| chromosomal aberration | Any abnormality of a chromosome's number or structure. (09 Oct 1997) |
|---|---|
| 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) |
| spherical 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) |
| 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) |
| anterior longitudinal ligament | <anatomy> The wide fibrous band interconnecting the anterior surfaces of the vertebral bodies. Synonym: lacertus medius, ligamentum longitudinale anterius. (05 Mar 2000) |
| medial longitudinal arch of foot | Formed by the calcaneus, talus, navicular, three cuneiform bones, and the three medial metatarsals. Synonym: arcus pedis longitudinalis pars medialis. (05 Mar 2000) |
| medial longitudinal bundle | A longitudinal bundle of fibres extending from the upper border of the mesencephalon into the cervical segments of the spinal cord, located close to the midline and ventral to the central gray matter; it is composed largely of fibres from the vestibular nuclei ascending to the motor neurons innervating the external eye muscles (abducens, trochlear, and oculomotor nuclei), and descending to spinal cord segments innervating the musculature of the neck. Synonym: fasciculus longitudinalis medialis, Collier's tract, medial longitudinal bundle, posterior longitudinal bundle. (05 Mar 2000) |