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41.
42.
Yu M Driver SM Woodruff DP 《Langmuir : the ACS journal of surfaces and colloids》2005,21(16):7285-7291
Scanning tunneling microscopy (STM) has been used to investigate the structure of the ordered methanethiolate overlayer formed on Ag(111) by reaction at room temperature with dimethyl disulfide. High-resolution images show an ordered structure with three inequivalent atomic-scale protrusions within each ( radical7 x radical7)R19 degrees surface unit mesh which can be reconciled with methanethiolate species on a regular lateral submesh, similar to that proposed in the multilayer ( radical7 x radical7)R19 degrees -S sulfide phase previously reported. STM imaging during dynamic dosing also provides evidence for a significant change in the outermost layer Ag atom density, consistent with a reconstructed surface model. Possible models for this reconstruction are presented and discussed in the light of available information. 相似文献
43.
44.
Summary.
For univariate functions the Kronecker theorem, stating the equivalence
between the existence of an infinite block in the table of Padé approximants
and the approximated function being rational, is well-known.
In [Lubi88] Lubinsky proved that if is not rational, then its Padé table
is normal almost everywhere: for an at most countable set of points the
Taylor series expansion of is such that it generates a non-normal
Padé table. This implies that the Padé operator is an almost always
continuous operator because it is continuous when computing a normal
Padé approximant [Wuyt81].
In this paper we generalize the above results to the case of multivariate
Padé approximation. We distinguish between two different approaches for
the definition of multivariate Padé approximants: the general order one
introduced in [Levi76, CuVe84] and the so-called homogeneous one discussed
in [Cuyt84].
Received December 19, 1994 相似文献
45.
46.
We prove results for the interlacing of zeros of Jacobi polynomials of the same or adjacent degree as one or both of the parameters are shifted continuously within a certain range. Numerical examples are given to illustrate situations where interlacing fails to occur. 相似文献
47.
48.
Elgarøy Ø Lahav O Percival WJ Peacock JA Madgwick DS Bridle SL Baugh CM Baldry IK Bland-Hawthorn J Bridges T Cannon R Cole S Colless M Collins C Couch W Dalton G De Propris R Driver SP Efstathiou GP Ellis RS Frenk CS Glazebrook K Jackson C Lewis I Lumsden S Maddox S Norberg P Peterson BA Sutherland W Taylor K 《Physical review letters》2002,89(6):061301
We constrain f(nu) identical with Omega(nu)/Omega(m), the fractional contribution of neutrinos to the total mass density in the Universe, by comparing the power spectrum of fluctuations derived from the 2 Degree Field Galaxy Redshift Survey with power spectra for models with four components: baryons, cold dark matter, massive neutrinos, and a cosmological constant. Adding constraints from independent cosmological probes we find f(nu)<0.13 (at 95% confidence) for a prior of 0.1相似文献
49.
Kathy Driver Helmut Prodinger Carsten Schneider J. A. C. Weideman 《The Ramanujan Journal》2006,11(2):139-158
Combinatorial identities that were needed in [25] are proved, mostly with C. Schneider’s computer algebra package Sigma. The form of the Padé approximation of the logarithm of arbitrary order is stated as a conjecture.
2000 Mathematics Subject Classification Primary—41A21, 05A19, 33F10
Supported by NRF-grant 2047226.
Supported by NRF-grant 2053748.
Supported by the Austrian Academy of Sciences, by the John Knopfmacher Research Centre for Applicable Analysis and Number
Theory, and by the SFB-grant F1305 and the grant P16613-N12 of the Austrian FWF.
Supported by NRF-grant 2053756. 相似文献
50.
We study the existence of “Lp-type” gradient estimates for the heat kernel of the natural hypoelliptic “Laplacian” on the real three-dimensional Heisenberg Lie group. Using Malliavin calculus methods, we verify that these estimates hold in the case p>1. The gradient estimate for p=2 implies a corresponding Poincaré inequality for the heat kernel. The gradient estimate for p=1 is still open; if proved, this estimate would imply a logarithmic Sobolev inequality for the heat kernel. 相似文献