نتایج جستجو برای: natural radiation
تعداد نتایج: 712214 فیلتر نتایج به سال:
The effects of natural variation in background radioactivity on humans, animals and other organisms.
Natural levels of radioactivity on the Earth vary by more than a thousand-fold; this spatial heterogeneity may suffice to create heterogeneous effects on physiology, mutation and selection. We review the literature on the relationship between variation in natural levels of radioactivity and evolution. First, we consider the effects of natural levels of radiation on mutations, DNA repair and gen...
Generation of subpicosecond terahertz pulses is observed when graphite surfaces are illuminated with femtosecond near-infrared laser pulses. The nonlinear optical generation of THz pulses from graphite is unexpected since, in principle, the material possesses a centre of inversion symmetry. Experiments with highly oriented pyrolytic graphite crystals suggest that the THz radiation is generated ...
the present study has tried to accomplish an analysis of margaret atwood’s novels oryx and crake, and the year of the flood in the light of posthuman and cyborg theories. considering posthumanism as a critical reading of some notions of humanism focus of which in this thesis has been identity, new definitions for humanity and human identity are formed. haraway’s cyborg, as one possible new figu...
Aim of this study was to monitor the solar ultraviolet-B intensity and to compare the phototoxic effect of different intensity of natural and artificial ultraviolet-B on human red blood cells in presence of compounds as riboflavin and chloroquine. Photohemolysis of erythrocytes was studied under natural solar radiation and artificial ultraviolet-B radiation of 312 nm. Monitoring of solar ultrav...
Introduction Iron ore is one of the most important natural raw materials that is widely used for manufacturing iron and steel. This type of ore contains various amounts of radionuclides; thus, exposing workers handling their extraction, transportation, and processing to radiation. Materials and Methods In this study, 12 ore samples (each mass weighing about 2 kg) were collected from the iron or...
while a crystalline material is heated from room temperature to around 500°c, a weak but measurable light will be emitted. this light is known as thermoluminescence (tl) and is based on storage of energy from ionizing radiation in many naturally occurring tl minerals, including quartz and feldspar. the source of radiation is the radioactive materials such as uranium, thorium, potassium and cosm...
the existence of a high natural radiation area in the northern part of iran (ramsar) is proved. ra 226 in soil is measured. the results are: minimum 23.5 pci/g and maximum 999 pci/g soil. environmental radioactivity is from 0.1 to 5 mr/h.
Since exposure to irradiation in radiotherapy or unwanted radiation, induces side effects to health, it is important to makear effort to protect humans against side effects induced by irradiation. In these cases, radioprotective drugs could be used to reduce or delay the side effects and the mortality induced by irradiation. Although, thiol compounds were early compounds in these categories, ...
background: human is exposed to radiation in their environment with or without their consent and the exposure to natural background radiation is an unpreventable event on earth. materials and methods: an in situ assessment of the indoor and outdoor background radiation in akwanga and keffi towns of nasarawa state nigeria was carried out using a halogen-quenched geiger muller (gm) detector (insp...
Background: Ramsar (Mazandran province) is known for its extremely high levels of natural background radiation. Although no excess cancer rate is reported in these areas by epidemiological studies, the study of tumor markers in the inhabitants of these areas may shed some light on the impact of high levels of background radiation on cancer induction. Materials and Methods: The level of backgrou...
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