نتایج جستجو برای: ultraviolet radiation uvr
تعداد نتایج: 268678 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...
Stratospheric ozone depletion over Antarctica is expected to continue for the next 50 years, with increases in ecologically damaging ultraviolet radiation (UVR: 290–400 nm), specifically the ultraviolet-B (UVB: 290–320 nm) portion of the spectrum. Most of coastal Antarctica is covered with 2–3 m of annual sea ice during the occurrence of the ‘‘ozone hole.’’ This physical barrier to UVR transmis...
*Correspondence: Donat-P. Häder, Neue Str. 9, D-91096 Möhrendorf, Germany e-mail: [email protected] Experiments were conducted during the Austral Summer of 2014 to determine the effects of increased nutrient input and ultraviolet radiation (UVR) on the food consumption rate (FCR) and food preference in the amphipod Amphitoe valida. We collected specimens from the Patagonian coast (Argentina), f...
The functional significance of phlorotannins as ultraviolet radiation screens in brown algae is presented. Spectral analysis of zoospore suspensions of the three Arctic Laminariales Saccorhiza dermatodea, Alaria esculenta and Laminaria digitata showed strong absorption in the UV waveband, characteristic of phlorotannins. An induction in the synthesis of the UV-absorbing compound in zoospore sus...
The exposure of outdoor workers to solar ultraviolet radiation (UVR) has been known for some time. Measurements of erythemally weighted UVR are usually related to days of exposure and to the anatomical distribution of UVR on the human body. The aim of this research is to describe the UVR exposure of workers during a strawberry production cycle in order to assess the UVR hazard and to identify t...
Cotton plants (Gossypium hirsutum L. cv 'McNair 220') at the third true leaf stage were exposed to ultraviolet radiation (UVR) for seven days and compared with controls that received only natural light. Light reflectance was spectrophotometrically measured over the 0.5-2.5 #m waveband on nonexcised leaves immediately after treatment and again seven days later. Spectral measurements were also co...
BACKGROUND Individual exposure to ultraviolet radiation (UVR) is challenging to measure, particularly for diseases with substantial latency periods between first exposure and diagnosis of outcome, such as cancer. To guide the choice of surrogates for long-term UVR exposure in epidemiologic studies, we assessed how well stable sun-related individual characteristics and environmental/meteorologic...
A potential role for endogenous proteins as sacrificial sunscreens and antioxidants in human tissues
Excessive ultraviolet radiation (UVR) exposure of the skin is associated with adverse clinical outcomes. Although both exogenous sunscreens and endogenous tissue components (including melanins and tryptophan-derived compounds) reduce UVR penetration, the role of endogenous proteins in absorbing environmental UV wavelengths is poorly defined. Having previously demonstrated that proteins which ar...
Trace gases emitted by human skin in vivo are monitored non-invasively and in real time using laser-based photoacoustic detection and proton-transfer reaction mass spectrometry. A small quartz cuvette is placed on the skin to create a headspace from which a carrier gas transports the skin emissions to the detection systems. The transparency of quartz to ultraviolet radiation (UVR) allows invest...
The net influence of ultraviolet radiation (UVR; 280-400 nm) on freshwater phytoplankton communities depends on the photon flux density, duration, and spectral quality of exposure and the UVR sensitivity of the assemblage in terms of photosynthetic impairment, biochemical composition, and nutrient assimilation mechanisms. Such effects are mitigated to varying degrees by photoacclimation and sel...
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