| aperture, angular | <microscopy> The angle between the most divergent rays that can pass through a lens to form the image of an object. The angle subtended between the axis of a lens and the largest accepted angle of the image-forming rays. With microscope objectives the trigonometric sine of this angle is used to define numerical aperture but as measured from the axial object point. (05 Aug 1998) |
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| artery of angular gyrus | The last branch of the terminal part of the middle cerebral artery distributed to parts of the temporal parietal and occipital lobes. Synonym: arteria gyri angularis, angular artery. (05 Mar 2000) |
| supra-angular | <anatomy> See Surangular. Source: Websters Dictionary (01 Mar 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) |
| collision frequency | <chemistry> The rate at which chemical species collide, used in theories of chemical kinetics. Also, the frequency with which gaseous molecules collide. (09 Oct 1997) |
| plasma frequency | <radiobiology> The natural collective oscillation frequency of a charge species (electrons, ions, etc.) in a plasma, in the absence of (or at least parallel to) a magnetic field. Also known as Langmuir or Langmuir-Tonks frequency. See: electrostatic waves, plasma oscillations. (09 Oct 1997) |
| mutational frequency | The proportions of mutations in a population. (05 Mar 2000) |
| critical flicker fusion frequency | The minimal number of flashes of light per second at which an intermittent light stimulus no longer stimulates a continuous visual sensation. (05 Mar 2000) |