The generation of instability in inviscid, non-di usive geophysical ows is generically caused by a resonance between two wave modes. The weakly nonlinear unfolding of this situation is described in the long-wave regime, using a particular two-layer quasi-geostrophic model as an illustrative example. The outcome is a system of two coupled Korteweg-de Vries equations. This system contains a very ...

We discuss the nature of polaron excitations in two models of current interest in the study of quasi-one-dimensional materials: the coupled electron-phonon and molecularcrystal models. Using for definiteness parameters appropriate to trans-(CH)„, we show that, although qualitatively very similar, the two polarons differ quantitatively in many respects. We then consider the very weakly bound pol...

Three-dimensional magnetic ordering transitions are studied theoretically in strongly anisotropic quantum magnets. An external magnetic field can drive quasi-one-dimensional subsystems with a spin gap into a gapless regime, thus inducing long-range three-dimensional magnetic ordering due to weak residual magnetic coupling between the subsystems. Compounds with higher spin degrees of freedom, su...

We note that every finite or infinite dimensional real-analytic Hamiltonian system with a quasi-periodic invariant KAM torus of finite dimension d ≥ 2 can be perturbed in such a way that the new real-analytic Hamiltonian system has a weakly mixing invariant torus of the same dimension.

The energy gain in laser wakefield acceleration is ultimately limited by dephasing, occurring when accelerated electrons outrun the accelerating phase of the wakefield. We apply quasi-phase-matching, enabled by axially modulated plasma channels, to overcome this limitation. Theory and simulations are presented showing that weakly relativistic laser intensities can drive significant electron ene...

This paper defines multiset-valued linear index grammar and unordered vector grammar with dominance links. The former models certain uses of multiset-valued feature structures in unification-based formalisms , while the latter is motivated by word order variation and by "quasi-trees", a generalization of trees. The two formalisms are weakly equivalent, and an important subset is at most context...

The main features of the recently found classically stable quasi-topological membranes and strings in generic, topologically trivial and weakly coupled two-Higgs extensions of the standard model are briefly reviewed. A variety of localized solutions in the same model are also presented.

We have already introduced upper and lower (weakly) quasi continuous fuzzy multifunctions in [3] ([3]). In [8], Malakar introduced fuzzy θ-continuous multifunctions. Again Mukherjee and Malakar have introduced fuzzy almost continuous multifunctions [9]. In this paper we have established a mutual relationships among these fuzzy multifunctions. AMS Subject Classification: 54A40, 54C99

In the paper we provide construction of a coincidence degree being homotopy invariant detecting existence solutions equations or inclusions form $Ax\in F(x)$, $x\in U$, where $A\colon D(A)\multimap E$ is an $m$-accretive operator in Banach space $ E$, $F\colon K\multimap weakly upper semicontinuous set-valued map constrained to open subset $U$ closed set $K\subset E$. Two different approaches w...