| mass attenuation coefficient | <physics> The mass attenuation coefficient, u/p, of a material for uncharged ionising particles is the quotient of DN/N by pdl, where DN/N is the fraction of particles that experience interactions in traversing a distance dl in a material of density p. (16 Dec 1997) |
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| mass behaviour | Collective behaviour of an aggregate of individuals giving the appearance of unity of attitude, feeling, and motivation. (12 Dec 1998) |
| mass burn facility | A facility in which the pretreatment of MSW includes only inspection and simple separation to remove oversize, hazardous, or explosive materials. Large mass burn facilities have capacities of 3000 tons of MSW per day or more. Modular plants with capacities as low as 25 tons per day have been built. Mass burn technologies represent over 75% of all the MSW-to-energy facilities constructed in the United States to date. The major components of a mass burn facility include refuse receiving and handling, combustion and steam generation, flue gas cleaning, power generation, condenser cooling water, residue hauling, and storage. (05 Dec 1998) |
| mass chest X-ray | X-ray screening of large groups of persons for diseases of the lung and heart by means of radiography of the chest. (12 Dec 1998) |
| mass defect | <chemistry, radiobiology> Of a nucleus, the difference between the sum of the masses of the constituent nucleons and the mass of the nucleus. (16 Dec 1997) |
| mass effect | <neurology> Damage to the brain due the bulk of a tumour, the blockage of fluid or excess accumulation of fluid within the skull. (16 Dec 1997) |
| mass energy absorption coefficient | <physics> The mass energy absorption coefficient, uen/p of a material for uncharged ionising particles is the product of the mass energy transfer coefficient, utr/p and (1 - g) where g is the fraction of the energy of secondary charged particles that is lost to bremsstrahlung in the material. (16 Dec 1997) |
| mass fragmentography | A microanalytical technique combining mass spectrometry and gas chromatography for the qualitative as well as quantitative determinations of compounds. (12 Dec 1998) |
| mass hysteria | Spontaneous, en masse development of identical physical and/or emotional symptoms among a group of individuals, as seen in a classroom of schoolchildren, a socially contagious frenzy of irrational behaviour in a group of people as a reaction to an event. Synonym: epidemic hysteria. (05 Mar 2000) |
| mass infection | Infection resulting from the entrance of a large number of pathogens into the circulation or tissues. (05 Mar 2000) |
| mass law | <chemistry> This law states that the rate of a given chemical reaction is proportional to concentration of the reactants. (09 Oct 1997) |
| mass media | Instruments or technological means of communication that reach large numbers of people with a common message: press, radio, television, etc. (12 Dec 1998) |
| mass movement | Forcible peristaltic movements of short duration, occurring only three or four times a day, which move the contents of the large intestine from one division to the next, as from the ascending to the transverse colon. Synonym: mass movement. (05 Mar 2000) |
| mass number | The mass of the atom of a particular isotope relative to hydrogen-1 (or to 1/12 the mass of carbon-12), generally very close to the whole number represented by the sum of the protons and neutrons in the atomic nucleus of the isotope (indicated in the name or symbol of the isotope; e.g., oxygen-16, 16O); not to be confused with the atomic weight of an element, which may include a number of isotopes in natural proportion. (05 Mar 2000) |
| mass peristalsis | Forcible peristaltic movements of short duration, occurring only three or four times a day, which move the contents of the large intestine from one division to the next, as from the ascending to the transverse colon. Synonym: mass movement. (05 Mar 2000) |