| surface envelope model | <biology> A way of treating the hydrodynamics of a ciliary field by considering the whole surface of the ciliate to have an undulating surface. The undulations arise because of metachronism. (18 Nov 1997) |
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| deterministic model | <epidemiology> A mathematical model in which the parameters and variables are not subject to random fluctuations, so that the system is at any time entirely defined by the initial conditions chosen. Contrast with a stochastic model. (05 Dec 1998) |
| discrete time model | <epidemiology> A model in which the system jumps from one state to the next at fixed intervals or timesteps. These difference models are simple to understand but often difficult to analyse; Contrast continuous time models. The parameters in such a model refer to the amount of change over the finite timestep; they are sometimes referred to as finite rates. In a (rather precise) sense, a differential equation is what you eventually get from a difference equation when you let the timestep get smaller and smaller and smaller. (05 Dec 1998) |
| induced fit model | A model to suggest a mode of action of enzymes in which the substrate binds to the active site of the protein, causing a conformational change in the protein. Synonym: Koshland-Nemethy-Filmer model. (05 Mar 2000) |
| transition probability model | A model to account for the apparently random variation in cell cycle time between individual animal tissue cells in culture that postulates that transition from G1 to s phase is probabilistic. Contrasts with hypotheses that require the accumulation of critical levels of particular proteins. (18 Nov 1997) |
| KNF model | <abbreviation> Koshland-Nemethy-Filmer model. (05 Mar 2000) |
| Koshland-Nemethy-Filmer model | <biochemistry, chemistry> A model to explain the allosteric form of cooperativity; in this model, in the absence of ligands, the protein exists in only one conformation; upon binding, the ligand induces a conformational change that may be transmitted to other subunits. Synonym: Adair-Koshland-Nemethy-Filmer model, induced fit model. (05 Mar 2000) |
| fluid bilayer model | Generally accepted model for membranes in cells. In its original form, the model held that proteins floated in a sea of phospholipids arranged as a bilayer with a central hydrophobic domain. Although it is now recognised that some proteins are restrained by interactions with cytoskeletal elements and that the phospholipid annulus around a protein may contain only specific types of lipid, the model is still considered broadly correct. (18 Nov 1997) |
| fluid mosaic model | A model used to conceptualise cell membranes, in it, the membranesare described as a structually and functionally asymmetric lipidbilayer studded with embedded proteins that aid in cross-membrane transport. (09 Oct 1997) |
| lock-and-key model | A model used to suggest the mode of operation of an enzyme in which the substrate fits into the active site of the protein like a key into a lock. (05 Mar 2000) |
| logistic model | A statistical model; in epidemiology, a model of risk as a function of exposure to a risk factor. (05 Mar 2000) |
| Addison's clinical planes | A series of plane's used as landmarks in thoracoabdominal topography; the trunk is divided vertically by a median plane from the upper border of the manubrium of the sternum to the pubic symphysis, by a lateral plane drawn vertically on either side through a point half way between the anterior superior iliac spine and the median plane at the interspinal plane, and by an interspinal plane passing vertically through the anterior superior iliac spine on either side; transversely the trunk is divided by a transthoracic plane passing across the thorax 3.2 cm above the lower border of the body of the sternum, by a transpyloric plane midway between the jugular notch of the sternum and the pubic symphysis, corresponding to the disc between the first and second lumbar vertebrae, and by an intertubercular plane passing through the iliac tubercles and cutting usually the fifth lumbar vertebra; the plane's formed on these lines, and also on transverse plane's cutting the upper edge of the manubrium and the upper edge of the pubic symphysis, constitute the clinical plane's of Addison. (05 Mar 2000) |
| pathology, clinical | A subspecialty of pathology which deals with the laboratory analysis of specimens of human blood and other fluids. (12 Dec 1998) |
| chemistry, clinical | The specialty of analytical chemistry applied to assays of physiologically important substances found in blood, urine, tissues, and other biological fluids for the purpose of aiding the physician in making a diagnosis or following therapy. (12 Dec 1998) |
| pharmacology, clinical | The branch of pharmacology that deals directly with the effectiveness and safety of drugs in humans. (12 Dec 1998) |