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Finite Groups in Which Sylow Normalizers Admit Supplements

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Acta Mathematica Sinica,English Series 2007年第3期23卷 417-422页

作者： Tian Ze li School of mathematical sciences,peking university,beijing 100871,P.R.china School of mathematical sciences Peking University Beijing 100871 P. R.China

For a group G and a subgroup M of G,we say that a subgroup A of G is a supplement toM in G,if G=*** prove that a finite group in which every Sylow normalizer admits a nilpotentsupplement is *** particular we confirm a... 详细信息

关键词： Sylow normalizer Supplement Wreath product

On the boundary value problem for harmonic maps of the Poincaré disc

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Chinese Science Bulletin 1997年第24期42卷 2025-2045页

作者： li ZhongDepartment of Mathematics, peking university, beijing 100871, china Department of Mathematics Peking University Beijing China

The boundary value problem for harmonic maps of the Poincare disc is discussed. The emphasis is on the non-smoothness of the given boundary values in the problem. Let T . be a subspace of the universal Teichmüller space, defined as a set of normalized quasisymmetric homeomorphisms h of the unit circle S onto itself where h admits a quasiconformal extension to the unit disc D with a complex dilatation μ satisfyingwhere ρ(z)|dz|2 is the Poincare metric of D. Let B . be a Banach space consisting of holomorphic quadratic differentials φ in D with normsIt is shown that for any given quasisymmetric homeomorphism h : S1→S1∈ T . , there is a unique quasiconformal harmonic map of D with respect to the Poincare metric whose boundary corresponding is h and the Hopf differential of such a harmonic map belongs to B .

关键词： Harmonic maps quasiconfomial mappings universal Teichmüller spaces.

Biotic communities of the marine ecosystem in Meizhou Bay

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Journal of Environmental sciences 1996年第1期8卷 48-56页

作者： Ren Jiuchang Cai Xiaoming (Center of Environmental sciences,peking university, beijing 100871,china)Chen Bin(College of life sciences, peking university, beijing 100871, china )li Peng(College of Chemistry and Molecular Engineering, peking university, Bei china

The current situation of biotic communities in Meizhou Bay is presented in this *** species composition,seasonal variation,and distribution of phytoplankton,zooplankton, red tide organisms,fishes,and benthos in Meizhou Bay were investigated,and the content of chlorophyll a and primary production and their seasonal variation were also *** water quality of Meizhou Bay was monitored by measuring the density of Escherichia coli. Results reveal that there is a great variety of species in Meizhou Bay and the water in Meizhou Bay is *** the individual numbers of various organisms are very low, especially those of ***,there are more than 40 species of red tide organisms and there exist opportunities of red tides between May and *** these demand cautious be taken in the future development of this area although it has great environment capacity.

关键词： biotic community marine ecosystem Meizhou Bay.

Monotone projected gradient methods for large-scale box-constrained quadratic programming

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Science china Mathematics 2006年第5期49卷 688-702页

作者： ZHOU Bin, GAO li & DAI Yuhong School of mathematical sciences and LMAM, peking university, beijing 100871, china State Key Laboratory of Scientific and Engineering Computing, Institute of Computational Mathematics and Scientific/Engineering Computing, Academy of Mathematics and Systems Science, Chinese Academy of sciences, beijing 100080, china School of mathematical sciences LMAM Peking University Beijing 100871 China State Key Laboratory of Scientific Engineering Computing Institute of Computational Mathematics Scientific/Engineering Computing Academy of Mathematics Systems Science Chinese Academy of Sciences Beijing 100080 China

Inspired by the success of the projected Barzilai-Borwein (PBB) method for largescale box-constrained quadratic programming, we propose and analyze the monotone projected gradient methods in this paper. We show by experiments and analyses that for the new methods,it is generally a bad option to compute steplengths based on the negative gradients. Thus in our algorithms, some continuous or discontinuous projected gradients are used instead to compute the steplengths. Numerical experiments on a wide variety of test problems are presented, indicating that the new methods usually outperform the PBB method.

关键词： projected gradients, monotone gradient methods, box-constrained quadratic programming, large-scale problems.

Analysis　of　relationship　between　economic　growth　and　environment　in　Benxi　Shiqiaozi　Development　Zone

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Journal of Environmental sciences 1996年第3期8卷 269-274页

作者： li Bin Ru Jiang Ye Wenhu Xu Yunlin(Center for Environmental sciences, peking university, beijing 100871,china) Center for Environmental sciences Peking University Beijing 100871 China

How to express and assess the coordination between environmental system and economic system is one crucial problem for the studies on regional sustainable *** present study applies environmental supporting capacity (ESC) to evaluate the comparative coordination of economic development plans in a case study in Shiqiaozi Development *** analysis conclusion showed the method is practicable.A new method for judging the efficiency of utilization of environmental system is also discussed in this paper.

关键词： sustainable development coordination environmental supporting capacity(ESC) Benxi Shiqiaozi Development Zone (BSDZ)

Progress in cognitive neuroscientific studies of visual awareness

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Progress in Natural Science:Materials International 2009年第2期19卷 145-152页

作者： Qi li,Haiyan Geng Department of Psychology,peking university,beijing 100871,china [a]Department of Psychology Peking University Beijing 100871 China

The psychological and neural mechanisms of consciousness are among the most baffling problems in cognitive neuroscience. In this field,visual awareness is a topic that has been largely investigated,due to easy manipulation and measurable effects. The present arti-cle begins with the phenomena of dissociations between visual awareness and visual stimulus,visual awareness and visual attention,as well as visual awareness and vision-guided behavior,along with the corresponding experimental evidence. Furthermore,the neural mechanism of visual awareness is also discussed. It has been generally believed that visual awareness is the function of higher-order cerebral areas; however,recent discoveries have demonstrated that feedback from higher-to lower-order cortex areas is necessary for generating consciousness. The present article presents an in-depth analysis regarding this feedback process,and exploring its relation-ship with the generation and mechanisms of consciousness. Finally,theoretical controversies and discrepancies,as well as result con-flicts from various studies,have been collected,compared and discussed. Because the field of consciousness continues to be an extremely mysterious and complicated psychological phenomenon,there is a great need for further studies to explore and clarify this topic.

关键词： Visual awareness Neural mechanism Feedback process Cortical areas

Water demand for ecosystem protection in rivers with hyper-concentrated sediment-laden flow

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Science china(Technological sciences) 2004年第z1期47卷 186-198页

作者： LUO Huaming, li Tianhong, NI Jinren & WANG Yudong Department of Environmental Engineering, peking university, beijing 100871, china The Key Laboratory of Water and Sediment sciences, Ministry of Education, beijing 100871, china peking Univ Dept Environm Engn Beijing 100871 Peoples R China Key Lab Water & Sediment Sci Minist Educ Beijing 100871 Peoples R China

Sediment transport is one of the main concerns in a river system with hyper-concentrated flows. Therefore, the water use for sediment transport must be considered in study on the water demand for river ecosystem. The conventional methods for calculating the Minimum Water Demand for River Ecosystem (MWDRE) are not appropriate for rivers with high sediment concentration. This paper studied the MWDRE in wet season, dry season and the whole year under different water-and-sediment conditions in the Lower Yellow River, which is regarded as a typical river with sediment-laden flows. The characteristics of MWDRE in the river are analyzed. Firstly, the water demand for sediment transport (WDST) is much larger than the demands for other riverine functions, the WDST accounts for the absolute majority of the MWDRE. Secondly, in wet season when the WDST is satisfied, not only most of the annual incoming sediment can be transported downstream, but also the water demands for other river functions can be satisfied automatically, so that the MWDRE in wet season is identical to the WDST. Thirdly, in dry season, when the WDST is satisfied, the water demands for other river functions can also be satisfied, but the low sediment transport efficiency results in significant waste of water resources. According to these characteristics and aiming at decreasing sediment deposition in the riverbed and improving the utilization efficiency of water resources, hydrological engineering works can be used to regulate or control flow and sediment so that the sediment incoming in dry season can be accumulated and be transported downstream intensively and thus efficiently in wet season.

关键词： sediment-laden flow, the Lower Yellow River, water demand for river ecosystem, water demand for sediment transport

Balanced multiple description subband coding based on multifilter banks

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Science china(Information sciences) 2011年第11期54卷 2359-2372页

作者： WANG Ning 1,li BaoBin 2 & PENG liZhong 1 1 LMAM,School of mathematical sciences,peking university,beijing 100871,china 2 School of Information Science and Engineering,Graduate university of Chinese Academy of sciences,beijing 100190,china 1. LMAM School of Mathematical Sciences Peking University Beijing 100871 China2. School of Information Science and Engineering Graduate University of Chinese Academy of Sciences Beijing 100190 China

Multiple description coding is one of the source coding techniques to alleviate the problems of packet loss in *** encoder generates several different descriptions of the source and the decoder can produce a useful reconstruction with any received subset of these *** of the earlier works concentrated on redundancy and the average distortion of the single-description reconstructions,which is insufficient to describe the *** this paper,a metric of the coding system,balance eccentric modulus,is defined to evaluate the difference in quality between the individual *** the discrete wavelet transform becomes trivial polyphase transform when setting the balance eccentric modulus at zero,we introduce a multiwavelet based scheme ***,a sufficient condition for balanced multiwavelet based multiple description coding is presented.

关键词： multiple description coding rate-distortion theory balance eccentric modulus balanced multiwavelet multifilter bank

Anti-nociceptive role of neuropeptide Y in the nucleus accumbens in rats with inflammation, an effect modulated by mu- and kappa-opioid receptors

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Progress in Natural Science:Materials International 2006年第2期16卷 133-141页

作者： li Jinju and YU Longchuan (Laboratory of Neurobiology, College of life sciences, and National Laboratory of Biomembrane and Membrane Biotechnology, peking university, beijing 100871, china) [a]Laboratory of Neurabiology College of life Sciences and National Laboratory of Biomembrane and Membrane Biotechnology Peking University Beijing China

Recent study in our laboratory showed that neuropeptide Y (NPY) plays an antinociceptive role in the nucleus accum-bens (NAc) in intact rats. The present study was performed to further investigate the effect of NPY in nociceptive modulation in the NAc of rats with inflammation, and the possible interaction between NPY and the opioid systems. Experimental inflammation was induced by subcutaneous injection of carrageenan into the left hindpaw of rats. Intra-NAc administration of NPY induced a dose-dependent increase of hindpaw withdrawal latencies (HWLs) to thermal and mechanical stimulations in rats with inflammation. The anti-nociceptive effect of NPY was significantly blocked by subsequent intra-NAc injection of the Y1 receptor antagonist NPY28-36, suggesting an involvement of Y1 receptor in the NPY-induced anti-nociception. Furthermore, intra-NAc administration of the opioid antagonist naloxone significantly antagonized the increased HWLs induced by preceding intra-NAc injection of NPY, suggesting an involvement of the endogenous opioid system in the NPY-induced anti-nociception in the NAc during inflammation. Moreover, the NPY-induced anti-nociception was attenuated by following intra-NAc injection of the μ-opioid antagonist β-funaltrexamine (β-FNA), and κ-opioid antagonist nor-binaltorphimine (nor-BNI), but not by S-opioid antagonist naltrindole, indicating that μ- and K-opioid receptors, not S-opioid receptor, are involved in the NPY-induced anti-nociception in the NAc in rats with inflammation.

关键词： nucleus accumbens, neuropeptide Y, Y1 receptor, carrageenan anti-nociception, μ- and κ-opioid receptors.