Exact Moving and Stationary Solutions of a Generalized Discrete Nonlinear Schrodinger Equation

We obtain exact moving and stationary, spatially periodic and localized solutions of a generalized discrete nonlinear Schr\"odinger equation. More specifically, we find two different moving periodic wave solutions and a localized moving pulse solution. We also address the problem of finding exact stationary solutions and, for a particular case of the model when stationary solutions can be expressed through the Jacobi elliptic functions, we present a two-point map from which all possible stationary solutions can be found. Numerically we demonstrate the generic stability of the stationary pulse solutions and also the robustness of moving pulses in long-term dynamics.Comment: 22 pages, 7 figures, to appear in J. Phys.

Random anisotropy disorder in superfluid 3He-A in aerogel

The anisotropic superfluid 3He-A in aerogel provides an interesting example of a system with continuous symmetry in the presence of random anisotropy disorder. Recent NMR experiments allow us to discuss two regimes of the orientational disorder, which have different NMR properties. One of them, the (s)-state, is identified as the pure Larkin-Imry-Ma state. The structure of another state, the (f)-state, is not very clear: probably it is the Larkin-Imry-Ma state contaminated by the network of the topological defects pinned by aerogel.Comment: JETP Lett. style, 6 pages, no figures, discussion extended, references added, version to be published in JETP Letter

AC Josephson properties of phase slip lines in wide tin films

Current steps in the current-voltage characteristics of wide superconducting Sn films exposed to a microwave irradiation were observed in the resistive state with phase slip lines. The behaviour of the magnitude of the steps on the applied irradiation power was found to be similar to that for the current steps in narrow superconducting channels with phase slip centers and, to some extent, for the Shapiro steps in Josephson junctions. This provides evidence for the Josephson properties of the phase slip lines in wide superconducting films and supports the assumption about similarity between the processes of phase slip in wide and narrow films.Comment: 7 pages, 2 figures, to be published in Supercond. Sci. Techno