In a previous paper wave propagation was studied according to a sixth-order partial differential equation involving a complex mass M. The corresponding Yang-Feldman integral equations (indicated as SM-YF-equations), were formulated using modified Green's functions GMR(x) and GMA(x), which then...

The variational principles introduced by Kadanoff et al. in the renormalization theory are analyzed. It is shown that the values for the specific heat critical exponent α which can be found by a variational method are restricted to α 0 or α = 1 (first order transition). The reason is the...

The Korteweg-de Vries-Burgers equation (KdV-B) is studied analytically and numerically for weak dissipation in the nonstationary case (self-similar solutions). Starting the analytical study from the system (S) of two kinetic equations equivalent to KdV-B equation in the exact adiabatic...

A new method of treating open systems is presented. The normal treatment using the generalized master equation with the projection of Argyres and Kelley is meaningful only if the state of the reservoir never deviates appreciably from the reference state which appears in the projection....

The magnetic properties of the one-component plasma, in three and two dimensions, are studied in the nearly classical case. Since magnetism is an essentially quantum effect, Planck's constant ℏ can be used as a small parameter. A generalized Wigner-Kirkwood expansion in powers of ℏ2 is...

An equivalent Hamiltonian method for the analysis of isotropic antiferromagnets is proposed. The Hamiltonian does not contain the terms corresponding to the processes of non-conservation of spin waves and gives the possibility to perform the calculations with a limited and controlled error. The...

Nonlinear Kirkwood-Salsburg equations which are parametrized by the density ϱ are derived from the linear ones by elimination of the activity z. Upper bounds on ϱ are derived below which the solution of these equations is unique. Narrow upper and lower bounds on z(ϱ) are obtained as well as...

The 3-dimensional planar rotator (PR) model with short-range interaction is studied in the “harmonic” approximation where spin wave and vortex loop (VL) system decouple. The phase transition (PT) occuring in the PR-model is studied via the correlation and stability properties of the...

The constant-coupling approximation is extended to an antiferromagnetic spin-12 system with two distinct anisotropic exchange interactions. The thermodynamic properties such as the transition temperature, magnetization, susceptibility and specific heat are discussed for three special cases: (i)...

A quantum-statistical theory of chemical kinetics is presented which takes into account the non-ideality of composite particles (bound states). For the time evolution of the chemical composition operators ϱ(a∣t) a generalized Waldmann-Snider equation is obtained. The general treatment is...