666 research outputs found
Anticipated synchronization and the predict-prevent control method in the FitzHugh-Nagumo model system
We study the synchronization region of two unidirectionally coupled, in a
master-slave configuration, FitzHugh-Nagumo systems under the influence of
external forcing terms. We observe that anticipated synchronization is robust
to the different types of forcings. We then use the predict-prevent control
method to suppress unwanted pulses in the master system by using the
information of the slave output. We find that this method is more efficient
than the direct control method based on the master. Finally, we observe that a
perfect matching between the parameters of the master and the slave is not
necessary for the control to be efficient. Moreover, this parameter mismatch
can, in some cases, improve the control
Stochastic thermodynamics for kinetic equations
Stochastic thermodynamics is formulated for variables that are odd under time
reversal. The invariance under spatial rotation of the collision rates due to
the isotropy of the heat bath is shown to be a crucial ingredient. An
alternative detailed fluctuation theorem is derived, expressed solely in terms
of forward statistics. It is illustrated for a linear kinetic equation with
kangaroo rates
Experimental Observation of Coherence and Stochastic Resonances in an Electronic Chua Circuit
Stochastic and coherence resonances appear in nonlinear systems subjected to
an external source of noise and are characterized by a maximum response at the
optimal value of the noise intensity. This paper shows experimentally that it
is possible to observe them in a chaotic system. To this end we have analysed
an electronic Chua circuit running in the chaotic regime and added noise to its
dynamics. In the case of coherence resonance, we observe an optimal periodicity
for the jumps between chaotic attractors, whereas in the case of stochastic
resonance we observe a maximum in the signal-to-noise ratio at the frequency of
an external sinusoidal perturbation.Comment: 6 page
Synchronization and entrainment of coupled circadian oscillators
Circadian rhythms in mammals are controlled by the neurons located in the
suprachiasmatic nucleus of the hypothalamus. In physiological conditions, the
system of neurons is very efficiently entrained by the 24-hour light-dark
cycle. Most of the studies carried out so far emphasize the crucial role of the
periodicity imposed by the light dark cycle in neuronal synchronization.
Nevertheless, heterogeneity as a natural and permanent ingredient of these
cellular interactions is seemingly to play a major role in these biochemical
processes. In this paper we use a model that considers the neurons of the
suprachiasmatic nucleus as chemically-coupled modified Goodwin oscillators, and
introduce non-negligible heterogeneity in the periods of all neurons in the
form of quenched noise. The system response to the light-dark cycle periodicity
is studied as a function of the interneuronal coupling strength, external
forcing amplitude and neuronal heterogeneity. Our results indicate that the
right amount of heterogeneity helps the extended system to respond globally in
a more coherent way to the external forcing. Our proposed mechanism for
neuronal synchronization under external periodic forcing is based on
heterogeneity-induced oscillators death, damped oscillators being more
entrainable by the external forcing than the self-oscillating neurons with
different periods.Comment: 17 pages, 7 figure
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 implementation in
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.Comment: 12 pages (RevTex format
Synchronization of Chaotic Systems by Common Random Forcing
We show two examples of noise--induced synchronization. We study a 1-d map
and the Lorenz systems, both in the chaotic region. For each system we give
numerical evidence that the addition of a (common) random noise, of large
enough intensity, to different trajectories which start from different initial
conditions, leads eventually to the perfect synchronization of the
trajectories. The largest Lyapunov exponent becomes negative due to the
presence of the noise terms.Comment: 5 pages, uses aipproc.cls and aipproc.sty (included). Five double
figures are provided as ten separate gif files. Version with (large)
postscript figures included available from
http://www.imedea.uib.es/PhysDept/publicationsDB/date.htm
Stochastic thermodynamics for Ising chain and symmetric exclusion process
We verify the finite time fluctuation theorem for a linear Ising chain at its
ends in contact with heat reservoirs. Analytic results are derived for a chain
consisting of only two spins. The system can be mapped onto a model for
particle transport, namely the symmetric exclusion process, in contact with
thermal and particle reservoirs. We modify the symmetric exclusion process to
represent a thermal engine and reproduce universal features of the efficiency
at maximum power
Diversity-induced resonance in a model for opinion formation
We study an opinion formation model that takes into account that individuals have diverse preferences when adopting an opinion regarding a particular issue. We show that the system exhibits "diversity-induced resonance” [C.J. Tessone et al. Phys. Rev. Lett. 97, 194101 (2006)], by which an external influence (for example advertising, or fashion trends) is better followed by populations having the right degree of diversity in their preferences, rather than others where the individuals are identical or have too different preferences. We support our findings by numerical simulations of the model in different network topologies and a mean-field type analytical theor
- …