| OAS | old age security; oral allergy syndrome; osmotically active substance |
|---|---|
| OAW | oral airways |
| OC | obstetrical conjugate; occlusocervical; office call; on call; only child; optic chiasma; oral contra... |
| OCA | oculocutaneous albinism; olivopontocerebellar atrophy; oral contraceptive agent |
| OCC | object-centered coordinate [method]; oral cholecystography |
| rodent control | The reduction or regulation of the population of noxious, destructive, or dangerous rodents through chemical, biological, or other means. (12 Dec 1998) |
|---|---|
| weed control | <botany> Mechanical or chemical control of unwanted plants. Measures which have to be undertaken in a plant community to guarantee the growth of the desired vegetation. See: herbicide. (09 Oct 1997) |
| communicable disease control | Programs of surveillance designed to prevent the transmission of disease by any means from person to person or from animal to man. (12 Dec 1998) |
| mosquito control | The reduction or regulation of the population of mosquitoes through chemical, biological, or other means. (12 Dec 1998) |
| control | In research, control subjects or control procedures permit comparison with experimental results. The first controlled clinical research was probably done in 1875 by the British naval surgeon James Lind who, on board the HMS Salisbury, gave sailors with scurvy either oranges or lemons or cider or vinegar or nutmeg (or another treatment) and after just six days discovered that the citrus-consuming sailors had recovered from scury, until then the scourge of extended sea voyages, while the sailors who had been given the other treatments remained uncured. (12 Dec 1998) |
| control animal | In research, an animal submitted to the same conditions as the others used for the experiment, but with the crucial factor (such as the injection of antitoxin, the administration of a drug, etc.) omitted. See: control, control experiment. (05 Mar 2000) |
| control arm | The group of participants in a clinical trial who receive standard treatment or a placebo, against which those receiving the experimental treatment are compared. (09 Oct 1997) |
| control element | Generic term for a region of DNA, such as a promoter or enhancer adjacent to (or within) a gene that allows the regulation of gene expression by the binding of transcription factors. (18 Nov 1997) |
| control experiment | An experiment used to check another, to verify the result, or to demonstrate what would have occurred had the factor under study been omitted. See: control, control animal. (05 Mar 2000) |
| control gene | See: operator gene, regulator gene. (05 Mar 2000) |
| control group | A group of subjects participating in the same experiment as another group of subjects, but which is not exposed to the variable under investigation. See: experimental group. (05 Mar 2000) |
| control limit | A regulatory value applied to the airborne concentration in the workplace of a potentially poisonous substance which is judged to be reasonably practicable for the whole spectrum of work activities and which must not normally be exceeded. (09 Oct 1997) |
| Control of Communicable Diseases in Man | The internationally recognised authoritative manual now in the 15th (1990) edition, published by the American Public Health Association. (05 Mar 2000) |
| control plot | A plot in which no vegetation will be cut and natural succession will occur. A control plot serves as a baseline to compare other treatments (Early, Mid and Late Seral). (05 Dec 1998) |
| control release suture | Eyeless suture with thread attached to needle such that the two separate when tension is applied to the thread. (05 Mar 2000) |