532,475 research outputs found
Effect of Unfolding on the Spectral Statistics of Adjacency Matrices of Complex Networks
Random matrix theory is finding an increasing number of applications in the
context of information theory and communication systems, especially in studying
the properties of complex networks. Such properties include short-term and
long-term correlation. We study the spectral fluctuations of the adjacency of
networks using random-matrix theory. We consider the influence of the spectral
unfolding, which is a necessary procedure to remove the secular properties of
the spectrum, on different spectral statistics. We find that, while the spacing
distribution of the eigenvalues shows little sensitivity to the unfolding
method used, the spectral rigidity has greater sensitivity to unfolding.Comment: Complex Adaptive Systems Conference 201
Stimulus sensitivity of a spiking neural network model
Some recent papers relate the criticality of complex systems to their maximal
capacity of information processing. In the present paper, we consider high
dimensional point processes, known as age-dependent Hawkes processes, which
have been used to model spiking neural networks. Using mean-field
approximation, the response of the network to a stimulus is computed and we
provide a notion of stimulus sensitivity. It appears that the maximal
sensitivity is achieved in the sub-critical regime, yet almost critical for a
range of biologically relevant parameters
Insights into the behaviour of systems biology models from dynamic sensitivity and identifiability analysis: a case study of an NF-kB signaling pathway
Mathematical modelling offers a variety of useful techniques to help in understanding the intrinsic behaviour of complex signal transduction networks. From the system engineering point of view, the dynamics of metabolic and signal transduction models can always be described by nonlinear ordinary differential equations (ODEs) following mass balance principles. Based on the state-space formulation, many methods from the area of automatic control can conveniently be applied to the modelling, analysis and design of cell networks. In the present study, dynamic sensitivity analysis is performed on a model of the IB-NF-B signal pathway system. Univariate analysis of the Euclidean-form overall sensitivities shows that only 8 out of the 64 parameters in the model have major influence on the nuclear NF-B oscillations. The sensitivity matrix is then used to address correlation analysis, identifiability assessment and measurement set selection within the framework of least squares estimation and multivariate analysis. It is shown that certain pairs of parameters are exactly or highly correlated to each other in terms of their effects on the measured variables. The experimental design strategy provides guidance on which proteins should best be considered for measurement such that the unknown parameters can be estimated with the best statistical precision. The whole analysis scheme we describe provides efficient parameter estimation techniques for complex cell networks
Structural Changes in Data Communication in Wireless Sensor Networks
Wireless sensor networks are an important technology for making distributed
autonomous measures in hostile or inaccessible environments. Among the
challenges they pose, the way data travel among them is a relevant issue since
their structure is quite dynamic. The operational topology of such devices can
often be described by complex networks. In this work, we assess the variation
of measures commonly employed in the complex networks literature applied to
wireless sensor networks. Four data communication strategies were considered:
geometric, random, small-world, and scale-free models, along with the shortest
path length measure. The sensitivity of this measure was analyzed with respect
to the following perturbations: insertion and removal of nodes in the geometric
strategy; and insertion, removal and rewiring of links in the other models. The
assessment was performed using the normalized Kullback-Leibler divergence and
Hellinger distance quantifiers, both deriving from the Information Theory
framework. The results reveal that the shortest path length is sensitive to
perturbations.Comment: 12 pages, 4 figures, Central European Journal of Physic
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