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921.
922.
We study the connected component of the special fiber of the Néron model of a torus split over a tamely ramified extension. It turns out to be a product of Witt vectors of finite length, explicitly calculable. We are thus able to correct a result presented in Kunyavskii and Sansuc (C. R. Acad. Sci. Paris, Ser. I 324 (1997) 307–312). To cite this article: C. Buchheim, H. Frommer, C. R. Acad. Sci. Paris, Ser. I 338 (2004). 相似文献
923.
We investigate conditions under which cusps of pinched negative curvature can be closed as manifolds or orbifolds with nonpositive
sectional curvature. We show that all cusps of complex hyperbolic type can be closed in this way whereas cusps of quaternionic
or Cayley hyperbolic type cannot be closed. For cusps of real hyperbolic type we derive necessary and sufficient closing conditions.
In this context we prove that a noncompact finite volume quotient of a rank one symmetric space can be approximated in the
Gromov Hausdorff topology by closed orbifolds with nonpositive curvature if and only if it is real or complex hyperbolic.
Using cusp closing methods we obtain new examples of real analytic manifolds of nonpositive sectional curvature and rank one
containing flats. By the same methods we get an explicit resolution of the singularities in the Baily–Borel resp.Siu–Yau compactification
of finite volume quotients of the complex hyperbolic space.
Oblatum 2-IX-1994 & 7-VIII-1995 相似文献
924.
925.
926.
927.
We present a cut and project formalism based on measures and continuous weight functions of sufficiently fast decay. The emerging
measures are strongly almost periodic. The corresponding dynamical systems are compact groups and homomorphic images of the
underlying torus. In particular, they are strictly ergodic with pure point spectrum and continuous eigenfunctions. Their diffraction
can be calculated explicitly. Our results cover and extend corresponding earlier results on dense Dirac combs and continuous
weight functions with compact support. They also mark a clear difference in terms of factor maps between the case of continuous
and non-continuous weight functions.
Dedicated to Robert V. Moody on the occasion of his 65th birthday 相似文献
928.
929.
L F Zerilli D M Edwards A Borghi G G Gallo E Selva M Denaro G C Lancini 《Rapid communications in mass spectrometry : RCM》1992,6(2):109-114
Structures of the fatty acid residues characterizing the various components of A40926 were determined by gas chromatography/mass spectrometry on the methyl esters obtained by methanolysis of the complex. The results confirm the residues previously assigned to Factor A (n-undecanoic acid) and B (10-methyl-undecanoic acid) and establish the residues of Factor A1 (9-methyl-decanoic acid), B1 (n-dodecanoic acid), RS1 (8-methyl-nonanoic acid), RS2 (n-decanoic acid), and RS3 (n-tridecanoic acid). As the Actinomadura species contain in their mycelia large quantities of C15-C17 fatty acid residues as membrane phospholipids, these mycelia were saponified and the fatty acids obtained were analyzed as above. There is a close correlation between the fatty acid content of A40926 complex and that of the longer homologues in the producer mycelia. 相似文献
930.
Tom Scarvie Nord Andresen Ken Baptiste John Byrd Mike Chin Michael C. Martin Wayne R. McKinney Christoph Steier 《Infrared Physics & Technology》2004,45(5-6):403-408
The quality of infrared microscopy and spectroscopy data collected at synchrotron based sources is strongly dependent on signal-to-noise. We have successfully identified and suppressed several noise sources affecting beamlines 1.4.2, 1.4.3, and 1.4.4 at the advanced light source (ALS), resulting in a significant increase in the quality of FTIR spectra obtained. In this paper, we present our methods of noise source analysis, the negative effect of noise on the infrared beam quality, and the techniques used to reduce the noise. These include reducing the phase noise in the storage ring radio-frequency (RF) system, installing an active mirror feedback system, analyzing and changing physical mounts to better isolate portions of the beamline optics from low-frequency environmental noise, and modifying the input signals to the main ALS RF system. We also discuss the relationship between electron beam energy oscillations at a point of dispersion and infrared beamline noise. 相似文献