| PUVA | psoralen ultraviolet A-range |
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| UBI | ultraviolet blood irradiation |
| UPS | ultraviolet photoelectron spectroscopy; uninterruptible power supply; uroporphyrinogen synthetase; u... |
| UV | ultraviolet; umbilical vein; ureterovesical; Uppsala virus; urinary volume |
| UVB | ultraviolet B |
| 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) |
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| 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) |