THE NATIONAL ACADEMIES PRESS
500 Fifth Street, N.W.
Washington, DC 20001
NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance.
This study was supported by the U.S. Department of Homeland Security under Award No. HSHQDC-08-C-00176. Any opinions, findings, and conclusions or recommendations contained in this document are those of the authors and do not necessarily reflect the views of the agencies that provided support for the project. Mention of trade names, commercial products, or organizations does not constitute their endorsement by the sponsoring agencies.
International Standard Book Number-13: 978-0-309-16263-0
International Standard Book Number-10: 0-309-16263-7
Cover: Cover design by Francesca Moghari
Additional copies of this report are available from the
National Academies Press,
500 Fifth Street, N.W., Lockbox 285, Washington, DC 20055; (800) 624-6242 or (202) 334-3313 (in the Washington metropolitan area); Internet http://www.nap.edu.
Copyright 2011 by the National Academy of Sciences. All rights reserved.
Printed in the United States of America.