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)     

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.     

Water Mamas among the Makushi in Guyana

Abstract

This article examines folklore concerning water spirits among the Makushi Amerindians in Guyana. Makushi accounts of spirits called ‘water mamas’—twingram or Tuenkaron in Makushi—associate these beings with white people in both past and present. The case is presented here that this folklore reflects Makushi histories and experiences of European contact, colonialism in Dutch and British Guiana, and ongoing relations with Europeans and other outsiders. The themes of abduction, enticement, capricious wealth, and exotic ‘palaces’ found in stories of water mamas relate to these histories and experiences and inscribe them into the present landscape in Guyana. In addition to describing beliefs in water mamas and examining Makushi histories of interaction with Europeans, the article begins to explore the comparative context of this folklore in relation to other beliefs in water spirits across Amazonia and beyond.