نتایج جستجو برای: sun uv radiation
تعداد نتایج: 330509 فیلتر نتایج به سال:
OBJECTIVES To establish the effect of sunless tanning products on tanning behaviors and to determine characteristics of sunless tanning product users. DESIGN A cross-sectional survey study conducted between May 30, 2007, and December 4, 2007. SETTING The Emory University campus and surrounding locations in Atlanta, Georgia. PARTICIPANTS Four hundred fifteen community and university-affili...
background: ultraviolet (uv) radiation is divided into three regions: uva, uvb, and uvc. both the quality and quantity of solar uv radiation vary with various factors including the elevation of the sun above the horizon, as well as absorption and scattering of uv photons by molecules in the atmosphere, notably ozone and clouds. it is clear that whereas a moderate amount of uv exposure is benefi...
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 ...
There is an ongoing debate how to balance between beneficial and adverse effects of UV-exposure. On the one hand, solar UV-radiation represents the most important environmental risk factor for the development of non-melanoma skin cancer. Therefore, sun protection is a key principle to prevent these malignancies, especially in risk groups. On the other hand, artificial or solar UV-radiation is r...
Adolescent organ transplant recipients have an increased risk of developing skin cancer. The aim of this study was to evaluate the technical feasibility and acceptability of short messaging service-based sun protection recommendations for adolescent patients. Sun-protective knowledge and behaviour were also evaluated using standardized questionnaires and telephone interviews. Twenty-six organ t...
The radiation emitted by the sun known as ultraviolet radiation is related to several problems that might affect the human being. Most of times, people are well warned about the effects caused to the skin by the solar radiation overexposure but not about the effects to their eyes. This work aims at developing a real time ultraviolet (UV) index meter and a series of information systems that can ...
Cutaneous human papillomavirus (HPV) has been widely detected in healthy skin. Previous studies have found that UV radiation can activate several HPV types, and a possible role for cutaneous HPV in the development of non-melanoma skin cancer has been suggested. This study investigated the prevalence and type-spectrum of cutaneous HPV in relation to UV radiation by studying forehead skin swab sa...
In the past few years, the cellular effects of ultraviolet (UV) irradiation induced in skin have become increasingly recognized. Indeed, it is now well known that UV irradiation induces structural and cellular changes in all the compartments of skin tissue. The generation of reactive oxygen species (ROS) is the first and immediate consequence of UV exposure and therefore the quantitative determ...
The effects of solar ultraviolet (UV)-B and UV-A radiation on the potential efficiency of photosystem II (PSII) in leaves of tropical plants were investigated in Panama (9 degrees N). Shade-grown tree seedlings or detached sun leaves from the outer crown of mature trees were exposed for short periods (up to 75 min) to direct sunlight filtered through plastic or glass filters that absorbed eithe...
The solar UV exposure to the eyes of humans is due to the direct and diffuse components of solar radiation. The direct ocular UV exposures to the eyes are reduced due to the natural aversion of the majority of people from looking directly at the sun. The diffuse UV is incident from all directions and as a result, it is more difficult to minimise the ocular exposure to this component of the sola...
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