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A PCA-based method for ancestral informative markers selection in structured populations

science china(Life sciences) 2009年第10期52卷 972-976页

作者： ZHANG Feng1,3, ZHANG Lei1,3 & DENG Hong-Wen1,2,3 1 Key Laboratory of Biomedical Information Engineering of Ministry of Education, institute of Molecular Genetics, school of Life science and Technology, Xi’an jiaotong university, Xi’an 710049, china 2 institute of bioscience and biotechnology, school of science, beijing jiaotong university, beijing 100044, china 3 Departments of Orthopedic Surgery and Basic Medical science, school of Medicine, university of Missouri-Kansas City, Kansas City, MO 64108, USA 1. Key Laboratory of Biomedical Information Engineering of Ministry of Education Institute of Molecular Genetics School of Life Science and Technology Xi’an Jiaotong University Xi’an 710049 China 3. Departments of Orthopedic Surgery and Basic Medical science School of Medicine University of Missouri-Kansas City Kansas City MO 64108 USA 2. institute of bioscience and biotechnology School of Science Beijing Jiaotong University Beijing 100044 China

Identification of population structure can help trace population histories and identify disease genes. Structured association (SA) is a commonly used approach for population structure identification and association mapping. A major issue with SA is that its performance greatly depends on the informa-tiveness and the numbers of ancestral informative markers (AIMs). Present major AIM selection meth-ods mostly require prior individual ancestry information, which is usually not available or uncertain in practice. To address this potential weakness, we herein develop a novel approach for AIM selection based on principle component analysis (PCA), which does not require prior ancestry information of study subjects. Our simulation and real genetic data analysis results suggest that, with equivalent AIMs, PCA-based selected AIMs can significantly increase the accuracy of inferred individual ancestries compared with traditionally randomly selected AIMs. Our method can easily be applied to whole genome data to select a set of highly informative AIMs in population structure, which can then be used to identify potential population structure and correct possible statistical biases caused by population stratification.

关键词： population structure principle component analysis ancestral informative markers

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Techniques for searching first integrals by Lie group and application to gyroscope system

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science china Mathematics 2005年第8期48卷 1135-1143页

作者： HU Yanxia & GUAn Keying Department of Mathematics, school of science, beijing jiaotong university, beijing 100044, china 1. Department of Mathematics School of Science Beijing Jiaotong University 100044 Beijing China

In the paper, the methods of finding first integrals of an autonomous system using one-parameter Lie groups are discussed. A class of nontrivial one-parameter Lie groups admitted by the classical gyroscope system is found, and based on the properties of first integral determined by the one-parameter Lie group, the fourth first integral of the gyroscope system in Euler case, Lagrange case and Kovalevskaya case can be obtained in a uniform idea. An error on the fourth first integral in general Kovalevskaya case (A=B=2C,zG=0), which appeared in literature is found and corrected.

关键词： one-parameter Lie group first integral gyroscope system

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An efficient algorithm for solving supply chain network equilibria and equivalent supernetwork based traffic network equilibria

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science china(Technological sciences) 2010年第12期53卷 3264-3274页

作者： XU Meng1 & GAO ZiYou2 1 MOE Key Laboratory for Urban Transportation Complex Systems Theory and Technology, beijing jiaotong university, beijing 100044, china 2 institute of Systems science, school of Traffic and Transportation, beijing jiaotong university, beijing 100044, china 1. MOE Key Laboratory for Urban Transportation Complex Systems Theory and Technology Beijing Jiaotong University Beijing 100044 China2. Institute of Systems Science School of Traffic and Transportation Beijing Jiaotong University Beijing 100044 China

This paper is concerned with the algorithm of the supply chain network equilibrium model and its equivalent supernetwork based traffic network equilibrium model with elastic demands. Both models are further written as nonlinear complementarity problems. Semismooth least squares reformulations of the complementarity problems are presented and their convergence properties are investigated. Considering the drawbacks of Quasi-Newton method (using the Fischer-Burmeister function), a semi-smooth Levenberg-Marquardt-type method is proposed to solve the problems. Numerical examples show that the Levenberg-Marquardt-type method can solve the supply chain network equilibrium model and its equivalent supernetwork based traffic network equilibrium model significantly, and is more efficient than the Quasi Newton method and the modified projection method. Furthermore, the Levenberg-Marquardt-type method with the equivalent supernetwork based complementarity formulation can be implemented faster than with the supply chain network equilibrium complementarity formulation.

关键词： supply chain networks traffic network equilibrium supernetwork nonlinear complementarity problem Levenberg Marquardt-type method

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Stem cells and neurodegenerative diseases

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science china(Life sciences) 2008年第4期51卷 287-294页

作者： HOU LingLing & HONG Tao institute of Biological science and Technology, beijing jiaotong university, beijing 100044, china 1. institute of Biological science and Technology Beijing Jiaotong University Beijing 100044 China

Neurodegenerative diseases are characterized by the neurodegenerative changes or apoptosis of neurons involved in networks, which are important to specific physiological functions. With the de-velopment of old-aging society, the incidence of neurodegenerative diseases is on the increase. How-ever, it is difficult to diagnose for most of neurodegenerative diseases. At present, there are too few effective therapies. Advances in stem cell biology have raised the hope and possibility for the therapy of neurodegenerative diseases. Recently, stem cells have been widely attempted to treat neurodegen-erative diseases of animal model. Here we review the progress and prospects of various stem cells, including embryonic stem cells, mesenchymal stem cell and neural stem cells and so on, for the treatments of neurodegenerative diseases, such as Parkinson’s disease, Alzheimer’s disease, Hunt-ington’s disease and Amyotrophic lateral sclerosis/Lou Gehrig’s disease.

关键词： stem cells neurodegenerative diseases therapy

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A new seismic isolation system and its feasibility study

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Earthquake Engineering and Engineering Vibration 2010年第1期9卷 75-82页

作者： Jia Gaofeng~+ and Shi Zhifei~(++) school of Civil Engineering,beijing jiaotong university,beijing 100044,china Graduated Student ++ Professor school of Civil Engineering Beijing Jiaotong University Beijing 100044 China

This paper introduces a new seismic isolation system called a periodic foundation （PF）, where inclusions are periodically arranged. The PF is different from traditional base isolation in that it causes a fundamental frequency shift in the structure, thus reducing its response and generating a frequency gap. If the frequency contents of a seismic wave fall into the gap, it can not propagate in the foundation. Thus, it will exert no influence on the structure above. A systematic study of the band of frequency gap for a 2D PF is conducted. The influence of physical and geometrical parameters such as density and elastic modulus as well as filling fraction of the PF and its materials on the band of frequency gap are investigated, and a design with a frequency gap as low as 2.49-3.72 Hz is achieved. This band of frequency gap corresponds well to the design spectra in earthquake engineering. Numerical simulations of a six-story frame structure with different foundations demonstrate that a proposed PF can greatly reduce the seismic response of an isolated structure. This investigation shows that PFs have great potential in future applications of seismic isolation technology.

关键词： seismic isolation periodic foundation band of frequency gap

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A BATCH ARRIVAL RETRIAL QUEUE WITH STARTING FAILURES,FEEDBACK AND ADMISSION CONTROL

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Journal of Systems science and Systems Engineering 2010年第3期19卷 306-320页

作者： Jinting WANG Peng-Feng ZHOU Department of Mathematics,school of science,beijing jiaotong university,beijing,china Department of Mathematics School of Science Beijing Jiaotong University Beijing China

This paper is concerned with the analysis of a feedback M^[X]/G/1 retrial queue with starting failures and general retrial times. In a batch, each individual customer is subject to a control admission policy upon arrival. If the server is idle, one of the customers admitted to the system may start its service and the rest joins the retrial group, whereas all the admitted customers go to the retrial group when the server is unavailable upon arrival. An arriving customer （primary or retrial） must turn-on the server, which takes negligible time. If the server is started successfully （with a certain probability）, the customer gets service immediately. Otherwise, the repair for the server commences immediately and the customer must leave for the orbit and make a retrial at a later time. It is assumed that the customers who find the server unavailable are queued in the orbit in accordance with an FCFS discipline and only the customer at the head of the queue is allowed for access to the server. The Markov chain underlying the considered queueing system is studied and the necessary and sufficient condition for the system to be stable is presented. Explicit formulae for the stationary distribution and some performance measures of the system in steady-state are obtained. Finally, some numerical examples are presented to illustrate the influence of the parameters on several performance characteristics.

关键词： Batch arrival feedback repair retrial queue starting failure

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A new class of impulse stochastic control models with non-negative control quantity

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science china(Information sciences) 2011年第3期54卷 638-652页

作者： LIU XiaoPeng & LIU KunHui College of science, beijing jiaotong university, beijing 100044, china 1. College of science Beijing Jiaotong University Beijing 100044 China

This paper advances and studies a new class of impulse stochastic control models. Its state structure is defined by a linear stochastic differential equation of the semi-martingale, its control cost function is a twovariable function of pre-control state quantity and control quantity, and its control quantity is kept non-negative. First this paper constructs a new type of variational equations and proves its solution exists. Using a series of stochastic analysis methods to research the solution function of this type of variational equations, this paper proves the existence of optimal control and analyzes its structure in depth. Because of the big difference between the model in this paper and stochastic control models in previous papers, the analysis method here is quite different from previous ones. It is expected that this paper will have important theoretical significance for stochastic control research, along with wide applicative value in finance control and security management.

关键词： impulse stochastic control control quantity variational equation optimal control semi-martingale

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Reliability analysis of M/G/1 queues with general retrial times and server breakdowns

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Progress in Natural science:Materials International 2006年第5期16卷 464-473页

作者： WANG Jinting (Department of Mathematics, beijing jiaotong university, beijing 100044, china) Department of Mathematics Beijing Jiaotong University Beijing 100044 China

This paper concerns the reliability issues as well as queueing analysis of M/G/1 retrial queues with general retrial times and server subject to breakdowns and repairs. We assume that the server is unreliable and customers who find the server busy or down are queued in the retrial orbit in accordance with a first-come-first-served discipline. Only the customer at the head of the orbit queue is allowed for access to the server. The necessary and sufficient condition for the system to be stable is given. Using a supplementary variable method, we obtain the Laplace-Stieltjes transform of the reliability function of the server and a steady state solution for both queueing and reliability measures of interest. Some main reliability indexes, such as the availability, failure frequency, and the reliability function of the server, are obtained.

关键词： retrial queues general retrial times reliability server breakdowns and repairs.

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A new method for counting trees with vertex partition

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science china Mathematics 2008年第11期51卷 2000-2004页

作者： LIU YanPei institute of Mathematics, beijing jiaotong university, beijing 100044, china institute of Mathematics Beijing Jiaotong University Beijing 100044 China

A direct and elementary method is provided in this paper for counting trees with vertex partition instead of recursion, generating function, functional equation, Lagrange inversion, and matrix methods used before.

关键词： tree planted tree joint tree model vertex partition code 05C30 05C10

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Determination of the packing number D_λ(3,W_4^((3)),v)

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science china Mathematics 2009年第11期52卷 2537-2548页

作者： WU Yan & CHANG YanXun institute of Mathematics,beijing jiaotong university,beijing 100044,china 1. institute of Mathematics Beijing Jiaotong University Beijing 100044 China

A t-hyperwheel(t≥3) of length l(or W l(t) for brevity) is a t-uniform hypergraph(V,E) ,where E = {e1,e2,. . .,el} and v1,v2,. . .,vl are distinct vertices of V = il=1 ei such that for i = 1,. . .,l,vi,vi+1 ∈ ei and ei ∩ ej = P,j ∈/{i-1,i,i + 1},where the operation on the subscripts is modulo l and P is a vertex of V which is different from vi,1 i l. In this paper,we investigate the maximum packing problem of MPλ(3,W 4( 3) ,v) . Finally,the packing number Dλ(3,W 4( 3) ,v) is determined for any positive integers v 5 and λ.

关键词： t-(v Γ λ) packing leave packing number group divisible(Γ t) -design candelabra(Γ t) -system

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