About the Authors

David Frigola
Laura Casanellas
José M. Sancho
Marta Ibañes

mibanes@ub.edu

Affiliation Department of Estructura i Constituents de la Matèria, Facultat de Fsica, Universitat de Barcelona, Barcelona, Spain

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: MI. Performed the experiments: DF LC. Analyzed the data: DF LC JMS MI. Contributed reagents/materials/analysis tools: DF. Wrote the paper: DF JMS MI.