This material is based upon work supported by the National Science
Foundation under Grant No.IIS-9812755 and the Air Force Research Laboratory/IFTD
and the Defense Advanced Research Projects Agency under
Contract F30602-99-2-0525. The U.S. Government is authorized to reproduce
and distribute reprints for Governmental purposes not withstanding any copyright
annotation thereon. Disclaimer: The views and conclusions contained
herein are those of the authors and should not be interpreted as necessarily
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of the Defense Advanced Research Projects Agency, Air Force Research
Laboratory/IFTD, National Science Foundation, or the U.S. Government