检索结果-南通市图书馆

Science China(Life Sciences) 2019年第10期62卷 1375-1380页

作者： Elizabeth A. Hines Mary-Kayt N. Jones Julie F. Harvey chad perlyn David M. Ornitz Xin Sun Jamie M. Verheyden Laboratory of Genetics University of WisconsinMadisonWI 53706USA Department of Surgery Florida International University College of MedicineMiamiFL 33199USA Department of Developmental Biology Washington University School of MedicineSt. LouisMO 63110USA Department of Pediatrics University of California-San DiegoLa JollaCA 92093USA

Crouzon syndrome is the result of a gain-of-function point mutation in FGFR2. Mimicking the human mutation, a mouse model of Crouzon syndrome(Fgfr2342Y) recapitulates patient deformities, including failed tracheal cartilage segmentation, resulting in a cartilaginous sleeve in the homozygous mutants. We found that the Fgfr2C342Y/C^342Y mutants exhibited an increase in chondrocytes prior to segmentation. This increase is due at least in part to over proliferation. Genetic ablation of chondrocytes in the mutant led to restoration of segmentation in the lateral but not central portion of the trachea. These results suggest that in the Fgfr2C342Y/C342Y mutants, increased cartilage cell proliferation precedes and contributes to the disruption of cartilage segmentation in the developing trachea.

关键词： trachea lung mouse development

A sugary addition to the urea cycle

在线全文

学校读者我要写书评

暂无评论

Journal of Molecular Cell Biology 2022年第4期14卷 1-2页

作者： chad Slawson Department of Biochemistry and Molecular Biology University of Kansas Medical CenterKansas CityKS 66160USA

In a recent publication,Wu et al.(2022)asked a simple premise:how does aging impact O-GlcNAcylation in the liver?what they discovered,however,requires us to ask a more fundamental question:how does aging alter nutrientsensing pathways and the messages they communicate?In order to answer this question,we must remember that nutrient sensing is hinged on_posttranslational modifications(PTMs)and the availability of nutrients necessaryfor producing PTM *** monophosphate(AMP)-regulated protein kinase,which is sensitive to the ratio of AMP to adenosine triphosphate,and mammalian target of rapamycin,an anabolic kinase regulated by mitogen signaling and amino acid availability.

关键词： communicate premise sugar

A NEW DIRECT DISCONTINUOUS GALERKIN METHOD WITH SYMMETRIC STRUCTURE FOR NONLINEAR DIFFUSION EQUATIONS

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2013年第6期31卷 638-662页

作者： chad Vidden Jue Yan Department of Mathematics Iowa State University Ames IA USA

In this paper we continue the study of discontinuous Galerkin finite element methods for nonlinear diffusion equations following the direct discontinuous Galerkin （DDG） meth- ods for diffusion problems [17] and the direct discontinuous Galerkin （DDG） methods for diffusion with interface corrections [18]. We introduce a numerical flux for the test func- tion, and obtain a new direct discontinuous Galerkin method with symmetric structure. Second order derivative jump terms are included in the numerical flux formula and explicit guidelines for choosing the numerical flux are given. The constructed scheme has a sym- metric property and an optimal L2 （L2） error estimate is obtained. Numerical examples are carried out to demonstrate the optimal （k ＋ 1）th order of accuracy for the method with pk polynomial approximations for both linear and nonlinear problems, under one-dimensional and two-dimensional settings.

关键词： Discontinuous Galerkin Finite Element method Diffusion equation Stability,Convergence.

Effect of Loading Frequency on the High Cycle Fatigue Strength of Flax Fiber Reinforced Polymer Matrix Composites

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Renewable Materials 2022年第5期10卷 1185-1200页

作者： Md Zahirul Islam chad A.Ulven Department of Mechanical Engineering North Dakota State UniversityFargoUSA

Among natural fibers,flax fiber reinforced polymer matrix composites show excellent dynamic/fatigue properties due to its excellent damping *** about fatigue limit and effect of loading frequency on fatigue limit is very crucial to know before being used a member as a structural *** limit of fiber reinforced composite is measured through high cycle fatigue strength(HCFS).The effect of loading frequency on the HCFS of flax fiber reinforced polymer matrix composites was investigated using stabilized specimen surface temperature based thermographic and dissipated energy per cycle-based *** of unidirectional flax fiber reinforced thermoset composites were tested under cyclic loading at different percentages of applied stresses for the loading frequencies of 5,7,10,and 15 Hz in order to determine the stabilized surface temperature of the specimen and dissipated energy per fatigue *** approaches predicted similar fatigue limits(HCFS)which showed a good agreement with experimental results from *** of flax fiber reinforced composites decrease little with increasing loading ***,effect of loading frequency on stabilized specimen temperature and dissipated energy per fatigue cycle was also *** specimen surface temperature increases with loading frequency,dissipated energy per-cycle does not change with loading *** degradation at higher loading frequencies may play a significant role in decreasing HCFS with increasing loading frequency.

关键词： Fiber reinforced material fatigue limit fatigue modelling loading frequency life prediction

Drag reducing nose fairings for existing freight train locomotives

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Aerodynamics 2022年第1期4卷 780-797页

作者： chad L.Stucki Daniel Maynes Corvid Technologies MooresvilleNC28115USA Department of Mechanical Engineering Brigham Young UniversityProvoUT84602USA

At cruising speed,one of the most significant contributing factors to train fuel consumption is aerodynamic drag,and the leading locomotive experiences much more drag than any other car in the *** work reports on the drag reduction that can be realized by the use of add-on nose fairings that are deployed on leading locomotives in a train *** types of fairing shapes were considered and all fairing walls are *** is anticipated that the fairing shapes would result from the deployment of easily stowed panels in an origami inspired *** of the fairing shapes has the appearance of a wedge and the other fairing is also wedge shaped,but with flow directing side wall *** each general fairing shape,the important dimensions were parametrically varied in a systematic manner to identify the dimensions that yield maximum drag *** the first shape,45 different scenarios were considered;for the second shape,15 were considered.A steady commercial computational fluid dynamic solver was employed to solve the flow field and locomotive drag for each of the *** best performing wedge-shaped fairing reduced the leading locomotive drag by nominally 14%and the best performing fairing shape with the side walls reduced the drag by 17%.

关键词： Drag reduction Front-fairing Origami Locomotive

Mediator Complex Dependent Regulation of Cardiac Development and Disease

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Genomics, Proteomics & Bioinformatics 2013年第3期11卷 151-157页

作者： chad E. Grueter Division of Cardiovascular Medicine Department of Internal Medicine University of Iowa Carver College of Medicine

Cardiovascular disease （CVD） is a leading cause of morbidity and mortality. The risk factors for CVD include environmental and genetic components. Human mutations in genes involved in most aspects of cardiovascular function have been identified, many of which are involved in transcriptional regulation. The Mediator complex serves as a pivotal transcriptional reg- ulator that functions to integrate diverse cellular signals by multiple mechanisms including recruit- ing RNA polymerase II, chromatin modifying proteins and non-coding RNAs to promoters in a context dependent manner. This review discusses components of the Mediator complex and the contribution of the Mediator complex to normal and pathological cardiac development and func- tion. Enhanced understanding of the role of this core transcriptional regulatory complex in the heart will help us gain further insights into CVD.

关键词： Mediator complexCardiac disease Transcription Development

Covering Your Bases： Inheritance of DNA Methylation in Plant Genomes

在线全文

学校读者我要写书评

暂无评论

Molecular Plant 2014年第3期7卷 472-480页

作者： chad E. Niederhuth Robert J. Schmitz Department of Genetics University of Georgia Athens GA 30602 USA

Cytosine methylation is an important base modification that is inherited across mitotic and meiotic cell divisions in plant genomes. Heritable methylation variants can contribute to within-species phenotypic variation. Few methylation variants were known until recently, making it possible to begin to address major unanswered questions： the extent of natural methylation variation within plant genomes, its effects on phenotypic variation, its degree of depend- ence on genotype, and how it fits into an evolutionary context. Techniques like whole-genome bisulfite sequencing （WGBS） make it possible to determine cytosine methylation states at single-base resolution across entire genomes and populations. Application of this method to natural and novel experimental populations is revealing answers to these long-standing questions about the role of DNA methylation in plant genomes.

关键词： DNA methylation epigenetics epiallele whole-genome bisulfite sequencing.

Longwall automation:trends,challenges and opportunities

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2017年第5期27卷 733-739页

作者： Jonathon C.Ralston chad O.Hargrave Mark T.Dunn Coal Mining Research Program CSIRO EnergyBrisbaneAustralia

This paper explores the ongoing development and implementation of longwall automation technology to achieve greater levels of underground coal mining performance. The primary driver behind the research and development effort is to increase the safety, productivity and efficiency of longwall mining operations to enhance the underlying mining business. A brief review of major longwall automation challenges is given followed by a review of the insights and benefits associated with the LASC longwall shearer automation solution. Areas of technical challenge in sensing, decision support, autonomy and human interaction are then highlighted, with specific attention given to remote operating centres, proximity detection and systems-level architectures in order to motivate further automation system *** vision for a fully integrated coal mining ecosystem is discussed with the goal of delivering a highperformance, zero-exposure and environmentally coherent mining operations.

关键词： Safety Productivity Environment Mining automation Longwall mining Remote mining Sensing

Recreation ecology research in China’s protected areas:progress and prospect

在线全文

学校读者我要写书评

暂无评论

Ecosystem Health and Sustainability 2020年第1期6卷 511-522,510页

作者： Linsheng Zhong Xiangju Zhang Jinyang Deng chad Pierskalla Institute of Geographic Sciences and Natural Resources Research Chinese Academy of SciencesBeijingChina College of Resources and Environment University of Chinese Academy of SciencesBeijingChina Department of Culture and Tourism Guizhou Normal CollegeGuiyangChina Department:School of Natural Resources West Virginia UniversityMorgantownWVUSA

As a type of tourist destination,Protected Areas(PAs)have been the focus of recreation ecology research since their *** contradiction between recreation and ecological protection of PAs in China is more prominent than in other countries because of China’s large population density and complex PA management ***,a review of related research is urgent for promoting sustainable tourism development of PAs in *** quantitative analysis with a literature review,this study analyzed the historical development process and current research topics of recreation ecology in China’s PAs,focusing on the impacts of tourism on the natural environment,environmental management of tourism,and the development of different types of sustainable tourism in ***,the research gaps are as follows:(1)studies on impact mechanism of tourism based on long-term monitoring are lacking;(2)the existence of numerous local communities in most of the PAs in China is usually ignored;(3)insufficient attention has been paid to the impacts of tourism infrastructure construction;(4)assessments of sustainable PA tourism are ***,this paper presents implications for future research and serves as a reference for PA tourism management in other countries.

关键词： Recreation ecology protected area China sustainable tourism

Simulation study on the emittance compensation of off-axis emitted beam in RF photoinjector

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics C 2016年第11期40卷 184-190页

作者：黄瑞萱 chad Mitchell 贾启卡 Christos Papadopoulos Fernando Sannibale [1NSRL University of Science and Technology of ChinaHefei 230029China ATAP Lawrence Berkeley National LaboratoryOne Cyclotron RoadBerkeleyCalifornia94720USA

To make full use of the photocathode material and improve its quantum efficiency lifetime, it can be necessary to operate the laser away from the cathode center in photoinjectors. In RF guns, the off-axis emitted beam will see a time-dependent RF effect, which would generate a significant growth in transverse emittance. It has been demonstrated that such an emittance growth can be almost completely compensated by orienting the beam on a proper orbit in the downstream RF cavities along the injector [1]. In this paper we analyze in detail the simulation techniques used in reference [1] and the issues associated with them. The optimization of photoinjector systems involving off-axis beams is a challenging problem. To solve this problem, one needs advanced simulation tools including both genetic algorithms and an efficient algorithm for 3D space charge. In this paper, we report on simulation studies where the two codes ASTRA and IMPACT-T are used jointly to overcome these challenges, in order to optimize a system designed to compensate for the emittance growth in a beam emitted off axis.

关键词： photoinjector off-axis emission genetic algorithm ASTRA IMPACT-T RF effect emittance compen-sation