| exposure | <radiobiology> A quantitative measure of x or gamma radiation at a certain place, based on its ability to produce ionisation in air. The former special unit of exposure was the roentgen (R). 1R = 2.58 x 10-4 C/kg. In the international system (SI unit), the special unit is coulomb per kilogram. (Exposure also is frequently used as a synonym for irradiation). (16 Dec 1997) |
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| exposure dose | The radiation dose, expressed in roentgens, delivered at a point in free air. Synonym: air dose. (05 Mar 2000) |
| exposure keratitis | Inflammation of the cornea resulting from irritation caused by inability to close the eyelids. Synonym: lagophthalmic keratitis. (05 Mar 2000) |
| exposure odds ratio | <epidemiology> See Odds ratio. (05 Dec 1998) |
| barium contrast material | This radiopaque contrast material is either swallowed or given as a enema for the purpose of demonstrating the anatomy of the gastrointestinal tract using X-rays. (27 Sep 1997) |
| base material | Any substance from which a denture base may be made, such as shellac, acrylic resin, vulcanite, polystyrene, metal, etc. (05 Mar 2000) |
| breeder material | <radiobiology> In D-T fusion, refers to lithium or lithium-containing substances which are placed in the blanket to convert the fusion neutrons back into tritium, using nuclear transmutation of lithium isotopes. (09 Oct 1997) |
| by-product material | Radioactive material produced by nuclear fission or by neutron irradiation in a nuclear reactor or similar device. (05 Mar 2000) |
| radiopaque contrast material | A radiopaque substance (for example metal) will be highlighted (appear white) on a plain X-ray. The use of iodine containing radiopaque contrast dyes allow enhancement of the anatomy demonstrable with conventional X-ray. (27 Sep 1997) |
| genetic material | A gene, a part of a gene, a group of genes, or fragments of many genes, on a molecule of DNA, a fragment of DNA, a group of DNA molecules, or fragments of many DNA molecules. Could refer to anything from a small fragment of DNA to the entire genome of an organism. (09 Oct 1997) |
| parent material | <ecology> The unconsolidated and more or less weathered mineral or organic matter from which the soil profile is developed. (09 Oct 1997) |
| material | 1. Consisting of matter; not spiritual; corporeal; physical; as, material substance or bodies. "The material elements of the universe." (Whewell) 2. Hence: Pertaining to, or affecting, the physical nature of man, as distinguished from the mental or moral nature; relating to the bodily wants, interests, and comforts. 3. Of solid or weighty character; not insubstantial; of cinsequence; not be dispensed with; important. "Discourse, which was always material, never trifling." (Evelyn) "I shall, in the account of simple ideas, set down only such as are most material to our present purpose." (Locke) 4. <logic> Pertaining to the matter, as opposed to the form, of a thing. See Matter. Material cause. See Cause. Material evidence, evidence which conduces to the proof or disproof of a relevant hypothesis. Synonym: Corporeal, bodily, important, weighty, momentous, essential. Origin: L. Materialis, fr. Materia stuff, matter: cf. F. Materiel. See Matter, and cf. Materiel. Source: Websters Dictionary (01 Mar 1998) |
| piling unmerchantable material | (PUM) A logging contract requirement to remove and pile unmerchantable woody material of a specified size. (05 Dec 1998) |
| plastic restoration material | In dentistry, any material that may be shaped directly to the tooth cavity, such as amalgam, cement, or resin. (05 Mar 2000) |
| contrast material | A substance that is introduced into or around a structure and, because of the difference in absorption of X-rays by the contrast medium and the surrounding tissues, allows radiographic visualisation of the structure. (18 Nov 1997) |