نتایج جستجو برای: ultraviolet radiation uvr

تعداد نتایج: 268678  

Journal: :Journal of photochemistry and photobiology. B, Biology 2001
R Sommaruga

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...

2004
Michael P. Lesser Miles D. Lamare Michael F. Barker

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...

2014
Macarena S. Valiñas Paula Bermejo Lara Galbán Luciana Laborda Donat-P. Häder Virginia E. Villafañe E. Walter Helbling

*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...

2006
Michael Y. Roleda Margaret N. Clayton Christian Wiencke

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...

Journal: :Journal of agricultural safety and health 2014
G Nardini D Neri M Paroncini

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...

2002
HAROLD W. GAUSMAN DAVID E. ESCOBAR D. E. ESCOBAR

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...

2013
Elizabeth Khaykin Cahoon David C. Wheeler Michael G. Kimlin Richard K. Kwok Bruce H. Alexander Mark P. Little Martha S. Linet Daryl Michal Freedman

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...

2015
Sarah A. Hibbert Rachel E.B. Watson Neil K. Gibbs Patrick Costello Clair Baldock Anthony S. Weiss Christopher E.M. Griffiths Michael J. Sherratt

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...

Journal: :Physiological measurement 2006
B W M Moeskops M M L Steeghs K van Swam S M Cristescu P T J Scheepers F J M Harren

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...

Journal: :Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology 2009
Joel W Harrison Ralph E H Smith

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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