GLOBAL CHANGE: THE GEOLOGICAL SURVEY OF CANADA PERSPECTIVE

Geological processes are fundamental to the understanding of Global Change and the geological record provides a baseline against which to assess the nature and significance of contemporary global change (Price 1986)     

Book reviews

MIDDLE EAST AND FAR EAST, Allan S. Walker, M.D., Ch.M., F.R.A.C.P. Published by the Australian War Memorial, Canberra. Obtainable at all booksellers, price 35/‐.

UNESCO, HUMANISM AND EDUCATION IN EAST AND WEST — Published in 1953 by the United Nations. 224 pages.

THE ALTERNATIVE (a dynamic approach to our relations with Asia). By John Burton, B.A., B.Ec., Ph.D., Sydney. Morgans Publications, 1954. PP. 116.

TING HSIEN — A North China Rural Community: By Sidney D. Gamble (Institute of Pacific Relations, New York, 1954). U.S. $6.50.

ZWISCHEN BEFREIUNG UND FREIHEIT. DER SONDERFALL OSTERREICH, by Karl Gruber. Verlag Ullstein. Wien, 1953.

AMERICAN ECONOMIC POLICY TOWARDS THE PHILIPPINES: By Shirley Jenkins — With an introduction by Claude A. Buss. Published under the auspices of the American Institute of Pacific Relations by Stanford University Press, California, 1954. P. 181.

THE ORIGINS OF PRUSSIA: By F. L. Carsten—Clarendon Press. Oxford, 1954. 309 pp., 1 map. (55/6 sterling).     

Two‐regime Pattern in Human Mobility: Evidence from GPS Taxi Trajectory Data

Research on complex systems has identified various aggregate relationships in phenomena that describe these systems. Travel length has been characterized by negative power distributions. Controversy, however, exists over whether mobility patterns can be modeled in terms of a simple power law (Lévy flight model) or that more complicated power laws (exponential power law, truncated Pareto) are required. This study concentrates on two issues: testing the validity of exponential power laws and truncated Pareto distributions in urban systems to describe aggregate mobility patterns, and examining differences in mobility patterns for different travel purposes. The article describes the results of an analysis of Global Positioning System (GPS) taxi trajectory data, collected in Guangzhou, China, to identify mobility patterns in the city. The least squares statistic is used to estimate the parameters of the distribution functions. Results suggest that a fusion of functions, based on an exponential power law and a truncated Pareto distribution, represents the travel time distribution best. Moreover, the findings of this study indicate different mobility patterns to exist for different travel purposes.