نتایج جستجو برای: uv radiation
تعداد نتایج: 299907 فیلتر نتایج به سال:
BACKGROUND Although the aetiology of glioma is poorly understood, the higher incidence in males has long suggested an occupational cause. AIM To investigate possible associations between occupational exposure to ionizing, ultraviolet (UV), radiofrequency (RF) and extremely low frequency (ELF) radiation and adult glioma risk. METHODS Case-control study using histologically confirmed cases of...
The high-energy UV ray radiation on PIN Silicon photodiodes reduces the optimal parameters of these photodiodes. In this paper, by representing a model, we compare the effect of UV dose on the bright current in these two types of photodiodes and confirm the analytic relationships in order to simulate a model with the help of the Silvaco- Atlas software. In this model, Silicon photodiodes and Ga...
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...
The ultraviolet (UV) radiation present in sunlight is immune-suppressive. Recently we showed that solar-simulated UV radiation (UVA + UVB; 295-400 nm), applied after immunization, suppressed immunological memory and the elicitation of delayed-type hypersensitivity to the common opportunistic pathogen, Candida albicans. Further, we found that wavelengths in the UVA region of the solar spectrum (...
Spores and gametophytes are considered to be those life-history stages of kelps most susceptible to environmental perturbations and, in particular, to temperature and UV radiation. Microstages of Arctic (Saccharina latissima, Laminaria digitata, Alaria esculenta from Spitsbergen) and temperate kelp species (S. latissima, L. digitata, L. hyperborea from the North Sea) were exposed in 2-factorial...
An investigation was made of the variations in growth and grain yield in response to increased exposure to UV-B radiation of Japanese lowland rice (Oryza sativa L.) in a cool rice-growing region. Two cultivars, UV-resistant cv. ‘Sasanishiki’ and UV-sensitive cv. ‘Norin 1’, were examined in a lowland field at Kashimadai (37◦28′E, 141◦06′E) in Miyagi Prefecture, Japan, for four cropping seasons f...
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...
Ultraviolet (UV) radiation has both beneficial and harmful effects on the human body. Its most important beneficial effect may be vitamin D production in the skin, also known as vitamin D photosynthesis. This is of particular interest for the elderly who often show vitamin D-deficiency. Intentional UV exposure has been recommended by different institutions in order to increase vitamin D levels....
Four billion years ago, sea-level UV exposure was more than 400 times as intense as today, the dose from solar cosmic rays was five times present levels, and galactic cosmic rays accounted for only about 10% their current contribution to sea-level radiation doses. Exposure to cosmic radiation accounts for about 10% of natural background radiation exposure today and includes dose from galactic c...
Quantitative changes in foliar chemistry in response to UV-B radiation are frequently reported but less is known about the qualitative changes in putative UV-screening compounds. It has also not been conclusively shown whether qualitative differences in screening compounds or differences in localization patterns influence the sensitivity of plants to damage from UV-B radiation and there is some...
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