Computational Analysis and Bifurcation of Regular and Chaotic Ca2+ Oscillations

This study investigated the stability and bifurcation of a nonlinear system model developed by Marhl et al. based on the total Ca2+ concentration among three different Ca2+ stores. In this study, qualitative theories of center manifold and bifurcation were used to analyze the stability of equilibria. The bifurcation parameter drove the system to undergo two supercritical bifurcations. It was hypothesized that the appearance and disappearance of Ca2+ oscillations are driven by them. At the same time, saddle-node bifurcation and torus bifurcation were also found in the process of exploring bifurcation. Finally, numerical simulation was carried out to determine the validity of the proposed approach by drawing bifurcation diagrams, time series, phase portraits, etc.

Механизмы перехода от ритмической активности к пачечной в модели ноцицептивного нейрона

The transitions from tonic spiking to bursting for the nociceptive neuron model have been studied with changing the external stimulus value. The presence of the fold limit cycle bifurcation in the structure of the bifurcation diagram of the fast subsystem and the torus bifurcation in the structure of the bifurcation diagram of the full system lead to the emergence of special solutions of the type torus canards in these transitions. This confirms the assumption that torus canards are an obligatory feature for transitions between rhythmic and burst discharges

A POSSIBLE NEW ROUTE TO CHAOS VIA SEMICONDUCTOR SUPERLATTICES

Our current understanding of routes to chaos is mainly based on torus bifurcation where new periods are generated, the period-doubling mechanism revealed in the logistic map, and intermittency where periodic and burst motion appear alternatively. We present a possible new route to chaos based on our geometric picture of the frequency-locking of limit-cycles in semiconductor superlattices. In the period-double route and/or its variations, the period increases exponentially with bifurcation order, whereas the period in the new route increases linearly with the order of bifurcations.