Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS)* at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dis semination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volumes were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 39 (thesis year 1994) a total of 13,953 thesis titles from 21 Canadian and 159 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this impor tant annual reference work. While Volume 39 reports theses submitted in 1994, on occasion, certain uni versities do report theses submitted in previous years but not reported at the time.

A study has been conducted on the changes to in-service asphalts. This study represents ongoing extensive research efforts at Purdue University to investigate the changes to in-service asphalts and to evaluate the recently developed SUPERPAVE asphalt binder specifications. During the 1985 construction season, samples from the original asphalt binders and the truck mix samples (original mixtures) were retained from a number of paving projects in Indiana. In 1992/1993, after 7 to 8 years in-service, cores from these pavements were taken. During the same period of time, distress surveys were conducted. In a later stage, six projects were selected for detailed analysis using the SUPERPAVE binder test equipment and procedures. A major interest of this research was to characterize the changes in the asphalt binders in-service and to correlate these changes with the pavement distresses, mainly: permanent deformation (rutting), fatigue cracking, and low temperature cracking. Consequently, the performance grade (PG) binder specifications could be evaluated. The SUPERPAVE binder tests and associated criteria were used to determine the high, intermediate, and low temperature characteristics (stiffness, (Pa)) of the asphalt binders tested. The results compare the relation between the conditioned (aged) asphalt binders from the Rolling Thin Film Oven (RTFO) test and the asphalt binders extracted from the original mixtures and the relation between the asphalt binders conditioned in the Pressure Aging Vessel (PAV) to the asphalt binders extracted from the in-service (field) cores. The results indicate that the current SUPERPAVE RTFO conditioning does not simulate short term aging. Similarly, the results show that the PAV aging procedure does not correspond to the aging encountered after eight years in-service.