Fig. 3.

Elitism in scientific collaborations. (A) The affiliation network exhibited the rich-club phenomenon, with ${\varphi }_{norm}\left(k\right)>1$ for high degree nodes, whereas such a behavior was not present in the PI network (the year 2010 is shown; other years give the same results). (B) The rich core for year 2010 showing the cohesive community formed by the high-degree nodes. Each edge is weighted by the frequency of the partnerships found in that year. (C) The relative size of the rich core of the affiliation network, in general, shrank with the total funding, whereas the density of partnerships among the affiliations in the rich core continued to rise with the total funding.