Instead of searching all papers in the citation index database, we limited our search
to literature published in the citation data from ISI web in 2008. The initial citation
graph contains 15,708 document nodes and 17,292 citation arcs; we pruned out papers
were cited less than 3 times and the fine-tuned citation graph was built from 1,506
papers. Top ten research trends were identified by employing the factor analysis as
listed in table 1.