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61.
We will prove a result concerning the inclusion of non-trivial invariant ideals inside non-trivial ideals of a twisted crossed
product. We will also give results concerning the primeness and simplicity of crossed products of twisted actions of locally
compact groups on -algebras.
Received: 25 January 2002; in final form: 22 May 2002/Published online: 2 December 2002
This work is partially supported by Hong Kong RGC Direct Grant. 相似文献
62.
We obtain a lower bound on the number of prime divisors of integers whose g-ary expansion contains a fixed number of nonzero digits.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
63.
64.
I. P. Kuranova K. M. Polyakov E. A. Smirnova W. E. Höhne V. S. Lamzin R. Meijer 《Crystallography Reports》2003,48(6):953-958
Crystals of Saccharomyces cerevisiae inorganic pyrophosphatase suitable for X-ray diffraction study were grown by cocrystallization of the enzyme with cobalt chloride and imidodiphosphate. Saccharomyces cerevisiae is a metal-dependent enzyme which catalyzes hydrolysis of inorganic pyrophosphate to orthophosphate. The three-dimensional structure of this enzyme was solved by the molecular-replacement method and refined at 1.8 Å resolution to an R factor of 19.5%. Cobalt and phosphate ions were revealed in the active centers of both identical subunits (A and B) of the pyrophosphatase molecule. In subunit B, a water molecule was found between two cobalt ions. It is believed that this water molecule acts as an attacking nucleophile in the enzymatic cleavage of the pyrophosphate bond. It was demonstrated that cobalt ions and a phosphate group occupy only part of the potential binding sites (two chemically identical and crystallographically independent subunits have different binding sites). The arrangement of ligands and the structure of the nucleophile-binding site are discussed in relation to the mechanism of action of the enzyme and the nature of the metal activator. 相似文献
65.
Harish C. Bahl Stanley Zionts 《The Journal of the Operational Research Society》1987,38(12):1141-1148
Scheduling the production of several items requires the determination of production quantities in different periods in the presence of resource constraints. Several approximate and heuristic algorithms have been proposed to solve this problem. However, no method for finding an optimal solution has as yet been developed. It is shown that the problem may be solved advantageously using Benders' decomposition. The subproblem in Benders' decomposition is shown to be a transportation problem, and some strategies for solving the master problem are indicated. The paper concludes with a sample problem demonstrating the application of the method. 相似文献
66.
67.
68.
69.
A generalization of strong regularity around a vertex subset C of a graph Γ, which makes sense even if Γis non-regular, is studied. Such a structure appears, together with a kind of distance-regularity around C , when an spectral bound concerning the so-called predistance polynomial of C is attained. As a main consequence of these results, it is shown that a regular (connected) graph Γwith d + 1 distinct eigenvalues is distance-regular, and its distance- d graph Γ d is strongly regular with parameters a = c , if and only if the number of vertices at distance d from each vertex satisfies an expression which depends only on the order of Γand the different eigenvalues of Γ. 相似文献
70.
D. Citterio Stefan Rásonyi Ursula E. Spichiger 《Fresenius' Journal of Analytical Chemistry》1996,354(7-8):836-840
New chromoionophores have been developed, focused on NIR applications so that optode membranes may be used in monolithically integrated optical sensors. The wavelength of maximum absorbance has been estimated for a new model compound by the Pariser-Parr-Pople (PPP) method. Several cyanine type dyes have been tested as membrane chromoionophores. Membrane composition has been altered to overcome solubility problems. In this way, simple pH-sensitive optode membranes have been produced. 相似文献