1 School of Information Sciences, University of Illinois Urbana Champaign, Champaign, IL, USA. Electronic address: halil@illinois.edu.
2 Department of Electrical, Computer, and Biomedical Engineering, Toronto Metropolitan University, Toronto, ON, Canada. Electronic address: fensan@torontomu.ca.
3 Department of Computer Science, Virginia Commonwealth University, Richmond, VA, USA. Electronic address: btmcinnes@vcu.edu.
4 Information School, University of Washington, Seattle, WA, USA. Electronic address: lucylw@uw.edu.