We report a puzzling pair of facts concerning the organization of science. The concentration of research output is declining at the department level but increasing at the individual level. For example, in evolutionary biology, over the period 1980 to 2000, the fraction of citation-weighted...

The recruitment of foreign scientists enhances US science through an expanded workforce but could also cause harm by displacing better connected domestic scientists, thereby reducing localized knowledge spillovers. We develop a model in which a sufficient condition for the absence of overall...

In this chapter we draw from existing literature and a range of statistics to describe economic, entrepreneurial and innovative activities in the transportation and warehousing sector of the U.S. economy. We suggest multiple avenues for future work, and argue for more research on the role of...