These data can be used to inform a resistance management strategy that requires comprehensive information concerning malaria vector species composition in the areas of interest, and their susceptibility to the insecticides proposed for their control.

All rights reserved. No part of this publication may be reproduced in any form or by any means, without the prior written permission of the Prestressed Concrete Institute. N ineteen seventy-nine was the 25-year Silver Jubilee of the founding of the Prestressed Concrete Institute. CONTENTS Part 6-Early History of Prestressed 163 Concrete in Colorado 'Ed Thwaits is now 85 years old and fives quietly in Denver, Colorado.