Calibration and comparison of accelerometer cut points in preschool children

Objective The present study aimed to develop accelerometer cut points to classify physical activities (PA) by intensity in preschoolers and to investigate discrepancies in PA levels when applying various accelerometer cut points. Methods To calibrate the accelerometer, 18 preschoolers (5.8 +/- 0.4 years) performed eleven structured activities and one free play session while wearing a GT1M ActiGraph accelerometer using 15 s epochs. The structured activities were chosen based on the direct observation system Children's Activity Rating Scale (CARS) while the criterion measure of PA intensity during free play was provided using a second-by-second observation protocol (modified CARS). Receiver Operating Characteristic (ROC) curve analyses were used to determine the accelerometer cut points. To examine the classification differences, accelerometer data of four consecutive days from 114 preschoolers (5.5 +/- 0.3 years) were classified by intensity according to previously published and the newly developed accelerometer cut points. Differences in predicted PA levels were evaluated using repeated measures ANOVA and Chi Square test. Results Cut points were identified at 373 counts/15 s for light (sensitivity: 86%; specificity: 91%; Area under ROC curve: 0.95), 585 counts/15 s for moderate (87%; 82%; 0.91) and 881 counts/15 s for vigorous PA (88%; 91%; 0.94). Further, applying various accelerometer cut points to the same data resulted in statistically and biologically significant differences in PA. Conclusions Accelerometer cut points were developed with good discriminatory power for differentiating between PA levels in preschoolers and the choice of accelerometer cut points can result in large discrepancies.

Why we should not cut P.E.

Thinking of cutting physical education? Think again. Even as we bemoan children's sedentary lifestyles, we often sacrifice school-based physical education in the name of providing more time for academics. In 2006, only 3.8 percent of elementary schools, 7.9 percent of middle schools, and 2.1 percent of high schools offered students daily physical education or its equivalent for the entire school year (Lee, Burgeson, Fulton, & Spain, 2007). We believe this marked reduction in school-based physical activity risks students' health and can't be justified on educational or ethical grounds. We'll get to the educational grounds in a moment. As to ethical reasons for keeping physical activity part of our young people's school days, consider the fact that childhood obesity is now one of the most serious health issues facing U.S. children (Ogden et al., 2006). School-based physical education programs engage students in regular physical activity and help them acquire skills and habits necessary to pursue an active lifestyle. Such programs are directly relevant to preventing obesity. Yet they are increasingly on the chopping block.

Diabetic peripheral neuropathy and retinal tissue thickness

Using retinal imaging, the nature and extent of compromise of retinal structural integrity has been characterized in individuals suffering from diabetic peripheral neuropathy. These findings extend our understanding of the pathological processes involved in diabetic neuropathy and offer novel ophthalmic approaches to the diagnosis and monitoring of this debilitating condition.

Visible photoluminescence from plasma-synthesized SiO 2-buffered SiN x films : effect of film thickness and annealing temperature

The effect of the film thickness and postannealing temperature on visible photoluminescence (PL) from Si Nx films synthesized by plasma-assisted radio frequency magnetron sputtering on Si O2 buffer layers is investigated. It is shown that strong visible PL is achieved at annealing temperatures above 650 °C. The optimum annealing temperature for the maximum PL yield strongly depends on the film thickness and varies from 800 to 1200°C. A comparative composition-structure-property analysis reveals that the PL intensity is directly related to the content of the Si-O and Si-N bonds in the Si Nx films. Therefore, sufficient oxidation and moderate nitridation of Si Nx Si O2 films during the plasma-based growth process are crucial for a strong PL yield. Excessively high annealing temperatures lead to weakened Si-N bonds in thinner Si Nx films, which eventually results in a lower PL intensity.

Cut here : reshaping the ABC

Monday’s announcement that the ABC will make 80 positions redundant is just the latest move in an enforced process of change to the public service broadcaster. It has a long way yet to run. The announcement finally put the lie to Tony Abbott’s election eve pledge, live on national television, that there would be “no cuts to the ABC or SBS”. In concert with other recent announcements, it seems clear that public broadcasting – and in particular the ABC – is squarely in the government’s sights.

Qaphqa : fresh cut 2013 Part 1

'Qaphqa' was an outdoor artwork exhibited in the forecourt of Brisbane’s Institute of Modern Art as part of Fresh Cut exhibition series. The work took the form of a three-storey-high series of stacked 'outhouses', the seat of each opening onto the cubicle below to form what the artist referred to as a 'long drop'. Assembled in untreated pine and plywood and festooned with mock-medieval ensigns and flags, the work included a flyer containing a poem by Jorge Luis Borges and was accompanied by a published catalogue.

The effect of topical adrenergic and anticholinergic agents on the choroidal thickness of young healthy adults

The human choroid is capable of rapidly changing its thickness in response to a variety of stimuli. However little is known about the role of the autonomic nervous system in the regulation of the thickness of the choroid. Therefore, we investigated the effect of topical parasympatholytic and sympathomimetic agents upon the choroidal thickness and ocular biometrics of young healthy adult subjects. Fourteen subjects (mean age 27.9 ± 4 years) participated in this randomized, single-masked, placebo-controlled study. Each subject had measurements of choroidal thickness (ChT) and ocular biometrics of their right eye taken before, and then 30 and 60 min following the administration of topical pharmacological agents. Three different drugs: 2% homatropine hydrobromide, 2.5% phenylephrine hydrochloride and a placebo (0.3% hydroxypropyl methylcellulose) were tested in all subjects; each on different days (at the same time of the day) in randomized order. Participants were masked to the pharmacological agent being used at each testing session. The instillation of 2% homatropine resulted in a small but significant increase in subfoveal ChT at 30 and 60 min after drug instillation (mean change 7 ± 3 μm and 14 ± 2 μm respectively; both p < 0.0001). The parafoveal choroid also exhibited a similar magnitude, significant increase in thickness with time after 2% homatropine (p < 0.001), with a mean change of 7 ± 0.3 μm and 13 ± 1 μm (in the region located 0.5 mm from the fovea center), 6 ± 1 μm and 12.5 ± 1 μm (1 mm from the fovea center) and 6 ± 2 μm and 12 ± 2 μm (1.5 mm from the fovea center) after 30 and 60 min respectively. Axial length decreased significantly 60 min after homatropine (p < 0.01). There were also significant changes in lens thickness (LT) and anterior chamber depth (ACD) (p < 0.05) associated with homatropine instillation. No significant changes in choroidal thickness, or ocular biometrics were found after 2.5% phenylephrine or placebo at any examination points (p > 0.05). In human subjects, significant increases in subfoveal and parafoveal choroidal thickness occurred after administration of 2% homatropine and this implies an involvement of the parasympathetic system in the control of choroidal thickness in humans.

Macular retinal layer thickness in childhood

Purpose To examine macular retinal thickness and retinal layer thickness with spectral domain optical coherence tomography (OCT) in a population of children with normal ocular health and minimal refractive errors. Methods High resolution macular OCT scans from 196 children aged from 4 to 12 years (mean age 8 ± 2 years) were analysed to determine total retinal thickness and the thickness of 6 different retinal layers across the central 5 mm of the posterior pole. Automated segmentation with manual correction was used to derive retinal thickness values. Results The mean total retinal thickness in the central 1 mm foveal zone was 255 ± 16 μm, and this increased significantly with age (mean increase of 1.8 microns per year) in childhood (p<0.001). Age-related increases in thickness of some retinal layers were also observed, with changes of highest statistical significance found in the outer retinal layers in the central foveal region (p<0.01). Significant topographical variations in thickness of each of the retinal layers were also observed (p<0.001). Conclusions Small magnitude, statistically significant increases in total retinal thickness and retinal layer thickness occur from early childhood to adolescence. The most prominent changes appear to occur in the outer retinal layers of the central fovea.

Retinal tissue thickness is reduced in diabetic peripheral neuropathy

Aim Retinal tissue integrity in relation to diabetic neuropathy is not known. The aim of this study was to investigate retinal tissue thickness in relation to diabetic peripheral neuropathy (DPN) with and without diabetic retinopathy (DR). Methods Full retinal thickness at the parafoveal and perifoveal macula and neuro-retinal thickness around the optic nerve head (ONH) and at the macula was examined using spectral domain optical coherence tomography. The eye on the hand-dominant side of 85 individuals with type 1 diabetes and 66 individuals with type 2 diabetes, with or without DR and DPN, were compared to the eyes (n=45) of age-matched non-diabetic controls. Diabetic neuropathy was defined as Neuropathy Disability Score (NDS) ≥3 on a scale of 0-10. A general linear model was used to examine the relationship between diabetic neuropathy and foveal, parafoveal and perifoveal retinal thickness and neuro-retinal thickness, in relation to DR status, age, gender, HbA1c levels and duration of diabetes. A p-value of <0.05 was considered statistically significant. Results Perifoveal retinal thickness is reduced with increasing severity of neuropathy, especially in the inferior hemisphere (p=0.004); this effect was not related to age (p=0.088). For every unit increase in NDS score, the inferior perifoveal retinal thickness reduced by 1.64 μm. Neuro-retinal thickness around the ONH decreased with increasing severity of neuropathy (p<0.014 for average and hemisphere thicknesses); for every unit increase in NDS, neuro-retinal thickness around the ONH reduced by 1.23 μm. Retinal thickness in the parafovea was increased in the absence of DR (p<0.017 for average and hemisphere thicknesses). Neuro-retinal thickness at the macula was inversely related to age alone (p<0.001). All retinal parameters, except the inferior perifovea, reduced with advancing age (p<0.007 for all). Conclusions Diabetic neuropathy is associated with changes in full retinal thickness and neuro-retinal layers. This may represent a second threat to vision integrity, in addition to the better-characterised retinopathy. This study provides new knowledge about the anatomical aspects of the retinal tissue in relation to neuropathy and retinopathy.

Eye rubbing-induced changes in intraocular pressure and corneal thickness measured at five locations, in subjects with ocular allergy

AIM To assess the effects of eye rubbing on corneal thickness (CT) and intraocular pressure (IOP) measurements obtained 0-30min after habitual eye rubbing in symptomatic patients. METHODS Measurements of IOP and CT were obtained at five locations (central, temporal, superior, nasal and inferior) before, and every 5min for 30min interval after 30s of eye rubbing, for 25 randomly selected eyes of 14 subjects with ocular allergy and 11 age-matched normals. Differences in measurements were calculated in each group [Baseline measurements minus measurements recorded at each time interval after eye rubbing (for IOP), and for each corneal location (for CT)] and comparison were then made between groups (allergic versus control) for differences in any observed effects. RESULTS Within groups, baseline mean IOPs in the allergic patient-group (14.2±3.0 mm Hg) and in the control group (13.1±1.9 mm Hg) were similar at all times, after eye rubbing (P >0.05, for all). The maximum reduction in IOP was 0.8 mm Hg in the control subjects and the maximum increase was also 0.8 mm Hg in the allergic subjects. Between groups (allergic versus control), the changes in IOP remained under 1 mm Hg at all times (P=0.2) after 30min of eye rubbing. Between 0 and 30min of CT measurements after eye rubbing, the mean central CT (CCT), inferior CT (ICT), superior CT (SCT), temporal CT (TCT) and nasal CT (NCT) did not vary significantly from baseline values in the control and allergic-subject groups (P>0.05, for both). Between both groups, changes in CT were similar at all locations (P>0.05) except for the TC which was minimally thinner by about 4.4 µm (P=0.001) in the allergic subjects than in the control subjects, 30min following 30s of eye rubbing. CONCLUSION IOP measured in allergic subjects after 30s of habitual eye rubbing was comparable with that obtained in normal subjects at all times between 0 and 30min. Although, CT in the allergic subjects were similar to those of the control subjects at all times, it varied between +10 and -7.5 µm following eye rubbing, with the temporal cornea showing consistent reductions in thickness in the subjects with allergy. However, this reduction was minimal and was considered to not be clinically relevant.

Comprehensive contribution of filament thickness and crosslinker failure to the rheological property of F-actin cytoskeleton

Rheological property of F-actin cytoskeleton is significant to the restructuring of cytoskeleton under a variety of cell activities. This study numerically validates the rheological property of F-actin cytoskeleton is not only a result of kinetic energy dissipation of F-actin, but also greatly depends on the configuration remodeling of networks structure. Both filament geometry and crosslinker properties can affect the remodeling of F-actin cytoskeleton. The crosslinker unbinding is found to dissipate energy and induce prominent stress relaxation in the F-actin adjacent to cross-linkages. Coupled with F-actin elasticity, the energy dissipation and stress relaxation are more significant in bundled F-actin networks than in single F-actin networks.

Peripapillary choroidal thickness in childhood

Changes in the thickness of the invivo peripapillary choroid have been documented in a range of ocular conditions in adults; however, choroidal thickness in the peripapillary region of children has not been examined in detail. This study therefore aimed to investigate the thickness of the peripapillary choroid and the overlying retinal nerve fibre layer (RNFL) in a population of normal children with a range of refractive errors. Ninety-three children (37 myopes and 56 non-myopes) aged between 11 and 16 years, had measurements of peripapillary choroidal and RNFL thickness derived from enhanced depth imaging optical coherence tomography images (EDI-OCT, Heidelberg Spectralis). The average thickness was determined in a series of five 0.25 mm width concentric annuli (each divided into 8 equal sized 45° sectors) centred on the optic nerve head boundary, accounting for individual ocular magnification factors and the disc-fovea angle. Significant variations in peripapillary choroidal thickness were found to occur with both annulus location (p<0.001) and sector position (p<0.001) in this population of children. The innermost annulus (closest to the edge of the optic disc) exhibited the thinnest choroid (mean 77 ± 16 μm) and the outermost annulus, the thickest choroid (191 ± 52 μm). The choroid was thinnest inferior to the optic nerve head (139 ± 38 μm) and was thickest in the superior temporal sector (157 ± 40 μm). Significant differences in the distribution of choroidal thickness were also associated with myopia, with myopic children having significantly thinner choroids in the inner and outer annuli of the nasal and temporal sectors respectively (p<0.001). RNFL thickness also varied significantly with annulus location and sector (p<0.001), and showed differences in thickness distribution associated with refractive error. This study establishes the normal variations in the thickness of the peripapillary choroid with radial distance and azimuthal angle from the optic nerve head boundary. A significant thinning of the peripapillary choroid associated with myopia in childhood was also observed in both nasal and temporal regions. The changes in peripapillary RNFL and choroidal thickness associated with refractive error are consistent with a redistribution of these tissues occurring with myopic axial elongation in childhood.

A genetic analysis of cortical thickness in 372 twins

Imaging genetics is a new field of neuroscience that blends methods from computational anatomy and quantitative genetics to identify genetic influences on brain structure and function. Here we analyzed brain MRI data from 372 young adult twins to identify cortical regions in which gray matter volume is influenced by genetic differences across subjects. Thickness maps, reconstructed from surface models of the cortical gray/white and gray/CSF interfaces, were smoothed with a 25 mm FWHM kernel and automatically parcellated into 34 regions of interest per hemisphere. In structural equation models fitted to volume values at each surface vertex, we computed components of variance due to additive genetic (A), shared (C) and unique (E) environmental factors, and tested their significance. Cortical regions in the vicinity of the perisylvian language cortex, and at the frontal and temporal poles, showed significant additive genetic variance, suggesting that volume measures from these regions may provide quantitative phenotypes to narrow the search for quantitative trait loci that influence brain structure.