Concurrent validity of the Microsoft Kinect for assessment of spatiotemporal gait variables

Spatiotemporal characteristics of gait such as step time and length are often associated with overall physical function in clinical populations, but can be difficult, time consuming and obtrusive to measure. This study assessed the concurrent validity of overground walking spatiotemporal data recorded using a criterion reference – a marker-based three-dimensional motion analysis (3DMA) system – and a low-cost, markerless alternative, the automated skeleton tracking output from the Microsoft Kinect™ (Kinect). Twenty-one healthy adults performed normal walking trials while being monitored using both systems. The outcome measures of gait speed, step length and time, stride length and time and peak foot swing velocity were derived using supervised automated analysis. To assess the agreement between the Kinect and 3DMA devices, Bland–Altman 95% bias and limits of agreement, percentage error, relative agreement (Pearson's correlation coefficients: r) overall agreement (concordance correlation coefficients: r_c) and landmark location linearity as a function of distance from the sensor were determined. Gait speed, step length and stride length from the two devices possessed excellent agreement (r and r_c values >0.90). Foot swing velocity possessed excellent relative (r=0.93) but only modest overall (r_c=0.54) agreement. Step time (r=0.82 and r_c=0.23) and stride time (r=0.69 and r_c=0.14) possessed excellent and modest relative agreement respectively but poor overall agreement. Landmark location linearity was excellent (R²=0.991). This widely available, low-cost and portable system could provide clinicians with significant advantages for assessing some spatiotemporal gait parameters. However, caution must be taken when choosing outcome variables as some commonly reported variables cannot be accurately measured.     

Water footprint assessment for service sector: A case study of gaming industry in water scarce Macao

Although numerous studies have been carried out to investigate the water footprint of different economies at global, national and regional scales, the research on water footprint of individual economic sector, which is the elementary part of each economy, is still lacking. To fill the gap, this paper for the first time employs a hybrid method to evaluate the water footprint of gaming industry in water scarce Macao, based on the latest statistics and most exhaustive embodied water intensity databases. The results show that direct water use only accounts for extremely small fraction of the gaming industry's water footprint, indicating that the exchange of water embodied in product and service between different sectors is also a useful mean to satisfy individual sector's demand for water resources. As Macao's demand for water is growing, integrated plans including economic instruments and measures like reducing the scale of commission input and promoting efficiency would ease Macao's water pressure. Water footprint assessment in this study brings along new perspectives on gaming industry's water management and encourages wise use of goods, materials and services in a sustainable way.