Tracing Competing Paradigms - Mapping Scientific Frontiers: The Quest for Knowledge Visualization - page 219

Fig. 6.13 The visualization of the final period of the AGN case study (1996-2000). The cluster
near to the front has almost vanished and the cluster to the right has also reduced considerably.
In contrast, citations of articles in the center of the co-citation network rocketed, leading by two
evidence articles published in Nature: one is about NGC-4258 and the other is about MCG-6-30-15
with the AGN paradigm directly, it is necessary to re-focus the visualization so that
both the AGN paradigm and its competitors are both within the scope of the initial
citation data. The current AGN visualization is the first step to help us understand
the fundamental works in this paradigm because we used the terms black holes
and galaxies explicitly in data sampling. In the mass extinction case, gradualism
and catastrophism debated over more than a decade since the impact theory was
first conceived to the identification of the Chicxulub crater. In the supermassive
black hole case, the AGN paradigm is so strong that its counterparts were likely
to be under-represented in the initial visualizations. This observation highlights an
issue concerning the use of such tools. The user may want to start with a simple
visualization, learn more about a set of related topics, and gradually expand the
coverage of the visualization.
In Fig. 6.13 , the visualization of the latest period (1996-2000), the predominant
positions of two 1988 evidence articles in the front cluster have been replace by
two 1995 evidence articles. Makoto Miyoshi's team at the National Astronomical
Observatory in Japan found evidence supporting the AGN paradigm based on their
study of a nearby galaxy NGC-4258. They used a network of radio telescopes