The structure of scientific collaboration networks
  We investigate the structure of scientific collaboration networks. We consider two scientists to be connected if they have authored a paper together, and construct explicit networks of such connections using data drawn from a number of databases, including MEDLINE (biomedical research), the Los Alamos e-Print Archive (physics), and NCSTRL (computer science). We show that these collaboration networks form "small worlds" in which randomly chosen pairs of scientists are typically separated by only a short path of intermediate acquaintances. We further give results for mean and distribution of numbers of collaborators of authors, demonstrate the presence of clustering in the networks, and highlight a number of apparent differences in the patterns of collaboration between the fields studied. 
M. E. J. Newman (Santa Fe Institute)