نتایج جستجو برای: natural radiation

تعداد نتایج: 712214  

2014

What are x-rays and what do they do? X-rays are forms of radiant energy, like light or radio waves. Unlike light, x-rays can penetrate the body, which allows a radiologist to produce pictures of internal structures. The radiologist can view these on photographic film or on a TV or computer monitor. X-ray examinations provide valuable information about your health and play an important role in h...

2014
Zbyszek Boratyński Philipp Lehmann Tapio Mappes Timothy A. Mousseau Anders Pape Møller

Pheomelanin is a pink to red version of melanin pigment deposited in skin and hair. Due to its bright colour, pheomelanin plays a crucial function in signalling, in particular sexual signalling. However, production of pheomelanin, as opposed to its dark alternative, eumelanin, bears costs in terms of consumption of antioxidants important for protection of DNA against naturally produced reactive...

2015
Tao Zhao Sen Gong Min Hu Renbin Zhong Diwei Liu Xiaoxing Chen Ping Zhang Xinran Wang Chao Zhang Peiheng Wu Shenggang Liu

Terahertz (THz) radiation can revolutionize modern science and technology. To this date, it remains big challenges to develop intense, coherent and tunable THz radiation sources that can cover the whole THz frequency region either by means of only electronics (both vacuum electronics and semiconductor electronics) or of only photonics (lasers, for example, quantum cascade laser). Here we presen...

2006
Ragab Khir Zhongli Pan

Rice drying with infrared radiation has been investigated during recent years and showed promising potential with improved quality and energy efficiency. However, due to limited penetration capability of infrared radiation, thin layer drying may be used in infrared dryer design. The objective of this study was to study the moisture removal characteristics of thin layer rough rice heated by infr...

2011
Gerrit J. Kemerink Marij J. Frantzen Peter de Jong Joachim E. Wildberger

OBJECTIVE To compare the total work-related radiation dose in our department of radiology with the dose in Dutch residences, taking x-ray radiation, external natural radiation and radon into account. METHODS Annual doses due to exposure to x-rays and external natural radiation were derived from the measured personal dose equivalent [H(p)(10)] of 144 workers. Additionally, departmental (222)Rn...

2017
Jing Ren Liang Chen Xiaoli Jin Miaomiao Zhang Frank M. You Jirui Wang Vladimir Frenkel Xuegui Yin Eviatar Nevo Dongfa Sun Ming-Cheng Luo Junhua Peng

Whole-genome scans with large number of genetic markers provide the opportunity to investigate local adaptation in natural populations and identify candidate genes under positive selection. In the present study, adaptation genetic differentiation associated with solar radiation was investigated using 695 polymorphic SNP markers in wild emmer wheat originated in a micro-site at Yehudiyya, Israel...

Journal: :iranian journal of radiation research 0
m.b. tavakoli department of medical physics and medical engineering, school of medicine, isfahan university of medical sciences, isfahan, iran z. shahi department of medical physics and medical engineering, school of medicine, isfahan university of medical sciences, isfahan, iran

introduction: ultraviolet (uv) radiation affects human organs such as skin, eyes and immune system, as well as animals and plants. the main natural source of uv radiation is the sun. to study the effects of solar uv radiation there is a need to quantify variations of solar energy received on the earth surface at different intervals. materials and methods: to measure uv radiation a broadband fib...

Journal: :Organic & biomolecular chemistry 2009
Faïza Diaba Josep Bonjoch

The six-membered nitrogen-containing ring of the morphan scaffold, ubiquitous in natural products, is formed by an intramolecular aldol process of an aza-tethered dicarbonyl compound, leading to the first asymmetric synthesis of a morphan derivative using organocatalysis.

Journal: :Evolution; international journal of organic evolution 2003
Craig W Benkman

Knowledge of how phenotype influences fitness is necessary if we are to understand the basis of natural selection and how natural selection contributes to adaptive radiations. Here I quantify selection on a wild population of red crossbills (Loxia curvirostra complex) in the South Hills, Idaho. Bill depth is the target of selection and selection on bill depth is stabilizing. I then show how fit...

2011
M. Ragheb

Environmental radiation permeates space, air soil, and water around us. It has been naturally present since the birth of Earth about 4.65 billion years ago in a massive supernova explosion creating the heavy elements on earth and the other rocky planets Mars, Venus and Mercury. Consequently, life has evolved in the ashes and remnants of this explosion which were gravitationally grabbed in space...

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