| signal-to-noise ratio | <microscopy> Also sometimes used as an abbreviation for serial number, can be somewhat confusing in the case of electronic equipment. (05 Aug 1998) |
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| split ratio | The fraction of the cells in a fully grown culture of animal cells that should be used to start a subsequent culture. Minimum may be dictated by medium inadequacies that result in poor growth of some cells at high dilution. (18 Nov 1997) |
| standardised mortality ratio | The ratio of the number of events observed in a population to the number that would be expected if the population had the same distribution as a standard or reference population. (05 Mar 2000) |
| nuclear-cytoplasmic ratio | Ratio of volume of nucleus to volume of cytoplasm, fairly constant for a particular cell type and usually increased in malignant neoplasms. (05 Mar 2000) |
| nucleolar-nuclear ratio | Ratio of volume of nucleolus to volume of nucleus, usually increased in malignant neoplasms. (05 Mar 2000) |
| nutritive ratio | The ratio or proportion of digestible protein to digestible non-nitrogenous nutrients in a ration for livestock. (05 Mar 2000) |
| systolic/diastolic ratio | A calculation from pulsed Doppler ultrasound determinations of blood flow velocities that reflects intrinsic resistance in an arterial blood vessel. (05 Mar 2000) |
| international normalised ratio | System established by the world health organization and the international committee on thrombosis and haemostasis for monitoring and reporting blood coagulation tests. Under this system, results are standardised using the international sensitivity index for the particular test reagent/instrument combination used. (12 Dec 1998) |
| IRI/G ratio | The ratio of immunoreactive insulin to serum or plasma glucose; in hypoglycaemic states a ratio of less than 0.3 is usual with the exception of the hypoglycaemia due to insulinoma, where the ratio is often higher than 0.3. (05 Mar 2000) |
| odds ratio | <epidemiology> A comparison of the presence of a risk factor for disease in a sample of diseased subjects and non diseased controls. The number of people with disease who were exposed to a risk factor ( I.e. ) over those with disease who were not exposed ( Io ) divided by those without disease who were exposed ( Ne ) over those without who were not exposed ( No ). Thus OR=(I.e./Io)/(Ne/No)= I.e. No / Io Ne. This measure should be used for case control studies where we retrospectively look at risks in those with and without disease. Also known as exposure odds ratio. (05 Dec 1998) |
| therapeutic ratio | The ratio of the maximally tolerated dose of a drug to the minimal curative or effective dose; LD50 divided by ED50. (05 Mar 2000) |
| tritium-breeding ratio | <radiobiology> The amount of tritium generated by the breeding blanket of a D-T fusion reactor, divided by the amount of tritium burned in the reactor. A tritium breeding ration greater than unity is necessary for self-sufficient fueling. (09 Oct 1997) |
| turn down ratio | The lowest load at which a boiler will operate efficiently as compared to the boiler's maximum design load. (05 Dec 1998) |
| exposure odds ratio | <epidemiology> See Odds ratio. (05 Dec 1998) |
| extraction ratio | The fraction of a substance removed from the blood flowing through the kidney; it is calculated from the formula (A -V)/A, where A and V, respectively, are the concentrations of the substance in arterial and renal venous plasma. (05 Mar 2000) |