نتایج جستجو برای: stable oscillations
تعداد نتایج: 305528 فیلتر نتایج به سال:
The high burden of syphilis in China presents a unique opportunity to examine temporal trends. This study used wavelet transformation and Fourier analysis to assess the presence of temporal oscillations in the incidence of syphilis among adults, gonorrhea, and congenital syphilis over 11 years in China's largest province. This study found a significant annual oscillation trend in the incidence ...
The concept of the brain as a critical dynamical system is very attractive because systems close to criticality are thought to maximize their dynamic range of information processing and communication. To date, there have been two key experimental observations in support of this hypothesis: (i) neuronal avalanches with power law distribution of size and (ii) long-range temporal correlations (LRT...
Brain oscillations are increasingly the subject of electrophysiological studies probing their role in the functioning and dysfunction of the human brain. In recent years this research area has seen rapid and significant changes in the experimental approaches and analysis methods. This article reviews these developments and provides a structured overview of experimental approaches, spectral anal...
We rely on sustained attention to protect task performance against fatigue and distraction. Time-related variations in attention correlate with amplitude changes of specific cortical oscillations. However, the ways in which these oscillations might support sustained attention, how these oscillations are controlled, and the extent to which they influence one another remain unclear. We address th...
This paper outlines a geometric interpretation of flows generated by the collisionless Boltzmann equation, focusing in particular on the coarse-grained approach towards a time-independent equilibrium. The starting point is the recognition that the collisionless Boltzmann equation is a noncanonical Hamiltonian system with the distribution function f as the fundamental dynamical variable, the mea...
We investigate globally coupled stochastic three-state oscillators, which we consider as general models of stochastic excitable systems. We compare two situations:in the first case the transitions between the three states of each unit 1 → 2 → 3 → 1 are determined by Poissonian waiting time distributions. In the second case only transition 1 → 2 is Poissonian whereas the others are deterministic...
That oscillations of the cytoplasmic free Ca(2+) concentration ([Ca(2+)](i)) in beta-cells induce oscillations of insulin secretion is not disputed, but whether metabolism-driven oscillations of secretion can occur in the absence of [Ca(2+)](i) oscillations is still debated. Because this possibility is based partly on the results of experiments using islets from aged, hyperglycemic, hyperinsuli...
Using a nonlocal time-dependent theory of convection, we have calculated the linear non-adiabatic oscillations of the Horizontal Branch (HB) stars, with both the dynamic and thermodynamic coupling between convection and oscillations carefully treated. Turbulent pressure and turbulent viscosity have been included consistently in our equations of non-adiabatic pulsation. When the coupling between...
Insulin is secreted in discrete insulin secretory bursts. Regulation of insulin release is accomplished almost exclusively by modulation of insulin pulse mass, whereas the insulin pulse interval remains stable at approximately 4 min. It has been reported that in vivo insulin pulses can be entrained to a pulse interval of approximately 10 min by infused glucose oscillations. If oscillations in g...
We consider the equation x00(t) = x0(t) + F (x(t); t) signx(t h); = const > 0; h = const > 0; which is a model for a scalar system with a discontinuous negative delayed feedback, and study the dynamics of oscillations with emphasis on the existence, frequency and stability of periodic oscillations. Our main conclusion is that, in the autonomous case F (x; t) F (x), for jF (x)j < 1, there are pe...
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