Alan Michael Lyons

Reduced Moderate-to-Vigorous Physical Activity and Increased Sedentary Behavior Are Associated With Elevated Blood Pressure Values in Children With Cerebral Palsy

Background Children with cerebral palsy (CP) participate in reduced levels of physical activity and spend increased time in sedentary behavior. The effect of reduced activity and increased sedentary behavior on their cardiometabolic health has not been investigated. Objectives The purposes of this study were: (1) to investigate the prevalence of overweight/obesity and elevated blood pressure (BP) among a cohort of ambulatory children with CP and (2) to investigate the associations among physical activity, sedentary behavior, overweight/obesity, and BP in children with CP. Study Design This was a cross-sectional study of 90 ambulatory children, aged 6 to 17 years, with CP. Methods Body mass index (BMI), waist circumference, waist-height ratio, and BP were measured on 1 occasion. Habitual physical activity was measured by accelerometry over 7 days. Results The prevalence of overweight/obesity in the cohort was 18.9%. Twenty-two percent of the children had BP values within the hypertensive or prehypertensive range. Systolic BP was positively associated with waist circumference (β=.324, P<.05) and BMI (β=.249, P<.05). Elevated BP values were associated with reduced time in moderate-to-vigorous activity, vigorous activity, and total activity, as well as increased time in sedentary behavior. The strongest association was observed between elevated BP and vigorous activity alone (odds ratio=0.61, 95% confidence interval=0.37–0.99, P<.05). Limitations A convenience sample was recruited for this study, and it is possible that this limitation resulted in selection bias. Conclusions Despite the relatively low prevalence of overweight/obesity, a relatively high proportion of children with CP had elevated BP values. Reducing sedentary behavior and increasing habitual physical activity, particularly vigorous activity, should be primary aims of rehabilitation in order to reduce cardiometabolic disease risk in this population.

Design of Complex Structured Monolithic Heat Sinks for Enhanced Air Cooling

The design and characterization of monolithic heat sinks, which can take the form of complex structures, is reported. The designs were conceived to augment heat transport for enhanced air cooling by exploiting clearly identified physical mechanisms, i.e., by streaming the flow through a 2-D array of polygonal ducts, by introducing flow-obstacle-induced local mixing, and by exploiting hydrodynamic instabilities to sustain flow unsteadiness. Fabrication of these unconventional designs was achieved by 3-D printing plastic patterns and converting them into monolithic copper structures by investment casting. A direct simulation approach aided by analytical solutions and experimental validation was undertaken to quantify fluid flow and heat transfer parameters. This paper concludes by quantifying the performance enhancement of the proposed heat sink geometries relative to a conventional longitudinally finned heat sink. On an equal pumping power basis, finned foam and slotted hexagonal heat sinks outperform conventional parallel plate finned heat sinks. On the other hand, the parallel plate heat sinks are better for pressure drop less than 20 Pa and slotted honeycombs are better for higher pressure drops (>;20 Pa).

Broadband dual-via architectures for multilayer PCB signal injection and intra-layer transition

In this paper two transmission line architectures for intra-layer transitions in multilayer printed circuit boards (PCBs) are presented. Based on a balanced power divider and combiner concept, these can significantly improve the broadband transmission behavior for transmission rates beyond 10GB/s. The electrical performance for state-of-the-art PCBs is reviewed, and compared to the approach by means of simulations and measurements.