University of South Australia

About: University of South Australia is a education organization based out in Adelaide, South Australia, Australia. It is known for research contribution in the topics: Population & Context (language use). The organization has 10086 authors who have published 32587 publications receiving 913683 citations. The organization is also known as: The University of South Australia & UniSA.

Integrating sleep, sedentary behaviour, and physical activity research in the emerging field of time-use epidemiology: definitions, concepts, statistical methods, theoretical framework, and future directions

Abstract: Nearly 70 years of sleep, sedentary behaviour, physical activity, and time-use research has led to the recent development of time-use epidemiology. To conceptualise the emerging research field and provide a framework for its further development, this paper defines its position among established branches of science, explains its main concepts and defines associated terms, recommends suitable data analysis methods, proposes a theoretical model for future research, and identifies key research questions. Time-use epidemiology is defined as the study of determinants, incidence, distributions, and effects of health-related time-use patterns in populations, and methods for preventing unhealthy time-use patterns and achieving the optimal distribution of time for population health. As a theoretical model for future studies, this paper proposes The Framework for Viable Integrative Research in Time-Use Epidemiology (VIRTUE framework), acknowledging the compositional nature of time-use data and incorporating research on: 1) methods in time-use epidemiology; 2) outcomes of time-use composition; 3) optimal time-use balance and its prevalence in populations; 4) determinants and correlates of time-use composition; and 5) effectiveness of time-use interventions. It is likely that in total more deaths worldwide can be attributed to unhealthy time use than to smoking or obesity, potentially making it the most relevant modifiable behavioural and lifestyle risk factor of our time. We hope that governments and leading health organisations will recognise the enormous importance of healthy time use, and provide adequate support for future research in time-use epidemiology.

Stability of interfacial nanobubbles.

Abstract: Interfacial nanobubbles (INBs) on a solid surface in contact with water have drawn widespread research interest. Although several theoretical models have been proposed to explain their apparent long lifetimes, the underlying mechanism still remains in dispute. In this work, the morphological evolution of INBs was examined in air-equilibrated and partially degassed water with the use of atomic force microscopy (AFM). Our results show that (1) INBs shrank in the partially degassed water while they grew slightly in the air-equilibrated water, (2) the three-phase boundary of the INBs was pinned during the morphological evolution of the INBs. Our analyses show that (1) the lifetime of INBs was sensitive to the saturation level of dissolved gases in the surrounding water, especially when the concentration of dissolved gases was close to saturation, and (2) the pinning of the three-phase boundary could significantly slow down the kinetics of both the growth and the shrinkage of the INBs. We developed a one-dimensional version of the Epstein-Plesset model of gas diffusion to account for the effect of pinning.

Global positioning systems in the time domain: How useful a tool for intelligent vehicle-highway systems?

Abstract: Much of the research and development work in intelligent vehicle-highway systems (IVHS) relies on the availability of methods for locating and monitoring vehicles (e.g. “probe vehicles”) in real time across a road network. This paper considers the use of the global positioning system (GPS) as one method for obtaining information on the position, speed and direction of travel of vehicles. It reports the results of a series of field studies, in which real-time GPS data were compared to data collected by an instrumented vehicle, under a range of physical and traffic conditions. The field studies and consequent data analysis provide a picture of the reliability and usefulness of GPS data for traffic monitoring purposes, and hence the possibilities for the use of GPS in IVHS projects. The use of GPS receivers tailored for mobile applications, and able to provide direct observations of vehicle speed and travel direction, coupled with database management using geographic information systems (GIS) software, was found to provide a reliable and efficient system for vehicle monitoring. Field data collection under “ideal” GPS conditions indicated that accurate speed and position data were readily obtained from the GPS. Under less favourable conditions (e.g. in downtown networks), data accuracy decreased but useful information could still be obtained. In addition, the conditions and situations under which GPS data errors could be expected were noted. The finding that it is possible to relate standard GPS signal quality indicators to increased errors in speed and position provides an enhanced degree of confidence in the use of the GPS system for real-time traffic observations.