| alternant | <geology> Composed of alternate layers, as some rocks. Origin: L. Alternans, p. Pr., cf. F. Alternant. See Alternate, v. T. Source: Websters Dictionary (01 Mar 1998) |
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| alternaria | A deuteromycetous fungal genus including several plant pathogens and at least one species which produces a highly phytotoxic antibiotic. (12 Dec 1998) |
| alternate | Cause to occur or appear one after the other. (18 Nov 1997) |
| alternate binaural loudness balance test | ABLB test, a test for recruitment in one ear; the comparison of relative loudness of a series of intensities presented alternately to either ear. (05 Mar 2000) |
| alternate cover test | A test to detect phoria or strabismus; attention is directed to a small fixation object, and one eye is covered for several seconds; then the cover is moved quickly to the other eye; if the eye moves when it is uncovered, a strabismus or phoria is present. (05 Mar 2000) |
| alternate day strabismus | Periodic convergent strabismus often occurring every 48 hours. Synonym: alternate day strabismus. (05 Mar 2000) |
| alternately | 1. In reciprocal succession; succeeding by turns; in alternate order. 2. <mathematics> By alternation; when, in a proportion, the antecedent term is compared with antecedent, and consequent. Source: Websters Dictionary (01 Mar 1998) |
| alternating current | Electrical current which alternates direction periodically. (For instance, household electric current is AC alternating at 60 oscillations/sec (60 Hertz) in the United States, and 50 Hertz in many other countries.) Acronym: AC (09 Oct 1997) |
| alternating light test | Test to detect a relative afferent defect in one eye by watching pupillary movements. With the patient fixing in the distance, the light is held on each eye for about a second, and quickly moved to the other eye. Assuming no defect of the innervation to the iris sphincter in one eye (which would produce an anisocoria in light), the eye with the weaker light response has a relative afferent pupillary defect. This asymmetry of pupillomotor input can be estimated by holding neutral density filters in front of the better eye until the pupillary responses of the two eyes are balanced. Synonym: swinging light test. (05 Mar 2000) |
| alternating mydriasis | Mydriasis alternately affecting each eye. (05 Mar 2000) |
| alternating pulse | Mechanical alternation, a pulse regular in time but with alternate beats stronger and weaker, often detectable only with the sphygmomanometer and usually indicating serious myocardial disease. Synonym: pulsus alternans. (05 Mar 2000) |
| alternating strabismus | A form of strabismus in which either eye fixes. (05 Mar 2000) |
| alternating tremor | A form of hyperkinesia characterised by regular, symmetrical, to-and-fro movements (at about 4 per second) that are produced by patterned, alternating contraction of muscles and their antagonists. (05 Mar 2000) |
| alternation | 1. The reciprocal succession of things in time or place; the act of following and being followed by turns; alternate succession, performance, or occurrence; as, the alternation of day and night, cold and heat, summer and winter, hope and fear. 2. <mathematics> Permutation. 3. The response of the congregation speaking alternately with the minister. Alternation of generation. See Generation. Origin: L. Alternatio: cf. F. Alternation. Source: Websters Dictionary (01 Mar 1998) |
| alternation of generations | The occurrence in one life history of two or more different forms differently produced, usually an alternation of a sexual with an asexual form. (09 Oct 1997) |