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Probability parametric imaging with DCE-MRI data to identify prostate cancer in the peripheral zone

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Progress in Natural science:Materials International 2006年第9期16卷 948-953页

作者： HUANG Xinrui, WANG Qiang, XU Yufeng, WANG Xiaoying and BAO shanglian ( The key laboratory of Medical physics and Engineering, {3., beijing 100871, china The Medical school of {3., beijing 100083. china 3. The First Hospital of {3., beijing 10003., china) [a]The key laboratory of Medical physics and Engineering Peking University Beijing China [b]The Medical school of peking university Beijing China [c]The First Hospital of peking university Beijing China

To quantitatively analyze prostate dynamic contrast-enhanced magnetic resonance images (DCE-MRI), a retrospective study was carried out to construct a mathematical model to predict whether a lesion is cancerous or not. With known diagnosis of 52 re-gions-of-interest (10 malignant, 26 benign and 16 normal) in peripheral zone (PZ) of prostate from 18 patients undergoing needle biopsy and 8 normal volunteers, we combined feature parameters (k1, k2 and tp) from the linear-slope model with logistic regression to determine the statistical probability model. Prostate cancerous probability maps were derived using the model on each subject to examine the correlation between the model-based prediction and the known diagnosis. Compared the model prediction results of 52 regions-of-interest with the histopathologic results, the total agreement rate was 90.4 % ; the agreement rate was 60 % for the malignant and 97. 6 % for the nonmalignant. The diagnostic results only referencing the probability maps by two radiologists showed a high agreement in tissue characteristics and lesion location with the combining results from other diagnostic techniques such as PsA (prostate specific antigen) level and MRs (magnetic resonance spectroscopy) .

关键词： time-intensity curve prostate DCE-MRI logistic regression probability parametric image.

Kinetic characteristics of continuous flow polymerase chain reaction chip: A numerical investigation

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science china(Technological sciences) 2010年第7期53卷 1967-1972页

作者： WANG shiYing1 & WANG Wei2,3.1 school of physics, peking university, beijing 100871, {3. 2 Institute of Microelectronics, peking university, beijing 100871, {3. 3.National key laboratory of science and Technology on Micro/Nano Fabrication, beijing 100871, {3. 1. school of physics Peking University Beijing 100871 China2. Institute of Microelectronics Peking University Beijing 100871 China3. National Key Laboratory of Science and Technology on Micro/Nano Fabrication Beijing 100871 China

Continuous flow PCR (polymerase chain reaction) chip holds impressive advantages compared to micro chamber PCR chip. In order to have better understanding of kinetic characteristics of continuous flow PCR chip, a comprehensive mathematical model is presented in this paper, including melting, annealing and extension phases of a typical PCR process which has the essence of a convection-diffusion-reaction system. Using this model, we can simulate the PCR process in series of reaction cycles. Numerical results show that the average sample velocity plays a significant role in affecting the amplification efficiency. Also, appropriate combination of the PCR mixture is important for high-quality DNA amplification. Giving a large initial DNA concentration range, the continuous flow PCR scheme holds excellent real-time detection ability theoretically. The present numerical model bridges the temperature distribution to the real DNA amplification, and thereby is able to successfully predict continuous flow PCR properties which are important for the chip design.

关键词： continuous flow PCR chip numerical simulation convection-diffusion-reaction system

Experimental measurement of growth patterns on fossil corals:secular variation in ancient Earth-sun distances

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Chinese science Bulletin 2010年第35期55卷 4010-4017页

作者： ZHANG WeiJia1,3.4,LI ZhengBin2,3.& LEI Yang1 1 Department of physics,peking university,beijing 100871,{3. 2 Department of Electrical Engineering and Computer science,peking university,beijing 100871,{3. 3.state key laboratory of Advanced Optical Communication systems & Networks,peking university,beijing 100871,{3. 4 Committee of Yuanpei Honors Program,peking university,beijing 100871,{3. Department of physics Peking University Beijing 100871 China state key laboratory of Advanced Optical Communication systems & Networks Peking University Beijing 100871 China Committee of Yuanpei Honors Program Peking University Beijing 100871 China Department of Electrical Engineering and Computer science Peking University Beijing 100871 China

In recent years,much attention has been given to the increase in the Earth-sun distance,with the modern rate reported as 5-15 m/cy on the basis of astronomical ***,traditional methods cannot measure the ancient leaving rates,so a myriad of research attempting to provide explanations were met with unmatched *** this paper we consider that the growth patterns on fossils could reflect the ancient Earth-sun *** mechanical analysis of both the Earth-sun and Earth-Moon systems,these patterns confirmed an increase in the Earth-sun *** a large number of well-preserved specimens and new technology available,both the modern and ancient leaving rates could be measured with high precision,and it was found that the Earth has been leaving the sun over the past 0.53.billion *** Earth's semi-major axis was 146 million kilometers at the beginning of the Phanerozoic Eon,equating to 97.6% of its current *** modern leaving rates are 5-14 m/cy,whereas the ancient rates were much *** results indicate a special expansion with an average expansion coefficient of 0.57H0 and deceleration in the form of Hubble *** the basis of experimental results,the Earth's semi-major axis could be represented by a simple formula that matches fossil measurements.

关键词：地球太阳古代距离生长模式实验石珊瑚量化

simulation of g factor for size optimization and coupling in phased array coil design

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Progress in Natural science:Materials International 2006年第2期16卷 120-124页

作者： sONG Xiaoyu, ZHANG Hongjie, WANG Le, BAO shanglian, sUN Yanrong and ZU Donglin (beijing key laboratory of Medical {3. & Engineering, peking university, beijing 100871, china {3. school, peking university, beijing 100871, china) [a]beijing key Labaratory of Medical physics & Engineering Peking University Beijing China [b]physics school Peking University Beijing China

The effect of geometric parameters of the coil element in an array on signal-to-notse ratio (sNR) and g factor of parallel imaging are analyzed, and the optimal parameters for the maximal sNR and minimal g factor are also given in this paper. In addition, the effects of coupling on sNR and g factor have been analyzed. The test results indicate that g factor for parallel imaging is greatly increased and sNR is decreased for coupling. According to the optimization, a six-channel parallel coil has been designed for torso imaging.

关键词： MRI phased array coil sENsE parallel imaging.

X-ray flares of γ-ray bursts: Quakes of solid quark stars?

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science china(physics,Mechanics & Astronomy) 2009年第2期52卷 315-320页

作者： XU RenXin1 & LIANG EnWei2 1 school of physics and state key laboratory of {3. physics and Technology, peking university, beijing 100871, china 2 Department of physics, Guangxi university, Nanning 53.004, china 1. school of physics and state key laboratory of {3. physics and Technology Peking University Beijing 100871 China 2. Department of physics Guangxi University Nanning 530004 China

A star-quake model is proposed to understand X-ray flares of both long and short γ-ray bursts (GRBs) in a solid quark star regime. Two kinds of central engines for GRBs are available if pulsar-like stars are actually (solid) quark stars, i.e., the sNE-type GRBs and the sGR-type GRBs. It is found that a quark star could be solidified about 103.to 106 s later after its birth if the critical temperature of phase transi- tion is a few Metga-electron-volts, and then a new source of free energy (i.e., elastic and gravitational ones, rather than rotational or magnetic energy) could be possible to power GRB X-ray flares.

关键词： γ-rays bursts: X-rays neutron stars elementary particles

Fabrication of multi-sectional TiO_2 nanotube arrays by anodization

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science china Chemistry 2010年第5期53卷 1067-1072页

作者： LI shiQi,YIN JianBo & ZHANG GengMin key laboratory for the physics and Chemistry of Nanodevices and Department of Electronics,{3.,beijing 100871,china 1. key laboratory for the physics and Chemistry of Nanodevices and Department of Electronics Peking University Beijing 100871 China

We report a facile method to grow multi-sectional TiO2 nanotube arrays consisting of alternating bamboo-shaped and smooth-walled nanotube sections by *** key factors are necessary for obtaining these ***,in order to avoid possible disruptions between the conjoint sections of the nanotube,the distribution of hydrogen ions is suggested not to be fiercely disturbed when switching from the first to the second ***,to avoid the disruption of the nanotube at the joint which results from the disparity in diameters between sections,the direct current voltage is set to be the maximum of the square wave *** newly developed TiO2 nanotube arrays are expected to have potential applications in solar cells,drug release and delivery systems.

关键词： titanium dioxide titania nanotube anodic oxidation

Modeling the intracellular dynamics for Vif-APO mediated HIV-1 virus infection

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Chinese science Bulletin 2010年第22期55卷 2329-2340页

作者： WANG Yi1,2 & LAI LuHua1,3.1 Center for Theoretical Biology, peking university, beijing 100871, china 2 school of {3., peking university, beijing 100871, china 3.BNLMs, state key laboratory for structural Chemistry of Unstable and stable species, College of Chemistry and Molecular Engineering, peking university, beijing 100871, china Center for Theoretical Biology Peking University Beijing 100871 China school of physics Peking University Beijing 100871 China BNLMs State Key Laboratory for Structural Chemistry of Unstable and Stable Species College of Chemistry and Molecular Engineering Peking University Beijing 100871 China

The viral infectivity factor (Vif) was found to be essential for controlling HIV-1 virus infectivity. It targets cellular antiviral proteins in APOBEC family (APO) to trigger its fast degradation and inhibits APO packaging into nascent virion. In the present study, we propose a mathematical model to quantitatively study the intracellular dynamics of these typical virus-host interactions. Four sets of published experimental data were compared with simulation results to justify the model. systematic parameter sensitivity and perturbation analysis showed that parameters related to APO are crucial to the infectivity of newly synthesized HIV-1 virus. Interestingly, we discovered that the synthesis rate of the viral structure protein Gag and the required number per nascent virion are optimized to achieve high virion production with minimal level of packaged APO, and large portion of model parameters are beneficial to virus only within a relatively small range. Furthermore, minor variations in several parameters related to viral protein Tat, the activator of viral RNA synthesis, were found to induce switch-like behaviors on both incorporated Vif and APO. These findings may provide new insights for understanding the high mutation rate of HIV-1 virus and its latency, as well as help identify key targets for therapeutic design.

关键词：病毒感染载脂蛋白 HIV 细胞内动力学抗病毒蛋白建模介导

Design of an MRI quadrature-data acquisition card

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Progress in Natural science:Materials International 2006年第3期16卷 255-259页

作者： JIANG Zhongde, ZU Donglin and GU Xiaofang (Institute of Heavy Ion physics, beijing key {3. of Medical physics & Engineering, school of physics, peking university,beijing 100871, china) [a]Institute of Heavy Ion physics Beijing Key Laboratory of Medical Physics & Engineering School of Physics Peking University Beijing China

A design of a quadrature-data acquisition card based on peripheral component interconnect (PCI) bus for mini-type magnetic resonance imaging (MRI) system is reported. It uses two high speed analog-to-digital converters (ADCs) to sample the MRI signals and two static random access memories (sRAMs) to store the data which will be read to the computer by PCI bus after sampling. All the logic control signals on the card are generated by the field programmable gate array (FPGA). The software Foundation3.1 is used to design the FPGA and achieve useful result after simulating and implementing. The card has some merits that normal commercial cards do not have. For example, the sampling parameters can be varied according to different pulse sequences.

关键词： MRI data acquisition FPGA PCI bus.

shape phase transitions in nuclei:Effective order parameters and trajectories

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science china(physics,Mechanics & Astronomy) 2011年第S1期54卷 88-97页

作者： ZHANG Yu1,2, HOU ZhanFeng2 & LIU YuXin2,3.1Department of physics, Liaoning Normal university, Dalian 116029, china 2Department of physics and the state key laboratory of nuclear physics and Technology, peking university, beijing 100871, china 3.enter of Theoretical nuclear physics, National laboratory of Heavy Ion Accelerator, Lanzhou 720000, china 1. Department of physics Liaoning Normal University Dalian 116029 China2. Department of Physics and the State Key Laboratory of Nuclear Physics and Technology Peking University Beijing 100871 China3. Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Accelerator Lanzhou 720000 China

We analyze systematically the effective order parameters in nuclear shape phase transition both in experiments and in the interacting boson model. We find that energy ratios and B(E2) ratios can distinguish the first from the second-order phase transition in theory above a certain boson number N (about 50), but in experiments, only those quantities, such as E(L1+)/E(02+) and B(E2; (L+2)1 → L1)/B(E2; 21 → 01), etc., of which the monotonous transitional behavior in the second-order phase transition is broken in the first order phase transition independent of N, are qualified as the effective order parameters. By implementing the originally proposed effective order parameters and the new ones, we find that the isotones with neutron number Nn = 62 are a trajectory of the second order phase transition. In addition, we predict that the transitional behavior of isomer shifts of Xe, Ba isotopes and Nn = 62 isotones is approximately monotonous due to the finiteness of nuclear system.

关键词： nuclear shape phase transition interacting boson model effective order parameter finite particle number effect transition trajectory