| elementary bodies | Old term for virions, especially the largest virus particles, visible by light microscopy when stained. Synonym: platelet. (05 Mar 2000) |
|---|---|
| elementary granule | A particle of blood dust, or haemoconia. (05 Mar 2000) |
| elementary particle interactions | The interactions of particles responsible for their scattering and transformations (decays and reactions). Because of interactions, an isolated particle may decay into other particles. Two particles passing near each other may transform, perhaps into the same particles but with changed momenta (elastic scattering) or into other particles (inelastic scattering). Interactions fall into three groups: strong, electromagnetic, and weak. (12 Dec 1998) |
| elementary particles | <radiobiology> at a nuclear-energy level: electron & positron - seem to be stable, proton - thought to be stable, life greater than 10^30 sec, neutron - decays in ?6 min unless its in a nucleus, which often extends its life. Other particles important for nuclear energy: Muon, neutrino (m, e, tau), photon, Muonic atoms, Pi-meson antiparticles (09 Oct 1997) |
| elementary step | <chemistry> Reaction mechanisms are broken down into elementary steps. For each step the the reactants are directly involved in forming the transition state. Therefore a rate law can be written from an elementary step but not from an overall reaction. (09 Jan 1998) |
| Zimmermann's elementary particle | <haematology> A discoid cell (3m diameter) found in large numbers in blood, important for blood coagulation and for haemostasis by repairing breaches (small breaks) in the walls of blood vessels. Platelet _ granules contain lysosomal enzymes, dense granules contain ADP (a potent platelet aggregating factor) and serotonin (a vasoactive amine). They also release platelet-derived growth factor which presumably contributes to later repair processes by stimulating fibroblast proliferation. Synonym: thrombocytes. (09 Oct 1997) |
| 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) |