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C Masoller

Publications and source records attributed to C Masoller.

13 recordsLinked to original sources
PubMed2005

Steady-state stabilization due to random delays in maps with self-feedback loops and in globally delayed-coupled maps.

We study the stability of the fixed-point solution of an array of mutually coupled logistic maps, focusing on the influence of the delay times, , of the interaction between the and maps. Two of us recently reported [Phys. Rev. Lett. 94, 134102 (2005)] that if are random enough, the array synchronizes in a spatially homogeneous steady state. Here we study this behavior by comparing the dynamics of a map of an array of delayed-coupled maps with the dynamics of a map with self-feedback delayed loops. If is sufficiently large, the dynamics of a map of the array is similar to the dynamics of a map with self-feedback loops with the same delay times. Several delayed loops stabilize the fixed point, when the delays are not the same; however, the distribution of delays plays a key role; if the delays are all odd a periodic orbit (and not the fixed point) is stabilized. We present a linear stability analysis and apply some mathematical theorems that explain the numerical results.

Journal Article↗
PubMed2005

Random delays and the synchronization of chaotic maps.

We investigate the dynamics of an array of chaotic logistic maps coupled with random delay times. We report that for adequate coupling strength the array is able to synchronize, in spite of the random delays. Specifically, we find that the synchronized state is a homogeneous steady state, where the chaotic dynamics of the individual maps is suppressed. This synchronization behavior is largely independent of the connection topology and depends mainly on the average number of links per node. We carry out a statistical linear stability analysis that confirms the numerical results and provides a better understanding of the nontrivial roles of random delayed interactions.

Logistic Models↗
PubMed2004

Influence of time-delayed feedback in the firing pattern of thermally sensitive neurons.

We explore the dynamics of a Hodgkin-Huxley-type model for thermally sensitive neurons that exhibit intrinsic oscillatory activity. The model is modified to include a feedback loop that is represented by two parameters: the synaptic strength and the transmission delay time. We analyze the dynamics of the neuron depending on the temperature, the synaptic strength, and the delay time. We find parameter regions where the effect of the recurrent connexion is excitatory, inducing spikes or trains of spikes, and regions where it is inhibitory, reducing or eliminating completely the spiking behavior. We characterize the complex interplay of the intrinsic dynamics of the neuron with the recurrent feedback input and a noisy input.

Action Potentials↗
PubMed2004

Distribution of residence times in bistable noisy systems with time-delayed feedback.

We analyze theoretically and experimentally the residence time distribution of bistable systems in the presence of noise and time-delayed feedback. We explain various nonexponential features of the residence time distribution using a two-state model and obtain a quantitative agreement with an experiment based on a Schmitt trigger. The limitations of the two-state model are also analyzed theoretically and experimentally using a semiconductor laser with optoelectronic feedback.

Journal Article↗
PubMed2004

Experimental investigation of a bistable system in the presence of noise and delay.

We experimentally analyze the behavior of a non-Markovian bistable system with noise, using a vertical cavity surface emitting laser with time-delayed optoelectronic feedback. The effects of the delayed feedback are observed in the probability distribution of the residence times of the two orthogonal polarization states, and in the polarization-resolved power spectrum. They agree well with recent theoretical predictions based on a two-state model with transition rates depending on an earlier state of the system. We also observe experimentally and explain theoretically that the residence time probability distribution deviates from exponential decay for residence times close to (and smaller than) the delay time.

Journal Article↗
PubMed2003

Delay-induced synchronization phenomena in an array of globally coupled logistic maps.

We study the synchronization of a linear array of globally coupled identical logistic maps. We consider a time-delayed coupling that takes into account the finite velocity of propagation of the interactions. We find globally synchronized states in which the elements of the array evolve along a periodic orbit of the uncoupled map, while the spatial correlation along the array is such that an individual map sees all other maps in his present, current, state. For values of the nonlinear parameter such that the uncoupled maps are chaotic, time-delayed mutual coupling suppresses the chaotic behavior by stabilizing a periodic orbit that is unstable for the uncoupled maps. The stability analysis of the synchronized state allows us to calculate the range of the coupling strength in which global synchronization can be obtained.

Journal Article↗
PubMed2003

Anticipating the response of excitable systems driven by random forcing.

We study the regime of anticipated synchronization in unidirectionally coupled model neurons subject to a common external aperiodic forcing that makes their behavior unpredictable. We show numerically and by analog hardware electronic circuits that, under appropriate coupling conditions, the pulses fired by the slave neuron anticipate (i.e., predict) the pulses fired by the master neuron. This anticipated synchronization occurs even when the common external forcing is white noise.

Action Potentials↗
PubMed2003

Distribution of residence times of time-delayed bistable systems driven by noise.

I study bistable time-delayed feedback systems driven by noise. Based on a two-state model with transition rates depending on the earlier state of the system I calculate analytically the residence-time distribution function. I show that the distribution function has a detailed structure, reflective of the effect of the feedback. By using an adequate indicator I give evidence of resonant behavior in dependence on the noise level. I also predict that this feedback-induced effect might be observed in two well-known optical bistable systems.

Axons↗
PubMed2002

Synchronization regimes of optical-feedback-induced chaos in unidirectionally coupled semiconductor lasers.

We numerically study the synchronization of two unidirectionally coupled single-mode semiconductor lasers in a master-slave configuration. The master laser is an external-cavity laser that operates in a chaotic regime while for the slave laser we consider two configurations. In the first one, the slave laser is also an external-cavity laser, subjected to, its own optical feedback and the optical injection from the master laser. In the second one, the slave laser is subject only to the optical injection from the master laser. Depending on the operating conditions the synchronization between the two lasers, whenever it exists, can be either isochronous or anticipated. We perform a detailed study of the parameter regions in which these synchronization regimes occur and how small variations of parameter yield one or the other type of synchronization or an unsynchronized regime.

Journal Article↗
PubMed2002

Noise-induced resonance in delayed feedback systems.

We study the influence of noise in the dynamics of a laser with optical feedback. For appropriate choices of the feedback parameters, several attractors coexist, and large enough noise induces jumps among the attractors. Based on the residence times probability density, it is shown that with increasing noise the dynamics of attractor jumping exhibits a resonant behavior, which is due to the interplay of noise and delayed feedback. It is also shown that this type of resonance is not specific to the model equations used, since it also occurs in other delay differential equations.

Journal Article↗
PubMed2001

Delayed coupling of logistic maps.

We study the synchronization of logistic maps in a one-way coupling configuration. The master system is coupled to the slave system with a delay n(1), and the slave is a delayed logistic map with a delay n(2). We show that when the slave system has no delay (n(2)=0), perfectly synchronized solutions exist for strong enough coupling. In these solutions the slave variable y is retarded with respect to the master variable x with a retardation equal to the delay of the coupling [y(i+n(1))=x(i)]. When n(2) not equal 0, a regime of generalized synchronization is observed, where y(i+n(1)) is synchronized with x(i), but not completely, since the master and the slave systems obey different maps. We introduced a similarity function as an indicator of the degree of synchronization and, using a noisy master source, distinguished synchronization from noise-induced correlations.

Journal Article↗
PubMed2001

Anticipation in the synchronization of chaotic semiconductor lasers with optical feedback.

The synchronization of chaotic semiconductor lasers with optical feedback is studied numerically in a one-way coupling configuration, in which a small amount of the intensity of one laser (master laser) is injected coherently into the other (slave laser). A regime of anticipated synchronization is found, in which the intensity of the slave laser is synchronized to the future chaotic intensity of the master laser. Anticipation is robust to small noise and parameter mismatches, but in this case the synchronization is not complete. It is also shown that anticipated synchronization occurs in coupled time-delay systems, when the coupling has a delay that is less than the delay of the systems.

Journal Article↗