| average | <statistics> A value that represents the sum of values divided by the number of values in the set. It represents or summarises the relevant features of a set of values. Origin: M.E. Averays, loss from damage to ship or cargo, fr. It. Avaris, fr. Ar. 'awariya, damaged goods, + damage (05 Mar 2000) |
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| average flow rate | <physiology> The flow rate determined by dividing the total volume passed in a time period divided by the time period, usually quoted in mls per minute. (05 Mar 2000) |
| average megawatt | <physics> One megawatt of capacity produced continuously over a period of one year. 1 MWa = 1 MW x 8760 hours/year = 8,760 Mwh = 8,760,000 kWh. Acronym: MWa (05 Dec 1998) |
| average pulse magnitude | <physics> The amplitude of pulse averaged throughout its duration; identical with peak amplitude for a square wave or pulse without droop. (05 Mar 2000) |
| law of average localization | Visceral pain is most accurately localised in the least mobile viscera and least accurately in the most mobile. (05 Mar 2000) |
| affinity | 1. An inherent likeness or relationship. 2. A special attraction for a specific element, organ or structure. 3. <chemistry> The force that binds atoms in molecules, the tendency of substances to combine by chemical reaction. 4. The strength of noncovalent chemical binding between two substances as measured by the dissociation constant of the complex. 5. <immunology> A thermodynamic expression of the strength of interaction between a single antigen binding site and a single antigenic determinant (and thus of the stereochemical compatibility between them), most accurately applied to interactions among simple, uniform antigenic determinants such as haptens. Expressed as the association constant (K litres mole 1), which, owing to the heterogeneity of affinities in a population of antibody molecules of a given specificity, actually represents an average value (mean intrinsic association constant). 6. <chemistry> The reciprocal of the dissociation constant. Origin: L. Affinitas = relationship (06 Oct 1997) |
| affinity adsorbent | <immunology> A support matrix coated with an affinity antibodies. (06 May 1997) |
| affinity antibody | The measure of the interaction between molecules such as a receptor and its ligand. This interaction is reversible. (05 Mar 2000) |
| affinity chromatography | <investigation> A technique of analytical chemistry used to separate and purify a biological molecule from a mixture, based on the attraction of the molecule of interest to a particular ligand which has been previously attached to a solid, inert substance. The mixture is passed through a column containing the ligand attached to the stationary substance, so that the molecule of interest stays within the column while the rest of the mixture continues through to the end. Then, a different chemical is flushed through the column to detach the molecule from the ligand and bring it out separately from the rest of the mixture. (09 Feb 1998) |
| affinity column | <investigation> A technique of analytical chemistry used to separate and purify a biological molecule from a mixture, based on the attraction of the molecule of interest to a particular ligand which has been previously attached to a solid, inert substance. The mixture is passed through a column containing the ligand attached to the stationary substance, so that the molecule of interest stays within the column while the rest of the mixture continues through to the end. Then, a different chemical is flushed through the column to detach the molecule from the ligand and bring it out separately from the rest of the mixture. (09 Feb 1998) |
| affinity labeling | <technique> A method for tagging molecules, such as enzymes, so that they can be more easily detected and studied. The method works by substituting a synthetic substance which is similar to the substance that the enzyme normally bonds with. (09 Feb 1998) |
| affinity labels | Analogs of those substrates or compounds which bind naturally at the active sites of proteins, enzymes, antibodies, steroids, or physiological receptors. These analogs form a stable covalent bond at the binding site, thereby acting as inhibitors of the proteins or steroids. (12 Dec 1998) |
| affinity tag | <biochemistry, molecular biology> A short amino acid sequence, usually engineered onto the N- or C-terminus of a protein, to make its purification easier. (14 Nov 1997) |
| antibody affinity | A measure of the binding strength between antibody and a simple hapten or antigen determinant. It depends on the closeness of stereochemical fit between antibody combining sites and antigen determinants, on the size of the area of contact between them, and on the distribution of charged and hydrophobic groups. It includes the concept of "avidity," which refers to the strength of the antigen-antibody bond after formation of reversible complexes. (12 Dec 1998) |
| residual affinity | Secondary forces that enable apparently saturated atoms, ions, or molecules to attract other atoms or groups, causing such phenomena as complex formation, hydration, adsorption, etc. (05 Mar 2000) |