| direct drive | <radiobiology> An approach to inertial-confinement fusion in which the energy of the driver (laser or particle beam) is directly incident on the (usually spherical) target, causing compression heating via ablation of the target surface. (09 Oct 1997) |
|---|---|
| direct embolism | Embolism occurring in the direction of the blood current. (05 Mar 2000) |
| direct filling resin | An autopolymerizing resin especially designed as a dental restorative material. (05 Mar 2000) |
| direct flap | A flap raised completely and transferred at the same stage. Synonym: immediate flap. (05 Mar 2000) |
| direct fluorescent antibody | The straightforward detection of antigens using fluorescent labelled antigen-specific antibody. Because detection of the antigen in a substrate of patient sample (cellular smear, fluid or patient-inoculated culture medium) is the goal, direct fluorescent antibody is seldom quantitative. (05 Mar 2000) |
| direct fluorescent antibody test | Test for tissue antigen using either a direct method, by conjugation of antibody with fluorescent dye (fluorescent antibody technique, direct) or an indirect method, by formation of antigen-antibody complex which is then labelled with fluorescein-conjugated anti-immunoglobulin antibody (fluorescent antibody technique, indirect). The tissue is then examined by fluorescence microscopy. (12 Dec 1998) |
| direct fracture | A fracture, especially of the skull, occurring at the point of injury. (05 Mar 2000) |
| direct illumination | An illumination in which the rays of light are directed downward, almost perpendicularly onto the upper surface of the object, which reflects the rays upward into the optical system. Synonym: erect illumination, vertical illumination. (05 Mar 2000) |
| direct image | <microscopy> Such as seen in a mirror or through a magnifier. A virtual image has no real existence in space as does a real image from a lens. It does have a definite location, however, caused by the angles of divergence of the rays received by the eye. This can be shown by the common school experiment of placing a pin coincident with its mirror image behind a sheet of glass acting as a partial mirror. Its location can also be placed in design by extrapolating backwards to a focus. If a magnifier is used as it should be, with the object at its focus, the virtual image is at infinity. The same is true for a microscope focused for the relaxed eye. See: distance of virtual image. (05 Aug 1998) |
| direct inguinal hernia | See: inguinal hernia. (05 Mar 2000) |
| direct lead | In electrocardiography, a unipolar lead recorded with the exploring electrode placed directly on the surface of the exposed heart. (05 Mar 2000) |
| direct life cycle | <epidemiology> A life cycle in which a parasite is transmitted directly from one host to the next without an intermediate host or vector of another species. (05 Dec 1998) |
| direct lytic factor of cobra venom | A polypeptide of 62 residues; action on cells is similar to that of melittin in that it promotes disruption of membranes; used as an investigational antirheumatic agent. Synonym: cobra toxin, direct lytic factor of cobra venom. (05 Mar 2000) |
| direct lytic factors | most abundant proteins in cobra (naja of the elapids) venom; basic polypeptides of 57 to 62 amino acids with four disulfide bonds and a molecular weight of less than 7000; causes skeletal and cardiac muscle contracture, interferes with neuromuscular and ganglionic transmission, depolarises nerve, muscle and blood cell membranes, thus causing haemolysis. Synonym: cobramine a; cobramine b; cobra cytotoxin; gamma toxin; membrane-active polypeptide. (12 Dec 1998) |
| direct maternal death | Death resulting from obstetric complications of the gestation, labour, or puerperium, and from interventions, omissions, incorrect treatment, or a chain of events caused by any of the above, indirect maternal death, an obstetric death resulting from previously existing disease or from disease developing during pregnancy, labour, or the puerperium; it is not directly due to obstetric causes, but to conditions aggravated by the physiological effects of pregnancy. (05 Mar 2000) |