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English Wikipedia references for Nist.gov 1-50 of 2158
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| International Atomic Time International Atomic Time ( TAI, from the French name Temps Atomique International) is a high-precision atomic coordinate time standard based on the notional passage of proper time on Earth's geoid. It is the principal realisation of Terrestrial Time, and the basis for Coordinated Universal Time (UTC) which is used for civil timekeeping all over the Earth's surface. , TAI was exactly 34 seconds ahead of UTCleap seconds in UTC since 1972 (the last leap second was added on December 31, 2008). International_Atomic_Time | |
| Analysis of variance statistics, analysis of variance (ANOVA) is a collection of statistical models, and their associated procedures, in which the observed variance is partitioned into components due to different explanatory variables. In its simplest form ANOVA gives a statistical test of whether the means of several groups are all equal, and therefore generalizes Student's two-sample t-test to more than two groups. Analysis_of_variance | |
| Albert Einstein Albert (; German:Jewish, German-born, theoretical physicist of the 20th century who is best known for his theories of special relativity and general relativity. He also made important contributions to statistical mechanics, especially his treatment of Brownian motion, his resolution of the paradox of specific heats, and his connection of fluctuations and dissipation. Albert_Einstein | |
| Ampere The ampere (symbolSI unit of electric current. The ampere, in practice often shortened to amp, is an SI base unit, and is named after André-Marie Ampère, one of the main discoverers of electromagnetism. Ampere | |
| Algorithm In mathematics, computing, linguistics, and related subjects, an algorithm is a finite sequence of instructions, an explicit, step-by-step procedure for solving a problem, often used for calculation and data processing. It is formally a type of effective method in which a list of well-defined instructions for completing a task, will when given an initial state, proceed through a well-defined series of successive states, eventually terminating in an end-state. Algorithm | |
| Atom Atom | |
| Artificial intelligence Artificial Intelligence (AI) is the intelligence of machines and the branch of computer science which aims to create it. Major AI textbooks define the field as "the study and design of intelligent agents," John McCarthy, who coined the term in 1956,The field was founded on the claim that a central property of human beings, intelligence—the sapience of Homo sapiens—can be so precisely described that it can be simulated by a machine. Artificial_intelligence | |
| Advanced Encryption Standard In cryptography, the Advanced Encryption Standard (AES) is an encryption standard adopted by the U.S. government. The standard comprises three block ciphers, AES-128, AES-192 and AES-256, adopted from a larger collection originally published as Rijndael. Each AES cipher has a 128-bit block size, with key sizes of 128, 192 and 256 bits, respectively. The AES ciphers have been analyzed extensively and are now used worldwide, as was the case with its predecessor, the Data Encryption Standard (DES). Advanced_Encryption_Standard | |
| Ammonia Ammonia is a compound of nitrogen and hydrogen with the formula NH3. It is normally encountered as a gas with a characteristic pungent odor. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to foodstuffs and fertilizers. Ammonia | |
| Absolute zero Talk:Absolute_zero | |
| Acre The acre is a unit of area in a number of different systems, including the imperial and U.S. customary systems. The most commonly used acres today are the international acre and, in the United States, the survey acre.One international acre is equal to 4,046.8564224m2. One U.S. survey acre is equal to 2 = 4,046.87260982. Acre | |
| American Airlines Flight 77 American Airlines Flight 77 was the third flight hijacked as part of the September 11 attacks, and it was deliberately crashed into the Pentagon. The scheduled U.S. domestic flight from Washington Dulles International Airport, near Washington, D.C., to Los Angeles International Airport was hijacked by five Islamic terrorists less than 35Hani Hanjour, one of the hijackers who was trained as a pilot, assumed control of the flight. American_Airlines_Flight_77 | |
| Array data structure In computer science, an array structure or simply array is a data structure consisting of a collection of elements (values or variables), each identified by one or more integer indices, stored so that the address of each element can be computed from its index tuple by a simple mathematical formula. For example, an array of 10 integer variables, with indices 0 through 9, may be stored as 10 words at memory addresses 2000, 2004, 2008, … 2036; so that the element with index i has address 2000 + 4 × i. Array_data_structure | |
| AVL tree In computer science, an AVL tree is a self-balancing binary search tree, and it is the first such data structure to be invented. In an AVL tree, the heights of the two child subtrees of any node differ by at most one; therefore, it is also said to be height-balanced. AVL_tree | |
| Atomic clock atomic clock is a type of clock that uses an atomic resonance frequency standard as its timekeeping element. They are the most accurate time and frequency standards known, and are used as primary standards for international time distribution services, and to control the frequency of television broadcasts and GPS satellite signals. Atomic_clock | |
| Arthur Stanley Eddington Arthur Stanley Eddington, OM, FRS (28 December 1882 – 22 November 1944) was a British astrophysicist of the early 20th century. The Eddington limit, the natural limit to the luminosity of stars, or the radiation generated by accretion onto a compact object, is named in his honour.He is famous for his work regarding the Theory of Relativity. Arthur_Stanley_Eddington | |
| Abstract data type In computing, an abstract data type (ADT) or abstract data structure is a mathematical model for a certain class of data structures that have similar behavior; or for certain data types of one or more programming languages that have similar semantics. An ADT is defined indirectly, only by the operations that may be performed on it and by mathematical constraints on the effects (and possibly cost) of those operations . Abstract_data_type | |
| Advanced Encryption Standard Talk:Advanced_Encryption_Standard | |
| Air conditioner An air conditioner is a home appliance, system, or mechanism designed to extract heat from an area via a refrigeration cycle. In construction, a complete system of heating, ventilation, and air conditioning is referred to as "HVAC." Its purpose, in a building or an automobile, is to provide comfort during either hot or cold weather. Air_conditioner | |
| Ackermann function computability theory, the Ackermann function or Ackermann–Péter function is a simple example of a computable function that is not primitive recursive. The set of primitive recursive functions is a subset of the set of general recursive functions. Ackermann's function is an example that shows that the former is a strict subset of the latter.The Ackermann function is defined recursively for non-negative integers m and n as follows Ackermann_function | |
| Atomic weight Atomic weight (symbolA) is a dimensionless physical quantity, the ratio of the average mass of atoms of an element (from a given source) to 1/12 of the mass of an atom of carbon-12. The term is usually used, without further qualification, to refer to the standard atomic weights published at regular intervals by the International Union of Pure and Applied Chemistry (IUPAC) and which are intended to be applicable to normal laboratory materials. Atomic_weight | |
| Bit A bit is a binary digit, taking a logical value of either "1" or "0" (also referred to as "true" or "false" respectively). Binary digits are a basic unit of information storage and communication in digital computing and digital information theory. Information theory also often uses the natural digit, called either a nit or a nat. Bit | |
| Bluetooth Bluetooth is an open wireless protocol for exchanging data over short distances from fixed and mobile devices, creating personal area networks (PANs). It was originally conceived as a wireless alternative to RS232 data cables. It can connect several devices, overcoming problems of synchronization. Bluetooth | |
| Boron Boron () is the chemical element with atomic number 5 and the chemical symbol B. Boron is a trivalent metalloid element which occurs abundantly in the evaporite ores borax and ulexite. Several allotropes of boron exist; amorphous boron is a brown powder, though crystalline boron is black, extremely hard (9.3 on Mohs' scale), and a poor conductor at room temperature. Boron | |
| Binomial distribution Also seeNegative binomial distribution. In probability theory and statistics, the binomial distribution is the discrete probability distribution of the number of successes in a sequence of n independent yes/no experiments, each of which yields success with probability p. Binomial_distribution | |
| Binary prefix binary prefix is a set of letters that precede a unit of measure (such as a byte) to indicate multiplication by a power of two. In certain contexts in computing, such as computer memory sizes, units of information storage and communication traffic (Byte) have traditionally been reported in multiples of powers of two. The term binary prefix is intended to differentiate usage of certain symbolic abbreviations (for example, k or kilo) from the SI prefixes, which are always decimal. Binary_prefix | |
| Big O notation Talk:Big_O_notation | |
| Binary search algorithm In computer science, a binary search algorithm (or binary chop) is a technique for locating a particular value in a sorted list. The method makes progressively better guesses, and closes in on the location of the sought value by selecting the middle element in the span (which, because the list is in sorted order, is the median value), comparing its value to the target value, and determining if it is greater than, less than, or equal to the target value. Binary_search_algorithm | |
| Binary search algorithm Talk:Binary_search_algorithm | |
| Binary search tree computer science, a binary search tree (BST) is a binary tree data structure Each node (item in the tree) has a distinct value. Both the left and right subtrees must also be binary search trees. The left subtree of a node contains only values lesser than the node's value. Binary_search_tree | |
| Binary tree computer science, a binary tree is a tree data structure in which each node has at most two children. Typically the child nodes are called left and right. In type theory, a binary tree with nodes of type A is defined inductively as TA = A binary search trees and binary heaps. Binary_tree | |
| Buffer overflow computer security and programming, a buffer overflow, or buffer overrun, is an anomaly where a process stores data in a buffer outside the memory the programmer set aside for it. The extra data overwrites adjacent memory, which may contain other data, including program variables and program flow control data. This may result in erratic program behavior, including memory access errors, incorrect results, program termination (a crash), or a breach of system security. Buffer_overflow | |
| B-tree computer science, a B-tree is a tree data structure that keeps data sorted and allows searches, insertions, and deletions in logarithmic amortized time. Unlike self-balancing binary search trees, it is optimized for systems that read and write large blocks of data. B-tree | |
| Carbon Carbon () is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds. There are three naturally occurring isotopes, with 12C and 13C being stable, while 14C is radioactive, decaying with a half-life of about 5730few elements known since antiquity. Carbon | |
| Candela The candela ( or , symbolcd) is the SI base unit of luminous intensity; that is, power emitted by a light source in a particular direction, weighted by the luminosity function (a standardized model of the sensitivity of the human eye to different wavelengths, also known as the luminous efficiency function Candela | |
| Conversion of units Conversion of units refers to conversion factors between different units of measurement for the same quantity. Conversion_of_units | |
| Key size cryptography, key size or key length is the size (usually measured in bits or bytes) of the key used in a cryptographic algorithm (such as a cipher). An algorithm's key length is distinct from its cryptographic security, which is a logarithmic measure of the fastest known computational attack on the algorithm, also measured in bits. Key_size | |
| Carbon dioxide Carbon dioxide (chemical formula:chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state.Carbon dioxide is used by plants during photosynthesis to make sugars which may either be consumed again in respiration or used as the raw material to produce polysaccharides such as starch and cellulose, proteins and the wide variety of other organic compounds required for plant growth and development. Carbon_dioxide | |
| Computational chemistry Computational chemistry is a branch of chemistry that uses computers to assist in solving chemical problems. It uses the results of theoretical chemistry, incorporated into efficient computer programs, to calculate the structures and properties of molecules and solids. While its results normally complement the information obtained by chemical experiments, it can in some cases predict hitherto unobserved chemical phenomena. It is widely used in the design of new drugs and materials. Computational_chemistry | |
| Charles Sanders Peirce Charles Sanders Peirce ( purse) (September 10, 1839 logician, mathematician, philosopher, and scientist, born in Cambridge, Massachusetts. Peirce was educated as a chemist and employed as a scientist for 30 years. It is largely his contributions to logic, mathematics, philosophy, and semiotics (and his founding of pragmatism) that are appreciated today. In 1934, the philosopher Paul Weiss called Peirce "the most original and versatile of American philosophers and America's greatest logician". Charles_Sanders_Peirce | |
| Clock clock is an instrument used for indicating and maintaining the time and passage thereof. The word clock is derived ultimately (via Dutch, Northern French, and Medieval Latin) from the Celtic words clagan and clocca meaning "bell". For horologists and other specialists the term clock continues to mean exclusively a device with a striking mechanism for announcing intervals of time acoustically, by ringing a bell, a set of chimes, or a gong. Clock | |
| CD-R A CD-R (Compact Disc-Recordable) is a variation of the Compact Disc invented by Philips and Sony. CD-R is a Write Once Read Many (WORM) optical medium, though the whole disk does not have to be entirely written in the same session. CD-R | |
| Concentration = ext{ Molarity of solution}.Such a solution may be described as "0.50 molar." It must be emphasized a 0.5 molar solution contains 0.5 moles of solute in 1.0 liter of solution. This is not equivalent to 1.0 liter of solvent. A 0.5Following the SI system of units, the National Institute of Standards and Technology, the United States authority on measurement, considers the term molarity and the unit symbol M to be obsolete, and suggests instead the amount-of-substance concentration (c) with units mol/m3 or other units used alongside the SI such as mol/L. Concentration | |
| Casimir effect physics, the Casimir effect and the Casimir-Polder force are physical forces arising from a quantized field. The typical example is of two uncharged metallic plates in a vacuum, placed a few micrometers apart, without any external electromagnetic field. In a classical description, the lack of an external field also means that there is no field between the plates, and no force would be measured between them. Casimir_effect | |
| Casimir effect Talk:Casimir_effect | |
| Committee on Data for Science and Technology CODATA (Committee on Data for Science and Technology) was established in 1966 as an interdisciplinary committee of the International Council of Science (ICSU), formerly the International Council of Scientific Unions. It seeks to improve the compilation, critical evaluation, storage, and retrieval of data of importance to science and technology.The CODATA Task Group on Fundamental Constants was established in 1969. Committee_on_Data_for_Science_and_Technology | |
| Diffie-Hellman key exchange Diffie-Hellman key exchange (D-H) is a cryptographic protocol that allows two parties that have no prior knowledge of each other to jointly establish a shared secret key over an insecure communications channel. This key can then be used to encrypt subsequent communications using a symmetric key cipher.Synonyms of Diffie-Hellman key exchange include Diffie-Hellman key agreement Diffie-Hellman key establishment Diffie-Hellman key negotiation Exponential key exchange Diffie-Hellman protocol Diffie-Hellman_key_exchange | |
| Data Encryption Standard The Data Encryption Standard (DES) is a block cipher (a form of shared secret encryption) that was selected by the National Bureau of Standards as an official Federal Information Processing Standard (FIPS) for the United States in 1976 and which has subsequently enjoyed widespread use internationally. Data_Encryption_Standard | |
| Depth of field Talk:Depth_of_field | |
| Day A day (symbol d) is a unit of time equivalent to approximately 24 hours. It is not an SI unit but it is accepted for use with SI. The SI unit of time is the second. Day |
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