Chimera States in a Two-Population Network of Coupled Pendulum-Like Elements

More than a decade ago, a surprising coexistence of synchronous and asynchronous behavior called the chimera state was discovered in networks of nonlocally coupled identical phase oscillators. In later years, chimeras were found to occur in a variety of theoretical and experimental studies of chemical and optical systems, as well as models of neuron dynamics. In this work, we study two coupled populations of pendulum-like elements represented by phase oscillators with a second derivative term multiplied by a mass parameter $m$ and treat the first order derivative terms as dissipation with parameter $\epsilon>0$. We first present numerical evidence showing that chimeras do exist in this system for small mass values $0<m<<1$. We then proceed to explain these states by reducing the coherent population to a single damped pendulum equation driven parametrically by oscillating averaged quantities related to the incoherent population

Integromics network meta-analysis on cardiac aging offers robust multi-layer modular signatures and reveals micronome synergism

10.1186/s12864-015-1256-3BMC Genomics16114

Progressive gender differences of structural brain networks in healthy adults: A longitudinal, diffusion tensor imaging study

10.1371/journal.pone.0118857PLoS ONE103e011885

OLYMPUS: An automated hybrid clustering method in time series gene expression. Case study: Host response after Influenza A (H1N1) infection

10.1016/j.cmpb.2013.05.025Computer Methods and Programs in Biomedicine1113650-661CMPB

Identification of coupling direction: Application to cardiorespiratory interaction

INTRODUCTION Theoretical insigths in nonlinear dynamics have been widely used in time series analysis [1]. In particular, the concepts of generalized [2] and phase [3-5] synchronization have been exploited for the identi cation of interdependencies between coupled sub(systems) from multivariate data and have found a number of applications in the studies of biological time series [5, 6, 8-11]. One can formulate two main problems in such an analysis. The rst problem is to reveal whether the systems under investigation are coupled and to quantify the intensity of interaction, while the second one is to characterize the driver - response (causal) relationships, or directionality of coupling. Many natural phenomena can be modeled by coupled irregular self-sustained oscillators. The description of a weak interaction between such systems can be reduced to the phase dynamics [5, 12]. Hence, if one considers an inverse problem - characterization of weak coupling from data - it is sucient t

Time-Frequency Analysis of Somatosensory Evoked High-Frequency (600 Hz) Oscillations as an Early Indicator of Arousal Recovery after Hypoxic-Ischemic Brain Injury

Cardiac arrest (CA) remains the leading cause of coma, and early arousal recovery indicators are needed to allocate critical care resources properly. High-frequency oscillations (HFOs) of somatosensory evoked potentials (SSEPs) have been shown to indicate responsive wakefulness days following CA. Nonetheless, their potential in the acute recovery phase, where the injury is reversible, has not been tested. We hypothesize that time-frequency (TF) analysis of HFOs can determine arousal recovery in the acute recovery phase. To test our hypothesis, eleven adult male Wistar rats were subjected to asphyxial CA (five with 3-min mild and six with 7-min moderate to severe CA) and SSEPs were recorded for 60 min post-resuscitation. Arousal level was quantified by the neurological deficit scale (NDS) at 4 h. Our results demonstrated that continuous wavelet transform (CWT) of SSEPs localizes HFOs in the TF domain under baseline conditions. The energy dispersed immediately after injury and gradually recovered. We proposed a novel TF-domain measure of HFO: the total power in the normal time-frequency space (NTFS) of HFO. We found that the NTFS power significantly separated the favorable and unfavorable outcome groups. We conclude that the NTFS power of HFOs provides earlier and objective determination of arousal recovery after CA