1,721,143 research outputs found
Signal processing by means of noise
No full textNoisy integrate-and-fire neurons encode periodic signals best at a preferred noise-frequency combination. We show that the preferred frequency, optimum noise and optimum signal-to-noise ratio are linearly related to the signal AC amplitude with the signal DC amplitude serving as tuning parameter. We argue that this may facilitate selective signal processing in neuronal networks. (C) 2001 Elsevier Science B.V. All rights reserved
Spreading and localization of wavepackets in disordered wires in a magnetic field
No full textWe study the localization properties of wavepackets in disordered wires in a magnetic field. A formula for the steady-state wave function at the crossover regime from preserved to broken time-reversal symmetry is proposed, which is in excellent agreement with our numerical data. In contrast to a recent supersymmetry approach the extracted asymptotic decay rate of the steady state changes smoothly in the crossover regime. Finally, we investigate fluctuation properties around the steady state and find a scaling for the variance of the wavepacket which also shows a smooth transition due to the magnetic field
Taming chaos by impurities in two-dimensional oscillates arrays
No full textThe effect of impurities in a two-dimensional lattice of coupled nonlinear chaotic oscillators and their ability to control the dynamical behavior of the system are studied. We show that a single impurity can produce synchronized spatiotemporal patterns, even though all oscillators and the impurity are chaotic when uncoupled. When a small number of impurities is arranged in a way, that the lattice is divided into two disjoint parts, synchronization is enforced even for small coupling. The synchronization is not affected as the size of the lattice increases, although the impurity concentration tends to zero
Particle dispersion on rapidly folding random heteropolymers
No full textWe investigate the dynamics of a particle moving randomly along a disordered heteropolymer subjected to rapid conformational changes which induce superdiffusive motion in chemical coordinates. We study the antagonistic interplay between the enhanced diffusion and the quenched disorder. The dispersion speed exhibits universal behavior independent of the folding statistics. On the other hand it is strongly affected by the structure of the disordered potential. The results may serve as a reference point for a number of translocation phenomena observed in biological cells, such as protein dynamics on DNA strands
Statistical properties of phases and delay times of the one-dimensional Anderson model with one open channel
No full textWe study the distribution of phases and of Wigner delay times for a one-dimensional Anderson model with one open channel. Our approach, based on classical Hamiltonian maps, allows us an analytical treatment. We find that the distribution of phases depends drastically on the parameter sigma(A) = sigma/sin k where sigma(2) is the variance of the disorder distribution and k the wave vector. It undergoes a transition from uniformity to singular behavior as sigma(A) increases. The distribution of delay times shows universal power-law tails l/tau(2), while the short time behavior is sigma(A) dependent
Unstable synchronization and switching among unstable attractors in spiking neural networks
No full textSignatures of classical diffusion in quantum fluctuations of two-dimensional chaotic systems
No full textWe consider a two-dimensional (2D) generalization of the standard kicked rotor and show that it is an excellent model for the study of universal features of 2D quantum systems with underlying diffusive classical dynamics. First we analyze the distribution of wave-function intensities and compare them with the predictions derived in the framework of diffusive disordered samples. Next, we turn the closed system into an open one by constructing a scattering matrix. The distribution of the resonance widths P(Gamma) and Wigner delay times (tau(W)) are investigated. The forms of these distributions are obtained for different symmetry classes and the traces of classical diffusive dynamics are identified. Our theoretical arguments are supported by extensive numerical calculations
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