| UPS | ultraviolet photoelectron spectroscopy; uninterruptible power supply; uroporphyrinogen synthetase; u... |
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| UV | ultraviolet; umbilical vein; ureterovesical; Uppsala virus; urinary volume |
| UVB | ultraviolet B |
| UVER | ultraviolet-enhanced reactivation |
| UVI | ultraviolet irradiation |
| spectrophotometry, ultraviolet | Determination of the spectra of ultraviolet absorption by specific molecules in gases or liquids, for example cl2, so2, no2, cs2, ozone, mercury vapor, and various unsaturated compounds. (12 Dec 1998) |
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| intravital ultraviolet | Having wavelengths of 3900 to 3200 A |
| extravital ultraviolet | Having wavelengths of 2900 to 1850 A |
| ultraviolet | <physics> Continuous spectrum beyond the violet end of the visible spectrum (wavelength less than 400nm) and above the X-ray wavelengths (greater than 5 nm). Glass absorbs UV, so optical systems at these wavelengths have to be of quartz. Nucleic acids absorb UV most strongly at around 260nm and this is the wavelength most likely to cause mutational damage (by the formation of thymine dimers). It is the UV component of sunlight that causes actinic keratoses to form in skin, but that is also required for Vitamin D synthesis. (18 Nov 1997) |
| ultraviolet A | Ultraviolet radiation from 320 to 400 nm that causes skin tanning but is very weakly sunburn-producing and carcinogenic. (05 Mar 2000) |
| ultraviolet B | Ultraviolet radiation from 290 to 320 nm that most effectively causes sunburning and tanning; excessive UVB exposure is a cause of cancer of fair skin. (05 Mar 2000) |
| ultraviolet C | Ultraviolet radiation from 200 to 290 nm; UVC in sunlight does not reach the surface of the earth; germicidal and mercury arc lamps may cause sunburn and photokeratitis. (05 Mar 2000) |
| ultraviolet keratoconjunctivitis | Acute keratoconjunctivitis resulting from exposure to intense ultraviolet irradiation. Synonym: actinic conjunctivitis, arc-flash conjunctivitis, flash keratoconjunctivitis, ophthalmia nivalis, snow conjunctivitis, welder's conjunctivitis. (05 Mar 2000) |
| ultraviolet lamp | A lamp that emits rays in the ultraviolet band of the spectrum. See: ultraviolet. (05 Mar 2000) |
| ultraviolet microscope | <instrument> A microscope having optics of quartz and fluorite that allow transmission of light waves shorter than those of the visible spectrum, i.e., below 400 nm; the image is made visible by photography, fluorescence of special glasses, or television; in a scanning instrument the receptor is a multiplier phototube. (05 Mar 2000) |
| ultraviolet radiation | <physics> Invisible light, next to visible light in the electromagnetic spectrum. The most common source of ultraviolet radiation is the sun. Acronym: UV (16 Dec 1997) |
| ultraviolet rays | That portion of the electromagnetic spectrum immediately below the visible range and extending into the X-ray frequencies. The longer wavelengths (near-uv or biotic or vital rays) are necessary for the endogenous synthesis of vitamin d and are also called antirachitic rays; the shorter, ionizing wavelengths (far-uv or abiotic or extravital rays) are viricidal, bactericidal, mutagenic, and carcinogenic and are used as disinfectants. (12 Dec 1998) |
| ultraviolet spectrum | The electromagnetic spectrum beyond the violet end of the visible spectrum. (05 Mar 2000) |
| ultraviolet therapy | The use of ultraviolet electromagnetic radiation in the treatment of disease, usually of the skin. This is the part of the sun's spectrum that causes sunburn and tanning. Ultraviolet a, used in puva, is closer to visible light and less damaging than ultraviolet b, which is ionizing. (12 Dec 1998) |