Biomedical subjects

D-U Hwang

Publications and source records attributed to D-U Hwang.

6 recordsLinked to original sources

PubMed2006

Synchronization in dynamical networks: evolution along commutative graphs.

Starting from an initial wiring of connections, we show that the synchronizability of a network can be significantly improved by evolving the graph along a time dependent connectivity matrix. We consider the case of connectivity matrices that commute at all times, and compare several approaches to engineer the corresponding commutative graphs. In particular, we show that synchronization in a dynamical network can be achieved even in the case in which each individual commutative graphs does not give rise to synchronized behavior.

Journal Article↗

PubMed2006

Awaking and sleeping of a complex network.

A network with a logistic-like local dynamics is considered. We implement a mean-field multiplicative coupling among first-neighbor nodes. When the coupling parameter is small, the dynamics is dissipated and there is no activity: the network is turned off. For a critical value of the coupling, a non-null stable synchronized state, which represents a turned on network, emerges. This global bifurcation is independent of the network topology. We characterize the bistability of the system by studying how to perform the transition, which is now topology dependent, from the active state to that with no activity, for the particular case of a scale-free network. This could be a naive model for the wakening and sleeping of a brain-like system, i.e., a multi-component system with two different dynamical behaviors.

Animals↗

PubMed2006

Synchronizing weighted complex networks.

Real networks often consist of local units, which interact with each other via asymmetric and heterogeneous connections. In this work, we explore the constructive role played by such a directed and weighted wiring for the synchronization of networks of coupled dynamical systems. The stability condition for the synchronous state is obtained from the spectrum of the respective coupling matrices. In particular, we consider a coupling scheme in which the relative importance of a link depends on the number of shortest paths through it. We illustrate our findings for networks with different topologies: scale free, small world, and random wirings.

Action Potentials↗

PubMed2005

Coherence resonance in excitable electronic circuits in the presence of colored noise.

We give evidence of coherence resonance in an excitable electronic circuit whose dynamics obeys the FitzHugh-Nagumo model system, under the application of different noise sources, ranging from Gaussian white noise to colored 1/f2 noises. The resonance behavior can be significantly reinforced when experimental parameters are tuned in order to place the stable fixed point closer to the excitability threshold of spiking behavior, as well as when the time scales of the circuit are properly modified. A quantitative description of the effects of noise correlations in inducing the resonant behavior is provided.

Journal Article↗

PubMed2005

Synchronization is enhanced in weighted complex networks.

The propensity for synchronization of complex networks with directed and weighted links is considered. We show that a weighting procedure based upon the global structure of network pathways enhances complete synchronization of identical dynamical units in scale-free networks. Furthermore, we numerically show that very similar conditions hold also for phase synchronization of nonidentical chaotic oscillators.

Biophysics↗

PubMed2005

Synchronization in complex networks with age ordering.

The propensity for synchronization is studied in a complex network of asymmetrically coupled units, where the asymmetry in a given link is determined by the relative age of the involved nodes. In growing scale-free networks, synchronization is enhanced when couplings from older to younger nodes are dominant. We describe the requirements for such an effect in a more general context and compare with the situations in nongrowing random networks with and without a degree ordering.

Computer Systems↗