6,846 research outputs found
Two distinct desynchronization processes caused by lesions in globally coupled neurons
To accomplish a task, the brain works like a synchronized neuronal network
where all the involved neurons work together. When a lesion spreads in the
brain, depending on its evolution, it can reach a significant portion of
relevant area. As a consequence, a phase transition might occur: the neurons
desynchronize and cannot perform a certain task anymore. Lesions are
responsible for either disrupting the neuronal connections or, in some cases,
for killing the neuron. In this work, we will use a simplified model of
neuronal network to show that these two types of lesions cause different types
of desynchronization.Comment: 5 pages, 3 figure
Towards the Holy Grail: combining system dynamics and discrete-event simulation in healthcare
The idea of combining discrete-event simulation and system dynamics has been a topic of debate in theoperations research community for over a decade. Many authors have considered the potential benefits ofsuch an approach from a methodological or practical standpoint. However, despite numerous examples ofmodels with both discrete and continuous parameters in the computer science and engineering literature,nobody in the OR field has yet succeeded in developing a genuinely hybrid approach which truly integratesthe philosophical approach and technical merits of both DES and SD in a single model. In this paperwe consider some of the reasons for this and describe two practical healthcare examples of combinedDES/SD models, which nevertheless fall short of the âholy grailâ which has been so widely discussed inthe literature over the past decade
Phase synchronization of coupled bursting neurons and the generalized Kuramoto model
Bursting neurons fire rapid sequences of action potential spikes followed by
a quiescent period. The basic dynamical mechanism of bursting is the slow
currents that modulate a fast spiking activity caused by rapid ionic currents.
Minimal models of bursting neurons must include both effects. We considered one
of these models and its relation with a generalized Kuramoto model, thanks to
the definition of a geometrical phase for bursting and a corresponding
frequency. We considered neuronal networks with different connection topologies
and investigated the transition from a non-synchronized to a partially
phase-synchronized state as the coupling strength is varied. The numerically
determined critical coupling strength value for this transition to occur is
compared with theoretical results valid for the generalized Kuramoto model.Comment: 31 pages, 5 figure
Cosmological Implications of the Fundamental Relations of X-ray Clusters
Based on the two-parameter family nature of X-ray clusters of galaxies
obtained in a separate paper, we discuss the formation history of clusters and
cosmological parameters of the universe. Utilizing the spherical collapse model
of cluster formation, and assuming that the cluster X-ray core radius is
proportional to the virial radius at the time of the cluster collapse, the
observed relations among the density, radius, and temperature of clusters imply
that cluster formation occurs in a wide range of redshift. The observed
relations favor the low-density universe. Moreover, we find that the model of
is preferable.Comment: 7 pages, 4 figures. To be published in ApJ Letter
Local Spin Glass Order in 1D
We study the behavior of one dimensional Kac spin glasses as function of the
interaction range. We verify by Montecarlo numerical simulations the crossover
from local mean field behavior to global paramagnetism. We investigate the
behavior of correlations and find that in the low temperature phase
correlations grow at a faster rate then the interaction range. We completely
characterize the growth of correlations in the vicinity of the mean-field
critical region
Complementary action of chemical and electrical synapses to perception
Acknowledgements This study was possible by partial financial support from the following agencies: Fundação AraucĂĄria, EPSRC-EP/I032606/1, CNPq No. 441553/2014-1, CAPES No. 17656-12-5 and Science Without Borders Programâ Process Nos. 17656125, 99999.010583/2013-00 and 245377/2012-3.Peer reviewedPostprin
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