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Vanishing Theorem for Irreducible Symmetric Spaces of Noncompact Type

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Acta Mathematica Sinica,English Series 2010年第2期26卷 361-368页

作者： Xu sheng liu School of Mathematical Sciences Fudan University Shanghai 200433 P. R. China

We prove the following vanishing theorem. Let M be an irreducible symmetric space of noncompact type whose dimension exceeds 2 and M ≠SO0（2, 2）/SO（2） × SO（2）. Let π ： E →＊ M be any vector bundle. Then any E-valued L2 harmonic 1-form over M vanishes. In particular we get the vanishing theorem for harmonic maps from irreducible symmetric spaces of noncompact type.

关键词： vanishing theorem symmetric space harmonic form

Cu and Zn Isotopic Evidence for the Magnitude of Organic Burial in the Mesoproterozoic Ocean

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Journal of Earth Science 2022年第1期33卷 92-99页

作者： Yiwen Lü sheng-Ao liu State Key Laboratory of Geological Processes and Mineral Resources and Institute of Earth SciencesChina University of GeosciencesBeijing 100083China

The rate of net primary production in the Proterozoic ocean was suggested to be no more than 10% of its modern value(Laakso and Schrag,2019),however,in the Mesoproterozoic Xiamaling Formation,the export production values could reach 20%-150% of the present-day Equatorial Atlantic average values(Zhang et al.,2016).Here,we report Zn and Cu isotope data for black shales from the Xiamaling Formation to illustrate the biogeochemical cycling of Zn and Cu in the Mesoproterozoic *** ^(65)Cu-enriched signature in the authigenic fraction is similar to that in bioauthigenic Cu of the modern marine *** Zn isotope ratios of sediments deposited in euxinic conditions are commonly higher than those of clastic sediments,indicating light Zn sinks in the coeval *** with previously reported Mo isotope data,the proportion of organic carbon to total carbon burial in the Mesoproterozoic was about as half as that at present,which is larger than the previous estimation―a quarter of today’s value(e.g.,Ozaki et al.,2019) and is evidenced by a wide distribution of black *** organic burial may be ascribed to the increasing phosphorus inputs from large igneous provinces and consequently high primary productivity,which has spurred the hypothesized atmosphere-ocean oxygenation at ~1.4 Ga.

关键词： zinc isotopes organic carbon Xiamaling Formation

Copper Isotope Fractionation during Basalt Leaching at 25℃ and pH=0.3,2

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Journal of Earth Science 2022年第1期33卷 82-91页

作者： Dandan Li sheng-Ao liu State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesBeijing 100083China

The geochemical cycling of copper in the hydrosphere and soil environments primarily involves the transport of Cu from rocks to rivers via *** the factors controlling Cu isotope fractionation during weathering is crucial for the purpose of using Cu isotopes as a tracer of geochemical ***,we performed acid-leaching experiments on natural basalts (BHVO-2 and GBW07105) and chalcopyrite in Erlenmeyer flasks at T=25℃ and different pH values (0.3 and 2).Our results reveal substantial Cu isotope fractionations (△^(65)Cu_(solution-initial)) between leachates (Cu_(solution)) and starting materials (Cu_(initial)).The leachates released from GBW07105 and chalcopyrite are consistently enriched in heavier Cu isotopes relative to the starting materials at pH=***,the δ^(65)Cu_(solution)values decrease to about-0.6‰first,then increase to>0 for BHVO-2 at pH=2 and GBW07105 at pH=*** results indicate that leaching of natural rocks by acidic liquids can produce both positive and negative Cu isotope fractionation,depending on pH values and the types of minerals in starting materials.X-ray power diffraction analysis (XRD) patterns reveal similar mineral assemblages between starting basalts and residues after each reaction *** most likely mechanisms responsible for such Cu isotope fractionation are the relative rates of Cu oxidation at the surface and Cu release into solution,and the sequence of mineral *** study represents an important step for future studies to use Cu isotopes to explain Cu isotopic variations in natural rocks and waters.

关键词： Cu isotopes isotope fractionation basalt chalcopyrite leaching

2D DOA Estimation Algorithm with Increased Degrees of Freedom for Two Parallel Linear Arrays

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China Communications 2020年第6期17卷 101-108页

作者： sheng liu Jing Zhao School of Data Science Tongren UniversityTongren 554300China

In this paper,a two-dimensional(2 D)direction-of-arrival(DOA)estimation algorithm with increased degrees of freedom for two parallel linear arrays is *** different from the conventional two-parallel linear array,the proposed two-parallel linear array consists of two uniform linear arrays with non-equal inter-element *** method(PM)is used to obtain a special matrix which can be utilized to increase the virtual elements of one of uniform linear ***,the PM algorithm is used again to obtain automatically paired elevation and azimuth *** simulation results and complexity analysis show that the proposed method can increase the number of distinguishable signals and improve the estimation precision without increasing the computational complexity.

关键词： direction-of-arrival(DOA)estimation two parallel linear arrays PM algorithm

Tomato yellow leaf curl virus infection of tomato does not affect the performance of the Q and ZHJ2 biotypes of the viral vector Bemisia tabaci

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Insect Science 2011年第1期18卷 40-49页

作者： Meng Li Jian liu Shu-sheng liu Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects Institute of Insect Sciences Zhejiang UniversityHangzhou China

To better understand the etiology of begomovirus epidemics in regions under invasion we need to know how indigenous and invasive whitefly vectors respond to virus infection. We investigated both direct and indirect effects of infection with Tomato yellow leaf curl virus （TYLCV） on the performance of the invasive Q biotype and the indigenous Asian ZHJ2 biotype of whitefly Bemisia tabaci. The Q biotype performed better than the ZHJ2 biotype on either uninfected or virus-infected tomato plants. However, virus-infection of host plants did not, or only marginally affected, the performance of either biotype of whiteflies in terms of fecundity, longevity, survival, development and population increase. Likewise, association of the vectors with TYLCV did not affect fecundity and longevity of the Q or ZHJ2 biotypes on cotton, a non-host of TYLCV. These results indicate that the alien Q biotype whitefly, but not the indigenous ZHJ2 biotype, is likely to become the major vector of TYLCV in the field and facilitate virus epidemics.

关键词： Bemisia tabaci performance tomato Tomato yellow leaf curl virus virusinfection

Optimal Investment and Excess of Loss Reinsurance with Short-selling Constraint

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Acta Mathematicae Applicatae Sinica 2011年第3期27卷 527-534页

作者： sheng liu Jing-xiao Zhang Center for Applied Statistics School of Statistics Renmin University of China Beijing 100872 China

This paper considers the optimal control problem with constraints for an insurance company. The risk process is assumed to be a jump-diffusion process and the risk can be reduced through an excess of loss （XL） reinsurance. In addition, the surplus can be invested in the financial market. In the financial market, the short-selling constraint is one of the main factors which make models more realistic. Our goal is to find the optimal investment-reinsurance policy without short-selling, which maximizes the expected exponential utility of the terminal wealth. By solving the corresponding Hamilton-Jacobi-Bellman equation, the value function and the optimal investment-reinsurance policy are given in a closed form.

关键词： Hamilton-Jacobi-Bellman equation jump-diffusion process short-selling constraint XL reinsurance

Copper isotope constraints on the origins of basaltic and andesitic magmas in the Tengchong volcanic field,SE Tibet

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Geoscience Frontiers 2024年第4期15卷 290-303页

作者： Yuan-Ru Qu sheng-Ao liu State Key Laboratory of Geological Processes and Mineral Resources China University of GeosciencesBeijing 100083China

The Tengchong volcano field(TVF),situated at the southeastern margin of the Tibetan Plateau,holds crucial information regarding Cenozoic volcanic activities and geotectonic evolution of the SE *** provide new constraints on petrogenesis and evolution of the Tengchong volcanism,here we conducted copper(Cu)elemental and isotopic analyses on a suite of samples that document the evolution from basalts to andesites in the *** basalts are Cu-depleted(29.7-36.9 ppm)and have higherδ65Cu val-ues(0.19‰-0.40‰,mean=0.31‰±0.05‰;n=11)than those of mid-ocean ridge basalts(MORBs,~0.09‰)and the mantle(~0.06‰)as well as the majority of island arc *** with the low Cu/Zr ratios,these characteristics are interpreted to reflect the fractionation of isotopically light sulfides in the S-saturated systems during magma ascent,rather than source heterogeneity induced by recycled materials and redox *** with the basalts,the andesites have slightly lower Cu contents(14.4-29.4 ppm)and lighter Cu isotopic compositions(mean=-0.14‰±0.06‰;n=13).These differences cannot be attributed to progressive sulfide fractionation of basaltic magmas but require the assimilation of lower crustal materials with lowδ65Cu values during evolution of the andesitic *** results collectively suggest that Cu isotopes can provide valuable insights into magma origin and evolution.

关键词： Copper isotopes Sulfide segregation Magmatic differentiation Tengchong volcanic field

Linking deep CO2 outgassing to cratonic destruction

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National Science Review 2022年第6期9卷 12-22页

作者： Zhao-Xue Wang sheng-Ao liu Shuguang Li Di liu Jingao liu State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences

Outgassing of carbon dioxide from the Earth's interior regulates the surface climate through deep *** we examine the role of cratonic destruction in mantle CO2outgassing via collating and presenting new data for Paleozoic kimberlites, Mesozoic basaltic rocks and their mantle xenoliths from the eastern North China Craton（NCC）, which underwent extensive destruction in the early Cretaceous. High Ca/Al and low Ti/Eu and δ26Mg are widely observed in lamprophyres and mantle xenoliths, which demonstrates that the cratonic lithospheric mantle（CLM） was pervasively metasomatized by recycled *** analysis of bubble-bearing melt inclusions shows that redox melting of the C-rich CLM produced carbonated silicate melts with high CO2content. The enormous quantities of CO2in these magmas,together with substantial CO2degassing from the carbonated melt–CLM reaction and crustal heating,indicate that destruction of the eastern NCC resulted in rapid and extensive mantle CO2emission, which partly contributed to the early Cretaceous greenhouse climate episode.

关键词： carbonate metasomatism lithospheric mantle CO_2 outgassing deep carbon cycling cratonic destruction North China Craton

Three-dimensional gravity inversion based on optimization processing from edge detection

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Geodesy and Geodynamics 2022年第5期13卷 503-524页

作者： sheng liu Shuanggen Jin Qiang Chen Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China School of Remote Sensing and Geomatics Engineering Nanjing University of Information Science and TechnologyNanjing 210044China

Gravity inversion requires much computation,and inversion results are often *** first problem is often due to the large number of grid *** detection method,i.e.,tilt angle method of analytical signal amplitude(TAS),helps to identify the boundaries of underground geological anomalies at different depths,which can be used to optimize the grid and reduce the number of grid *** requirement of smooth inversion is that the boundaries of the meshing area should be continuous rather than *** this paper,the optimized meshing strategy is improved,and the optimized meshing region obtained by the TAS is changed to a regular region to facilitate the smooth *** the second problem,certain constraints can be used to improve the accuracy of *** results of analytic signal amplitude(ASA)are used to delineate the central distribution of geological *** propose a new method using the results of ASA to perform local constraints to reduce the non-uniqueness of *** guided fuzzy c-means(FCM)clustering algorithm combined with priori petrophysical information is also used to reduce the non-uniqueness of gravity *** Open Acc technology is carried out to speed up the computation for parallelizing the serial program on *** general,the TAS is used to reduce the number of grid *** local weighting and priori petrophysical constraint are used in conjunction with the FCM algorithm during the inversion,which improves the accuracy of *** inversion is accelerated by the Open Acc technology on *** proposed method is validated using synthetic data,and the results show that the efficiency and accuracy of gravity inversion are greatly improved by using the proposed method.

关键词： Gravity inversion Locally weighted constraint Petrophysical constrain Fuzzy c-means clustering algorithm Open Acc technology