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arXiv 0705.2092q-bio.PEq-bio.QM
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异质连通随机网络中的SIR动力学

SIR dynamics in random networks with heterogeneous connectivity

Erik Volz

摘要:

具有特定度分布的随机网络已被提出作为人口结构的现实模型,但在随机网络中动态建模SIR型流行病的问题仍然很复杂。我解决了这个困境,显示如何SIR动态可以建模与三个非线性常微分方程的系统。该方法利用概率生成函数(PGF)的形式主义表示随机网络的度分布,并利用网络为中心的数量,如边缘的数量在一个定义明确的类别,而不是节点为中心的数量,如感染或可感染的数量。PGF提供了一种简单的方法,可以在网络和以节点为中心的变量之间进行转换,并随时确定流行病的发病率。该理论还提供了一种简单的方法来跟踪易感者或感染者之间的度分布的演变。这些方程被用来证明度分布对流行病的最终规模以及它在人群中传播的速度的巨大影响。幂律度分布被观察到产生一个几乎立即膨胀阶段,但有一个较小的最终尺寸相比,均匀度分布,如泊松。方程进行了比较,随机模拟,这表明与理论吻合良好。最后,动力学方程提供了一种确定流行阈值的替代方法,在该阈值下,大规模的流行病预计会发生,并且低于该阈值,流行病行为仅限于有限规模的爆发。

英文摘要:

Random networks with specified degree distributions have been proposed as realistic models of population structure, yet the problem of dynamically modeling SIR-type epidemics in random networks remains complex. I resolve this dilemma by showing how the SIR dynamics can be modeled with a system of three nonlinear ODE's. The method makes use of the probability generating function (PGF) formalism for representing the degree distribution of a random network and makes use of network-centric quantities such as the number of edges in a well-defined category rather than node-centric quantities such as the number of infecteds or susceptibles. The PGF provides a simple means of translating between network and node-centric variables and determining the epidemic incidence at any time. The theory also provides a simple means of tracking the evolution of the degree distribution among susceptibles or infecteds. The equations are used to demonstrate the dramatic effects that the degree distribution plays on the final size of an epidemic as well as the speed with which it spreads through the population. Power law degree distributions are observed to generate an almost immediate expansion phase yet have a smaller final size compared to homogeneous degree distributions such as the Poisson. The equations are compared to stochastic simulations, which show good agreement with the theory. Finally, the dynamic equations provide an alternative way of determining the epidemic threshold where large-scale epidemics are expected to occur, and below which epidemic behavior is limited to finite-sized outbreaks.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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