We express our appreciation to Walt Mahoney, Ping Wu, and Charles Z. Hotz
for supervising the project and for their critical reading of this manuscript. We
thank Don Z. Zehnder, Edward Adams, Ted Haxo, Linh H. Nguyen,
Christopher H. Ng, and Susan Palmieri for their contribution in generating
QD probes and images. We also wish to acknowledge Hugh Daniels for his