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Biased Brownian Motion Driven by Fluctuating Temperature

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Chinese Physics Letters 1997年第5期14卷 332-335页

作者： li yu-xiao Institute of High Energy Physics Chinese Academy of SciencesBeijing 100039 Department of Physics Zhengzhou UniversityZhengzhou 450052

Biased Brownian motion in a periodic potential with fluctuating temperature of thermal bath is *** general expression of stationary probability current is *** necessary condition for biased Brownian motion is the comb... 详细信息

关键词： potential. Brownian fluctuating

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

Application of numerical simulation to flow induced corrosion in flowing seawater system

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中国有色金属学会会刊：英文版 2004年第z1期14卷 439-442页

作者： liU Jing-jun liN yu-zhen YONG Xing-yue li xiao-yu School of Materials Science and Engineering Beijing University of Chemical Technology Beijing 100029 China School of Materials Science and Engineering Beijing University of Chemical Technology Beijing 100029 China School of Materials Science and Engineering Beijing University of Chemical Technology Beijing 100029 China School of Materials Science and Engineering Beijing University of Chemical Technology Beijing 100029 China

An established model was presented as a new kind of means for investigating flow induced corrosion. In this method the near-wall hydrodynamic parameters including wall shear stress τ and mass transfer coefficient k near the wall of materials can be numerically calculated, and combining corrosive kinetics tested by experiments, the corrosion rates can be also calculated accurately. The flow induced corrosion mechanism was further verified by numerical results in this model, and the various corrosion phenomena were explained. The modelled results also show that the ability to accurately utilize numerical method to study flow induced corrosion strongly to some extent depends on material corrosive kinetics processes tested by experiments.

关键词： flow induced corrosion numerical simulation near-wall hydrodynamic parameters mechanism

Soil nutrient loss due to tuber crop harvesting and its environmental impact in the North China Plain

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Journal of Integrative Agriculture 2016年第7期15卷 1612-1624页

作者： yu Han-qing li Yong ZHOU Na Adrian Chappell li xiao-yu Jean Poesen Agricultural Clean Watershed Research Group Institute of Environment and Sustainable Development in AgricultureChinese Academy of Agricultural Sciences(CAA S)Beijing 100081P.R.China CSIRO Land&Water National Research Flagship Canberra ACT 2601Australia Division of Geography KU LeuvenHeverlee 3001Belgium

Soil loss due to crop harvesting （SLCH） is a soil erosion process that signiifcantly contributes to soil degradation in crop-lands. However, little is known about soil nutrient losses caused by SLCH and its environmental impacts. In the North China Plain area, we measured the losses of soil organic carbon （SOC） and nitrogen as wel as phosphorus due to SLCH and assessed their relationship with soil particle size composition, agronomic practices and soil moisture content. Our results show that the losses by harvesting potato of SOC, total nitrogen （TN）, available nitrogen （AN）, available phosphorus （AP） and total phosphorus （TP） were 1.7, 1.8, 1.8, 15.9 and 14.1 times compared by harvesting sweet potato, respectively. The variation of SOC, N and P loss by SLCH are mainly explained by the variation of plant density （PD）（17–50%）, net mass of an individual tuber （Mcrop/p）（16–74%）, soil clay content （34–70%） and water content （19–46%）. Taking into account the current sewage treatment system and the ratio of the nutrients adhering to the tubers during transportation from the ifeld （NTRP/SP）, the loss of TN and TP by harvesting of potato and sweet potato in the North China Plain area amounts to 3% N and 20% P loads in the water bodies of this region. The fate of the exported N and P in the sewage treatment system ultimately controls the contribution of N and P to the polution of lakes and rivers. Our results suggest that a large amount of SLCH-induced soil nutrient export during transportation from the ifeld is a potential polutant source for agricultural water for vast planting areas of tuber crops in China, and should not be overlooked.

关键词： soil nutrient losses potato sweet potato crop harvesting water polution

Effects of carbon on Pr_(0.15)Tb_(0.30)Dy_(0.55)Fe_(1.85) compound

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Rare Metals 2006年第z2期25卷 220-222页

作者： liU Heyan li Yangxian yu xiao li Songtao MENG Xiangxi XU Xuewen School of Material Science and Engineering Hebei University of Technology Tianjin 300130 China School of Material Science and Engineering Hebei University of Technology Tianjin 300130 China School of Material Science and Engineering Hebei University of Technology Tianjin 300130 China Department of Physics North China Electric Power University Baoding 071003 China School of Material Science and Engineering Hebei University of Technology Tianjin 300130 China School of Material Science and Engineering Hebei University of Technology Tianjin 300130 China

The structure, Curie temperature and magnetostriction of Pr0.15Tb0.30Dy0.55Fe1.85Cx (x=0-0.1) compounds were investigated by X-ray diffraction, a vibrating sample magnetometer and a standard strain technique. All the samples show entirely MgCu2-type Laves phase structure. The lattice parameter and Curie temperature increase with C content increasing. The magnetostriction at high magnetic field shows maximum value at x=0.05.

关键词： magnetostriction Pr0.15Tb0.3Dy0.55Fe1.85 Laves phase

Synthetic Characteristics Associated with HIV Diagnosis through Voluntary HIV Testing among HIV-positive People with Non-marital and Non-commercial Heterosexual Transmission in China

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Biomedical and Environmental Sciences 2019年第6期32卷 459-464页

作者： yu Qiu Yan yu Shi Cheng XU Peng YANG Juan li xiao yu LU Fan National Center for STD/AIDS Prevention and Control Chinese Center for Disease Control and Prevention Beijing 102206 China Office of Epidemiology Chinese Center for Disease Control and Prevention Beijing 102206 China Department of Cadre Health Care Beijing Jishuitan Hospital The Fourth Medical College of Peking University Beijing 100035 China

The Joint United Nations program on HIV/AIDS reported that 53% of new infections globally in 2017 were beyond key populations and their sexual *** this report, although only 16% in Asia and the Pacific were people living with HIV (PLHIV) who did not report any HIV-risk behaviors (mainly including injective drug use, men who have sex with men, sexual workers, and their dients), increasing diag no sed cases who reported their own transmission as non-marital and non-commercial heterosexual con tact (non-M&C sex, defi ned as those heterosexuals who have unpaid sex with any other sexual partners whom they have never married) in China have indicated that the HIV epidemic is spreading to the general population by the bridge of key populations.

关键词： Synthetic Characteristics HIV

Investigation of Spontaneous Condensation of an Amino Acid Based Amphiphile on Cast Film by in situ Transmission FT-IR Spectroscopy

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Chinese Chemical Letters 2005年第12期16卷 1637-1640页

作者： Hai Yan WANG Yan Mei li Yi xiao yu Fen ZHAO The Key Laboratory of Bioorganic Phosphorus Chemistry ＆ Chemical Biology （Ministry of Education） Department of Chemistry Tsinghua University Beijing 100084

The spontaneous condensation of the amphiphilic N-（O,O-dihexadecyl）phosphorylalanine on the cast film was observed by in situ investigation of transmission infrared spectroscopy The particular orientation and ordered packing of the monomers within the multilayers of the cast film is concluded to attribute to the spontaneous condensation between the monomers.

关键词： Amphiphile cast film condensation FT-IR N-(O O-dihexadecyl)phosphoryl alanine

Application of Wavelet Transform in the Prediction of Navel Orange Vitamin C Content by Near-Infrared Spectroscopy

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Agricultural Sciences in China 2007年第9期6卷 1067-1073页

作者： XIA Jun-fang li xiao-yu li Pei-wu MA Qian DING xiao-xia Engineering and Technology Department Huazhong Agricultural University Wuhan 430070 P.R.China Oil Crops Research Institute Chinese Academy of Agricultural Sciences Wuhan 430062 P.R.China College of life Science and Technology Huazhong Agricultural University Wuhan 430070 P.R. China

This study was to search for an approach for rapid measurement of orange vitamin C （Vc） content. By using different decomposing levels of Daubechies 3 wavelet transform, the near-infrared spectra signals obtained from intact fruits of 100 navel orange samples were denoised, and the results of the predicted Vc contents for the corresponding samples determined by the reconstructed spectra after denoising were validated by means of PLS-CV （partial least squared-cross validation）. It was shown that the prediction effects verified by PLS-CV analysis varied when different wavelet transform decomposing levels were employed. At the wavelet decomposing level 4, the best prediction effect was obtained, with the correlation coefficient R between the prediction and true values being 0.9574 and the expected variance RMSECV being as low as 3.9 mg 100 g^-1. Furthermore, the 11 different approaches for the pretreatment of the near-infrared spectrum were compared. It was found that the calibration model established by PLS using spectra pretreated by wavelet transform denoising provided the best prediction for Vc content, exhibiting the highest correlation between the prediction and true values by cross validation. In conclusion, the near infrared spectral model denoised by means of wavelet transform can be used for accurate, rapid, and nondestructive quantitative analysis on navel orange Vc content.

关键词： navel orange near infrared spectroscopy wavelet denoising partial least square