| hall effect | <physics> Transverse electric field which develops in a conductor (as a result of the Lorentz Force acting on the charge carriers) when current is driven across a magnetic field. (13 Nov 1997) |
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| halo effect | The effect (usually beneficial) that the manner, attention, and caring of a provider have on a patient during a medical encounter, regardless of what medical procedure or services the encounter involves, the influence upon an observation of the observer's perception of the characteristics of the individual observed (other than the characteristics under study) or the influence of the observer's recollection or knowledge of findings on a previous occasion. (05 Mar 2000) |
| halothane effect | <radiology> High incidence (32%) of reduction of, hepatic arterial blood flow, ** thus, halothane shouldn't be used for hepatic angio's in kids (12 Dec 1998) |
| Hawthorne effect | The effect (usually positive or beneficial) of being under study, upon the persons being studied; their knowledge of the study often influences their behaviour. Origin: city in Illinois; site of the Western Electric plant (05 Mar 2000) |
| cytopathic effect | Degenerative changes in cells (especially in tissue culture) associated with the multiplication of certain viruses; when, in tissue culture, spread of virus is restricted by an overlay of agar (or other suitable substance) the cytopathic effect may lead to formation of plaque. (05 Mar 2000) |
| cytopathogenic effect, viral | Visible morphologic changes in cells infected with viruses. It includes shutdown of cellular RNA and protein synthesis, cell fusion, release of lysosomal enzymes, changes in cell membrane permeability, diffuse changes in intracellular structures, presence of viral inclusion bodies, and chromosomal aberrations. It excludes malignant transformation, which is cell transformation, viral. Viral cytopathogenic effects provide a valuable method for identifying and classifying the infecting viruses. (12 Dec 1998) |
| healthy worker effect | Phenomenon of workers' usually exhibiting overall death rates lower than those of the general population due to the fact that the severely ill and disabled are ordinarily excluded from employment. (12 Dec 1998) |
| second gas effect | When a constant concentration of an anaesthetic like halothane is inspired, the increase in alveolar concentration is accelerated by concomitant administration of nitrous oxide, because alveolar uptake of the latter creates a potential subatmospheric intrapulmonary pressure that leads to increased tracheal inflow. (05 Mar 2000) |
| homotropic effect | An effect where two identical ligands (small molecules) allosterically interact with each other. (09 Oct 1997) |
| Purkinje effect | <ophthalmology> In the light-adapted eye, the region of maximal brightness is in the yellow; in the dark-adapted eye, the region of maximal brightness is in the green. Synonym: Purkinje effect, Purkinje shift. (05 Mar 2000) |
| hydrophobic effect | <chemistry> The tendency for the nonpolar portions of a group of lipid molecules to clump together with one another and exclude water and other polar molecules. The polar portions of the lipid molecules end up facing out. The hydrophobic effect is primarily responsible for the construction of lipid bilayers. (09 Oct 1997) |
| side effect | <pharmacology> A consequence other than the one for which an agent or measure is used, as the adverse effects produced by a drug, especially on a tissue or organ system other than the one sought to be benefited by its administration. For example: hair loss may be a side effect of chemotherapy, fatigue may be a side effect of radiation therapy. (14 Oct 1997) |
| hyperchromic effect | An increase in absorptivity (or extinction) at a particular wavelength of light by a solution or substance due to structural changes in a molecule. (05 Mar 2000) |
| sigma effect | The decrease in apparent viscosity that occurs when a suspension, such as blood, is made to flow through a tube of smaller diameter; observed in tubes less than about 0.3 mm in diameter. Synonym: sigma effect. (05 Mar 2000) |
| hypochromic effect | A phenomenon in which an individual molecule, containing several chromophores, has a certain absorptivity (or optical density) at a given wavelength that is less than the sum of the optical densities of the individual chromophores (at that same wavelength). (05 Mar 2000) |