47,007 research outputs found
The structure of Inter-Urban traffic: A weighted network analysis
We study the structure of the network representing the interurban commuting
traffic of the Sardinia region, Italy, which amounts to 375 municipalities and
1,600,000 inhabitants. We use a weighted network representation where vertices
correspond to towns and the edges to the actual commuting flows among those. We
characterize quantitatively both the topological and weighted properties of the
resulting network. Interestingly, the statistical properties of commuting
traffic exhibit complex features and non-trivial relations with the underlying
topology. We characterize quantitatively the traffic backbone among large
cities and we give evidences for a very high heterogeneity of the commuter
flows around large cities. We also discuss the interplay between the
topological and dynamical properties of the network as well as their relation
with socio-demographic variables such as population and monthly income. This
analysis may be useful at various stages in environmental planning and provides
analytical tools for a wide spectrum of applications ranging from impact
evaluation to decision-making and planning support.Comment: 12 pages, 12 figures, 4 tables; 1 missing ref added and minor
revision
Identity and Fragmentation in Networks
This paper looks at the role of identity in the fragmentation of networks by incorporating the choice of commitment to identity characteristics, into a noncooperative network formation game. The Nash network will feature divisions based on identity, moreover, it will have layers of such divisions. Using the renement of strictness, I get stars of highly committed players linked together by less committed players. Next, I propose an empirical methodology to deduce which dimensions of identity cause the fragmentation of a given network. I propose a practical algorithm for the estimation and apply this to data from villages in Ghana.Identity, Network formation, Community Structure
Optimal curing policy for epidemic spreading over a community network with heterogeneous population
The design of an efficient curing policy, able to stem an epidemic process at
an affordable cost, has to account for the structure of the population contact
network supporting the contagious process. Thus, we tackle the problem of
allocating recovery resources among the population, at the lowest cost possible
to prevent the epidemic from persisting indefinitely in the network.
Specifically, we analyze a susceptible-infected-susceptible epidemic process
spreading over a weighted graph, by means of a first-order mean-field
approximation. First, we describe the influence of the contact network on the
dynamics of the epidemics among a heterogeneous population, that is possibly
divided into communities. For the case of a community network, our
investigation relies on the graph-theoretical notion of equitable partition; we
show that the epidemic threshold, a key measure of the network robustness
against epidemic spreading, can be determined using a lower-dimensional
dynamical system. Exploiting the computation of the epidemic threshold, we
determine a cost-optimal curing policy by solving a convex minimization
problem, which possesses a reduced dimension in the case of a community
network. Lastly, we consider a two-level optimal curing problem, for which an
algorithm is designed with a polynomial time complexity in the network size.Comment: to be published on Journal of Complex Network
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