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The role of periphytes in the shift between macrophyte and phytoplankton dominated systems in a shallow,eutrophic lake (Lake Taihu,China)

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Science China(Life Sciences) 2006年第6期49卷 597-602页

作者： QIN Boqiang SONG Yuzhi GAO Guang Nanjing Institute of Geography & Limnology Chinese Academy of Sciences Nanjing 210008 China Nanjing Institute of Geography & Limnology Chinese Academy of Sciences Nanjing 210008 China Nanjing Institute of Geography & Limnology Chinese Academy of Sciences Nanjing 210008 China

Based on experiments of periphyte response to different trophic levels and their impact on macrophyte production,it was found that the periphyte biomass increased with the nutrient con-centrations. Increased trophic level and periphyte biomass resulted in decreased macrophyte photo-synthesis. It was suggested that the periphytes could cause resilience and hysteresis in the system shifts between macrophyte and phytoplankton domination. Other factors,such as fish farming,storm induced waves and mechanical destruction,and high water levels could be the perturbations during the system shifts,but these are not the key factors. Instead,the nutrient loading and periphyte abundance could determine the shift in lake ecosystem between macrophyte and phytoplankton domination. This finding could theoretically elucidate the mechanism of ecosystem shifts between macrophyte and phytoplankton domination.

关键词： shallow lake, eutrophication, ecosystem shift, macrophyte, phytoplankton.

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Precise measurement of magnetic moment of short-lived β-emitting nuclei ^(12)B (I~π=1^+,T_(1/2)=20.18 ms)

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Science China(Physics,Mechanics & Astronomy) 2004年第5期47卷 531-539页

作者： M. Mihara M. Fukuda K. Matsuta T. Minamisono Graduate School of Science Osaka University Toyonaka Osaka 560-0043 JapanGraduate School of Science Osaka University Toyonaka Osaka 560-0043 JapanGraduate School of Science Osaka University Toyonaka Osaka 560-0043 JapanGraduate School of Science Osaka University Toyonaka Osaka 560-0043 Japan

The spin polarized -emitting nuclei 12B (I p = 1+, T1/2 = 20.18 ms) were produced by the nuclear reaction 11B(d, p) 12B and by the selection technique of the incident deuteron energy and the 12B recoil angle following the nuclear reaction. The nuclear magnetic moment of the short-lived nuclei 12B was measured by ?NMR with the -NMR and -NQR setup established for the first time in China. The nuclear magnetic moment of 12B was determined to be = 0.99993 0.00048 nm or g = 0.99993 0.00048 after the precise correction of the Knight shift.

关键词： short-lived 12B (Iπ = 1+, T1/2 = 20.18 ms) nuclei, nuclear magnetic moment, Knight shift, β-NMR.

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Energy Spectra, g Factors and Their Pressure-Induced and/or Thermal shifts of SrTiO3:Cr3+ and SrTiO3:Mn4+ Ⅲ: R-Line Thermal shifts of SrTiO3:Mn4+

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Communications in Theoretical Physics 2001年第11期36卷 463-468页

作者： MA Dong-Ping ZHANG Ji-Ping Department of Applied Physics Sichuan University Chengdu 610065 China International Centre for Materials Physics The Chinese Academy of Sciences Shenyang 110015 China Department of Applied Physics Sichuan University Chengdu 610065 China

By taking into account all the irreducible representations and their components in the electron-phonon interaction (EPI) as well as all the levels and the admixtures of basic wavefunctions within d3 electronic configuration,the values of the parameters in the expressions of thermal shift (TS) from EPI for the ground level, R level and R line of SrTiO3:Mn4+ have been evaluated; the R-line TS and various contributions to it have been calculated in the low-temperature region. It is found that all the three terms of R-line TS from EPI relevant to the lattice vibration are red shifts. The Raman term is the largest, the neighbor-level term is the second, and the optical-branch term is very small over the range of T ≤ 80 K. The contribution to R-line TS from thermal expansion has been approximately neglected in this work. The very strong EPI relevant to its lattice vibration for SrTiO3:Mn4+ causes its R-line TS to be an unusually large red-shift. Only by taking into account the strong softening of the low-frequency acoustic modes of the lattice vibration at low temperatures, can we successfully explain the variation of R-line TS of SrTiO3:Mn4+ with temperature.

关键词： crystal fields, optical properties, electron-phonon interaction, thermal shift, softening of acoustic modes

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Relative importance of wind and buoyancy forcing for interdecadal regime shifts in the Pacific Ocean

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Science China Earth Sciences 2003年第5期46卷 417-427页

作者：王东晓王佳吴立新刘征宇 LaboratoryofTropicalMarineEnvironmentalDynamics SouthChinaSeaInstituteofOceanologyChineseAcad-emyofSciences InternationalArcticResearchCenter UniversityofAlaska DepartmentofAtmosphericandOceanicSciences UniversityofWisconsin-Madison

Miami Isopycnal Coordinate Ocean Model (MICOM) is applied here to simulate the interdecadal climatic change in the Pacific Ocean. The surface forcing functions from January 1945 through to December 1993 are derived from the Comprehensive Ocean and Atmospheric Data Set (COADS). Such a numerical experiment reproduces the observed basin-wide evolution for the interdecadal variability of the heat content in the upper 400 m layers. The teleconnections between the central North Pacific, the Gulf of Alaska, and the eastern and western tropical Pacific Oceans are captured very well. Two additional experiments are performed to investigate the rela-tive importance of anomalous wind and buoyancy forcing regarding the regime shift. The results show that the anomalous buoyancy forcing is the dominant factor in the North Pacific and the sub-tropics, whereas the anomalous wind forcing is more important in the tropical Pacific than the other factors. Subduction is intrinsic physics for the interdecadal variability in the midlatitudes and the northern subtropics, whereas other mechanisms are involved in the tropical Pacific.

关键词： Pacific Ocean, regime shift, relative importance, buoyancy forcing.

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