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Establishment of apparent quantum yield and maximum ecosystem assimilation on Tibetan Plateau alpine meadow ecosystem

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Science china Earth sciences 2005年第Z1期48卷 141-147页

作者： XU Lingling, ZHANG Xianzhou, SHI Peili & YU Guirui Institute of Geographic sciences and Natural Resources Research, chinese Academy of sciences, beijing 100101, china graduate school of the chinese acedemy of sciences, beijing 100039, china Institute of Geographic sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China graduate school of the chinese acedemy of sciences Beijing 100039 China Institute of Geographic sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China

The alpine meadow is widely distributed on the Tibetan Plateau with an area of about 1.2×106km2. Damxung County, located in the hinterland of the Tibetan Plateau, is the place covered with this typical vegetation. An open-path eddy covariance system was set up in Damxung rangeland station to measure the carbon flux of alpine meadow from July to October, 2003. The continuous carbon flux data were used to analyze the relationship between net ecosystem carbon dioxide exchange (NEE) and photosynthetically active radiation (PAR), as well as the seasonal patterns of apparent quantum yield (α) and maximum ecosystem assimilation (Pmax). Results showed that the daytime NEE fitted fairly well with the PAR in a rectangular hyperbola function, with α declining in the order of peak growth period (0.0244 μmolCO2 · μmol-1PAR) > early growth period > seed maturing period > withering period (0.0098 μmolCO2 · μmol-1PAR). The Pmax did not change greatly during the first three periods, with an average of 0.433 mgCO2 · m-2 · s-1,i.e. 9.829 μmolCO2 · m-2 · s-1. However, during the withering period, Pmax was only 0.35 mgCO2 · m-2 · s-1, i.e. 7.945 μmolCO2 · m-2 · s-1. Compared with other grassland ecosystems, the α of the Tibetan Plateau alpine meadow ecosystem was much lower.

关键词： Tibetan Plateau, alpine meadow ecosystem, eddy covariance, apparent quantum yield, maximum ecosystem assimilation.

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Effects of cosmological constant on motion of UHECR particles

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Science china(Physics,Mechanics & Astronomy) 2005年第1期48卷 44-56页

作者： CHEN Shaoxia & CHANG Zhe Institute of High Energy Physics, chinese Academy of sciences, beijing 100039, china graduate school of chinese Academy of sciences, beijing 100039, china Institute of High Energy Physics Chinese Academy of Sciences Beijing 100039 China graduate school Chinese Academy of Sciences Beijing 100039 China

Recent astronomical observations manifest that about two-thirds of the whole energy in the Universe is contributed by a small positive cosmological constant A (> 0). Then, an asymptotically de Sitter spacetime is premised naturally. However, physics in the de Sitter spacetime is very different from that in the Minkowski spacetime. As the first step, a covariant formalism of the kinematics in the de Sitter spacetime is presented here. By solving exactly the equations of motion for a field, we obtain the dispersion relation of a free particle. It is noticed that the dispersion relation is dependent on the degree of freedom of angular momentum of the particle. We show the threshold anomaly of the ultra high energy cosmic ray disappears naturally in the framework of the de Sitter kinematics.

关键词： ultrahigh energy cosmic ray, cosmological constant, curved spacetime.

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Recent advances in the data analysis method of functional magnetic resonance imaging and its applications in neuroimaging

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Progress in Natural Science:Materials International 2006年第8期16卷 785-795页

作者： TIAN Jie, YANG Lei and HU Jin (Institute of Automation, chinese Academy of sciences, beijing 100080, china graduate school of chinese Academy of sciences, beijing 100039, china) [a]chinese Academy of sciences Institute of Automation Beijing China [b]graduate school of chinese Academy of sciences Beijing China

Functional magnetic resonance imaging (fMRI) has opened a new area to explore the human brain. The fMRI can reveal the deep insights of spatial and temporal changes underlying a broad range of brain function, such as motor, vision, memory and emotion, all of which are helpful in the clinical investigation. In this paper, we introduce some recent-developed algorithms for fMRI signal detection such as model-driven method (general linear model, deconvolution model, non-linear model, etc. ) and data-driven method (principle component analysis, independent component analysis, self-organization mapping, clustered constrained non-negative matrix factorization, etc. ). We also propose several important applications of neuroimaging and point out their shortcomings and future perspectives.

关键词： fMR1 data analysis neuroimaging.

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Twistor bundle theory and its application

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Science china Mathematics 2004年第4期47卷 605-616页

作者： PENG Chia-Kuei & TANG ZizhouDepartment of Mathematics, graduate school of chinese Academy of sciences, beijing 100039, china Department of Mathematical sciences, Tsinghua University, beijing 100084, china 1. Department of Mathematics Graduate School of Chinese Academy of Sciences 100039 Beijing China 2. Department of Mathematical sciences Tsinghua University 100084 Beijing China

Over an oriented even dimensional Riemannian manifold(M 2m ,ds2 ), in terms of the Levi-Civita connection form Ω and the canonical form Θ on the bundle of positive orthonormal frames, we give a detailed description of the twistor bundle Гm = SO(2m)/U(m)? J +(@#@ M,ds2 ) →M. The integrability on an almost complex structureJ compatible with the metric and the orientation, is shown to be equivalent to the fact that the corresponding cross section of the twistor bundle is holomorphic with respect toJ and the canonical almost complex structureJ 1 onJ +(M,ds2 ), by using moving frame theory. Moreover, for various metrics and a fixed orientation onM, a canonical bundle isomorphism is established. As a consequence, we generalize a celebrated theorem of LeBrun.

关键词： almost complex structure, integrability, twistor bundle.

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Reconstruction of temperature series in china for the last 5000 years

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Progress in Natural Science:Materials International 2006年第8期16卷 838-845页

作者： GE Quansheng, WANG Shunbing and ZHENG Jingyun (Institute of Geographical sciences and Natural Resources Research, chinese Academy of sciences, beijing 100101, china graduate school of the chinese Academy of sciences, beijing 100039, china) [a]chinese Academy of sciences Institute of Geographical Sciences and Natural Resources Research Beijing China [b]graduate school of the chinese Academy of sciences Beijing China

A temperature series with a 100 year resolution for the last 5000 years in china has been reconstructed by using 31 longterm temperature proxy series selected from recent publications in the last 20 years. The proxy records include pollens, stalagmites, lake-sediments, peat, ice cores and historical documents. The result reveals that in the millennial scale temperature variation it was warm in 3050-250 BC and it was cold in 250 BC-1950 AD. In the above two periods there were many stages of sub-scale temperature fluctuations. The result also shows an obvious temperature discrepancy on the century to multi-century scale between the Eastern Monsoon Region, the Qinghai-Tibet Region and the Northwestern Region in 2850 BC, 2350 BC, 1350 BC, 950-350 BC, 50-250 AD, and 550 AD. A comparison between the reconstructed series of this paper and some North Hemisphere temperature series indicates that in the longterm scale change, the temperature change in china is in phrase with that of the Northern Hemisphere during the last 5000 years, while on the century to multi-century scale there are differences at the beginning and end times, which may imply that temperature change does not occur simultaneously in different regions.

关键词： temperature series the last 5000 years china.

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Rate of strong consistency of quasi maximum likelihood estimate in generalized linear models

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Science china Mathematics 2004年第6期47卷 882-893页

作者： YUE Li & CHEN Xiru school of Mathematics and Statistics, Wuhan University, Wuhan 430072, china graduate school, chinese Academy of sciences, beijing 100039, china 1. school of Mathematics and Statistics Wuhan University 430072 Wuhan China 2. graduate school Chinese Academy of Sciences 100039 Beijing China

Under the assumption that in the generalized linear model (GLM) the expectation of the response variable has a correct specification and some other smooth conditions, it is shown that with probability one the quasi-likelihood equation for the GLM has a solution when the sample size n is sufficiently large. The rate of this solution tending to the true value is determined. In an important special case, this rate is the same as specified in the LIL for iid partial sums and thus cannot be improved anymore.

关键词： quasi-likelihood function generalized linear models strong consistency

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Identification of novel SINEs from Cyprinidae and their evolutionary significance

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Progress in Natural Science:Materials International 2007年第3期17卷 270-279页

作者： HAN Yawei, HE Slumping and CHEN Yiyu ( Institute of Hydrobiology, chinese Academy of sciences, Wuhan 430072, china. graduate school, chinese Academy of sciences, beijing 100039, china) [a]Institute of Hydrobiology Chinese Academy of Sciences Wuhan China [b]graduate school Chinese Academy of Sciences Beijing China

Short interspersed nuclear elements (SINEs) are widespread among eukaryotic genomes. They are repetitive DNA sequences that have been amplified by retrotransposition. In this study, a class of SINEs were isolated from the Opsariichthys bidens genome, and named Opsar. Sequence analysis confirmed that Opsar is a new class of typical SINEs derived from tRNA molecules. With the tRNA-derived region of Opsar and through BLASTN search, we further identified Zb-SINEs from the zebrafish genome, which includes two groups: Zb-SINE-A and Zb-SINE-B. The Zb-SINE-A. group comprises subfamilies of -Al--A5, and the Zb-SINE-B group is a dimer of the tRNA -derived region and shares a similar dimeric composition to Alu. Zb-SINEs are composed of three distinct regions: a 5’ end tRNA-derived region, a tRNA-unrelated region and a 3’ end AT-rich region. The flanking regions are AT rich. The average length of Zb-SINEs elements is about 340 bp. Zb-SINEs account for as much as 0.1 % of the whole zebrafish genome. About 70% of the Zb-SINEs are on chromosomes 11, 18, and 19. These Zb-SINEs were characterized by PCR and dot hybridization. The distribution pattern of Zb-SINEs in genome strongly supports the master genes model. The tRNA-derived regions of Opsar and Zb-SINEs were compared with the tRNAAla gene, and they showed 76% similarity, indicating that Opsar and Zb-SINEs originated from an inactive tRNA sequence or a tRNA -like sequence. In view of the evolutionary status of zebrafish in the Cyprinidae, we deduced that Zb-SINEs were a very old class of interspersed sequences.

关键词： short interspersed nuclear elements (SINEs) master gene model Opsar Zb-SINEs and Cyprinidae.

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Isolation and Characterization of Photosystem Ⅱ of Porphyra yezoensis Ueda

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Acta Biochimica et Biophysica Sinica 2004年第11期36卷 780-785页

作者： Zheng-Quan GAO, Guang-Ce WANG, and Cheng-Kui TSENGKey Laboratory of Experimental Marine Biology, Institute of Oceanology, the chinese Academy of sciences, Qingdao 266071, china graduate school, the chinese Academy of sciences, beijing 100039, china Key Laboratory of Experimental Marine Biology Institute of Oceanology the Chinese Academy of SciencesQingdao 266071 China graduate school the Chinese Academy of SciencesBeijing 100039 China

The thylakoid membranes were isolated and purified from gametophyte of Porphyra yezoensis Ueda (P. yezoensis) by sucrose density gradient ultracentrifugation. After P. yezoensis gametophyte thylakoid membranes were so... 详细信息

关键词： red algae Porphyra yezoensis Ueda photosystem Ⅱ polypeptide composition extrinsic protein

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Genetic fingerprinting of plankton community provides new insights into aquatic ecology

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Progress in Natural Science:Materials International 2006年第9期16卷 893-898页

作者： YAN Qingyun, YU Yuhe and FENG Weisong ( Institute of Hydrobiology, chinese Academy of sciences, Wuhan 430072, china graduate school of the chinese Academy of Sci-ences, beijing 100039, china) [a]Institute of Hydrobiology Chinese Academy of Sciences Wuhan China [b]graduate school of the chinese Academy of sciences Bejing China

Over the past two decades, molecular techniques have been widely used in ecological study and molecular ecology has been one of the most important branches of ecology. Meanwhile, genetic fingerprinting analyses have significantly enhanced our knowledge of the diversity and evolutionary relations of the planktonic organisms. Compared with conventional approaches in ecological study (e.g. morphological classification), genetic fingerprinting techniques are simpler and much more effective. This review provides an overview of the principles, advantages and limitations of the commonly used DNA fingerprinting techniques in plankton research. The aim of this overview is to assess where we have been, where we are now and what the future holds for solving aquatic ecological problems with molecular-level information.

关键词： genetic fingerprinting plankton community aquatic ecology genetic diversity.

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A novel operation mode for spaceborne polarimetric SAR

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Science china(Information sciences) 2011年第4期54卷 884-897页

作者： QI WeiKong 1,2 & YU WeiDong 1 1 Institute of Electronics,chinese Academy of sciences,beijing 100190,china 2 graduate school of chinese Academy of sciences,beijing 100039,china 1. Institute of Electronics Chinese Academy of Sciences Beijing 100190 China2. Graduate School of Chinese Academy of Sciences Beijing 100039 China

A novel operation mode for spaceborne polarimetric SAR,named polarization space-division adding polarization code-division (PSD-PCD) operation mode,is proposed in this paper through combining polarimetric SAR with elevation digital beam-forming (DBF) on *** a pulse repetition interval the up-chirp LFM sub-pulse is transmitted with horizontal polarization antenna,and with some delay the down-chip LFM subpulse is transmitted with vertical polarization antenna to realize code *** every sub-aperture receives returns from ground,SAR system uses range DBF to separate echoes relative to different sub-pulses in order to realize space *** system PRF is equal to that of single-polarization SAR,and elevation DBF help reduce range ambiguity ***,the main system parameters,including PRF,delay between two sub-pulses,radar equation and ambiguity are analyzed and compared with those of single-polarization *** results demonstrate the feasibility and validity of PSD-PCD operation mode.

关键词： spaceborne synthetic aperture radar (SAR) polarimetry digital beamforming (DBF) operation mode ambiguity ratio polarization space-division polarization code-division

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