The influence of music and stress on musicians’ hearing

Hearing and hearing disorders among classical and rock/jazz musicians was investigated. Pure tone audiometry was done in 140 classical and 139 rock/jazz musicians. The rock/jazz musicians answered a questionnaire concerning hearing disorders and psychosocial exposure. All results were compared to age appropriate reference materials. Hearing thresholds showed a notch configuration in both classical and rock/jazz musicians indicating the inclusion of high sound levels but an overall well-preserved hearing thresholds. Female musicians had significantly better hearing thresholds in the high-frequency area than males. Rock/jazz musicians showed slight worse hearing thresholds as compared to classical musicians. When assessing hearing disorders, a large number of rock/jazz musicians suffered from different hearing disorders (74%). Hearing loss, tinnitus and hyperacusis were the most common disorders and were significantly more frequent in comparison with different reference populations. Among classical musicians, no extended negative progress of the pure tone hearing threshold values was found in spite of the continued 16 years of musical noise exposure. In rock/jazz musicians, there was no relationships between psychosocial factors at work and hearing disorders. The rock/jazz musicians reported low stress and high degree of energy. On the average, the rock/jazz musicians reported higher control, lower stress and higher energy than a reference material of white-collar workers.     

Isolation of chlorinated fatty acid methyl esters derived from cell-culture medium and from fish lipids by using an aminopropyl solid-phase extraction column

An aminopropyl-based solid-phase extraction technique was used for isolation of chlorinated fatty acids in lipids. A range of different chlorinated fatty acids was eluted in a small volume of solvent (4 ml) and the recoveries of the different species and isomers were quantitative. Only 1% of the vastly dominating unchlorinated fatty acid methyl esters were recovered in the fractions containing the chlorinated fatty acid methyl esters. This method makes it possible to isolate and detect > or = 1 microg of a chlorinated fatty acid methyl ester in 1 g of lipid.     

A uniformly well-conditioned, unfitted Nitsche method for interface problems

A finite element method for elliptic partial differential equations that allows for discontinuities along an interface not aligned with the mesh is presented. The solution on each side of the interface is separately expanded in standard continuous, piecewise-linear functions, and jump conditions at the interface are weakly enforced using a variant of Nitsche’s method. In our method, the solutions on each side of the interface are extended to the entire domain which results in a fixed number of unknowns independent of the location of the interface. A stabilization procedure is included to ensure well-defined extensions. We prove that the method provides optimal convergence order in the energy and the L ² norms and a condition number of the system matrix that is independent of the position of the interface relative to the mesh. Numerical experiments confirm the theoretical results and demonstrate optimal convergence order also for the pointwise errors.     

Synthesis of C 2 Symmetric Potential Inhibitors of HIV-1 Protease From D-Mannitol

ABSTRACT

D-Mannitol was used as precursor for the synthesis of acyclic C ₂ symmetric potential HIV-1 protease inhibitors. The 1- and 6-hydroxy groups of D-mannitol were substituted by -NHBoc, -NHValZ, -SAr, -SOAr and -SO₂Ar and the 2-and 5-hydroxy groups were benzylated. In some products one of the central hydroxyl groups was either inverted or deoxygenated. Despite a close structural similarity to previously published inhibitors none of the products showed significant inhibitory activity against HIV-1 protease.

     

An investigation of the internal structure of shock profiles for shock capturing schemes

The theoretical understanding of discrete shock transitions obtained by shock capturing schemes is very incomplete. Previous experimental studies indicate that discrete shock transitions obtained by shock capturing schemes can be modeled by continuous functions, so called continuum shock profiles. However, the previous papers have focused on linear methods. We have experimentally studied the trajectories of discrete shock profiles in phase space for a range of different high resolution shock capturing schemes, including Riemann solver based flux limiter methods, high resolution central schemes and ENO type methods. In some cases, no continuum profiles exists. However, in these cases the point values in the shock transitions remain bounded and appear to converge toward a stable limit cycle. The possibility of such behavior was anticipated in Bultelle, Grassin and Serre, 1998, but no specific examples, or other evidence, of this behavior have previously been given. In other cases, our results indicate that continuum shock profiles exist, but are very complicated. We also study phase space orbits with regard to post shock oscillations.     

On the smallest scale for the incompressible Navier-Stokes equations

We prove that, for solutions to the two- and three-dimensional incompressible Navier-Stokes equations, the minimum scale is inversely proportional to the square root of the Reynolds number based on the kinematic viscosity and the maximum of the velocity gradients. The bounds on the velocity gradients can be obtained for two-dimensional flows, but have to be assumed in three dimensions. Numerical results in two dimensions are given which illustrate and substantiate the features of the proof. Implications of the minimum scale result, to the decay rate of the energy spectrum are discussed.Research was supported in part by the National Acronautics and Space Administration under NASA Contract No. NAS1-18107, while the second author was in residence at the Institute for Computer Applications in Science and Engineering (ICASE), NASA Langley Research Center, Hampton, VA 23665. Additional support was provided by the National Science Foundation under Grant DMS-8312264 and the Office of Naval Research under Contract N-00014-83-K-0422.     

Über Die Stabilitätsdefinition Für Differenzengleichungen Die Partielle Differentialgleichungen Approximieren

For difference equations with constant coefficients necessary and sufficient algebraic stability conditions are given for the stability definitions used by G. Forsythe and W. Wasow (A) and P. D. Lax and R. D. Richtmyer (B). The application of these conditions for difference equations with variable coefficients is considered and it is shown that the stability condition of definitionA is not sufficient for stability. The same is true with respect to the definitionB if the difference equations are not parabolic and do not approximate first order systems. Therefore another stability definition is proposed and a number of properties are discussed.     

Atomistic-continuum multiscale modelling of magnetisation dynamics at non-zero temperature

In this article, a few problems related to multiscale modelling of magnetic materials at finite temperatures and possible ways of solving these problems are discussed. The discussion is mainly centred around two established multiscale concepts: the partitioned domain and the upscaling-based methodologies. The major challenge for both multiscale methods is to capture the correct value of magnetisation length accurately, which is affected by a random temperature-dependent force. Moreover, general limitations of these multiscale techniques in application to spin systems are discussed.