| polar plates | Condensed platelike bodies at the ends of the spindle during mitosis of certain types of cells. (05 Mar 2000) |
|---|---|
| polar presentation | The presentation of either pole of the foetal oval; may be either a cephalic or breech presentation, or a longitudinal lie. (05 Mar 2000) |
| polar ring | A thickened, electron-dense ring at the anterior end of certain stages of the Apicomplexa; part of the apical complex characteristic of these sporozoans. (05 Mar 2000) |
| polar solvents | Solvent's that exhibit polar forces on solutes, due to high dipole moment, wide separation of charges, or tight association; e.g., water, alcohols, acids. (05 Mar 2000) |
| polar star | One of the figures forming the diaster. Synonym: polar star. (05 Mar 2000) |
| polar zone | The region in the vicinity of an electrode applied to the body. See: electrotonus. (05 Mar 2000) |
| electro-polar | <physics> Possessing electrical polarity; positively electrified at one end, or on one surface, and negatively at the other; said of a conductor. Source: Websters Dictionary (01 Mar 1998) |
| zinco-polar | <physics> Electrically polarized like the surface of the zinc presented to the acid in a battery, which has zincous affinity. Source: Websters Dictionary (01 Mar 1998) |
| law of polar excitation | A given segment of a nerve is irritated by the development of catelectrotonus and the disappearance of anelectrotonus, but the reverse does not hold; i.e., excitation occurs at the cathode when the circuit is closed and at the anode when it is opened. Synonym: Pfluger's law. (05 Mar 2000) |
| abnormalities, radiation-induced | Congenital changes in the morphology of organs produced by exposure to ionizing or non-ionizing radiation. (12 Dec 1998) |
| accidents, radiation | Accidental dispersal of radioactive materials from a radiation source. Accidents at nuclear reactors can involve large groups of the population from dispersion of radioactivity into the environment and through fallout or a few individuals with high injurious doses. (12 Dec 1998) |
| acoustic radiation | The fibres that pass from the medial geniculate body to the transverse temporal gyri of the cerebral cortex by way of the sublentiform part of the internal capsule. Synonym: radiatio acustica. (05 Mar 2000) |
| acute radiation syndrome | <syndrome> A syndrome caused by exposure of the body to large amounts of radiation, (e.g., from certain forms of therapy, accidents, and nuclear explosions; it is divided into three major forms which are, in ascending order of severity, the haematogic, gastrointestinal, and central nervous system-cardiovascular forms; its clinical manifestations are divided into prodromal, latent, overt, and recovery stages. (05 Mar 2000) |
| adaptive radiation | <chemistry> The evolution of new speciesor sub-species to fill unoccupied ecological niches. (06 May 1997) |
| alpha radiation | <physics, radiobiology> The most easily absorbable type of radiation, it consists of a stream of alpha particles, doubly ionised helium nuclei which are electrically charged and produce intense ionisation in matter. Alpha radiation can be deflected in electromagnetic fields. (09 Oct 1997) |