Click the image to expand the dynamic gif. This was the early visualization by (Doug July 2000) that led the way to later more detailed images from Jason's http://www-personal.umich.edu/~jdos/paj_mov.html visual analyses with Pajek. Statistical analysis on partner choice from year to year was done with McFadden's conditional logit, implemented in Matlab.
2005 Network Dynamics and Field Evolution: The Growth of Interorganizational Collaboration in the Life Sciences. (Walter W. Powell, Douglas R. White, Ken W. Koput & Jason Owen-Smith) American Journal of Sociology 110(4):901-975. - AJS enhanced text and PDF. Viviana Zelizer Best Paper in Economic Sociology Award (2005-2006), American Sociological Association. http://www.journals.uchicago.edu/AJS/journal/contents/v110n4.html
2005 Network Dynamics and Field Evolution: The Growth of Interorganizational Collaboration in the Life Sciences. (W. W. Powell, drw, K. W. Koput & J. Owen-Smith)
Barabási in [ http://www.nd.edu/~networks/Linked/newfile18.htm The Fourteenth Link: Network Economy] of Linked (2002), cites the poser-law characteristics of the distributions of number of partners but omits to report that a main result of the study of link formation was not attachment to hubs by degree, but to structural cohesion, partners higher in the structurally cohesive core of the partnership network. Those in that core, however, reach out to recruit new entrants bringing new skills, knowledge, and technologies from outside the core.