800 research outputs found
Week 52 Influenza Forecast for the 2012-2013 U.S. Season
This document is another installment in a series of near real-time weekly
influenza forecasts made during the 2012-2013 influenza season. Here we present
some of the results of forecasts initiated following assimilation of
observations for Week 52 (i.e. the forecast begins December 30, 2012) for
municipalities in the United States. The forecasts were made on January 4,
2013. Results from forecasts initiated the five previous weeks (Weeks 47-51)
are also presented
Phase transition in a mean-field model for sympatric speciation
We introduce an analytical model for population dynamics with intra-specific
competition, mutation and assortative mating as basic ingredients. The set of
equations that describes the time evolution of population size in a mean-field
approximation may be decoupled. We find a phase transition leading to sympatric
speciation as a parameter that quantifies competition strength is varied. This
transition, previously found in a computational model, occurs to be of first
order.Comment: accepted for Physica
Evolutionary and Ecological Trees and Networks
Evolutionary relationships between species are usually represented in
phylogenies, i.e. evolutionary trees, which are a type of networks. The
terminal nodes of these trees represent species, which are made of individuals
and populations among which gene flow occurs. This flow can also be represented
as a network. In this paper we briefly show some properties of these complex
networks of evolutionary and ecological relationships. First, we characterize
large scale evolutionary relationships in the Tree of Life by a degree
distribution. Second, we represent genetic relationships between individuals of
a Mediterranean marine plant, Posidonia oceanica, in terms of a Minimum
Spanning Tree. Finally, relationships among plant shoots inside populations are
represented as networks of genetic similarity.Comment: 6 pages, 5 figures. To appear in Proceedings of the Medyfinol06
Conferenc
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