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Structural Basis for the Thermostability of Sulfur Oxygenase Reductases

Chinese Journal of Chemical Engineering 2012年第1期20卷 52-61页

作者：尤晓颜孟珍陈栋炜郭旭 Josef Zeyer 刘双江姜成英 State Key Laboratory of Microbial Resources Institute of MicrobiologyChinese Academy of Sciences Scientific Data Center Computer Network Information CenterChinese Academy of Sciences Environmental Microbiology Institute for Biogeochemistry and Pollutant Dynamics(IBP)Federal Institute of Technology(ETH)Switzerland

The thermostability of three sulfur oxygenase reductases （SORs） was investigated from thermoacidophilic achaea Acidianus tengchongensis （SORAT） and Sulfolobus tokodaii （SORsT） as well as the moderately thermophilic bacterium Acidithiobacillus sp. SM-1 （SORsB）. The optimal temperatures for catalyzing sulfur oxidation were 80 ℃ （SORAT）, 85 ℃ （SORsT）, and 70 ℃ （SORsB）, respectively. The half-lives of the three SORs at their optimal catalytic conditions were 100 min （SORAT）, 58 min （SORsT）, and 37 min （SORsB）. In order to reveal the structural basis of the thermostability of these SORs, three-dimensional structural models of them were generated by homology modeling using the previously reported high-resolution X-ray structure of SORAA （from Acidianus ambivalens） as a template. The results suggest that thermostability was dependent on：（a） high number of the charged amino acid glutamic acid and the flexible amino acid proline, （b） low number of the therraolabile amino acid glutamine, （c） increased number of ion pairs, （d） decreased ratio of hydrophobie accessible solvent surface area （ASA） to charged ASA, and （e） increased volumes of the cavity. The number of cavities and the number of hydrogen bonds did not signifieantly affect the thermostability of SORs, whereas the cavity volumes increased as the thermal stability increased.

关键词： sulfur oxygenase reductase （SOR） thermostability homology modeling Acidianus Sulfolobus Acid- ithiobacillus

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Microblog bursty feature detection based on dynamics model

Microblog bursty feature detection based on dynamics model

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International Conference on Systems and Informatics (ICSAI)

作者： Yanyan Du Wei Wu Yanxiang He Nan Liu School of Computer Wuhan University of China Wuhan China Key Laboratory of Information Network Security Ministry of Public Security Shanghai China

Microblog is becoming more and more popular in our life. Due to the numerous information on this platform, it is very useful to detect bursty topic in real-time to help people get essential information quickly. As a necessary stage, detecting busty feature effectively is important for bursty topic detection. Based on dynamics model, we propose a new microblog bursty feature detection method. Firstly, we compute term weight taking account of both term frequency and tweet weight, where tweet weight factors include retweet number, comments number and time fading factor. After computing all terms' weight, a bursty feature detection method is proposed based on dynamics model. On the analogy of physical dynamics model, we compute each term's momentum by using MACD (Moving Average Convergence/Divergence) and determine whether it is a bursty feature in a given time interval. We employ our method to detect the bursty terms of Sina tweets with a series of experiments. It is demonstrated that our method is able to detect bursts for news terms accurately and efficiently.

关键词： Feature extraction Hidden Markov models Data mining Computational modeling Accuracy Security Analytical models

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Generalized geometry-based optimal power control in wireless networks

Generalized geometry-based optimal power control in wireless...

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2012 9th Annual IEEE Communications Society Conference on Sensor, Mesh and Ad Hoc Communications and networks, SECON 2012

作者： Wang, Wei Shin, Kang G. Zhang, Zhaoyang Wang, Wenbo Peng, Tao Department of Information Science and Electronic Engineering Zhejiang Provincial Key Laboratory of Information Network Technology Zhejiang University Hangzhou 310027 China Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI 48109-2121 United States Wireless Signal Processing and Networking Lab Beijing University of Posts and Telecommunications Beijing 100876 China

ISBN: (纸本)9781467319058

Geometry-based optimal power control was proposed in [14] to transform the power-control problem to a new geometrical problem on the position relationship between a line and some points. This scheme provides a novel visual perspective and lowers the complexity of optimization. We generalize this scheme to a larger class of power-control optimization problems so as to maximize the network utility with multiple average and peak power constraints in wireless networks. To facilitate the handling of the geometrical model, we define a subset of geometrical models with specified characteristics, called a regular geometrical model, and derive the type of power-control problems eligible for the regular geometrical model. For such a type of problems, two strategies are proposed for the construction of the regular geometrical model. Utilizing geometrical properties, we propose a novel geometry-based optimization scheme for the general power-control problem. Its computational complexity is significantly lower than the conventional algorithms. We also provide a further discussion on irregular geometrical model cases. Finally, we provide two examples of deploying the proposed geometry-based power-control scheme. © 2012 IEEE.

关键词： Geometry

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Path planning of mobile anchor in three-dimensional wireless sensor networks for localization

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Journal of information and Computational Science 2012年第8期9卷 2203-2210页

作者： Cui, Huanqing Wang, Yinglong Lv, Jialiang College of Information Science and Engineering Shandong University of Science and Technology Qingdao 266590 China Shandong Provincial Key Laboratory of Computer Network Shandong Computer Science Center Ji'nan 250014 China

Node-localization is one of the key technologies of wireless sensor networks, and mobile-anchor assisted localization method is a promising method of saving network cost. The path planning of mobile anchor is a basis of this method. For the wireless sensor networks deployed in 3-dimensional space, five deterministic paths named by Layered-Scan, Layered-Curve, Triple-Scan, Triple-Curve and 3D-Hilbert are proposed that can cover a given cubic region of interest entirely. Taken weighted centroid localization method as example, detailed simulations are performed with difference parameters. The results show that all of these five paths are better than random moving path, and 3D-Hilbert is the best path with shortest length and minimal average localization error. © 2012 Binary information Press.

关键词： Motion planning

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Analysis of modular inverse and improvement of extended euclid algorithm

International Journal of Digital Content Technology and its ...

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International Journal of Digital Content Technology and its Applications 2012年第7期6卷 225-233页

作者： Xin, Li Ru, Zhang Xinxin, Niu Junfeng, Xu Information Security Center Beijing University of Posts and Telecommunications China Information Security Center Beijing University of Posts and Telecommunications Key Laboratory of Information Network Security Ministry of Public Security China National Computer network Emergency Response technical Team/Coordination Center of China China

The properties of modular inverse were analyzed and gain to improve the extended Euclid algorithm. In the new scheme, even-reduction and remainder-attenuation were proposed which insured the remainder be attenuated to one third of before in each loop at least, so that for y = a-1 mod p, the number of loops will be lower than log 3 a. Software testing shows the new algorithm is significantly improved on speed than the original algorithm.

关键词： Software testing

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Security Analysis of an Electronic Commerce Protocol Using Casper/FDR2

Security Analysis of an Electronic Commerce Protocol Using C...

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第六届中国可信计算与信息安全学术会议

作者： CHANG Yinlong HU Huaping Department of Mathematics and Computer Science/Key Laboratory of Information Security of Network Sys School of Computer Science National University of Defense TechnologyChangsha 410073HunanChina

Researchers have proposed several security protocols to protect the electronic commerce security in these years;however,not all of them are secure *** article extends model checking method with Casper/FDR2 to model and analyze a new electronic *** are found in the protocol and their mechanisms are discussed.A variety of solutions are given to different security *** improved protocol is proven to be robust and secure.

关键词： Casper FDR2 electronic commerce model checking formal analysis

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Provably secure and effcient identity-based signature scheme based on cubic residues

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International Journal of network Security 2012年第1期14卷 33-38页

作者： Wang, Zhiwei Wang, Licheng Zheng, Shihui Yang, Yixian Hu, Zhengming Key Laboratory of Network and Information Attack and Defence Technology of MOE Beijing University of Posts and Telecommunications Beijing 100876 China College of Computer Nanjing University of Posts and Telecommunications China

Many identity based signature (IBS) schemes have been proposed so far. However, most of the schemes are based on bilinear pairings. Only a few IBS schemes are with-out pairings. Up to now, there still remains a challenge to construct a provably secure and effcient IBS scheme without pairings. In this paper, we propose an effcient IBS scheme based on cubic residues, and we prove that our scheme is secure against adaptively chosen message and ID attack.

关键词： Public key cryptography

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Performance analysis of vector OFDM with linear MMSE receiver

Performance analysis of vector OFDM with linear MMSE receive...

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2012 1st IEEE International Conference on Communications in China, ICCC 2012

作者： Li, Yabo Ngebani, Ibo Xia, Xiang-Gen Høst-Madsen, Anders Department of Information Science and Electrical Engineering Zhejiang Provincial Key Laboratory of Information Network Technology Zhejiang University Hangzhou Zhejiang China Department of Electrical and Computer Engineering University of Delaware Newark DE 19716 United States Department of Electrical Engineering University of Hawaii at Manoa Honolulu HI 96822 United States Chonbuk National University Jeonju Korea Republic of

ISBN: (纸本)9781467328159

Vector OFDM (V-OFDM) for single transmit antenna systems is a general transmission scheme in which OFDM and Single-Carrier Frequency Domain Equalization (SC-FDE) can be considered as two extreme/special cases. Due to its flexibility, it has attracted more and more attention recently. So far all studies about V-OFDM assume the Maximum Likelihood (ML) receiver. In this paper, we investigate the performance of V-OFDM with linear Minimum Mean Square Error (MMSE) receiver. We first show that for linear MMSE receiver, all the vector blocks (VB) in V-OFDM have equal performance, this is different from V-OFDM with ML receiver, where different VBs may have different performances. Then, we analyze the diversity order of V-OFDM with linear MMSE receiver, and show that, regardless of the V-OFDM symbol length N, the diversity order can be represented as min{[M2-R], D} + 1, where M is the VB size, /i is the spectrum efficiency in bits/symbol, and D is the maximum delay of the multipath channel. © 2012 IEEE.

关键词： Orthogonal frequency division multiplexing

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A generic approach for providing revocation support in secret handshake

A generic approach for providing revocation support in secre...

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14th International Conference on information and Communications Security, ICICS 2012

作者： Yang, Yanjiang Lu, Haibing Weng, Jian Ding, Xuhua Zhou, Jianying Institute for Infocomm Research Singapore Singapore Dept. of Operations Management and Information Systems Leavey School of Business Santa Clara University United States Department of Computer Science Emergency Technology Research Center of Risk Evaluation and Prewarning on Public Network Security Jinan University China Shanghai Key Laboratory of Integrate Administration Technologies for Information Security Shanghai China School of Information Systems Singapore Management University Singapore Singapore

ISBN: (纸本)9783642341281

Privacy protection and user revocation are essentially conflicting requirements in many cryptographic protocols. It is a particularly challenging problem to harmonize them in a secret handshake protocol that is geared to offering strong privacy protection on the participants' group membership in the protocol execution. In this paper, we study this problem and propose a generic approach to provide revocation support in secret handshake protocols, without sacrificing the notion of privacy preserving. The main building block of our approach is CGC (Confidential Group Communication), a primitive formulated in this paper, and we present a concrete instantiation so as to realize our generic approach. © 2012 Springer-Verlag.

关键词： Data privacy

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DRTEMBB: Dynamic recommendation trust evaluation model based on bidding

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Journal of Multimedia 2012年第4期7卷 279-288页

作者： Wang, Gang Gui, Xiao-lin Department of Electronics and Information Engineering Xi'an Jiaotong University Xi'an China Shanxi Province Key Laboratory of Computer Network Xi'an Jiaotong University Xi'an China School of Information Xi'an University of Finance and Economics Xi'an China

Fraud or cheating of malicious nodes were restrained by reducing the trust value of malicious nodes in the past trust model, but few recommendation nodes for cooperation cheating are punished, so it has had only limited malicious recommendation or fraudulent action again and again. Due to lack of punishment for malicious recommendation of recommendation nodes, enormous malicious recommendation nodes remain and search for next criminal opportunity. By borrowing idea of bidding and the introduction of competition and the mechanism of rewards and penalty, this paper proposes a dynamic recommendation trust evaluated model based on bidding in E-Commerce environment. By greatly increasing the "criminal cost" of malicious recommendation nodes, with recommendation optimization algorithm based on Markov chain, the model ensures that the recommendation service is true and more objective, which will stimulate the enthusiasm of nodes objective recommendation and reach the goal that nodes give up malicious recommendation and cooperative cheating on its own initiative by objective method so as to restrain malicious recommendation and cooperative cheating effectively. In simulation experiment, the model also shows good restraint on malicious recommendation. © 2012 ACADEMY PUBLISHER.

关键词： Crime

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