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Coupled nonlinear Schrödinger (CNLS) equations with an external elliptic function potential model with high accuracy a quasi-one-dimensional interacting two-component Bose-Einstein condensate (BEC) trapped in a standing wave generated by a few laser beams. The construction of stationary solutions of the two-component CNLS equation with a periodic potential(More)
The possibility of unidirectional motion of a kink (topological soliton) of a dissipative sine-Gordon equation in the presence of ac forces with harmonic mixing (at least biharmonic) and of zero mean, is presented. The dependence of the kink mean velocity on system parameters is investigated numerically and the results are compared with a perturbation(More)
The mechanism underlying the soliton ratchet, both in absence and in presence of noise, is investigated. We show the existence of an asymmetric internal mode on the soliton profile that couples, through the damping in the system, to the soliton translational mode. Effective soliton transport is achieved when the internal mode and the external force are(More)
Experimental observation of the unidirectional motion of a topological soliton driven by a biharmonic ac force of zero mean is reported. The observation is made by measuring the current-voltage characteristics for a fluxon trapped in an annular Josephson junction that was placed into a microwave field. The dependence of the fluxon mean velocity at zero dc(More)
BACKGROUND Little information exists on the prevalence and prevention of deep vein thrombosis (DVT) and pulmonary embolism (PE) in patients admitted for acute exacerbations of chronic obstructive pulmonary disease (COPD). OBJECTIVE To review available literature, we performed a Medline search on papers published on this topic between 1966 and 2003. DATA(More)
The existence of stable solitons in two-and three-dimensional (2D and 3D) media governed by the self-focusing cubic nonlinear Schrödinger equation with a periodic potential is demonstrated by means of the variational approximation (VA) and in direct simulations. The potential stabilizes the solitons against collapse. Direct physical realizations are a(More)
In the present paper we use the Wannier function basis to construct lattice approximations of the nonlinear Schrödinger equation with a periodic potential. We show that the nonlinear Schrödinger equation with a periodic potential is equivalent to a vector lattice with long-range interactions. For the case-example of the cosine potential we study the(More)
The possibility that the sliding motion of proteins on DNA is influenced by the base sequence through a base pair reading interaction, is considered. Referring to the case of the T7 RNA-polymerase, we show that the protein should follow a noise-influenced sequence-dependent motion which deviate from the standard random walk usually assumed. The general(More)
BACKGROUND Little information is available about the prevalence of deep vein thrombosis (DVT) after discharge from cardiac surgery units and its impact on rehabilitation programs. OBJECTIVES To estimate the rate of DVT, in relation to different thromboprophylaxis strategies, in patients with a recent coronary artery bypass graft (CABG) entering cardiac(More)