536 research outputs found
Noise, Synchrony and Correlations at the Edge of Chaos
We study the effect of a weak random additive noise in a linear chain of N
locally-coupled logistic maps at the edge of chaos. Maps tend to synchronize
for a strong enough coupling, but if a weak noise is added, very intermittent
fluctuations in the returns time series are observed. This intermittency tends
to disappear when noise is increased. Considering the pdfs of the returns, we
observe the emergence of fat tails which can be satisfactorily reproduced by
-Gaussians curves typical of nonextensive statistical mechanics.
Interoccurrence times of these extreme events are also studied in detail.
Similarities with recent analysis of financial data are also discussed.Comment: 6 pages, 8 figures, new figure added - Version accepted for
publication in Physical Review
Mesenchymal stem cells as promoters, enhancers, and playmakers of the translational regenerative medicine
Since their first isolation and characterization by Friedenstein et al. in 1974, mesenchymal stem cells (MSCs) were proven essential for tissue regeneration and homeostasis. Over the years, thanks to a better understanding of the molecular mechanisms underlying the therapeutic effects of MSCs, several approaches with MSC-based therapies have been proposed, in order to treat different human diseases. In this light, MSCs are currently being tested in preclinical in vivo settings as well as in early-stage clinical trials for their ability to modulate immune responses, fostering wound healing and tissue regeneration of various tissue types and organs, including the skin, bone, cartilage, brain, muscle, and tendons
Detection of Complex Networks Modularity by Dynamical Clustering
Based on cluster de-synchronization properties of phase oscillators, we
introduce an efficient method for the detection and identification of modules
in complex networks. The performance of the algorithm is tested on computer
generated and real-world networks whose modular structure is already known or
has been studied by means of other methods. The algorithm attains a high level
of precision, especially when the modular units are very mixed and hardly
detectable by the other methods, with a computational effort on
a generic graph with nodes and links.Comment: 5 pages, 2 figures. Version accepted for publication on PRE Rapid
Communications: figures changed and text adde
Analysis of Self-Organized Criticality in the Olami-Feder-Christensen model and in real earthquakes
We perform a new analysis on the dissipative Olami-Feder-Christensen model on
a small world topology considering avalanche size differences. We show that
when criticality appears the Probability Density Functions (PDFs) for the
avalanche size differences at different times have fat tails with a q-Gaussian
shape. This behaviour does not depend on the time interval adopted and is found
also when considering energy differences between real earthquakes. Such a
result can be analytically understood if the sizes (released energies) of the
avalanches (earthquakes) have no correlations. Our findings support the
hypothesis that a self-organized criticality mechanism with long-range
interactions is at the origin of seismic events and indicate that it is not
possible to predict the magnitude of the next earthquake knowing those of the
previous ones.Comment: 5 pages, 3 figures. New version accepted for publication on PRE Rapid
Communication
Incomplete equilibrium in long-range interacting systems
We use a Hamiltonian dynamics to discuss the statistical mechanics of
long-lasting quasi-stationary states particularly relevant for long-range
interacting systems. Despite the presence of an anomalous single-particle
velocity distribution, we find that the Central Limit Theorem implies the
Boltzmann expression in Gibbs' -space. We identify the nonequilibrium
sub-manifold of -space characterizing the anomalous behavior and show
that by restricting the Boltzmann-Gibbs approach to this sub-manifold we obtain
the statistical mechanics of the quasi-stationary states.Comment: Title changed, throughout revision of the tex
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