| VAT | 1) Ventricular Activation Time 2) Video-Assisted Thoracoscopy |
|---|---|
| VGA | Video Graphic(s) Array |
| IVT | index of vertical transmission; interventional video tomography; intrasound vibration test; intraven... |
| PVI | patient video interview; peripheral vascular insufficiency; perivascular infiltration; positron volu... |
| VD | vapor density; vascular disease; vasodilation, vasodilator; venereal disease; venous dilatation; ven... |
| Whipple, Allen | <person> U.S. Surgeon, 1881-1963. See: Whipple's operation. (05 Mar 2000) |
|---|---|
| Corner-Allen test | A test for progestational activity; adult female rabbits are mated during estrus and spayed 18 hours later; the test substance is injected subcutaneously on 5 successive days; the minimal amount required to produce complete progestational proliferation of the endometrium is taken as a unit, equivalent to 1.25 mg of progesterone. (05 Mar 2000) |
| Corner-Allen unit | A unit of progestational activity, measured in rabbits; the minimum dose which, divided into five equal daily portions, produces on the sixth day the uterine changes characteristic of the eighth day of normal pregnancy; the unit has about the same potency as the international unit. (05 Mar 2000) |
| air contrast barium enema | A double contrast enema in which air is introduced after coating of the colon with a dense barium suspension for radiographic study. Synonym: air contrast barium enema. (05 Mar 2000) |
| air contrast enema | A double contrast enema in which air is introduced after coating of the colon with a dense barium suspension for radiographic study. Synonym: air contrast barium enema. (05 Mar 2000) |
| barium contrast material | This radiopaque contrast material is either swallowed or given as a enema for the purpose of demonstrating the anatomy of the gastrointestinal tract using X-rays. (27 Sep 1997) |
| radiopaque contrast | A radiopaque substance (for example metal) will be highlighted (appear white) on a plain X-ray. The use of iodine containing radiopaque contrast dyes allow enhancement of the anatomy demonstrable with conventional X-ray. (27 Sep 1997) |
| radiopaque contrast dye | A radiopaque substance (for example metal) will be highlighted (appear white) on a plain X-ray. The use of iodine containing radiopaque contrast dyes allow enhancement of the anatomy demonstrable with conventional X-ray. (27 Sep 1997) |
| radiopaque contrast material | A radiopaque substance (for example metal) will be highlighted (appear white) on a plain X-ray. The use of iodine containing radiopaque contrast dyes allow enhancement of the anatomy demonstrable with conventional X-ray. (27 Sep 1997) |
| phase-amplitude contrast | <microscopy> The separation and recombination of direct vs. Diffracted rays in a light microscope adjusted to Kohler illumination. at the lower focal plane of the condenser there is an annular diaphragm with an opaque central stop. Through this diaphragm rays are focused as a hollow cone onto the specimen. In the back focal plane of the objective there is a conjugate annular diaphragm (phase plate). If here the undiffracted rays are retarded (by a transparent film of proper thickness on the annulus of the phase plate), bright contrast results. If, instead, the phase-delay film is on the central spot, dark contrast results. With either a bright or a dark-contrast phase plate, the annulus is usually coated with a partially absorbing (very thin) film of silver (Zernike method) or carbon soot (Wilska method) to reduce the higher amplitude (intensity) of the undiffracted rays. (05 Aug 1998) |
| phase contrast | <microscopy> An optical method devised by F. Zernike for converting the focused image of a phase object (one with differences in refractive index or optical path but not in absorbance), which ordinarily is not visible in focus, into an image with good contrast. (05 Aug 1998) |
| phase-contrast microscope | <instrument> A specially constructed microscope that has a special condenser and objective containing a phase-shifting ring whereby small differences in index of refraction are made visible as intensity or contrast differences in the image; particularly useful for examining structural details in transparent specimens such as living or unstained cells and tissues. (05 Mar 2000) |
| phase contrast microscopy | <investigation> A simple nonquantitative form of interference micoscopy of great utility in visualising live cells. Small differences in optical path length due to differences in refractive index and thickness of structures are visualised as differences in light intensity. (18 Nov 1997) |
| microscopy, phase-contrast | A form of interference microscopy in which variations of the refracting index in the object are converted into variations of intensity in the image. This is achieved by the action of a phase plate. (12 Dec 1998) |
| colour-contrast microscope | <instrument> A type of microscope in which the condenser stop is of one colour and the annulus is a complement of it so that unstained objects are observed in one colour on a field of the other. (05 Mar 2000) |