| quantum | <unit> The fundamental unit of electromagnetic energy. (09 Oct 1997) |
|---|---|
| quantum efficiency | The number of photons required for the formation of one oxygen molecule in photosynthesis. Varies from 8-14 depending on the system used to measure it. (18 Nov 1997) |
| quantum evolution | An extremely rapid evolutionarychange in a single genetic lineage, thought to result from a sudden and radical change in the species'environment. (09 Oct 1997) |
| quantum limit | The shortest wavelength found in an X-ray spectrum. (05 Mar 2000) |
| quantum mottle | Mottle caused by the statistical fluctuation of the number of photons absorbed by the intensifying screens to form the light image on the film; faster screens produce more quantum mottle. (05 Mar 2000) |
| quantum rectum | See: Q.R. Origin: L. However much is correct (05 Mar 2000) |
| quantum requirement | The number of quanta of light absorbed required for the transformation of one molecule; the inverse of the quantum yield. (05 Mar 2000) |
| quantum satis | See: q.s. Origin: L. However much is enough Quantum sink, in radiological imaging, the stage at which statistical information reaches its lowest level because of a low photon flux. (05 Mar 2000) |
| quantum speciation | The rapid evolution of a newspecies from a small population that ispartially or totally isolated from the parent population, the rapidspeciation occurs due to geneticdrift and founder effect and usuallyinvolves a few mutations that have a big impact on the organisms' observable physical traits. (09 Oct 1997) |
| quantum sufficiat | See: q.s. Origin: L. However much is enough (05 Mar 2000) |
| quantum theory | The theory that the radiation and absorption of energy take place in definite quantities called quanta (e) which vary in size and are defined by the equation e=hv in which h is planck's constant and v is the frequency of the radiation. (12 Dec 1998) |
| quantum vis | See: q.v.. Origin: L. However much you wish (05 Mar 2000) |
| quantum yield | The number of photons required for the formation of one oxygen molecule in photosynthesis. Varies from 8-14 depending on the system used to measure it. (18 Nov 1997) |
| acquired platelet function defect | <haematology> Platelet function can be affected by a number of different disease processes including polycythaemia vera, leukaemia, myelofibrosis, renal failure, multiple myeloma and some medications (for example penicillins, salicylates, phenothiazines). Disturbed blood clotting can be manifested by: easy bruising, bleeding gums, nosebleeds, abnormal vaginal bleeding, rectal bleeding, skin rash, vomiting blood, coughing up blood or blood in the urine. A measure of bleeding time and coagulation profile will be part of the evaluation. (29 Dec 1997) |
| aortic septal defect | A small congenital opening between the aorta and pulmonary artery about 1 cm above the semilunar valves, e.g., aorticopulmonary window. Synonym: aorticopulmonary window. (05 Mar 2000) |