基金We wish to thank both referees for their careful review of the manuscript, and for the guidance and suggestions they gave which substantially improved the paper. MH was supported in part by NSF Awards 1217175, 1262982, and 1318480. CT was supported in part by NSF Award 1217175.
基金MH was supported in part by NSF Awards 0715146, by DOD/DTRA Award HDTRA-09-1-0036, and by NBCR. AG was supported in part by NSF Award 0715146 and by NBCR. YZ was supported in part by NSF DMS 1319110. The authors would like to thank an anonymous referee for pointing out some important subtle properties of the πk h operators as well providing various useful suggestions for technical simplifications of the proofs.
基金Supported by the Wilhelm-Sander-Stiftung （No. 2002.025.1 to JJM）, Deutsche Forschungsgemeinschaft （grants Me 2096/2-1, Na 203/6-1 and Ga 386/8-1） and the Deutsche Diabetes Gesellschaft （to JJM）ACKN0WLEDGMENTS The excellent technical assistance of Birgit Bailer and Lone Bagger is greatly acknowledged.