It is shown that a scheme for the approximate calculation of the dispersion relations suggested by Gershon and Oppenheim seems to account for the sound speed dispersion reasonably well but poorly describes the wave vector dependence of the damping.

A polymer molecule in solution is treated as a porous sphere with a spherically symmetric permeability distribution. Solvent motion in and around this sphere is described by the Debije- Brinkman equation (Navier-Stokes equation and Darcy equation combined). The model allows a straightforward...

The sum over paths for a generalized Wiener diffusion process has been presented in a previous paper on the basis of the concept of time-local gaussian processes. This well-defined functional sum leads to a functional integral for the probability of passing from an initial state to some final...

We study thermal fluctuations in a conducting medium which may be spatially non-uniform and anisotropic. The fluctuation spectra for charge and current density, and for the electromagnetic fields, are expressed in terms of the basic propagators of the macroscopic equations. The theory is based...

There are equations, like the KDV equation, of which the solutions behave like conservative systems although the equation is of first order in time. It is shown how equations of this kind can originate by a direct-product like process of fusion of two canonical conjugate variables. Conversely,...

For systems of interacting Brownian particles a Fokker-Planck equation is derived for the probability distribution function of the concentration fluctuations, using assumption of a Gaussian static distribution function. The drift- and the diffusion term are determined by static correlation...

A new approximate solution of the stochastic process associated to the laser transient radiation is proposed. It is shown that, by means of the classical equation of motion, it is possible to introduce a non-linear time-dependent mapping between the original stochastic process and a new process...

The thermodynamic properties of a generalized Dicke model including (i) spatial variation of the electromagnetic field, (ii) classical Debye vibrations of the atoms around their equilibrium positions, are investigated in the thermodynamic limit in an exact fashion. Contrary to the ordinary case...

The thermal conductivity of gaseous nitrogen, methane and carbon dioxide has been measured at room temperature and at pressures up to 35 MPa in the cases of nitrogen and methane and up to 5 MPa in the case of carbon dioxide. A transient hot-wire technique was used, which has been described...