On June 2-3, 2008, Prof. Junshan Zhang from Arizona State University (USA) and Prof. Shuguang Cui from Texas A&M University (USA) visited our laboratory. Prof. Junshan Zhang gave a wonderful talk " Threshold Structure of Channel Aware Distributed Scheduling in Ad-Hoc Networks: An Optimal Stopping Perspective". And Prof. Shuguang Cui gave a wonderful talk "Scaling Laws of Overlaid Cognitive Radio Networks".