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Recently, it was proved by Leedham-Green and others that with a finite number of exceptions, every p-group of coclass r is a quotient of one of only a finite number of p-adic uniserial space groups. In this paper we use that structure to demonstrate that there are only finitely many isomorphism classes of cohomology rings of 2-groups of coclass r with coefficients in any fixed field k of characteristic 2. In addition, there is experimental evidence indicating that in many cases successive quotients of the uniserial space groups have isomorphic cohomology rings. 相似文献
223.
Abstract— This article provides a brief overview of time-resolved infrared spectroscopy (TRIR) applied to the investigation of organometallic photochemistry in solution. In this context, some fundamental problems where flash photolysis TRIR techniques may provide information relevant to photochemical pathways and to certain thermal reaction mechanisms are described. Different approaches to obtaining TRIR spectral information are summarized and illustrated with specific applications. 相似文献
224.
In this paper we analyze conjugate gradient-type algorithms for solving convex quadratic programs subject only to box constraints (i.e., lower and upper bounds on the variables). Programs of this type, which we denote by BQP, play an important role in many optimization models and algorithms. We propose a new class of finite algorithms based on a nonfinite heuristic for solving a large, sparse BQP. The numerical results suggest that these algorithms are competitive with Dembo and Tulowitzski's (1983) CRGP algorithm in general, and perform better than CRGP for problems that have a low percentage of free variables at optimality, and for problems with only nonnegativity constraints. 相似文献
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Elaine Smith Margaretta Taylor Maria Mendoza Jon Lemke Henry Hoffman 《Journal of voice》1998,12(4):551-558
Patients diagnosed with nodules (NO = 40) in a large university hospital clinic and an age-stratum matched nondiseased group (ND = 200) described adverse outcomes of vocal impairment on work and work-related communications. NOs were significantly more likely than NDs to report symptoms of hoarseness (73% vs. 26%), high-note difficulty (70% vs. 20%), difficulty speaking with a lower voice (53% vs. 13%) and a tired voice (50% vs. 10%), and their greatest source of physical discomfort was associated with scratchiness (61% vs. 3%). The average number of symptoms was four in NOs and less than one in NDs. Nodule patients were most concerned about the effects their voice problem would have on their future career (78% vs. 24%) and 49% of NOS reported their voice problem had an adverse work effect in the past compared with 4% of NDs. Having a voice condition limited current job performance in 39% of the NO group but only in 2% of the ND group. The results suggest that a diagnosis of nodules plays a major role in disrupting careers and work activities and that available educational programs and additional research are needed for improving their functional ability and preventing adverse outcomes in the lives of individuals with voice disorders. 相似文献
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Jon Aaronson 《Israel Journal of Mathematics》1985,51(1-2):151-162
We prove (Baire) category theorems for ergodic multiplier properties stronger than weak mixing, and weaker than mild mixing. 相似文献
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Jon Aaronson 《Proceedings Mathematical Sciences》1994,104(2):413-419
We show that the Cauchy random walk on the line, and the Gaussian random walk on the plane are similar as infinite measure
preserving transformations. 相似文献