Biomedical subjects

S E Mangioni

Publications and source records attributed to S E Mangioni.

3 recordsLinked to original sources

PubMed2003

Limit cycle induced by multiplicative noise in a system of coupled Brownian motors.

We study a model consisting of N nonlinear oscillators with global periodic coupling, and local multiplicative and additive noises. The model was shown to undergo a nonequilibrium phase transition towards a broken-symmetry phase exhibiting noise-induced "ratchet" behavior. A previous study [H. S. Wio, S. Mangioni, and R. Deza, Physica D 168-169, 184 (2002)] focused on the relationship between the character of the hysteresis loop, the number of "homogeneous" mean-field solutions, and the shape of the stationary mean-field probability distribution function. Here, we show-as suggested by the absence of stable solutions when the load force is beyond a critical value-the existence of a limit cycle induced by both multiplicative noise and global periodic coupling.

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PubMed2002

Coupling-reentrant phase transition, complex hysteretic behavior, and efficiency optimization in coupled phase oscillators submitted to colored flashing potentials.

A recent mean-field analysis of a model consisting of N nonlinear phase oscillators-under the joint influence of global periodic coupling with strength K0 and of local multiplicative and additive noises-has shown a nonequilibrium phase transition towards a broken-symmetry phase exhibiting noise-induced transport, or "ratchet" behavior. In a previous paper we focused on the relationship between the character of the (mean velocity vs load force F) hysteresis loop, the number of "homogeneous" mean-field solutions, and the shape of the stationary mean-field probability distribution function (PDF). Here we assume that the multiplicative noises of the model are Ornstein-Uhlenbeck with common strength Q and self-correlation time tau. By resorting to an effective Markovian approximation, we study the tau dependence of the phase boundary, and that of the line signaling the transition from the "interaction-driven regime" to the "noise-driven regime." We also study-for selected representative points of the K0 vs Q phase diagram-the tau dependence of the transport properties induced by coupling and colored multiplicative noise (including the efficiency epsilon of the mechanical rectification process) and that of the above-mentioned PDF.

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PubMed2001

Transition from anomalous to normal hysteresis in a system of coupled Brownian motors: a mean-field approach.

We address a recently introduced model describing a system of periodically coupled nonlinear phase oscillators submitted to multiplicative white noises, wherein a ratchetlike transport mechanism arises through a symmetry-breaking noise-induced nonequilibrium phase transition. Numerical simulations of this system reveal amazing novel features such as negative zero-bias conductance and anomalous hysteresis, explained by performing a strong-coupling analysis in the thermodynamic limit. Using an explicit mean-field approximation, we explore the whole ordered phase finding a transition from anomalous to normal hysteresis inside this phase, estimating its locus, and identifying (within this scheme) a mechanism whereby it takes place.

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