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Application of cathodoluminescence to zircon in FEG-EsEM

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Progress in Natural science:Materials International 2006年第9期16卷 919-924页

作者： CHEN Li , XU Jun and sU Li (Electron Microscopy laboratory, school of physics, peking university, {3., china Geology Experimental Center, china university of Geoscience, beijing 100083. china) Electron Microscopy laboratory School of Physics Peking University Beijing 100871 China Geology Experimental Center China University of Geoscience Beijing 100083 China

Cathodoluminescence (CL) image analysis of zircon is a key step of mineral micro-area compositional investigation and U-(Th)-Pb dating. We introduce a system consisting of field emission EsEM and high performance cathodoluminescence. This system has obvious advantages in imaging resolution and CL spectrum. We acquired some zircon CL images and spectra to demonstrate the ability of this system. Our results show that this system has a great potential application to characterize and identify the genesis of zircon.

关键词： zircon cathodoluminescence EsEM.

A new simulated annealing method of designing NMR biplanar shim coils

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Progress in Natural science:Materials International 2006年第7期16卷 747-752页

作者： QI Feng, TANG Xin, WANG Weimin, sHEN Yifei, LIU shaopo and JIANG Zhongde ( key laboratory for Quantum Information and Measurements of Ministry of Education, school of Electronics Engineering & Computer science, peking university, {3., china Institute of Heavy Ion physics, and beijing key laboratory of Medical physics and Engineering, Physical school, peking university, {3., china) [a]key laboratory for Quantum Information and measurements of ministry of Education School of Electronics Engineering & Computer Science Peking University Beijing China [b]Institute of Heavy Ion physics and Beijing Key laboratory of Medical Physics and Engineering Physical School Peking University Beijing China

A new sA (simulated annealing) method is presented for the design of longitudinal shim coils for NMR (nuclear magnetic resonance) equipment. First, AGL (adaptive Gauss-Lobatto) quadrature used by the traditional sA method is analyzed. Two kinds of complete elliptic integrals are introduced to integrate the spatial magnetic field, which increases the computing speed by 13. 3.times. Then, the system energy calculation is extended to the field of the z-axis. The results illustrate that the coil-set efficiency designed by the new sA method is 15 % higher than that of the traditional one, and the field inhomogeneity is reduced from 1.20 % to 0.49 % . Finally, a prototype of coil assembly for NMR rock-core analyzer is built, and the experimental results are in good agreement with the theoretically calculated results.

关键词： NMR shim coil design simulated-annealing method complete elliptic integral.

An esnake model for medical image segmentation

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Progress in Natural science:Materials International 2005年第5期15卷 424-429页

作者： Lv Hongyu1, YUAN Kehong2, BAO shanglian1, ZU Donglin1 and DUAN Chaijie1*(1. The Research Center for Tumor Diagnosis and Therapeutical physics & beijing key {3. of Medical physics and Engineering, beijing 100871, china 2. key {3. of Pure and Applied Mathematics, school of Mathematical sciences, peking university, beijing 100871, china) The Research Center for Tumor Diagnosis and Therapeutical physics & beijing key {3. of Medical physics and Engineering Beijing 100871 China key laboratory of Pure and Applied Mathematics School of Mathematical Sciences Peking University Beijing 100871 China

A novel scheme of external force for detecting the object boundary of medical image based on snakes (active contours) is introduced in the paper. In our new method, an electrostatic field on a template plane above the original image plane is designed to form the map of the external force. Compared with the method of Gradient Vector Flow (GVF), our approach has clear physical meanings. It has stronger ability to conform to boundary concavities, is simple to implement, and reliable for shape segmenting. Additionally, our method has larger capture range for the external force and is useful for medical image preprocessing in various applications. Finally, by adding the balloon force to the electrostatic field model, our snake is able to represent long tube-like shapes or shapes with significant protrusions or bifurcations, and it has the specialty to prevent snake leaking from large gaps on image edge by using a two-stage segmentation technique introduced in this paper. The test of our models proves that our methods are robust, precise in medical image segmentation.

关键词： image segmentation esnake external force electrostatic field balloon force.

Genetic and logic networks with the signal-inhibitor-activator structure are dynamically robust

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Progress in Natural science:Materials International 2006年第12期16卷 1329-1336页

作者： LI Fangting** and TAN Ning(school of physics and Centre for Theoretical Biology, peking university, beijing 100871, {3.) [a]school of physics and Centre for Theoritical Biology Peking University Beijing China

The proteins, DNA and RNA interaction networks govern various biological functions in living cells, these networks should be dynamically robust in the intracellular and environmental fluctuations. Here, we use Boolean network to study the robust structure of both genetic and logic networks. First, sOs network in bacteria E. coli, which regulates cell survival and repair after DNA damage, is shown to be dynamically robust. Comparing with cell cycle network in budding yeast and flagella network in E. coli, we find the signal-inhibitor-activator (sIA) structure in transcription regulatory networks. second, under the dynamical rule that inhibition is much stronger than activation, we have searched 3.node non-self-loop logical networks that are dynamically robust, and that if the attractive basin of a final attractor is as large as seven, and the final attractor has only one active node, then the active node acts as inhibitor, and the sIA and signal-inhibitor (sI) structures are fundamental architectures of robust networks. sIA and sI networks with dynamic robustness against environment uncertainties may be selected and maintained over the course of evolution, rather than blind trial-error testing and being an accidental consequence of particular evolutionary history. sIA network can perform a more complex process than sI network, and sIA might be used to design robust artificial genetic network. Our results provide dynamical support for why the inhibitors and sIA/sI structures are frequently employed in cellular regulatory networks.

关键词： genetic network signal-inhibitor-activator (sIA) structure Boolean network model dynamical robust.

Estimating surface evapotranspiration using combined MODIs and CBERs-02 data

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science china(Technological sciences) 2005年第S2期48卷 145-160页

作者： XIN Xiaozhou1,2, LIU Qinhuo1, TANG Yong1,3. TIAN Guoliang1, GU Xingfa1, LI Xiaowen1,2, ZHENG Hongsheng4 & CHEN Jiayi4 1. state key laboratory of Remote sensing science, Institute of Remote sensing Applications, Chinese Academy of sciences, beijing 100101, {3. 2. Research Center for Remote sensing and GIs, Department of Geography, beijing Normal university, beijing 100875, {3. 3. Graduate university of Chinese Academy of sciences, beijing 10003., {3. 4. Department of Atmospheric physics, peking university, {{13., {3. 1. state key laboratory of Remote sensing science Institute of Remote Sensing Applications Chinese Academy of Sciences 100101 Beijing China2. Research Center for Remote Sensing and GIS Department of Geography Beijing Normal University 100875 Beijing China3. Graduate University of Chinese Academy of Sciences 100039 Beijing China4. Department of Atmospheric Physics Peking University 100871 Beijing China

spatial scale error is one of the most serious problems in the estimates of land surface heat fluxes of sensible and latent from satellite-borne data such as MODIs 1km resolution reflectance and emissive data. One of the feasible and economic ways to decrease the spatial scale error is to use high resolution land use class data together with the MODIs data. CBERs-02 data were used to produce land use class of Baiyangdian area, Hebei Province, china in the autumn of 2004. The area ratio of each class in MODIs pixel was calculated, and used to derive the heat fluxes of the mixed pixel. The results showed that the estimated heat fluxes of soil, sensible and latent have been changed remarkably after using the high resolution land class data. It could be concluded from the comparison between simulated and ground-measured fluxes as well as the theoretical analysis that high resolution land class data are useful to diminishing the scale error of heat fluxes estimated from low resolution satellite data.

关键词： surface evapotranspiration spatial scale error MODIs CBERs land class.

selected issues at the interface between nuclear physics and astrophysics as well as the standard model

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中国科学：物理学、力学、天文学英文版 2011年第S1期54卷 119-123页

作者： MENG Jie1,2,3. NIU ZhongMing1, LIANG HaoZhao1 & sUN BaoHua2,4 1state key laboratory of nuclear {3. and Technology, school of {3., peking university, beijing 100871, china 2school of {3. and nuclear Energy Engineering, Beihang university, beijing 100191, china 3.epartment of {3., university of stellenbosch, stellenbosch, south Africa 4Justus-Liebig-Universita¨t Giessen, Heinrich-Buff-Ring 14, Giessen 3.3.2, Germany 1. state key laboratory of nuclear {3. and Technology School of Physics Peking University Beijing 100871 China 2. school of physics and nuclear Energy Engineering Beihang University Beijing 100191 China 3. Department of physics University of Stellenbosch Stellenbosch South Africa 4. Justus-Liebig-Universit?t Giessen Heinrich-Buff-Ring 14 Giessen 35392 Germany

The density functional theory (DFT) with a minimal number of parameters allows a very successful phenomenological description of ground state properties of nuclei all over the periodic table. The recent developments on the application of the covariant density functional theory as well as its extensions by the group in beijing for a series of interests and hot topics in nuclear astrophysics and nuclear structure are reviewed, including the rapid neutron-capture process, Th/U chronometer, and isospin corrections for superallowed β transitions.

关键词： rapid neutron-capture process nuclear chronometer isospin symmetry-breaking corrections

A novel method for evaluating and improving the 1H-MRsI glioma data quality

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Progress in Natural science:Materials International 2005年第8期15卷 765-768页

作者： YUAN Kehong 1,2, LU Hongyu2, BAO shanglian2*, CHEN Qiansheng1, LI shaowu3.and DUAN Chaijie2(1. key laboratory of Pure and Applied Mathematics, school of Mathematical sciences, beijing 100871, {3. 2. The Research Center for Tumor Diagnosis and Therapeutical physics & the beijing key laboratory of Medical physics and Engineering, peking university, beijing 100871, {3. 3. The Tian Tan Hospital, beijing 100050, {3.) key laboratory of Pure and Applied Mathematics School of Mathematical Sciences Beijing 100871 China. The Research Center for Tumor Diagnosis and Therapeutical physics & the beijing key {3. of Medical physics and Engineering Peking University Beijing 100871 China. The Tian Tan Hospital Beijing 100050 China

Metabolic information obtained by proton magnetic resonance spectroscopic imaging (1H-MRsI) has been approved to be a powerful tool to identify either benign or malignant glioma, as well as to confirm the tumor level. However, 1H-MRsI data are affected by various factors, such as the thermal noise, eddy currents, susceptibility artifacts, and rigid body motion. To get accurate quantitative metabolic information, the key problem is to assess the 1H-MRsI data quality. In this paper, we introduce a new evaluating system to filter the data, and a new method, called wavelet denoising method, to improve the data quality under the evaluating system. Experimental results on 1H-MRsI glioma data demonstrate that preprocessing is prerequisite and the proposed algorithm with evaluating system is effective.

关键词： 1H-MRsI evaluating system glioma data quality wavelet denoising

Response synchronization: New progress in brain-visual information processing

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Chinese science Bulletin 1999年第16期44卷 1447-1458页

作者： ZHAO songnian, XIONG Xiaoyun, YAO Guozheng and GUO Aike1. state key laboratory of Atmospheric Boundary Layer physics and Atmospheric Chemistry , Institute of Atmospheric physics , Chinese Academy of sciences , beijing 100029, china 2. Commission of the National Natural science Foundation of china , beijing 100083. china 3. The Center of Information science , peking university, beijing 100871, china 4. Open laboratory of Visual Information Processing , Institute of Biophysics , Chinese Academy of sciences , beijing 100101, china state key laboratory of Atmospheric Boundary Layer physics and Atmospheric Chemistry Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Commission of the National Natural science Foundation of china Beijing China The Center of Information science Peking University Beijing China Open laboratory of Visual Information Processing Institute of Biophysics Chinese Academy of Sciences Beijing China

studies on brain-vision have entered a new stage, after the stimulus-induced y synchronized oscillation of neuron group activities have been discovered in cat primary visual cortex. Naturally, how to understand the visual system became a very important methodological problem. From aspects such as information processing, nonlinear dynamics and neuronal network, some primary problems in vision studies have been deeply discussed, which are

关键词： neuron group (neural population) synchro-oscillation computational theory of vision response synchroniza-tion.

Convergence for Imaginary Time step evolution in the Fermi and Dirac seas

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science china(physics,Mechanics & Astronomy) 2010年第2期53卷 327-330页

作者： LI FangQiong1,ZHANG Ying2 & MENG Jie2,3.4 1Guizhou university for Nationalities,Guiyang 550025,china 2state key Lab Nucl. Phys. & Tech.,school of {3.,peking university,beijing 100871,china 3.chool of {3. and nuclear Energy Engineering,Beihang university,beijing 100191,china 4Department of {3.,university of stellenbosch,stellenbosch,south Africa 1. Guizhou university for Nationalities Guiyang 550025 China2. State Key Lab Nucl. Phys. & Tech. School of Physics Peking University Beijing 100871 China3. School of Physics and Nuclear Energy Engineering Beihang University Beijing 100191 China4. Department of Physics University of Stellenbosch Stellenbosch South Africa

The convergence for the Imaginary Time step (ITs) evolution with time step is investigated by performing the ITs evolution for the schrdinger-like equation and the charge-conjugate schrdinger-like equation deduced from Dirac equation for the single proton levels of 12C in both the Fermi and Dirac seas. For the guaranteed convergence of the ITs evolution to the "exact" results,the time step should be smaller than a "critical" time step Δtc for a given single-particle level. The "critical" time step Δtc is more sensitive to the quantum numbers |κ| than to the energy of the single-particle level. For the single-particle levels with the same κ,their "critical" time steps are in the same order. For the single-particle levels with similar energy,a relatively small (large) "critical" time step for larger (smaller) |κ| is needed. These conclusions can be used in the future self-consistent calculation to optimize the evolution procedure.

关键词： Dirac equation schrdinger-like equation Imaginary Time step method convergence