Catherine T. Lawson

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INTRODUCTION Driven largely by international declines in rates of walking and bicycling to school and the noted health benefits of physical activity for children, research on children's active commuting to school has expanded rapidly during the past 5 years. We summarize research on predictors and health consequences of active commuting to school and(More)
BACKGROUND Many youth today are physically inactive. Recent attention linking the physical or built environment to physical activity in adults suggests an investigation into the relationship between the built environment and physical activity in children could guide appropriate intervention strategies. METHOD Thirty three quantitative studies that(More)
GPS-equipped mobile devices such as smart phones and in-car navigation units are collecting enormous amounts spatial and temporal information that traces a moving object's path. The popularity of these devices has led to an exponential increase in the amount of GPS trajectory data generated. The size of this data makes it difficult to transmit it over a(More)
0198-9715/$ see front matter 2011 Elsevier Ltd. A doi:10.1016/j.compenvurbsys.2011.05.003 ⇑ Corresponding author. Tel.: +1 212 772 4658; fax E-mail address: gong@hunter.cuny.edu (H. Gong). 1 Present address: MTA Bus Company, Metropolitan Broadway, New York, NY 10004, United States. Handheld GPS provides a new technology to trace people’s daily travels and(More)
GPS-equipped mobile devices such as smart phones and in-car navigation units are collecting enormous amounts of spatial and temporal information that traces a moving object’s path. The exponential increase in the amount of such trajectory data has caused three major problems. First, transmission of large amounts of data is expensive and time-consuming.(More)
The massive volumes of trajectory data generated by inexpensive GPS devices have led to difficulties in processing, querying, transmitting and storing such data. To overcome these difficulties, a number of algorithms for compressing trajectory data have been proposed. These algorithms try to reduce the size of trajectory data, while preserving the quality(More)
With the development of web technology and mobile technology, developers are trying to provide transit information on the Internet or smartphones. In this situation, open transit data with a unified format of schedules and geographic information, such as the General Transit Feed Specification (GTFS), is required. With latitude and longitude data of transit(More)
The massive volumes of trajectory data generated by inexpensive GPS devices have led to difficulties in processing, querying, transmitting and storing such data. To overcome these difficulties, a number of algorithms for compressing trajectory data have been proposed. These algorithms try to reduce the size of trajectory data, while preserving the quality(More)
The recent increase in the use of GPS-enabled devices has introduced a new demand for efficiently storing trajectory data. In this paper, we present a new technique that has a higher compression ratio for trajectory data than existing solutions. This technique splits trajectories into sub-trajectories according to the similarities among them. For each(More)
Trajectory compression algorithms eliminate redundant information in the history of a moving object. Such compression enables efficient transmission, storage, and processing of trajectory data. Although a number of compression algorithms have been proposed in the literature, no common benchmarking platform for evaluating their effectiveness exists. This(More)