| central limit theorem | The sum (or average) of n realizations of the same process, provided only that it has a finite variance, will approach the gaussian distribution as n becomes indefinitely large. This theory provides a broad warrant for the use of normal theory even for nongaussian data. In the form stated here, it constitutes the classical version; more general versions allow serious relaxation of the usual assumptions. (05 Mar 2000) |
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| central line | <equipment> Small, flexible plastic tube inserted into the large vein above the heart, through which drugs and blood products can be given and blood samples withdrawn painlessly. Synonym: central line, Hickman catheter. (12 Jan 1998) |
| central lobule | A division of the superior vermis of the cerebellum between the lingula and the monticulus. Synonym: lobulus centralis cerebelli, central lobule. (05 Mar 2000) |
| central lobule of cerebellum | A division of the superior vermis of the cerebellum between the lingula and the monticulus. Synonym: lobulus centralis cerebelli, central lobule. (05 Mar 2000) |
| central mesenteric lymph nodes | The mesenteric lymph nodes located along the intestinal (jejunal and ileal) branches of the superior mesenteric artery. Synonym: nodi lymphatici superiores centrales, central mesenteric lymph nodes. (05 Mar 2000) |
| central metal ion | <chemistry> The metal ion to which the ligands are attached at the centre of a coordination complex. (09 Oct 1997) |
| central necrosis | Necrosis involving the deeper or inner portions of a tissue, or an organ or its units. (05 Mar 2000) |
| central nervous system | <anatomy, neurology> Pertaining to the brain, cranial nerves and spinal cord. It does not include muscles or peripheral nerves. In invertebrates, the central nervous system is composed of the segmental ganglia of the ventral nerve cord together with the fused ganglia or brain at the anterior end. Acronym: CNS (12 Jan 1998) |
| central nervous system agents | A class of drugs producing both physiological and psychological effects through a variety of mechanisms. They can be divided into "specific" agents, e.g., affecting an identifiable molecular mechanism unique to target cells bearing receptors for that agent, and "non-specific" agents, those producing effects on different target cells and acting by diverse molecular mechanisms. Those with non-specific mechanisms are generally further classed according to whether they produce behavioural depression or stimulation. Those with specific mechanisms are classed by locus of action or specific therapeutic use. (12 Dec 1998) |
| central nervous system depressants | A very loosely defined group of drugs that tend to reduce the activity of the central nervous system. The major groups included here are ethyl alcohol, anaesthetics, hypnotics and sedatives, narcotics, and tranquillising agents (antipsychotics and antianxiety agents). (12 Dec 1998) |
| central nervous system infections | Diseases of the central nervous sytem collectively, caused by pathogenic organisms. (12 Dec 1998) |
| central nervous system neoplasms | Neoplasms located in the brain, spinal cord, or meninges. (12 Dec 1998) |
| central nervous system stimulants | A loosely defined group of drugs that tend to increase behavioural alertness, agitation, or excitation. They work by a variety of mechanisms, but usually not by direct excitation of neurons. The many drugs that have such actions as side effects to their main therapeutic use are not included here. (12 Dec 1998) |
| central neuritis | Inflammation of the nervous substance proper, the axons, and myelin. Synonym: axial neuritis, central neuritis. (05 Mar 2000) |
| central obesity | The deposition of obesity around the trunk sparing the limbs. (27 Sep 1997) |