Continuous Markovian model for Lévy random walks with superdiffusive and superballistic regimes

We consider a previously devised model describing Lévy random walks [I. Lubashevsky, R. Friedrich, A. Heuer, Phys. Rev. E 79, 011110 (2009); I. Lubashevsky, R. Friedrich, A. Heuer, Phys. Rev. E 80, 031148 (2009)]. It is demonstrated numerically that the given model describes Lévy random walks with superdiffusive, ballistic, as well as superballistic dynamics. Previously only the superdiffusive regime has been analyzed. In this model the walker velocity is governed by a nonlinear Langevin equation. Analyzing the crossover from small to large time scales we find the time scales on which the velocity correlations decay and the walker motion essentially exhibits Lévy statistics. Our analysis is based on the analysis of the geometric means of walker displacements and allows us to tackle probability density functions with power-law tails and, correspondingly, divergent moments.     

Charge partition probabilities in the32S+27Al reaction at 37.5 MeV/nucleon analysed using the boltzmann distribution

We apply the Boltzmann distribution to charge partition probabilities measured with the AMPHORA multidetector in the reaction³²S+²⁷Al at 37.5 MeV/nucleon. Approximate corrections to the data for preequilibrium emission are made and modifications to the basic formalism due to detection efficiency and evaporation are treated explicitly. The data are well reproduced with a temperature of 5.0 MeV and a freeze-out volume which corresponds to densities which are 20 times smaller than normal density.     

Respiratory and glottal efficiency measures in normal classically trained singers

Respiratory and glottal efficiency measures were collected from a pool of 40 classically trained singers with normal larynges. All singers had ?3 years of formal classical voice training and were active professional solo classical singers. Mean flow rates were obtained from all subjects to assess glottal efficiency. Additionally, maximum phonation times and phonation quotients were obtained from a subset of the singers. Pulmonary function test data on forced expiratory volume, forced vital capacity, and forced expiratory flow were obtained for all subjects. Results were compared with published normal values, not specifically derived from trained singers, used commonly in voice laboratoires. Differences were found, suggesting the need for separate normative data to be used for evaluation of the vocal athlete.     

Effect of topological asymmetry on the electrophoretic mobility of branched DNA structures with and without single-base mismatches

The electrophoretic mobility of three-arm star DNA structures with varying degrees of branch length asymmetry has been investigated in polyacrylamide (PAA) hydrogels. We report the effect of single-base mismatches, adjacent to the branch point, on the mobility of branched DNA with three different arm lengths. Branched DNA structures were formed using wild-type and mutated fragments of the p53 tumor suppressor gene, which is believed to play an important role in cancer development. Branching was directed at the site of several previously characterized mutations in exon 7 of p53. At a given gel concentration, the mobility of branched DNA with fully complementary base pairing is found to increase as the degree of branch length asymmetry is increased. Ferguson analysis of the gel electrophoresis data leads to a retardation coefficient that is strongly dependent on topology. This finding can be explained in terms of a minimum molecular cross-section for each molecule. Specifically, we show that structures with the smallest molecular cross-section can access more pores in the gel, which leads to higher mobility. Our results can also be understood by considering the rotational diffusivity of branched DNA. Asymmetric DNA stars with higher calculated rotational diffusivities also have higher mobilities. When a mutated base is present in junctions with low degrees of branch length asymmetry, adjacent to the branch point, the mobility increases in comparison to the fully complementary molecules. The reason for this increased mobility is unclear, here, we propose that the mismatched base introduces additional flexibility to the arm containing the mutation leading to higher conformational freedom and enhanced mobility in gels. When a mismatched base is present in junctions with high degrees of branch length asymmetry, the opposite result is obtained. Here, the mutated species has a lower mobility. This result is argued to arise from incomplete hybridization and/or frayed ends. Finally, we have shown that by using two of the branch point oligonucleotides as probe molecules, mutations known to occur at specific sites can be detected through the mobility shift. If the sequences of the probe chains are changed in a controlled manner, the location and base of the mutant can also be determined.     

Exponential convergence of the hp-version for the boundary element method on open surfaces

Summary. We analyze the boundary element Galerkin method for weakly singular and hypersingular integral equations of the first kind on open surfaces. We show that the hp-version of the Galerkin method with geometrically refined meshes converges exponentially fast for both integral equations. The proof of this fast convergence is based on the special structure of the solutions of the integral equations which possess specific singularities at the corners and the edges of the surface. We show that these singularities can be efficiently approximated by piecewise tensor products of splines of different degrees on geometrically graded meshes. Numerical experiments supporting these results are presented. Received December 19, 1996 / Revised version received September 24, 1997 / Published online August 19, 1999