نتایج جستجو برای: solar uv
تعداد نتایج: 187362 فیلتر نتایج به سال:
Solar ultraviolet radiation (UVR, 290-400 nm) is a crucial environmental factor in alpine lakes because of the natural increase of the UVR flux with elevation and the high water transparency of these ecosystems. The ecological importance of UVR, however, has only recently been recognized. This review, examines the general features of alpine lakes regarding UVR, summarizes what is known about th...
Pterygium is a chronic eye disease: among its recognized risk factors there is long-term exposure to ultraviolet (UV) radiation. The Sun is the main source of UV exposure: according to the World Health Organization, the Population Attributable Fraction of pterygium due to solar radiation (SR) is 42-74%. Outdoor work can deeply influence the eye exposure to solar UV rays, but, despite this, pter...
A new ultraviolet (UV)-A/B absorbing pigment with maxima at 312 and 330 nanometers from the cosmopolitan terrestrial cyanobacterium Nostoc commune is described. The pigment is found in high amounts (up to 10% of dry weight) in colonies grown under solar UV radiation but only in low concentrations in laboratory cultures illuminated by artificial light without UV. Its experimental induction by UV...
In contrast to earlier studies (Bothwell et al. 1993, 1994; DeNicola and Hoagland 1996; Kiffney et al. 1997b), Hill et al. (1997) recently concluded that there was no effect of ambient solar ultraviolet (UV) radiation on periphyton and grazers in a small Tennessee stream. These conclusions were based on the appearance that grazing pressure by pleurocerid snails (Elimia clavaeformis) controlled ...
The sun is the most important source of visible and ultraviolet (UV) radiation. Even though the distance from the sun to the Earth is large – about 150×10 km – the fluence rate of solar radiation on Earth, the solar constant, is about 1 360 W/m 2 . Approximately 40% of this radiation is reflected back into space. The remaining 60% is the driving force of all life on Earth. A number of pigments ...
While structurally complex benthic egg capsules can lower the vulnerability of gastropod embryos to a variety of environmental risks, including predation, desiccation, osmotic shock, and bacterial attack, little is known about their ability to shield embryos from ultraviolet radiation (UV) I examined the exposure of benthic egg capsules of the marine intertidal gastropod Nucella emarginata to s...
UNLABELLED The study aimed to identify endogenous lipid mediators of metabolic and inflammatory responses of human keratinocytes to solar UV irradiation. Physiologically relevant doses of solar simulated UVA+UVB were applied to human skin surface lipids (SSL) or to primary cultures of normal human epidermal keratinocytes (NHEK). The decay of photo-sensitive lipid-soluble components, alpha-tocop...
The primary motivation behind the considerable effort in studying stratospheric ozone depletion is the potential for biological consequences of increased solar UVB (280-315 nm) radiation. Yet, direct links between ozone depletion and biological impacts have been established only for organisms of Antarctic waters under the influence of the ozone "hole;" no direct evidence exists that ozone-relat...
The accumulation of ultraviolet (UV)-absorbing compounds (flavonoids and related phenylpropanoids) and the resultant decrease in epidermal UV transmittance (TUV ) are primary protective mechanisms employed by plants against potentially damaging solar UV radiation and are critical components of the overall acclimation response of plants to changing solar UV environments. Whether plants can adjus...
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