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Full-Text Articles in Physics
Efficiency And Reliability Of Epidemic Data Dissemination In Complex Networks, Y Moreno, M Nekovee, A Vespignani
Efficiency And Reliability Of Epidemic Data Dissemination In Complex Networks, Y Moreno, M Nekovee, A Vespignani
Alessandro Vespignani
We study the dynamics of epidemic spreading processes aimed at spontaneous dissemination of information updates in populations with complex connectivity patterns. The influence of the topological structure of the network in these processes is studied by analyzing the behavior of several global parameters, such as reliability, efficiency, and load. Large-scale numerical simulations of update-spreading processes show that while networks with homogeneous connectivity patterns permit a higher reliability, scale-free topologies allow for a better efficiency.
Immunization Of Complex Networks, R Pastor-Satorras, A Vespignani
Immunization Of Complex Networks, R Pastor-Satorras, A Vespignani
Alessandro Vespignani
Complex networks such as the sexual partnership web or the Internet often show a high degree of redundancy and heterogeneity in their connectivity properties. This peculiar connectivity provides an ideal environment for the spreading of infective agents. Here we show that the random uniform immunization of individuals does not lead to the eradication of infections in all complex networks. Namely, networks with scale-free properties do not acquire global immunity from major epidemic outbreaks even in the presence of unrealistically high densities of randomly immunized individuals. The absence of any critical immunization threshold is due to the unbounded connectivity fluctuations of …
Invasion Threshold In Heterogeneous Metapopulation Networks, Vittoria Colizza, Alessandro Vespignani
Invasion Threshold In Heterogeneous Metapopulation Networks, Vittoria Colizza, Alessandro Vespignani
Alessandro Vespignani
We study the dynamics of epidemic and reaction-diffusion processes in metapopulation models with heterogeneous connectivity patterns. In susceptible-infected-removed-like processes, along with the standard local epidemic threshold, the system exhibits a global invasion threshold. We provide an explicit expression of the threshold that sets a critical value of the diffusion/mobility rate below, which the epidemic is not able to spread to a macroscopic fraction of subpopulations. The invasion threshold is found to be affected by the topological fluctuations of the metapopulation network. The results presented provide a general framework for the understanding of the effect of travel restrictions in epidemic containment.
Epidemic Dynamics In Finite Size Scale-Free Networks, R Pastor-Satorras, A Vespignani
Epidemic Dynamics In Finite Size Scale-Free Networks, R Pastor-Satorras, A Vespignani
Alessandro Vespignani
Many real networks present a bounded scale-free behavior with a connectivity cutoff due to physical constraints or a finite network size. We study epidemic dynamics in bounded scale-free networks with soft and hard connectivity cutoffs. The finite size effects introduced by the cutoff induce an epidemic threshold that approaches zero at increasing sizes. The induced epidemic threshold is very small even at a relatively small cutoff, showing that the neglection of connectivity fluctuations in bounded scale-free networks leads to a strong overestimation of the epidemic threshold. We provide the expression for the infection prevalence and discuss its finite size corrections. …
Absence Of Epidemic Threshold In Scale-Free Networks With Degree Correlations, M Boguna, R Pastor-Satorras, A Vespignani
Absence Of Epidemic Threshold In Scale-Free Networks With Degree Correlations, M Boguna, R Pastor-Satorras, A Vespignani
Alessandro Vespignani
Random scale-free networks have the peculiar property of being prone to the spreading of infections. Here we provide for the susceptible-infected-susceptible model an exact result showing that a scale-free degree distribution with diverging second moment is a sufficient condition to have null epidemic threshold in unstructured networks with either assortative or disassortative mixing. Degree correlations result therefore irrelevant for the epidemic spreading picture in these scale-free networks. The present result is related to the divergence of the average nearest neighbor's degree, enforced by the degree detailed balance condition.
Velocity And Hierarchical Spread Of Epidemic Outbreaks In Scale-Free Networks, M Barthelemy, A Barrat, R Pastor-Satorras, A Vespignani
Velocity And Hierarchical Spread Of Epidemic Outbreaks In Scale-Free Networks, M Barthelemy, A Barrat, R Pastor-Satorras, A Vespignani
Alessandro Vespignani
We study the effect of the connectivity pattern of complex networks on the propagation dynamics of epidemics. The growth time scale of outbreaks is inversely proportional to the network degree fluctuations, signaling that epidemics spread almost instantaneously in networks with scale-free degree distributions. This feature is associated with an epidemic propagation that follows a precise hierarchical dynamics. Once the highly connected hubs are reached, the infection pervades the network in a progressive cascade across smaller degree classes. The present results are relevant for the development of adaptive containment strategies.