Active play and sedentary behaviour in preschool children : from patterns to intervention

Physical activity (PA) and reducing the time spent sedentary can favourably impact the health and wellbeing of preschool aged children. Despite the importance of regular P A, objective monitoring studies suggest that young children do not accumulate enough P A to benefit their health. Furthermore, relatively few interventions to promote PA in children under 5 have been rigorously evaluated and intervention studies to date have generated mixed results. The aims of this thesis were to a) assess within-day variability of objectively measured moderate-to- vigorous physical activity (MVP A) during weekdays and weekend days among preschool children; b) investigate the effect of a curricular Active Play intervention on children's sedentary and P A behaviours; and, c) investigate the effect of a family focused Active Play intervention on children's weekday and weekend day sedentary time and total P A. Study 1 Background: Identifying periods of the day which are susceptible to varying levels of P A may help identify key times to intervene and potentially change preschool children's PA behaviours. This study assessed variability of objectively measured MVP A during weekdays and weekend days among preschool children. Method: One hundred and eighty-eight children (aged 3-5 years; 53.2% boys) from a northwest English city wore uni-axial accelerometers for 7 consecutive days. Results: Higher levels of MVP A were recorded in boys, particularly those who attended preschool for a half day. Children who attended preschool for a full day engaged in 11.1 minutes less MVPA than children who attended for a half day. After-school hours were characterised by a decrease in activity for all groups. Patterns of activity during the weekend were smoother with less variability. Conclusion: This study identified discrete segments of the week, specifically afterschool and during the weekend, when preschoolers engage in low levels of PA. Higher levels of MVPA among children who attended preschool for less time each day suggests that the structured preschool environment is related to decreased activity. Consequently, there is a need for interventions in young children to focus on school and home environments. - Study 2 Background: Early childhood is a critical time for the promotion of healthy lifestyle behaviours such as physical activity. Cross-sectional studies suggest that preschool children are not sufficiently active to benefit their health. Few studies have investigated the effect of interventions on physical activity levels and time spent being sedentary in this population. The aim of this study was to investigate the effect of a school-based active play intervention on preschool children's physical activity and sedentary time. Method: Two hundred and forty children were recruited from 12 randomly selected preschools in the North West of England. Six schools were randomly assigned to either an intervention (n=6) or a current practice comparison group (n=6). One teacher in each intervention school received training in the delivery of a 6-week active play programme including active play resources. The training programme was delivered by experienced active play professionals. Comparison schools received the active play resources (but not the training) and were asked to deliver their usual active play provision. Children wore a uni-axial accelerometer for 7 days at baseline, post-test and at 6 months follow up. Whole week sedentary time and physical activity adjusted for pupil- and school- level covariates were analysed using multilevel analyses. Results: No significant intervention effects were observed for sedentary time or physical activity. Sex and hours spent at school were significant predictors of physical activity in this age group, with boys engaging in less sedentary time and more light intensity activity than girls. Children who spent fewer hours at school were significantly more active than those who spent more time at school. BMI, maternal education, child's ethnicity and accelerometer wear time were not associated with activity levels. Conclusion: Physical activity during intervention classes was high. However the six teacher training intervention sessions did not increase physical activity or decrease sedentary time over a week. Specific covariates were identified as having a significant effect on the outcome measures. Moreover, children who spend more time at pre-school were less active suggesting that this setting was not as conducive to physical activity engagement as other environments. Study 3 Background: Early childhood provides a window of opportunity for the promotion of physical activity. Given the limited effectiveness of interventions to date, new approaches are needed. Socio-ecological models suggest that involving parents as intervention targets may be effective in fostering healthier lifestyles in children. This study describes the effectiveness of a family-focused' Active Play' intervention in decreasing sedentary time and increasing total physical activity in preschool children. Method: Seventy-seven families were recruited from 8 randomly selected SureStart children's centres in the North West of England. Centres were randomly assigned to either an intervention (n=4) or a comparison group (n=4). Parents and children in the - intervention group received a IOeweek active play programme delivered by trained active play professionals; this included an activity and educational component. Families in the comparison group were asked to maintain their usual routine. Each participating parent and child wore a uni-axial accelerometer for 7 days at baseline and post-test. Week and weekend day sedentary time and total physical activity adjusted for child- and home- level covariates were analysed using multilevel analyses. Results: Significant intervention effects were observed for sedentary time and physical activity for both week and weekend days. Children in the intervention group engaged in 1.5% and 4.3% less sedentary time during week and weekend days, respectively and 4.5% and 13.1 % more physical activity during week and weekend days, respectively than children in the comparison group. Parent's participation in sport and their physical activity levels, child's sex, availability of media in the home and attendance at organised activities were significant predictors of sedentary time and physical activity in this age group. Conclusion: A 10-week family focused active play intervention produced positive changes in sedentary time and total physical activity levels in preschool children. Specific covariates were identified as having a significant effect on the outcome measures. Moreover, children whose parents were active engaged in less sedentary time and more physical activity suggesting that parent's activity habits are mediators of physical activity engagement in this age group

Formation and characterization of porous InP layers in KOH Solutions

Porous InP layers were formed electrochemically on (100) oriented n-InP substrates in various concentrations of aqueous KOH under dark conditions. In KOH concentrations from 2 mol dm-3 to 5 mol dm-3, a porous layer is obtained underneath a dense near-surface layer. The pores within the porous layer appear to propagate from holes through the near-surface layer. Transmission electron microscopy studies of the porous layers formed under both potentiodynamic and potentiostatic conditions show that both the thickness of the porous layer and the mean pore diameter decrease with increasing KOH concentration. The degree of porosity, estimated to be 65%, was found to remain relatively constant for all the porous layers studied

Pressure induced anisotropy of electrical conductivity in polycrystalline molybdenum disulfide

Anisotropic specimens of MoS2 are obtained by pressing the microcrystalline powder into special die. This inelastic compression results in a rearrangement of the disulfide micro platelets observed by atomic force microscopy and reflected in the macroscopic anisotropy in electrical conductivity in these samples. The conductivity measured parallel and perpendicular to the direction of applied pressure exhibits an anisotropy factor of 10 at 1 GPa. This behaviour of the conductivity as a function of applied pressure is explained as the result of the simultaneous influence of a rearrangement of the micro platelets in the solid and the change of the inter-grain distances

Anodic oxidation of InP in KOH electrolytes

The anodic behavior of InP in 1 mol dm-3 KOH was investigated and compared with its behavior at higher concentrations of KOH. At concentrations of 2 mol dm-3 KOH or greater, selective etching of InP occurs leading to thick porous InP layers near the surface of the sustrate. In contrast, in 1 mol dm-3 KOH, no such porous layers are formed but a thin surface film is formed at potentials in the range 0.6 V to 1.3 V. The thickness of this film was determined by spectroscopic ellipsometry as a function of the upper potential and the measured film thickness corresponds to the charge passed up to a potential of 1.0 V. Anodization to potentials above 1.5 V in 1 mol dm- 3 KOH results in the growth of thick, porous oxide films (~ 1.2 µm). These films are observed to crack, ex-situ, due to shrinkage after drying in ambient air. Comparisons between the charge density and film thickness measurements indicate a porosity of approximately 77% for such films

2D nanosheet paint from solvent-exfoliated Bi2Te3 ink

Embedding 2D layered materials into polymers and other materials as composites has resulted in the development of ultrasensitive pressure sensors, tunable conductive stretchable polymers, and thermoelectric coatings. As a wettable paint or ink, many 2D materials may be penciled, printed, or coated onto a range of surfaces for a variety of applications. However, the intrinsic conductive properties of painted coatings using 2D and layered materials are not completely understood, and conductive polymer additives may mask underlying properties such as directional conductivity. We report a process for making a paint from solvent-exfoliated Bi2Te3 into solution-dispersible 2D and few-layer (multiple quintuple) nanosheet inks, that form smooth, uniform paint blends at several concentrations of Bi2Te3. The individual solvent-exfoliated nanosheets are edge-coated by (poly)ethylene glycol to produce a paint, stable over extended period in solution. Electrical transport is found to be sensitive to aspect ratio, and conduction along the painting direction is suppressed for longer strips so long as the aspect ratio is high (4–10× or more), but for short and wide paint strips (aspect ratio ≤1), conductance is improved by a factor of 3×. Square 2D paint regions show no clear directional preference for conductance at room temperature but are markedly affected by higher temperatures. Conductivity along a preferential conduction pathway through the nanosheet ensemble is modulated by 2D nanosheet stacking along the direction of paint application for a given aspect ratio. This paint and insights into geometrical 2D composite conduction may have implications for conductive composites, thermoelectrics, and writable circuits using 2D material paints or inks

Zone-plate focusing of Bose-Einstein condensates for atom optics and erasable high-speed lithography of quantum electronic components

We show that Fresnel zone plates, fabricated in a solid surface, can sharply focus atomic Bose-Einstein condensates that quantum reflect from the surface or pass through the etched holes. The focusing process compresses the condensate by orders of magnitude despite inter-atomic repulsion. Crucially, the focusing dynamics are insensitive to quantum fluctuations of the atom cloud and largely preserve the condensates' coherence, suggesting applications in passive atom-optical elements, for example zone plate lenses that focus atomic matter waves and light at the same point to strengthen their interaction. We explore transmission zone-plate focusing of alkali atoms as a route to erasable and scalable lithography of quantum electronic components in two-dimensional electron gases embedded in semiconductor nanostructures. To do this, we calculate the density profile of a two-dimensional electron gas immediately below a patch of alkali atoms deposited on the surface of the nanostructure by zone-plate focusing. Our results reveal that surface-induced polarization of only a few thousand adsorbed atoms can locally deplete the electron gas. We show that, as a result, the focused deposition of alkali atoms by existing zone plates can create quantum electronic components on the 50 nm scale, comparable to that attainable by ion beam implantation but with minimal damage to either the nanostructure or electron gas.Comment: 13 pages, 7 figure

Fabrication of p-type porous GaN on silicon and epitaxial GaN

Abstract : Porous GaN layers are grown on silicon from gold or platinum catalyst seed layers, and self-catalyzed on epitaxial GaN films on sapphire. Using a Mg-based precursor, we demonstrate p-type doping of the porous GaN. Electrical measurements for p-type GaN on Si show Ohmic and Schottky behavior from gold and platinum seeded GaN, respectively. Ohmicity is attributed to the formation of a Ga2Au intermetallic. Porous p-type GaN was also achieved on epitaxial n-GaN on sapphire, and transport measurements confirm a p-n junction commensurate with a doping density of 1018 cm 3. Photoluminescence and cathodoluminescence confirm emission from Mg-acceptors in porous p-type GaN

Feasibility of a multicentre, randomised controlled trial of laparoscopic versus open colorectal surgery in the acute setting: the LaCeS feasibility trial protocol.

Introduction Acute colorectal surgery forms a significant proportion of emergency admissions within the National Health Service. There is limited evidence to suggest minimally invasive surgery may be associated with improved clinical outcomes in this cohort of patients. Consequently, there is a need to assess the clinical effectiveness and cost-effectiveness of laparoscopic surgery in the acute colorectal setting. However,emergency colorectal surgical trials have previously been difficult to conduct due to issues surrounding recruitment and equipoise. The LaCeS (randomised controlled trial of Laparoscopic versus open Colorectal Surgery in the acute setting) feasibility trial will determine the feasibility of conducting a definitive, phase III trial of laparoscopic versus open acute colorectal resection. Methods and analysis The LaCeS feasibility trial is a prospective, multicentre, single-blinded, parallel group, pragmatic randomised controlled feasibility trial. Patients will be randomised on a 1:1 basis to receive either laparoscopic or open surgery. The trial aims to recruit at least 66 patients from five acute general surgical units across the UK. Patients over the age of 18 with a diagnosis of acute colorectal pathology requiring resection on clinical and radiological/endoscopic investigations, with a National Confidential Enquiry into Patient Outcome and Death classification of urgent will be considered eligible for participation. The primary outcome is recruitment. Secondary outcomes include assessing the safety profile of laparoscopic surgery using intraoperative and postoperative complication rates, conversion rates and patient-safety indicators as surrogate markers. Clinical and patient-reported outcomes will also be reported. The trial will contain an embedded qualitative study to assess clinician and patient acceptability of trial processes. Ethics and dissemination The LaCeS feasibility trial is approved by the Yorkshire and The Humber, Bradford Leeds Research Ethics Committee (REC reference: 15/ YH/0542). The results from the trial will be presented at national and international colorectal conferences and will be submitted for publication to peer-reviewed journals. Trial registration number ISRCTN15681041; Pre-results