| radio | 1. <physics> The transmission and reception of electric impulses or signals by means of electric waves without a connecting wire, or the use of these waves for the wireless transmission of electric impulses into which sound is converted. 2. <anatomy, prefix> A combining form indicating connection with, or relation to, a radius or ray; specifically, with the radius of the forearm; as, radio-ulnar, radiomuscular, radiocarpal. Origin: L. Radius, ray (21 Jun 2000) |
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| 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) |
| radio label | A mildly radioactive molecule that is used to tag another molecule (such as a protein) so that it can be identified as it goes through some kind of biochemical process. (09 Oct 1997) |
| radio wave | <physics> Electromagnetic radiation with wavelengths of 300 millimetres or longer (even up to several kilometres). Radiation of this type is used to broadcast radio and television signals, and has frequencies up to thousands of megahertz (or one gigahertz). (09 Oct 1997) |
| radio waves | That portion of the electromagnetic spectrum beyond the microwaves, with wavelengths as high as 30 km. They are used in communications, including television. Short wave or hf (high frequency), uhf (ultrahigh frequency) and vhf (very high frequency) waves are used in citisen's band communication. (12 Dec 1998) |
| radio-flagellata | <zoology> A group of Protozoa having both flagella and pseudopodia. Origin: NL. See Radiate, and Flagellata. Source: Websters Dictionary (01 Mar 1998) |
| radioactive | Giving off radiation. (12 Dec 1998) |
| radioactive atom | <chemistry, physics> An atom with an unstable nucleus, which emits particulate or electromagnetic radiation (radioactive emission) to achieve greater stability. See: radionuclide, half-life, Becquerel. (05 Mar 2000) |
| radioactive constant | <physics, radiobiology> The fraction of the amount of a radionuclide that undergoes transition per unit time. Formally: Lamda=dP/dt Where dP is the probability of a given nucleus undergoing spontaneous nuclear transition in the time interval dt. (16 Dec 1997) |
| radioactive contamination | <radiobiology> Radioactive substance dispersed in material or places where it is undesirable. (16 Dec 1997) |
| radioactive cow | Colloquialism for radionuclide generator. See: cow. (05 Mar 2000) |
| radioactive decay | <physics> The process by which a spontaneous change in nuclear state takes place. This process is accompanied by the emission of energy in various specific combinations of electromagnetic and corpuscular radiation and neutrinos. (16 Dec 1997) |
| radioactive equilibrium | <radiobiology> That condition in which the activities of the members of a radioactive chain decrease exponentially in time with the half-life of the chain precursor. Such radioactive equilibrium is only possible when the half-life of the precursor is longer than that of any other chain member. If the precursor half-life is so long that the change in the precursor population during the period of interest can be ignored, all the activities become sensibly equal and the equilibrium is said to be secular, otherwise it is said to be transient. (16 Dec 1997) |
| serum albumin, radio-iodinated | <chemical> Normal human serum albumin mildly iodinated with radioactive iodine (131-I) which has a half-life of 8 days, and emits beta and gamma rays. It is used as a diagnostic aid in blood volume determination. Pharmacological action: radiopharmaceuticals. (12 Dec 1998) |
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