A prospective study examining the influence of cardiac rehabilitation on the sedentary time of highly sedentary, physically inactive patients.

OBJECTIVES: Prolonged sedentary time is recognized as a distinct health risk, and mortality risks are expected to be greatest for individuals with low exercise levels. It is unknown whether participation in exercise-based cardiac rehabilitation (CR) programs influences sedentary behaviour particularly among those patients expected to be at greatest mortality risk. This study examined the influence of CR participation on sedentary behaviour and identified the proportion and characteristics (socio-demographic and clinical) of patients who do not meet exercise recommendations and have prolonged sedentary times. METHODS: A prospective study was conducted among patients of an exercise-based CR program and assessments performed at baseline and 3 months. Physical activity and sedentary behaviour information were collected by self-report, and convergent validity was examined on an accelerometer-wearing subsample. RESULTS: Of 468 CR patients approached, 130 participants were recruited with an average sedentary time of 8hours/day. Sedentary behaviour remained consistent at follow-up (relative change= -2.4%, P=0.07) notwithstanding a greater proportion meeting exercise recommendations (relative change= 57.4%). 19.2% of participants were classified to have prolonged sedentary time and not meet exercise recommendations at baseline. No significant differences were found between the characteristics of high-risk individuals and lower risk subgroups. Findings were consistent among the accelerometer-derived subgroup and the overall sample despite poor to moderate convergent validity. CONCLUSIONS: These results suggest that the exercise-focus of CR may not reduce sedentary behaviours. Future studies are needed to determine whether sedentary behaviour-specific reduction strategies are more effective than traditional exercise-based strategies and lead to meaningful improvements in clinical outcomes.

Design of a holographic tracking module for long-range retroreflector free-space systems.

Weight reduction and low power consumption are key requirements in the next generation of unmanned aerial vehicles (UAVs). To communicate with an operator, a secured link between the UAV and a ground-based station is desirable. To realize these links, retroreflecting free-space optics is potentially attractive as it offers light weight and low complexity at the UAV. However, the base station requires a high-performance tracking module to enable a steady illumination of the UAV retroreflector. In this paper, we present the design and implementation of a tracking system, which consists of coarse tracking and holographic fine tracking modules working cooperatively. Using this system, experimental field trials were carried out by mounting a multiple-quantum-well-based modulated retroreflector on a commercial UAV. A 2 Mbps optical link was achieved with a bit error rate of ∼2×10-4 at a link range of 300 m.

The psychological and social impact of camp for children with chronic illnesses: a systematic review update.

Advances in medicine have reduced mortality among children with complex medical conditions, resulting in a growing number of young patients living with chronic illnesses. Despite an improved prognosis, these children experience significant psychosocial morbidity, such as depression and anxiety. Therapeutic summer recreation camps have been proposed as an intervention to enhance quality of life among these children. The purpose of this systematic review was to assess the psychosocial impact of camp for children with chronic illnesses. A systematic review of central databases was undertaken using key words, and a rating tool ­ the Effective Public Health Practice Project (EPHPP) Quality Assessment Tool for Quantitative Studies ­ was employed to rate methodological quality. 21 studies were included in this systematic review. Although overall methodological quality was weak, camp participation appeared to offer short-term psychosocial benefits on some parameters in children with a variety of chronic illnesses. There was some consistency in improved social outcomes, such as social interaction and acceptance. Based on the available evidence, it is premature to make robust claims regarding the psychosocial impact of camp as a therapeutic intervention. Theoretically informed camp programs, long-term follow-up, and incorporating camp-based messaging into routine hospital care,may enhance the utility of camp as a potential psychosocial intervention in paediatrics.

How active are children in Toronto? A comparison with accelerometry data from the Canadian Health Measures Survey.

INTRODUCTION: The Canadian Health Measures Survey (CHMS) is the most comprehensive direct health measures survey ever conducted in Canada. Results show that the majority of children and youth (93%) do not meet current physical activity recommendations for health. CHMS data have not yet been considered alongside an independent sample of Canadian youth; such a Canadian-context examination could support CHMS results and contribute to discussions regarding accelerometry data reduction protocols. METHODS: From 2010 to 2011, valid accelerometry data were collected on 856 children living in the Greater Toronto Area (GTA). Where possible, data presentation and analyses were aligned with the CHMS protocol such that physical activity outcomes could be compared. RESULTS: Overall, trends were similar, with some deviations likely due to contextual and sampling differences and differences in data collection/reduction protocols regarding accelerometer model selection, wear time, activity intensity thresholds and epoch. CONCLUSION: The similar trends support the notion that physical inactivity is an ongoing problem in communities across Canada.

Optical properties of a retroreflecting sheet.

The power reflection and polarization properties of a close-packed array of retroreflectors are modeled, and a commercially available sheet is measured to verify the predictions. The modeling technique is conceptually simple and applicable to a wide range of structures of this type. The close-packed sheet retroreflects over a range of angles of incidence of approximately -40 to 40 deg in both directions and returns the polarization that illuminates it largely unchanged. Predictions of returned power are within 10% for light incident within 15 deg of normal and within 20% for angles less than 20 deg. Angles of polarization rotation are predicted to within 10 deg over a similar range of input angles. The model predicts the angular aperture of the sheet and the major features of the angular response. Future research will focus on design of structures with wider angles of acceptance and responses optimized for specific applications.

Blue-green (450-nm) upconversion Tm(3+):YLF laser.

We report an upconversion laser that is pumped by two colors-one red and one near infrared-and emits in the blue-green region.