| transmitted light | <microscopy> The usual method for illuminating transparent microscopic specimens. The light is concentrated on the specimen by the substage condenser. Objects appear in outline (refraction images) or coloured on a bright field (colour images). (05 Aug 1998) |
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| sexually transmitted disease | <disease> A disease, such as genital herpes, gonorrhoea, HIV or chlamydia, whose usual means of transmission is by sexual contact. (09 Oct 1997) |
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| sexually transmitted diseases | Diseases due to or propagated by sexual contact. (12 Dec 1998) |
| sexually transmitted diseases, bacterial | Bacterial diseases transmitted or propagated by sexual conduct. (12 Dec 1998) |
| sexually transmitted diseases in women | Gonorrhoea and chlamydia are bacterial sexually transmitted diseases (stds) frequently found together. Gonorrhoea is not transmitted from toilet seats. Women infected with it may not have any symptoms but can end up later with severe pelvic infection. Early syphilis causes a mouth or genital ulcer (chancre) and later can cause hair loss, headaches, sore throat, and skin rash. Even later, syphilis can lead to heart and brain damage. Genital herpes is a viral infection that can cause painful genital sores. Genital warts are caused by viruses and can increase a woman's risk for cancer of the cervix. Aids is caused by the human immunodeficiency virus (HIV). Hepatitis b is a virus that causes liver inflammation and can lead to cirrhosis and cancer of the liver. Hepatitis b can now be prevented with a vaccine. There is no safe sex. Condoms do not necessarily prevent stds. (12 Dec 1998) |
| sexually transmitted diseases, viral | Viral diseases which are transmitted or propagated by sexual conduct. (12 Dec 1998) |
| alternating light test | Test to detect a relative afferent defect in one eye by watching pupillary movements. With the patient fixing in the distance, the light is held on each eye for about a second, and quickly moved to the other eye. Assuming no defect of the innervation to the iris sphincter in one eye (which would produce an anisocoria in light), the eye with the weaker light response has a relative afferent pupillary defect. This asymmetry of pupillomotor input can be estimated by holding neutral density filters in front of the better eye until the pupillary responses of the two eyes are balanced. Synonym: swinging light test. (05 Mar 2000) |
| Begg light wire differential force technique | An orthodontic appliance utilizing small gauge labial wires with expansion and contraction loops formed into it and attached to bands fitted to individual teeth; sometimes called Begg light wire differential force technique. (05 Mar 2000) |
| gene rearrangement, b-lymphocyte, light chain | Ordered rearrangement of b-lymphocyte variable gene regions coding for the kappa or lambda light chains, thereby contributing to antibody diversity. It occurs during the second stage of differentiation of the immature b-lymphocyte. (12 Dec 1998) |
| ray, light | <microscopy> The term applied to the lines perpendicular to the wavefronts of waves of light to indicate their direction of travel in an isotropic medium. Note the wave normal and the ray do not coincide in isotropic media. (05 Aug 1998) |
| reflected light | Light directed backward from a mirror. (05 Mar 2000) |
| refracted light | Bent rays of light changed in passage from one transparent medium to another of unequal density. See: refraction. (05 Mar 2000) |
| visible light | <physics> Electromagnetic radiation with wavelengths between 400 nanometres and 750 nanometres. Electromagnetic radiation within this range can be detected by the human eye. Colours depend on the wavelength lengths, a short wavelength (the 400 nm side) looks blue and a long wavelength (the 750 nm side) looks red. (09 Oct 1997) |
| metals, light | Metals with low specific gravity, typically smaller than 5, characterised by a single valence (1, 2, or 3), a simple spectrum, strong electromotive force (positive), and colourless compounds. (12 Dec 1998) |
| minimum light | Threshold of visual sensation, the minimal light intensity evoking a visual sensation. Synonym: achromatic threshold, minimum light threshold. (05 Mar 2000) |
| minimum light threshold | Threshold of visual sensation, the minimal light intensity evoking a visual sensation. Synonym: achromatic threshold, minimum light threshold. (05 Mar 2000) |