The mapping, which was based on data from the assistance of 5,000 online volunteers, was published in a recent issue of the Proceedings of the National Academy of Sciences magazine.""A dense core of 80 or so critical nodes surrounded by an outer shell of 5,000 sparsely connected, isolated nodes that are very much dependent upon this core. Separating the core from the outer shell are approximately 15,000 peer-connected and self-sufficient nodes. Take away the core, and an interesting thing happens: about 30 percent of the nodes from the outer shell become completely cut off. . . . Three distinct regions are apparent: an inner core of highly connected nodes, an outer periphery of isolated networks, and a mantle-like mass of peer-connected nodes. The bigger the node, the more connections it has."
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