact, the Kronecker delta function and the unit sample function are d |
https://en.wikipedia.org/wiki/List%20of%20unsolved%20problems%20in%20mathematics | Many mathematical problems have been stated but not yet solved. These problems come from many areas of mathematics, such as theoretical physics, computer science, algebra, analysis, combinatorics, algebraic, differential, discrete and Euclidean geometries, graph theory, group theory, model theory, number theory, set theory, Ramsey theory, dynamical systems, and partial differential equations. Some problems belong to more than one discipline and are studied using techniques from different areas. Prizes are often awarded for the solution to a long-standing problem, and some lists of unsolved problems, such as the Millennium Prize Problems, receive considerable attention.
This list is a composite of notable unsolved problems mentioned in previously published lists, including but not limited to lists considered authoritative. Although this list may never be comprehensive, the problems listed here vary widely in both difficulty and importance.
Lists of unsolved problems in mathematics
Various mathematicians and organizations have published and promoted lists of unsolved mathematical problems. In some cases, the lists have been associated with prizes for the discoverers of solutions.
Millennium Prize Problems
Of the original seven Millennium Prize Problems listed by the Clay Mathematics Institute in 2000, six remain unsolved to date:
Birch and Swinnerton-Dyer conjecture
Hodge conjecture
Navier–Stokes existence and smoothness
P versus NP
Riemann hypothesis
Yang–Mills existence and mass gap
The seventh problem, the Poincaré conjecture, was solved by Grigori Perelman in 2003. However, a generalization called the smooth four-dimensional Poincaré conjecture—that is, whether a four-dimensional topological sphere can have two or more inequivalent smooth structures—is unsolved.
Notebooks
The Kourovka Notebook () is a collection of unsolved problems in group theory, first published in 1965 and updated many times since.
The Sverdlovsk Notebook () is a collection of |
https://en.wikipedia.org/wiki/Front-side%20bus | The front-side bus (FSB) is a computer communication interface (bus) that was often used in Intel-chip-based computers during the 1990s and 2000s. The EV6 bus served the same function for competing AMD CPUs. Both typically carry data between the central processing unit (CPU) and a memory controller hub, known as the northbridge.
Depending on the implementation, some computers may also have a back-side bus that connects the CPU to the cache. This bus and the cache connected to it are faster than accessing the system memory (or RAM) via the front-side bus. The speed of the front side bus is often used as an important measure of the performance of a computer.
The original front-side bus architecture has been replaced by HyperTransport, Intel QuickPath Interconnect or Direct Media Interface in modern CPUs in personal computers.
History
The term came into use by Intel Corporation about the time the Pentium Pro and Pentium II products were announced, in the 1990s.
"Front side" refers to the external interface from the processor to the rest of the computer system, as opposed to the back side, where the back-side bus connects the cache (and potentially other CPUs).
A front-side bus (FSB) is mostly used on PC-related motherboards (including personal computers and servers). They are seldom used in embedded systems or similar small computers. The FSB design was a performance improvement over the single system bus designs of the previous decades, but these front-side buses are sometimes referred to as the "system bus".
Front-side buses usually connect the CPU and the rest of the hardware via a chipset, which Intel implemented as a northbridge and a southbridge. Other buses like the Peripheral Component Interconnect (PCI), Accelerated Graphics Port (AGP), and memory buses all connect to the chipset in order for data to flow between the connected devices. These secondary system buses usually run at speeds derived from the front-side bus clock, but are not necessarily synch |
https://en.wikipedia.org/wiki/Satellite%20modem | A satellite modem or satmodem is a modem used to establish data transfers using a communications satellite as a relay. A satellite modem's main function is to transform an input bitstream to a radio signal and vice versa.
There are some devices that include only a demodulator (and no modulator, thus only allowing data to be downloaded by satellite) that are also referred to as "satellite modems." These devices are used in satellite Internet access (in this case uploaded data is transferred through a conventional PSTN modem or an ADSL modem).
Satellite link
A satellite modem is not the only device needed to establish a communication channel. Other equipment that is essential for creating a satellite link include satellite antennas and frequency converters.
Data to be transmitted are transferred to a modem from data terminal equipment (e.g. a computer). The modem usually has intermediate frequency (IF) output (that is, 50-200 MHz), however, sometimes the signal is modulated directly to L band. In most cases, frequency has to be converted using an upconverter before amplification and transmission.
A modulated signal is a sequence of symbols, pieces of data represented by a corresponding signal state, e.g. a bit or a few bits, depending upon the modulation scheme being used. Recovering a symbol clock (making a local symbol clock generator synchronous with the remote one) is one of the most important tasks of a demodulator.
Similarly, a signal received from a satellite is firstly downconverted (this is done by a Low-noise block converter - LNB), then demodulated by a modem, and at last handled by data terminal equipment. The LNB is usually powered by the modem through the signal cable with 13 or 18 V DC.
Features
The main functions of a satellite modem are modulation and demodulation. Satellite communication standards also define error correction codes and framing formats.
Popular modulation types being used for satellite communications:
Binary phase-shift k |
https://en.wikipedia.org/wiki/Exploratory%20engineering | Exploratory engineering is a term coined by K. Eric Drexler to describe the process of designing and analyzing detailed hypothetical models of systems that are not feasible with current technologies or methods, but do seem to be clearly within the bounds of what science considers to be possible within the narrowly defined scope of operation of the hypothetical system model. It usually results in paper or video prototypes, or (more likely nowadays) computer simulations that are as convincing as possible to those that know the relevant science, given the lack of experimental confirmation. By analogy with protoscience, it might be considered a form of protoengineering.
Usage
Due to the difficulty and necessity of anticipating results in such areas as genetic modification, climate change, molecular engineering, and megascale engineering, parallel fields such as bioethics, climate engineering and hypothetical molecular nanotechnology sometimes emerge to develop and examine hypotheses, define limits, and express potential solutions to the anticipated technological problems. Proponents of exploratory engineering contend that it is an appropriate initial approach to such problems.
Engineering is concerned with the design of a solution to a practical problem. A scientist may ask "why?" and proceed to research the answer to the question. By contrast, engineers want to know how to solve a problem, and how to implement that solution. Exploratory engineering often posits that a highly detailed solution exists, and explores the putative characteristics of such a solution, while holding in abeyance the question of how to implement that solution. If a point can be reached where the attempted implementation of the solution is addressed using the principles of engineering physics, the activity transitions from protoengineering to actual engineering, and results in success or failure to implement the design.
Requirements
Unlike the scientific method which relies on peer reviewed |
https://en.wikipedia.org/wiki/Universal%20Plug%20and%20Play | Universal Plug and Play (UPnP) is a set of networking protocols on the Internet Protocol (IP) that permits networked devices, such as personal computers, printers, Internet gateways, Wi-Fi access points and mobile devices, to seamlessly discover each other's presence on the network and establish functional network services. UPnP is intended primarily for residential networks without enterprise-class devices.
UPnP assumes the network runs IP and then leverages HTTP, on top of IP, in order to provide device/service description, actions, data transfer and event notification. Device search requests and advertisements are supported by running HTTP on top of UDP (port 1900) using multicast (known as HTTPMU). Responses to search requests are also sent over UDP, but are instead sent using unicast (known as HTTPU).
Conceptually, UPnP extends plug and play—a technology for dynamically attaching devices directly to a computer—to zero-configuration networking for residential and SOHO wireless networks. UPnP devices are plug and play in that, when connected to a network, they automatically establish working configurations with other devices, removing the need for users to manually configure and add devices through IP addresses.
UPnP is generally regarded as unsuitable for deployment in business settings for reasons of economy, complexity, and consistency: the multicast foundation makes it chatty, consuming too many network resources on networks with a large population of devices; the simplified access controls do not map well to complex environments; and it does not provide a uniform configuration syntax such as the CLI environments of Cisco IOS or JUNOS.
Overview
The UPnP architecture allows device-to-device networking of consumer electronics, mobile devices, personal computers, and networked home appliances. It is a distributed, open architecture protocol based on established standards such as the Internet Protocol Suite (TCP/IP), HTTP, XML, and SOAP. UPnP control points ( |
https://en.wikipedia.org/wiki/Proof%20theory | Proof theory is a major branch of mathematical logic and theoretical computer science within which proofs are treated as formal mathematical objects, facilitating their analysis by mathematical techniques. Proofs are typically presented as inductively-defined data structures such as lists, boxed lists, or trees, which are constructed according to the axioms and rules of inference of a given logical system. Consequently, proof theory is syntactic in nature, in contrast to model theory, which is semantic in nature.
Some of the major areas of proof theory include structural proof theory, ordinal analysis, provability logic, reverse mathematics, proof mining, automated theorem proving, and proof complexity. Much research also focuses on applications in computer science, linguistics, and philosophy.
History
Although the formalisation of logic was much advanced by the work of such figures as Gottlob Frege, Giuseppe Peano, Bertrand Russell, and Richard Dedekind, the story of modern proof theory is often seen as being established by David Hilbert, who initiated what is called Hilbert's program in the Foundations of Mathematics. The central idea of this program was that if we could give finitary proofs of consistency for all the sophisticated formal theories needed by mathematicians, then we could ground these theories by means of a metamathematical argument, which shows that all of their purely universal assertions (more technically their provable sentences) are finitarily true; once so grounded we do not care about the non-finitary meaning of their existential theorems, regarding these as pseudo-meaningful stipulations of the existence of ideal entities.
The failure of the program was induced by Kurt Gödel's incompleteness theorems, which showed that any ω-consistent theory that is sufficiently strong to express certain simple arithmetic truths, cannot prove its own consistency, which on Gödel's formulation is a sentence. However, modified versions of Hilbert's progr |
https://en.wikipedia.org/wiki/Metamathematics | Metamathematics is the study of mathematics itself using mathematical methods. This study produces metatheories, which are mathematical theories about other mathematical theories. Emphasis on metamathematics (and perhaps the creation of the term itself) owes itself to David Hilbert's attempt to secure the foundations of mathematics in the early part of the 20th century. Metamathematics provides "a rigorous mathematical technique for investigating a great variety of foundation problems for mathematics and logic" (Kleene 1952, p. 59). An important feature of metamathematics is its emphasis on differentiating between reasoning from inside a system and from outside a system. An informal illustration of this is categorizing the proposition "2+2=4" as belonging to mathematics while categorizing the proposition "'2+2=4' is valid" as belonging to metamathematics.
History
Metamathematical metatheorems about mathematics itself were originally differentiated from ordinary mathematical theorems in the 19th century to focus on what was then called the foundational crisis of mathematics. Richard's paradox (Richard 1905) concerning certain 'definitions' of real numbers in the English language is an example of the sort of contradictions that can easily occur if one fails to distinguish between mathematics and metamathematics. Something similar can be said around the well-known Russell's paradox (Does the set of all those sets that do not contain themselves contain itself?).
Metamathematics was intimately connected to mathematical logic, so that the early histories of the two fields, during the late 19th and early 20th centuries, largely overlap. More recently, mathematical logic has often included the study of new pure mathematics, such as set theory, category theory, recursion theory and pure model theory, which is not directly related to metamathematics.
Serious metamathematical reflection began with the work of Gottlob Frege, especially his Begriffsschrift, published in 1879 |
https://en.wikipedia.org/wiki/Allan%20Hills%2084001 | Allan Hills 84001 (ALH84001) is a fragment of a Martian meteorite that was found in the Allan Hills in Antarctica on December 27, 1984, by a team of American meteorite hunters from the ANSMET project. Like other members of the shergottite–nakhlite–chassignite (SNC) group of meteorites, ALH84001 is thought to have originated on Mars. However, it does not fit into any of the previously discovered SNC groups. Its mass upon discovery was .
In 1996, a group of scientists found features in the likeness of microscopic fossils of bacteria in the meteorite, suggesting that these organisms also originated on Mars. The claims immediately made headlines worldwide, culminating in U.S. president Bill Clinton giving a speech about the potential discovery. These claims were controversial from the beginning, and the wider scientific community ultimately rejected the hypothesis once all the unusual features in the meteorite had been explained without requiring life to be present. Despite there being no convincing evidence of Martian life, the initial paper and the enormous scientific and public attention caused by it are considered turning points in the history of the developing science of astrobiology.
History and description
ALH 84001 was found on the Allan Hills Far Western Icefield during the 1984–85 season, by Roberta Score, Lab Manager of the Antarctic Meteorite Laboratory at the Johnson Space Center.
ALH84001 is thought to be one of the oldest Martian meteorites, proposed to have crystallized from molten rock 4.091 billion years ago. Chemical analysis suggests that it originated on Mars when there was liquid water on the planet's surface.
In September 2005, Vicky Hamilton, of the University of Hawaii at Manoa, presented an analysis of the origin of ALH84001 using data from the Mars Global Surveyor and 2001 Mars Odyssey spacecraft orbiting Mars. According to the analysis, Eos Chasma in the Valles Marineris canyon appears to be the source of the meteorite. The analysis was |
https://en.wikipedia.org/wiki/Steve%20Jones%20%28biologist%29 | John Stephen Jones DSC FLSW (born 24 March 1944) is a British geneticist and from 1995 to 1999 and 2008 to June 2010 was Head of the Department of Genetics, Evolution and Environment at University College London. His studies are conducted in the Galton Laboratory.
He is also a television presenter and a prize-winning author on the subject of biology, especially evolution. He is a popular contemporary writer on evolution. In 1996 his work won him the Michael Faraday Prize "for his numerous, wide ranging contributions to the public understanding of science in areas such as human evolution and variation, race, sex, inherited disease and genetic manipulation through his many broadcasts on radio and television, his lectures, popular science books, and his once-regular science column in The Daily Telegraph and contributions to other newspaper media".
Early life and education
Jones was born in Aberystwyth, Wales, to Lydia Anne and Thomas Gwilym Jones. His parents met as students at the University of Aberystwyth. Until he was about ten years old the family lived alternately at his paternal grandparents' house in New Quay, Ceredigion, and his maternal grandparents' house near Aberystwyth. Later the family moved to the Wirral, returning to Wales for their holidays.
Jones's paternal grandfather and great grandfather were both sea captains. Jones' father, a PhD chemist, worked on detergents such as Jif. Dylan Thomas was an acquaintance of his father. As a child Jones often stayed at his paternal grandparents' home and spent a lot of his time in the attic which contained some seafaring equipment, and boxes of books covering a wide variety of topics, many of which Jones read. He also went to libraries and by the age of 14 years he had read all the works of Charles Dickens.
As a child in Ceredigion Jones spoke a lot of Welsh until he was 6 or 7 years old, and as a keen observer of local wildlife was particularly interested in birds. Jones was a pupil at Wirral Grammar School |
https://en.wikipedia.org/wiki/Coccidioidomycosis | Coccidioidomycosis (, ), commonly known as cocci, Valley fever, as well as California fever, desert rheumatism, or San Joaquin Valley fever, is a mammalian fungal disease caused by Coccidioides immitis or Coccidioides posadasii. Coccidioidomycosis is endemic in certain parts of the United States in Arizona, California, Nevada, New Mexico, Texas, Utah, and northern Mexico.
C. immitis is a dimorphic saprophytic fungus that grows as a mycelium in the soil and produces a spherule form in the host organism. C. immitis is dormant during long dry spells, then develops as a mold with long filaments that break off into airborne spores when it rains.
Coccidioidomycosis is a common cause of community-acquired pneumonia in the endemic areas of the United States. Infections usually occur due to inhalation of the arthroconidial spores after soil disruption. The disease is not contagious. In some cases the infection may recur or become chronic.
Description
Coccidioidomycosis is a mammalian fungal disease caused by Coccidioides immitis or Coccidioides posadasii. It is commonly known as cocci, Valley fever, as well as California fever, desert rheumatism, or San Joaquin Valley fever. Coccidioidomycosis is endemic in certain parts of the United States in Arizona, California, Nevada, New Mexico, Texas, Utah, and northern Mexico.
C. immitis is a dimorphic saprophytic fungus that grows as a mycelium in the soil and produces a spherule form in the host organism. It resides in the soil in certain parts of the southwestern United States, most notably in California and Arizona. It is also commonly found in northern Mexico, and parts of Central and South America. C. immitis is dormant during long dry spells, then develops as a mold with long filaments that break off into airborne spores when it rains. The spores, known as arthroconidia, are swept into the air by disruption of the soil, such as during construction, farming, low-wind or singular dust events, or an earthquake. Windstorms m |
https://en.wikipedia.org/wiki/UTF-32 | UTF-32 (32-bit Unicode Transformation Format) is a fixed-length encoding used to encode Unicode code points that uses exactly 32 bits (four bytes) per code point (but a number of leading bits must be zero as there are far fewer than 232 Unicode code points, needing actually only 21 bits). UTF-32 is a fixed-length encoding, in contrast to all other Unicode transformation formats, which are variable-length encodings. Each 32-bit value in UTF-32 represents one Unicode code point and is exactly equal to that code point's numerical value.
The main advantage of UTF-32 is that the Unicode code points are directly indexed. Finding the Nth code point in a sequence of code points is a constant-time operation. In contrast, a variable-length code requires linear-time to count N code points from the start of the string. This makes UTF-32 a simple replacement in code that uses integers that are incremented by one to examine each location in a string, as was commonly done for ASCII. However, Unicode code points are rarely processed in complete isolation, such as combining character sequences and for emoji.
The main disadvantage of UTF-32 is that it is space-inefficient, using four bytes per code point, including 11 bits that are always zero. Characters beyond the BMP are relatively rare in most texts (except for e.g. texts with some popular emojis), and can typically be ignored for sizing estimates. This makes UTF-32 close to twice the size of UTF-16. It can be up to four times the size of UTF-8 depending on how many of the characters are in the ASCII subset.
History
The original ISO/IEC 10646 standard defines a 32-bit encoding form called UCS-4, in which each code point in the Universal Character Set (UCS) is represented by a 31-bit value from 0 to 0x7FFFFFFF (the sign bit was unused and zero). In November 2003, Unicode was restricted by RFC 3629 to match the constraints of the UTF-16 encoding: explicitly prohibiting code points greater than U+10FFFF (and also the high and lo |
https://en.wikipedia.org/wiki/Infinitesimal%20strain%20theory | In continuum mechanics, the infinitesimal strain theory is a mathematical approach to the description of the deformation of a solid body in which the displacements of the material particles are assumed to be much smaller (indeed, infinitesimally smaller) than any relevant dimension of the body; so that its geometry and the constitutive properties of the material (such as density and stiffness) at each point of space can be assumed to be unchanged by the deformation.
With this assumption, the equations of continuum mechanics are considerably simplified. This approach may also be called small deformation theory, small displacement theory, or small displacement-gradient theory. It is contrasted with the finite strain theory where the opposite assumption is made.
The infinitesimal strain theory is commonly adopted in civil and mechanical engineering for the stress analysis of structures built from relatively stiff elastic materials like concrete and steel, since a common goal in the design of such structures is to minimize their deformation under typical loads. However, this approximation demands caution in the case of thin flexible bodies, such as rods, plates, and shells which are susceptible to significant rotations, thus making the results unreliable.
Infinitesimal strain tensor
For infinitesimal deformations of a continuum body, in which the displacement gradient tensor (2nd order tensor) is small compared to unity, i.e. ,
it is possible to perform a geometric linearization of any one of the (infinitely many possible) finite strain tensors used in finite strain theory, e.g. the Lagrangian finite strain tensor , and the Eulerian finite strain tensor . In such a linearization, the non-linear or second-order terms of the finite strain tensor are neglected. Thus we have
or
and
or
This linearization implies that the Lagrangian description and the Eulerian description are approximately the same as there is little difference in the material and spatial coordi |
https://en.wikipedia.org/wiki/JBuilder | JBuilder is a discontinued integrated development environment (IDE) for the programming language Java from Embarcadero Technologies. Originally developed by Borland, JBuilder was spun off with CodeGear which was eventually purchased by Embarcadero Technologies in 2008.
Oracle had based the first versions of JDeveloper on code from JBuilder licensed from Borland, but it has since been rewritten from scratch.
Versions
JBuilder 1 through 3 are based on the Delphi IDE. JBuilder 3.5 through 2006 are based on PrimeTime, an all-Java IDE framework. JBuilder 2007 "Peloton" is the first JBuilder release based on the eclipse IDE framework.
See also
Comparison of integrated development environments
References
External links
History of some JBuilder versions
CodeGear software
Java development tools
Integrated development environments
Cross-platform software |
https://en.wikipedia.org/wiki/Time%20hierarchy%20theorem | In computational complexity theory, the time hierarchy theorems are important statements about time-bounded computation on Turing machines. Informally, these theorems say that given more time, a Turing machine can solve more problems. For example, there are problems that can be solved with n2 time but not n time.
The time hierarchy theorem for deterministic multi-tape Turing machines was first proven by Richard E. Stearns and Juris Hartmanis in 1965. It was improved a year later when F. C. Hennie and Richard E. Stearns improved the efficiency of the Universal Turing machine. Consequent to the theorem, for every deterministic time-bounded complexity class, there is a strictly larger time-bounded complexity class, and so the time-bounded hierarchy of complexity classes does not completely collapse. More precisely, the time hierarchy theorem for deterministic Turing machines states that for all time-constructible functions f(n),
,
where DTIME(f(n)) denotes the complexity class of decision problems solvable in time O(f(n)). Note that the left-hand class involves little o notation, referring to the set of decision problems solvable in asymptotically less than f(n) time.
The time hierarchy theorem for nondeterministic Turing machines was originally proven by Stephen Cook in 1972. It was improved to its current form via a complex proof by Joel Seiferas, Michael Fischer, and Albert Meyer in 1978. Finally in 1983, Stanislav Žák achieved the same result with the simple proof taught today. The time hierarchy theorem for nondeterministic Turing machines states that if g(n) is a time-constructible function, and f(n+1) = o(g(n)), then
.
The analogous theorems for space are the space hierarchy theorems. A similar theorem is not known for time-bounded probabilistic complexity classes, unless the class also has one bit of advice.
Background
Both theorems use the notion of a time-constructible function. A function is time-constructible if there exists a deterministic Turing mac |
https://en.wikipedia.org/wiki/Perovskite%20%28structure%29 | A perovskite is any material with a crystal structure following the formula ABX3, which was first discovered as the mineral called perovskite, which consists of calcium titanium oxide (CaTiO3). The mineral was first discovered in the Ural mountains of Russia by Gustav Rose in 1839 and named after Russian mineralogist L. A. Perovski (1792–1856). 'A' and 'B' are two positively charged ions (i.e. cations), often of very different sizes, and X is a negatively charged ion (an anion, frequently oxide) that bonds to both cations. The 'A' atoms are generally larger than the 'B' atoms. The ideal cubic structure has the B cation in 6-fold coordination, surrounded by an octahedron of anions, and the A cation in 12-fold cuboctahedral coordination. Additional perovskite forms may exist where either/both the A and B sites have a configuration of A1x-1A2x and/or B1y-1B2y and the X may deviate from the ideal coordination configuration as ions within the A and B sites undergo changes in their oxidation states.
As one of the most abundant structural families, perovskites are found in an enormous number of compounds which have wide-ranging properties, applications and importance. Natural compounds with this structure are perovskite, loparite, and the silicate perovskite bridgmanite. Since the 2009 discovery of perovskite solar cells, which contain methylammonium lead halide perovskites, there has been considerable research interest into perovskite materials.
Structure
Perovskite structures are adopted by many oxides that have the chemical formula ABO3. The idealized form is a cubic structure (space group Pmm, no. 221) which is rarely encountered. The orthorhombic (e.g. space group Pnma, no. 62, or Amm2, no. 68) and tetragonal (e.g. space group I4/mcm, no. 140, or P4mm, no. 99) phases are the most common non-cubic variants. Although the perovskite structure is named after CaTiO3, this mineral forms a non-idealized form. SrTiO3 and CaRbF3 are examples of cubic perovskites. Barium tita |
https://en.wikipedia.org/wiki/FOXP2 | Forkhead box protein P2 (FOXP2) is a protein that, in humans, is encoded by the FOXP2 gene. FOXP2 is a member of the forkhead box family of transcription factors, proteins that regulate gene expression by binding to DNA. It is expressed in the brain, heart, lungs and digestive system.
FOXP2 is found in many vertebrates, where it plays an important role in mimicry in birds (such as birdsong) and echolocation in bats. FOXP2 is also required for the proper development of speech and language in humans. In humans, mutations in FOXP2 cause the severe speech and language disorder developmental verbal dyspraxia. Studies of the gene in mice and songbirds indicate that it is necessary for vocal imitation and the related motor learning. Outside the brain, FOXP2 has also been implicated in development of other tissues such as the lung and digestive system.
Initially identified in 1998 as the genetic cause of a speech disorder in a British family designated the KE family, FOXP2 was the first gene discovered to be associated with speech and language and was subsequently dubbed "the language gene". However, other genes are necessary for human language development, and a 2018 analysis confirmed that there was no evidence of recent positive evolutionary selection of FOXP2 in humans.
Structure and function
As a FOX protein, FOXP2 contains a forkhead-box domain. In addition, it contains a polyglutamine tract, a zinc finger and a leucine zipper. The protein attaches to the DNA of other proteins and controls their activity through the forkhead-box domain. Only a few targeted genes have been identified, however researchers believe that there could be up to hundreds of other genes targeted by the FOXP2 gene. The forkhead box P2 protein is active in the brain and other tissues before and after birth, many studies show that it is paramount for the growth of nerve cells and transmission between them. The FOXP2 gene is also involved in synaptic plasticity, making it imperative for learni |
https://en.wikipedia.org/wiki/Danny%20Carey | Daniel Edwin Carey (born May 10, 1961) is an American musician and songwriter. He is the drummer for the American rock band Tool. He has also contributed to albums by artists such as Zaum, Green Jellö, Pigface, Skinny Puppy, Adrian Belew, Carole King, Collide, Meat Puppets, Lusk, and the Melvins.
He was ranked among the 100 greatest drummers of all time by Rolling Stone magazine, occupying the 26th position, in addition to being frequently considered by other magazines.
Biography
Born in Lawrence, Kansas, Carey's first encounter with the drums began at the age of ten by joining the school band and taking private lessons on the snare drum. Two years later, Carey began to practice on a drum set. In his senior year of high school in Paola, Kansas, Carey joined the high school jazz band. Carey also played basketball. Jazz would later play a huge role in his signature approach to the drum set in a rock setting. As Carey progressed through high school and later college at the University of Missouri–Kansas City, he began expanding his studies in percussion with theory into the principles of geometry, science, and metaphysics as well as delving into the occult. Carey also played jazz while attending college and got to experience the jazz scene in Kansas City.
After college, a friend and bandmate convinced Carey to leave Kansas for Portland, Oregon, where he played briefly in various bands before moving to Los Angeles, where he was able to perform as a studio drummer with Carole King and perform live sets with Pigmy Love Circus. He also played in Green Jellö as "Danny Longlegs" and recorded the album Cereal Killer. He would later find his way to Tool after coming to know singer Maynard James Keenan and guitarist Adam Jones and practicing with them in place of drummers the two had requested but had never shown up. Besides Tool, Carey also finds time for other projects new and old such as Legend of the Seagullmen, Pigmy Love Circus, Volto!, and Zaum.
Carey's drumming infl |
https://en.wikipedia.org/wiki/Chebyshev%20polynomials | The Chebyshev polynomials are two sequences of polynomials related to the cosine and sine functions, notated as and . They can be defined in several equivalent ways, one of which starts with trigonometric functions:
The Chebyshev polynomials of the first kind are defined by:
Similarly, the Chebyshev polynomials of the second kind are defined by:
That these expressions define polynomials in may not be obvious at first sight but follows by rewriting and using de Moivre's formula or by using the angle sum formulas for and repeatedly. For example, the double angle formulas, which follow directly from the angle sum formulas, may be used to obtain and , which are respectively a polynomial in and a polynomial in multiplied by . Hence and .
An important and convenient property of the is that they are orthogonal with respect to the inner product:
and are orthogonal with respect to another, analogous inner product, given below.
The Chebyshev polynomials are polynomials with the largest possible leading coefficient whose absolute value on the interval is bounded by 1. They are also the "extremal" polynomials for many other properties.
In 1952, Cornelius Lanczos showed that the Chebyshev polynomials are important in approximation theory for the solution of linear systems; the roots of , which are also called Chebyshev nodes, are used as matching points for optimizing polynomial interpolation. The resulting interpolation polynomial minimizes the problem of Runge's phenomenon and provides an approximation that is close to the best polynomial approximation to a continuous function under the maximum norm, also called the "minimax" criterion. This approximation leads directly to the method of Clenshaw–Curtis quadrature.
These polynomials were named after Pafnuty Chebyshev. The letter is used because of the alternative transliterations of the name Chebyshev as , (French) or (German).
Definitions
Recurrence definition
The Chebyshev polynomials of t |
https://en.wikipedia.org/wiki/SBus | SBus is a computer bus system that was used in most SPARC-based computers (including all SPARCstations) from Sun Microsystems and others during the 1990s. It was introduced by Sun in 1989 to be a high-speed bus counterpart to their high-speed SPARC processors, replacing the earlier (and by this time, outdated) VMEbus used in their Motorola 68020- and 68030-based systems and early SPARC boxes. When Sun moved to open the SPARC definition in the early 1990s, SBus was likewise standardized and became IEEE-1496. In 1997 Sun started to migrate away from SBus to the Peripheral Component Interconnect (PCI) bus, and today SBus is no longer used.
The industry's first third-party SBus cards were announced in 1989 by Antares Microsystems; these were a 10BASE2 Ethernet controller, a SCSI-SNS host adapter, a parallel port, and an 8-channel serial controller.
The specification was published by Edward H. Frank and James D. Lyle.
A technical guide to the bus was published in 1992 in book form by Lyle, who founded Troubador Technologies. Sun also published a set of books as a "developer's kit" to encourage third-party products.
At the peak of the market over 250 manufacturers were listed in the SBus Product Directory, which was renamed to the SPARC Product Directory in 1996.
SBus is in many ways a "clean" design. It was targeted only to be used with SPARC processors, so most cross-platform issues were not a consideration. SBus is based on a big-endian 32-bit address and data bus, can run at speeds ranging from 16.67 MHz to 25 MHz, and is capable of transferring up to 100 MB/s. Devices are each mapped onto a 28-bit address space (256 MB). Only eight masters are supported, although there can be an unlimited number of slaves.
When the 64-bit UltraSPARC was introduced, SBus was modified to support extended transfers of a 64 bits doubleword per cycle to produce a 200 MB/s 64-bit bus. This variant of the SBus architecture used the same form factor and was backward-compatible with exis |
https://en.wikipedia.org/wiki/PIC%20microcontrollers | PIC (usually pronounced as [pʰɪk]) is a family of microcontrollers made by Microchip Technology, derived from the PIC1650 originally developed by General Instrument's Microelectronics Division. The name PIC initially referred to Peripheral Interface Controller, and is currently expanded as Programmable Intelligent Computer.
The first parts of the family were available in 1976; by 2013 the company had shipped more than twelve billion individual parts, used in a wide variety of embedded systems.
The PIC was originally intended to be used with the General Instrument CP1600, the first commercially available single-chip 16-bit microprocessor. The CP1600 had a complex bus that made it difficult to interface with, and the PIC was introduced as a companion device offering ROM for program storage, RAM for temporary data handling, and a simple CPU for controlling the transfers. While this offered considerable power, GI's marketing was limited and the CP1600 was not a success. When the company spun off their chip division to form Microchip in 1985, sales of the CP1600 were all but dead. By this time, the PIC had formed a major market of its own, and it became one of the new company's primary products.
Early models only had mask ROM for code storage, but with its spinoff it was soon upgraded to use EPROM and then EEPROM, which made it possible for end-users to program the devices in their own facilities. All current models use flash memory for program storage, and newer models allow the PIC to reprogram itself. Since then the line has seen significant change; memory is now available in 8-bit, 16-bit, and, in latest models, 32-bit wide. Program instructions vary in bit-count by family of PIC, and may be 12, 14, 16, or 24 bits long. The instruction set also varies by model, with more powerful chips adding instructions for digital signal processing functions. The hardware implementations of PIC devices range from 6-pin SMD, 8-pin DIP chips up to 144-pin SMD chips, with discrete |
https://en.wikipedia.org/wiki/Quotient%20ring | In ring theory, a branch of abstract algebra, a quotient ring, also known as factor ring, difference ring or residue class ring, is a construction quite similar to the quotient group in group theory and to the quotient space in linear algebra. It is a specific example of a quotient, as viewed from the general setting of universal algebra. Starting with a ring and a two-sided ideal in , a new ring, the quotient ring , is constructed, whose elements are the cosets of in subject to special and operations. (Only the fraction slash "/" is used in quotient ring notation, not a horizontal fraction bar.)
Quotient rings are distinct from the so-called "quotient field", or field of fractions, of an integral domain as well as from the more general "rings of quotients" obtained by localization.
Formal quotient ring construction
Given a ring and a two-sided ideal in , we may define an equivalence relation on as follows:
if and only if is in .
Using the ideal properties, it is not difficult to check that is a congruence relation.
In case , we say that and are congruent modulo .
The equivalence class of the element in is given by
.
This equivalence class is also sometimes written as and called the "residue class of modulo ".
The set of all such equivalence classes is denoted by ; it becomes a ring, the factor ring or quotient ring of modulo , if one defines
;
.
(Here one has to check that these definitions are well-defined. Compare coset and quotient group.) The zero-element of is , and the multiplicative identity is .
The map from to defined by is a surjective ring homomorphism, sometimes called the natural quotient map or the canonical homomorphism.
Examples
The quotient ring } is naturally isomorphic to R, and is the zero ring {0}, since, by our definition, for any r in R, we have that }}, which equals R itself. This fits with the rule of thumb that the larger the ideal I, the smaller the quotient ring . If I is a proper ideal of R, i.e., , t |
https://en.wikipedia.org/wiki/Heat%20transfer | Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy (heat) between physical systems. Heat transfer is classified into various mechanisms, such as thermal conduction, thermal convection, thermal radiation, and transfer of energy by phase changes. Engineers also consider the transfer of mass of differing chemical species (mass transfer in the form of advection), either cold or hot, to achieve heat transfer. While these mechanisms have distinct characteristics, they often occur simultaneously in the same system.
Heat conduction, also called diffusion, is the direct microscopic exchanges of kinetic energy of particles (such as molecules) or quasiparticles (such as lattice waves) through the boundary between two systems. When an object is at a different temperature from another body or its surroundings, heat flows so that the body and the surroundings reach the same temperature, at which point they are in thermal equilibrium. Such spontaneous heat transfer always occurs from a region of high temperature to another region of lower temperature, as described in the second law of thermodynamics.
Heat convection occurs when the bulk flow of a fluid (gas or liquid) carries its heat through the fluid. All convective processes also move heat partly by diffusion, as well. The flow of fluid may be forced by external processes, or sometimes (in gravitational fields) by buoyancy forces caused when thermal energy expands the fluid (for example in a fire plume), thus influencing its own transfer. The latter process is often called "natural convection". The former process is often called "forced convection." In this case, the fluid is forced to flow by use of a pump, fan, or other mechanical means.
Thermal radiation occurs through a vacuum or any transparent medium (solid or fluid or gas). It is the transfer of energy by means of photons or electromagnetic waves governed by the same laws.
Overview
Heat |
https://en.wikipedia.org/wiki/Tempest%20%28codename%29 | TEMPEST is a U.S. National Security Agency specification and a NATO certification referring to spying on information systems through leaking emanations, including unintentional radio or electrical signals, sounds, and vibrations. TEMPEST covers both methods to spy upon others and how to shield equipment against such spying. The protection efforts are also known as emission security (EMSEC), which is a subset of communications security (COMSEC).
The NSA methods for spying on computer emissions are classified, but some of the protection standards have been released by either the NSA or the Department of Defense. Protecting equipment from spying is done with distance, shielding, filtering, and masking. The TEMPEST standards mandate elements such as equipment distance from walls, amount of shielding in buildings and equipment, and distance separating wires carrying classified vs. unclassified materials, filters on cables, and even distance and shielding between wires or equipment and building pipes. Noise can also protect information by masking the actual data.
While much of TEMPEST is about leaking electromagnetic emanations, it also encompasses sounds and mechanical vibrations. For example, it is possible to log a user's keystrokes using the motion sensor inside smartphones. Compromising emissions are defined as unintentional intelligence-bearing signals which, if intercepted and analyzed (side-channel attack), may disclose the information transmitted, received, handled, or otherwise processed by any information-processing equipment.
History
During World War II, Bell Telephone supplied the U.S. military with the 131-B2 mixer device that encrypted teleprinter signals by XOR’ing them with key material from one-time tapes (the SIGTOT system) or, earlier, a rotor-based key generator called SIGCUM. It used electromechanical relays in its operation. Later, Bell informed the Signal Corps that they were able to detect electromagnetic spikes at a distance from the mixer and |
https://en.wikipedia.org/wiki/Simple%20Service%20Discovery%20Protocol | The Simple Service Discovery Protocol (SSDP) is a network protocol based on the Internet protocol suite for advertisement and discovery of network services and presence information. It accomplishes this without assistance of server-based configuration mechanisms, such as Dynamic Host Configuration Protocol (DHCP) or Domain Name System (DNS), and without special static configuration of a network host. SSDP is the basis of the discovery protocol of Universal Plug and Play (UPnP) and is intended for use in residential or small office environments. It was formally described in an IETF Internet Draft by Microsoft and Hewlett-Packard in 1999. Although the IETF proposal has since expired (April, 2000), SSDP was incorporated into the UPnP protocol stack, and a description of the final implementation is included in UPnP standards documents.
Protocol transport and addressing
SSDP is a text-based protocol based on HTTPU, which uses UDP as the underlying transport protocol. Services are announced by the hosting system with multicast addressing to a specifically designated IP multicast address at UDP port number 1900. In IPv4, the multicast address is and SSDP over IPv6 uses the address set for all scope ranges indicated by X.
This results in the following well-known practical multicast addresses for SSDP:
(IPv4 site-local address)
(IPv6 link-local)
(IPv6 site-local)
Additionally, applications may use the source-specific multicast addresses derived from the local IPv6 routing prefix, with group ID C (decimal 12).
SSDP uses the HTTP method NOTIFY to announce the establishment or withdrawal of services (presence) information to the multicast group. A client that wishes to discover available services on a network, uses method M-SEARCH. Responses to such search requests are sent via unicast addressing to the originating address and port number of the multicast request.
Microsoft's IPv6 SSDP implementations in Windows Media Player and Server use the link-local scope addr |
https://en.wikipedia.org/wiki/Internet%20Architecture%20Board | The Internet Architecture Board (IAB) is "a committee of the Internet Engineering Task Force (IETF) and an advisory body of the Internet Society (ISOC). Its responsibilities include architectural oversight of IETF activities, Internet Standards Process oversight and appeal, and the appointment of the Request for Comments (RFC) Editor. The IAB is also responsible for the management of the IETF protocol parameter registries."
The IAB is responsible for:
Providing architectural oversight of Internet protocols and procedures
Liaising with other organizations on behalf of the Internet Engineering Task Force (IETF)
Reviewing appeals of the Internet standards process
Managing Internet standards documents (the RFC series) and protocol parameter value assignment
Confirming the Chair of the IETF and the IETF Area Directors
Selecting the Internet Research Task Force (IRTF) Chair
Acting as a source of advice and guidance to the Internet Society.
In its work, the IAB strives to:
Ensure that the Internet is a trusted medium of communication that provides a solid technical foundation for privacy and security, especially in light of pervasive surveillance,
Establish the technical direction for an Internet that will enable billions more people to connect, support the vision for an Internet of things, and allow mobile networks to flourish, while keeping the core capabilities that have been a foundation of the Internet's success, and
Promote the technical evolution of an open Internet without special controls, especially those which hinder trust in the network.
History and Origin
The body which eventually became the IAB was created originally by the United States Department of Defense's Defense Advanced Research Projects Agency with the name Internet Configuration Control Board (ICCB) in 1979. Later, in 1983, the ICCB was reorganized by Barry Leiner, Vint Cerf's successor at DARPA, around a series of task forces considering different technical aspects of internetting. The re-o |
https://en.wikipedia.org/wiki/Internet%20Research%20Task%20Force | The Internet Research Task Force (IRTF) is an organization, overseen by the Internet Architecture Board, that focuses on longer-term research issues related to the Internet. A parallel organization, the Internet Engineering Task Force (IETF), focuses on the shorter term issues of engineering and standards making.
The IRTF promotes research of importance to the evolution of the Internet by creating focused, long-term research groups working on topics related to Internet protocols, applications, architecture and technology. Unlike the IETF, the task force does not set standards and there is no explicit outcome expected of IRTF research groups.
Organization
The IRTF is composed of a number of focused and long-term research groups. These groups work on topics related to Internet protocols, applications, architecture and technology. Research groups have the stable long-term membership needed to promote the development of research collaboration and teamwork in exploring research issues. Participation is by individual contributors, rather than by representatives of organizations. The list of current groups can be found on the IRTF's homepage.
Operations
The IRTF is managed by the IRTF chair in consultation with the Internet Research Steering Group (IRSG). The IRSG membership includes the IRTF chair, the chairs of the various Research Groups and other individuals (members at large) from the research community selected by the IRTF chair. The chair of the IRTF is appointed by the Internet Architecture Board (IAB) for a two-year term.
These individuals have chaired the IRTF:
David D. Clark, 1989–1992
Jon Postel, 1992–1995
Abel Weinrib, 1995–1999
Erik Huizer, 1999–2001
Vern Paxson, 2001–2005
Aaron Falk, 2005–2011
Lars Eggert, 2011–2017
Allison Mankin, 2017–2019
Colin Perkins, 2019–Present
The IRTF chair is responsible for ensuring that research groups produce coherent, coordinated, architecturally consistent and timely output as a contribution to the overall |
https://en.wikipedia.org/wiki/Reagent | In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms reactant and reagent are often used interchangeably, but reactant specifies a substance consumed in the course of a chemical reaction. Solvents, though involved in the reaction mechanism, are usually not called reactants. Similarly, catalysts are not consumed by the reaction, so they are not reactants. In biochemistry, especially in connection with enzyme-catalyzed reactions, the reactants are commonly called substrates.
Definitions
Organic chemistry
In organic chemistry, the term "reagent" denotes a chemical ingredient (a compound or mixture, typically of inorganic or small organic molecules) introduced to cause the desired transformation of an organic substance. Examples include the Collins reagent, Fenton's reagent, and Grignard reagents.
Analytical chemistry
In analytical chemistry, a reagent is a compound or mixture used to detect the presence or absence of another substance, e.g. by a color change, or to measure the concentration of a substance, e.g. by colorimetry. Examples include Fehling's reagent, Millon's reagent, and Tollens' reagent.
Commercial or laboratory preparations
In commercial or laboratory preparations, reagent-grade designates chemical substances meeting standards of purity that ensure the scientific precision and reliability of chemical analysis, chemical reactions or physical testing. Purity standards for reagents are set by organizations such as ASTM International or the American Chemical Society. For instance, reagent-quality water must have very low levels of impurities such as sodium and chloride ions, silica, and bacteria, as well as a very high electrical resistivity. Laboratory products which are less pure, but still useful and economical for undemanding work, may be designated as technical, practical, or crude grade to distinguish them from reagent versions.
Biology
In t |
https://en.wikipedia.org/wiki/Ramsey%27s%20theorem | In combinatorics, Ramsey's theorem, in one of its graph-theoretic forms, states that one will find monochromatic cliques in any edge labelling (with colours) of a sufficiently large complete graph. To demonstrate the theorem for two colours (say, blue and red), let and be any two positive integers. Ramsey's theorem states that there exists a least positive integer for which every blue-red edge colouring of the complete graph on vertices contains a blue clique on vertices or a red clique on vertices. (Here signifies an integer that depends on both and .)
Ramsey's theorem is a foundational result in combinatorics. The first version of this result was proved by Frank Ramsey. This initiated the combinatorial theory now called Ramsey theory, that seeks regularity amid disorder: general conditions for the existence of substructures with regular properties. In this application it is a question of the existence of monochromatic subsets, that is, subsets of connected edges of just one colour.
An extension of this theorem applies to any finite number of colours, rather than just two. More precisely, the theorem states that for any given number of colours, , and any given integers , there is a number, , such that if the edges of a complete graph of order are coloured with different colours, then for some between 1 and , it must contain a complete subgraph of order whose edges are all colour . The special case above has (and and ).
Examples
R(3, 3) = 6
Suppose the edges of a complete graph on 6 vertices are coloured red and blue. Pick a vertex, . There are 5 edges incident to and so (by the pigeonhole principle) at least 3 of them must be the same colour. Without loss of generality we can assume at least 3 of these edges, connecting the vertex, , to vertices, , and , are blue. (If not, exchange red and blue in what follows.) If any of the edges, , , , are also blue then we have an entirely blue triangle. If not, then those three edges are all red and we hav |
https://en.wikipedia.org/wiki/Home%20automation | Home automation or domotics is building automation for a home. A home automation system will monitor and/or control home attributes such as lighting, climate, entertainment systems, and appliances. It may also include home security such as access control and alarm systems.
The phrase smart home refers to home automation devices that have internet access. Home automation, a broader category, includes any device that can be monitored or controlled via wireless radio signals, not just those having internet access. When connected with the Internet, home sensors and activation devices are an important constituent of the Internet of Things ("IoT").
A home automation system typically connects controlled devices to a central smart home hub (sometimes called a "gateway"). The user interface for control of the system uses either wall-mounted terminals, tablet or desktop computers, a mobile phone application, or a Web interface that may also be accessible off-site through the Internet.
History
Early home automation began with labor-saving machines. Self-contained electric or gas powered home appliances became viable in the 1900s with the introduction of electric power distribution and led to the introduction of washing machines (1904), water heaters (1889), refrigerators (1913), sewing machines, dishwashers, and clothes dryers.
In 1975, the first general purpose home automation network technology, X10, was developed. It is a communication protocol for electronic devices. It primarily uses electric power transmission wiring for signalling and control, where the signals involve brief radio frequency bursts of digital data, and remains the most widely available.
By 2012, in the United States, according to ABI Research, 1.5 million home automation systems were installed.
Per research firm Statista more than 45 million smart home devices will be installed in U.S. homes by the end of the year 2018.
The word "domotics" is a contraction of the Latin word for a home (domus) a |
https://en.wikipedia.org/wiki/MSN | MSN (meaning Microsoft Network) is a web portal and related collection of Internet services and apps for Windows and mobile devices, provided by Microsoft and launched on August 24, 1995, alongside the release of Windows 95.
The Microsoft Network was initially a subscription-based dial-up online service that later became an Internet service provider named MSN Dial-up. At the same time, the company launched a new web portal named Microsoft Internet Start and set it as the first default home page of Internet Explorer, its web browser. In 1998, Microsoft renamed and moved this web portal to the domain name www.msn.com, where it has remained.
In addition to its original MSN Dial-up service, Microsoft has used the 'MSN' brand name for a wide variety of products and services over the years, notably Hotmail (later Outlook.com), Messenger (which was once synonymous with 'MSN' in Internet slang and has now been replaced by Skype), and its web search engine, which is now Bing, and several other rebranded and discontinued services.
The current website and suite of apps offered by MSN was first introduced by Microsoft in 2014 as part of a complete redesign and relaunch. MSN is based in the United States and offers international versions of its portal for dozens of countries around the world.
History
Microsoft Internet Start
From 1995 to 1998, the MSN.com domain was used by Microsoft primarily to promote MSN as an online service and Internet service provider. At the time, MSN.com also offered a custom start page and an Internet tutorial, but Microsoft's major web portal was known as "Microsoft Internet Start", and was located at home.microsoft.com.
Internet Start served as the default home page for Internet Explorer and offered basic information such as news, weather, sports, stocks, entertainment reports, links to other websites on the Internet, articles by Microsoft staff members, and software updates for Windows. Microsoft's original news website, https://msnbc.com (n |
https://en.wikipedia.org/wiki/MPEG-7 | MPEG-7 is a multimedia content description standard. It was standardized in ISO/IEC 15938 (Multimedia content description interface). This description will be associated with the content itself, to allow fast and efficient searching for material that is of interest to the user. MPEG-7 is formally called Multimedia Content Description Interface. Thus, it is not a standard which deals with the actual encoding of moving pictures and audio, like MPEG-1, MPEG-2 and MPEG-4. It uses XML to store metadata, and can be attached to timecode in order to tag particular events, or synchronise lyrics to a song, for example.
It was designed to standardize:
a set of Description Schemes ("DS") and Descriptors ("D")
a language to specify these schemes, called the Description Definition Language ("DDL")
a scheme for coding the description
The combination of MPEG-4 and MPEG-7 has been sometimes referred to as MPEG-47.
Introduction
MPEG-7 is intended to complement the previous MPEG standards, by standardizing multimedia metadata -- information about the content, not the content itself. MPEG-7 can be used independently of the other MPEG standards - the description might even be attached to an analog movie. The representation that is defined within MPEG-4, i.e. the representation of audio-visual data in terms of objects, is however very well suited to what will be built on the MPEG-7 standard. This representation is basic to the process of categorization. In addition, MPEG-7 descriptions could be used to improve the functionality of previous MPEG standards. With these tools, we can build an MPEG-7 Description and deploy it. According to the requirements document,1 "a Description consists of a Description Scheme (structure) and the
set of Descriptor Values (instantiations) that
describe the Data." A Descriptor Value is "an instantiation of a Descriptor for a given data set (or subset thereof)."
The Descriptor is the syntactic and semantic definition of the content.
Extraction algori |
https://en.wikipedia.org/wiki/Thermal%20radiation | Thermal radiation is electromagnetic radiation generated by the thermal motion of particles in matter. Thermal radiation is generated when heat from the movement of charges in the material (electrons and protons in common forms of matter) is converted to electromagnetic radiation. All matter with a temperature greater than absolute zero emits thermal radiation. At room temperature, most of the emission is in the infrared (IR) spectrum. Particle motion results in charge-acceleration or dipole oscillation which produces electromagnetic radiation.
Infrared radiation emitted by animals (detectable with an infrared camera) and cosmic microwave background radiation are examples of thermal radiation.
If a radiation object meets the physical characteristics of a black body in thermodynamic equilibrium, the radiation is called blackbody radiation. Planck's law describes the spectrum of blackbody radiation, which depends solely on the object's temperature. Wien's displacement law determines the most likely frequency of the emitted radiation, and the Stefan–Boltzmann law gives the radiant intensity.
Thermal radiation is also one of the fundamental mechanisms of heat transfer.
Overview
Thermal radiation is the emission of electromagnetic waves from all matter that has a temperature greater than absolute zero. Thermal radiation reflects the conversion of thermal energy into electromagnetic energy. Thermal energy is the kinetic energy of random movements of atoms and molecules in matter. All matter with a nonzero temperature is composed of particles with kinetic energy. These atoms and molecules are composed of charged particles, i.e., protons and electrons. The kinetic interactions among matter particles result in charge acceleration and dipole oscillation. This results in the electrodynamic generation of coupled electric and magnetic fields, resulting in the emission of photons, radiating energy away from the body. Electromagnetic radiation, including visible light, will pr |
https://en.wikipedia.org/wiki/Germ%20theory%20of%20disease | The germ theory of disease is the currently accepted scientific theory for many diseases. It states that microorganisms known as pathogens or "germs" can cause disease. These small organisms, too small to be seen without magnification, invade humans, other animals, and other living hosts. Their growth and reproduction within their hosts can cause disease. "Germ" refers to not just a bacterium but to any type of microorganism, such as protists or fungi, or even non-living pathogens that can cause disease, such as viruses, prions, or viroids. Diseases caused by pathogens are called infectious diseases. Even when a pathogen is the principal cause of a disease, environmental and hereditary factors often influence the severity of the disease, and whether a potential host individual becomes infected when exposed to the pathogen.
Pathogens are disease-carrying agents that can pass from one individual to another, both in humans and animals. Infectious diseases are caused by biological agents such as pathogenic microorganisms (viruses, bacteria, and fungi) as well as parasites.
Basic forms of germ theory were proposed by Girolamo Fracastoro in 1546, and expanded upon by Marcus von Plenciz in 1762. However, such views were held in disdain in Europe, where Galen's miasma theory remained dominant among scientists and doctors.
By the early 19th century, smallpox vaccination was commonplace in Europe, though doctors were unaware of how it worked or how to extend the principle to other diseases. A transitional period began in the late 1850s with the work of Louis Pasteur. This work was later extended by Robert Koch in the 1880s. By the end of that decade, the miasma theory was struggling to compete with the germ theory of disease. Viruses were initially discovered in the 1890s. Eventually, a "golden era" of bacteriology ensued, during which the germ theory quickly led to the identification of the actual organisms that cause many diseases.
Miasma theory
The miasma theory was t |
https://en.wikipedia.org/wiki/Drooling | Drooling, or slobbering, is the flow of saliva outside the mouth. Drooling can be caused by excess production of saliva, inability to retain saliva within the mouth (incontinence of saliva), or problems with swallowing (dysphagia or odynophagia).
There are some frequent and harmless cases of drooling – for instance, a numbed mouth from either Orajel, or when going to the dentist's office.
Isolated drooling in healthy infants and toddlers is normal and may be associated with teething. It is unlikely to be a sign of disease or complications. Drooling in infants and young children may be exacerbated by upper respiratory infections and nasal allergies.
Some people with drooling problems are at increased risk of inhaling saliva, food, or fluids into the lungs, especially if drooling is secondary to a neurological problem. However, if the body's normal reflex mechanisms (such as gagging and coughing) are not impaired, this is not life-threatening.
Causes
Drooling or sialorrhea can occur during sleep. It is often the result of open-mouth posture from CNS depressants intake or sleeping on one's side. Sometimes while sleeping, saliva does not build up at the back of the throat and does not trigger the normal swallow reflex, leading to the condition. Freud conjectured that drooling occurs during deep sleep, and within the first few hours of falling asleep, since those who are affected by the symptom experience the most severe harm while napping, rather than during overnight sleep.
A sudden onset of drooling may indicate poisoning – especially by pesticides or mercury – or reaction to snake or insect venom. Excess capsaicin can cause drooling as well, an example being the ingestion of particularly high Scoville Unit chili peppers. Some neurological problems cause drooling. Medication can cause drooling, either due to primary action or side-effects; for example the pain-relief medication Orajel can numb the mucosa.
Causes include:
exercise, especially cardiovascular exe |
https://en.wikipedia.org/wiki/Function%20%28mathematics%29 | In mathematics, a function from a set to a set assigns to each element of exactly one element of . The set is called the domain of the function and the set is called the codomain of the function.
Functions were originally the idealization of how a varying quantity depends on another quantity. For example, the position of a planet is a function of time. Historically, the concept was elaborated with the infinitesimal calculus at the end of the 17th century, and, until the 19th century, the functions that were considered were differentiable (that is, they had a high degree of regularity). The concept of a function was formalized at the end of the 19th century in terms of set theory, and this greatly enlarged the domains of application of the concept.
A function is most often denoted by letters such as , and , and the value of a function at an element of its domain is denoted by ; the numerical value resulting from the function evaluation at a particular input value is denoted by replacing with this value; for example, the value of at is denoted by . When the function is not named and is represented by an expression , the value of the function at, say, may be denoted by . For example, the value at of the function that maps to may be denoted by (which results in
A function is uniquely represented by the set of all pairs , called the graph of the function, a popular means of illustrating the function. When the domain and the codomain are sets of real numbers, each such pair may be thought of as the Cartesian coordinates of a point in the plane.
Functions are widely used in science, engineering, and in most fields of mathematics. It has been said that functions are "the central objects of investigation" in most fields of mathematics.
Definition
A function from a set to a set is an assignment of an element of to each element of . The set is called the domain of the function and the set is called the codomain of the function.
A function, its doma |
https://en.wikipedia.org/wiki/Informal%20mathematics | Informal mathematics, also called naïve mathematics, has historically been the predominant form of mathematics at most times and in most cultures, and is the subject of modern ethno-cultural studies of mathematics. The philosopher Imre Lakatos in his Proofs and Refutations aimed to sharpen the formulation of informal mathematics, by reconstructing its role in nineteenth century mathematical debates and concept formation, opposing the predominant assumptions of mathematical formalism. Informality may not discern between statements given by inductive reasoning (as in approximations which are deemed "correct" merely because they are useful), and statements derived by deductive reasoning.
Terminology
Informal mathematics means any informal mathematical practices, as used in everyday life, or by aboriginal or ancient peoples, without historical or geographical limitation. Modern mathematics, exceptionally from that point of view, emphasizes formal and strict proofs of all statements from given axioms. This can usefully be called therefore formal mathematics. Informal practices are usually understood intuitively and justified with examples—there are no axioms. This is of direct interest in anthropology and psychology: it casts light on the perceptions and agreements of other cultures. It is also of interest in developmental psychology as it reflects a naïve understanding of the relationships between numbers and things. Another term used for informal mathematics is folk mathematics, which is ambiguous; the mathematical folklore article is dedicated to the usage of that term among professional mathematicians.
The field of naïve physics is concerned with similar understandings of physics. People use mathematics and physics in everyday life, without really understanding (or caring) how mathematical and physical ideas were historically derived and justified.
History
There has long been a standard account of the development of geometry in ancient Egypt, followed by Greek |
https://en.wikipedia.org/wiki/Scalability | Scalability is the property of a system to handle a growing amount of work. One definition for software systems specifies that this may be done by adding resources to the system.
In an economic context, a scalable business model implies that a company can increase sales given increased resources. For example, a package delivery system is scalable because more packages can be delivered by adding more delivery vehicles. However, if all packages had to first pass through a single warehouse for sorting, the system would not be as scalable, because one warehouse can handle only a limited number of packages.
In computing, scalability is a characteristic of computers, networks, algorithms, networking protocols, programs and applications. An example is a search engine, which must support increasing numbers of users, and the number of topics it indexes. Webscale is a computer architectural approach that brings the capabilities of large-scale cloud computing companies into enterprise data centers.
In distributed systems, there are several definitions according to the authors, some considering the concepts of scalability a sub-part of elasticity, others as being distinct.
In mathematics, scalability mostly refers to closure under scalar multiplication.
In industrial engineering and manufacturing, scalability refers to the capacity of a process, system, or organization to handle a growing workload, adapt to increasing demands, and maintain operational efficiency. A scalable system can effectively manage increased production volumes, new product lines, or expanding markets without compromising quality or performance. In this context, scalability is a vital consideration for businesses aiming to meet customer expectations, remain competitive, and achieve sustainable growth. Factors influencing scalability include the flexibility of the production process, the adaptability of the workforce, and the integration of advanced technologies. By implementing scalable solutions, c |
https://en.wikipedia.org/wiki/MPEG-21 | The MPEG-21 standard, from the Moving Picture Experts Group, aims at defining an open framework for multimedia applications. MPEG-21 is ratified in the standards ISO/IEC 21000 - Multimedia framework (MPEG-21).
MPEG-21 is based on two essential concepts:
definition of a Digital Item (a fundamental unit of distribution and transaction)
users interacting with Digital Items
Digital Items can be considered the kernel of the Multimedia Framework and the users can be considered as who interacts with them inside the Multimedia Framework. At its most basic level, MPEG-21 provides a framework in which one user interacts with another one, and the object of that interaction is a Digital Item. Due to that, we could say that the main objective of the MPEG-21 is to define the technology needed to support users to exchange, access, consume, trade or manipulate Digital Items in an efficient and transparent way.
MPEG-21 Part 9: File Format defined the storage of an MPEG-21 Digital Item in a file format based on the ISO base media file format, with some or all of Digital Item's ancillary data (such as movies, images or other non-XML data) within the same file. It uses filename extensions .m21 or .mp21 and MIME type application/mp21.
Digital Rights Management
MPEG-21 defines also a "Rights Expression Language" standard as means of managing restrictions for digital content usage. As an XML-based standard, MPEG-21 is designed to communicate machine-readable license information and do so in a "ubiquitous, unambiguous and secure" manner.
Among the aspirations for this standard, that the industry hope will put an end to file sharing, is that it will constitute: "A normative open framework for multimedia delivery and consumption for use by all the players in the delivery and consumption chain. This open framework will provide content creators, producers, distributors and service providers with equal opportunities in the MPEG-21 enabled open market."
See also
Digital Rights Managem |
https://en.wikipedia.org/wiki/Division%20by%20zero | In mathematics, division by zero is division where the divisor (denominator) is zero. Such a division can be formally expressed as , where is the dividend (numerator). In ordinary arithmetic, the expression has no meaning, as there is no number that, when multiplied by , gives (assuming ); thus, division by zero is undefined (a type of singularity). Since any number multiplied by zero is zero, the expression is also undefined; when it is the form of a limit, it is an indeterminate form. Historically, one of the earliest recorded references to the mathematical impossibility of assigning a value to is contained in Anglo-Irish philosopher George Berkeley's criticism of infinitesimal calculus in 1734 in The Analyst ("ghosts of departed quantities").
There are mathematical structures in which is defined for some such as in the Riemann sphere (a model of the extended complex plane) and the projectively extended real line; however, such structures do not satisfy every ordinary rule of arithmetic (the field axioms).
In computing, a program error may result from an attempt to divide by zero. Depending on the programming environment and the type of number (e.g., floating point, integer) being divided by zero, it may generate positive or negative infinity by the IEEE 754 floating-point standard, generate an exception, generate an error message, cause the program to terminate, result in a special not-a-number value, or crash.
Elementary arithmetic
When division is explained at the elementary arithmetic level, it is often considered as splitting a set of objects into equal parts. As an example, consider having ten cookies, and these cookies are to be distributed equally to five people at a table. Each person would receive cookies. Similarly, if there are ten cookies, and only one person at the table, that person would receive cookies.
So, for dividing by zero, what is the number of cookies that each person receives when 10 cookies are evenly distributed among 0 peopl |
https://en.wikipedia.org/wiki/Compression%20artifact | A compression artifact (or artefact) is a noticeable distortion of media (including images, audio, and video) caused by the application of lossy compression. Lossy data compression involves discarding some of the media's data so that it becomes small enough to be stored within the desired disk space or transmitted (streamed) within the available bandwidth (known as the data rate or bit rate). If the compressor cannot store enough data in the compressed version, the result is a loss of quality, or introduction of artifacts. The compression algorithm may not be intelligent enough to discriminate between distortions of little subjective importance and those objectionable to the user.
The most common digital compression artifacts are DCT blocks, caused by the discrete cosine transform (DCT) compression algorithm used in many digital media standards, such as JPEG, MP3, and MPEG video file formats. These compression artifacts appear when heavy compression is applied, and occur often in common digital media, such as DVDs, common computer file formats such as JPEG, MP3 and MPEG files, and some alternatives to the compact disc, such as Sony's MiniDisc format. Uncompressed media (such as on Laserdiscs, Audio CDs, and WAV files) or losslessly compressed media (such as FLAC or PNG) do not suffer from compression artifacts.
The minimization of perceivable artifacts is a key goal in implementing a lossy compression algorithm. However, artifacts are occasionally intentionally produced for artistic purposes, a style known as glitch art or datamoshing.
Technically speaking, a compression artifact is a particular class of data error that is usually the consequence of quantization in lossy data compression. Where transform coding is used, it typically assumes the form of one of the basis functions of the coder's transform space.
Images
When performing block-based discrete cosine transform (DCT) coding for quantization, as in JPEG-compressed images, several types of artifacts can |
https://en.wikipedia.org/wiki/Scream%20Tracker | Scream Tracker is a tracker (an integrated multi-track step sequencer and sampler as a software application). It was created by Psi (Sami Tammilehto), one of the founders of the Finnish demogroup Future Crew. It was written in C and assembly language.
The first version (1.0) had monophonic 4-bit output via the PC speaker, as well as 8-bit output via Covox's Speech Thing (a digital-to-analog converter using the parallel port) or a Sound Blaster 1.x card.
The first popular version of Scream Tracker, version 2.2, was published in 1990. Versions prior to 3.0 created STM (Scream Tracker Module) files, while versions 3.0 and above used the S3M (ScreamTracker 3 Module) format.
As of version 3.0, Scream Tracker supports up to 99 8-bit samples, 32 channels, 100 patterns, and 256 order positions. It can also handle up to 9 FM-synthesis channels on sound cards using the popular OPL2/3/4 chipsets, and, unusually, can play PCM samples and FM instruments at the same time. There are channels referred to as R1..8, L1..8 and A1..9 to be assigned to those 32 ones, which gives an effective amount of only 25 channels. 16-position free panning is available using the S8x command, but only on the Gravis Ultrasound. The usage of the A channels requires the presence of an AdLib-compatible card either by itself or alongside another sound card.
The last version of Scream Tracker was 3.21, released in 1994, placing it in competition with FastTracker 2. It was the precursor of the PC tracking scene and its interface inspired newer trackers like Impulse Tracker. Various other trackers (such as Impulse Tracker or OpenMPT) adopted the use of the Scream Tracker's S3M format.
See also
MilkyTracker
References
Audio trackers
Demoscene software
DOS software
1990 software
Assembly language software |
https://en.wikipedia.org/wiki/KNX | KNX is an open standard (see EN 50090, ISO/IEC 14543) for commercial and residential building automation. KNX devices can manage lighting, blinds and shutters, HVAC, security systems, energy management, audio video, white goods, displays, remote control, etc. KNX evolved from three earlier standards; the European Home Systems Protocol (EHS), BatiBUS, and the European Installation Bus (EIB or Instabus).
It can use twisted pair (in a tree, line or star topology), powerline, RF, or IP links. On this network, the devices form distributed applications and tight interaction is possible. This is implemented via interworking models with standardised datapoint types and objects, modelling logical device channels.
Standard
The KNX standard has been built on the OSI-based EIB communication stack extended with the physical layers, configuration modes and application experience of BatiBUS and EHS.
KNX installations can use several physical communication media:
Twisted pair wiring (TP1 Cable) (inherited from the EIB standard). (The previously inherited BatiBUS communication medium (TP0) is no longer part of the KNX Specifications.)
Power-line networking (inherited from EIB standard). (The previously inherited EHS communication medium (PL132) is no longer part of the KNX Specifications.)
Radio (KNX-RF)
IP (also referred to as EIBnet/IP or KNXnet/IP)
KNX is not based on a specific hardware platform and a network can be controlled by anything from an 8-bit microcontroller to a PC, according to the demands of a particular building. The most common form of installation is over twisted pair medium.
KNX is an approved standard by the following organisations, (inter alia):
International standard (ISO/IEC 14543-3)
European standard (CENELEC EN 50090 and CEN EN 13321–1)
US standard (ANSI/ASHRAE 135)
China Guobiao (GB/T 20965)
It is administered by the KNX Association cvba, a non-profit organisation governed by Belgian law which was formed in 1999. The KNX Association had 5 |
https://en.wikipedia.org/wiki/Subphylum | In zoological nomenclature, a subphylum is a taxonomic rank below the rank of phylum.
The taxonomic rank of "subdivision" in fungi and plant taxonomy is equivalent to "subphylum" in zoological taxonomy. Some plant taxonomists have also used the rank of subphylum, for instance monocotyledons as a subphylum of phylum Angiospermae and vertebrates as a subphylum of phylum Chordata.
Taxonomic rank
Subphylum is:
subordinate to the phylum
superordinate to the infraphylum.
Where convenient, subphyla in turn can be divided into infraphyla; in turn such an infraphylum also would be superordinate to any classes or superclasses in the hierarchy.
Examples
Not all fauna phyla are divided into subphyla. Those that are include:
Arthropoda: divided into subphyla Trilobitomorpha, Chelicerata, Myriapoda, Hexapoda and Crustacea,
Brachiopoda: divided into subphyla Linguliformea, Craniformea and Rhynchonelliformea,
Chordata: divided into Tunicata, Cephalochordata, and its largest subphylum Vertebrata.
Examples of infraphyla include the Mycetozoa, the Gnathostomata and the Agnatha.
References
Bibliography
Biology terminology
rank03 |
https://en.wikipedia.org/wiki/Subspecies | In biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species have subspecies, but for those that do there must be at least two. Subspecies is abbreviated subsp. or ssp. and the singular and plural forms are the same ("the subspecies is" or "the subspecies are").
In zoology, under the International Code of Zoological Nomenclature, the subspecies is the only taxonomic rank below that of species that can receive a name. In botany and mycology, under the International Code of Nomenclature for algae, fungi, and plants, other infraspecific ranks, such as variety, may be named. In bacteriology and virology, under standard bacterial nomenclature and virus nomenclature, there are recommendations but not strict requirements for recognizing other important infraspecific ranks.
A taxonomist decides whether to recognize a subspecies. A common criterion for recognizing two distinct populations as subspecies rather than full species is the ability of them to interbreed even if some male offspring may be sterile. In the wild, subspecies do not interbreed due to geographic isolation or sexual selection. The differences between subspecies are usually less distinct than the differences between species.
Nomenclature
The scientific name of a species is a binomial or binomen, and comprises two Latin words, the first denoting the genus and the second denoting the species. The scientific name of a subspecies is formed slightly differently in the different nomenclature codes. In zoology, under the International Code of Zoological Nomenclature (ICZN), the scientific name of a subspecies is termed a trinomen, and comprises three words, namely the binomen followed by the name of the subspecies. For example, the binomen for the leopard is Panthera pardus. The trinomen Panthera pardus fusca denotes |
https://en.wikipedia.org/wiki/Information%20architecture | Information architecture (IA) is the structural design of shared information environments; the art and science of organizing and labelling websites, intranets, online communities and software to support usability and findability; and an emerging community of practice focused on bringing principles of design, architecture and information science to the digital landscape. Typically, it involves a model or concept of information that is used and applied to activities which require explicit details of complex information systems. These activities include library systems and database development.
Definition
Information architecture has somewhat different meanings in different branches of information systems or information technology:
The structural design of shared information environments.
The art and science of organizing and labeling web sites, intranets, online communities, and software to support findability and usability.
An emerging community of practice focused on bringing principles of design and architecture to the digital landscape.
The combination of organization, labeling, search and navigation systems within websites and intranets.
Extracting required parameters/data of Engineering Designs in the process of creating a knowledge-base linking different systems and standards.
A blueprint and navigational aid to the content of information-rich systems.
A subset of data architecture where usable data (a.k.a. information) is constructed in and designed or arranged in a fashion most useful or empirically holistic to the users of this data.
The practice of organizing the information / content / functionality of a web site so that it presents the best user experience it can, with information and services being easily usable and findable (as applied to web design and development).
The conceptual framework surrounding information, providing context, awareness of location and sustainable structure.
Debate
The difficulty in establishing a common definition |
https://en.wikipedia.org/wiki/Complex%20geometry | In mathematics, complex geometry is the study of geometric structures and constructions arising out of, or described by, the complex numbers. In particular, complex geometry is concerned with the study of spaces such as complex manifolds and complex algebraic varieties, functions of several complex variables, and holomorphic constructions such as holomorphic vector bundles and coherent sheaves. Application of transcendental methods to algebraic geometry falls in this category, together with more geometric aspects of complex analysis.
Complex geometry sits at the intersection of algebraic geometry, differential geometry, and complex analysis, and uses tools from all three areas. Because of the blend of techniques and ideas from various areas, problems in complex geometry are often more tractable or concrete than in general. For example, the classification of complex manifolds and complex algebraic varieties through the minimal model program and the construction of moduli spaces sets the field apart from differential geometry, where the classification of possible smooth manifolds is a significantly harder problem. Additionally, the extra structure of complex geometry allows, especially in the compact setting, for global analytic results to be proven with great success, including Shing-Tung Yau's proof of the Calabi conjecture, the Hitchin–Kobayashi correspondence, the nonabelian Hodge correspondence, and existence results for Kähler–Einstein metrics and constant scalar curvature Kähler metrics. These results often feed back into complex algebraic geometry, and for example recently the classification of Fano manifolds using K-stability has benefited tremendously both from techniques in analysis and in pure birational geometry.
Complex geometry has significant applications to theoretical physics, where it is essential in understanding conformal field theory, string theory, and mirror symmetry. It is often a source of examples in other areas of mathematics, including i |
https://en.wikipedia.org/wiki/Logistics%20engineering | Logistics engineering is a field of engineering dedicated to the scientific organization of the purchase, transport, storage, distribution, and warehousing of materials and finished goods. Logistics engineering is a complex science that considers trade-offs in component/system design, repair capability, training, spares inventory, demand history, storage and distribution points, transportation methods, etc., to ensure the "thing" is where it's needed, when it's needed, and operating the way it's needed all at an acceptable cost.
Overview
Logistics is generally concerned with cost centre service activities, but provides value via improved efficiency and customer satisfaction. It can quickly lose that value if the customer becomes dissatisfied. The end customer can include another process or work center inside of the manufacturing facility, a warehouse where items are stocked or the final customer who will use the product. Another approach which has appeared in recent years is the supply chain management. The supply chain also looks at an efficient chaining of the supply / purchase and distribution sides of an organization. While logistics looks at single echelons with the immediate supply and distribution linked up, supply chain looks at multiple echelons/stages, right from procurement of the raw materials to the final distribution of finished goods up to the customer. It is based on the basic premise that the supply and distribution activities if integrated with the manufacturing / logistic activities, can result in better profitability for the organization. The local minimum of total cost of the manufacturing operation is getting replaced by the global minimum of total cost of the whole chain, resulting in better profitability for the chain members and hence lower costs for the products.
Logistics engineering as a discipline is a very important aspect of systems engineering that also includes reliability engineering. It is the science and process whereby relia |
https://en.wikipedia.org/wiki/Belousov%E2%80%93Zhabotinsky%20reaction | A Belousov–Zhabotinsky reaction, or BZ reaction, is one of a class of reactions that serve as a classical example of non-equilibrium thermodynamics, resulting in the establishment of a nonlinear chemical oscillator. The only common element in these oscillators is the inclusion of bromine and an acid. The reactions are important to theoretical chemistry in that they show that chemical reactions do not have to be dominated by equilibrium thermodynamic behavior. These reactions are far from equilibrium and remain so for a significant length of time and evolve chaotically. In this sense, they provide an interesting chemical model of nonequilibrium biological phenomena; as such, mathematical models and simulations of the BZ reactions themselves are of theoretical interest, showing phenomenon as noise-induced order.
An essential aspect of the BZ reaction is its so called "excitability"; under the influence of stimuli, patterns develop in what would otherwise be a perfectly quiescent medium. Some clock reactions such as Briggs–Rauscher and BZ using the tris(bipyridine)ruthenium(II) chloride as catalyst can be excited into self-organising activity through the influence of light.
History
The discovery of the phenomenon is credited to Boris Belousov. In 1951, while trying to find the non-organic analog to the Krebs cycle, he noted that in a mix of potassium bromate, cerium(IV) sulfate, malonic acid, and citric acid in dilute sulfuric acid, the ratio of concentration of the cerium(IV) and cerium(III) ions oscillated, causing the colour of the solution to oscillate between a yellow solution and a colorless solution. This is due to the cerium(IV) ions being reduced by malonic acid to cerium(III) ions, which are then oxidized back to cerium(IV) ions by bromate(V) ions.
Belousov made two attempts to publish his finding, but was rejected on the grounds that he could not explain his results to the satisfaction of the editors of the journals to which he submitted his results. |
https://en.wikipedia.org/wiki/Ex%20situ%20conservation | Ex situ conservation literally means, "off-site conservation". It is the process of protecting an endangered species, variety or breed, of plant or animal outside its natural habitat; for example, by removing part of the population from a threatened habitat and placing it in a new location, an artificial environment which is similar to the natural habitat of the respective animal and within the care of humans, example are zoological parks and wildlife sanctuaries. The degree to which humans control or modify the natural dynamics of the managed population varies widely, and this may include alteration of living environments, reproductive patterns, access to resources, and protection from predation and mortality. Ex situ management can occur within or outside a species' natural geographic range. Individuals maintained ex situ exist outside an ecological niche. This means that they are not under the same selection pressures as wild populations, and they may undergo artificial selection if maintained ex situ for multiple generations.
Agricultural biodiversity is also conserved in ex situ collections. This is primarily in the form of gene banks where samples are stored in order to conserve the genetic resources of major crop plants and their wild relatives.
Facilities
Botanical gardens, zoos, and aquariums
Botanical gardens, zoos, and aquariums are the most conventional methods of ex situ conservation. Also in ex situ conservation, all of which house whole, protected specimens for breeding and reintroduction into the wild when necessary and possible. These facilities provide not only housing and care for specimens of endangered species, but also have an educational value. They inform the public of the threatened status of endangered species and of those factors which cause the threat, with the hope of creating public interest in stopping and reversing those factors which jeopardize a species' survival in the first place. They are the most publicly visited ex situ con |
https://en.wikipedia.org/wiki/Mojibake | Mojibake (; , "character transformation") is the garbled text that is the result of text being decoded using an unintended character encoding. The result is a systematic replacement of symbols with completely unrelated ones, often from a different writing system.
This display may include the generic replacement character ("�") in places where the binary representation is considered invalid. A replacement can also involve multiple consecutive symbols, as viewed in one encoding, when the same binary code constitutes one symbol in the other encoding. This is either because of differing constant length encoding (as in Asian 16-bit encodings vs European 8-bit encodings), or the use of variable length encodings (notably UTF-8 and UTF-16).
Failed rendering of glyphs due to either missing fonts or missing glyphs in a font is a different issue that is not to be confused with mojibake. Symptoms of this failed rendering include blocks with the code point displayed in hexadecimal or using the generic replacement character. Importantly, these replacements are valid and are the result of correct error handling by the software.
Causes
To correctly reproduce the original text that was encoded, the correspondence between the encoded data and the notion of its encoding must be preserved (i.e. the source and target encoding standards must be the same). As mojibake is the instance of non-compliance between these, it can be achieved by manipulating the data itself, or just relabelling it.
Mojibake is often seen with text data that have been tagged with a wrong encoding; it may not even be tagged at all, but moved between computers with different default encodings. A major source of trouble are communication protocols that rely on settings on each computer rather than sending or storing metadata together with the data.
The differing default settings between computers are in part due to differing deployments of Unicode among operating system families, and partly the legacy encodings' |
https://en.wikipedia.org/wiki/Arithmetical%20hierarchy | In mathematical logic, the arithmetical hierarchy, arithmetic hierarchy or Kleene–Mostowski hierarchy (after mathematicians Stephen Cole Kleene and Andrzej Mostowski) classifies certain sets based on the complexity of formulas that define them. Any set that receives a classification is called arithmetical. The arithmetical hierarchy was invented independently by Kleene (1943) and Mostowski (1946).
The arithmetical hierarchy is important in computability theory, effective descriptive set theory, and the study of formal theories such as Peano arithmetic.
The Tarski–Kuratowski algorithm provides an easy way to get an upper bound on the classifications assigned to a formula and the set it defines.
The hyperarithmetical hierarchy and the analytical hierarchy extend the arithmetical hierarchy to classify additional formulas and sets.
The arithmetical hierarchy of formulas
The arithmetical hierarchy assigns classifications to the formulas in the language of first-order arithmetic. The classifications are denoted and for natural numbers n (including 0). The Greek letters here are lightface symbols, which indicates that the formulas do not contain set parameters.
If a formula is logically equivalent to a formula with only bounded quantifiers, then is assigned the classifications and .
The classifications and are defined inductively for every natural number n using the following rules:
If is logically equivalent to a formula of the form , where is , then is assigned the classification .
If is logically equivalent to a formula of the form , where is , then is assigned the classification .
A formula is equivalent to a formula that begins with some existential quantifiers and alternates times between series of existential and universal quantifiers; while a formula is equivalent to a formula that begins with some universal quantifiers and alternates analogously.
Because every first-order formula has a prenex normal form, every formula is assigned at l |
https://en.wikipedia.org/wiki/CBBS | CBBS ("Computerized Bulletin Board System") was a computer program created by Ward Christensen and Randy Suess to allow them and other computer hobbyists to exchange information between each other.
In January 1978, Chicago was hit by the Great Blizzard of 1978, which dumped record amounts of snow throughout the Midwest. Among those caught in the storm were Christensen and Suess, who were members of CACHE, the Chicago Area Computer Hobbyists' Exchange. They had met at that computer club in the mid-1970s and become friends.
Christensen had created a file transfer protocol for sending binary computer files through modem connections, which was called, simply, MODEM. Later improvements to the program motivated a name change into the now familiar XMODEM. The success of this project encouraged further experiments. CACHE members frequently shared programs and had long been discussing some form of file transfer using modems, and Christensen was naturally at the center of these discussions; however, Suess in particular was skeptical of accomplishing such a project by a volunteer committee. Christensen and Suess became enamored of the extended idea of creating a computerized answering machine and message center, which would allow members to call in with their then-new modems and leave announcements for upcoming meetings.
However, they needed some quiet time to set aside for such a project, and the blizzard gave them that time. Christensen worked on the software and Suess cobbled together an S-100 computer to put the program on. They had a working version within two weeks, but claimed soon afterwards that it had taken four so that it wouldn't seem like a "rushed" project. Time and tradition have settled that date to be February 16, 1978. Christensen and Suess described their innovation in an article entitled "Hobbyist Computerized Bulletin Board" in the November 1978 issue of Byte magazine.
Because the Internet was still small and not available to most computer users, use |
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