Before revision:  About 60\% of multiple affiliations involve institutions from within the academic sector and international co-affiliations  often involve institutions from the United States,  Germany and the United Kingdom as well as institutions in neighboring countries .
After revision:  About 60\% of multiple affiliations involve institutions from within the academic sector and international co-affiliations often involve institutions from the United States, Germany and the United Kingdom , suggesting a core-periphery network. Network analysis also reveals a number communities of countries that are more likely to share affiliations .