About the Authors

Lingyun Zhao

Affiliation Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, P.R. China

Li Zhaoping


Affiliation Department of Computer Science, University College London, London, United Kingdom

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: L. Zhao, L. Zhaoping. Performed the experiments: L. Zhao, L. Zhaoping. Analyzed the data: L. Zhao, L. Zhaoping. Wrote the paper: L. Zhao, L. Zhaoping. Began the project as a course project: L. Zhao. Supervised and completed the project: L. Zhaoping.