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Characteristics of fMRI BOLD signal and its neurophysiological mechanism

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Progress in Natural science:Materials International 2007年第6期17卷 630-638页

作者： Zhao Xiaohu1,2, Wu Yigen3 and Guo Shengli3(1. college of Life sciences, Zhejiang university, Hangzhou 310058, china 2. Imaging Department of Tongji Hospital of Tongji university, Shanghai 200065, china 3. college of mathematics and physics, nanjing university of information science and technology, nanjing 2.0044, china) college of Life sciences Zhejiang University Hangzhou 310058 China Imaging Department Tongji Hospital Tongji University Shanghai 200065 China college of mathematics and physics Nanjing University of Information Science and Technology Nanjing 210044 China

The functional magnetic resonance imaging (fMRI) based on blood oxygen level dependent (BOLD) contrast has emerged as one of the most potent noninvasive tools for mapping brain function and has been widely used to explore physiological, pathological changes and mental activity in the brain. Exploring the nature and property of BOLD signal has recently attracted more attentions. Despite that great progress has been made in investigation of the characteristics and neurophysiological basis, the exact nature of BOLD signal remains unclear. In this paper we discuss the characteristics of BOLD signals, the nonlinear BOLD response to external stimuli and the relation between BOLD signals and neural electrophysiological recordings. Furthermore, we develop our new opinions regarding nonlinear BOLD response and make some perspectives on future study.

关键词： functional magnetic resonance imaging blood oxygen level dependent nonlinear response neural electrophysiological activity.

Travelling wave solutions of a generalized Camassa-Holm-Degasperis-Procesi equation

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science china mathematics 2011年第3期54卷 555-572页

作者： DENG ShengFu1, GUO BoLing2 & WANG TingChun2,3 1Department of mathematics, Zhanjiang Normal university, Zhanjiang 524048, china 2Institute of Applied physics and Computational mathematics, Beijing 100088, china 3 college of math and physics, nanjing university of information science and technology, nanjing 2.0044, china Department of mathematics Zhanjiang Normal University Zhanjiang China Institute of Applied physics and Computational mathematics Beijing China college of math and physics Nanjing University of Information Science and Technology Nanjing China

The travelling wave solutions of a generalized Camassa-Holm-Degasperis-Procesi equation ut-uxxt + (1 + b)umux = buxuxx + uuxxx are considered where b > 1 and m are positive integers. The qualitative analysis methods of planar autonomous systems yield its phase portraits. Its soliton wave solutions, kink or antikink wave solutions, peakon wave solutions, compacton wave solutions, periodic wave solutions and periodic cusp wave solutions are obtained. Some numerical simulations of these solutions are also given.

关键词： homoclinic orbits heteroclinic orbits peakon wave solutions compacton wave solutions periodic cusp wave solutions

Mechanical behaviors of alumina ceramics doped with rare-earth oxides

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Rare Metals 2010年第5期29卷 456-459页

作者： YAO Yijun LI Chuncheng WANG Ling JIANG Xiaolong QIU Tai School of mathematics and physics Nanjing University of Information Science & Technology Nanjing 210044 China college of Materials science and Engineering Nanjing University of Technology Nanjing 210009 China

The effects of three types of additives Y2O3, La2O3, and Sm2O3 on the sintering and mechanical behaviors of alumina ceramics were investigated. The bending strengths of alumina ceramics with Sm2O3 and Y2O3 additions were 455 and 439 MPa, respectively, higher than that with La2O3 addition. The fi＇acture toughness of the ceramics with Sm2O3 and Y2O3 were also higher than that with La2O3 addition. The fracture mode of rare earth oxides doped alumina ceramics exhibited obvious transgranular fractures as well as intergranular fracture. The results of research show that the improvement of bending strength and fracture toughness of alumina ceramics with rare earth oxides was achieved by refining the grain size and strengthening the grain boundary.

关键词： rare earths alumina doping mechanical properties microstructure

Investigation of fine and complex vortex circulation structures

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science china Earth sciences 2010年第10期53卷 1552-1558页

作者： LUO ZheXian1,MA GeLan1 & PING Fan2 1 Remote Sensing college,nanjing university of information science and technology,nanjing 2.0044,china 2 Laboratory of Cloud-Precipitation physics and Severe Storms(LACS),Institute of Atmospheric physics,Chinese Academy of sciences,Beijing 100029,china Remote Sensing college Nanjing University of Information Science and Technology Nanjing China Laboratory of Cloud-Precipitation physics and Severe Storms (LACS) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China

The formation and evolution of fine and complicated vortex circulation structures were investigated using a two-dimensional quasi-geostrophic barotropic model *** find that the highly localized asymmetric and complex configuration of energy transfer flux between large-and small-scale components is caused by the nonlinear interaction between a large-scale vortex with an initial axi-symmetric flow and four beta meso-scale *** complex structure is characterized by a fine pattern,which contains seven closed systems with spatial scales of less than 100 km,embedded in a positive flux wave train and a negative wave train,*** average wind speed decreased with time in the positive flux region,but was nearly unchanged in the negative flux *** pattern reveals the evolutionary asymmetry and localization of wind speed of the major *** track of the major vortex center has a trend toward the center of the negative flux center,indicating that there is a certain relation between the complex structure of the energy transfer flux and the motion of the major vortex *** results imply that the formation and evolution of the fine and complex structure should be attributed to the nonlinear interaction between the vortices at different spatial scales.

关键词： vortex complex structure non-linear interaction energy cascade

Complex transient dynamics of hidden attractors in a simple 4D system

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Chinese physics B 2015年第5期24卷 270-274页

作者：党小宇李春彪包伯成武花干 college of Electronic and information Engineering Nanjing University of Aeronautics and Astronautics School of Electronic & information Engineering Nanjing University of Information Science & Technology School of information science and Engineering Changzhou University School of Electronic and Optical Engineering Nanjing University of Science and Technology

A simple four-dimensional system with only one control parameter is proposed in this paper. The novel system has a line or no equilibrium for the global control parameter and exhibits complex transient transition behaviors of hyperchaotic attractors, periodic orbits, and unstable sinks. Especially, for the nonzero-valued control parameter, there exists no equilibrium in the proposed system, leading to the formation of various hidden attractors with complex transient dynamics. The research results indicate that the dynamics of the system shows weak chaotic robustness and depends greatly on the initial states.

关键词： transient dynamics hidden attractor equilibrium

ANALYTICAL SOLUTION OF NONLINEAR BAROTROPIC VORTICITY EQUATION

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Journal of Hydrodynamics 2008年第4期20卷 530-535页

作者： WANG Yue-peng SHI Wei-hl college of mathematics and physics Nanjing University of Information Science and Technology Nangjing210044 China Jiangsu Key Laboratory of Meteorological Disaster Nangjing University of Information Science and Technology Nangjing 210044 China Department of mathematics Shanghai University Shanghai 200072 China

The C^k （k ≥ 3） stability of nonlinear barotropic vorticity equation was proved. The necessary and sufficient conditions for the initial value problem to be well-posed were presented. Under the conditions of well-p... 详细信息

关键词： nonlinear barotropic vorticity equation stability well-posedness analytical solution

Regularity criterion to some liquid crystal models and the Landau-Lifshitz equations in R^3

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science china mathematics 2008年第10期51卷 1787-1797页

作者： FAN JiShan1 & GUO BoLing2 1 college of information science and technology, nanjing Forestry university, nanjing 210037, china 2 Institute of Applied physics and Computational mathematics, P. O. Box 8009, Beijing 100088, china college of information science and technology Nanjing Forestry University Nanjing China Institute of Applied physics and Computational mathematics Beijing China

We consider the regularity problem under the critical condition to some liquid crystal models and the Landau-Lifshitz equations. The Serrin type reularity criteria are obtained in the terms of the Besov spaces.

关键词： liquid crystal Landau-Lifshitz equations critical condition Besov space

A computational investigation of boron-doped chromium and chromium clusters by density functional theory

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science china(physics,Mechanics & Astronomy) 2010年第5期53卷 812-817页

作者： GE GuiXian1,JING Qun1 & LUO YouHua2,3 1 Key Laboratory of Ecophysics and Department of physics,Normal college,Shihezi university,Xinjiang 832003,china 2 School of science,East china university of science and technology,Shanghai 200237,china 3 Institute of Theoretical physics,School of physics and information Optoelectronics,Henan university,Kaifeng 475004,china Key Laboratory of Ecophysics and Department of physics Normal College Shihezi University Xinjiang China School of science East China University of Science and Technology Shanghai China Institute of Theoretical physics School of Physics and Information Optoelectronics Henan University Kaifeng China

The geometries,stabilities and electronic properties of Crn and CrnB(n=2-9) clusters have been systematically investigated by density functional *** results suggest that the lowest energy structures for CrnB clusters can be obtained by substituting one Cr atom in Crn+1 clusters with B *** geometries of CrnB clusters are similar to that of Crn+1 clusters except for local structural *** second-order difference and fragmentation energy show Cr4,Cr6,Cr8,Cr3B,Cr5B and Cr8B cluster are the most stable among these studied *** impurity B increases the stabilities of chromium *** B is doped on the Crn clusters,cluster geometry does dominate positive role in enhancing their *** doped B atom does not change the coupling way of the Cr site in Crn clusters,but breaks the symmetry and the Cr atoms are no longer *** doped B atom increases the total magnetic moments of Crn in most cases.

关键词： Crn and CrnB clusters geometries electronic properties

Molecular dynamics simulations on the structures and properties of ε-CL-20-based PBXs ——Primary theoretical studies on HEDM formulation design

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science china Chemistry 2007年第6期50卷 737-745页

作者： XU XiaoJuan1,2, XIAO JiJun1, HUANG Hui3, LI JinShan3 & XIAO HeMing1 1 Department of Chemistry, nanjing university of science and technology, nanjing 210094, china 2 Department of Chemistry, Yancheng Teacher’s college, Yancheng 224002, china 3 Institute of Chemical Materials, china Academy of Engineering physics, Mianyang 621900, china Department of Chemistry Nanjing University of Science and Technology Nanjing China Department of Chemistry Yancheng Teacher’s College Yancheng China Institute of Chemical Materials China Academy of Engineering Physics Mianyang China

Five polymer bonded explosives(PBXs)with the base explosive epsilon-CL-20(hexanitrohexaazaisowurtzi-tane),the most important high energy density compound(HEDC),and five polymer binders(Estane 5703,GAP,HTPB,PEG,and F_(2314))were *** dynamics(MD)method was employed to investigate their binding energies(E_(bind))information and rules were reported for choosing better binders and guiding formulation design of high energy density material(HEDM).According to the calculated binding energies,the ordering of compatibility and stability of the five PBXs was predicted as epsilon-CL-20/PEG 3 ≈ epsilon-CL-20/GAP 314).By pair correlation function g(r)analyses,hydrogen bonds and vdw are found to be the main interactions between the two *** elasticity and isotropy of PBXs based epsilon-CL-20 can be obviously improved more than pure epsilon-CL-20 *** is not by changing the molecular structures of epsilon-CL-20 for each binder to affect the *** safety and energetic properties of these PBXs are mainly influenced by the thermal capability(C_p^(deg))and density(p)of binders,respectively.

关键词： high energy density material (HEDM), hexanitrohexaazaisowurtzitane (CL-20), polymer bonded explosives (PBXs), molecular dynamics (MD), compatibility, safety properties, mechanical properties, energetic properties