| variable surface glycoprotein | <protein> One of a battery of antigenicdeterminants expressed by a microorganism to elude immune detection. (09 Oct 1997) |
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| random variable | A variable that may assume a set of values, each with fixed probabilities or probability densities (its distribution), in such a way that the total probability assigned to the distribution is unity; the random variable may be discrete, continuous, or mixed discrete-continuous. (05 Mar 2000) |
| mixed discrete-continuous random variable | <statistics> A random variable that may assume some values with probabilities and others with probability densities. For example, in a 35-year-old man with familial polyposis of the colon, the distribution of time until malignant disease occurs consists of a probability that he already has cancer (which would be assigned the waiting time 0), a probability density of developing it in the future and a probability that he will die of some other cause before he develops cancer. (05 Mar 2000) |
| moderator variable | A variable that interacts by virtue of being antecedent or intermediate in the causal pathway. (05 Mar 2000) |
| common variable immunodeficiency | Heterogeneous group of immunodeficiency syndromes characterised by hypogammaglobulinaemia of most isotypes, variable B-cell defects, and the presence of recurrent bacterial infections. (12 Dec 1998) |
| condenser, variable-focus | <microscopy> Essentially an Abbe condenser in which the upper lens element is fixed and the lower movable. The lower lens may be used to focus the illumination between the elements so that it emerges from the stationary lens as a large diameter parallel bundle. The field of low-power objectives may thus be filled without removing the top element. at the opposite extreme it can be adjusted to have a numerical aperture as high as 1.3. See: illumination, critical. (05 Aug 1998) |
| continuous random variable | Continuous variable that may randomly assume any value in its domain but any particular value has no probability of occurring, only a probability density. (05 Mar 2000) |
| continuous variable | A variable that may take on any value in an interval or intervals (its domain). (05 Mar 2000) |
| dependent variable | In experiments, a variable that is influenced by or dependent upon changes in the independent variable; e.g., the amount of a written passage retained (dependent variable) as a function of the different numbers of minutes (independent variable) allowed to study the passage. (05 Mar 2000) |
| discrete random variable | A random variable that may assume a countable number of values, each with a probability strictly greater than zero. (05 Mar 2000) |
| discrete variable | A variable that may assume only a countable (usually finite) number of values. (05 Mar 2000) |
| immunoglobulin variable region | That region of the immunoglobulin (antibody) molecule that varies in its amino acid sequence and composition, confers the antigenic specificity, and is thought to comprise the binding site for the antigen. It is located at the n-terminus of the fab fragment of the immunoglobulin. It includes hypervariable and framework regions, vh family subgroups, and the complementarity-determining region. (12 Dec 1998) |
| independent variable | A characteristic being measured or observed that is hypothesised to influence another event or manifestation (the dependent variable) within a defined area of relationships under study; that is, the independent variable is not influenced by the event or manifestation, but may cause it or contribute to its variation. See: dependent variable. (05 Mar 2000) |
| intermediate variable | A variable in a causal pathway that causes variation in the dependent variable and is itself caused to vary by the independent variable. (05 Mar 2000) |
| intervening variable | An event, such as an attitude or emotion, inferred to occur within an organism between the stimulation and response in such a way as to influence or determine the response. (05 Mar 2000) |