  This paper introduces a suite of approaches and measures to study the impact
of co-authorship teams based on the number of publications and their citations
on a local and global scale. In particular, we present a novel weighted graph
representation that encodes coupled author-paper networks as a weighted
co-authorship graph. This weighted graph representation is applied to a dataset
that captures the emergence of a new field of science and comprises 614 papers
published by 1,036 unique authors between 1974 and 2004. In order to
characterize the properties and evolution of this field we first use four
different measures of centrality to identify the impact of authors. A global
statistical analysis is performed to characterize the distribution of paper
production and paper citations and its correlation with the co-authorship team
size. The size of co-authorship clusters over time is examined. Finally, a
novel local, author-centered measure based on entropy is applied to determine
the global evolution of the field and the identification of the contribution of
a single author's impact across all of its co-authorship relations. A
visualization of the growth of the weighted co-author network and the results
obtained from the statistical analysis indicate a drift towards a more
cooperative, global collaboration process as the main drive in the production
of scientific knowledge.

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