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- Infectious disease (2)
- Clustering (1)
- Connectivity (1)
- Conserved energy (1)
- Disordered media (1)
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- Driven dynamical systems (1)
- Dynamical evolution (1)
- Epidemic dynamics (1)
- Forest-fire model (1)
- Information dissemination (1)
- Journal articles (1)
- Networks (1)
- Phase transition (1)
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- Sandpile models (1)
- Scale-free networks (1)
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Articles 1 - 7 of 7
Full-Text Articles in Physical Sciences and Mathematics
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.
Modeling The Evolution Of Weighted Networks, A Barrat, M Barthelemy, A Vespignani
Modeling The Evolution Of Weighted Networks, A Barrat, M Barthelemy, A Vespignani
Alessandro Vespignani
We present a general model for the growth of weighted networks in which the structural growth is coupled with the edges' weight dynamical evolution. The model is based on a simple weight-driven dynamics and a weights' reinforcement mechanism coupled to the local network growth. That coupling can be generalized in order to include the effect of additional randomness and nonlinearities which can be present in real-world networks. The model generates weighted graphs exhibiting the statistical properties observed in several real-world systems. In particular, the model yields a nontrivial time evolution of vertices' properties and scale-free behavior with exponents depending on …
Energy Constrained Sandpile Models, A Chessa, E Marinari, A Vespignani
Energy Constrained Sandpile Models, A Chessa, E Marinari, A Vespignani
Alessandro Vespignani
We study two driven dynamical systems with conserved energy. The two automata contain the basic dynamical rules of the Bak, Tang, and Wiesenfeld sandpile model. In addition a global constraint on the energy contained in the lattice is imposed. In the limit of an infinitely slow driving of the system, the conserved energy E becomes the only parameter governing the dynamical behavior of the system. Both models show scale-fret behavior at a critical value E-c of the fixed energy. The scaling with respect to the relevant scaling field points out that the developing of critical correlations is in a different …
First-Order Transition In The Breakdown Of Disordered Media, S Zapperi, P Ray, H Stanley, A Vespignani
First-Order Transition In The Breakdown Of Disordered Media, S Zapperi, P Ray, H Stanley, A Vespignani
Alessandro Vespignani
We study the approach to global breakdown in disordered media driven by increasing external forces. We first analyze the problem by mean-field theory, showing that the failure process can be described as a first-order phase transition, similarly to the case of thermally activated fracture in homogeneous media. Then we quantitatively confirm the predictions of the mean-field theory using numerical simulations of discrete models. Widely distributed avalanches and the corresponding mean-field scaling are explained by the long-range nature of elastic interactions. We discuss the analogy of our results to driven disordered first-order transitions and spinodal nucleation in magnetic systems.
Diffusion Of Scientific Credits And The Ranking Of Scientists, Filippo Radicchi, Santo Fortunato, Benjamin Markines, Alessandro Vespignani
Diffusion Of Scientific Credits And The Ranking Of Scientists, Filippo Radicchi, Santo Fortunato, Benjamin Markines, Alessandro Vespignani
Alessandro Vespignani
Recently, the abundance of digital data is enabling the implementation of graph-based ranking algorithms that provide system level analysis for ranking publications and authors. Here, we take advantage of the entire Physical Review publication archive (1893-2006) to construct authors' networks where weighted edges, as measured from opportunely normalized citation counts, define a proxy for the mechanism of scientific credit transfer. On this network, we define a ranking method based on a diffusion algorithm that mimics the spreading of scientific credits on the network. We compare the results obtained with our algorithm with those obtained by local measures such as the …
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. …
Corrections To Scaling In The Forest-Fire Model, R Pastor-Satorras, A Vespignani
Corrections To Scaling In The Forest-Fire Model, R Pastor-Satorras, A Vespignani
Alessandro Vespignani
We present a systematic study of corrections to scaling in the self-organized critical forest-fire model. The analysis of the steady-state condition for the density of trees allows us to pinpoint the presence of these corrections, which take the form of subdominant exponents modifying the standard finite-size scaling form. Applying an extended version of the moment analysis technique, we find the scaling region of the model and compute nontrivial corrections to scaling.