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A regularization scheme for explicit level-set XFEM topology optimization

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Frontiers of Mechanical Engineering 2019年第2期14卷 153-170页

作者： Markus j.GEISS jorge L.BARRERA Narasimha BODDETI Kurt MAUTE Ann and h.j.Smead Department of Aerospace Engineering Sciences University of Colorado at BoulderBoulderCO 80309-0429USA Singapore University of Technology and Design SUTD Digital Manufacturing and Design CentreSingapore 487372Singapore

Regularization of the level-set(LS)field is a critical part of LS-based topology optimization(TO)*** this is achieved by advancing the LS field through the solution of a hamilton-jacobi equation combined with a reinitialization *** approach,however,may limit the maximum step size and introduces discontinuities in the design ***,energy functionals and intermediate LS value penalizations have been *** paper introduces a novel LS regularization approach based on a signed distance field(SDF)which is applicable to explicit LSbased *** SDF is obtained using the heat method(hM)and is reconstructed for every design in the optimization *** governing equations of the hM,as well as the ones describing the physical response of the system of interest,are discretized by the extended finite element method(XFEM).Numerical examples for pro?blems modeled by linear elasticity,nonlinear hyperelasticity and the incompressible Navier-Stokes equations in two and three dimensions are presented to show the applicability of the proposed scheme to a broad range of design optimization problems.

关键词： level-set regularization explicit level-sets XFEM CutFEM topology optimization heat method signed distance field nonlinear structural mechanics fluid mechanics

Glyphosate-Resistant Giant Ragweed(Ambrosia trifida L.):2,4-D Dose Response and Control with Postemergence herbicides in Soybean

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American journal of Plant Sciences 2013年第9期4卷 1790-1798页

作者： joanna Follings Nader Soltani Darren E.Robinson Francois j.Tardif Mark B.Lawton Peter h.Sikkema University of Guelph Ridgetown Campus RidgetownCanada University of Guelph GuelphCanada Monsanto Canada GuelphCanada

Glyphosate resistant giant ragweed is an increasing problem in glyphosate resistant cropping systems in southwestern Ontario. The postemergence herbicides registered for use in soybean in Ontario do not provide consistent control of glyphosate resistant giant ragweed. There is limited research on the lowest effective rate of 2,4-D for the control of glyphosate resistant giant ragweed. Consequently, the objectives of this study were a) to determine the efficacy of herbicides applied postemergence for the control of glyphosate resistant giant ragweed in glyphosate resistant soybean, and b) to determine the lowest effective rate of 2,4-D for the control of glyphosate-resistant giant ragweed. Ten postemergence herbicide combinations and seven rates of 2,4-D were evaluated in field studies conducted in 2011 and 2012 at six locations confirmed with glyphosate-resistant giant ragweed. The post emergence herbicides evaluated did not provide acceptable/consistent control. Of the herbicides evaluated, glyphosate plus cloransulam-methyl provided 26% to 70% control 8 WAA of glyphosate resistant giant ragweed, which was the best of the herbicides combinations evaluated. The doses of 2,4-D required to reduce giant ragweed shoot dry weight by 50, 80 and 95% were 142, 310 and 1048 g a.e. ha-1, respectively.

关键词： Glyphosate Resistance Multiple herbicide-Resistant Crops Preplant herbicides Postemergence herbicides

Current Injection Provokes Rapid Expansion of the Guard Cell Cytosolic Volume and Triggers Ca^2＋ Signals

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Molecular Plant 2016年第3期9卷 471-480页

作者： Lena j. Voss Rainer hedrich M. Rob G. Roelfsema Molecular Plant Physiology and Biophysics Julius-von-Sachs Institute for Biosciences Biocenter Werzburg University Julius-von-Sachs-Platz 2 97082 Werzburg Germany

high-resolution microscopy opens the door for detailed single-cell studies with fluorescent reporter dyes and proteins. We used a confocal spinning disc microscope to monitor fluorescent dyes and the fluorescent protein Venus in tobacco and Arabidopsis guard cells. Multi-barreled microelectrodes were used to inject dyes and apply voltage pulses, which provoke transient rises in the cytosolic Ca^2＋ level. Voltage pulses also caused changes in the distribution of Lucifer Yellow and Venus, which pointed to a reversible increase of guard cell cytosolic volume. The dynamic cytosolic volume changes turned out to be provoked by current injection of ions. A reduction of the clamp current, by blocking K^＋ uptake channels with Cs^＋, strongly suppressed the cytosolic volume changes. Cs^＋ not only inhibited the expansion of the cytosol, but also inhibited hyperpolarization-induced elevations of the cytosolic Ca^2＋ concentration. A complete loss of voltage-induced Ca^2＋ signals occurred when Ca^2＋-permeable plasma membrane channels were simultaneously blocked with La^3＋. This shows that two mechanisms cause hyperpolarization-induced elevation of the cytosolic Ca^2＋-concentration：（i） activation of voltage-dependent Ca^2＋-permeable channels, （ii） osmotically induced expansion of the cytosol, which leads to a release of Ca^2＋ from intracellular stores.

关键词： guard cell cytosolic Ca^2+ cytosolic volume voltage clamp current injection ion channel

Analysis of the Driving Force of hydrodynamics in Lake Naivasha, Kenya

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Open journal of Modern hydrology 2015年第4期5卷 95-104页

作者： jane N. Ndungu Wenlong Chen Denie C. M. Augustijn Suzanne j. M. h. hulscher MEEP Kenya Marine and Fisheries Research Institute Mombasa Kenya Twente Water Centre University of Twente Enschede The Netherlands

The hydrodynamics in Lake Naivasha, a shallow endorheic lake, are simulated using the Delft3D Flow Module to investigate the major driving forces of hydrodynamics in the lake. The results showed wind as the major forcing. The shallow zones of the lake showed currents movement in the same direction as the wind while the deep zones showed currents movements against the wind direction. These findings were confirmed and further explained using an idealized model. Limited exchange between the Crescent Lake (crater lake which is temporally separated from the lake during low water levels) and the main lake was observed. These findings can explain the spatial variability of the water quality in the lake. Similar studies could be used in exploratory studies of the spatial-temporal variability in water quality in other shallow water systems.

关键词： hydrodynamics Water Quality Shallow Lakes Wind-Driven Currents Lake Naivasha

3eciphering the protein-DNA code of bacteria Ninged helix-turn-helix transcription factors

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Frontiers of Electrical and Electronic Engineering in China 2018年第1期6卷 68-84页

作者： Adam P. joyce james j. havranek Program in Developmental Regenerative and Stem Cell Biology Washington University in St. Louis St. Louis MO 63110 USA Department of Biochemistry and Molecular Biophysics Washington University in St. Louis St. Louis MO 63110 USA

Background： Sequence-specific binding by transcription factors （TFs） plays a significant role in the selection and regulation of target genes. At the protein：DNA interface, amino acid side-chains construct a diverse physicochemical network of specific and non-specific interactions, and seemingly subtle changes in amino acid identity at certain positions may dramatically impact TF：DNA binding. Variation of these specificity-determining residues （SDRs） is a major mechanism of functional divergence between TFs with strong structural or sequence homology. Methods： In this study, we employed a combination of high-throughput specificity profiling by SELEX and Spec-seq, structural modeling, and evolutionary analysis to probe the binding preferences of winged helix-turn-helix TFs belonging to the OmpR sub-family in Escherichia coil Results： We found that E. coli OmpR paralogs recognize tandem, variably spaced repeats composed of＂GT-A＂ or ＂GCT＂-containing half-sites. Some divergent sequence preferences observed within the ＂GT-A＂ mode correlate with amino acid similarity; conversely, ＂GCT＂-based motifs were observed for a subset of paralogs with low sequence homology. Direct specificity profiling of a subset of OmpR homologues （CpxR, RstA, and OmpR） as well as predicted ＂SDR-swap＂ variants revealed that individual SDRs may impact sequence preferences locally through direct contact with DNA bases or distally via the DNA backbone. Conclusions： Overall, our work provides evidence for a common structural code for sequence-specific whTh：DNA interactions, and demonstrates that surprisingly modest residue changes can enable recognition of highly divergent sequence motifs. Further examination of SDR predictions will likely reveal additional mechanisms controlling the evolutionary divergence of this important class of transcriptional regulators.

关键词： transcription factor SELEX winged helix-turn-helix specificity detenlainants two-component signaling

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物理常数

物理常数

Vagal Nerve Stimulation May Be a Potentially Beneficial Treatment for Acute Myocardial Ischemia

1963年

作者：（英）W.h.恰而斯（Childs W.h.j.）翟佩英李华海译

来源：汇雅图书（南通市图书馆... 评论

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麻醉与监护论坛 2010年第5期17卷 332-334页

作者： j. Xiong F. S. Xue Y. j. Yuan Q. Wang S. Li j. h. Liu X. Liao Y. M. Zhang Department of Anesthesiology Plastic Surgery Hospital Chinese Academy of Medical Sciences and Peking Union Medical College Beijing 100144 China

Myocardial ischcmia reperfusion injury is an inflammatory process which is characterized with augmenting production and release of proinflammatory cytokines. Although ischemia pre-and postconditioniug can protect myocardium against iscbemia reperfusion injury, existence of some limitations restricts their clinical application widely. Vagus nerve stimulation has been identified with ability to inhibit release of proinflammatory cytokines and to provide other benefits to myocardial ischemia reperfusion injury. Moreover, vagus nerve stimulation has been already used clinically in patients with neuropsychiatric disorders and chronic advanced heart failure. Thus we consider that vagus nerve stimulation may be an effective adjunct treatment attenuating myocardial ischemia reperfusion injury prior to hospital arrival or percutaneous coronary intervention.

关键词：麻醉学原理局部麻醉全身麻醉监护

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IVIM提高术前评估肝细胞癌微血管侵犯

国际医学放射学杂志 2019年第6期 751-752页

作者： Y.Wei Z.X.huang h.h.Tang L.P.Deng Y.Yuan j.X.Li 袁源 Department of Radiology West China Hospital Sichuan University

摘要目的前瞻性评估体素内不相干运动(IVIM)和常规影像特征在肝细胞癌(hCC)病人术前预测微血管侵犯(MVI)中的潜在作用。方法本研究获得了机构伦理委员会

关键词：微血管侵犯肝细胞癌术前评估

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青藏高原东坡降水的同位素高程梯度

中国科学：地球科学 2022年第11期52卷 2193-2205页

作者：李捷庞忠和北京师范大学水科学研究院地下水污染控制与修复教育工程研究中心北京100875 中国科学院地质与地球物理研究所页岩气与地质工程重点实验室北京100029 中国科学院地球科学创新研究院北京100029 中国科学院大学北京100049 南京大学关键地球物质循环前沿科学中心南京210008

青藏高原(TP)受不同来源的水汽影响,降水同位素高程梯度在不同坡向可能存在差异.本研究系统地监测和模拟了青藏高原东坡降水中稳定同位素的高程效应,共采集了265件水样进行稳定同位素(δ~2h和δO)测试,其中70件是逐次降水样品,195个是... 详细信息

青藏高原(TP)受不同来源的水汽影响,降水同位素高程梯度在不同坡向可能存在差异.本研究系统地监测和模拟了青藏高原东坡降水中稳定同位素的高程效应,共采集了265件水样进行稳定同位素(δ~2h和δO)测试,其中70件是逐次降水样品,195个是用于比较的地表水样品.山巅湖泊水样经过蒸发校正后用来代表当地降水的平均同位素组成.结果表明,青藏高原东部边缘区的高程梯度为-4.2‰km^(-1)(R^(2)=0.93),瑞利分馏模型进一步证实了该高程梯度.与青藏高原不同坡向及腹地相比,这是迄今为止得到的高程梯度最大值.青藏高原腹地降水同位素高程梯度较小,可能是高原腹地的水汽再循环所致.本文结果还表明采用河水样本构建高程梯度具有显著的局限性.

关键词：降水同位素高程梯度稳定同位素瑞利分馏水汽再循环青藏高原