نتایج جستجو برای: absorbed fraction

تعداد نتایج: 170740  

Journal: :Journal of environmental radioactivity 2002
D Nikezic A K M M Haque K N Yu

The present work aims to develop a semi-analytical method to calculate the absorbed dose delivered by alpha particles in a cylindrical geometry. This method will be employed to reproduce the dose conversion coefficients or absorbed fraction of alpha particles in sensitive cells of the tracheobronchial tree obtained by NRC and ICRP, respectively. The difference caused by using water stopping pow...

2013
Changwei Tan Arindam Samanta Xiuliang Jin Lu Tong Chang Ma Wenshan Guo Yuri Knyazikhin Ranga B. Myneni

The fraction of photosynthetically active radiation (FPAR) absorbed by vegetation – a key parameter in crop biomass and yields as well as net primary productivity models – is critical to guiding crop management activities. However, accurate and reliable estimation of FPAR is often hindered by a paucity of good field-based spectral data, especially for corn crops. Here, we investigate the relati...

2001
R. B. Myneni S. Hoffman Y. Knyazikhin J. L. Privette Y. Wang P. Votava

An algorithm based on the physics of radiative transfer in vegetation canopies for the retrieval of vegetation green leaf area index (LAI) and fraction of absorbed photosynthetically active radiation (FPAR) from surface reflectances was developed and implemented for operational processing prior to the launch of the moderate resolution imaging spectroradiometer (MODIS) aboard the TERRA platform ...

2011
M. Weiss F. Baret

This paper reviews the several methods available for estimating the fAPAR, both at local and large scale. The fAPAR definition is first discussed with regards to the directionality of the incident radiation. Then, the several techniques to estimate fAPAR from local ground measurements are reviewed with emphasis on the sampling strategy. We then describe methodologies to upscale fAPAR measuremen...

Journal: :Bio-medical materials and engineering 2014
Chenyin Wang Alex Avdeef Wen Zhang Kin Y Tam

The purpose of this study is to predict human jejunal permeability (P(eff)) and fraction absorbed in human (%F(a)) for a group of antibacterial fluoroquinolones (FQs), by using a biophysical model based on measured Caco-2 permeability. The predicted P(eff) (in 10(-4) cm · s(-1) units) ranged from 0.7 (norfloxacin) to 4.5 (pefloxacin). The calculated %F(a) for norfloxacin = 51% (lit. 35%) and fo...

2005
Andrés Viña Anatoly A. Gitelson

[1] The fraction of absorbed photosynthetically active radiation, fAPAR, is an important biophysical characteristic in models of gas exchange between the terrestrial boundary layer and the atmosphere, as well as in the analysis of vegetation productivity. Synoptic estimation of fAPAR has been performed by using NDVI as a linear proxy of fAPAR, despite the saturation of NDVI at fAPAR beyond 0.7....

2015
Mohammad Taghi Bahreyni Toossi Eftekhar Rajab Bolookat Raham Salek Mohsen Layegh

Introduction Radiotherapy is regarded as the first treatment of choice for nasopharyngeal carcinoma. Despite the advantages of radiotherapy, patients may suffer from a wide range of side-effects due to the presence of many sensitive normal tissues in these regions. If the absorbed dose exceeds the tolerance level in parotid glands and the spinal cord, myelopathy, Lhermitte's sign and xerostomia...

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