1. Department of Electrical and Computer Engineering, University of Washington, 185 E Stevens Way NE, Seattle, WA 98195, USA.
2. Centre for Respiratory Diseases Research, Kenya Medical Research Institute, Mbagathi Rd, Nairobi 610101, Kenya.
3. Department of Medicine, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195, USA.
4. Paul G. Allen School of Computer Science and Engineering, University of Washington, 185 E Stevens Way NE, Seattle, WA 98195, USA.