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Time-periodic solutions of the Einstein's field equations Ⅰ:general framework

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Science China mathematics 2010年第5期53卷 176-193页

作者： KONG DeXing1 & LIU KeFeng2 1department of mathematics,Zhejiang university,Hangzhou 310027,China 2department of mathematics,university of california at los angeles,ca 90095,usa

In this paper,we develop a new algorithm to find the exact solutions of the Einstein's field ***-periodic solutions are constructed by using the new *** singularities of the time-periodic solutions are investigated and some new physical phenomena,such as degenerate event horizon and time-periodic event horizon,are *** applications of these solutions in modern cosmology and general relativity are expected.

关键词： Einstein’s field equations time-periodic solution Riemann curvature tensor singularity event horizon

Global existence of smooth solutions to two-dimensional compressible isentropic Euler equations for Chaplygin gases

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Science China mathematics 2010年第3期53卷 719-738页

作者： KONG DeXing 1 , LIU KeFeng 2 & WANG YuZhu 3, 1 department of mathematics, Zhejiang university, Hangzhou 310027, China 2 department of mathematics, university of california at los angeles, ca 90095, usa 3 department of mathematics, Shanghai Jiao Tong university, Shanghai 200248, China department of mathematics Zhejiang University Hangzhou China department of mathematics University of California at Los Angeles Los Angeles USA department of mathematics Shanghai Jiao Tong University Shanghai China

In this paper we investigate the two-dimensional compressible isentropic Euler equations for Chaplygin gases. Under the assumption that the initial data is close to a constant state and the vorticity of the initial velocity vanishes, we prove the global existence of the smooth solution to the cauchy problem for twodimensional flow of Chaplygin gases.

关键词： Chaplygin gases compressible Euler equations irrotational flow null condition cauchy problem smooth solution

Posterior gut development in Drosophila:a model system for identifying genes controlling epithelial morphogenesis

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Cell Research 1998年第4期8卷 273-284页

作者： LENGYEL JUDITH A XUE JUN LIU (department of Molecular, Cell and Developmental Biology university of california at los angeles, los angeles, ca usa, 90095-1606 usa) department of Molecular Cell and Developmental Biology University of California at Los Angeles Los Angeles USA

The posterior gut of the Drosophila embryo, consisting of hindgut and Malpighian tubules, provides a simple,well-defined system where it is possible to use a genetic approach to define components essential for epithelial *** review here the advantages of Drosophila as a model genetic organism, the morphogenesis of the epithelial structures of the posterior gut, and what is known about the genetic requirements to form these *** overview, primordia are patterned by expression of hierarchies of transcription factors; this leads to localized expression of cell signaling molecules, and finally, to the least understood step: modulation of cell adhesion and cell shape. We describe approaches to identify additional genes that are required for morphogenesis of these simple epithelia, particularly those that might play a structural role by affecting cell adhesion and cell shape.

关键词： Organogenesis cell rearrangement convergent extension hindgut Malpighian tubule

FOUR STEP SCHEME FOR GENERAL MARKOVIAN FORWARD-BACKWARD SDES

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Journal of Systems Science & Complexity 2010年第3期23卷 546-571页

作者： Jin MA Jiongmin YONG Yanhong ZHAO department of mathematics University of Southern California Los Angeles CA 90089 USA department of mathematics University of Central Florida Orlando FL 32816 USA department of mathematics Purdue University West Lafayette IN 47907 USA

This paper studies a class of forward-backward stochastic differential equations (FBSDE)in a general Markovian *** forward SDE represents a large class of strong Markov semimartingales,and the backward generator requires only mild regularity *** authors showthat the Four Step Scheme introduced by Ma,et al.(1994) is still effective in this ***,the authors show that the adapted solution of the FBSDE exists and is unique over any prescribedtime duration;and the backward components can be determined explicitly by the forward componentvia the classical solution to a system of parabolic integro-partial differential *** importantconsequence the authors would like to draw from this fact is that,contrary to the general belief,in aMarkovian set-up the martingale representation theorem is no longer the reason for the well-posednessof the FBSDE,but rather a consequence of the existence of the solution of the decoupling integralpartialdifferential ***,the authors briefly discuss the possibility of reducing the regularityrequirements of the coefficients by using a scheme proposed by *** (2002) to the current case.

关键词： Forward-backward stochastic differential equations Four Step Scheme parabolic integropartial differential equation strong Markov semi-martingales.

OPTIMAL COARSE GRID SIZE IN DOMAIN DECOMPOSITION

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Journal of Computational mathematics 1994年第4期12卷 291-297页

作者： Tony Chan Jian-Ping Shao(department of mathematics, university of califoruia, los angeles, usa) university of california 美国

In most domain decomposition (DD) methods, a coarse grid solve is employed to provide the global coupling required to produce an optimal method. The total cost of a method can depend sensitively on the choice of the coaxse grid size H. In this paper, we give a simple analysis of this phenomenon for a model elliptic problem and a variant of Smith's vertex space domain decomposition method [11, 3]. We derive the optimal value Hopt which asymptotically minimises the total cost of method (number of floating point operations in the sequential case and execution time in the parallel case), for subdomain solvers with different complekities. Using the value of Hopt, we derive the overall complexity of the DD method, which can be significantly lower than that of the subdomain solver

关键词： UCLA OPTIMAL COARSE GRID SIZE IN DOMAIN DECOMPOSITION caM

Environmental Occurrence of Selenium in Waters and Related Health Significance

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Biomedical and Environmental Sciences 1997年第2期10卷 292-299页

作者： JANE L. VALENTINE(School of Public Health, university of california at los angeles, los angeles, ca 90024, usa) School of Public Health University of California at Los Angeles 90024 USA.

Appreciable amounts of selenium in spring and well waters can be found due to geological occurrence. Concentrations of as much as 400 9000 μg/l have been reported in U. S. *** levels are 8 to 180 times the current EPA drinking water standard and approximate dietary exposures of 4900μg in selenosis regions of China. Reviews of health significance of the elevated drinking water exposures to U. S. populations revealed elevated concentrations of selenium in urine and blood. A decrease in glutathione peroxidase activity in such instances was noted. However noticeable symptoms and signs seem absent in studies reviewed. A comparison of intake levels (diet or drinking water) to urinary excretion for residents of China and the U. S. produced a correlation coefficient, r = 0. 82 (P < 0. 01 ) for the three research studies available

关键词： In Am Environmental Occurrence of Selenium in Waters and Related Health Significance

An Efficient Algorithm for Mobile Localization in Sensor Networks

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International Journal of Automation and computing 2012年第6期9卷 594-599页

作者： Xin-Min Xu 1 Yao Chen 1 Wen-Yao Xu 2 Fang Gong 2 1 department of Information Science and Electronic Engineering,Zhejiang university,Hangzhou 310027,China 2 Electrical Engineering department,university of california,los angeles 90095,usa department of Information Science and Electronic Engineering Zhejiang University Hangzhou China Electrical Engineering department University of California Los Angeles USA

Node localization is a fundamental problem in wireless sensor *** are many existing algorithms to estimate the locations of the ***,most of the methods did not consider the presence of *** practice,obstacles will lead to blockage and reflection of communication signals between sensor ***,the presence of obstacles will greatly affect the localization *** this paper,we implement an obstacle-handling algorithm based on the localization tool developed by MIT,The experimental result shows that the enhanced algorithm can reduce the average distance error by up to 46 %,compared to the original algorithm.

关键词： Wireless sensor network automatic localization intelligent computing optimization simulation.

Heat flow distribution in Chinese continent and its adjacent areas

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Progress in Natural Science:Materials International 2008年第7期18卷 843-849页

作者： Wei Tao a,*, Zhengkang Shena,b a State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China b department of Earth and Space Sciences, university of california, los angeles, ca 90095-1567, usa State Key Laboratory of Earthquake Dynamics Institute of Geology China Earthquake Administration Beijing 100029 China department of Earth and Space Sciences University of California Los Angeles CA 90095-1567 USA

Using a compilation of 6980 heat flow measurements, we produce a new heat flow map for the Chinese continent and its adjacent areas. We develop an objective and integrated method to interpolate the heat flow data, taking into account both the uniformity within geological units and coherency of regional heat flow. The geologic units are outlined based on Zhang et al.’s active tectonic block model. Our heat flow model is presented in two formats: a contour map and a heat flow dataset with values on a 1×1° grid for the Chinese continent and its adjacent areas, reflecting detailed variations in some regions. Also provided is a resolution map which helps understand the reliability of the heat flow model. Our results reveal that (1) Heat flows in the eastern part of the Chinese continent are relatively higher than those in the western part except that in the Tibetan Plateau area. (2) Heat flows in the Ordos and North China blocks are around 60 mW/m2, and are 50–55 mW/m2 in South China except for the continental marginal sea regions. (3) Heat flow is the lowest in the Junggar Basin, only 35–45 mW/m2, and is 45–55 mW/m2 in the Tarim Basin. The results of this study provide an important data- set for studies on thermal and rheological structures of the Chinese continent and its adjacent areas.

关键词： Heat flow Chinese continent and its adjacent areas Geological units Contour map Resolution map

Analysis of Environmental and Socio-economic Determinants Affecting Population Longevity Level at County Level in China

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Chinese Journal of Population,Resources and Environment 2005年第1期3卷 36-41页

作者： Lu Jiehua , Wang Hongbo 1 2 & Pan Yi 1 1. Institute of Population Research, Peking university, Beijing 100871, China 2. department of Sociology, university of california at los angeles, los angeles, usa. Institute of Population Research Peking University Beijing 100871 China department of Sociology University of California at Los Angeles Los Angeles United States

Based on the current literature, this paper is mainly intended to test whether environmental factors and socio-economic factors will have direct effect on the longevity at county level in China in order to determine the major determinants affecting local longevity level. Using the multi-regression model, we find the result that factors such as temperature, climate, longitude, type of soils, as well as type of agricultural food production play a major role in shaping the longevity at county level, and that socio- economic factors like infant mortality and gross death rate also have some direct impact on longevity, but the degree of impact is not as strong as the above environmental factors.

关键词： longevity socio-economic factors environmental factors