| solar elastosis | Elastosis seen histologically in the sun-exposed skin of the elderly or in those who have chronic actinic damage. (05 Mar 2000) |
|---|---|
| elastosis | 1. Degenerative change in elastic tissue. 2. Degeneration of collagen fibres, with altered staining properties resembling elastic tissue, or formation by fibroblast-activated ultraviolet or mast cell mediators of abnormal fibres. Synonym: elastoid degeneration, elastotic degeneration. (05 Mar 2000) |
| elastosis colloidalis conglomerata | Yellow papules developing in sun-damaged skin of the head and backs of the hands, composed of colloid material in the dermis resembling amyloid but with a different ultrastructure. Synonym: colloid acne, colloid pseudomilium, elastosis colloidalis conglomerata. Origin: L. Milium, millet (05 Mar 2000) |
| elastosis dystrophica | Tiny breaks in the elastin-filled tissue in the back of the eye (retinae). These abnormalities are visible to the doctor during an examination using a viewing instrument called an ophthalmoscope. Angioid streaks are seen in patients with pseudoxanthoma elasticum (abbreviated PXE), a rare disorder of degeneration of the elastic fibres with tiny areas of calcification in the skin, back of the eyes (retinae), and blood vessels. Angioid streaks can be associated with blindness. (12 Dec 1998) |
| elastosis perforans serpiginosa | Circinate groups of asymptomatic keratotic papules; the epidermis is thickened around a central plug of dermal elastic tissue which is extruded through the epidermis. (05 Mar 2000) |
| programming, linear | A technique of operations research for solving certain kinds of problems involving many variables where a best value or set of best values is to be found. It is most likely to be feasible when the quantity to be optimised, sometimes called the objective function, can be stated as a mathematical expression in terms of the various activities within the system, and when this expression is simply proportional to the measure of the activities, i.e., is linear, and when all the restrictions are also linear. It is different from computer programming, although problems using linear programming techniques may be programmed on a computer. (12 Dec 1998) |
| non-linear | Not linear. (05 Dec 1998) |
| superficial linear keratitis | Spontaneous, painful keratitis with epithelial erosion and folds in Bowman's membrane. (05 Mar 2000) |
| linear | Pertaining to or resembling a line. Origin: L. Linearis (18 Nov 1997) |
| linear absorption coefficient | That fraction of ionizing radiation absorbed in a unit thickness of a substance or tissue. See: absorption coefficient. (05 Mar 2000) |
| linear acceleration | The rate of change of velocity without a change in direction; e.g., when the speed of an aircraft increases while flying a straight pathway. (05 Mar 2000) |
| linear accelerator | <apparatus> A sophisticated external beam radiotherapy machine which has the capabilities of focussing irradiation (although not very finely). Acronym: LinAC (16 Dec 1997) |
| linear amputation | Amputation performed by a circular incision through the skin, the muscles being similarly divided higher up, and the bone higher still. Synonym: guillotine amputation, linear amputation. (05 Mar 2000) |
| linear atrophy | Bands of thin wrinkled skin, initially red but becoming purple and white, which occur commonly on the abdomen, buttocks, and thighs at puberty and/or during and following pregnancy, and result from atrophy of the dermis and overextension of the skin; also associated with ascites and Cushing's syndrome. Synonym: atrophoderma striatum, lineae albicantes, lineae atrophicae, linear atrophy, stretch marks, stria, striae atrophicae, striate atrophy of skin, traction atrophy, vergeture. (05 Mar 2000) |
| linear dichroism | <chemistry> Differential absorption of right hand and left hand circularly polarized light resulting from molecular asymmetry involving a chromophore group. Circular dichroism is used to study the conformation of proteins in solution. (18 Nov 1997) |