6,132 research outputs found

    Aspect ratio dependence of heat transport by turbulent Rayleigh-B\'{e}nard convection in rectangular cells

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    We report high-precision measurements of the Nusselt number NuNu as a function of the Rayleigh number RaRa in water-filled rectangular Rayleigh-B\'{e}nard convection cells. The horizontal length LL and width WW of the cells are 50.0 cm and 15.0 cm, respectively, and the heights H=49.9H=49.9, 25.0, 12.5, 6.9, 3.5, and 2.4 cm, corresponding to the aspect ratios (ΓxL/H,ΓyW/H)=(1,0.3)(\Gamma_x\equiv L/H,\Gamma_y\equiv W/H)=(1,0.3), (2,0.6)(2,0.6), (4,1.2)(4,1.2), (7.3,2.2)(7.3,2.2), (14.3,4.3)(14.3,4.3), and (20.8,6.3)(20.8,6.3). The measurements were carried out over the Rayleigh number range 6×105Ra10116\times10^5\lesssim Ra\lesssim10^{11} and the Prandtl number range 5.2Pr75.2\lesssim Pr\lesssim7. Our results show that for rectangular geometry turbulent heat transport is independent of the cells' aspect ratios and hence is insensitive to the nature and structures of the large-scale mean flows of the system. This is slightly different from the observations in cylindrical cells where NuNu is found to be in general a decreasing function of Γ\Gamma, at least for Γ=1\Gamma=1 and larger. Such a difference is probably a manifestation of the finite plate conductivity effect. Corrections for the influence of the finite conductivity of the top and bottom plates are made to obtain the estimates of NuNu_{\infty} for plates with perfect conductivity. The local scaling exponents βl\beta_l of NuRaβlNu_{\infty}\sim Ra^{\beta_l} are calculated and found to increase from 0.243 at Ra9×105Ra\simeq9\times10^5 to 0.327 at Ra4×1010Ra\simeq4\times10^{10}.Comment: 15 pages, 7 figures, Accepted by Journal of Fluid Mechanic

    3-(4-Methoxy­phen­yl)-1-(2-nitrophen­yl)prop-2-en-1-one

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    The title compound, C16H13NO4, was prepared from 2-nitrylhypnone [systematic name: 1-(2-nitrophenyl)ethanone] and 4-methoxy­benzophenone by a Claisen–Schmidt condensation. The dihedral angle formed by the two benzene rings is 80.73 (2). The crystal packing is stabilized by inter­molecular C—H⋯O hydrogen bonds

    Mtmr8 is essential for vasculature development in zebrafish embryos

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    <p>Abstract</p> <p>Background</p> <p>Embryonic morphogenesis of vascular and muscular systems is tightly coordinated, and a functional cooperation of Mtmr8 with PI3K in actin filament modeling and muscle development has been revealed in zebrafish. Here, we attempt to explore the function of Mtmr8 in vasculature development parallel to its function in muscle development.</p> <p>Results</p> <p>During early stage of somitogenesis, <it>mtmr8 </it>expression was detected in both somitic mesodem and ventral mesoderm. Knockdown of <it>mtmr8 </it>by morpholino impairs arterial endothelial marker expression, and results in endothelial cell reduction and vasculogenesis defects, such as retardation in intersegmental vessel development and interruption of trunk dorsal aorta. Moreover, <it>mtmr8 </it>morphants show loss of arterial endothelial cell identity in dorsal aorta, which is effectively rescued by low concentration of PI3K inhibitor, and by over-expression of <it>dnPKA </it>mRNA or <it>vegf </it>mRNA. Interestingly, <it>mtmr8 </it>expression is up-regulated when zebrafish embryos are treated with specific inhibitor of Hedgehog pathway that abolishes arterial marker expression.</p> <p>Conclusion</p> <p>These data indicate that Mtmr8 is essential for vasculature development in zebrafish embryos, and may play a role in arterial specification through repressing PI3K activity. It is suggested that Mtmr8 should represent a novel element of the Hedgehog/PI3K/VEGF signaling cascade that controls arterial specification.</p

    Trace initial interaction from final state observable in relativistic heavy ion collisions

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    In order to trace the initial interaction in ultra-relativistic heavy ion collision in all azimuthal directions, two azimuthal multiplicity-correlation patterns -- neighboring and fixed-to-arbitrary angular-bin correlation patterns -- are suggested. From the simulation of Au + Au collisions at 200 GeV by using the Monte Carlo models RQMD with hadron re-scattering and AMPT with and without string melting, we observe that the correlation patterns change gradually from out-of-plane preferential one to in-plane preferential one when the centrality of collision shifts from central to peripheral, meanwhile the anisotropic collective flow v_2 keeps positive in all cases. This regularity is found to be model and collision energy independent. The physics behind the two opposite trends of correlation patterns, in particular, the presence of out-of-plane correlation patterns at RHIC energy, are discussed.Comment: 5pages, 4figure

    Assessment of Long-Term Watershed Management on Reservoir Phosphorus Concentrations and Export Fluxes.

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    Source water nutrient management to prevent eutrophication requires critical strategies to reduce watershed phosphorus (P) loadings. Shanxi Drinking-Water Source Area (SDWSA) in eastern China experienced severe water quality deterioration before 2010, but showed considerable improvement following application of several watershed management actions to reduce P. This paper assessed the changes in total phosphorus (TP) concentrations and fluxes at the SDWSA outlet relative to watershed anthropogenic P sources during 2005⁻2016. Overall anthropogenic P inputs decreased by 21.5% over the study period. Domestic sewage, livestock, and fertilizer accounted for (mean ± SD) 18.4 ± 0.6%, 30.1 ± 1.9%, and 51.5 ± 1.5% of total anthropogenic P inputs during 2005⁻2010, compared to 24.3 ± 2.7%, 8.8 ± 10.7%, and 66.9 ± 8.0% for the 2011⁻2016 period, respectively. Annual average TP concentrations in SDWSA decreased from 0.041 ± 0.019 mg/L in 2009 to 0.025 ± 0.013 mg/L in 2016, a total decrease of 38.2%. Annual P flux exported from SDWSA decreased from 0.46 ± 0.04 kg P/(ha·a) in 2010 to 0.25 ± 0.02 kg P/(ha·a) in 2016, a decrease of 44.9%. The success in reducing TP concentrations was mainly due to the development of domestic sewage/refuse collection/treatment and improved livestock management. These P management practices have prevented harmful algal blooms, providing for safe drinking water

    Traditional Chinese medicine combined with hormone therapy to treat premature ovarian failure: a meta-analysis of randomized controlled trials

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    Background: This meta-analysis aimed to provide critically estimated evidence for the advantages and disadvantages of Chinese herbal medicines used for premature ovarian failure (POF), which could provide suggestions for rational treatments.Materials and Methods: The databases searched included MEDLINE, EMBASE, CNKI, VIP, China Dissertation Database, China Important Conference Papers Database, and online clinical trial registry websites. Published and unpublished randomized controlled trials of traditional Chinese medicine (TCM) combined with hormone therapy (HT) and HT alone for POF were assessed up to December 30, 2015. Two authors extracted data and assessed trial quality independently using Cochrane systematic review methods. Meta-analysis was used to quantitatively describe serum hormone levels and Kupperman scores associated with perimenopause symptoms.Results: Seventeen randomized controlled trials involving 1352 participants were selected. Compared with HT alone, although no significant effects were observed in the levels of luteinizing hormone, therapy with TCM combined with HT compared to HT alone effectively altered serum hormone levels of follicle stimulating hormone (P&lt;0.01) and estradiol (P &lt; 0.01), and improved Kupperman index scores (P&lt; 0.01).Conclusions: The reported favorable effects of TCM combined with HT for treating POF patients are better than HT alone.However,the beneficial effects derived from this combination therapy cannot be viewed conclusive.In order to better support the clinical use, more rigorously designed trials are required to provide.Keywords: Traditional Chinese medicine, Hormone therapy, Premature ovarian failure, Meta-analysi

    Investigation of Carbon Tax Pilot in YRD Urban Agglomerations—Analysis and Application of a Novel ESER System with Carbon Tax Constraints

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    AbstractThis paper attempts to explore the dynamic behavior of energy-saving and emission-reduction (ESER) system in Yangtze River Delta (YRD) urban agglomerations, which has not yet been reported in present literature. The novel YRD urban agglomerations carbon tax attractor is achieved. A scenario study is carried out. The results show that, the ESER system in YRD urban agglomerations is superior to the average case in China, in which the impacts on economic growth are almost the same. The economic property of YRD urban agglomerations is the main cause why the ESER system of YRD urban agglomerations being superior
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