Figure 5

Time evolution of clusters in the APS citation network.

In (a) we selected all the clusters that have at least one of the keywords Criticality, Fractal, Ising, Network and Renormalization among the top 15 most frequent words appearing in the title of the papers, while in (b) we just filtered the keyword Network(s). Both diagrams were obtained using Infomap on snapshots spanning each a window of 5 years, except at the right end of each diagram: since there is no data after 2008, the last windows must have 2008 as upper limit, so their size shrinks (2004 – 2008, 2005 – 2008, 2006 – 2008, 2007 – 2008). Consensus is computed by combining pairs of consecutive snapshots (see Methods). A color uniquely identifies a module, while the width of the links between clusters is proportional to the number of papers they have in common. In (b) we observe the rapid growth of the field Complex Networks, which eventually splits in a number of smaller subtopics, like Community Structure, Epidemic Spreading, Robustness, etc..