Geographical effects on cascading breakdowns of scale-free networks
  Cascading breakdowns of real networks are severe accidents in recent years, such as the blackouts of the power transportation networks in North America. In this paper, we study the effects of geographical structure on the cascading phenomena of load-carried scale-free networks, find that more geographically constrained networks tend to have larger cascading breakdowns. Explanations by the effects of circles and large betweenness of small degree nodes are provided. 
Liang Huang, Lei Yang and Kongqing Yang