Three-dimensional femtosecond laser nanolithography of crystals

Nanostructuring hard optical crystals has so far been exclusively feasible at their surface, as stress induced crack formation and propagation has rendered high precision volume processes ineffective. We show that the inner chemical etching reactivity of a crystal can be enhanced at the nanoscale by more than five orders of magnitude by means of direct laser writing. The process allows to produce cm-scale arbitrary three-dimensional nanostructures with 100 nm feature sizes inside large crystals in absence of brittle fracture. To showcase the unique potential of the technique, we fabricate photonic structures such as sub-wavelength diffraction gratings and nanostructured optical waveguides capable of sustaining sub-wavelength propagating modes inside yttrium aluminum garnet crystals. This technique could enable the transfer of concepts from nanophotonics to the fields of solid state lasers and crystal optics.Comment: Submitted Manuscript and Supplementary Informatio

Longitudinal study of the associations between change in sedentary behavior and change in adiposity during childhood and adolescence:Gateshead Millennium Study

BACKGROUND: Sedentary time (ST) has been reported to have a range of negative health effects in adults, however, the evidence for such effects among children and adolescents is sparse. The primary aim of the study was to examine associations between changes in sedentary behavior (time and fragmentation) and changes in adiposity across childhood and adolescence. METHODS: Participants were recruited as part of the Gateshead Millennium Study. Measures were taken at age 7y (n=502), 9y (n=506), 12y (n=420) and 15y (n=306). Participants wore an ActiGraph GT1M and accelerometer epochs were 'sedentary' when recorded counts were ⩽25 counts/15 s. ST was calculated and fragmentation (SF) was assessed by calculating the number of sedentary bouts per sedentary hour. Associations of changes in ST and SF with changes in adiposity (Body Mass Index (BMI), and Fat Mass Index (FMI)) were examined using bivariate linear spline models. RESULTS: Increasing ST by 1% per year was associated with an increase in BMI of 0.08 kg/m(2)/year (95%CI: 0.06-0.10; P<0.001) and FMI of 0.15 kg/m(2)/year (0.11-0.19; P<0.001). Change in SF was associated with BMI and FMI (P<0.001). An increase of 1 bout per sedentary hour per year (i.e. sedentary time becoming more fragmented) was associated with an increase in BMI of 0.07 kg/m(2)/year (0.06-0.09; P<0.001) and an increase in FMI of 0.14 kg/m(2)/year (0.10-0.18; P<0.001) over the 8y period. However, an increase in SF between 9y-12y was associated with a 0.09 kg/m(2)/year decrease in BMI (-0.18-0.00; p=0.046) and 0.11 kg/m(2)/year decrease in FMI (-0.22-0.00; P=0.049). CONCLUSIONS: Increased ST and increased SF from 7y to 15y were associated with increased adiposity. This is the first study to show age-specific associations between change in objectively measured sedentary behaviour and adiposity after adjustment of MVPA in children and adolescents.. The study suggests that, targeting sedentary behaviour for obesity prevention may be most effective during periods in which we see large increases in ST.International Journal of Obesity accepted article preview online, 15 March 2017. doi:10.1038/ijo.2017.69

Children, parents and pets exercising together (CPET) : exploratory randomised controlled trial

Levels of physical activity (PA) in UK children are much lower than recommended and novel approaches to its promotion are needed. The Children, Parents and Pets Exercising Together (CPET) study is the first exploratory randomised controlled trial (RCT) to develop and evaluate an intervention aimed at dog-based PA promotion in families. CPET aimed to assess the feasibility, acceptability and potential efficacy of a theory-driven, family-based, dog walking intervention for 9-11 year olds

Individual and social determinants of multiple chronic disease behavioral risk factors among youth

<p>Abstract</p> <p>Background</p> <p>Behavioral risk factors are known to co-occur among youth, and to increase risks of chronic diseases morbidity and mortality later in life. However, little is known about determinants of multiple chronic disease behavioral risk factors, particularly among youth. Previous studies have been cross-sectional and carried out without a sound theoretical framework.</p> <p>Methods</p> <p>Using longitudinal data (n = 1135) from Cycle 4 (2000-2001), Cycle 5 (2002-2003) and Cycle 6 (2004-2005) of the National Longitudinal Survey of Children and Youth, a nationally representative sample of Canadian children who are followed biennially, the present study examines the influence of a set of conceptually-related individual/social distal variables (variables situated at an intermediate distance from behaviors), and individual/social ultimate variables (variables situated at an utmost distance from behaviors) on the rate of occurrence of multiple behavioral risk factors (physical inactivity, sedentary behavior, tobacco smoking, alcohol drinking, and high body mass index) in a sample of children aged 10-11 years at baseline. Multiple behavioral risk factors were assessed using a multiple risk factor score. All statistical analyses were performed using SAS, version 9.1, and SUDAAN, version 9.01.</p> <p>Results</p> <p>Multivariate longitudinal Poisson models showed that social distal variables including parental/peer smoking and peer drinking (Log-likelihood ratio (LLR) = 187.86, degrees of freedom (DF) = 8, <it>p </it>< .001), as well as individual distal variables including low self-esteem (LLR = 76.94, DF = 4, <it>p </it>< .001) increased the rate of occurrence of multiple behavioral risk factors. Individual ultimate variables including age, sex, and anxiety (LLR = 9.34, DF = 3, <it>p </it>< .05), as well as social ultimate variables including family socioeconomic status, and family structure (LLR = 10.93, DF = 5, <it>p </it>= .05) contributed minimally to the rate of co-occurrence of behavioral risk factors.</p> <p>Conclusions</p> <p>The results suggest targeting individual/social distal variables in prevention programs of multiple chronic disease behavioral risk factors among youth.</p