| breast mass | <oncology, surgery> A breast lump may be benign or cancerous. Examples of breast lumps include: breast abscess, fat necrosis, fibroadenoma, fibrocystic breast disease and breast cancer. A breast biopsy is the best way to determine the aetiology of a breast lump. Remember, 80 to 85% of all biopsies are benign. (27 Sep 1997) |
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| para-sellar mass | <radiology> Mnemonic: SATCHMO, S sphenoid sinus tumour, A aneurysm / adenoma of pituitary, T teratoid lesion, C craniopharyngioma, H hypothalamic glioma / histiocytoma, M meningioma / metastasis, O optic glioma less common lesions: germinoma, epidermoid, hamartoma, chordoma, arachnoid cyst (12 Dec 1998) |
| mass | <chemistry> The quantity of matter in an object. (09 Jan 1998) |
| mass-action ratio | The ratio of the product of all of the product concentrations divided by the product of all of the reactant concentrations of a particular reaction; when the reaction has been completed (i.e., t = ∞), then this ratio is equal to the equilibrium constant. (05 Mar 2000) |
| mass action theory | That large areas of brain tissue function as a whole in learned or intelligent action. (05 Mar 2000) |
| mass action transmission | <epidemiology> Transmission of infection which occurs at a rate directly proportional to the number or density of both susceptibles and infecteds present. Some authors reserve the name mass action for transmission processes of the form b X Y/N , which we associate with STD-type transmission, and describe transmission rates of the form b X Y , as pseudo-mass action ; the two are equivalent if the population size is unchanging. (05 Dec 1998) |
| mass at base of tongue | <radiology> Lingual thyroid, thyroglossal duct cyst, haemangioma, other neoplasm (12 Dec 1998) |
| 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) |
| 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) |