We explore the dynamical stabilities of a quasi-one dimensional (1D) Bose-Einstein condensate (BEC) consisting of fixed N atoms with time-independent external potential. For the stationary states with zero flow density the general solution of the perturbed time evolution equation is constructed, and the stability criterions concerning the initial conditions and system parameters are established...

Given an effectively parameterized family of canonically polarized manifolds the Kähler-Einstein metrics on the fibers induce a hermitian metric on the relative canonical bundle. We use a global elliptic equation to show that this metric is strictly positive. For degenerating families we obtain a singular hermitian metric. Applications concern the curvature of the classical and generalized Weil...

X iv :s ol vin t/9 81 20 31 v1 2 9 D ec 1 99 8 Twoand Many-Dimensional Quasi-Exactly Solvable Models With An Inhomogeneous Magnetic Field O. B. Zaslavskii Department of Physics, Kharkov State University, Svobody Sq.4, Kharkov 310077, Ukraine E-mail: [email protected] Let group generators having finite-dimensional representation be realized as Hermitian linear differential operators without inhomo...

Biased diffusive transport of Brownian particles through irregularly shaped, narrow confining quasi-one-dimensional structures is investigated. The complexity of the higher dimensional diffusive dynamics is reduced by means of the so-called Fick-Jacobs approximation, yielding an effective one-dimensional stochastic dynamics. Accordingly, the elimination of transverse, equilibrated degrees of fr...

the only justification for the einstein velocity addition law appeared to be its empirical adequacy, so that the intrinsic beauty and harmony in einstein addition remained for a long time a mystery to be conquered. accordingly, the aim of this expository article is to present (i) the einstein relativistic vector addition, (ii) the resulting einstein scalar multiplication, (iii) the einstein rel...

There is a construction of random subsets of Z in which almost every subset is Sidon (this was first done by Katznelson). More is true: almost every subset is the finite union of quasi-independent sets. Also, if every Sidon subset of Z\{0} is the finite union of quasi-independent sets, then the required number of quasi-independent sets is bounded by a function of the Sidon constant. Analogs of ...

A minimal dynamical system (X,T ) is called quasi-Bohr if it is a nontrivial equicontinuous extension of a proximal system. We show that if (X,T ) is a minimal dynamical system which is not weakly mixing then some minimal proximal extension of (X, T ) admits a nontrivial quasi-Bohr factor. (In terms of Ellis groups the corresponding statement is: AG′ = G implies weak mixing.) The converse does ...

Sufficient and necessary conditions are provided on warped product manifolds their base fiber for a vector field $$\varphi _{j}$$ to be \left( \mathrm {Ric}\right) $$ -vector , that is, $$\nabla _{i}\varphi _{j}=\mu R_{ij}$$ where $$R_{ij}$$ is the Ricci tensor of M \mu scalar. Two space-times admitting fields considered. Lorentzian quasi-Einstein time-like {Ric} \right) shown either simple or ...

The relativity to the measuring device in quantum theory, i.e. the covariance of local dynamical variables relative transformations to moving quantum reference frame in Hilbert space, may be achieved only by the rejection of super-selection rule. In order to avoid the subjective nuance, I emphasis that the notion of “measurement” here, is nothing but the covariant differentiation procedure in t...