Contents

This is a final report of a project. It has been formally reviewed but has not been formally edited. RAND is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions or policies of its research sponsors. Photos on the cover appear courtesy of Monsanto.com, the Jet Propulsion Laboratory and the United Nations Photo Library (#UN205371). © Copyright 2001 RAND All rights reserved. No part of this book may be reproduced in any form by any electronic or mechanical means (including photocopying, recording, or information storage and retrieval) without permission in writing from RAND. Published 2001 by RAN