1,772 research outputs found
Energy Consumption and Carbon Emissions: Analysis and Prediction-The Case of Hebei Province in China
AbstractFrom the time of reform and opening up, China's rapid economic growth attracts worldwide attention, which also brings the accompanying problems that high energy consumption, high pollution and high emission are more prominent. Therefore, the low carbon economy development model has become an inevitable choice for China's sustainable economic development. However, the stage of economic development is insurmountable and the continuing growth and the disadvantaging structure of energy consumption will become a serious obstacle for China's low-carbon economy. Selecting the relevant data from 1980 to 2009, and using not only Hebei Province as its study area but also the whole country as its reference region, this paper analyzes the relationship between the changes in energy consumption structure and the carbon emissions in Hebei Province, and basing on which predicts the energy consumption and carbon emissions in the future in order to provide policy recommendations for the optimization of energy consumption structure, the upgrade of industrial structure, and the development of carbon econom
Characterization of a new feather-degrading bacterium from Calotes versicolor feces
A total of 842 spore-forming strains were isolated from 221 animal feces samples, in which a new feather-degrading bacterium identified as Bacillus sp. 50-3 based on morphological, biochemical and 16S rDNA tests was isolated from Calotes versicolor (an agamid lizard) feces. The bacterium can degrade native feather completely at mild conditions and in much shorter time (36 h) when using chicken feather as the sole carbon and nitrogen source. It presented optimum growth and maximum keratinase activity (680±25 U/ml, 36 h) at 37°C and pH 7.0 in feather meal medium. The keratinase of Bacillus sp. 50-3 was active on feather keratin as substrate and presented optimum additive quantity of 1.0% (w/v). So the high efficiency of Bacillus sp. 50-3 on feather-degradation suggested its potential use in biotechnological processes, especially in decreasing the environment pollution.Keywords: Animal feces, Bacillus, chicken feathers, keratinase, optimum conditions
Finding Efficient Collective Variables: The Case of Crystallization
Several enhanced sampling methods such as umbrella sampling or metadynamics
rely on the identification of an appropriate set of collective variables.
Recently two methods have been proposed to alleviate the task of determining
efficient collective variables. One is based on linear discriminant analysis,
the other on a variational approach to conformational dynamics, and uses
time-lagged independent component analysis. In this paper, we compare the
performance of these two approaches in the study of the homogeneous
crystallization of two simple metals. We focus on Na and Al and search for the
most efficient collective variables that can be expressed as a linear
combination of X-ray diffraction peak intensities. We find that the
performances of the two methods are very similar. However, the method based on
linear discriminant analysis, in its harmonic version, is to be preferred
because it is simpler and much less computationally demanding
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Viability of Non-Coplanar VMAT for Liver SBRT as Compared to Coplanar VMAT and Beam Orientation Optimized 4π IMRT.
PurposeThe 4π static non-coplanar radiotherapy delivery technique has demonstrated better normal tissue sparing and dose conformity than the clinically used volumetric modulated arc therapy (VMAT). It is unclear whether this is a fundamental limitation of VMAT delivery or the coplanar nature of its typical clinical plans. The dosimetry and the limits of normal tissue toxicity constrained dose escalation of coplanar VMAT, non-coplanar VMAT and 4π radiotherapy are quantified in this study.Methods and materialsClinical stereotactic body radiation therapy plans for 20 liver patients receiving 30-60 Gy using coplanar VMAT (cVMAT) were re-planned using 3-4 partial non-coplanar arcs (nVMAT) and 4π with 20 intensity-modulated non-coplanar fields. The conformity number (CN), homogeneity index (HI), 50% dose spillage volume (R50), normal liver volume receiving >15 Gy (VL>15), dose to organs at risk (OARs), and tumor control probability (TCP) were compared for all three treatment plans. The maximum tolerable dose (MTD) yielding a normal liver normal tissue control probability (NTCP) below 1%, 5%, and 10% was calculated with the Lyman-Kutcher-Burman model for each plan, as well as the resulting survival fractions at one, two, three, and four years.ResultsCompared to cVMAT, the nVMAT and 4π plans reduced VL>15 by an average of 5 cm3 and 80 cm3, respectively. 4π reduced the 50% dose spillage volume by ~23% compared to both VMAT plans, and either significantly decreased or maintained OAR doses. The 4π MTDs and survival fractions were significantly higher than both cVMAT and nVMAT (p<0.05) for all normal liver NTCP limits used in this study.ConclusionsThe 4π technique provides significantly better OAR sparing than both cVMAT and vMAT and enables more clinically relevant dose escalation for tumor local control. Therefore, despite the current accessibility of nVMAT, it is not a viable alternative to 4π for liver SBRT
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