1. University of California,Department of Electrical and Computer Engineering,Santa Barbara,California,USA,93106
2. Raytheon BBN Technologies, 10 Moulton Street,Cambridge,Massachusetts,USA,02138
3. Microsoft Research Ltd, 21 Station Road,Cambridge,United Kingdom,CB1 2FB
4. University of Cagliari,Department of Electrical and Electronic Engineering,Via Castelfidardo,Cagliari,Italy,09123
5. Tokyo Institute of Technology,2-12-1 Ookayama,Department of Electrical and Electronic Engineering,Meguro-ku,Tokyo,Japan,152-8552