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denoting electromagnetic radiation of wavelength shorter than that of the violet end of the spectrum, having wavelengths of 4–400 nanometers.
ultraviolet A (UVA) ultraviolet radiation with wavelengths between 320 and 400 nm, comprising over 99 per cent of such radiation that reaches the surface of the earth. Ultraviolet A enhances the harmful effects of ultraviolet B radiation and is also responsible for some photosensitivity reactions; it is used therapeutically in the treatment of a variety of skin disorders.
ultraviolet B (UVB) ultraviolet radiation with wavelengths between 290 and 320 nm, comprising less than 1 per cent of the ultraviolet radiation that reaches the earth's surface. Ultraviolet B causes sunburn and a number of damaging photochemical changes within cells, including damage to DNA, leading to premature aging of the skin, premalignant and malignant changes, and a variety of photosensitivity reactions; it is also used therapeutically for treatment of skin disorders.
ultraviolet C (UVC) ultraviolet radiation with wavelengths between 200 and 290 nm; all of this type of radiation is filtered out by the ozone layer so that none reaches the earth's surface. Ultraviolet C is germicidal and is also used in ultraviolet phototherapy.
ultraviolet rays electromagnetic radiation beyond the violet end of the visible spectrum; they are not visible to humans. They are produced by the sun but are absorbed to a large extent by particles of dust and smoke in the earth's atmosphere. They are also produced by the so-called sun lamps. They can produce sunburn and affect skin pigmentation, causing tanning. When they strike the skin surface they transform provitamin D, secreted by the glands of the skin, into vitamin D, which is then absorbed into the body. Because ultraviolet rays are capable of killing bacteria and other microorganisms, they are sometimes used to sterilize objects in specially designed cabinets, or to sterilize the air in operating rooms and other areas where destruction of bacteria is necessary.
ultraviolet therapy the employment of ultraviolet radiation in the treatment of diseases, particularly those affecting the skin. See also PUVA therapy and photochemotherapy. Among the diseases that respond to this form of therapy are acne vulgaris, psoriasis, and external ulcers.

Dosage. The dosage unit of ultraviolet radiation is expressed as minimal erythema dose (MED). Because of varying degrees of skin thickness and pigmentation, human skin varies widely in its sensitivity to ultraviolet radiation. The MED refers to the amount of radiation that will produce, within a few hours, minimal erythema (redness caused by engorgement of capillaries) in the average Caucasian skin. Dosage for individual patients is prescribed according to probable sensitivity as determined by that individual's skin type as compared to average sensitivity.
Degrees of Erythema. Minimal erythema is a first degree erythema and usually is produced after about 15 seconds of exposure to a high-pressure mercury arc in a quartz burner placed at a distance of 75 cm (30 in) from the skin. A second degree erythema results from a dose of about 2.5 MED; its effects become apparent about 4 to 6 hours after application and are followed by slight peeling of the skin. A third degree erythema is produced by about 5 MED; it may become apparent within 2 hours after application and is accompanied by edema followed by marked desquamation. A fourth degree erythema is produced by about 10 MED and is characterized by blistering.
Precautions. Ultraviolet therapy is safe only in the hands of a skilled and knowledgeable therapist. Areas of “thin skin” that may be burned more readily than that receiving treatment must be protected by wet towels or dressings. The eye is highly sensitive to ultraviolet radiation; therefore some form of protection, such as goggles, compresses, or cotton balls, should be provided for both the patient and the therapist to avoid damage to the conjunctiva and cornea.

Certain drugs, such as the sulfonamides, greatly increase sensitivity to ultraviolet radiation. All patients scheduled for this form of therapy should be questioned in regard to the medication they are taking so the dosage can be adjusted accordingly or the treatment deferred.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

ul·tra·vi·o·let (UV, uv),

Denoting electromagnetic rays at higher frequency than the violet end of the visible spectrum.
Farlex Partner Medical Dictionary © Farlex 2012


Denoting electromagnetic rays at higher frequency than the violet end of the visible spectrum.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

ultraviolet (UV) 

Radiant energy of wavelengths smaller than those of the violet end of the visible spectrum and longer than about 1 nm. The wave band comprising radiations between 315 and 380 nm is referred to as UV-A. Excessive exposure to these radiations can cause cataract. The wave band comprising radiations between 280 and 315 nm is referred to as UV-B. Excessive exposure to all these radiations can cause photokeratitis and corneal opacity, while radiations between 295 and 315 nm can cause cataract. The wave band comprising radiations between 200 and 280 nm is referred to as UV-C. Excessive exposure to these radiations can cause photokeratitis and corneal opacity. See blepharospasm; actinic keratoconjunctivitis; excimer laser; absorptive lens; nanometre; pinguecula; wavelength.
Table U1 Divisions of the ultraviolet spectrum
UV-A (near)380-315 nm
UV-B (middle)315-280 nm
UV-C (far)280-200 nm
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann
References in periodicals archive ?
Everywhere we go, from the grocery store check-out stands with their tacky women's magazines, to the mall with windows filled with mannequins and photos of young women in their underwear, to the video store with ultraviolent and pornographic movies, to the sexually graphic books many public schools are using to "teach" our kids, our sensibilities are under attack.
Here's part of the promo: "Over the past decade, Kinji Fukasaku's ultraviolent Japanese film has amassed a small, but rabid cult of fans who have traded bootleg copies on the gray market." Yep, it's that cool.
Most are around the same age as the group, enjoy skateboarding, dress similarly, and share a similarly blase attitude about the group's sometimes misogynistic and ultraviolent lyricism.
For instance, in chapter 4, "New Blood: 1970-1990," Dixon jumps straight from the films of Lucio Fulci to a brief discussion of psychopathic killers in films such as Silence of the Lambs and the ultraviolent Maniac Cop series of the 1980s and '90s, followed by a discussion of the Alien franchise, before Dixon next turns to the films of Jean Rollin.
*** Natural Born Killers (18) Oliver Stone's ultraviolent, visually exhilarating and awesomely controversial satire on media fascination with violence.
PopMatters's Chris Barsanti wrote: "Balestrini's story is a floodlike first-person narrative in which the despondent resident of a small southern Italian town tells how his community was engulfed and made utterly unlivable by an ultraviolent clan of Camorra....
London Rollergirls (LRG) is made up of four league teams, the Suffra Jets, Ultraviolent Femmes, Steam Rollers and Harbour Grudges.
Alex, protagonist/ antagonist of Burgess' seminal novel, and his peeps communicate in a trenchant combination of Nadsat - their language for an ultraviolent future - and English.
Iron Man was a sophisticated attempt to reign in this aesthetic by setting up Jeff Bridges as a kind of corrupt Kissingerian America that had to be replaced by the nicer (Obama-era?) humanitarian ultraviolent imperialism represented by Robert Downey Jr.
The debut American feature by successful Russian director Timur Bekmambetov (Night Watch and its record-smashing 2006 sequel, Day Watch), this over-the-top, ultraviolent, hyperkinetic action thriller pretty much has it all.
For the moment, only the UK, Ireland, Germany and Italy have decided to ban or block the distribution of certain ultraviolent and bloody video games, such as Manhunt 2.
Ultraviolent and anti-social, they were the video games of the McCarthy era.