| accelerator nerves | Certain of the cardiopulmonary splanchnic nerves establishing the sympathetic innervation of the heart; originating from ganglion cells of the superior, middle, and inferior cervical ganglion of the sympathetic trunk, the unmyelinated efferent fibres of the accelerator nerve's stimulate an increase in the heart rate. (05 Mar 2000) |
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| accelerin | An obsolete term for what was once considered an intermediary product of coagulation but is no longer thought to exist. (05 Mar 2000) |
| accelerograph | An apparatus for studying the combustion of powder in guns, etc. Origin: Accelerate + -graph. Source: Websters Dictionary (01 Mar 1998) |
| accelerometer | An instrument for measuring the rate of change of velocity per unit of time. (05 Mar 2000) |
| accensor | One of the functionaries who light and trim the tapers. Origin: LL, from p. P. Accensus. See Accend Source: Websters Dictionary (01 Mar 1998) |
| accent | 1. A superior force of voice or of articulative effort upon some particular syllable of a word or a phrase, distinguishing it from the others. Many English words have two accents, the primary and the secondary; the primary being uttered with a greater stress of voice than the secondary; as in as'pira'tion, where the chief stress is on the third syllable, and a slighter stress on the first. Some words, as an'tiap'o-plec'tic, in-com'pre-hen'si-bil'i-ty, have two secondary accents. 2. A mark or character used in writing, and serving to regulate the pronunciation; especially., a mark to indicate the nature and place of the spoken accent; a mark to indicate the quality of sound of the vowel marked; as, the French accents. In the ancient Greek the acute accent (') meant a raised tone or pitch, the grave, the level tone or simply the negation of accent, the circumflex (~ or ^) a tone raised and then depressed. In works on elocution, the first is often used to denote the rising inflection of the voice; the second, the falling inflection; and the third (^), the compound or waving inflection. In dictionaries, spelling books, and the like, the acute accent is used to designate the syllable which receives the chief stress of voice. 3. Modulation of the voice in speaking; manner of speaking or pronouncing; peculiar or characteristic modification of the voice; tone; as, a foreign accent; a French or a German accent. "Beguiled you in a plain accent." . "A perfect accent." . "The tender accent of a woman's cry." (Prior) 4. A word; a significant tone; (pl) expressions in general; speech. "Winds! on your wings to Heaven her accents bear, Such words as Heaven alone is fit to hear." (Dryden) 5. Stress laid on certain syllables of a verse. 6. A regularly recurring stress upon the tone to mark the beginning, and, more feebly, the third part of the measure. A special emphasis of a tone, even in the weaker part of the measure. The rythmical accent, which marks phrases and sections of a period. The expressive emphasis and shading of a passage. 7. <mathematics> A mark used to denote feet and inches; as, 6' 10'' is six feet ten inches. Origin: F. Accent, L. Accentus; ad + cantus a singing, canere to sing. See Cant. Source: Websters Dictionary (01 Mar 1998) |
| accentor | 1. One who sings the leading part; the director or leader. 2. <ornithology> A genus of European birds (so named from their sweet notes), including the hedge warbler. In America sometimes applied to the water thrushes. Origin: L. Ad. + cantor singer, canere to sing. Source: Websters Dictionary (01 Mar 1998) |
| accentuation | Act of accentuating; applications of accent. Specifically . Pitch or modulation of the voice in reciting portions of the liturgy. Origin: LL. Accentuatio: cf. F. Accentuation. Source: Websters Dictionary (01 Mar 1998) |
| accentuator | A substance, such as aniline, the presence of which allows a combination between a tissue or histologic element and a stain that might otherwise be impossible. Origin: L. Accentus, accent, fr. Cano, to sing (05 Mar 2000) |
| acceptable daily intake | <pharmacology> This is an estimate of the amount of a substance in food that can be ingested daily over a lifetime by humans without appreciable health risk. The concept of the acceptable daily intake has been developed principally by who and FAO and is relevant to chemicals such as additives to foods, residues of pesticides and veterinary drugs in foods. Acceptable daily intakes are derived from laboratory toxicity data, and from human experiences of such chemicals when this is available, and incorporate a safety factor. The acceptable daily intake is thus an estimate of the amount of a substance in food that can be ingested over a lifetime by humans without significant risk to health (for contaminants in food and drinking water, tolerable intakes - daily or weekly - are used). See: tolerable daily intake. (15 Jan 1998) |
| acceptable risk | <statistics> This relates to the potential for suffering disease or injury that will be tolerated by an individual, group, or society in exchange for the benefits of using a substance or process that will cause such disease or injury. Acceptability of risk depends on scientific data, social, economic, and political factors, and on the perceived benefits arising from a chemical or process that creates the risk in question. (15 Jan 1998) |
| acception | Acceptation; the received meaning. "Here the word "baron" is not to be taken in that restrictive sense to which the modern acception hath confined it." (Fuller) Acception of persons or faces, favoritism; partiality. Origin: L. Acceptio a receiving, accepting: cf. F. Acception. Source: Websters Dictionary (01 Mar 1998) |
| acceptor | A compound that will take up a chemical group (e.g., an amine group, a methyl group, a carbamoyl group) from another compound (the donor); under the action of alanine transaminase, l-glutamic acid is an amine donor while pyruvic acid is an amine acceptor. Origin: L. Ac-cipio, pp. -ceptus, to accept (05 Mar 2000) |
| acceptor control | <biochemistry> The regulation of the respiration rate, governed by ADP's ability to be a phosphate group acceptor. (06 May 1997) |
| acceptor RNA | rNA |