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Error Thresholds in Single-Peak Gaussian Distributed Fitness Landscapes

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Communications in Theoretical Physics 2007年第4X期48卷 763-768页

作者： FENG Xiao-Li gu jian-zhong LI Yu-Xiao ZHUO Yi-zhong School of Physical Engineering Zhengzhou University Zhengzhou 450052 Ghina China Institute of Atomic Energy P.O. Box 275(18) Beijing 102413 China

Based on the Eigen and Crow-Kimura models with a single-peak fitness landscape, we propose the fitness values of all sequence types to be Gausslan distributed random variables to incorporate the effects of the fluctuations of the fitness landscapes （noise of environments） and investigate the concentration distribution and error threshold of quasispecies by performing an ensemble average within this theoretical framework. We find that a small fluctuation of the fitness landscape causes only a slight change in the concentration distribution and error threshold, which implies that the error threshold is stable against small perturbations. However, for a sizable fluctuation, quite different from the previous deterministic models, our statistical results show that the transition from quasi-species to error catastrophe is not so sharp, indicating that the error threshold is located within a certain range and has a shift toward a larger value. Our results are qualitatively in agreement with the experimental data and provide a new implication for antiviral strategies.

关键词： quasi-species error threshold Gaussian distributed fitness landscape

Relaxation Property and Stability Analysis of the Quasispecies Models

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Communications in Theoretical Physics 2009年第10期52卷 726-734页

作者： FEGN Xiao-Li LI Yu-Xiao gu jian-zhong ZHUO Yi-zhong School of Physical Engineering Zhengzhou University Zhengzhou 450052 China Center for Computational and System Biology Institute of Biophysics Chinese Academy of Science Beijing 100101 China China Institute of Atomic Energy P.O. Box 275（18） Beijing 102413 China Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou 730000 China

The relaxation property of both Eigen model and Crow-Kimura model with a single peak fitness landscape is studied from phase transition point of view. We first analyze the eigenvalue spectra of the replication mutation matrices. For sufficiently long sequences, the almost crossing point between the largest and seeond-largest eigenvalues locates the error threshold at which critical slowing down behavior appears. We calculate the critical exponent in the limit of infinite sequence lengths and compare it with the result from numerical curve fittings at sufficiently long sequences. We find that for both models the relaxation time diverges with exponent 1 at the error （mutation） threshold point. Results obtained from both methods agree quite well. From the unlimited correlation length feature, the first order phase transition is further confirmed. Finally with linear stability theory, we show that the two model systems are stable for all ranges of mutation rate. The Igigen model is asymptotically stable in terms of mutant classes, and the Crow-Kimura model is completely stable.

关键词： relaxation time critical exponent error threshold

Tensor Effect on Bubble Nuclei

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Chinese Physics Letters 2011年第10期28卷 62-65页

作者： WANG Yan-Zhao gu jian-zhong ZHANG Xi-Zhen DONG jian-Min China Institute of Atomic Energy P.O.Box 275(10)Beijing 102413 Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Accelerator of LanzhouLanzhou 730000 School of Nuclear Science and Technology Lanzhou UniversityLanzhou 730000

In the framework of the Hartree–Fock–Bogoliubov(HFB)approach with Skyrme interactions SLy5+T,SLy5+Tw and several sets of TIJ parametrizations,*** Skyrme interaction parametrizations including the tensor terms,the proton density distribution in ^(34)Si and ^(46)Ar nuclei is calculated with and without the tensor *** is shown that the bubble effect in ^(34)Si does not depend a great deal on the Skyrme parametrization and the proton density distribution in ^(34)Si is hardly influenced by the tensor *** to ^(46)Ar,the SLy5+Tw parametrization favors the formation of the bubble structure due to the inversion between the 2s_(1/2) and 1d_(3/2) orbits(2s_(1/2)–1d_(3/2) inversion).The inversion mechanism induced by the SLy5+Tw interaction is analyzed based on the proton single−particle spectra obtained from the SLy5 and SLy5+Tw interactions as well as the wave functions of the 2s_(1/2) and 1d_(3/2) states.

关键词： force tensor bubble

Classical Dynamics of a Nucleon in Heavy Nuclei

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Chinese Physics Letters 1998年第5期15卷 318-320页

作者： gu jian-zhong ZHAO En-guang ZHUO Yi-zhong WU Xi-zhen ZONG Hong-shi Institute of Theoretical Physics Chinese Academy of SciencesBeijing 100080 China Institute of Atomic Energy Beijing 102413

Within the framework of the two-center shell model,the classically dynamical behaviour of a nucleon in heavy nuclei is investigated when nuclear shape parameters are changed *** is found that there is a good quantum-classical correspondence of nucleonic regular(chaotic)motion so that Bohigas,Giannoni and Schmit conjecture is confirmed once again.

关键词： behaviour chaotic correspondence

Yrast Properties of Dysprosium Isotopes in the Double Mid-Shell Region

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Chinese Physics Letters 2010年第1期27卷 78-81页

作者：邹文华顾建中 School of Nuclear Engineering and Technology East China Institute of Technology Fuzhou 344000 China Institute of Atomic Energy PO Box 275(18) Beijing 102413 Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou 730000

The yrast bands of the even-even dysprosium isotopes 164-174Dy are calculated up to high angular momentum 34h based on the projected shell model. Our calculations are in good agreement with the experiments quantitatively. They predict that an energy minimum of the first 2＋ state in these isotopes exists around the neutron mid-shell N=104, implying the maximum collectivity in 66170Dy104, however, the energy ratio R4=E（4＋1）/E（2＋1） reaches a saturation at N=102. Meanwhile, the back-bending plots of these yrast bands are examined carefully. It is found that the sharpness of the back-bending has a gradual shift along the dysprosium isotopic chain, namely, the slope of the back-bending becomes steeper as the neutron number increases except for an irregularity of a decreasing dip angle in the double mid-shell nucleus 170Dy. We suggest that 170Dy undergoes a dual alignment with midshell high-j protons and neutrons aligning simultaneously at spin I≈16h, which probably results in the distinctive back-bending behavior.

关键词： DYSPROSIUM ISOTOPES ANguLAR momentum (Nuclear physics) ENERGY levels (Quantum mechanics) NEUTRONS NUCLEAR models

Level Statistics for the Nilsson Single-Particle Levels

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Chinese Physics Letters 2010年第3期27卷 52-55页

作者：陈芳祁周先荣顾建中 Department of Physics and Institute of Theoretical Physics and Astrophysics Xiamen University Xiamen 361005 China Institute of Atomic Energy P.O. Box 275(18) Beijing 102413

We perform level statistics of the Nilsson single-particle levels. The effects of the l2 and l ＆#12539; s; s terms are discussed as well as their interplay with the deformations. The results show that when the l2 term is added to the harmonic oscillator potential, chaotic motion occurs. The strength ranges of the l2 term in which chaotic motion exists are related to the deformation of the harmonic oscillator potential. The calculations of the localization length in different bases demonstrate that it is the spherical or axial symmetries that govern the chaotic motion. The degree of chaoticity increases significantly with the l ＆#12539; s; s term included.

关键词： Nuclear physics

Analysis of the urinary peptidome associated with Helicobacter pylori infection

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World Journal of Gastroenterology 2011年第5期17卷 618-624页

作者： Di Xiao Fan-Liang Meng Li-Hua He Yi-Xin gu jian-zhong Zhang National Institute for Communicable Disease Controland Prevention Chinese Center for Disease Control and Pre-vention Beijing 102206 China

AIM： To investigate the relationship between urinary peptide changes and Helicobacter pylori （H. pylorl） infection using urinary peptidome profiling. METHODS： The study was performed in volunteers （n = 137） who gave informed consent. Urinary peptides were enriched by magnetic beads based weak cation exchange chromatography＇and spectrums acquired by matrix-assisted laser desorption/ionization time-of-flight （MALDI-TOF） mass spectrometry （MS）. ClinProTools bioinformatics software was used for statistical analysis and the recognition of peptide patterns. The marker peptides were identified by LTQ Obitrap XL tandem MS. RESULTS： Approximately 50 proteins or peptides which loaded onto the magnetic beads were detected by MAL-DI-TOF MS. By optimizing the parameters of the model, the Genetic Algorithm model had good recognition capability （97%） and positive predictive value （94%）. Based on the model, 2 markers with molecular masses of 6788 and 1912 Da were found that differentiated between H. pylori positive and negative volunteers. The m/z 1912 sequence was parsed as SKQFTSSTSYN- RGDSTF. The peptide was identified as isoform 1 of the fibrinogen a chain precursor, whose concentration in urine was markedly higher in H. pylori infected volunteers than in H. pylori non-infected ones. CONCLUSION： The appearance of urinary fibrinogen degradation products is caused by an active H. pyloriinduced process.

关键词： Urinary peptidome profiling MB-matrix-assisted laser desorption/ionization time-of-flight massspectrometry Helicobacter pylori Fibrinogen degrada-tion products

Yrast Properties of Dysprosium Isotopes in Double Mid-shell Region

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Yrast Properties of Dysprosium Isotopes in Double Mid-shell ...

Structure of Zr Isotopes Near N=Z Line

作者： ZOU Wen-hua gu jian-zhong

The yrast bands of the even-even dysprosium isotopes Dy are calculated up to high angular momentum 34h based on the projected shell *** calculations are in good agreement with experiments *** predict that an energy minimum of the 2 state in these isotopes exists around the neutron mid-shell N=104,implying the maximum collectivity in Dy,however,the energy

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Structure of Zr Isotopes Near N=Z Line