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Size variation of the end Permian conodont Neogondolella at Meishan section,Changxing,Zhejiang and its significance

Science China Earth Sciences 2006年第4期49卷 337-347页

作者： LUO Genming LAI Xulong JIANG Haishui ZHANG Kexin Faculty of Earth Sciences China University of Geosciences Wuhan 430074 China Faculty of Earth Sciences China University of Geosciences Wuhan 430074 China Faculty of Earth Sciences China University of Geosciences Wuhan 430074 China Faculty of Earth Sciences China University of Geosciences Wuhan 430074 China

This study is based on both a generic and species level investigation of the individual size of the latest Permian conodont Neogondolella Pa elements collected from Meishan section A, Changxing, Zhejiang Province. In this study, an obvious size reduction of Neogondolella Pa elements within bed 24e of the upper Changxing Limestone is recognized. The size variation of the Neogon- dolella occurs simultaneously with some important events including the negative shift of δ 13C, change in the ratio of the abundance of cyanobacterial biomarkers versus that of other general bacterial biomarkers and the shallowing of the sea water. Through the investigation of the paleoenvironmental changes and the analysis of the paleoecology of the conodont genus Neogondolella, the authors propose that the major factors for the size reduction of species of the conodont genus Neogondolella are food shortages caused by the mass extinction, the shallowing of the sea water as well as the in- crease in opacity of the sea water during the end Permian. The same phenomenon of Neogondolella size reduction is also observed in preliminary research from the same horizon at Shangsi section, Sichuan Province. All the evidence suggests that there was a mass extinction that occurred at the horizon of bed 24e, and the evidence supports the viewpoint of a multi-phase mass extinction during the Permian and Triassic transition in South China.

关键词： Meishan section, end Permian, conodont, Neogondolella, size reduction.

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Rare Complication of External Ventricular Drainage：Intra-ventricular Drain section

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Journal of Health Science 2014年第12期2卷 588-590页

作者： Hanane Ezzouine Abdellatif Benslama Medical Intensive Care Unit University Teaching Hospital Ibn Rushd 1 Quartier des Hopitaux Casablanca 20200 Morocco

The external ventricular derivation is an invasive technique used to cure ***,it may have infectiousand mechanical complications and needs specific *** rarely, the drain line can be cut with an intraventricular sectio...

关键词： External ventricular drainage, section, rare complication.

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Absorption of electromagnetic waves by the dust particles in a plasma

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Science China(Technological Sciences) 2004年第4期47卷 461-469页

作者： LI Fang LI Lianlin SUI Qiang Institute of Electronics Chinese Academy of Sciences Beijing 100080 China Institute of Electronics Chinese Academy of Sciences Beijing 100080 China Institute of Electronics Chinese Academy of Sciences Beijing 100080 China

Absorption of electromagnetic waves by the dust particles in a plasma has been studied based on a Mie-Debye scattering mode. The longitudinal field of the Debye scattering has been derived and the wave energy loss from it has been calculated. It is shown that the lower the temperature of the plasma is and the higher the density of the plasma is, the larger the absorption cross section will be due to the longitudinal scattering. For the low frequency waves the electromagnetic waves scattered in a dusty plasma are mainly in the form of Debye scattering. In this case the energy loss due to the longitudinal scattering will affect the wave propagation seriously.

关键词： dusty plasma, Mie-Debye scatter, absorption cross section, total section.

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Probing proton halo of the exotic nucleus ^(28)S by elastic electron scattering

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Science China(Physics,Mechanics & Astronomy) 2004年第1期47卷 42-51页

作者： WANG Zaijun1 & REN Zhongzhou1’2 1. Department of Physics, Nanjing University, Nanjing 210008, China 2. Center of Theoretical Nuclear Physics, National Laboratory of Heavy-Ion Accelerator at Lanzhou, Lanzhou 730000, China Correspondence should be addressed to Ren Zhongzhou (email: zren@*** zren99@***) Received June 16, 2003 1. Department of Physics Nanjing University 210008 Nanjing China 2. Center of Theoretical Nuclear Physics National Laboratory of Heavy-Ion Accelerator at Lanzhou 730000 Lanzhou China

Elastic electron scattering on the exotic light nucleus 28S is investigated in the plane wave Born approximation. The variation of the squared form factors of 28S with momentum transfer is compared with that of 32S. It is found that the behavior of the form factors near the second minimum (with a moderate momentum transfer) is sensitive to the alteration of the charge density distribution of halo protons in 28S. This indicates that elastic electron scattering can be a good probe of the structure of proton-halo nuclei.

关键词： elastic electron scattering, cross section, form factor, proton-halo nucleus.

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An accurately delineated Permian-Triassic Boundary in continental successions

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Science China Earth Sciences 2007年第9期50卷 1281-1292页

作者： YIN HongFu1, YANG FengQing2, YU JianXin2, PENG YuanQiao1, WANG ShangYan3 & ZHANG SuXin1 1 Laboratory of Biological and Environmental Geology, China University of Geosciences, Wuhan 430074, China 2 State Key Laboratory of Geological Process and Mineral Resources, China University of Geosciences, Wuhan 430074, China 3 Geological Survey of Guizhou Province, Guiyang 550011, China 1. Laboratory of Biological and Environmental Geology China University of Geosciences Wuhan 430074 China 2. State Key Laboratory of Geological Process and Mineral Resources China University of Geosciences Wuhan 430074 China 3. Geological Survey of Guizhou Province Guiyang 550011 China

The Permian-Triassic Boundary Stratigraphic Set (PTBST), characteristic of the GSSP section of Meishan and widespread in marine Permian-Triassic Boundary (PTB) sequences of South China, is used to trace and recognize the PTB in a continental sequence at Chahe (Beds 66f―68c). Diversified Permian plant fossils extended to the PTBST, and a few relicts survived above that level. Sporomorphs are dominated by fern spores of Permian nature below the PTBST, above which they are replaced by gymnosperm pollen of Triassic aspect. In the nearby Zhejue section, the continental PTBST is charac- terized by the fungal 'spike' recorded in many places throughout the world. The boundary claybeds (66f and 68a,c) of the PTBST are composed of mixed illite-montmorillonite layers analogous with those at Meishan. They contain volcanogenic minerals such as β quartz and zircon. U/Pb dating of the upper claybed gives ages of 247.5 and 252.6 Ma for Beds 68a and 68c respectively, averaging 250 Ma. In con- trast to the situation in Xinjiang and South Africa, the sediment sequence of the Permian-Triassic tran- sition in the Chahe section (Beds 56―80) become finer upward. Shallowing and coarsening upward is not, therefore, characteristic of the Permian-Triassic transition everywhere. The occurrence of relicts of the Gigantopteris Flora in the Kayitou Fm. indicates that, unlike most marine biota, relicts of this pa- leophytic flora survived into the earliest Triassic. It is concluded that Bed 67 at Chahe corresponds to Bed 27 at Meishan, and that the PTB should be put within the 60-cm-thick Bed 67b④, now put at its base tentatively. This is the most accurate correlation of the PTB in continental facies with that in the marine GSSP.

关键词： Permian-Triassic Boundary, terrestrial sequence, U-Pb age, Chahe section, accuracy

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The dynamical properties of Rydberg hydrogen atom near a metal surface

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Science China(Physics,Mechanics & Astronomy) 2005年第6期48卷 667-675页

作者： GE Meihua1, ZHANG Yanhui1, WANG Dehua2, DU Mengli3 & LIN Shenglu1 1. College of Physics and Electronics, Shandong Normal University, Jinan 250014, China 2. Department of Mathematics and Physics, Shandong Institute of Architecture and Engineering, Jinan 250014, China 3. Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100080, China 1. College of Physics and Electronics Shandong Normal University 250014 Jinan China 2. Department of Mathematics and Physics Shandong Institute of Architecture and Engineering 250014 Jinan China 3. Institute of Theoretical Physics Chinese Academy of Sciences 100080 Beijing China

The dynamical properties of Rydberg hydrogen atom near a metal surface are presented by using the methods of phase space analysis and closed orbit theory. Transforming the coordinates of the Hamiltonian, we find that the phase space of the system is divided into vibrational and rotational region. Both the Poincaré surface of section and the closed orbit theory verify the same conclusion clearly. In this paper we choose the atomic principal quantum number as n = 20. The dynamical character of the exited hydrogen atom depends sensitively on the atom-surface distance d. When d is sufficiently large, the atom-surface potential can be expressed by the traditional van der Waals force and the system is integrable. When d becomes smaller, there exists a critical value dc. For d > dc, the system is near-integrable and the motion is regular. While chaotic motion appears for d < dc, and the system tends to be non-integrable. The trajectories become unstable and the electron might be captured onto the metal surface.

关键词： Rydberg hydrogen atom, van der Waals interaction, Poincaré surface of section, closed orbit theory, chaos.

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