title: Phase lag in epidemics on a network of cities.
abstract: We study the synchronization and phase lag of fluctuations in the number of infected individuals in a network of cities between which individuals commute. The frequency and amplitude of these oscillations is known to be very well captured by the van Kampen system-size expansion, and we use this approximation to compute the complex coherence function that describes their correlation. We find that, if the infection rate differs from city to city and the coupling between them is not too strong, these oscillations are synchronized with a well-defined phase lag between cities. The analytic description of the effect is shown to be in good agreement with the results of stochastic simulations for realistic population sizes.
authors.affiliation: Centro de Física da Matéria Condensada and Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, P-1649-003 Lisboa Codex, Portugal.
authors.forename: G
authors.initials: G
authors.lastname: Rozhnova
authors.forename: A
authors.initials: A
authors.lastname: Nunes
authors.forename: A J
authors.initials: AJ
authors.lastname: McKane
mesh_terms: D002947:Cities / Q000706:statistics & numerical data*; D003141:Communicable Diseases / Q000453:epidemiology*; D004198:Disease Susceptibility; D058872:Epidemics / Q000706:statistics & numerical data*; D006801:Humans; D015233:Models, Statistical; D013997:Time Factors