About the Authors
UPMC Univ Paris 06, UMR 7222, ISIR, Paris, France
CNRS, UMR 7222, ISIR, Paris, France
The authors have declared that no competing interests exist.
Conceived and designed the experiments: LR EG. Performed the experiments: LR EG. Analyzed the data: LR EG. Contributed reagents/materials/analysis tools: LR EG. Wrote the paper: LR EG.