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Robustness and breakup of the spiral wave in a two-dimensional lattice network of neurons

Science China(physics,Mechanics & Astronomy) 2010年第4期53卷 672-679页

作者： MA Jun 1,2. TANG Jun 2., ZHANG AiHua 3 & JIA Ya 2.1 department of physics, Lanzhou {2. of Technology, Lanzhou 730050, China 2.department of physics, Central China Normal {2., Wuhan 430079, China 3 College of Electrical and Information Engineering, Lanzhou {2. of Technology, Lanzhou 730050, China 1. department of physics Lanzhou University of Technology Lanzhou 730050 China2. Department of Physics Central China Normal University Wuhan 430079 China3. College of Electrical and Information Engineering Lanzhou University of Technology Lanzhou 730050 China

The robustness and breakup of spiral wave in a two-dimensional lattice networks of neurons are investigated. The effect of small- world type connection is often simplified with local regular connection and the long-range connection with certain probability. The network effect on the development of spiral wave can be better described by local regular connection and changeable long-range connection probability than fixed long-range connection probability because the long-range probability could be changeable in realistic biological system. The effect from the changeable probability for long-range connection is simplified by multiplicative noise. At first, a stable rotating spiral wave is developed by using appropriate initial values, parameters and no-flux boundary conditions, and then the effect of networks is investigated. Extensive numerical studies show that spiral wave keeps its alive and robust when the intensity of multiplicative noise is below a certain threshold, otherwise, the breakup of spiral wave occurs. A statistical factor of synchronization in two-dimensional array is defined to study the phase transition of spiral wave by checking the membrane potentials of all neurons corresponding to the critical parameters(the intensity of noise or forcing current)in the curve for factor of synchronization. The Hindmarsh-Rose model is investigated, the Hodgkin-Huxley neuron model in the presence of the channel noise is also studied to check the model independence of our conclusions. And it is found that breakup of spiral wave is easier to be induced by the multiplicative noise in presence of channel noise.

关键词： spiral wave factor of synchronization breakup multiplicative noise robustness

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Network of tRNA Gene Sequences

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Journal of Shanghai Jiaotong university(Science) 2008年第5期13卷 611-616页

作者：韦芳萍李晟马红孺 department of physics Guangxi University Nanning Institute of Theoretical physics Shanghai Jiaotong University

A network of 3719 tRNA gene sequences was constructed using simplest alignment. Its topology, degree distribution and clustering coefficient were studied. The behaviors of the network shift from fluctuated distribution to scale-free distribution when the similarity degree of the tRNA gene sequences increases. The tRNA gene sequences with the same anticodon identity are more self-organized than those with different anticodon identities and form local clusters in the network. Some vertices of the local cluster have a high connection with other local clusters, and the probable reason was given. Moreover, a network constructed by the same number of random tRNA sequences was used to make comparisons. The relationships between the properties of the tRNA similarity network and the characters of tRNA evolutionary history were discussed.

关键词： similarity network transfer ribonucleic acid gene degree distribution clustering coefficient

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Imaging theory of nonlinear second harmonic and third harmonic generations in confocal microscopy

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Science China(physics,Mechanics & Astronomy) 2004年第1期47卷 8-16页

作者： TANG Zhilie1, XING Da2.& LIU Songhao2.1. department of physics, South China Normal {2., Guangzhou 510631, China 2. School for Information and Optoelectronic Science and Engineering, South China Normal {2., Guangzhou 510631, China Correspondence should be addressed to Tang Zhilie (email: tangzhl@***) Received April 2., 2.03 1. department of physics South China Normal University 510631 Guangzhou China 2. School for Information and Optoelectronic Science and Engineering South China Normal University 510631 Guangzhou China

The imaging theory of nonlinear second harmonic generation (SHG) and third harmonic generation (THG) in confocal microscopy is presented in this paper. The nonlinear effect of SHG and THG on the imaging properties of confocal microscopy has been analyzed in detail by the imaging theory. It is proved that the imaging process of SHG and THG in confocal microscopy, which is different from conventional coherent imaging or incoherent imaging, can be divided into two different processes of coherent imaging. The three-dimensional point spread functions (3D-PSF) of SHG and THG confocal microscopy are derived based on the nonlinear principles of SHG and THG. The imaging properties of SHG and THG confocal microscopy are discussed in detail according to its 3D-PSF. It is shown that the resolution of SHG and THG confocal microscopy is higher than that of single- and two-photon confocal microscopy.

关键词： second harmonic generation, third harmonic generation, confocal microscopy, three-dimensional point spread function.

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Maximal possible accretion rates for slim disks

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Science China(physics,Mechanics & Astronomy) 2009年第12期52卷 2054-2058页

作者： LIN YiQing1 & JIAO ChengLiang2.1 department of Mathematics and physics,Xiamen {2. of Technology,Xiamen 36102.,China 2.department of physics and Institute of Theoretical physics and Astrophysics,Xiamen {2.,Xiamen 361005,China 1. department of Mathematics and physics Xiamen University of Technology Xiamen 361024 China 2. department of physics and Institute of Theoretical physics and Astrophysics Xiamen University Xiamen 361005 China

It was proved in the previous work that there must be a maximal possible accretion rate $ \dot M_{max} $ for a slim disk. Here we discuss how the value of $ \dot M_{max} $ depends on the two fundamental parameters of the disk, namely the mass of the central black hole M and the viscosity parameter α. It is shown that $ \dot M_{max} $ increases with decreasing α, but is almost independent of M if $ \dot M_{max} $ is measured by the Eddington accretion rate $ \dot M_{Edd} $ , which is in turn proportional to M.

关键词： accretion disks black hole physics hydrodynamics

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Fabrication of Dense Ultrafine TiAl Alloys by Spark Plasma Synthesis from Mechanically Activiated Powders

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Journal of Wuhan university of Technology(Materials Science) 2007年第3期22卷 408-411页

作者：夏力 department of Materials Engineering Wuhan University

Powder of Ti-46at%Al alloy was synthesized through mechanical activation（MA） and then sintered and concurrently consolidated in a short sintering time of 900 s by using a spark plasma sintering（SPS） process. The XRD and SEM profiles show that the microstructures of TiAl alloys contained γ TiAl and small amount α-2.Ti3Al phase, whose amount can be controlled by the sintering temperature. The compacts retained the original fine-grained fully densified bodies by avoiding an excessively high sintering temperature. The alloys sintered at higher temperature with this process showed a coarser microstructure. So it is possible to produce dense nanostructured TiAl alloys by mechanically activated spark plasma sintering （MASPS） within a very short period of time.

关键词： titanium aluminides mechanical activation spark plasma sintering (SPS)

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Analysis on cohesive crack opening displacement considering the strain softening effect

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Science China(physics,Mechanics & Astronomy) 2006年第1期49卷 88-101页

作者： WANG Limin1, XU Shilang2.& ZHAO Xiqiang3 1. Mechanics department, Shandong university of Technology, Zibo 2.5049, China 2. Civil Engineering department, Dalian university of Technology, Dalian 11602., China 3. Mathematics department, Ocean university of China, Qingdao 2.6071, China Mechanics department Shandong University of Technology Zibo 255049 China Civil Engineering department Dalian University of Technology Dalian 116024 China Mathematics department Ocean University of China Qingdao 266071 China

In order to investigate the crack propagation in quasi-brittle materials like rock, ceramic and concrete, Hillerborg and his co-researchers abstracted the fracture process zone in front of a stress free crack in terms of a “fictitious crack zone”. On the fictitious crack zone, cohesive stresses distribute following a given softening relationship of stress vs. crack opening. Based on the polynomial or power series expression of cohesive crack opening displacement, the relationship of the cohesive stress vs. the crack opening displacement is established using elastic theory and integral equation, and some unknown physics variables are obtained using variation approach. The calculation results gained in this paper are close to the experimentally test ones.

关键词： cohesive crack, softening, dissipation work, variation approach.

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Spectrum characteristics and pump wavelengths of Nd_(3+) -doped double-clad fiber

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Chinese Science Bulletin 1997年第11期42卷 897-900页

作者： MING Hai, YANG Bao, DONG Xiaopeng, A. Fedotov, Xudong Xiao and M. M. T. Loy1. department of physics, {2. of Science and Technology of China, Hefei 2.002., China 2. department of physics, {2. of Science and Technology of Hong Kong, Hong Kong, China department of physics University of Science and Technology of China Hefei China department of physics University of Science and Technology of Hong Kong Hong Kong China

Nd3+ -doped double-clad fiber is a new type of fiber that has large *** large receivingarea compared with single-clad rare-earth-doped *** Nd3+-doped double-clad fiberpumped directly by laser-diode arrays can be manufactured into high-power fiber lasers,high-power superfluorescence sources and high-gain fiber amplifiers,and they will be applied

关键词： double-clad fiber optimum pump wavelength optical spectrum.

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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 2.0065, 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.

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FeS_(2. (pyrite) electrodeposition thin films and study of growth mechanism

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Science China(Technological Sciences) 2005年第6期48卷 601-611页

作者： DONG Youzhong1, ZHENG Yufeng1, ZHANG Xiaogang2. DUAN He1, SUN Yanfei1 & CHEN Yanhua1 1. department of physics, Xinjiang {2., Urumqi 830046, China 2. Institute of Applied Chemistry, Xinjiang {2., Urumqi 830046, China 1. department of physics Xinjiang University 830046 Urumqi China 2. Institute of Applied Chemistry Xinjiang University 830046 Urumqi China

Ferrous sulfide (FeS) thin films were initially electrodeposited on indium-tin oxide (ITO) substrates in the aqueous solution containing iron, sulfur elements and then annealed in the sulfur atmosphere. Thereby, we successfully obtained the single-phased iron pyrite (FeS2. thin films with good quality. The experimental parameters for electrodeposition and the post-growth thermal-dynamical conditions have been calculated so that more details about the effect of thermal-dynamical conditions on the micromechanism concerned with the iron pyrite crystal growth as well as the properties of the samples have been discussed.

关键词： electrodeposition, FeS2 (pyrite), thin films, growth dynamics.

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Doubly contracted CI method and applications

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Science China Chemistry 2004年第4期47卷 276-282页

作者： WANG Yubin1, HAN Huixian1, ZHAI Gaohong2.,SUO Bin1 & WEN Zheny1,2.1. Institute of Modern physics, Northwest university, Xian 710069, China 2. Laboratory of Physico-Inorganic Chemistry, {2. of Chemistry, Northwest university, Xian 710069,China Correspondence should be addressed to Wen Zhenyi 1. Institute of Modern physics Northwest University 710069 Xian China 2. Laboratory of Physico-Inorganic Chemistry Department of Chemistry Northwest University 710069 Xi’an China

Based on the hole-particle correspondence an approximate so-called doubly contracted CI scheme is proposed. Examples calculated based on the doubly contracted CI (DCCI) scheme show that the number of configurations after contraction is reduced by three orders of magnitude, and the computation time is reduced by an order of magnitude. The examples also show that compared with experiments the DCCI and uncontracted CI have similar and reasonable accuracy to some spectroscopic parameters.

关键词： doubly contracted CI hole-particle symmetry approximate MRCI

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