Emergence of biotechnology clusters: How prior structure affects formation of technology connections in Boston and San Diego from 1979 to 2006

We explore the network structure of technology in biotechnology industrial clusters and how prior structure affects formation of ties among technologies from a network perspective. We select Boston and San Diego as cases. Based on visualization techniques of networks, we find both clusters have a separate components structure pattern. We also observe a phenomenon of boom and decline of technologies during the evolution process. We use network degree and Pagerank algorithm to measure the importance of patents (technologies as sources), betweenness centrality, and structural holes to measure the ability of technology diffusion (technologies as conduits) in prior structure. Networks of technology connections are indicated by medical patent citations in Boston and San Diego from 1976 to 2006. We find that core position of global network has a positive relation with formation of ties. Effects of bridge position are different in two clusters.