  Scientific research is highly dynamic. New areas of science continually
evolve;others gain or lose importance, merge or split. Due to the steady
increase in the number of scientific publications it is hard to keep an
overview of the structure and dynamic development of one's own field of
science, much less all scientific domains. However, knowledge of hot topics,
emergent research frontiers, or change of focus in certain areas is a critical
component of resource allocation decisions in research labs, governmental
institutions, and corporations. This paper demonstrates the utilization of
Kleinberg's burst detection algorithm, co-word occurrence analysis, and graph
layout techniques to generate maps that support the identification of major
research topics and trends. The approach was applied to analyze and map the
complete set of papers published in the Proceedings of the National Academy of
Sciences (PNAS) in the years 1982-2001. Six domain experts examined and
commented on the resulting maps in an attempt to reconstruct the evolution of
major research areas covered by PNAS.
