نتایج جستجو برای: dual energy ray
تعداد نتایج: 1059861 فیلتر نتایج به سال:
OBJECTIVE Dual-energy x-ray absorptiometry is a low-cost, minimal radiation technique used to improve fracture prediction. Dual-energy x-ray absorptiometry machines can also capture single-energy lateral spine images, and abdominal aortic calcification (AAC) is commonly seen on these images. APPROACH AND RESULTS We investigated whether dual-energy x-ray absorptiometry-derived measures of AAC ...
There is debate over the casual factors for the rise in body weight in the UK. The present study investigates whether increases between 1986 and 2000 for men and women were a result of increases in mean total energy intake, decreases in mean physical activity levels or both. Estimates of mean total energy intake in 1986 and 2000 were derived from food availability data adjusted for wastage. Est...
Photosynthetic organisms are capable of harvesting solar energy with near unity quantum efficiency. Even more impressively, this efficiency can be regulated in response to the demands of photosynthetic reactions and the fluctuating light-levels of natural environments. We discuss the distinctive design principles through which photosynthetic light-harvesting functions. These emergent properties...
Introduction Flexibility is needed in planning rations for livestock to meet the fluctuations in the economic situation, highlighted for instance by the recent scarcity and high price of protein-rich foods. Tables of requirements tend to treat protein and energy separately, whereas their joint effects on production are becoming more apparent. The ‘requirements’ concept could with advantage incl...
[This corrects the article DOI: 10.1371/journal.pone.0162164.].
1 International Research Center for Renewable Energy, State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China 2 Joint Center for Artificial Photosynthesis, California Institute of Technology, Pasadena, CA 91125, USA 3 Centre for Clean Environment and Energy, Environmental Futures Centre, Griffith University, Gold Coast, QLD 4215, Aus...
Motivated by the large effect of turbulent drag reduction by minute concentrations of polymers, we study the effects of a weakly space-dependent viscosity on the stability of hydrodynamic flows. In a recent paper [Phys. Rev. Lett. 87, 174501, (2001)], we exposed the crucial role played by a localized region where the energy of fluctuations is produced by interactions with the mean flow (the "cr...
The quantized Dirac field is known, by a result of Fewster and Verch, to satisfy a Quantum Weak Energy Inequality (QWEI) on its averaged energy density along time-like curves in arbitrary four-dimensional globally hyperbolic spacetimes. However, this result does not provide an explicit form for the bound. By adapting ideas from the earlier work, we give a simplified derivation of a QWEI for the...
In this work, total smooth air-water interfacial areas were measured for a series of nine natural and model sandy porous media as a function of water saturation using synchrotron X-ray microtomography. Interfacial areas decreased linearly with water satuation, while the estimated maximum interfacial area compared favorably to the media geometric surface areas. Importantly, relative interfacial ...
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