Number of Publications of hESC, Other SC, and RNAi Research by Country of Authorship.

<p>The lines in the figures report the number of publications by scholars based in the U.S. and in countries with either constrained or flexible policies regarding hESC research; publications with authors from more than one country are credited to each country. The vertical axis reports the number of publications. The percentages in parentheses denote the share of total publications during the period (the shares sum to slightly less than 100% because they do not include publications from countries with no specified hESC policies: for hESC, this amounts to the exclusion of 15 publications from scholars in seven countries). The difference in the share of hESC publications from flexible versus constrained countries is significantly greater than the differences for other SC and RNAi (p<0.05).