10 research outputs found
Evidence of stochastic resonance in the mating behavior of Nezara viridula (L.)
We investigate the role of the noise in the mating behavior between
individuals of Nezara viridula (L.), by analyzing the temporal and spectral
features of the non-pulsed type female calling song emitted by single
individuals. We have measured the threshold level for the signal detection, by
performing experiments with the calling signal at different intensities and
analyzing the insect response by directionality tests performed on a group of
male individuals. By using a sub-threshold signal and an acoustic Gaussian
noise source, we have investigated the insect response for different levels of
noise, finding behavioral activation for suitable noise intensities. In
particular, the percentage of insects which react to the sub-threshold signal,
shows a non-monotonic behavior, characterized by the presence of a maximum, for
increasing levels of the noise intensity. This constructive interplay between
external noise and calling signal is the signature of the non-dynamical
stochastic resonance phenomenon. Finally, we describe the behavioral activation
statistics by a soft threshold model which shows stochastic resonance. We find
that the maximum of the ensemble average of the input-output cross-correlation
occurs at a value of the noise intensity very close to that for which the
behavioral response has a maximum.Comment: 6 pages, 4 figures, to appear in EPJ B (2008
Oct-1promoter region contains octamer sites and TAAT motifs recognized by Oct proteins
Consequential noise-induced synchronization of indirectly coupled self-sustained oscillators
We consider the dynamics of identical self-sustained oscillators coupled via a common linear system (beam), which is perturbed by noise. We demonstrate that increasing the noise intensity induces complete synchronization between the oscillators and, surprisingly, their in-phase synchronization with the beam. This new phenomenon of in-phase synchronization of both the oscillators and the oscillating beam arises when the noise intensity exceeds a threshold value, and can not appear in the deterministic case where the beam stably oscillates in anti-phase with the synchronized oscillators (as it is in the case of the Huygens clocks synchronization). Similar behavior persists for slightly non-identical oscillators
Consequential noise-induced synchronization of indirectly coupled self-sustained oscillators
Controlling the first-spike latency response of a single neuron via unreliable synaptic transmission
Numerical bifurcation analysis of two coupled FitzHugh-Nagumo oscillators
The behavior of neurons can be modeled by the FitzHugh-Nagumo oscillator
model, consisting of two nonlinear differential equations, which simulates the
behavior of nerve impulse conduction through the neuronal membrane. In this
work, we numerically study the dynamical behavior of two coupled
FitzHugh-Nagumo oscillators. We consider unidirectional and bidirectional
couplings, for which Lyapunov and isoperiodic diagrams were constructed
calculating the Lyapunov exponents and the number of the local maxima of a
variable in one period interval of the time-series, respectively. By numerical
continuation method the bifurcation curves are also obtained for both
couplings. The dynamics of the networks here investigated are presented in
terms of the variation between the coupling strength of the oscillators and
other parameters of the system. For the network of two oscillators
unidirectionally coupled, the results show the existence of Arnold tongues,
self-organized sequentially in a branch of a Stern-Brocot tree and by the
bifurcation curves it became evident the connection between these Arnold
tongues with other periodic structures in Lyapunov diagrams. That system also
present multistability shown in the planes of the basin of attractions.Comment: 9 pages and 8 figure