| antigen shift | Abrupt change in antigens expressed by a species or variety of organisms. Usually seen in microorganisms where the change may allow escape from immune recognition. Antigenic drift is a more gradual change. See: antigenic variation. (18 Nov 1997) |
|---|---|
| axis shift | Deflection of the electrical axis of the heart to the right or left of the normal. See: left axis deviation, right axis deviation, axis. Synonym: axis shift. (05 Mar 2000) |
| gas shift process | A process in which carbon monoxide and hydrogen react in the presence of a catalyst to form methane and water. (05 Dec 1998) |
| chemical shift | Dependence of the resonance frequency of a nucleus on the chemical binding of the atom or molecule in which it is contained. See: chemical shift artifact. (05 Mar 2000) |
| chemical shift artifact | In magnetic resonance imaging, a dark band caused by a biochemical difference in resonant frequency of adjacent regions rather than a true anatomic separation. (05 Mar 2000) |
| chloride shift | When CO2 enters the blood from the tissues, it passes into the red blood cell and is converted by carbonate dehydratase to bicarbonate (HCO3-); HCO3- ion passes out into the plasma while Cl- migrates into the red blood cell. Reverse changes occur in the lungs when CO2 is eliminated from the blood. Synonym: Hamburger's phenomenon. (05 Mar 2000) |
| phase shift | <microscopy> A change in the phase relationship between two alternating quantities of the same frequency. (05 Aug 1998) |
| phyletic shift | <ecology> A measurable change over time in a population which can be physical, morphologic, genetic, and/or behavioural. (09 Oct 1997) |
| pivot shift test | A manoeuvre to detect a deficiency of the anterior cruciate ligament of the knee; when the knee is extended, a sudden subluxation of the lateral tibial condyle upon the distal femur is positive. (05 Mar 2000) |
| Purkinje shift | <ophthalmology> In the light-adapted eye, the region of maximal brightness is in the yellow; in the dark-adapted eye, the region of maximal brightness is in the green. Synonym: Purkinje effect, Purkinje shift. (05 Mar 2000) |
| shift | 1. The act of shifting. Specifically: The act of putting one thing in the place of another, or of changing the place of a thing; change; substitution. "My going to Oxford was not merely for shift of air." (Sir H. Wotton) A turning from one thing to another; hence, an expedient tried in difficalty; often, an evasion; a trick; a fraud. "Reduced to pitiable shifts." "I 'll find a thousand shifts to get away." (Shak) "Little souls on little shifts rely." (Dryden) 2. Something frequently shifted; especially, a woman's under-garment; a chemise. 3. The change of one set of workmen for another; hence, a spell, or turn, of work; also, a set of workmen who work in turn with other sets; as, a night shift. 4. In building, the extent, or arrangement, of the overlapping of plank, brick, stones, etc, that are placed in courses so as to break joints. 5. <chemical> A breaking off and dislocation of a seam; a fault. 6. A change of the position of the hand on the finger board, in playing the violin. To make shift, to contrive or manage in an exigency. "I shall make shift to go without him." "[They] made a shift to keep their own in Ireland." (Milton) Origin: Cf. Icel skipti. See Shift. Source: Websters Dictionary (01 Mar 1998) |
| shift to the left | A marked increase in the percentage of immature cells in the circulating blood, based on the premise in haematology that the bone marrow with its immature myeloid cells is on the left, while the circulating blood with its mature neutrophils is on the right. Synonym: deviation to the left. See: maturation index. (05 Mar 2000) |
| shift to the right | In a differential count of white blood cells in the peripheral blood, the absence of young and immature forms. Synonym: deviation to the right. See: maturation index. (05 Mar 2000) |
| doppler shift | <radiobiology> The amount of change in the observed frequency of a wave due to the Doppler effect, sometimes called the Doppler frequency. (09 Oct 1997) |
| threshold shift | Measurement of the degree of hearing loss or impairment in terms of a decibel shift from an individual's previous audiogram. (05 Mar 2000) |