We study the quasi-periodicity phenomena occurring at the transition between tonic spiking and bursting activities in exemplary biologically plausible Hodgkin-Huxley type models of individual cells and reduced phenomenological models with slow and fast dynamics. Using the geometric slow-fast dissection and the parameter continuation approach, we show that the transition is due to either the torus bifurcation or the period-doubling bifurcation of a stable periodic orbit on the 2D slow-motion manifold near a characteristic fold. Various torus bifurcations including stable and saddle torus-canards, resonant tori, the co-existence of nested tori, and the torus breakdown leading to the onset of complex and bistable dynamics in such systems are examined too.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1063/1.5042078 | DOI Listing |
Ann Henri Poincare
February 2024
Dipartimento di Matematica "Federigo Enriques", Università degli Studi di Milano, Via Cesare Saldini 50, 20133 Milan, Italy.
In this paper, we investigate the inviscid limit for time-quasi-periodic solutions of the incompressible Navier-Stokes equations on the two-dimensional torus , with a small time-quasi-periodic external force. More precisely, we construct solutions of the forced Navier-Stokes equation, bifurcating from a given time quasi-periodic solution of the incompressible Euler equations and admitting vanishing viscosity limit to the latter, uniformly for all times and independently of the size of the external perturbation. Our proof is based on the construction of an approximate solution, up to an error of order and on a fixed point argument starting with this new approximate solution.
View Article and Find Full Text PDFPhys Rev E
September 2024
Department of Physics, Indian Institute of Technology Delhi, Delhi 110016, India.
We use Clifford's geometric algebra to extend the Stuart-Landau system to dimensions D>2 and give an exact solution of the oscillator equations in the general case. At the supercritical Hopf bifurcation marked by a transition from stable fixed-point dynamics to oscillatory motion, the Jacobian matrix evaluated at the fixed point has N=⌊D/2⌋ pairs of complex conjugate eigenvalues which cross the imaginary axis simultaneously. For odd D there is an additional purely real eigenvalue that does the same.
View Article and Find Full Text PDFChaos
August 2024
Laboratory of Dynamical Systems and Applications, National Research University Higher School of Economics, 25/12 Bolshaya Pecherskaya Ulitsa, 603155 Nizhny Novgorod, Russia.
We propose a simple model-two-parameter family of diffeomorphisms of a two-dimensional torus. Combining analytical and numerical methods, we find regions in the parameter plane such that each diffeomorphism of the family is hyperbolic and describe the structure of the corresponding hyperbolic sets. We also study bifurcations on the boundaries of these regions, which lead to the change of hyperbolicity type (from Anosov diffeomorphisms to DA-diffeomorphisms).
View Article and Find Full Text PDFPhys Rev E
April 2024
Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong.
We numerically explore the two-dimensional, incompressible, isothermal flow through a wavy channel, with a focus on how the channel geometry affects the routes to chaos at Reynolds numbers between 150 and 1000. We find that (i) the period-doubling route arises in a symmetric channel, (ii) the Ruelle-Takens-Newhouse route arises in an asymmetric channel, and (iii) the type-II intermittency route arises in both asymmetric and semiwavy channels. We also find that the flow through the semiwavy channel evolves from a quasiperiodic torus to an unstable invariant set (chaotic saddle), before eventually settling on a period-1 limit-cycle attractor.
View Article and Find Full Text PDFChaos
January 2024
Department of Physics, Faculty of Science, University of Yaoundé I, PO Box 812 Yaoundé, Cameroon.
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!