19 research outputs found
Evolution of the digital society reveals balance between viral and mass media influence
Online social networks (OSNs) enable researchers to study the social universe
at a previously unattainable scale. The worldwide impact and the necessity to
sustain their rapid growth emphasize the importance to unravel the laws
governing their evolution. We present a quantitative two-parameter model which
reproduces the entire topological evolution of a quasi-isolated OSN with
unprecedented precision from the birth of the network. This allows us to
precisely gauge the fundamental macroscopic and microscopic mechanisms
involved. Our findings suggest that the coupling between the real pre-existing
underlying social structure, a viral spreading mechanism, and mass media
influence govern the evolution of OSNs. The empirical validation of our model,
on a macroscopic scale, reveals that virality is four to five times stronger
than mass media influence and, on a microscopic scale, individuals have a
higher subscription probability if invited by weaker social contacts, in
agreement with the "strength of weak ties" paradigm
Percolation in self-similar networks
We provide a simple proof that graphs in a general class of self-similar
networks have zero percolation threshold. The considered self-similar networks
include random scale-free graphs with given expected node degrees and zero
clustering, scale-free graphs with finite clustering and metric structure,
growing scale-free networks, and many real networks. The proof and the
derivation of the giant component size do not require the assumption that
networks are treelike. Our results rely only on the observation that
self-similar networks possess a hierarchy of nested subgraphs whose average
degree grows with their depth in the hierarchy. We conjecture that this
property is pivotal for percolation in networks.Comment: 4 pages, 3 figure
Epidemic spreading in complex networks with degree correlations
We review the behavior of epidemic spreading on complex networks in which
there are explicit correlations among the degrees of connected vertices.Comment: Contribution to the Proceedings of the XVIII Sitges Conference
"Statistical Mechanics of Complex Networks", eds. J.M. Rubi et, al (Springer
Verlag, Berlin, 2003
Correlations in weighted networks
We develop a statistical theory to characterize correlations in weighted
networks. We define the appropriate metrics quantifying correlations and show
that strictly uncorrelated weighted networks do not exist due to the presence
of structural constraints. We also introduce an algorithm for generating
maximally random weighted networks with arbitrary to be used as null
models. The application of our measures to real networks reveals the importance
of weights in a correct understanding and modeling of these heterogeneous
systems.Comment: 4 pages, 2 figure