| NCSI | number of combined spherical irradiation |
|---|---|
| scp | spherical candle power |
| NPV | negative predictive value; pressure value; negative pressure ventilation; net present value; nuclear... |
| PNP | pancreatic polypeptide; para-nitrophenol; peak negative pressure; pediatric nurse practitioner; peri... |
| CNPV | Continuous Negative Pressure Ventilation |
| chromosome aberration | Any deviation from the normal number or morphology of chromosomes; also the phenotypic consequences thereof. (05 Mar 2000) |
|---|---|
| monochromatic aberration | A defect in an optical image arising because of the nature of lenses; the main types are spherical, coma, curvature, and distortion aberration, and astigmatism of oblique pencils. (05 Mar 2000) |
| colour aberration | When using white light through a lens system, it is inevitable that different wave lengths (colours) are brought to a focus at slightly different points. As a consequence, there are chromatic aberations in the image, good microscope objectives are therefore corrected for this at two wave lengths (achromats) or at three wave lengths (apochromats), as well as for spherical aberration. (18 Nov 1997) |
| coma aberration | The distortion of image formation created when a bundle of light rays enters an optical system not parallel to the optic axis. <botany> Any tuft, as the hairs on a seed, or the greenery on a radish or a pineapple. Synonym: coma. Origin: G. Kome, hair, foliage (05 Mar 2000) |
| curvature aberration | Lack of spatial correspondence causing the image of a straight extended object to appear curved. (05 Mar 2000) |
| newtonian aberration | When using white light through a lens system, it is inevitable that different wave lengths (colours) are brought to a focus at slightly different points. As a consequence, there are chromatic aberations in the image, good microscope objectives are therefore corrected for this at two wave lengths (achromats) or at three wave lengths (apochromats), as well as for spherical aberration. (18 Nov 1997) |
| dioptric aberration | <microscopy> A lens defect in which image forming rays passing through the outer zones of the lens focus at a distance from the principal plane, different from that of the rays passing through the centre of the lens. The aberration caused by (near-paraxial) monochromatic light rays or electron beams passing through different radii of a lens not coming to the same focus. (05 Aug 1998) |
| distortion aberration | The faulty formation of an image arising because the magnification of the peripheral part of an object is different from that of the central part when viewed through a lens. (05 Mar 2000) |
| optical aberration | Failure of rays from a point source to form a perfect image after traversing an optical system. (05 Mar 2000) |
| lateral aberration | In spherical aberration, the distance between paraxial focus of central rays on the optic axis. (05 Mar 2000) |
| longitudinal aberration | In spherical aberration, the distance separating the focus of paraxial and peripheral rays on the optic axis. (05 Mar 2000) |
| bone scan: falsely negative metastases | <radiology> Anaplastic tumours, reticulum cell sarcoma, renal cell carcinoma, thyroid carcinoma, histiocytosis, neuroblastoma, multiple myeloma (positive scan usually due to recent or impending fracture) (12 Dec 1998) |
| ventilators, negative-pressure | Body ventilators that assist ventilation by applying intermittent subatmospheric pressure around the thorax, abdomen, or airway and periodically expand the chest wall and inflate the lungs. They are relatively simple to operate and do not require tracheostomy. These devices include the tank ventilators ("iron lung"), portalung, pneumowrap, and chest cuirass ("tortoise shell"). (12 Dec 1998) |
| gram-negative | <microbiology> A common class of bacteria normally found in the gastrointestinal tract that can be responsible for disease in man (sepsis). Bacteria are considered to be gram-negative because of their characteristic staining properties under the microscope, where they either do not stain or are decolourised by alcohol during Gram's method of staining. This is a primary characteristic of bacteria that have a cell wall composed of a thin layer of peptidoglycan covered by an outer membrane of lipoprotein and lipopolysaccharide containing endotoxin. The gram staining characteristics of bacteria have resulted in an important classification system for the identification of bacteria. See: gram-positive (06 Oct 1997) |
| gram-negative aerobic bacteria | <microbiology> A large group of aerobic bacteria which show up as pink (negative) when treated by the gram-staining method. (12 Dec 1998) |