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Weiwei Su

Publications and source records attributed to Weiwei Su.

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Distinguishing pairwise and higher-order interactions in coupled oscillators from time series

Rhythmic phenomena, which are ubiquitous in biological systems, are typically modelled as systems of coupled limit cycle oscillators. Recently, there has been an increased interest in understanding the impact of higher-order interactions on the population dynamics of coupled oscillators. Meanwhile, the estimation of a mathematical model from experimental data is an essential step in understanding the dynamics of real-world complex systems. In coupled oscillator systems, identifying the type of interaction (e.g. pairwise or three-body) is challenging, because different interactions can exhibit similar dynamical states in experimental conditions. In this study, we have developed a method based on the adaptive LASSO (Least Absolute Shrinkage and Selection Operator) to infer the interactions among oscillators from time series data. The proposed method successfully identifies the type of interaction and estimates the probabilities of pairwise and three-body couplings. Through systematic analysis of synthetic datasets, we have demonstrated that our method outperforms two baseline methods, LASSO and OLS (Ordinary Least Squares), in accurately inferring the topology and strength of couplings between oscillators. Furthermore, the proposed method is applied to human brain network data, demonstrating its practical utility. Finally, we extend the method to more general oscillatory systems, including those exhibiting the deformation of limit cycles and those with four-body interactions. These results suggest that our method is a promising tool for identifying interaction mechanisms in oscillatory systems.

nlin.CD

Transportation efficiency of hydrodynamically coupled spherical oscillators in low Reynolds number fluids

Most bacteria are driven by the cilia or flagella, consisting of a long filament and a rotary molecular motor through a short flexible hook. The beating pattern of these filaments shows synchronization properties from hydrodynamic interactions, especially in low Reynolds number fluids. Here, we introduce a model based on simple spherical oscillators which execute oscillatory movements in one dimension by an active force, as a simplified imitation of the movements of cilia or flagella. It is demonstrated that the flow, measured by the net transportation of a test particle, is generated by a chain of oscillators and enhanced by the hydrodynamic interactions between beads, with supports from both perturbative and numerical results. Transportation efficiency also highly correlates with hydrodynamic interactions. Increments of bead numbers are generally expected to produce stronger flow and efficiency, at least for small numbers of beads.

physics.flu-dyn