| parallax method | Localization of a foreign body by observing the direction of its motion on a fluoroscopic screen while moving the X-ray tube or the screen. (05 Mar 2000) |
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| binocular parallax | The difference in the angles formed by the lines of sight to two objects situated at different distances from the eyes; a factor in the visual perception of depth. Synonym: stereoscopic parallax. (05 Mar 2000) |
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| parallax | 1. The apparent displacement, or difference of position, of an object, as seen from two different stations, or points of view. 2. <astronomy> The apparent difference in position of a body (as the sun, or a star) as seen from some point on the earth's surface, and as seen from some other conventional point, as the earth's center or the sun. Annual parallax, the greatest value of the heliocentric parallax, or the greatest annual apparent change of place of a body as seen from the earth and sun; as, the annual parallax of a fixed star. Binocular parallax, the apparent difference in position of an object as seen separately by one eye, and then by the other, the head remaining unmoved. Diurnal, or Geocentric, parallax, the parallax of a body with reference to the earth's center. This is the kind of parallax that is generally understood when the term is used without qualification. Heliocentric parallax, the parallax of a body with reference to the sun, or the angle subtended at the body by lines drawn from it to the earth and sun; as, the heliocentric parallax of a planet. Horizontal parallax, the geocentric parallx of a heavenly body when in the horizon, or the angle subtended at the body by the earth's radius. Optical parallax, the apparent displacement in position undergone by an object when viewed by either eye singly. Parallax of the cross wires (of an optical instrument), their apparent displacement when the eye changes its position, caused by their not being exactly in the focus of the object glass. Stellar parallax, the annual parallax of a fixed star. Origin: Gr. Alternation, the mutual inclination of two lines forming an angle, fr. To change a little, go aside, deviate; beside, beyond + to change: cf. F. Parallaxe. Cf. Parallel. Source: Websters Dictionary (01 Mar 1998) |
| parallax test | Measurement of the deviation in strabismus by the alternate cover test combined with neutralization of the deviation using prisms. (05 Mar 2000) |
| vertical parallax | The relative vertical displacement of the image when each eye is closed in turn; seen in vertical diplopia, or heterophoria. (05 Mar 2000) |
| heteronymous parallax | The apparent movement of an object toward the closed eye; noted in exophoria. (05 Mar 2000) |
| homonymous parallax | The apparent movement of an object toward the open eye when one is closed; noted in oesophoria. (05 Mar 2000) |
| stereoscopic parallax | The difference in the angles formed by the lines of sight to two objects situated at different distances from the eyes; a factor in the visual perception of depth. Synonym: stereoscopic parallax. (05 Mar 2000) |
| Abbott's method | A method of treatment of scoliosis by use of a series of plaster jackets applied after partial correction of the curvature by external force. (05 Mar 2000) |
| Abell-Kendall method | A standard method for estimation of total serum cholesterol involving saponification of cholesterol ester by hydroxide, extraction with petroleum ether, and colour development with acetic anhydride-sulfuric acid; the method avoids interference by bilirubin, protein, and haemoglobin. (05 Mar 2000) |
| activated sludge method | A method of sewage disposal in which the sewage is treated with 15% bacterially active, liquid sludge, which is produced by repeated vigorous aeration of fresh sewage to form floccules or sediment; when this flocculation process is complete, the resulting activated sludge contains large numbers of bacteria, together with yeasts, molds, and protozoa, which actively effect the oxidation of organic compounds; this mixture is piped to a sedimentation tank, the effluent from which is completely treated sewage. (05 Mar 2000) |
| Altmann-Gersh method | The method of rapidly freezing a tissue and dehydrating it in a vacuum. (05 Mar 2000) |
| Anel's method | Ligation of an artery immediately above (on the proximal side of) an aneurysm. (05 Mar 2000) |
| Antyllus' method | Ligation of the artery above and below an aneurysm, followed by incision into and emptying of the sac. (05 Mar 2000) |
| aristotelian method | A method of study that stresses the relation between a general category and a particular object. (05 Mar 2000) |
| Ashby method | A differential agglutination method for estimating erythrocyte life span; compatible blood possessing a group factor that the recipient lacks is transferred to the recipient; after the transfusion, sera with potent agglutinins for the recipient's red cells are added to samples of the recipient's blood, and the unagglutinated red cells are counted; using this technique the red cell life span in normal persons is found to be 110 to 120 days. (05 Mar 2000) |