| B1 | induced field in magnetic resonance imaging; radiofrequency magnetic field in nuclear magnetic reson... |
|---|---|
| EPI/STAR | echo planar imaging with signal targeting and alternating radiofrequency |
| rf | radiofrequency; rapid filling |
| RFI | radiofrequency interference; recurrence-free interval; renal failure index |
| FTA-ABS test | Fluorescent Treponemal Antibody ABSorption test |
| RFR | Radiofrequency Radiation |
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| RF-CA | Radiofrequency catheter ablation |
| ADME | Absorption, distribution, metabolism, and excretion |
| AAS | Atomic Absorption Spectrometry |
| AAS | Atomic Absorption Spectrophotometry |
| radiofrequency | 1. Radiant energy of a certain frequency range; e.g., radio and television employ radiant energy having a frequency between 105-1011 Hz, while diagnostic X-rays have a frequency in the range of 3 × 1018 Hz. 2. In magnetic resonance imaging, the energy applied to switch or create a gradient in the magnetic field. (05 Mar 2000) |
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| 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) |
| radiofrequency plugging | <radiobiology> Use of axial ponderomotive force to plug an open-ended device. First demonstrated on RFC-XX, Institute of Plasma Physics, Nagoya University, Nagoya, Japan, and later demonstrated in the Phaedrus device at the University of Wisconsin. (09 Oct 1997) |
| radiofrequency pulse | In nuclear magnetic resonance, a short electromagnetic signal used to change the direction of the magnetic field. See: sequence pulse. (05 Mar 2000) |
| radiofrequency trapping | <radiobiology> Use of RF waves to pitch angle scatter particles flowing axially into a magnetic mirror cell. The particles are scattered out of the loss cone and are trapped. (See entries for pitch angle scattering, magnetic mirror, loss cone.) (09 Oct 1997) |
| absorption | The process of absorbing, specifically: 1. <physiology> The movement and uptake of substances (liquids and solutes) into cells or across tissues such as skin, intestine and kiidney tubules, by way of diffusion or osmosis. 2. <chemistry> The drawing of a gas or liquid into the pores of a permeable solid. 3. <psychology> The devotion of thought to one object or activity, with inattention to others. 4. <radiology> The taking up of energy by matter with which the radiation interacts. 5. <physics> The loss of (electromagnetic) energy to a medium. For instance, an electromagnetic wave which propagates through a plasma will set the electrons into motion. If the electrons make collisions with other particles, they will absorb net energy from the wave. 6. <immunology> A process in which an antigen or antibody is used to pull an analogous antigen or antibody out of a solution. Compare: adsorption. Origin: L. Absorptio (12 Nov 1997) |
| absorption band | The range of wavelengths or frequencies in the electromagnetic spectrum where radiant energy is absorbed by passage through a gaseous, liquid, or dissolved substance; it is exploited for analytical purposes in colourimetry or spectrophotometry, and is usually described in terms of the wavelength where maximum absorbance occurs (i.e., lambdamax). (05 Mar 2000) |
| absorption cell | A small glass chamber with parallel sides, in which absorption spectra of solutions can be obtained. (05 Mar 2000) |
| absorption chromatography | <investigation> Techniques for separating molecules based on differential absorption and elution. Term for separation methods involving flow of a fluid carrier over a nonmobile absorbing phase. (18 Nov 1997) |
| absorption coefficient | <physics> Measures the degree of wave absorption defined as the fraction of wave energy lost as the wave travels a unit distance. See: absorption. (15 Jan 1998) |
| absorption collapse | Pulmonary collapse due to rapid complete obstruction of a large bronchus. (05 Mar 2000) |
| absorption fever | An elevation of temperature often occurring, without other untoward symptoms, shortly after childbirth, assumed to be due to absorption of uterine discharges through abrasions of the vaginal wall. (05 Mar 2000) |
| absorption lines | The dark line's in the solar spectrum due to absorption by the solar and the earth's atmosphere; the phenomenon occurs because rays passing from an incandescent body through a colder medium are absorbed by elements in that medium. (05 Mar 2000) |
| absorption spectroscopy | <investigation> This is the use of a spectrophotometer to measure the ability of particles (solutes) in a solution to absorb light through a range of specific wavelengths. Every compound absorbs light differently, so absorption spectra can be used to identify compounds, measure concentrations, and determine reaction rates. (15 Jan 1998) |
| absorption spectrum | <chemistry> A graph of the amount of light a substance absorbs, plotted as a fuction of energy, frequency or wavelength. (15 Jan 1998) |
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