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Two-Dimensional Riemann Problems for the Compressible Euler System

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Chinese Annals of Mathematics,Series B 2009年第6期30卷 845-858页

作者： Yuxi ZHENG Dedicated to Professor Andrew Majda for his 60th Birthday

Riemann problems for the compressible Euler system in two space dimensions are complicated and difficult,but a viable alternative remains *** author lists merits of one-dimensional Riemann problems and compares them with those for the current two-dimensional Riemann problems,to illustrate their ***-dimensional Riemann problems are approached via the methodology promoted by Andy Majda in the spirits of modern applied mathematics;that is,simplified model is built via asymptotic analysis,numerical simulation and theoretical analysis.A simplified model called the pressure gradient system is derived from the full Euler system via an asymptotic ***-of-the-art numerical methods in numerical simulations are used to discern small-scale structures of the solutions,e.g.,semi-hyperbolic *** methods are used to establish the validity of the structure revealed in the numerical *** entire process,used in many of Majda's programs,is shown here for the two-dimensional Riemann problems for the compressible Euler systems of conservation laws.

关键词： Characteristic decomposition Guderley reflection Hodograph transform Pressure gradient system Self-similar Semi-hyperbolic wave Triple point paradox Riemann problem Riemann variable

Ab initio molecular dynamics simulation of the atom packing and density of Al-Ni amorphous alloys

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Science China(Technological Sciences) 2010年第12期53卷 3175-3182页

作者： YU ChunYan1, HUI XiDong1, CHEN XiaoHua1, LIU XingJun1, LIN DeYe1, LIU ZiKui2 & CHEN GuoLiang1 1 State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China 2 Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802, usa State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing China Department of Materials Science and Engineering Pennsylvania State University University Park USA

Al-Ni alloys have better glass forming ability (GFA) than other Al-based alloys. However, the relationship among the atomic arrangement, glass transition, packing density and composition hasn’t been systematically studied. In this paper the ab initio molecular dynamics simulation (AIMD) was performed on the atom packing and density of AlxNi100-x (x=80, 83, 85, 86, 87 and 90) alloys. The pair correlation function and Voronoi tessellation indicated that there are obvious topological and chemical short-range orders in these alloys. The topological structure consists of Al-centered icosahedra like and Ni-centered tri-capped trigonal prism (TTP) like polyhedra. There is strong chemical short-range ordering between Al and Ni atoms indicated by the bond-length of Al-Ni pair shorter than the sum of the radii of Al and Ni atoms, which increases with the increasing of Ni content. It is shown that the densities of amorphous alloys don’t agree with the linear law with a peak at x=85. Based on the features of the structure and density, it is concluded that Al-Ni alloys at x=84–86 have high GFA, which can be extended to multi-component Al-based alloys.

关键词： AIMD Al-Ni alloys density short-range order chemical short-range order

Double-stranded DNA breaks and gene functions in recombination and meiosis

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Cell Research 2006年第5期16卷 402-412页

作者： Wuxing Li~1 Hong Ma~1 ~1The Department of Biology,The Intercollege Graduate Degree Program in Plant Physiology,The Huck Institutes of the Life Sciences,The Pennsylvania State University,University Park,PA 16802,usa The Department of Biology The Intercollege Graduate Degree Program in Plant Physiology The Huck Institutes of the Life Sciences The Pennsylvania State University University Park USA

Meiotic prophase Ⅰ is a long and complex *** recombination is an important process that occursbetween homologous chromosomes during meiotic prophase Ⅰ.Formation of chiasmata,which hold homologous chro-mosomes together until the metaphase Ⅰ to anaphase Ⅰ transition,is critical for proper chromosome *** have suggested that the SPO 11 proteins have conserved functions in a number of organisms in generating sites ofdouble-stranded DNA breaks (DSBs) that are thought to be the starting points of homologous *** these sites of DSBs requires the function of RecA homologs,such as RAD51,DMC 1,and others,as suggested bymutant studies;thus *** to repair these meiotic DSBs results in abnormal chromosomal alternations,leading todisrupted *** discoveries on the functions of these RecA homologs have improved the understanding of themechanisms underlying meiotic homologous recombination.

关键词： meiosis homologous recombination double-stranded DNA breaks SPO11 RAD51 DMC1

The Ray Wu Society for Life Sciences

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Chinese Science Bulletin 2003年第8期48卷 839-840页

作者： MA Hong Department of Biology and The Huck Institute for Life Sciences, The Pennsylvania State University, 315 Wartik Laboratory, University Park, PA 16802, usa (e-mail: Hxm16@psu.edu) Penn State Univ Dept Biol Wartik Lab 315 University Pk PA 16802 USA Penn State Univ Huck Inst Life Sci Wartik Lab 315 University Pk PA 16802 USA

The Ray Wu Society for Life Sciences (RWS) is a non-profit professional society of Chinese-American and Chinese life scientists with the goal to promote scientific communication among the scientists between usa and China and the life science research in China. The members of the RWS, now numbered more than 300, are a group of elite biologists who have reached the level of assistant professor or equivalent in their careers and are experts of their respective fields including molecular biology and genetics, cell and developmental biology, me- dicine, pharmacology, plant biology, and biotechnology. RWS was founded in early 1998 by a group of life scientists who have come from China during the last 22 years. With the encouragement of Dr. Chris Tan, the Director of the Molecular Biology Institute in Singapore, who proposed to set up a fund in the name of Prof. Ray Wu of Cornell University to recognize his contribution to the academic exchange between China and the usa. A quick positive response was reflected from American Chinese scholars with a further proposal of forming a professional society. This initiative spread rapidly and widely throughout the existing networks of Chinese life-science professionals.

关键词：生命科学中国美国学术交流科学研究

How to build a functional gabaergic synapses?

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How to build a functional gabaergic synapses?

System Performance and Thrust Chamber Dynamics of Airbreathing Pulse Detonation Engines

中国神经科学学会第四次会员代表大会暨第七届全国学术会议

作者： Gong CHEN Department of Biology,The Huck Institutes of Life Sciences,The Pennsylvania State University,University Park,PA 16802,usa

GABA is the predominant inhibitory neurotransmitter in the adult *** of GABAergic neurotransmission may be involved in serious neurological disorders,including epilepsy,anxiety,depression,and schizophrenia. Despite the vital function of GABA in the brain,the molecular mechanism of GABAergic synapse formation is still largely *** have employed primary neuronal cultures to study the presynaptic and postsynaptic differentiation during GABAergic *** found that GABAergic postsynaptic assembly is a very rapid process,much faster than its counterpart presynaptic assembly in cultured embryonic *** understand why it is so rapidly assembled,we used heterologous expression system HEK293 cells to study the essential molecular composition of GABAergic postsynaptic *** demonstrate that besides GABAA receptors,which is necessary to detect GABA transmitter,the only molecule needed is a cell adhesion molecule neuroligin-2 to build a fully functional GABAergic postsynaptic apparatus. Furthermore,the delta subunit-containing GABAA receptors,which are usually expressed in extrasynaptic membranes in neurons,are also excluded from the molecularly reconstituted GABAergic synapses formed on HEK293 ***,we have built an efficient system that will allow precise dissection of the molecular mechanisms of GABAergic synapse assembly.

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System Performance and Thrust Chamber Dynamics of Airbreathi...

A Study on Solid/Melt Interfaces and the Formation of<100> Texture in Solidified FCC Metals

第四届海峡两岸计算流体力学学术研讨会

作者： Vigor YANG and Fuhua MA Department of Mechanical Engineering, The Pennsylvania State University University Park, Pennsylvania 16802, usa

＜正＞ This paper deals with the system performance and thrust chamber dynamics of airbreathing pulse detonation engines. The work accommodates all the essential elements of an engine, including inlet, manifold/valve, injector, combustor, and nozzle. Emphasis is placed on multi-tube configurations with repetitive flow-distribution. The primary outcome is a general framework, in a form suitable for routine practical applications, for assessing the effects of all known processes on engine dynamics. It also helps designers and researchers to optimize the overall system performance and to identify the major technological barriers at minimal computational expense. Major variables and phenomena of consideration include fueling strategy, injection scheme, chamber conditions, and configuration geometry.

关键词： pulse detonation engine system performance thrust chamber.

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Journal of Materials Science & Technology 1997年第6期13卷 457-461页

作者： D.Y.Li(Dept. of Mater. Sci & Eng., The Pennsylvania State University, University Park, PA 16802, usa )B.Debray and J.A.Szpunar(Dept. of Metall. Eng., McGill University, 3450 Uuiversity Street, Molitreal, PQ, Canada H3A 2A7) Dept. of Mater. Sci and Eng. Pennsylvania State University University Park PA 16802 United States Dept. of Metall. Eng. McGill University 3450 University Street Montreal PQ H3A 2A7 Canada

The (100) texture of solidified fcc metals, caused by the preferential (100) dendrite growth, could be closeIy related to solid/melt interfaces which behave differently along different crystallographic orientation. The stability and roughness of {111} and {100} solid/melt interfaces of fcc metals were investigated using a modified Temkin multi-layer model. It is demonstrated that {100}crystal/melt interface is more unstable and rougher than {111} interface. The effect of the stability of crystal/melt interface on the (100) texture formation in solidified fcc metals has been analysed and discussed.

关键词： FCC A Study on Solid/Melt Interfaces and the Formation of<100 Texture in Solidified FCC Metals

Plant fertility defects induced by the enhanced expression of microRNA167

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Cell Research 2006年第5期16卷 457-465页

作者： Peng Ru~1 Lin Xu~1 Hong Ma~(2,3) Hai Huang~(1,2) ~1National Laboratory of Plant Molecular Genetics,Shanghai Institute of Plant Physiology and Ecology,Shanghai Institute for Biological Sciences,300 Fenglin Road,Shanghai 200032,China ~2SIBS-SJTU-PSU Joint Center for Life Sciences,Shanghai Institute of Plant Physiology and Ecologgy,Shanghai Institute for Biological Sciences,300 Fenglin Road,Shanghai 200032,China ~3Department of Biology and the Huck Institute for the Life Sciences,The Pennsylvania State University,University Park,PA 16802,usa National Laboratory of Plant Molecular Genetics Shanghai Institute of Plant Physiology and Ecology Shanghai Institute for Biological Sciences Shanghai China SIBS-SJTU-PSU Joint Center for Life Sciences Shanghai Institute of Plant Physiology and Ecology Shanghai Institute for Biological Sciences Shanghai China Department of Biology and the Huck Institute for the Life Sciences The Pennsylvania State University University Park USA

The plant hormone auxin plays a critical role in regulating plant growth and *** advances havebeen made in the understanding of auxin response pathways,primarily by the characterization of auxin response mu-tants in *** addition,microRNAs (miRNAs) have been shown to be critical regulators of genes importantfor normal plant development and ***,little is known about possible interactions between miRNAsand hormonal signaling during norlnal *** we show that an Arabidopsis microRNA,miR167,whichhas a complementary sequence to a portion of the A UXIN RESPONSE FACTOR6 (ARF6) and ARF8 mRNAs,can causetranscript degradation for ARFS,but not for *** report phenotypic characterizations of35S::MIR167b transgeniclines,and show that severe 35S::MIR167b transgenic lines had phenotypes similar to those of an arf6 arf8 double *** transgenic phenotypes suggest that miR167 may repress ARF6 at the level of *** demonstrate that thetransgenic plants are defective in all four whorls of floral *** the transgenic flowers,filaments were abnormallyshort,anthers could not properly release pollen,and pollen grains did not *** results provide an importantlink between the miRNA-mediated regulatory pathway of gene expression and the auxin signaling network promotingplant reproductive development.

关键词： Arabidopsis auxin response factor microRNA167 floral organ pollen germination

Proteomic identification of potential target proteins regulated by an ASK1-mediated proteolysis pathway

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Cell Research 2006年第5期16卷 489-498页

作者： Kaiming Cao State Key Laboratory of Genetic Engineering Department of Biochemistry and Molecular Biology School of Life Sciences Fudan University Shanghai 200433 China

The ASK1 (ARABIDOPSIS SKP1-LIKE) protein is a critical component of the SCF (Skpl-Cullin-F box protein)ubiquitin ligase complexes that recruit target proteins for degradation by the 26S *** investigate proteinsthat are affected by the ASK1-mediated proteolysis pathway in Arabidopsis flowers,we compared the proteomes of theArabidopsis wild type and ask1 mutant flower buds using two-dimensional electrophoresis (2-DE).Ten protein spots withhigher or lower abundance in the ask1 mutant flowers compared to wild type flowers were excised and subjected to furthermass spectrometry (MS) *** results showed that they were proteins involved in photomorphogenesis,circadianoscillation,post-translation process,stress-responses and cell expansion or elongation,suggesting that those processeswere affected in the ask1 *** transcript levels of these genes were also compared based on the Affymetrix genechip microarray *** significant difference was observed for most of the genes,suggesting that the proteins withelevated levels of accumulation in the ask1 mutant could be candidate targets regulated by an ASKl-mediated *** results help to elucidate the pleiotropic functions of ASK1 in Arabidopsis developmental processes andalso demonstrate the importance and necessity of studying protein levels with respect to gene functions.

关键词： ASK1 two-dimensional polyacrylamide gel electrophoresis mass spectrometry proteolysis