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101.
We give cogenerators for the categories of convex (= finitely superconvex), finitely positively convex, and absolute convex (= finitely totally convex) spaces introduced by Pumplün and Röhrl.Dedicated to our academic teacher Dieter Pumplün on the occasion of his sixtieth birthday. 相似文献
102.
Enquist H Navirian H Nüske R von Korff Schmising C Jurgilaitis A Herzog M Bargheer M Sondhauss P Larsson J 《Optics letters》2010,35(19):3219-3221
We have developed and characterized a hard x-ray accumulating streak camera that achieves subpicosecond time resolution by using single-photon counting. A high repetition rate of 2 kHz was achieved by use of a readout camera with built-in image processing capabilities. The effects of sweep jitter were removed by using a UV timing reference. The use of single-photon counting allows the camera to reach a high quantum efficiency by not limiting the divergence of the photoelectrons. 相似文献
103.
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105.
Oxygen and carbon isotopic compositions of tree ring cellulose (δ13Ccell and δ18Ocell) were measured for pines growing at four sites in east Germany. Three sites differed markedly in soil water availability within a short distance and the fourth site served as a reference. The choice of the sites was guided by the desire to detect effects of air pollution on the long-term trend of isotopic compositions and to examine the influence of soil water availability on the relationship between the carbon and oxygen isotope ratios. Locations in east Germany are particularly well suited for the study of pollution effects because there was a steady increase in environmental contamination until the German Reunification in 1990, followed by a sharp decline due to the implementation of stricter environmental standards. The long-term trend of δ13Ccell showed an extraordinary increase in the period 1945–1990 and a rapid decrease after 1990, whereas δ18Ocell remained nearly constant. The increase of δ13Ccell is explained by secondary fractionation caused by phytotoxicity of SO2. Two effects are mainly responsible for the secondary fractionation under SO2 exposure: increase of dark respiration, and changes in photosynthate allocation and partitioning. Both effects do not influence δ18Ocell. Furthermore, a significant positive correlation between the year-to-year variations of carbon and oxygen isotope ratios (δ13Cresid and δ18Oresid) has been found for all sites. The slopes of the relationship between δ13Cresid and δ18Oresid differ insignificantly. It is concluded that this relationship is not influenced by soil water availability but by climatic variables. 相似文献
106.
107.
Ralf Kaiser 《Mathematical Methods in the Applied Sciences》2012,35(11):1241-1255
In the framework of magnetohydrodynamics, the generation of magnetic fields by the prescribed motion of a liquid conductor in a bounded region is described by the induction equation, a linear system of parabolic equations for the magnetic field components. Outside G, the solution matches continuously to some harmonic field that vanishes at spatial infinity. The kinematic dynamo problem seeks to identify those motions, which lead to nondecaying (in time) solutions of this evolution problem. In this paper, the existence problem of classical (decaying or not) solutions of the evolution problem is considered for the case that G is a ball and for sufficiently regular data. The existence proof is based on the poloidal/toroidal representation of solenoidal fields in spherical domains and on the construction of appropriate basis functions for a Galerkin procedure. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
108.
Rainer Koch Ralf Becker 《Journal of Quantitative Spectroscopy & Radiative Transfer》2004,84(4):423-435
After reviewing the presently available quadrature schemes for the discrete ordinates method, the accuracy of different schemes is analyzed and evaluated. It is shown from a comprehensive error analysis that the moment conditions have to satisfied not only for the principal coordinates directions, as it is mostly carried out, but for any arbitrary test direction. Among the schemes with approximately 50 discrete ordinates the DCT-020-2468 quadrature was found to give the best accuracy. The highest accuracy among all schemes is achieved by the LC-11 quadrature which requires 96 discrete ordinates. This scheme is rarely used up to date and deserves more attention for high accuracy predictions. 相似文献
109.
The 4p photoelectron spectra of metallic Nb, Mo, Ru and Rh have been recorded. By use of a deconvolution procedure it is shown that the 4p spin-orbit component has a linewidth which significantly exceeds that of the 4p component. This suggests that N2N3N45 super Coster Kronig processes give a considerable contribution to the decay rata of the 4p hole state. 相似文献
110.
Edgar Baumeister Heinz Oberhammer Heinar Schmidt Ralf Steudel 《Heteroatom Chemistry》1991,2(6):633-641
The vapor phase structure of (CH3O)2S [1] has been investigated by electron diffraction and ab initio MO calculations, which both result in a C2 symmetry for the most stable geometry, the Cs conformer being less stable by about 12 kJ/mol. The torsional barrier for rotation about one SO bond was calculated as 37 kJ/mol (trans barrier). The geometrical parameters (electron diffraction) of the C2 conformer are: dSO = 162.5(2), dCO = 142.6(3), dCH = 110.5(7) pm angles OSO = 103(1)°, SOC = 115.9(4)°, HCH = 109(1)°, torsional angle COSO = 84(3)°. Geometrical data calculated with 6-31G* basis set agree well with the diffraction data; calculated dipole moments 1.1 D (C2) and 3.3 D (Cs). The infrared spectrum of gaseous (CH3O)2S and the Raman spectra of liquid and solid (CH3O)2S are reported and have been almost fully assigned to the 27 fundamental vibrations. 相似文献