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A puzzle of the radio-quiet quasar PG 1407+265:Are optical and X-ray emissions produced from a relativistic jet?

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Science China(Physics,Mechanics & Astronomy) 2011年第1期54卷 183-186页

作者： CHEN Liang 1,2,3.& BAI JinMing 1,2 1 National Astronomical Observatories/Yunnan Observatory,chinese academy of sciences,Kunming 650011,China 2 Key Laboratory for the Structure and Evolution of Celestial Objects,chinese academy of sciences,Kunming 650011,China 3.graduate university of chinese academy of sciences,beijing 100049,China 1. National Astronomical Observatories/Yunnan Observatory Chinese Academy of Sciences Kunming 650011 China2. Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China3. Graduate University of Chinese Academy of Sciences Beijing 100049 China

PG 1407+265 is a radio quiet quasar that has a relativistic *** this report,we show some peculiar properties of its optical and X-ray emissions,which indicate possible non-thermal origins produced from the *** use a simple synchrotron + synchrotron self Compton (SSC) model to fit the emissions with different ratios of energy densities between the magnetic field and electrons (η≡U B/U e),which predicts a different γ-ray *** First LAT AGN Catalog (1LAC) did not include PG 1407+265,which indicates an upper limit of γ-ray *** upper limit constrains the ratio to be unreasonably large (η≥10 4-5).This inversely indicates that the optical and X-ray emissions may not be produced from the beaming *** discuss the physical implications of these results.

关键词： active galactic nuclei jet non-thermal emission PG 1407+265

Valuations on arithmetic surfaces

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Science China Mathematics 2009年第1期52卷 66-76页

作者： XU Ning Department of Mathematics, graduate School of chinese academy of {3., beijing 100049, China Department of Mathematics Graduate School of Chinese Academy of Sciences Beijing 100049 China

In this paper, we give the definition of the height of a valuation and the definition of the big field ? p,G , where p is a prime and G ? ? is an additive subgroup containing 1. We conclude that ? p,G is a field and ? p,G is algebraically closed. Based on this the author obtains the complete classification of valuations on arithmetic surfaces. Furthermore, for any m ? p,G n ∈ ?, let V m,n be an ∝-vector space of dimension n - m + 1, whose coordinates are indexed from m to n. We generalize the definition of ? p,G , where p is a prime and G ? V m,n is an additive subgroup containing 1. We also conclude that ? p,G is a field if m ? 0 ? n.

关键词： valuation height rank totally ordered group big field transcendental number 14J10

CMQV+:An authenticated key exchange protocol from CMQV

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Science China(Information sciences) 2012年第7期55卷 1666-1674页

作者： LI Hui 1,2 & WU ChuanKun 1 1 State Key Laboratory of Information Security,Institute of Software,chinese academy of sciences,{3. 100190,China 2 graduate university of chinese academy of sciences,{3. 100049,China 1. State Key Laboratory of Information Security Institute of Software Chinese Academy of Sciences Beijing 100190 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China

Ustaoglu presents a secure and efficient key exchange protocol named CMQV,based on the design rationales of HMQV and *** with the latter two protocols,on one hand,CMQV achieves high performance of HMQV,and on the other,it is proven secure in eCK model as NAXOS ***,CMQV enjoys the security proof under gap Diffie-Hellman assumption as indicated by its *** this paper,we propose a variant of CMQV,called CMQV+,which is proven secure under a weaker assumption (*** Diffie-Hellman assumption) in eCK model with random oracles while maintaining the high-performance feature of CMQV as much as possible.

关键词： key exchange eCK model trapdoor-test technique provable security CDH assumption

An ID-based authenticated dynamic group key agreement with optimal round

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Science China(Information sciences) 2012年第11期55卷 2542-2554页

作者： TENG JiKai1,2,WU ChuanKun1 & TANG ChunMing3.1State Key Laboratory of Information Security,Institute of Software of chinese academy of sciences,{3. 100090,China 2graduate university of chinese academy of sciences,{3. 100049,China 3.aculty of Mathematic and Information Science,Guangzhou university,Guangzhou 510006,China 1. State Key Laboratory of Information Security Institute of Software of Chinese Academy of Sciences Beijing 100090 China 2. graduate university of chinese {3. of sciences Beijing 100049 China 3. Faculty of Mathematic and Information Science Guangzhou University Guangzhou 510006 China

Group key agreement protocols are crucial for achieving secure group *** are designed to provide a set of users with a shared secret key to achieve cryptographic goal over a public *** group membership changes,the session key should be refreshed efficiently and *** previous group key agreement protocols need at least two rounds to establish or refresh session *** this paper,a dynamic authenticated group key agreement(DAGKA) protocol based on identity-based cryptography is *** making use of the members' values stored in previous sessions,our Join and Leave algorithms reduce the computation and communication costs of *** the proposed protocol,Setup and Join algorithms need one *** session key can be refreshed without message exchange among remaining users in Leave algorithm,which makes the protocol more *** security is proved under decisional bilinear Diffie-Hellman(DBDH) assumption in random oracle model.

关键词： identity-based cryptography dynamic group key agreement provably secure admissible pairing

A two-round honest-verifier zero-knowledge protocol

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Science China(Information sciences) 2010年第5期53卷 954-963页

作者： LIU HanWu 1,2 & LIN DongDai 1 1 The State Key Laboratory of Information Security, Institute of Software, chinese academy of sciences, {3. 100190, China 2 graduate university of the chinese academy of sciences, beijing 100049, China 1. The State Key Laboratory of Information Security Institute of Software Chinese Academy of Sciences Beijing 100190 China2. Graduate University of the Chinese Academy of Sciences Beijing 100049 China

Since the concept of zero-knowledge protocols was introduced, it has attracted a lot of attention and in turn showed significant effect on the development of cryptography, complexity theory and other areas. The round complexity of a zero-knowledge protocol is a very important efficiency consideration, and it is required to be as small as possible. Generally, it is desirable to have zero-knowledge protocols with constant numbers of rounds. Goldreich and Oren proved that only languages in BPP have one-round and two-round zero-knowledge protocols. Moreover, they also showed that only languages in BPP have one-round honest-verifier zero-knowledge protocols. The notion of honest-verifier zero-knowledge protocols is highly non-trivial and fascinating itself, and has many other uses. Thus, the problem as to whether there exist two-round honest-verifier zero-knowledge protocols becomes an important open problem. In this paper, we introduce a new simulation technique and present a two-round honest-verifier zero-knowledge protocol for any language in N P under a standard complexity assumption based on this technique.

关键词： proof system argument system zero-knowledge witness indistinguishability black-box one-way permutation commitment scheme zap

Genesis of ^(23.)Th excess in basalts from mid-ocean ridges and ocean islands:Constraints from the global U-series isotope database and major and rare earth element geochemistry

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Science China Earth sciences 2010年第10期53卷 1486-1494页

作者： ZHANG GuoLiang1,2 & ZENG ZhiGang1 1 Key Laboratory of Marine Geology and Environment,Institute of Oceanology,chinese academy of sciences,Qingdao 266071,China 2 {3. university of chinese academy of sciences,beijing 100049,China 1. Key Laboratory of Marine Geology and Environment Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China

Based on 23.Th-23.U disequilibrium and major element data from mid-ocean ridge basalts(MORBs) and ocean island basalts(OIBs),this study calculates mantle melting parameters,and thereby investigates the origin of 23.Th excess.(23.Th/23.U) in global MORBs shows a positive correlation with Fe8,Po,Na8,and Fmelt(Fe8 and Na8 are FeO and Na2O contents respectively after correction for crustal fractionation relative to MgO = 8 wt%,Po=pressure of initial melting and Fmelt=degree of melt),while 23.Th excess in OIBs has no obvious correlation with either initial mantle melting depth or the average degree of mantle ***,compared with the MORBs,higher(23.Th/23.U) in OIBs actually corresponds to a lower melting *** suggests that the 23.Th excess in MORBs is controlled by mantle melting conditions,while the 23.Th excess in OIBs is more likely related to the deep garnet *** vast majority of calculated initial melting pressures of MORBs with excess 23.Th are between 1.0 and 2.5 GPa,which is consistent with the conclusion from experiments in recent years that DU>DTh for Al-clinopyroxene at pressures of >1.0 *** initial melting pressure of OIBs is 2.2-3.5 GPa(around the spinel-garnet transition zone),with their low excess 226Ra compared to MORBs also suggesting a deeper mantle ***,excess 23.Th in MORBs and OIBs may be formed respectively in the spinel and garnet stability *** addition,there is no obvious correlation of K2O/TiO2 with(23.Th/23.U) and initial melting pressure(Po) of MORBs,so it is proposed that the melting depth producing excess 23.Th does not tap the spinel-garnet transition *** and MORBs in both(23.Th/23.U) vs.K2O/TiO2 and(23.Th/23.U) *** plots fall in two distinct areas,indicating that the mineral phases which dominate their excess 23.Th are ***/Yb-Ce curves of fast and slow ridge MORBs are similar,while,in comparison,the Ce/Yb-Ce curve for OIBs shows more influence from *** mechanism

关键词： excess 23.Th clinopyroxene garnet spinel-lherzolite mid-ocean ridge ocean island

Review on the study of entanglement in quantum computation speedup

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chinese Science Bulletin 2007年第16期52卷 2161-2166页

作者： DING ShengChao1,3.& JIN Zhi1,2,1 Institute of Computing Technology,chinese academy of sciences,{3. 100080,China 2 academy of Mathematics and Systems Science,chinese academy of sciences,{3. 100080,China 3.graduate university of chinese academy of sciences,{3. 100080,China Institute of Computing Technology Chinese Academy of Sciences Beijing 100080 China

The role the quantum entanglement plays in quantum computation speedup has been widely disputed. Some believe that quantum computation's speedup over classical computation is impossible if entan-glement is absent,while others claim that the presence of entanglement is not a necessary condition for some quantum algorithms. This paper discusses this problem systematically. Simulating quantum computation with classical resources is analyzed and entanglement in known algorithms is reviewed. It is concluded that the presence of entanglement is a necessary but not sufficient condition in the pure state or pseudo-pure state quantum computation speedup. The case with the mixed state remains open. Further work on quantum computation will benefit from the presented results.

关键词：量子论量子纠缠量子计算加速模拟

Improving the accuracy of image-based forest fire recognition and spatial positioning

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Science China(Technological sciences) 2010年第S1期53卷 184-190页

作者： JIANG LiLi 1,QI QingWen 1,ZHANG An 1,GUO ChaoHui 2 & CHENG Xi 1,3.1 Institute of Geographical sciences and Natural Resources Research,chinese academy of sciences,beijing 100101,China 2 China Center for Resources Satellite Data and Applications,beijing 100094,China 3.6} university of chinese academy of sciences,beijing 100049,China chinese Acad Sci Inst Geog Sci & Nat Resources Res Beijing 100101 Peoples R China China Ctr Resources Satellite Data & Applicat Beijing 100094 Peoples R China chinese Acad Sci Grad Univ Beijing 100049 Peoples R China

Forest fires are frequent natural *** is necessary to explore advanced means to monitor,recognize and locate forest fires so as to establish a scientific system for the early detection,real-time positioning and quick fighting of forest *** paper mainly expounds methods and algorithms for improving accuracy and removing uncertainty in image-based forest fire recognition and spatial ***,we discuss a method of forest fire recognition in visible-light *** are four aspects to improve accuracy and remove uncertainty in fire recognition:(1)eliminating factors of interference such as road and sky with high brightness,red leaves,other colored objects and objects that are lit up at night,(2)excluding imaging for specific periods and azimuth angles for which interference phenomena repeatedly occur,(3.improving the thresholding method for determining the flame border in image processing by adjusting the threshold to the season,weather and region,and (4)integrating the visible-light image method with infrared image ***,we examine infrared-image-based methods and approaches of improving the accuracy of forest fire recognition by combining the spectrum threshold with an object feature value such as the normalized difference vegetation index and excluding factors of disturbance such as interference signals,extreme weather and high-temperature ***,a method of visible analysis to enhance the accuracy of forest fire positioning is examined and realized;the method includes decreasing the visual angle,selecting central points,selecting the largest spots,and judging the selection of fire spots according to the central *** studies are examined and the results are found to be satisfactory.

关键词： forest fire monitoring spatial positioning accuracy improvement

Pollen limitation and variation in floral longevity in gynodioecious Potentilla tanacetifolia

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Journal of Systematics and Evolution 2011年第6期49卷 539-545页

作者： 1,2Hong YAO 1Yi-Bo LUO 1(State Key Laboratory of Systematic and Evolutionary Botany,Institute of Botany,chinese academy of sciences,{3. 100093.China) 2(graduate university of the chinese academy of sciences,{3. 100049,China) (State Key Laboratory of Systematic and Evolutionary Botany Institute of Botany Chinese Academy of Sciences Beijing 100093 China) (graduate university of the chinese {3. of sciences Beijing 100049 China) *Correspondence: Yi-Bo LUO *Correspondence: E-mail: luoyb@*** Tel.: 86-10-6283.514 Fax: 86-10-62590843.

Pollination limitation is common in flowering plants and is thought to be a factor driving the evolution of floral *** plasticity of floral longevity to pollination may be an adaptation of plants to pollen ***,this adaptation is less critical in short-lived *** evaluate pollen limitation and the plasticity of floral longevity to pollination in Potentilla tanacetifolia,a gynodioecious herb with short-lived flowers,we analyzed its breeding system,tested sex-differential pollen limitation,and compared variations in floral display size in natural populations in Duolun County,Inner Mongolia,*** pollination experiments and pollinator exclusion treatments revealed that *** is self-compatible and non-autonomously apomictic and shows sex-differential pollen *** plasticity of floral longevity to pollination was observed;the floral duration of female plants was prolonged by approximately 3.4 hours with pollination exclusion ***,the percentage of flowers displayed on female plants during pollination exclusion treatment was significantly higher than that during natural *** natural pollination conditions,the percentage of flowers displayed on female plants was significantly higher than on hermaphrodite ***,approximately 50%of the pollen grains spread out of the anthers of hermaphrodite flowers within 2 h of anthesis;the number of pollen grains adhering to the stigmas of hermaphrodite flowers was significantly higher than that adhering to female flowers when flowers shed their *** results indicate that variation in floral longevity may be an adaptive strategy to pollination conditions for gynodioecious ***.

关键词： floral longevity gynodioecy plasticity pollen limitation Potentilla tanacetifolia.