نتایج جستجو برای: uv exposure
تعداد نتایج: 372933 فیلتر نتایج به سال:
Psoriasis is a chronic inflammatory disease involving about 2-3% of the European population. Sun exposure has a positive effect on most psoriasis lesions, but ultraviolet (UV) radiation also causes a direct DNA damage in the skin cells and comprises a carcinogenic potential. UV exposure on the skin causes a local as well as a systemic immune suppressive effect, but the relation between sun expo...
BACKGROUND There is a positive association between solar UV exposure and micronucleus frequency in peripheral blood lymphocytes (PBL) and this association may be stronger when serum vitamin D (25(OH)D) levels are insufficient (<50 nmol/L). Micronucleus formation can result from global hypomethylation of DNA repeat sequences. The aim of this analysis was to evaluate the relationship between sola...
Few studies to date have considered the responses of agriculturally important forage grasses to UV-B radiation. Yet grasses such as Lolium perenne have a wide current distribution, representing exposure to a significant variation in ambient UV-B. The current study investigated the responses of L. perenne (cv. AberDart) to a simulated latitudinal gradient of UV-B exposure, representing biologica...
Effect of enhanced ultraviolet-B radiation on pollen germination and tube growth of 19 taxa in vitro
In order to determine the response of pollen to UV-B irradiation and cumulative effects of UV-B exposure time on pollen germination and tube growth, 19 taxa of higher plants were investigated in vitro concerning the exposure of pollen grains to two levels of enhanced ultraviolet-B (UV-BBE) (280–320 nm, 350 and 500 mW/m biologically effective UV-B radiation) simulating 8 and 21% stratospheric oz...
BACKGROUND Although the incidence of non-melanoma skin cancer is increasing, there are no effective practical preventive measures other than avoiding sun exposure. OBJECTIVE To elucidate the protective effect of topical application of biologically active vitamin D3 (calcitriol) on skin cancer development caused by exposure to ultraviolet (UV). METHODS Groups of hairless mice were topically ...
Wood finishes protect the surface of wood from external agents, enhance its looks and improve its gloss (luster). On constant external exposure, UV rays gradually degrade the film coating resulting in loss of gloss. In this study, two commonly used finishes namely spirit shellac and polyurethane finish were used to investigate the pattern of loss of gloss due to UV interference. Two coatings of...
OBJECTIVES This study sought to investigate numerous reports emanating from Punta Arenas, Chile (population 110,000, latitude 53 degrees S), that associated acute ocular and dermatologic disease in humans and animals with excess ultraviolet-B (UV-B) exposure in the setting of the thinning of the ozone column. METHODS Ophthalmologic and dermatologic records in Punta Arenas were systematically ...
A simple theoretical model of liquid crystal ͑LC͒ alignment by exposure to linearly polarized ultraviolet ͑UV͒ light is proposed. The model predicts a universal relationship describing the change of the LC anchoring direction with exposure times, and the changes of polarization direction for the case of a double linearly polarized UV exposure process. This relationship is quantitatively confirmed b...
In practice, agricultural films must withstand high solar radiation, high temperature in use, mechanical stresses on the film (e.g., film tension across supports, wind), and most importantly, the antagonistic effects of agro-chemicals (pesticides, insecticides, fumigants, soil disinfectants, etc.) on the performance of the UV light stabilizers protecting the film. With pesticide usage, especial...
It is well established that exposure to ultraviolet (UV) radiation has beneficial effects in reducing prostate cancer risk. To determine if there is a correlation between UV exposure and prostate cancer risk, we assessed sun exposure in a case-control study of 182 African-American men aged 40 years and older residing in the Metropolitan Washington, DC area. Using data on cumulative exposure per...
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