Driving down daily step counts: the impact of being driven to school on physical activity and sedentary behavior

This study investigated whether being driven to school was associated with lower weekday and weekend step counts, less active out-of-school leisure pursuits, and more sedentary behavior. Boys aged 10–13 years (n = 384) and girls aged 9–13 years (n = 500) attending 25 Australian primary schools wore a pedometer and completed a travel diary for one week. Parents and children completed surveys capturing leisure activity, screen time, and sociodemographics. Commute distance was objectively measured. Car travel was the most frequent mode of school transportation (boys: 51%, girls: 58%). After adjustment (sociodemographics, commute distance, and school clustering) children who were driven recorded fewer weekday steps than those who walked (girls: –1,393 steps p < .001, boys: –1,569 steps, p = .009) and participated in fewer active leisure activities (girls only: p = .043). There were no differences in weekend steps or screen time. Being driven to and from school is associated with less weekday pedometer-determined physical activity in 9- to 13-year-old elementary-school children. Encouraging children, especially girls, to walk to and from school (even for part of the way for those living further distances) could protect the health and well-being of those children who are insufficiently active.

Focused ion beam milling of carbon nanotube yarns and bucky-papers : correlating their internal structure with their macro-properties

Focused ion beam (FIB) milling through carbon nanotube (CNT) yarns and bucky-papers followed by scanning electron microscopy has recently emerged as a powerful tool for eliciting details of their internal structure. The internal arrangement of CNTs in bucky-papers and yarns directly affects their performance and characteristics. Consequently this information is critical for further optimisation of these structures and to tailor their properties for specific applications. This chapter describes in detail FIB milling of CNT yarns and bucky-papers and gives a range of examples where FIB milling has enabled a better understanding of how processing conditions and treatments affect the internal structure. Emphasis is placed on how FIB milling elucidates the influence of fabrication conditions on the internal arrangement of CNTs and how this influences the material's macroscopic properties.

Stable anode performance of an Sb–carbon nanocomposite in lithium-ion batteries and the effect of ball milling mode in the course of its preparation

Materials that alloy with lithium (Si, Ge, Sn, Sb, and P) are considered as alternatives to graphitic anodes in lithium-ion batteries. Their practical use is precluded by large volume changes (200–370%) during cycling. Embedding nanoparticles into carbon is being investigated as a way to tackle that, and ball milling is emerging as a technique to prepare nanocomposites with enhanced capacity and cyclic stability. Using Sb as a model system, we investigate the preparation of Sb–carbon nanocomposites using a reconfigurable ball mill. Four distinctive milling modes are compared. The structure of the composites varies depending on the mode. Frequent strong ball impacts are required for the optimal electrochemical performance of the nanocomposite. An outstanding stable capacity of 550 mA h g−1 for 250 cycles at a current rate of 230 mA g−1 is demonstrated in a thin electrode (1 mg cm−2) and a capacity of [similar]400 mA h g−1 can be retained at 1.15 A g−1. Some capacity fade is observed in a thicker electrode (2.5 mg cm−2), i.e. the performance is sensitive to mass loading. The electrochemical stability originates from the nanocomposite structure containing Sb nanoparticles (5–15 nm) dispersed in a carbon component.

Invader impact clarifies the roles of top-down and bottom-up effects on tropical snake populations

Disentangling the effects of prey limitation (bottom-up) and predation (top-down) processes on natural populations is difficult, but the perturbations introduced by an invasive species can provide pseudo-experimental evidence on this issue.