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

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, peking university, beijing 100871,{3. The Medical school of peking university, beijing 100083.{3. 3. The First Hospital of peking university, beijing 10003.,{3.) [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.

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Improved innovation-based adaptive Kalman filter for dual-frequency navigation using carrier phase

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science china(Information sciences) 2010年第12期53卷 2653-2663页

作者： LU ChenXi,TAN YunHua ,ZHU BoCheng & ZHOU LeZhu school of electronics engineering and Computer {3.,peking university,beijing 100871,china 1. school of electronics engineering and Computer {3. Peking University Beijing 100871 China

A new adaptive Kalman filtering algorithm for dual-frequency navigation using carrier phase is *** algorithm gives consideration to both robustness and sensitivity by combining the two main approaches of adaptive Kalman filtering based on innovation-based adaptive estimation(IAE) and fading *** to the navigation using carrier phase measurements typically,this algorithm can balance the weights of observations and predicted states *** to both practical static data and kinetic simulations are presented to demonstrate the validity and efficiency of the algorithm.

关键词： navigation adaptive Kalman filter carrier phase

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A malware detection model based on a negative selection algorithm with penalty factor

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science china(Information sciences) 2010年第12期53卷 2461-2471页

作者： ZHANG PengTao 1,2 , WANG Wei 1,2 & TAN Ying 1,2 1 Department of Machine Intelligence, school of electronics engineering and Computer {3., peking university, beijing 100871, china 2 Key Laboratory of Machine Perception, Ministry of Education, peking university, beijing 100871, china 1. Department of Machine Intelligence School of Electronics Engineering and Computer Science Peking University Beijing 100871 China2. Key Laboratory of Machine Perception Ministry of Education Peking University Beijing 100871 China

A malware detection model based on a negative selection algorithm with penalty factor (NSAPF) is proposed in this paper. This model extracts a malware instruction library (MIL), containing instructions that tend to appear in malware, through deep instruction analysis with respect to instruction frequency and file frequency. From the MIL, the proposed model creates a malware candidate signature library (MCSL) and a benign program malware-like signature library (BPMSL) by splitting programs orderly into various short bit strings. Depending on whether a signature matches "self", the NSAPF further divides the MCSL into two malware detection signature libraries (MDSL1 and MDSL2), and uses these as a two-dimensional reference for detecting suspicious programs. The model classifies suspicious programs as malware and benign programs by matching values of the suspicious programs with MDSL1 and MDSL2. Introduction of a penalty factor C in the negative selection algorithm enables this model to overcome the drawback of traditional negative selection algorithms in defining the harmfulness of "self" and "nonself", and focus on the harmfulness of the code, thus greatly improving the effectiveness of the model and also enabling the model to satisfy the different requirements of users in terms of true positive and false positive rates. Experimental results confirm that the proposed model achieves a better true positive rate on completely unknown malware and a better generalization ability while keeping a low false positive rate. The model can balance and adjust the true positive and false positive rates by adjusting the penalty factor C to achieve better performance.

关键词： penalty factor negative selection algorithm signature extraction artificial immune system mal- ware detection

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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 {3. of Physics, 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

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Towards a degradation-based mechanism for adaptive overload control

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science china(Information sciences) 2012年第12期55卷 2708-2722页

作者： WANG ZiYou 1,2,ZHOU MingHui 1,2 & MEI Hong 1,2 1 Software Institute,school of electronics engineering and Computer {3.,peking university,beijing 100871,china 2 Key Laboratory of High Confidence Software Technologies(peking university),Ministry of Education,beijing 100871,china 1. Software Institute School of Electronics Engineering and Computer Science Peking University Beijing 100871 China 2. Ministry of Education Key Laboratory of High Confidence Software Technologies (Peking University) Beijing 100871 China

Uncontrolled overload is one of the major causes of the system's decline in reliability and performance for web *** also harms the construction of trustworthy *** paper presents a degradationbased mechanism to adaptively control overload in complex,dynamic web *** our mechanism,the bottlenecks in the application's performance are determined by internally monitoring the performance and resource utilization state of the application,which is decomposed into a set of *** locating the bottlenecks,two decision algorithms are proposed to dynamically and adaptively generate proper degradation plans without *** degrading the service which consumes critical resources and has a low priority from the perspective of business logic,the application can keep providing key services even when overload *** implement a prototype and conduct a case study on a wiki *** also evaluate our approach and demonstrate its effectiveness in simulated overload *** handling overload,we make a breakthrough in building trustworthy software in an open,dynamic and rapidly changing environment.

关键词： overload service degradation resource monitoring performance management

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Technical framework for Internetware: An architecture centric approach

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science in china(Series F) 2008年第6期51卷 610-622页

作者： YANG FuQing1,2, Lü Jian3.4 & MEI Hong1,2 1 Key Laboratory of High Confidence Software Technologies (peking university), Ministry of Education, beijing 100871,{3. 2 school of electronics engineering and Computer science, peking university, beijing 100871,{3. 3.State Key Laboratory for Novel Software Technology, Nanjing 210093.{3. 4 Department of Computer science and Technology, Nanjing university, Nanjing 210093.{3. 1. Key Laboratory of High Confidence Software Technologies (peking university) Ministry of Education Beijing 100871 China 2. school of electronics engineering and Computer {3. Peking University Beijing 100871 China 3. State Key Laboratory for Novel Software Technology Nanjing 210093 China 4. Department of Computer science and Technology Nanjing University Nanjing 210093 China

Being a new software paradigm evolved by the Internet, Internetware brings many challenges to the traditional software methods and techniques. Sponsored by the national basic research program （973., researchers in china have developed an architecture centric technical framework for the definition, incarnation and engineering of Internetware. First of all, a software model for Internetware is defined for what to be, including that Internetware entities should be packaged as components, behaving as agents, interoperating as services, collaborating in a structured and on demand manner, etc. Secondly, a middleware for Internetware is designed and implemented for how to be, including that Internetware entities are incarnated by runtime containers, structured collaborations are enabled by runtime software architecture, Internetware can be managed in a reflective and autonomic manner, etc. Thirdly, an engineering methodology for Internetware is proposed for how to do, including the way to develop Internetware entities and their collaborations by transforming and refining a set of software architectures which cover all the phases of software lifecycle, the way to identify and organize the disordered software assets by domain modeling, etc.

关键词： Internetware component software architecture agent middleware

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PDMS prism-glass optical coupling for surface plasmon resonance sensors based on MEMS technology

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science china(Information sciences) 2010年第10期53卷 2144-2158页

作者： GENG ZhaoXin 1,2 , LI Qing 3., WANG Wei 1 & LI ZhiHong 1 1 Institute of Microelectronics, peking university, beijing 100871,{3. 2 school of Information engineering, Minzu university of{3., beijing 100081,{3. 3.school of sciences, Changchun university of science and Technology, Changchun 13.000,{3. 1. Institute of Microelectronics Peking University Beijing 100871 China2. School of Information engineering Minzu University of China Beijing 100081 China3. School of Sciences Changchun University of Science and Technology Changchun 130000 China

A miniaturized surface plasmon resonance (SPR) chip has been developed for biomedical and chem-ical analysis with low cost and high performance. The techniques of bulk silicon micromachining and polymer replication were used to fabricate the Kretschmann SPR sensor composed of a Polydimethylsiloxane (PDMS) prism, a coupling glass and microchannels. The plasmon properties of thin metal films were investigated theoret-ically based on Fresnel analysis, with optical boundary conditions pertaining to the surface plasmon resonance at the gold/water and gold/air interfaces. The theoretical results show that difference in the refractive index (RI) between the PDMS prism and the coupling glass layer affect the precision of the SPR angle and the SPR curve. Meanwhile, the period of the interference fringe attaching on the SPR curve increases with an increase in wavelength and a decrease in the refractive index of the coupling glass layer. The gold thickness of 50 nm is required while employing a fixed incident wavelength of 650 nm, to achieve optimum SPR excitation conditions and the sensor sensitivity. The characteristics of this SPR sensor were evaluated in the angular interrogation mode of employing the incident wavelength of 650 nm in air and water media, respectively. The obtained SPR angles were approximately consistent with the theoretical ones.

关键词： surface plasmon resolance polymer microfluidic PDMS

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A community-centric approach to automated service composition

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science china(Information sciences) 2010年第1期53卷 50-63页

作者： LIU XuanZhe1,2, HUANG Gang1,2 & MEI Hong1,2 1school of electronics engineering and Computer {3., peking university, beijing 100871, china 2Key Laboratory of High Confidence Software Technologies, Ministry of Education, peking university, beijing 100871, china 1. school of electronics engineering and Computer {3. Peking University Beijing 100871 China2. Key Laboratory of High Confidence Software Technologies Ministry of Education Peking University Beijing 100871 China

In the recent years, the web has kept growing rapidly and undergone tremendous changes towards a user-centric environment. With the proliferation of services available on the Internet, millions of users are able to voluntarily participate in and collaborate for their own interests and benefits by means of service composition. However, due to the ever increasing number of services, it then becomes a challenging issue to enable the users to rapidly select and compose the proper services. In this paper, we propose an approach which utilizes service communities for automated service composition. This paper makes three contributions. Firstly, we propose the service community architecture and identify two key components to facilitate service discovery and composition. Secondly, assisted by the service community, we provide two composition types to help users explore the space of potential composition opportunities without having to understand too many details of individual candidate services. Finally, we evaluate our approach by performance analysis and provide a web-based prototype that lowers the entry barrier for the users.

关键词： services computing service composition service community

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Singularity detection of the rabbit electrocardiogram:An evolutionary spectral method

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Progress in Natural science:Materials International 2009年第10期19卷 1317-1326页

作者： Xinyuan Liua,Dingwu He a,Liuqing Pei b,Suming Zhanga a school of electronics engineering and Computer {3.,peking university,beijing 100871,china b College of Information {3. and engineering,beijing Normal university,beijing 100875,china [a]school of electronics engineering and Computer {3. Peking University Beijing 100871 China [b]College of Information science and engineering Beijing Normal University Beijing 100875 China

The time-frequency characteristics of the spectral density of non-stationary signals(NSS) in the neighborhood of an instant time point can be determined using the evolutionary spectral *** experimental rabbit model involving ligation of the left anterior descending coronary artery to simulate the physiology of early phase myocardial ischemia(EPMI) has been previously ***,EPMI derived from left coronary artery stenosis is the main symptom of coronary heart diseases including acute myocardial ***,we propose a new algorithm for estimating the evolutionary spectral density functions,which is an effective approach to determine the instantaneous frequency spectra(IFS) of NSS under the uncertainty principle in the time-frequency *** localization singularity information in the data recorded from a living system could be detected by means of the ***(ECG) data recorded from experimental rabbits were analyzed with the new *** showed that the Q’s value of the evolutionary spectral quality number of the QRS-complex data was the characteristic parameter of ECG,and there was a matched connection between the time-frequency characteristics of QRS-complex data and the myocardial ischemia symptoms of the *** results provide valuable information regarding features of the EPMI for use in clinical diagnoses.

关键词： Non-stationary signals Electrocardiogram(ECG) Evolutionary spectrum Instantaneous frequency spectrum(IFS) Myocardial ischemia

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Analysis for twinning and slip in face-centered cubic crystals under axisymmetric co-deformation

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science china(Technological sciences) 2006年第5期49卷 521-536页

作者： CHEN Zhiyong1,2, CAI Hongnian1, ZHANG Xinming2, WANG Fuchi1 & TAN Chengwen1,3.1. school of Material science and engineering, {3. Institute of Technology, {3. 100081, china 2. school of Material science and engineering, Central South university, Changsha 410083. china 3. school of Material science and engineering, {3. university of Aeronautics and Astronautics, {3. 100083. china 1. school of Material science and engineering Beijing Institute of Technology Beijing 100081 China 2. school of Material science and engineering Central South University Changsha 410083 China 3. school of Material science and engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

The maximum work principle of Bishop-Hill was developed to analyze the axisymmetric co-deformation in face-centered cubic crystals (f.c.c.) for twinning on {111} 112 and slip on {111} 110 systems. The influence of ξ , the ratio of critical re- solved shear stress for twinning to slip, on the yield stress states and corresponding active slip or/and twinning systems for orientations in the standard stereographic triangle of cubic crystal was investigated systematically. The Taylor factors and the anisotropy of yield strength for three important orientations [100], [110] and [111] in orientation space were analyzed. It is found that the yield strength asymmetry for the case of axisymmetric de- formation of tension and compression can be explained based on the microscopic theory of crystal plasticity. The concept of orientation factor for twinning ability was proposed and the deformation mechanism map in the orientation space was established for the case of axisymmetric deformation. The deformation texture formation and development of f.c.c. crystals with low stacking fault energy for axisymmetric tension can be explained qualita- tively on the basis of analyzed results.

关键词： twinning slip face-centered cubic crystals axisymmetric co-deformation Bishop-Hill maximum work principle yield strength anisotropy

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