| attenuated tuberculosis | A mild chronic form marked by caseous tubercles of the skin and the occurrence of cold abscesses. (05 Mar 2000) |
|---|---|
| attenuated vaccine | Live pathogens that have lost their virulence but are still capable of inducing a protective immune response to the virulent forms of the pathogen, e.g., Sabin polio vaccine. (05 Mar 2000) |
| attenuated virus | A weakened virus that is no longer virulent. Can be used to make a live virus vaccine. (12 Dec 1998) |
| attenuation | <radiobiology> Process by which a beam of radiation is reduced in intensity when passing through material - combination of absorption and scattering processes, leading to a decrease in flux density of beam when projected through matter. (16 Dec 1997) |
| attenuation coefficient | 1. <radiobiology> Compton: The fractional number of photons removed from a beam of radiation per unit thickness of material through which it is passing as a result of Compton effect interactions. 2. Linear: The fractional number of photons removed from a beam of radiation per unit thickness of material through which it is passing due to all absorption and scattering processes. 3. Pair Production: That fractional decrease in the intensity of a beam of ionising radiation due to pair production in a medium through which it passes. 4. Photoelectric Effect: That fractional decrease in the intensity of a beam of ionising radiation due to photoelectric effect in a medium through which it passes. (16 Dec 1997) |
| attenuation compensation | In ultrasonography, an increase in receiver gain with time to compensate for loss in echo amplitude with depth, usually due to attenuation. Synonym: attenuation compensation, depth compensation, time compensation gain, time-compensated gain, time-varied gain control, time-varied gain. (05 Mar 2000) |
| attenuation factor | <radiobiology> A measure of the opacity of a layer of material for radiation transversing it, the ratio of the incident intensity to the transmitted intensity. It is equal to Io/I, where Io and I are the intensities of the incident and emergent radiation, respectively. In the usual sense of exponential absorption (I = Ioe- m x), the attenuation factor is e- m x, where x is the thickness of the material and m is the absorption coefficient. (16 Dec 1997) |
| attenuator | <molecular biology> An RNA sequence that regulates the expression of certain genes by terminating transcription. (09 Oct 1997) |
| attic | Of or pertaining to Attica, in Greece, or to Athens, its principal city; marked by such qualities as were characteristic of the Athenians; classical; refined. Attic base, a peculiar form of molded base for a column or pilaster, described by Vitruvius, applied under the Roman Empire to the Ionic and Corinthian and "Roman Doric" orders, and imitated by the architects of the Renaissance. Attic faith, inviolable faith. Attic purity, special purity of language. Attic salt, Attic wit, a poignant, delicate wit, peculiar to the Athenians. Attic story. See Attic, Attic style, a style pure and elegant. Origin: L. Atticus, Gr. Source: Websters Dictionary (01 Mar 1998) |
| atticomastoid | Relating to the attic of the tympanic cavity and the mastoid antrum or cells. (05 Mar 2000) |
| atticotomy | Operative opening into the tympanic attic. Origin: attic + G. Tome, incision (05 Mar 2000) |
| attire | 1. Dress; clothes; headdress; anything which dresses or adorns; especially, ornamental clothing. "Earth in her rich attire." (Milton) "I 'll put myself in poor and mean attire." (Shak) "Can a maid forget her ornament, or a bride her attire?" (Jer. Ii. 32) 2. The antlers, or antlers and scalp, of a stag or buck. 3. <botany> The internal parts of a flower, included within the calyx and the corolla. Source: Websters Dictionary (01 Mar 1998) |
| attitude | An enduring, learned predisposition to behave in a consistent way toward a given class of objects, or a persistent mental and/or neural state of readiness to react to a certain class of objects, not as they are but as they are conceived to be. (12 Dec 1998) |
| attitude of health personnel | Attitudes of personnel toward their patients, other professionals, toward the medical care system, etc. (12 Dec 1998) |
| attitude to computers | The attitude and behaviour associated with an individual using the computer. (12 Dec 1998) |