We extend the study of a computational model recently proposed for the mammalian circadian clock (Proc. Natl Acad. Sci. USA 100 (2003) 7051). The model, based on the intertwined positive and negative regulatory loops involving the Per, Cry, Bmal1, and Clock genes, can give rise to sustained circadian oscillations in conditions of continuous darkness. These limit cycle oscillations correspond to...

Magnetospheric sawtooth oscillations are observed during strong and steady solar wind driving conditions. The simulation results of our global magnetohydrodynamics (MHD) model with embedded kinetic physics show that when the total magnetic flux carried by constant exceeds a threshold, sawtooth-like magnetospheric generated. Different from previous works, this result is obtained without involvin...

This study investigates the mode transition phenomenon in a standing-wave thermoacoustic engine (TAE) by means of computational fluid dynamics (CFD). Firstly, steady-state responses TAE at selected temperature ratios are examined via continuous wavelet transform. The bifurcation diagram and spectral map indicate that, as ratio increases, experiences series bifurcations, through which first-mode...

The pathophysiology of the ventricular fibrillation that complicates digitalis intoxication was investigated. In this and other calcium-overload states, oscillations of the intracellular free calcium concentration ([Ca2+]i) have been implicated as the cause of ventricular tachyarrhythmias. We addressed two questions: 1) Are [Ca2+]i oscillations obligatory in the pathogenesis of ventricular fibr...

1. The dynamic contribution of otolith signals to three-dimensional angular vestibuloocular reflex (VOR) was studied during off-vertical axis rotations in rhesus monkeys. In an attempt to separate response components to head velocity from those to head position relative to gravity during low-frequency sinusoidal oscillations, large oscillation amplitudes were chosen such that peak-to-peak head ...

We study dynamical regimes of globally coupled genetic relaxation oscillators in the presence of small detuning. Using bifurcation analysis, we find that under strong coupling via the slow variable, the detuning can eliminate standard oscillatory solutions in a large region of the parameter space, providing the dominance of oscillation death. This result is substantially different from previous...

A very simple, one-dimensional, discrete, autonomous model of cell crawling is proposed; the model involves only three or four coupled first-order differential equations. This form is sufficient to describe many general features of cell migration, including both steady forward motion and oscillatory progress. Closed-form expressions for crawling speeds and internal forces are obtained in terms ...

In this paper, we first study the distribution of the zeros of a third degree exponential polynomial. Then we apply the obtained results to a delay model for the control of testosterone secretion. It is shown that under certain assumptions on the coefficients the steady state of the delay model is asymptotically stable for all delay values. Under another set of conditions, there is a critical d...

A numerical study has been conducted in order to understand the effects of flame curvature on soot formation laminar non-premixed flames. For fundamental understanding, canonical configuration a counterflow diffusion is employed as it exhibits essential combustion physics associated with Numerical results for steady ethylene flames confirmed that response curved governed by intricate coupling b...

General Concepts and Clinical Approach This chapter concerns abnormal eye movements that disrupt steady fixation and thereby degrade vision. We now know a good deal about the normal anatomy, physiology, and pharmacology of ocular motor control (1). Our approach is to apply this knowledge to nystagmus and other ocular oscillations, since pathophysiology provides a sounder conceptual framework th...