1,721,352 research outputs found
Restructuration de la production et travail dans les entreprises installées au Brésil
No full textSalerno Mario. Restructuration de la production et travail dans les entreprises installées au Brésil. In: Tiers-Monde, tome 39, n°154, 1998. Les transformations du travail (Amérique latine, Asie) sous la direction de Helena Hirata, Bruno Lautier et Pierre Salama. pp. 305-328
Macroscopic quantum bound states and Josephson effect in Bose-Einstein condensates in optical lattices
No full textLocalized ground states of the periodic Gross-Pitaevskii equation (GPE) are considered in the framework of a quantum linear Schrodinger equation with an effective potential determined in a self-consistent manner. We show that, depending on whether the interaction among the atoms is attractive or repulsive, bound states of the linear self-consistent problem are formed in the forbidden zones of the linear spectrum below or above the energy bands, respectively. These eigenstates are found to be exact soliton solutions of the GPE. More complicated solutions of the GPE can be constructed by taking linear combinations of eigenstates as effective potentials in the self-consistent approach. In particular, we discuss bound-state wavefunctions that describe Bose-Einstein condensate (BEC) Josephson junctions. These bound states consist of two localized weakly interacting condensates that exhibit, in the interaction region, matter oscillations that are governed by the phase difference between the wavefunctions of the two condensates
DYNAMIC PROPERTIES OF DNA PROMOTERS
No full textDynamical properties of DNA promoters A1, A3 and D of the T7 family are investigated. A connection between base sequences, dynamics, and functioning of these promoters is found. This suggests a dynamical mechanism for genetic activation
Exact analytical solutions for the Hubbard model with unconstrained hopping
No full textA general method to construct basis functions for fermionic systems which possess the U(1), SU(2) and S-f symmetry is presented. We use this method to derive the analytical expression for the ground state energy of the Hubbard model with unconstrained hopping at half filling and for arbitrary lattice sites
DISCRETE MODEL FOR DNA-PROMOTER DYNAMICS
No full textWe introduce a discrete model for DNA that takes into account the information about specific base sequences along the double helix. We use this model to study nonlinear wave dynamics of the T7 A1 DNA promoter. As results we show the existence in the promoter of a dynamically active region in which static solitons acquire finite velocities, which contrasts with regions where solitons simply remain static. Furthermore, when they pass through this region moving solitons are accelerated, decelerated, or reflected, depending on their initial velocities. The possibility that these dynamical effects play a role in the mechanism of genetic activation is suggested
REFLECTION OF FLUXONS ON A JOSEPHSON LINE FROM A PERTURBATIVE POINT OF VIEW
No full textThe fluxon-antifluxon reflection at a passive termination of a semi-infinite Josephson line is examined in terms of an infinite perturbed line. We find that the perturbative approach provides the same results as those obtained by other authors from energetic considerations. Furthermore it permits explicit calculations of the radiation emitted from a single fluxon as it undergoes the reflection
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