| receiver operating characteristic | A plot of the sensitivity of a diagnostic test as a function of non-specificity (one minus the specificity). The ROC curve indicates the intrinsic properties of a test's diagnostic performance and can be used to compare the relative merits of competing procedures. (05 Mar 2000) |
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| receiver operating characteristic curve | A plot of true positive versus false positive results, usually in a trial of a diagnostic test. A graphical means of assessing the ability of a screening test to discriminate between healthy and diseased persons. Synonym: ROC curve. (05 Mar 2000) |
| characteristic | Synonym: character. 2. Typical or distinctive of a particular disorder. (05 Mar 2000) |
| characteristic curve | Sensitometric curve of radiographic film, a plot of the film density versus the logarithm of the relative exposure. Synonym: H and D curve, Hunter and Driffield curve. (05 Mar 2000) |
| characteristic emission | Monochromatic radiation that is produced when an electron is ejected from an atom and another takes its place by jumping from another shell; the energy of the photon is the difference between that of the two shell positions. Synonym: characteristic emission. (05 Mar 2000) |
| characteristic radiation | Monochromatic radiation that is produced when an electron is ejected from an atom and another takes its place by jumping from another shell; the energy of the photon is the difference between that of the two shell positions. Synonym: characteristic emission. (05 Mar 2000) |
| characteristic X-ray | <microscopy> An X-ray having a unique energy that is emitted by an atom in the sample during its de-energization after ionization of one of its electrons by an incident electron. (05 Aug 1998) |
| bounce frequency | <physics> The average frequency of oscillation of a particle trapped in a magnetic mirror as it bounces back and forth between its turning points in regions of high magnetic field. (See also trapped particle, turning points, banana orbit). (09 Oct 1997) |
| radio frequency current drive | <radiobiology> Plasma waves in the radio-frequency range can be used to push plasma particles in such a way that current forms in the plasma, this is a method of non-inductive current drive which would allow for steady-state fusion reactors to operate. (09 Oct 1997) |
| radio frequency heating | <radiobiology> Process for heating the plasma by transferring energy to ions or electrons using waves generated by an external oscillator at an appropriate frequency. (This is similar to how a microwave oven heats food.) There are various types: See: ECRH, ICRH, and Lower Hybrid. (09 Oct 1997) |
| radio frequency or radiofrequency | <physics> Term used to describe electromagnetic radiation with frequencies less than infrared, but greater than audio frequencies, i.e., greater than about 15,000 Hz. Wavelengths are therefore less than about 20,000 km and greater than about 0.01 mm. (These numbers are not precise.) (09 Oct 1997) |
| gene frequency | The relative occurence (expressed as a percentage) of a gene in a given population. (09 Oct 1997) |
| recombination frequency | The frequency at which crossingover occurs between two chromosomal loci--the probability that twoloci will become unlinked during meiosis. (09 Oct 1997) |
| resonant frequency | The frequency at which individual magnetic nuclei absorb or emit radiofrequency energy in magnetic resonance studies. Synonym: resonance. (05 Mar 2000) |
| respiratory frequency | The number of breaths per minute. (05 Mar 2000) |