The energy transport by the propagation of sound waves in wave guides with a moving medium

The problem of the propagation of sound waves radiated by a source in a fluid moving with subsonic velocity between two parallel walls or inside a cylindrical tube is considered in [2], The most interesting thing of this problem is that waves may occur with constant amplitude coming from infinity. This article gives the calculation of the energy transport in the wave guides.\ud \ud It is shown that it is not possible to gain energy from infinity

Iterative solution of a discrete axially symmetric potential problem

The Dirichlet problem for the axially symmetric potential equation in a cylindrical domain is discretized by means of a five-point difference approximation. The resulting difference equation is solved by point or line iterative methods. The rate of convergence of these methods is determined by the spectral radius of the underlying point or line Jacobi matrix. An asymptotic approximation for this spectral radius, valid for small mesh size, is derived

Correction of flotation coefficients, derived from ultracentrifugation, for pressure and concentration

Flotation coefficients are usually determined from data obtained under high pressure (cell bottom) conditions. A power series expansion is proposed for correction to atmospheric pressure (meniscus) conditions. The same expansion may be applied to the concentration correction of flotation coefficients

X-ray response of tunnel junctions with a trapping layer

The use of trapping layers in superconductive tunnel junctions may drastically improve their functioning as X-ray detectors. Information about these trapping layers can be obtained from I/V-curves and X-ray spectra. The application of a magnetic field causes a substantial reduction of the bandgap in the trapping layer

P19-25. A vaccine model to prevent the depletion of uninfected bystander CD4 cells during HIV infection

International audiencen.

Economics of education research: a review and future prospects

In this paper we offer an appraisal of the economics of education research area, charting its history as a field and discussing the ways in which economists have contributed both to education research and to education policy-making. In particular, we highlight the theoretical and methodological contributions that economists have made to the field of education during the last 50 years. Despite the success of the economics of education as a field of inquiry, we argue that some of the contributions made by economists could be limited if the economics of education is seen as quite distinct from the other disciplines working in the field of education. In these areas of common interest, economists need to work side by side with the other major disciplines in the field of education if their contribution to the field is to be maximised, particularly in terms of applying improved methodology. We conclude that the study of education acquisition and its economic and social impact in the economics of education research area is very likely to remain a fertile research ground. Acknowledgement