We investigate the dynamical behavior of simple modules composed of two genes with two or three regulating connections. Continuous dynamics for mRNA and protein concentrations is compared to a Boolean model for gene activity. Using a generalized method, we study within a single framework different continuous models and different types of regulatory functions, and establish conditions under whic...

The effects of driver experience delay on the dynamics of a nonlinear day-to-day traffic model are investigated. When parameters are varied oscillations may arise via flip and Neimark-Sacker bifurcations in the non-delayed and delayed cases, respectively. The nonlinear behavior is analyzed using normal form calculations which are validated by numerical continuation and simulation. It is shown t...

We investigate Bloch oscillations of interacting cold atoms in a mean-field framework. In general, atom-atom interaction causes dephasing and destroys Bloch oscillations. Here we show that Bloch oscillations are persistent if the interaction is modulated harmonically with suitable frequency and phase. For other modulations, Bloch oscillations are rapidly damped. We explain this behavior in term...

The observed quasi-periodic oscillations (QPOs) in low-mass X-ray binaries have been suggested to be probably related to the characteristic oscillation modes in the inner part of a relativistic accretion disk. In this paper we study the trapped feature of these oscillation modes by considering the radial perturbations and viscosity effects. We find that the trapped oscillations are amplified si...

*Correspondence: Raymond J. Spiteri, Numerical Simulation Laboratory, Department of Computer Science, University of Saskatchewan, 176 Thorvaldson Building, 110 Science Place, Saskatoon, SK S7N 5C9, Canada e-mail: [email protected] The bidomain model is a popular model for simulating electrical activity in cardiac tissue. It is a continuum-based model consisting of non-linear ordinary differen...

Self-sustained current oscillations in weakly coupled superlattices are studied by means of a self-consistent microscopic model of sequential tunneling, naturally including boundary conditions. Well-to-well hopping and recycling of charge monopole domain walls produce current spikes—high-frequency modulation— superimposed on the oscillation. For highly doped injecting contacts, the self-oscilla...

We present an overview of mechanisms responsible for simple or complex oscillatory behavior in metabolic and genetic control networks. Besides simple periodic behavior corresponding to the evolution toward a limit cycle we consider complex modes of oscillatory behavior such as complex periodic oscillations of the bursting type and chaos. Multiple attractors are also discussed, e.g., the coexist...

Westerlund, J. 2000. Pulsatile insulin release from single islets of Langerhans. Acta Universitatis Upsaliensis. Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine 945. 49 pp. Uppsala. ISBN 91-554-4782-1 Insulin release from single islets of Langerhans is pulsatile. The secretory activities of the islets in the pancreas are coordinated resulting in plasma insulin osci...

In the rat olfactory bulb (OB), fast oscillations of the local field potential (LFP) are observed during the respiratory cycle. Gamma-range oscillations (40-90 Hz) occur at the end of inspiration, followed by beta-range oscillations (15-30 Hz) during exhalation. These oscillations are highly stereotypical, and their frequencies are stable under various conditions. In this study, we investigate ...