| quarter-wave plate | <microscopy> A compensator giving a retardation of about 130 nm, and a phase shift of 1/4 ~, thus constituting a device used with a polarizer and analyser designed to produce circularly polarized light. (05 Aug 1998) |
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| matching | The process of making a study group and a comparison group in an epidemiological study comparable with respect to extraneous or confounding factors such as age, sex, weight, etc. (05 Mar 2000) |
| cross-matching | 1. A test for incompatibility between donor and recipient blood, carried out prior to transfusion to avoid potentially lethal haemolytic reactions between the donor's red blood cells and antibodies in the recipient's plasma, or the reverse; performed by mixing a sample of red blood cells of the donor with plasma of the recipient (major crossmatch) and the red blood cells of the recipient with the plasma of the donor (minor crossmatch). Incompatibility is indicated by clumping of red blood cells and contraindicates use of the donor's blood. 2. In allotransplantation of solid organs (e.g., kidney), a test for identification of antibody in the serum of potential allograft recipients which reacts directly with the lymphocytes or other cells of a potential allograft donor; presence of these antibodies usually, if not always, contraindicates the performance of the transplantation because virtually all such grafts will be subject to a hyperacute type of rejection. (05 Mar 2000) |
| quarter | 1. One of four equal parts into which anything is divided, or is regarded as divided; a fourth part or portion; as, a quarter of a dollar, of a pound, of a yard, of an hour, etc. Hence, specifically: The fourth of a hundred-weight, being 25 or 28 pounds, according as the hundredweight is reckoned at 100 or 112 pounds. The fourth of a ton in weight, or eight bushels of grain; as, a quarter of wheat; also, the fourth part of a chaldron of coal. <astronomy> One of the divisions of an escutcheon when it is divided into four portions by a horizontal and a perpendicular line meeting in the fess point. When two coats of arms are united upon one escutcheon, as in case of marriage, the first and fourth quarters display one shield, the second and third the other. See Quarter. One of the four parts into which the horizon is regarded as divided; a cardinal point; a direction' principal division; a region; a territory. "Scouts each coast light-armed scour, Each quarter, to descry the distant foe." (Milton) A division of a town, city, or county; a particular district; a locality; as, the Latin quarter in Paris. The fourth part of the distance from one point of the compass to another, being the fourth part of 11 deg 15', that is, about 2 deg 49'; called also quarter point. 2. Proper station; specific place; assigned position; special location. "Swift to their several quarters hasted then The cumbrous elements." (Milton) Hence, specifically: A station at which officers and men are posted in battle; usually in the plural. Place of lodging or temporary residence; shelter; entertainment; usually in the plural. "The banter turned as to what quarters each would find." (W. Irving) A station or encampment occupied by troops; a place of lodging for soldiers or officers; as, winter quarters. Treatment shown by an enemy; mercy; especially, the act of sparing the life a conquered enemy; a refraining from pushing one's advantage to extremes. "He magnified his own clemency, now they were at his mercy, to offer them quarter for their lives." (Clarendon) "Cocks and lambs . . . At the mercy of cats and wolves . . . Must never expect better quarter." (L'Estrange) 3. Friendship; amity; concord. To keep quarter, to keep one's proper place, and so be on good terms with another. "In quarter, and in terms like bride and groom." (Shak) "I knew two that were competitors for the secretary's place, . . . And yet kept good quarter between themselves." (Bacon) False quarter, a cleft in the quarter of a horse's foot. Fifth quarter, the hide and fat; a butcher's term. On the quarter, to accept as prisoner, on submission in battle; to forbear to kill, as a vanquished enemy. To keep quarter. See Quarter. Origin: F. Quartier, L. Quartarius a fourth part, fr. Quartus the fourth. See Quart. Source: Websters Dictionary (01 Mar 1998) |
| quarter-crack | See: sand-crack. (05 Mar 2000) |
| quarter evil | 1. A notorious gambler. 2. A disease among calves and sheep, characterised by a settling of gelatinous matter in the legs, and sometimes in the neck. Source: Websters Dictionary (01 Mar 1998) |
| active length-tension curve | The relationship between active isometric tension and preload (rest length) for a contracting muscle. (05 Mar 2000) |
| amplified fragment length polymorphism | <technique> Invented by KeyGene, a Dutch biotech company based in Wageningen, Holland. The technique is now merchandised under licence agreement by Perkin Elmer. Selected markers are amplified in a PCR, which makes amplified fragment length polymorphism an easy and fast tool for strain identification in agriculture, botany, microbiology and animal breeding. Acronym: AFLP (05 Feb 1998) |
| arch length | The amount of space required for the permanent teeth as measured from the mesial aspect of the first molar on one side to the mesial aspect of the first molar on the opposite side, as measured through the contact points along an imaginary line of the dental arch. (05 Mar 2000) |
| arch length deficiency | The difference between the available circumference of the dental arch and that required to accommodate the succedaneous teeth in proper alignment. (05 Mar 2000) |
| available arch length | <dentistry> The amount of space available for the permanent teeth around the dental arch from the first permanent molar on the left to the first permanent molar on the right. (05 Mar 2000) |
| back focal length | <microscopy> As measured on the principal axis, from the second lens vertex to the back focal point of the lens. It is not the equivalent of the focal length. (05 Aug 1998) |
| bellows length | <microscopy> The distance from the eye point to the image plane in a photomicrographic apparatus. (05 Aug 1998) |
| bond length | This is the distance between the nuclei of two atoms which have formed bonds with each other. (09 Oct 1997) |
| passive length-tension curve | The relationship between passive tension and preload (rest length) for a muscle at rest. (05 Mar 2000) |