beta

(bā'tə, bē'-)
n.

1. The second letter of the Greek alphabet.
2. The second item in a series or system of classification.
3. A mathematical measure of the sensitivity of rates of return on a portfolio or a given stock compared with rates of return on the market as a whole. A beta of 1.0 indicates that an asset closely follows the market; a beta greater than 1.0 indicates greater volatility than the market.
4. Physics.
   1. A beta particle.
   2. A beta ray.
5. Chemistry.
   1. The second position from a designated carbon atom in an organic molecule at which an atom or a radical may be substituted.
   2. An isomeric variation of a chemical compound. Used in combination: beta-estradiol.
6. Computer Science. A beta version.

[Greek bēta, of Phoenician origin.]

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Variant: β

The probability, in a hypothesis test concerning the value of a parameter, of accepting the null hypothesis when the alternative hypothesis is, in fact, true. Also referred to as the probability of a Type II error. The value of β depends upon the true parameter value. The probability of rejecting the null hypothesis when the alternative hypothesis is true is the power of the test. Its value is 1−β.

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1. Mostly working, but still under test; usu. used with “in”: in beta. In the Real World, hardware or software systems often go through two stages of release testing: Alpha (in-house) and Beta (out-house?). Beta releases are generally made to a group of lucky (or unlucky) trusted customers.

2. Anything that is new and experimental. “His girlfriend is in beta” means that he is still testing for compatibility and reserving judgment.

3. Flaky; dubious; suspect (since beta software is notoriously buggy).

Historical note: More formally, to beta-test is to test a pre-release (potentially unreliable) version of a piece of software by making it available to selected (or self-selected) customers and users. This term derives from early 1960s terminology for product cycle checkpoints, first used at IBM but later standard throughout the industry. Alpha Test was the unit, module, or component test phase; Beta Test was initial system test. These themselves came from earlier A- and B-tests for hardware. The A-test was a feasibility and manufacturability evaluation done before any commitment to design and development. The B-test was a demonstration that the engineering model functioned as specified. The C-test (corresponding to today's beta) was the B-test performed on early samples of the production design, and the D test was the C test repeated after the model had been in production a while.

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(b) The ratio of collector current to base current in a bipolar junction transistor (BJT).

symbol: β (lower case) or β (upper case); the second letter of the Greek alphabet. For uses see Greek alphabet.

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The second letter of the Greek alphabet, B or β; used to denote the second position in a chemical classification system. Often used in names of chemical compounds to distinguish one of two or more isomers or to indicate the position of substituent atoms or groups in certain compounds. Also used to distinguish types of radioactive decay; brain rhythms or waves; adrenergic receptors; secretory cells of the various organs of the body that stain with basic dyes, such as the beta cells of the pancreas; and the type of hemolysis induced by bacteria that results in a zone of complete hemolysis when grown on blood agar, except for staphylococci.

• b. adrenergic — see adrenergic.
• b.-adrenergic receptors, — β-adrenergic receptors specific sites on effector cells that respond to epinephrine. There are two types: β₁-receptors, found in the heart and small intestine, and β₂-receptors, found in the bronchi, blood vessels and uterus.
• b. agonists — see adrenergic.
• b. barrels — a form of secondary structure of a polypeptide in which β strands of amino acids are wound into a super secondary structure; usually interconnected by α helical regions of the polypeptide on the outside of the molecule.
• b.-blocker — a drug that blocks the action of epinephrine at beta-adrenergic receptors on cells of effector organs. There are two types of these receptors: β₁-receptors in the myocardium and β₂-receptors in the bronchial and vascular smooth muscles. The principal effects of beta-adrenergic stimulation are increased heart rate and contractility, vasodilation of the arterioles that supply the skeletal muscles, and relaxation of bronchial muscles.
• b. brain waves — those having a frequency of more than 10 hertz (pulsations per second); seen during wakefulness. See also electroencephalography.
• b.-carboline indoleamine alkaloid — poisoning causes a nervous syndrome of hyper- or hypomotility, muscle tremor, flexed paresis of fore- or hindlimbs, hypermetria, walking backwards, convulsions. A plant poison found in Peganum, Tribulus, Kallstroemia spp.
• b. carbon — carbon-3 of a molecule or the carbon atom two on from the function group of a molecule, the carbon(s) of which are not included in the lettering.
• b.-endorphin — hormone secreted by central nervous system, hypothalamus, gastrointestinal tract. See also endorphin.
• b. fibrillosis — see amyloidosis.
• b.-folded domains — compact, locally folded region of tertiary structure containing the β-sheets or β-turns.
• b. hemolysin — is a sphingomyelinase and is produced by staphylococci. It produces partial hemolysis of sheep and cattle erythrocytes. It appears to have little pathogenic effect. See also beta hemolysis.
• b.-hydroxy-beta-methylglutaryl coenzyme A — 1. intermediate in the formation of ketones.
— 2. key starting compound in the synthesis of cholesterol.
• b.-hydroxybutyrate — salt of the major circulating ketone body in animals, formed from the reduction of acetoacetic acid.
• b.-hydroxybutyrate dehydrogenase — mitochondrial enzyme catalyzing the NADH-linked-reduction of acetoacetate to β-hydroxybutyrate.
• b.-ketobutyric acid — acetoacetic acid.
• b. particle — an electron emitted from a nucleus.
• b. radiation — see radiation injury, radiotherapy.
• b. sheet (β-sheet) — a common structural feature of many proteins in which the single polypeptide chain is folded back and forth upon itself with each folded section running in an opposite direction to its nearest neighbors. The folded sections are held together by hydrogen bonds and the arrangement which occurs, particularly in the core of proteins, confers great stability on the molecule.
• b. subunit — second-named chain (or subunit) occurring in the functional organization of macromolecules, usually proteins, containing two or more chains.

For a list of words related to beta, see:

• Software, Languages, and Programming - beta: introductory version of new software program still being tested by outside users

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See words rhyming with "beta."

Dansk (Danish)
n. - beta

idioms:

• beta blocker    betablokker
• beta site    teststed
• beta test    betatest
• beta version    betaversion

Nederlands (Dutch)
bèta, cijfer van tweede niveau, tweede van serie, tweede versie van product

Français (French)
n. - bêta

idioms:

• beta blocker    (Méd, Pharm) bêtabloquant
• beta site    (Comput) site bêta
• beta test    (Comput) bêta test
• beta version    (Comput) version bêta

Deutsch (German)
n. - Beta, Zwei

idioms:

• beta blocker    Beta(rezeptoren)blocker
• beta site    Betaseite
• beta test    Betatest
• beta version    Betaversion

Ελληνική (Greek)
n. - δοκιμαστική έκδοση προγράμματος Η/Υ, βαθμός λίαν καλώς
adj. - δοκιμαστικός, δεύτερος
symb. - γράμμα βήτα (του ελληνικού αλφάβητου)

idioms:

• beta blocker    (ιατρ.) βήτα αναστολέας (καρδιολογικό φάρμακο)
• beta site    διαδικτυακός χώρος για τη δοκιμή προγραμμάτων Η/Υ
• beta test    δοκιμασία επιδόσεων προγράμματος Η/Υ
• beta version    δοκιμαστική έκδοση προγράμματος Η/Υ

Italiano (Italian)
beta, sperimentale

idioms:

• beta blocker    betabloccante

Português (Portuguese)
n. - a segunda letra (f) do alfabeto grego, o segundo item (m) em uma série ou sistema de classificação, partícula beta (f) (Fís.), raio beta (m) (Fís.)

idioms:

• beta blocker    bloqueador (m) beta (Med.)

Русский (Russian)
бета, второй

idioms:

• beta blocker    лекарство против сердечного заболевания

Español (Spanish)
n. - beta

idioms:

• beta blocker    betabloqueante
• beta site    (comp) sitio beta, sitio de pruebas
• beta test    prueba beta
• beta version    versión beta, versión preliminar

Svenska (Swedish)
n. - beta (bokstav), godkänd (betyg)
adj. - godkänd
symb. - (betyg) godkänd

中文（简体）(Chinese (Simplified))
贝它, 希腊字母的第二个

idioms:

• beta blocker    阻断剂, beta受体阻滞药品
• beta site    软件发行上市前的试用地方
• beta test    软件发行上市前的试用, Beta测试
• beta version    软件发行上市前的版本

中文（繁體）(Chinese (Traditional))
n. - 貝它, 希臘字母的第二個

idioms:

• beta blocker    阻斷劑, beta受體阻滯藥品
• beta site    軟體發行上市前的試用地方
• beta test    軟體發行上市前的試用, Beta測試
• beta version    軟體發行上市前的版本

한국어 (Korean)
n. - 그리스어의 알파벳 둘째 자, 제2위의 사물

日本語 (Japanese)
n. - ベータ, 2番目のもの

idioms:

• beta blocker    β遮断剤, β遮断薬

العربيه (Arabic)
‏(الاسم) الحرف الثاني في الأب من الحروف اليونانيه (صفه) ما يخص أشعه بيتا (علامه) ثاني‏

עברית (Hebrew)
n. - ‮ביתא (אות)‬

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