Explicit internal signal stochastic resonance in a chemical model driven by colored noise

Estimation of stochastic colored noise signal driving DNAPLs degradation kinetics in the natural water environment

Little attention has been devoted to the characterization of colored noise in stochastic modeling systems. This study aims to propose an integrated numerical-simulation and statistical-inference method for the characterization of individual and mixed colored noises driving the DNAPL degradation kinetics. Through the method, the properties of colored noise (i.e. intensity and time correlation) can be identified statistically. Results for the estimations indicate that the method is useful for identifying the colored noise since the regression equations have high R square values and most of the relative errors of the estimates are below 40%. It is also found that (i) the more the repeated experiments, the higher the estimation accuracy; (ii) the larger the true value, the higher the estimation accuracy; (iii) a large number of statistical samples does not always imply high estimation accuracy. Moreover, the increase in both number of samples and interval of sampling is not helpful in enhancing the estimation accuracy. Results from the estimation of the mixed multiplicative colored-noise also show that the estimates can be regarded to be acceptable. Future studies will be needed for estimation of other types of mixed additive and multiplicative colored noises.

Explicit calcium bursting stochastic resonance

In the present work the influence of internal noise resulting from small cell volume on bursting calcium oscillations is studied. With the internal noise switched on, the center of the main peak in the PSD (power spectrum density) was modified by internal noise. With increasing of the cell volume, the calculated signal-to-noise ratio (SNR) undergoes a maximum, which is referred in the present work as explicit bursting stochastic resonance. In addition, another quantity, the correlation time is used to measure the coherence of bursting oscillations. We demonstrate that the correlation time of the oscillations also exhibits a maximum at a certain cell volume.

Signal transduction in a coupled hormone system: selective explicit internal signal stochastic resonance and its control

Cooperative interactions of signal transduction and environmental noise are investigated with a coupled hormone system, in which selective explicit internal signal stochastic resonance (EISSR) is observed. More specifically, the large peak of a period-2 oscillation (i.e., a strong signal) is greatly amplified by the environmental noise while the small peak (i.e., a weak signal) does not exhibit cooperative interactions with noise. The EISSR phenomenon could be controlled by adjusting the frequency or amplitude of an external signal and a critical amplitude for external signal is found. Significantly, the maximal signal-to-noise ratio increases almost linearly with the increment of control parameter, despite that the magnitude of the large peak is decreased. In addition, the noise does not alter the fundamental frequencies of the strong signal and the weak signal, which implicates that the system can keep its intrinsic oscillatory state and resist the effect of environmental fluctuations.

Controlling of explicit internal signal stochastic resonance by external signal

Explicit internal signal stochastic resonance (EISSR) is investigated in a model of energy transduction of molecular machinery when noise is added to the region of oscillation in the presence of external signal (ES). It is found that EISSR could be controlled, i.e., enhanced or suppressed by adjusting frequency (omega(e)) and amplitude (A) of ES, and that there exits an optimal frequency for ES, which makes EISSR strength reach the maximum. Meanwhile, a critical amplitude (A(c)) is found, which is a threshold of occurrence of EISSR. Finally, the difference and similarity between EISSR and IISSR (implicit internal signal stochastic resonance) are discussed.

Internal stochastic resonance under two-parameter modulation in intercellular calcium ion oscillations

Internal stochastic resonance (ISR) in a model of intercellular calcium ion oscillations is investigated under the modulation of two parameters, viz., degree of extracellular stimulation (beta) and leak rate (k(f)). ISR can occur when either beta or k(f) is subjected to a noise. Internal stochastic biresonance (ISBR) can occur when noise is added to the two parameters simultaneously. The distance to the bifurcation point is found to be able to enhance or suppress the ISBR, and to affect the number of peaks of ISR.

Internal stochastic resonance in two coupled liquid membrane oscillators

Internal stochastic resonance (ISR) is investigated in two coupled liquid membrane oscillators when only one oscillator is subjected to environmental noise in the absence of an external signal. Comparing the responses of both subsystems, it is found that enhancement or suppression of ISR for each oscillator depends on the coupling strength, that synchronization of the two oscillators can occur only at strong coupling strength, and that ISR without tuning can also occur under certain conditions in the above-mentioned models.