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We deploy optical microscopy with and without an applied magnetic field to characterize the three-dimensional morphology and measure the line tension of twist disclinations in twisted nematic liquid crystal (LC) sample cells. Twist disclinations are generated by quenching the LC, 5CB (4-cyano-4'-pentylbiphenyl), into the nematic phase; 5CB is confined between substrates with in-plane anchoring directions perpendicular to one another. The disclinations form loops separating domains of opposite twist handedness. Many segments of these loops are pinned to the substrates, and the ends of some pinned segments connect to free disclination segments that penetrate into the bulk nematic. We use confocal microscopy to measure the profiles of these free disclinations and test theoretical predictions about their shape, yielding a lower bound of ∼32 nm for the disclination core radius. We then use an applied magnetic field to deform the free disclinations into circular arcs whose curvature increases with magnetic field strength and depends on the field-induced energy difference between opposite twist domains. The line tension of the disclinations is derived from an energy-balance equation that relates disclination curvature to magnetic field. The measured line tension increases logarithmically with sample cell thickness; it ranges from 75 to 200 pN in samples with thickness spanning from 6 to 27 μm. In total, the investigation introduces new non-invasive methodologies for studies of defects in LCs, and it provides new information about the line tension and character of isolated twist disclinations, thereby testing theory and laying experimental foundation for the study of ensembles of disclinations.

Background: This study explored the prospective associations of genetic susceptibility to high blood pressure (BP) and muscle strength with cardiovascular disease (CVD) mortality, incident coronary heart disease (CHD) and incident stroke., Methods: This study included 349 085 white British individuals from the UK Biobank study. Genetic risk of high BP was estimated using a weighted polygenic risk score that incorporated 136 and 135 nonoverlapping single-nucleotide polymorphisms for systolic BP and diastolic BP, respectively. Muscle strength was assessed using a hand dynamometer and expressed relative to fat-free mass. Sex- and age-specific tertiles were used to classify muscle strength into three categories. Cox regressions with age as the underlying timescale were fit for CVD mortality (n = 8275), incident CHD (n = 14 503), and stroke (n = 7518)., Results: Compared with the lowest genetic risk of high BP (bottom 20%), the highest (top 20%) had greater hazards of each outcome. Low muscle strength was associated with higher hazards of CVD mortality [hazard ratio (HR): 1.51, 95% confidence interval (CI): 1.43-1.59], incident CHD (HR: 1.16, 95% CI: 1.11-1.21), and stroke (HR: 1.20, 95% CI: 1.14-1.27), independently of confounders and genetic predisposition to high BP, compared with high muscle strength. Joint analyses revealed that the estimated 10-year absolute risks of each outcome were lower for high muscle strength combined with high genetic risk, compared with low muscle strength combined with low or medium genetic risk., Conclusion: Individuals who are genetically predisposed to high BP but have high muscle strength could have lower risk of major CVD events, compared with those who have low or medium genetic risk but low muscle strength., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Objective: Adopting a physically active lifestyle and maintaining a diet rich in antioxidants can reduce the risk of vascular diseases. Arterial stiffness is an early marker for cardiovascular diseases, indicating vascular damage. This study investigates the relationship between physical activity (PA), sedentary behaviour (SB), dietary antioxidant, trace elements intake and vascular health in men and women, with a focus on pulse wave velocity (PWV), the gold standard for assessing arterial stiffness., Design: This is a nationwide population-based cross-sectional study (Observation of Cardiovascular Risk Factors in Luxembourg 2 (ORISCAV-LUX 2))., Setting: The study was conducted in Luxembourg, between November 2016 and January 2018., Participants: In total, 988 participants from the ORISCAV-LUX 2 study, who were Luxembourg residents, aged 25-79 years, underwent the required physical examination, agreed to wear an accelerometer for 1 week and presented no personal history of myocardial infarction or stroke, were included in the analysis., Primary Outcome Measure: PWV was assessed with the validated Complior instrument. Elastic-net models were used to investigate the associations of dietary intake (antioxidant and trace elements) and movement behaviours (PA and SB) with PWV in men and women., Results: The findings reveal diverse associations between PA, SB, dietary intake and PWV, with distinct patterns observed in men and women. In women, a longer median moderate-to-vigorous PA bout length (mean coefficient (β)=-0.039), a higher long-range temporal correlation (higher scaling exponent alpha) at larger time scales (>120 min; β=-1.247) and an increased intake of vitamin C (β=-1.987) and selenium (β=-0.008) were associated with lower PWV. In men, a shorter median SB bout length (β=0.019) and a lower proportion of SB time accumulated in bouts longer than 60 min (β=1.321) were associated with lower PWV. Moreover, a higher daily intake of polyphenols (β=-0.113) and selenium (β=-0.004) was associated with lower PWV in men., Conclusion: This study underscores the multifaceted nature of the associations between movement behaviours and dietary intake with PWV, as well as sex differences. These findings highlight the significance of considering both movement behaviours and dietary antioxidant intake in cardiovascular health assessments., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Traditionally, existing studies assessing the health associations of accelerometer-measured movement behaviors have been performed with few averaged values, mainly representing the duration of physical activities and sedentary behaviors. Such averaged values cannot naturally capture the complex interplay between the duration, timing, and patterns of accumulation of movement behaviors, that altogether may be codependently related to health outcomes in adults. In this study, we introduce a novel approach to visually represent recorded movement behaviors as images using original accelerometer outputs. Subsequently, we utilize these images for cluster analysis employing deep convolutional autoencoders., Methods: Our method involves converting minute-by-minute accelerometer outputs (activity counts) into a 2D image format, capturing the entire spectrum of movement behaviors performed by each participant. By utilizing convolutional autoencoders, we enable the learning of these image-based representations. Subsequently, we apply the K-means algorithm to cluster these learned representations. We used data from 1812 adult (20-65 years) participants in the National Health and Nutrition Examination Survey (NHANES, 2003-2006 cycles) study who worn a hip-worn accelerometer for 7 seven consecutive days and provided valid accelerometer data., Results: Deep convolutional autoencoders were able to learn the image representation, encompassing the entire spectrum of movement behaviors. The images were encoded into 32 latent variables, and cluster analysis based on these learned representations for the movement behavior images resulted in the identification of four distinct movement behavior profiles characterized by varying levels, timing, and patterns of accumulation of movement behaviors. After adjusting for potential covariates, the movement behavior profile characterized as "Early-morning movers" and the profile characterized as "Highest activity" both had lower levels of insulin (P < 0.01 for both), triglycerides (P < 0.05 and P < 0.01, respectively), HOMA-IR (P < 0.01 for both), and plasma glucose (P < 0.05 and P < 0.1, respectively) compared to the "Lowest activity" profile. No significant differences were observed for the "Least sedentary movers" profile compared to the "Lowest activity" profile., Conclusions: Deep learning of movement behavior profiles revealed that, in addition to duration and patterns of movement behaviors, the timing of physical activity may also be crucial for gaining additional health benefits., (© 2024. The Author(s).)

Background and Aims: Arterial stiffness predicts cardiovascular morbidity and mortality. We aimed to quantify the differences in arterial stiffness associated with reallocating time between 24-h movement behaviours., Methods: This observational cross-sectional study included Luxembourg residents aged 25-79y who each provided ≥4 valid days of triaxial accelerometry (n = 1001). Covariable adjusted compositional isotemporal substitution models were used to examine if theoretical reallocations of time between device-measured sedentariness, the sleep period, light physical activity (PA), and moderate-to-vigorous PA (MVPA) were associated with the percentage difference in carotid-femoral pulse wave velocity (cfPWV). We further investigated if replacing sedentary time accumulated in prolonged (≥30 min) with non-prolonged (<30 min) bouts was associated with arterial stiffness. The results are presented as 30 min time exchanges (β (95% confidence interval))., Results: Beneficial associations with lower cfPWV were observed when reallocating time to MVPA from the sleep period (-1.38 (-2.63 to -0.12) %), sedentary time (-1.70 (-2.76 to -0.62) %), and light PA (-2.51 (-4.55 to -0.43) %), respectively. Larger associations in the opposite direction were observed when reallocating MVPA to the same behaviours (for example, replacing MVPA with sedentary time: 2.50 (0.85-4.18) %). Replacing prolonged with non-prolonged sedentary time was not associated with cfPWV (-0.27 (-0.86 to 0.32) %). In short sleepers, reallocating sedentary time to the sleep period was favourable (-1.96 (-3.74 to -0.15) %)., Conclusions: Increasing or at least maintaining MVPA appears to be important for arterial health in adults. Extending sleep in habitually short sleepers, specifically by redistributing sedentary time, may also be important., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

We study the director configurations of nematic liquid crystal (NLC) droplets with homeotropic anchoring in a magnetic field and report observation of a magnetic-field-driven transition from a deformed radial to an axial-with-defect configuration. Magnetic-field-induced transitions in NLC droplets differ fundamentally from the traditional planar Freedericksz transition due to the spherical droplet geometry and resulting topological defect. This transition has been studied theoretically, but the director configurations and mechanism of defect evolution in an applied magnetic field have yet to be observed experimentally. To this end, we combine polarized optical microscopy with a variable electromagnet (≤1 T) for continuous observation of droplet director fields, and we employ Landau-de Gennes numerical simulations to elucidate the director configurations and first-order nature of the transition. We report a configuration transition from point defect to ring defect at a critical field, which varies inversely with droplet radius and is relatively independent of surfactant type and concentration. We also estimate anchoring strengths of commonly used surfactants at the NLC-aqueous interface.

Background: There is a considerable burden of sedentary time in European adults. We aimed to quantify the differences in adiposity and cardiometabolic health associated with theoretically exchanging sedentary time for alternative 24 h movement behaviours., Methods: This observational cross-sectional study included Luxembourg residents aged 18-79 years who each provided  ≥ 4 valid days of triaxial accelerometry (n = 1046). Covariable adjusted compositional isotemporal substitution models were used to examine if statistically replacing device-measured sedentary time with more time in the sleep period, light physical activity (PA), or moderate-to-vigorous PA (MVPA) was associated with adiposity and cardiometabolic health markers. We further investigated the cardiometabolic properties of replacing sedentary time which was accumulated in prolonged (≥ 30 min) with non-prolonged (< 30 min) bouts., Results: Replacing sedentary time with MVPA was favourably associated with adiposity, high-density lipoprotein cholesterol, fasting glucose, insulin, and clustered cardiometabolic risk. Substituting sedentary time with light PA was associated with lower total body fat, fasting insulin, and was the only time-exchange to predict lower triglycerides and a lower apolipoprotein B/A1 ratio. Exchanging sedentary time with more time in the sleep period was associated with lower fasting insulin, and with lower adiposity in short sleepers. There was no significant evidence that replacing prolonged with non-prolonged sedentary time was related to outcomes., Conclusions: Artificial time-use substitutions indicate that replacing sedentary time with MVPA is beneficially associated with the widest range of cardiometabolic risk factors. Light PA confers some additional and unique metabolic benefit. Extending sleep, by substituting sedentary time with more time in the sleep period, may lower obesity risk in short sleepers., (© 2023. The Author(s).)

Objective: The study aimed to examine sociodemographic, temporal and bedtime routine correlates of parent-reported sleep duration and timing in a biethnic sample of 18 month and 36 month old children from a disadvantaged location., Methods: Between October 2010 and September 2012, parents completed a bespoke three day sleep diary when their child was approximately 18 months ( n  = 276) and 36 months of age (n  = 262) (45.1% South Asian; 54.9% white). Parents reported their child's overnight sleep duration (h/day), the time their child fell asleep, their wake time and their child's bedtime and napping routines. Data were available at both time points for 135 children., Results: In line with previous literature, South Asian children had shorter overnight sleep duration and later sleep and wake times than white children. In both ethnic groups, children slept and woke up later on weekends, and children went to bed earlier and slept longer in winter. In white children only, napping duration was associated with overnight sleep period. No significant associations were found between napping frequency and overnight sleep duration. Based on parent-reported data, children who consistently adhered to regular bedtimes and had set times for sleeping tended to go to sleep earlier, wake earlier and have longer overnight sleep., Conclusions: The data showed parent-reported variation in sleep patterns between two ethnic groups within a single geographical and deprived area. It is important that researchers, clinicians and early years workers are considerate of cultural norms in sleep practices., (© 2023 The Authors.)

Background: Existing information about population physical activity (PA) levels and sedentary time in Luxembourg are based on self-reported data., Methods: This observational study included Luxembourg residents aged 18-79y who each provided ≥4 valid days of triaxial accelerometry in 2016-18 (n=1122). Compliance with the current international PA guideline (≥150 min moderate-to-vigorous PA (MVPA) per week, irrespective of bout length) was quantified and variability in average 24h acceleration (indicative of PA volume), awake-time PA levels, sedentary time and accumulation pattern were analysed by linear regression. Data were weighted to be nationally representative., Results: Participants spent 51% of daily time sedentary (mean (95% confidence interval (CI)): 12.1 (12.0 to 12.2) h/day), 11% in light PA (2.7 (2.6 to 2.8) h/day), 6% in MVPA (1.5 (1.4 to 1.5) h/day), and remaining time asleep (7.7 (7.6 to 7.7) h/day). Adherence to the PA guideline was high (98.1%). Average 24h acceleration and light PA were higher in women than men, but men achieved higher average accelerations across the most active periods of the day. Women performed less sedentary time and shorter sedentary bouts. Older participants (aged ≥55y) registered a lower average 24h acceleration and engaged in less MVPA, more sedentary time and longer sedentary bouts. Average 24h acceleration was higher in participants of lower educational attainment, who also performed less sedentary time, shorter bouts, and fewer bouts of prolonged sedentariness. Average 24h acceleration and levels of PA were higher in participants with standing and manual occupations than a sedentary work type, but manual workers registered lower average accelerations across the most active periods of the day. Standing and manual workers accumulated less sedentary time and fewer bouts of prolonged sedentariness than sedentary workers. Active commuting to work was associated with higher average 24h acceleration and MVPA, both of which were lower in participants of poorer self-rated health and higher weight status. Obesity was associated with less light PA, more sedentary time and longer sedentary bouts., Conclusions: Adherence to recommended PA is high in Luxembourg, but half of daily time is spent sedentary. Specific population subgroups will benefit from targeted efforts to replace sedentary time with PA., (© 2022. The Author(s).)

Background: Parameters derived from an acceleration signal, such as the time accumulated in sedentary behaviour or moderate to vigorous physical activity (MVPA), may not be sufficient to describe physical activity (PA) which is a complex behaviour. Incorporating more advanced wearable-specific indicators of PA behaviour (WIPAB) may be useful when characterising PA profiles and investigating associations with health. We investigated the associations of novel objective measures of PA behaviour with glycated haemoglobin (HbA1c) and insulin sensitivity (Quicki index)., Methods: This observational study included 1026 adults (55% women) aged 18-79y who were recruited from the general population in Luxembourg. Participants provided ≥ 4 valid days of triaxial accelerometry data which was used to derive WIPAB variables related to the activity intensity, accumulation pattern and the temporal correlation and regularity of the acceleration time series., Results: Adjusted general linear models showed that more time spent in MVPA and a higher average acceleration were both associated with a higher insulin sensitivity. More time accumulated in sedentary behaviour was associated with lower insulin sensitivity. With regard to WIPAB variables, parameters that were indicative of higher PA intensity, including a shallower intensity gradient and higher average accelerations registered during the most active 8 h and 15 min of the day, were associated with higher insulin sensitivity. Results for the power law exponent alpha, and the proportion of daily time accumulated in sedentary bouts > 60 min, indicated that activity which was characterised by long sedentary bouts was associated with lower insulin sensitivity. A greater proportion of time spent in MVPA bouts > 10 min was associated with higher insulin sensitivity. A higher scaling exponent alpha at small time scales (< 90 min), which shows greater correlation in the acceleration time series over short durations, was associated with higher insulin sensitivity. When measured over the entirety of the time series, metrics that reflected a more complex, irregular and unpredictable activity profile, such as the sample entropy, were associated with lower HbA1c levels and higher insulin sensitivity., Conclusion: Our investigation of novel WIPAB variables shows that parameters related to activity intensity, accumulation pattern, temporal correlation and regularity are associated with insulin sensitivity in an adult general population., (© 2022. The Author(s).)

Absorption measurements allow the orientational order parameter of four dyes in the lyotropic chromonic liquid crystal di-sodium cromoglycate (DSCG) to be determined. The dye order parameters are small, except for dyes that intercalate between the DSCG molecules of the rod-like assemblies. The dye order parameters decrease with increasing temperature faster than the nematic order parameter of the DSCG assemblies. For intercalating dyes, the measured dye order parameter varies with the wavelength of the measurement because both intercalated and non-intercalated dye molecules contribute. On the contrary, measurements of the dye order parameter using fluorescence are sensitive only to intercalated dye molecules and produce values that reflect the order parameter of the DSCG assemblies. Therefore, the temperature and concentration dependence of the DSCG order parameter is also explored, since data of this kind on this often-studied system are lacking. Finally, the association constant of one of the intercalating dyes with the DSCG assemblies is determined, yielding a value considerably less than what is found for the same dye with DNA.

Background: Insomnia is common and associated with adverse pregnancy and perinatal outcomes in observational studies. However, those associations could be vulnerable to residual confounding or reverse causality. Our aim was to estimate the association of insomnia with stillbirth, miscarriage, gestational diabetes (GD), hypertensive disorders of pregnancy (HDP), perinatal depression, preterm birth (PTB), and low/high offspring birthweight (LBW/HBW)., Methods and Findings: We used 2-sample mendelian randomization (MR) with 81 single-nucleotide polymorphisms (SNPs) instrumenting for a lifelong predisposition to insomnia. Our outcomes included ever experiencing stillbirth, ever experiencing miscarriage, GD, HDP, perinatal depression, PTB (gestational age <37 completed weeks), LBW (<2,500 grams), and HBW (>4,500 grams). We used data from women of European descent (N = 356,069, mean ages at delivery 25.5 to 30.0 years) from UK Biobank (UKB), FinnGen, Avon Longitudinal Study of Parents and Children (ALSPAC), Born in Bradford (BiB), and the Norwegian Mother, Father and Child Cohort (MoBa). Main MR analyses used inverse variance weighting (IVW), with weighted median and MR-Egger as sensitivity analyses. We compared MR estimates with multivariable regression of insomnia in pregnancy on outcomes in ALSPAC (N = 11,745). IVW showed evidence of an association of genetic susceptibility to insomnia with miscarriage (odds ratio (OR): 1.60, 95% confidence interval (CI): 1.18, 2.17, p = 0.002), perinatal depression (OR 3.56, 95% CI: 1.49, 8.54, p = 0.004), and LBW (OR 3.17, 95% CI: 1.69, 5.96, p < 0.001). IVW results did not support associations of insomnia with stillbirth, GD, HDP, PTB, and HBW, with wide CIs including the null. Associations of genetic susceptibility to insomnia with miscarriage, perinatal depression, and LBW were not observed in weighted median or MR-Egger analyses. Results from these sensitivity analyses were directionally consistent with IVW results for all outcomes, with the exception of GD, perinatal depression, and PTB in MR-Egger. Multivariable regression showed associations of insomnia at 18 weeks of gestation with perinatal depression (OR 2.96, 95% CI: 2.42, 3.63, p < 0.001), but not with LBW (OR 0.92, 95% CI: 0.69, 1.24, p = 0.60). Multivariable regression with miscarriage and stillbirth was not possible due to small numbers in index pregnancies. Key limitations are potential horizontal pleiotropy (particularly for perinatal depression) and low statistical power in MR, and residual confounding in multivariable regression., Conclusions: In this study, we observed some evidence in support of a possible causal relationship between genetically predicted insomnia and miscarriage, perinatal depression, and LBW. Our study also found observational evidence in support of an association between insomnia in pregnancy and perinatal depression, with no clear multivariable evidence of an association with LBW. Our findings highlight the importance of healthy sleep in women of reproductive age, though replication in larger studies, including with genetic instruments specific to insomnia in pregnancy are important., Competing Interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: KT has acted as a consultant for CHDI Foundation, and Expert Witness to the High Court in England, called by the UK Medicines and Healthcare products Regulatory Agency, defendants in a case on hormonal pregnancy tests and congenital anomalies 2021/22. DAL has received support from Medtronic LTD and Roche Diagnostics for biomarker research that is not related to the study presented in this paper. The other authors report no conflicts.

The replacement of traditional classroom desks for active-permissive desks has been tested to reduce sitting time during classes. However, their impact on other domains is still unclear. We aimed to verify the potential effects of a classroom standing desk intervention on cognitive function and academic achievement in 6th-grade students. This was a controlled trial conducted with two classes [intervention (n = 22) and control (n = 27)] from a public school in Lisbon, Portugal. The intervention was carried out for 16 weeks and consisted of multi-level actions (students, parents, and teachers) centered on the implementation of standing desks in the intervention classroom. The control group had traditional classes with no use of standing desks or any other interference/action from the research team. Pre- and post-assessments of executive functions (attention, inhibitory function, memory, and fluid intelligence) and academic achievement were obtained. No differences between groups were found at baseline. Both groups improved (time effect) academic achievement (p < 0.001), memory span (p < 0.001), and inhibitory function (p = 0.008). Group versus time interactions were observed regarding operational memory (intervention: + 18.0% and control: + 41.6%; p = 0.039) and non-verbal fluid intelligence (intervention: - 14.0% and control: + 3.9%; p = 0.017). We concluded that a 16-week classroom standing desk intervention did not improve cognitive performance or academic achievement more than the traditional sitting classes.Trial registration: ClinicalTrials.gov Identifier (NCT03137836) (date of first registration: 03/05/2017)., (© 2022. The Author(s).)

Liquid crystalline phases of matter often exhibit visually stunning patterns or textures. Mostly, these liquid crystal (LC) configurations are uniquely determined by bulk LC elasticity, surface anchoring conditions, and confinement geometry. Here, we experimentally explore defect textures of the smectic LC phase in unique confining geometries with variable curvature. We show that a complex range of director configurations can arise from a single system, depending on sample processing procedures. Specifically, we report on LC textures in Janus drops comprised of silicone oil and 8CB in its smectic-A LC phase. The Janus droplets were made in aqueous suspension using solvent-induced phase separation. After drop creation, smectic layers form in the LC compartment, but their self-assembly is frustrated by the need to accommodate both the bowl-shaped cavity geometry and homeotropic (perpendicular) anchoring conditions at boundaries. A variety of stable and metastable smectic textures arise, including focal conic domains, dislocation rings, and undulations. We experimentally characterize their stabilities and follow their spatiotemporal evolution. Overall, a range of fabrication kinetics produce very different intermediate and final states. The observations elucidate assembly mechanisms and suggest new routes for fabrication of complex soft material structures in Janus drops and other confinement geometries.

We present calculations of eigenmode energies and wave functions of both azimuthal and polar distortions of the nematic director relative to a radial hedgehog trapped in a spherical drop with a smaller concentric spherical droplet at its core. All surfaces interior to the drop have perpendicular (homeotropic) boundary conditions. We also calculate director correlation functions and their relaxation times. Of particular interest is a critical mode whose energy, with fixed Frank constants, vanishes as the ratio μ=R&#95;{2}/R&#95;{1} increases toward a critical value μ&#95;{c}, where R&#95;{2} is the radius of the drop and R&#95;{1} that of the inner droplet, and then becomes negative for μ>μ&#95;{c}. Our calculations form a basis for interpreting experimental measurements of director fluctuations relative to a radial hedgehog state in a spherical drop. We compare results with those obtained by previous investigations, which use a calculational approach different from ours, and with our experimental observations.

We report the discovery and elucidation of giant spatiotemporal orientational fluctuations in nematic liquid crystal drops with radial orientation of the nematic anisotropy axis producing a central "hedgehog" defect. We study the spatial and temporal properties of the fluctuations experimentally using polarized optical microscopy, and theoretically, by calculating the eigenspectrum of the Frank elastic free energy of a nematic drop of radius R&#95;{2}, containing a spherical central core of radius R&#95;{1} and constrained by perpendicular boundary conditions on all surfaces. We find that the hedgehog defect with radial orientation has a complex excitation spectrum with a single critical mode whose energy vanishes at a critical value μ&#95;{c} of the ratio μ=R&#95;{2}/R&#95;{1}. When μ<μ&#95;{c}, the mode has positive energy, indicating that the radial hedgehog state is stable; when μ>μ&#95;{c}, it has negative energy indicating that the radial state is unstable to the formation of a lower-energy state. This mode gives rise to the large-amplitude director fluctuations we observe near the core, for μ near μ&#95;{c}. A collapse of the experimental data corroborates model predictions for μ<μ&#95;{c} and provides an estimate of the defect core size.

Objectives: To investigate associations of bedtimes and sleep durations with adiposity levels in children and adolescents., Methods: Individual data were pooled for 12 247 children (5819 with follow-up adiposity at 2.3 ± 1.4 years post-baseline) and 3563 adolescents from 11 international studies. Associations between questionnaire-based sleep durations, bedtimes and four groups of combined bedtimes and sleep lengths (later-shorter [reference]/earlier-shorter/later-longer/earlier-longer) with measured adiposity (body mass index [BMI] and waist circumference z-scores) and weight status, were investigated., Results: In children, longer sleep durations were consistently associated with lower adiposity markers, and earlier bedtimes were related to lower BMI z-score. Compared to sleeping <10 h, longer baseline sleep duration favourably predicted Δwaist z-score in girls (≥10 and <11 h (β-coefficient (95% confidence interval [CI])): -0.06 (-0.12 to -0.01)) and boys (≥11 h: -0.10 [-0.18 to -0.01]). Combined groups that were defined by longer sleep (later-longer and earlier-longer sleep patterns) were associated with lower adiposity, and later-longer sleep favourably predicted Δwaist z-score in girls (-0.09 [-0.15 to -0.02]). In adolescents, longer sleep durations and earlier bedtimes were associated with lower BMI z-score in the whole sample, and also with lower waist z-score in boys. Combined groups that were characterized by earlier bedtimes were associated with the same outcomes. For example, earlier-shorter (-0.22 (-0.43 to -0.01) and earlier-longer (-0.16 (-0.25 to -0.06) sleep were both associated with lower BMI z-score., Conclusions: If the associations are causal, longer sleep duration and earlier bedtimes should be targeted for obesity prevention, emphasizing longer sleep for children and earlier bedtimes for adolescents., (© 2021 The Authors. Pediatric Obesity published by John Wiley & Sons Ltd on behalf of World Obesity Federation.)

Short sleep appears to elevate obesity risk in youth; however, sleep is a multidimensional construct, and few studies have investigated parameters beyond duration. The objective of this study was to investigate if sleep onset time, duration, latency and night waking frequency are independently associated with adiposity and weight status in UK adolescents. This was a cross-sectional observational study of 10,619, 13-15 years olds. Adjusted linear and logistic regressions were used to investigate associations of self-reported sleep characteristics with adiposity markers (body mass index z-score and percent body fat) and weight status. Compared with a sleep onset before 10pm, later sleep timing was associated with higher adiposity and higher likelihood of overweight and obesity in boys (after midnight, odds ratio [95% confidence interval]: 1.76 [1.19-2.60]) and girls (between 11pm and 11:59pm: 1.36 [1.17-1.65]). Sleeping ≤ 8 hr, compared with > 9-10 hr, was associated with higher odds of overweight and obesity in both sexes (boys: 1.80 [1.38-2.35]; girls: 1.38 [1.06-1.79]), and so too was sleeping > 10 hr in girls (1.31 [1.06-1.62]), indicating evidence for a U-shaped association. Also in girls, compared to a sleep latency of 16-30 min, sleep latencies ≥ 46 min were associated with higher adiposity (46-60 min, beta coefficient [95% confidence interval], percent body fat: 1.47 [0.57-2.36]) and higher likelihood of overweight and obesity (46-60 min: 1.39 [1.05-1.83]), and often as opposed to never waking in the night was associated with higher adiposity (body mass index z-score: 0.24 [0.08-0.41]; percent body fat: 1.44 [0.44-2.44]). Sleep duration and timing in both sexes, and sleep quality in girls, appear to be independently associated with adiposity and weight status in adolescence, and may be important targets for obesity prevention., (© 2021 The Author. Journal of Sleep Research published by John Wiley & Sons Ltd on behalf of European Sleep Research Society.)

In lyotropic chromonic liquid crystals (LCLCs), twist distortion of the nematic director costs much less energy than splay or bend distortion. This feature leads to novel mirror-symmetry breaking director configurations when the LCLCs are confined by interfaces or contain suspended particles. Spherical colloids in an aligned LCLC nematic phase, for example, induce chiral director perturbations ("twisted tails"). The asymmetry of rod-like particles in an aligned LCLC offer a richer set of possibilities due to their aspect ratio ( α ) and mean orientation angle (〈 θ 〉) between their long axis and the uniform far-field director. Here we report on the director configuration, equilibrium orientation, and angular diffusion of rod-like particles with planar anchoring suspended in an aligned LCLC. Video microscopy reveals, counterintuitively, that two-thirds of the rods have an angled equilibrium orientation (〈 θ 〉 ≠ 0) that decreases with increasing α , while only one-third of the rods are aligned (〈 θ 〉 = 0). Polarized optical video-microscopy and Landau-de Gennes numerical modeling demonstrate that the angled and aligned rods are accompanied by distinct chiral director configurations. Angled rods have a longitudinal mirror plane (LMP) parallel to their long axis and approximately parallel to the substrate walls. Aligned rods have a transverse and longitudinal mirror plane (TLMP), where the transverse mirror plane is perpendicular to the rod's long axis. Effectively, the small twist elastic constant of LCLCs promotes chiral director configurations that modify the natural tendency of rods to orient along the far-field director. Additional diffusion experiments confirm that rods are angularly confined with strength that depends on α .

Objectives: To investigate associations of parent-reported sleep characteristics with adiposity levels in a biethnic sample of young children., Design: A cross-sectional observational study., Setting: The Born in Bradford 1000 study, UK., Participants: Children aged approximately 18 months (n=209; 40.2% South Asian; 59.8% white) and 36 months (n=162; 40.7% South Asian; 59.3% white)., Primary and Secondary Outcome Measures: Children's body mass index (BMI) z-score, sum of two-skinfolds (triceps and subscapular) and waist circumference. Adjusted regression was used to quantify associations of sleep parameters with adiposity stratified by ethnicity and age group. The results are beta coefficients (95% CIs) and unless otherwise stated represent the difference in outcomes for every 1-hour difference in sleep parameters., Results: The average sleep onset time was markedly later in South Asian (21:26±68 min) than white children (19:41±48 min). Later sleep onset was associated with lower BMI z-score (-0.3 (-0.5 to -0.0)) and sum of two-skinfolds (-1.5 mm (-2.8 mm to -0.2 mm)) in white children aged 18 months and higher BMI z-score in South Asian children aged 36 months (0.3 (0.0-0.5)). Longer sleep duration on weekends than weekdays was associated with higher BMI z-score (0.4 (0.1-0.8)) and waist circumference (1.2 cm (0.3-2.2 cm)) in South Asian children aged 18 months, and later sleep onset on weekends than weekdays was associated with larger sum of two-skinfolds (1.7 mm (0.3-3.1 mm)) and waist circumference (1.8 cm (0.6-2.9 cm)). Going to sleep ≥20 min later on weekends than weekdays was associated with lower waist circumference in white children aged 18 months (-1.7 cm (-3.2 cm to -0.1 cm))., Conclusions: Sleep timing is associated with total and central adiposity in young children but associations differ by age group and ethnicity. Sleep onset times and regular sleep schedules may be important for obesity prevention., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY. Published by BMJ.)

Background: This study examined the joint associations of leisure time physical activity and television (TV) viewing time with the prevalence of chronic diseases among Brazilian adults., Methods: Data from the Brazilian Health Survey, a nationally representative survey conducted in 2013 (n = 60 202; ≥18 years), were used. Time spent in TV viewing and leisure physical activity, physician diagnoses of diabetes, hypertension and heart disease and information on co-variables (chronological age, education, ethnicity, candies/sweets consumption, sodium intake and tobacco smoking) were collected via interview. Descriptive statistics (mean and 95% confidence interval) and logistic regression models were used for etiological analyses., Results: Physical activity attenuated but did not eliminate the risk associated with high TV viewing for at least one chronic disease in the general population [odds ratio [OR]: 1.29 (1.11-1.50)] and among women [OR: 1.31 (1.09-1.60)], adults [OR: 1.24 (1.05-1.46)] and older adults [OR: 1.63 (1.05-2.53)]. On the other hand, physical activity eliminated the risk associated with high TV viewing for at least one chronic disease among men [OR: 1.24 (0.98-1.58)]., Conclusions: We conclude that physical activity can attenuate but not eliminate the negative effects of high TV viewing on chronic disease among subgroups of Brazilian adults., (© The Author(s) 2019. Published by Oxford University Press on behalf of Faculty of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Recent studies have shown that lyotropic nematic liquid crystals (LLCs) are exceptional in their viscoelastic behavior. In particular, LLCs display a remarkable softness to twist deformations, which may lead to chiral director configurations under achiral confinement despite the absence of intrinsic chirality. The twisted escaped radial (TER) and the twisted polar (TP) are the two representative reflection symmetry breaking director configurations in the case of cylindrical confinement with homeotropic anchoring. We demonstrate how such reflection symmetry breaking of micellar LLCs under cylindrical confinement is affected by intrinsic chirality, introduced by the addition of a chiral dopant. Similarities and differences between the effects of intrinsic chirality on the defect-free TER configuration, and on the TP configuration incorporating two half-unit twist disclination lines, are discussed. In the TP case, topological constraints facilitate stable heterochiral systems even in the presence of a small amount of chiral dopant, with unusual regions of rapidly reversing handedness between homochiral domains. At moderate dopant concentrations, the TP structure becomes homochiral. At high dopant concentrations, for which the induced cholesteric pitch is much smaller than the diameter of the capillary, the cholesteric fingerprint structure develops.

The two main classes of liquid crystals are thermotropic (containing no solvent) and lyotropic (containing solvent). Both of these classes possess the nematic phase, the most simple of liquid crystal phases with only uniaxial orientational order. For both of these classes, if the constituent molecules are chiral or if a chiral dopant is added, the preferred direction of orientation rotates in helical fashion in what is called the chiral nematic phase. Recent research has shown that because the ordering entities of the two classes are quite different (molecules versus molecular assemblies), important differences in the properties of the nematic phase can result. While thermotropic chiral nematics have been extensively examined, less is known about lyotropic chiral nematics, especially for the most ideal case, a chiral-racemic system. Furthermore, none of the lyotropic chiral-racemic studies has included lyotropic chromonic liquid crystals, which are solutions of dyes, drugs, and nucleic acids. Inverse pitch measurements are reported for a chiral-racemic system of a chromonic liquid crystal across the entire chiral fraction range and over a 30 °C temperature interval. The inverse pitch depends linearly on chiral fraction and decreases with increasing temperature, indicating that achiral and chiral molecules participate in the assembly structure similarly. The helical twisting power is significantly larger than for other chiral lyotropic liquid crystals due to the very high scission energy of the investigated system.

Purpose: This study aimed to examine how compositions of 24-h time use and time reallocations between movement behaviors are associated with cardiometabolic health in a population-based sample of middle-age Finnish adults., Methods: Participants were 3443 adults 46 yr of age from the Northern Finland Birth Cohort 1966 study. Participants wore a hip-worn accelerometer for 14 d from which time spent in sedentary behavior (SB), light-intensity physical activity (LPA), and moderate- to vigorous-intensity physical activity (MVPA) were determined. These data were combined with self-reported sleep to obtain the 24-h time-use composition. Cardiometabolic outcomes included adiposity markers, blood lipid levels, and markers of glucose control and insulin sensitivity. Multivariable-adjusted regression analysis, using a compositional data analysis approach based on isometric log-ratio transformation, was used to examine associations between movement behaviors with cardiometabolic outcomes., Results: More daily time in MVPA and LPA, relative to other movement behaviors, was consistently favorably associated with all cardiometabolic outcomes. For example, relative to time spent in other behaviors, 30 min·d-1 more MVPA and LPA were both associated with lower 2-h post-glucose load insulin level (-11.8% and -2.7%, respectively). Relative to other movement behaviors, more daily time in SB was adversely associated with adiposity measures, lipid levels, and markers of insulin sensitivity, and more daily time asleep was adversely associated with adiposity measures, blood lipid, fasting plasma glucose, and 2-h insulin. For example, 60 min·d-1 more SB and sleep relative to the remaining behaviors were both associated with higher 2-h insulin (3.5% and 5.7%, respectively)., Conclusions: Altering daily movement behavior compositions to incorporate more MVPA at the expense of any other movement behavior, or more LPA at the expense of SB or sleep, could help to improve cardiometabolic health in midadulthood., (Copyright © 2020 by the American College of Sports Medicine.)

Recent measurements of the elastic constants in lyotropic chromonic liquid crystals (LCLCs) have revealed an anomalously small twist elastic constant compared to the splay and bend constants. Interestingly, measurements of the elastic constants in the micellar lyotropic liquid crystals (LLCs) that are formed by surfactants, by far the most ubiquitous and studied class of LLCs, are extremely rare and report only the ratios of elastic constants and do not include the twist elastic constant. By means of light scattering, this study presents absolute values of the elastic constants and their corresponding viscosities for the nematic phase of a standard LLC composed of disk-shaped micelles. Very different elastic moduli are found. While the splay elastic constant is in the typical range of 1.5 pN as is true in general for thermotropic nematics, the twist elastic constant is found to be one order of magnitude smaller (0.30 pN) and almost two orders of magnitude smaller than the bend elastic constant (21 pN). These results demonstrate that a small twist elastic constant is not restricted to the special case of LCLCs, but is true for LLCs in general. The reason for this extremely small twist elastic constant very likely originates with the flexibility of the assemblies that are the building blocks of both micellar and chromonic lyotropic liquid crystals., Competing Interests: The authors declare no competing interest.

Objective: Physical activity is advocated for a range of benefits to the uncomplicated pregnancy. We investigated associations of mid-pregnancy physical activity with maternal and neonatal health in white British and Pakistani-origin women from a deprived urban setting., Methods: The study was performed in 6921 pregnant women (53% Pakistani-origin) who contributed data for 7305 singleton births. At 26-28 weeks gestation, women were grouped into four activity levels (inactive/somewhat active/moderately active/active) based on their self-reported physical activity. Linear regression with robust standard errors was used to calculate adjusted mean differences in health markers between the four groups of physical activity (reference group: inactive)., Results: Three-quarters (74%) of Pakistani-origin women and 39% of white British women were inactive. Trend-tests revealed that more active white British women tended to be less adipose, had lower fasting and postload glucose levels, lower triglyceride concentrations, and their babies were less adipose (smaller triceps and subscapular skinfolds) than less active white British women. Somewhat active Pakistani-origin women exhibited lower triglyceride concentrations and systolic blood pressure, higher high-density lipoprotein cholesterol levels, and their babies were less adipose (smaller mid-upper arm and abdominal circumferences; lower cord-blood leptin concentration) compared to inactive Pakistani-origin women. No associations were observed for gestational age or birth weight., Conclusions: Physical activity performed mid-pregnancy was beneficially associated with maternal cardiometabolic health and neonatal adiposity, without influencing gestational age or birth weight. Associations were dose-dependent in white British women, and even a small amount of mid-pregnancy physical activity appeared to benefit some health markers in Pakistani-origin women.

Background: Physical activity performed while pregnant is beneficially associated with maternal cardiovascular health. It is unknown if benefits extend to neonatal cardiovascular health. This study investigated associations of maternal physical activity with neonatal cord blood lipid and lipoprotein concentrations., Methods: Cord blood lipids were measured at birth in a pseudorandomly selected subgroup of Born in Bradford birth cohort participants (N = 1634). Pregnant women were grouped into 4 activity categories (inactive/somewhat active/moderately active/active) based on their self-reported physical activity at 26- to 28-weeks gestation. Regression was used to calculate adjusted mean differences in neonatal cord blood lipid concentrations among the 4 groups of physical activity., Results: Maternal physical activity was associated with higher neonatal cord blood high-density lipoprotein cholesterol. Cord blood high-density lipoprotein cholesterol was higher in neonates of women who were somewhat and moderately active compared with neonates of women who were inactive. There were no associations of pregnancy physical activity with triglycerides, low-density lipoprotein, very low-density lipoprotein cholesterol, or adiponectin levels., Conclusions: Maternal physical activity is favorably associated with neonatal cord blood high-density lipoprotein cholesterol levels. This novel beneficial finding highlights the potential for physical activity in pregnancy to aid the early prevention of cardiovascular disease.

Background: Evidence suggests that South Asian school-aged children and adults are less active compared to the white British population. It is unknown if this generalises to young children. We aimed to describe variability in levels of physical activity and sedentary time in a bi-ethnic sample of young children from a deprived location., Methods: This observational study included 202 South Asian and 140 white British children aged 1.5 to 5y, who provided 3181 valid days of triaxial accelerometry (Actigraph GT3X+). Variability in sedentary time and physical activity levels were analysed by linear multilevel modelling. Logistic multilevel regression was used to identify factors associated with physical inactivity (failing to perform ≥180 min of total physical activity including ≥60 min moderate-to-vigorous physical activity (MVPA) per day)., Results: There were no significant ethnic differences in the overall levels of behaviours; South Asian and white British children spent half of daily time sedentary, just over 40% in light physical activity, and the remaining 7.5 to 8% of time in MVPA. Sedentary time was lower and physical activity levels were higher in older children, and levels of MVPA and vector magnitude counts per minute (CPM) were higher on weekends compared to weekdays. In South Asian children, sedentary time was lower on weekends. Sedentary time was lower and physical activity levels were higher in spring compared to winter in white British children, and in all seasons compared to winter in South Asian children. South Asian children born at high birth weight performed more MVPA, and in both ethnicities there was some evidence that children with older mothers were more sedentary and less active. Sedentary time was higher and light physical activity was lower in South Asian children in the highest compared to the lowest income families. South Asian girls performed less MVPA, registered fewer vector magnitude CPM, and were 3.5 times more likely to be physically inactive than South Asian boys., Conclusions: Sedentary time and physical activity levels vary by socio-demographic, temporal and perinatal characteristics in young children from a deprived location. South Asian girls have the most to gain from efforts to increase physical activity levels., Trial Registration: The Pre-schoolers in the Playground (PiP) pilot randomized controlled trial is registered with the ISRCTN (ISRCTN54165860; http://www.isrctn.com).

Objective: To examine the relationship between physical activity, sedentary behaviors, and social isolation in a representative sample of Brazilian adolescents., Method: Cross sectional analyses using data from the Brazilian Scholar Health Survey conducted in 2015. The sample included 100,839 adolescents (mean age: 14.3 y, 51.4% Female) from 3040 schools. Information about social isolation (number of close friends and perceived loneliness), physical activity (International Physical Activity Questionnaire) and sedentary behaviors (total sitting time and TV viewing) were self-reported. Chronological age, race and type of city (state capital or other) were co-variables. Logistic regression models were used to analyze the data (results are presented as odds ratios (OR) with 95% confidence intervals)., Results: Physical activity was associated with lower odds of both social isolation indicators in boys, and with lower likelihood of having few friends in girls. Greater sitting time was associated with higher likelihood of social isolation, as was low (<1 h/d) [boys: OR: 1.54 (95% CI: 1.33 to 1.77); girls: OR: 1.31 (95% CI: 1.17 to 1.48] and high TV viewing (≥8 h/d) [boys: OR: 1.75 (95% CI: 1.47 to 2.09)]; girls: OR: 1.58 (95% CI: 1.37 to 1.82)]. More than 300 min/week of physical activity was sufficient to eliminate the association of high TV viewing and high sitting time with markers of social isolation in boys., Conclusion: Physical activity is associated with a lower prevalence of social isolation, especially among boys. Both high and low amounts of TV viewing increase the likelihood of social isolation. Physical activity reduced the association between TV viewing and sitting with social isolation among boys., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Our aim was to identify prenatal, biological and environmental correlates of child to adolescence physical activity maintenance in 1,186 Brazilian youth (525 boys) aged between 10 and 16 years. Current and former physical activity levels were obtained cross-sectionally through questionnaires. As potential correlates, parent's activity levels, socioeconomic status and offspring's birth weight were self-reported by parents. Somatic maturation was estimated by the peak of height velocity. Logistic regression analyses revealed that, regardless of chronological age, males were more likely to be active in childhood (OR = 1.73 [CI 95% = 1.33 to 2.27]) and to maintain physical activity (adjusted by chronological age, sex, birth weight and mother's physical activity) (OR = 3.58 [CI 95% = 2.32 to 5.54]), as well as late maturing adolescents (OR = 2.52 [CI 95% = 1.02 to 6.22]). Adolescents whose mother was inactive (OR = 0.31 [CI 95% = 0.11 to 0.86]) also had a lower probability of maintaining physical activity. Thus, girls, adolescents born with low weight and those with inactive mother are less likely to maintain physical activity levels from childhood to adolescence.

One of the most simple cases in which chirality at the microscopic level produces a chiral macroscopic structure is the chiral nematic liquid crystal phase. In such a phase, the preferred direction of molecular orientation rotates in helical fashion, with the pitch of the helix in different systems ranging from around 100 nm to as large as can be measured (∼10 mm). For almost all thermotropic and lyotropic liquid crystals, the ordered entities are formed from strong bonds, so the pitch varies in accordance with how the interactions between these largely immutable entities are affected by changing conditions. A unique exception are lyotropic chromonic liquid crystals (LCLCs) that spontaneously form weakly bound assemblies in solution, the size of which depends strongly on experimental parameters. While the temperature dependence of the pitch has been measured for chiral LCLCs formed by short strands of DNA (DNA-LCLCs), such is not the case for chiral LCLCs formed by small molecules. Polarized optical microscopy experiments on small molecule chiral LCLCs reveal the changing assembly size through a temperature dependence of the pitch not typical for many other systems, including the most recent measurements on DNA-LCLCs. In fact, the pitch measurements in small molecule chiral LCLCs strongly increase in value as the temperature is increased and the assemblies shrink in size. Theoretical considerations provide some help in understanding this phenomena, but leave much to be explained.

Objective: To test the biocultural model through direct and indirect associations between biological maturation, adiposity, cardiorespiratory fitness, feelings of sadness, social relationships, and physical activity in adolescents., Methods: This was a cross-sectional study conducted with 1,152 Brazilian adolescents aged between 10 and 17 years. Somatic maturation was estimated through Mirwald's method (peak height velocity). Physical activity was assessed through Baecke questionnaire (occupational, leisure, and sport contexts). Body mass index, body fat (sum of skinfolds), cardiorespiratory fitness (20-m shuttle run test), self-perceptions of social relationship, and frequency of sadness feelings were obtained for statistical modeling., Results: Somatic maturation is directly related to sport practice and leisure time physical activity only among girls (β=0.12, p<0.05 and β=0.09, respectively, p<0.05). Moreover, biological (adiposity and cardiorespiratory fitness), psychological (sadness), and social (satisfaction with social relationships) variables mediated the association between maturity and physical activity in boys and for occupational physical activity in girls. In general, models presented good fit coefficients., Conclusion: Biocultural model presents good fit and emotional/biological factors mediate part of the relationship between somatic maturation and physical activity., (Copyright © 2017 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.)

We study Brownian dynamics of colloidal spheres, with planar anchoring conditions, suspended in the nematic phase of the lyotropic chromonic liquid crystal disodium chromoglycate (DSCG). Unlike typical liquid crystals, the unusually small twist elastic modulus of DSCG permits two energetically distinct helical distortions (twisted tails) of the nematic director to "dress" the suspended spheres. Video microscopy is used to characterize the helical distortions versus particle size and to measure particle mean-square displacements. Diffusion coefficients parallel and perpendicular to the far-field director, and their anisotropy ratio, are different for the two twisted tail configurations. Moreover, the crossover from subdiffusive to diffusive behavior is anomalously slow for motion perpendicular to the director (>100  s). Simple arguments using Miesowicz viscosities and ideas about twist relaxation are suggested to understand the mean-square displacement observations.

Objective: This study aimed to examine the associations of TV parameters with adiposity in early life., Methods: Data were collected as part of the Born in Bradford (BiB) longitudinal birth cohort study. Child TV viewing duration was parent reported, and BMI, the sum of triceps and subscapular skinfolds, and waist circumference were measured at ~12, 18, 24, and 36 months of age in 1,338 children. Mixed effects models were used to quantify adjusted associations of TV viewing duration with adiposity markers, incorporating data from all time points. Linear regression was used to investigate differences in adiposity levels across frequencies of eating meals and snacks while watching TV at age ~24 months and between children who did and did not have a TV in their bedroom at age ~36 months., Results: Every 1 h/d of TV viewing was associated with a 0.075-cm larger (95% CI: 0.0034-0.15) waist circumference, independent of covariates including sleep duration, dietary factors, and physical activity level. There was no evidence for any other associations., Conclusions: TV viewing duration is independently associated with abdominal adiposity in young children. Limiting TV viewing from an early age may be important for primary prevention of obesity., (© 2018 The Obesity Society.)

There is a dearth of suitable metrics capable of objectively quantifying motor competence. Further, objective movement quality characteristics during free play have not been investigated in pre-school children. The aims of this study were to characterize children's free play physical activity and investigate how gait quality characteristics cluster with free play in pre-school children (3-5 years old). Sixty-one children (39 boys; 4.3 ± 0.7 years, 1.04 ± 0.05 m, 17.8 ± 3.2 kg) completed the movement assessment battery for children and took part in free play while wearing an ankle- and hip-mounted accelerometer. Characteristics of movement quality were profiled using a clustering algorithm. Spearman's rho and the Mann-Whitney U tests were used to assess relationships between movement quality characteristics and motor competence classification differences in integrated acceleration and spectral purity, respectively. Significant differences were found between motor competency classifications for spectral purity and integrated acceleration (p < .001). Spectral purity was hierarchically clustered with motor competence and integrated acceleration. Significant positive correlations were found between spectral purity, integrated acceleration and motor competence (p < .001). This is the first study to report spectral purity in pre-school children and the results suggest that the underlying frequency component of movement is clustered with motor competence.

Aim: Examine the association between child and adolescent physical activity maintenance categories and metabolic profile in adolescence., Methods: This cross-sectional study was conducted with 1152 adolescents (57.4% female) aged 10-16 years from Londrina, Brazil. Physical activity was self-reported in childhood (7-10 years old, retrospective data) and adolescence through questionnaires. Cardiorespiratory fitness (20 m shuttle-run test), body fat (skinfolds), waist circumference, blood pressure (automatic instrument) and blood variables (fasting glucose, HDL-cholesterol and triglycerides) were measured at adolescence., Results: Frequency of physical activity in childhood and adolescence was 50.3 and 17.2%, respectively, and only 25.7% of boys and 10.9% of girls were active at both ages. Adolescents who were physically active in childhood alone were less likely [OR = 0.71 (95% CI: 0.52-0.97)] to present low cardiorespiratory fitness in adolescence compared to those who were non-active in childhood. Regardless of controlled, actives in childhood and adolescence were less likely to present low cardiorespiratory fitness [OR = 0.50 (95% CI: 0.34-0.73)], high blood pressure [OR = 0.52 (95% CI: 0.32-0.85)] and high metabolic risk score [OR = 0.44 (95% CI: 0.22-0.90)] compared to the non-actives at both ages., Conclusions: Actives through childhood to adolescence are less likely to present low cardiorespiratory fitness, high blood pressure and high metabolic risk.

Objectives: We investigated the impact of a standing desk intervention on daily objectively monitored sedentary behavior and physical activity in 6th grade school students., Design: Cluster non-randomised controlled trial., Method: Two classes (intervention students: n=22 [aged 11.8±0.4years]; control students: n=27 [11.6±0.5years]) from a public school in Lisbon were selected. The intervention involved replacing traditional seated classroom desks for standing desks, for a total duration of 16 weeks, in addition to performing teacher training and holding education/motivation sessions with students and parents. Sedentary behavior (ActivPAL inclinometer) and physical activity (Actigraph GT3X+ accelerometer) were measured for seven days immediately before and after the intervention., Results: There were no differences in baseline behaviors between intervention and control groups (p>0.05). At follow-up (16 weeks), it was observed that the intervention group had decreased time spent sitting (total week: -6.8% and at school: -13.0% relative to baseline) and increased standing (total week: 16.5% and at school: 31.0%) based on inclinometer values (p-value for interaction group*time <0.05). No significant differences in activity outcomes were observed outside school time (week or weekend) between groups., Conclusion: We conclude that a 16 week classroom standing desk intervention successfully reduced sitting time and increase standing time at school, with no observed compensatory effects outside of school time., (Copyright © 2018 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.)

Background: This study describes the levels and patterns of television (TV) viewing in Brazilian adults and investigates associations of TV viewing with hypertension, type 2 diabetes, and heart disease., Methods: Data from the Brazilian Health Survey, a nationally representative survey that was conducted in 2013 (N = 60,202 men and women aged ≥18 y), were used. Information regarding TV viewing, physician diagnoses of type 2 diabetes, hypertension, and heart disease was collected via interview-administered questionnaire. Data on covariables (including chronological age, educational status, skin color, sodium consumption, sugar consumption, tobacco smoking, alcohol consumption, and leisure-time physical activity) were also self-reported. Logistic regression models and population attributable fractions were used for the etiological analyses., Results: The prevalence (95% confidence interval) of >4 hours per day of TV viewing was 12.7% (12.0-13.4) in men and 17.5% (16.8-18.3) in women. Men and women being younger or older, moderately educated, living alone, smoking tobacco, and drinking alcohol were associated with higher reported TV viewing time. Odds ratios (95% confidence interval) revealed that >4 hours per day of TV viewing was associated with type 2 diabetes [male: 1.64 (1.23-2.17) and female: 1.33 (1.09-1.63)], hypertension [male: 1.36 (1.14-1.63) and female: 1.20 (1.05-1.37)], and heart disease [male: 1.96 (1.43-2.69) and female: 1.30 (1.00-1.68)]. Exceeding 4 hours per day of TV viewing was responsible for 6.8% of type 2 diabetes, 3.7% of hypertension, and 7.5% of heart disease cases., Conclusions: Independent of covariates, >4 hours per day of TV viewing was associated with type 2 diabetes, hypertension, and heart disease. High volumes of TV viewing are prevalent and appear to contribute to chronic disease burden.

Introduction: Cardiovascular disease risk markers have become more prevalent in childhood. To provide increased understanding of the etiology of this public health issue, we investigated associations between family characteristics with cardiovascular disease risk markers in adolescents from a developing nation., Methods: In this cross-sectional study data for fasting glucose, lipoproteins (LDL-C and HDL-C), triglycerides, and total cholesterol were collected from 991 adolescents aged 10-17 who were recruited from public schools in Londrina city, Southern Brazil. Family history of cardiovascular disease and parental engagement in risk behavior (alcohol consumption and tobacco smoking) were collected using a self-reported parental questionnaire. Socioeconomic status, adolescent physical activity (estimated by Baecke questionnaire), self-reported tobacco and alcohol intake, and somatic maturation (age at peak height velocity) were used as covariates. Logistic regression was used for the main analyses., Results: Independent of adolescent lifestyle behaviors, associations (OR adj [95% CI]) were found between: (1) paternal family history of cardiovascular disease with increased likelihood of high adolescent offspring BMI (1.53 [1.01 to 2.32]) and high triglycerides (2.93 [1.04 to 8.27]); (2) maternal family history of cardiovascular disease with heightened odds of high adolescent offspring triglycerides (2.84 [1.02 to 7.91]); (3) maternal cardiovascular disease with higher odds of high fasting glucose (2.16 [1.13 to 4.14]), and (4) maternal smoking with increased odds of high LDL-C (1.78 [1.14 to 2.79]) and high total cholesterol (1.77 [1.01 to 3.10]) in adolescent offspring., Conclusion: Family history of cardiovascular disease and maternal tobacco smoking are related to increased cardiovascular risk in adolescents, potentially independent of their own lifestyle behaviors., (© 2017 Wiley Periodicals, Inc.)

This study was aimed to investigate associations between birth weight and multiple adiposity indicators in youth, and to examine potential mediating effects by biological maturation. This was a school-based study involving 981 Brazilian adolescents aged between 10 and 17 years. Birth weight was reported retrospectively by mothers. Maturation was estimated by age of peak height velocity. Adiposity indicators included body mass index (BMI), waist circumference and percent body fat estimated from triceps and subscapular skinfolds. Multilevel mediation analyses were performed using the Sobel test, adjusted for chronological age, gestational age, cardiorespiratory fitness and socio-economic status. Except for body fat in girls, biological maturation partly or fully mediated (P<0.05) positive relationships between birth weight with all other obesity indicators in both sexes with their respective values of indirect effects with 95% confidence intervals: BMI [boys: 0.44 (0.06-0.82); girls: 0.38 (0.13-0.64)], waist circumference [boys: 1.14 (0.22-2.05); girls: 0.87 (0.26-1.48)] and body fat [boys: 0.60 (0.13-1.07)]. To conclude, birth weight is associated with elevated obesity risk in adolescence and biological maturation seems to at least partly mediate this relationship.

Background: Excessive screen viewing in early childhood is associated with poor physical and psycho-social health and poor cognitive development. This study aimed to understand the prevalence, trajectory and determinants of television viewing time in early childhood to inform intervention development., Methods: In this prospective longitudinal study, mothers of 1558 children (589 white British, 757 Pakistani heritage, 212 other ethnicities) completed questionnaires when their children were approximately 6, 12, 18, 24 and 36 months old. Mothers answered questions about their own and their child's TV-time. TV-time trajectories were estimated by linear longitudinal multilevel modeling, potential determinants were considered in models., Results: The modelled trajectory estimated that 75% of children aged 12 months exceeded guidelines of zero screen-time. At 12 months of age an accelerated increase in TV-time was observed (<1 h/day at 14 months, >2 h/day by 30 months old). For every hour of mothers' TV-time and every hour the TV was on in the home, children's TV-time was 8 min and 1 min higher respectively at 6 months old (P < 0.05), and 15 min and 3 min higher respectively at 36 months old (P < 0.05). Children whose mothers did not agree that it was important their child did not watch too much TV, had 17 min more TV-time than their counterparts (P < 0.05). Children of first time mothers had 6 min more TV-time (P < 0.05). At 12 months of age, children of mothers experiencing stress watched 8 min more TV (P < 0.05). By 36 months, children of Pakistani heritage mothers had 22 min more TV-time than those of white British mothers (P < 0.05), and an additional 35 min of TV-time if their mother was not born in the UK (P < 0.05)., Conclusions: High levels of TV-time were prevalent. Intervention developers should consider targeting interventions before 12 months of age. Modifiable determinants included mothers' own TV-time, the time the television is on in the home and mothers' attitude towards child TV-time. These behaviours may be key components to address in interventions for parents. Mothers experiencing stress, first time mothers, and Pakistani heritage mothers (particularly those born outside of the UK), may be priority groups for intervention.

Drop drying and deposition phenomena reveal a rich interplay of fundamental science and engineering, give rise to fascinating everyday effects (coffee rings), and influence technologies ranging from printing to genotyping. Here we investigate evaporation dynamics, morphology, and deposition patterns of drying lyotropic chromonic liquid crystal droplets. These drops differ from typical evaporating colloidal drops primarily due to their concentration-dependent isotropic, nematic, and columnar phases. Phase separation occurs during evaporation, and in the process creates surface tension gradients and significant density and viscosity variation within the droplet. As a result, the drying multiphase drops exhibit different convective currents, drop morphologies, and deposition patterns (coffee-rings).

Purpose: This study aimed to investigate associations of objectively measured physical activity (PA) and sedentary time with adiposity in a predominantly biethnic (South Asian and White British) sample of young children., Methods: The sample included 333 children age 11 months to 5 yr who provided 526 cross-sectional observations for PA and body composition. Total PA volume (vector magnitude counts per minute), daily time at multiple intensity levels (the cumulative time in activity >500, >1000, >1500, …, >6000 counts per minute), and time spent sedentary (<820 counts per minute), in light PA (820-3907 counts per minute) and in moderate-to-vigorous PA (≥3908 counts per minute) were estimated with triaxial accelerometry. Indicators of adiposity included body mass index, waist circumference, and the sum of subscapular and triceps skinfold thicknesses. Statistical analyses were performed using multilevel regression and isotemporal substitution models adjusted for confounders. Effect modification by ethnicity was examined., Results: There was no evidence for effect modification by ethnicity (P interaction ≥ 0.13). In the whole sample, the accumulated time spent above 3500 counts per minute (i.e., high light-intensity PA) was inversely associated with the sum of skinfolds (β = -0.60 mm, 95% confidence interval [CI] = -1.19 to -0.021, per 20 min·d), and the magnitude of association increased dose dependently with PA intensity (peaking for time spent >6000 counts per minute = -1.57 mm, 95% CI = -3.01 to -0.12, per 20 min·d). The substitution of 20 min·d of sedentary time with moderate-to-vigorous PA was associated with a lower sum of skinfolds (-0.77 mm, 95% CI = -1.46 to -0.084)., Conclusions: High light-intensity PA appears to be beneficial for body composition in young South Asian and White British children, but higher-intensity PA is more advantageous.

Background: Both cardiorespiratory fitness and body fat have been independently related to metabolic syndrome in adolescents; however, the strength of these relationships seems to be dependent on the outcome composition., Aim: To analyse the relationship between cardiorespiratory fitness and body fat combined with different indicators of metabolic risk in adolescents., Subjects and Methods: The sample was composed of 957 adolescents (58.7% girls). Cardiorespiratory fitness was obtained using the 20-metre shuttle run test and skinfold thickness was collected for body fat estimation. Metabolic risk score was calculated from waist circumference, systolic and diastolic blood pressure, glucose, HDL cholesterol and triglycerides measurements and an alternative outcome without the central obesity indicator was adopted. Chronological age and somatic maturity were used as covariates., Results: Higher metabolic risk was observed in the highest fat/lowest fit adolescents (p < .05), regardless of sex and outcome. In the regression models, for full metabolic risk score, body fat presented higher coefficients compared to cardiorespiratory fitness in both sexes (boys: 0.501 vs -0.097; girls: 0.485 vs -0.087); however, in the metabolic risk without waist circumference, the coefficients became closer (boys: 0.290 vs -0.146; girls: 0.265 vs -0.120), with a concomitant decrease in body fat and increase in cardiorespiratory fitness coefficients., Conclusion: These findings suggest that body fat is strongly related to cardiovascular risk, but, when the outcome is calculated without the central obesity indicator, cardiorespiratory fitness becomes more related to metabolic risk.

Background: The minimum intensity of physical activity (PA) that is associated with favourable body composition and cardiorespiratory fitness (CRF) remains unknown., Objective: To investigate cross-sectional associations of PA and sedentary time (ST) with body composition and CRF in mid-childhood., Methods: PA, ST, body composition and CRF were measured in a population-based sample of 410 children (aged 7.6 ± 0.4 years). Combined heart-rate and movement sensing provided estimates of PA energy expenditure (PAEE, kJ/kg/day) and time (min/day) at multiple fine-grained metabolic equivalent (MET) levels, which were also collapsed to ST and light PA (LPA), moderate PA (MPA) and vigorous PA (VPA). Fat mass index (FMI, kg/m 2 ), trunk fat mass index (TFMI, kg/m 2 ) and fat-free mass index (FFMI, kg/m 2.5 ) were derived from dual-energy X-ray absorptiometry. Maximal workload from a cycle ergometer test provided a measure of CRF (W/kg FFM). Linear regression and isotemporal substitution models were used to investigate associations., Results: The cumulative time above 2 METs (221 J/min/kg) was inversely associated with FMI and TFMI in both sexes (p < 0.001) whereas time spent above 3 METs was positively associated with CRF (p ≤ 0.002); CRF increased and adiposity decreased dose-dependently with increasing MET levels. ST was positively associated with FMI and TFMI (p < 0.001) but there were inverse associations between all PA categories (including LPA) and adiposity (p ≤ 0.002); the magnitude of these associations depended on the activity being displaced in isotemporal substitution models but were consistently stronger for VPA. PAEE, MPA and to a greater extent VPA, were all positively related to CRF (p ≤ 0.001)., Conclusions: PA exceeding 2 METs is associated with lower adiposity in mid-childhood, whereas PA of 3 METs is required to benefit CRF. VPA was most beneficial for fitness and fatness, from a time-for-time perspective, but displacing any lower-for-higher intensity may be an important first-order public health strategy. Clinical trial registry number (website): NCT01803776 ( https://clinicaltrials.gov/ct2/show/NCT01803776 ).

Study Objectives: To examine independent associations of sleep duration with total and abdominal adiposity, and the bidirectionality of these associations, in a young biethnic sample of children from a disadvantaged location., Methods: Child sleep duration (h/day) was parent-reported by questionnaire and indices of total (body weight, body mass index, percent body fat (%BF), sum of skinfolds) and abdominal adiposity (waist circumference) were measured using standard anthropometric procedures at approximately 12, 18, 24, and 36 months of age in 1,338 children (58% South Asian; 42% White). Mixed effects models were used to quantify independent associations (expressed as standardised β-coefficients (95% confidence interval (CI)) of sleep duration with adiposity indices using data from all four time-points. Factors considered for adjustment in models included basic demographics, pregnancy and birth characteristics, and lifestyle behaviours., Results: With the exception of the sum of skinfolds, sleep duration was inversely and independently associated with indices of total and abdominal adiposity in South Asian children. For example, one standard deviation (SD) higher sleep duration was associated with reduced %BF by -0.029 (95% CI: -0.053, -0.0043) SDs. Higher adiposity was also independently associated with shorter sleep duration in South Asian children (for example, %BF: β = -0.10 (-0.16, -0.028) SDs). There were no significant associations in White children., Conclusions: Associations between sleep duration and adiposity are bidirectional and independent among South Asian children from a disadvantaged location. The results highlight the importance of considering adiposity as both a determinant of decreased sleep and a potential consequence., (© Sleep Research Society 2016. Published by Oxford University Press [on behalf of the Sleep Research Society].)

Background: Earlier biological maturation has been related to increased metabolic risk. In this study, we verified mediating effects by central adiposity of the relationship between somatic maturity and metabolic risk factors in adolescents., Methods: In a cross-sectional study, 1034 adolescents aged 10-16 years from Londrina/PR/Brazil were evaluated. The age of peak height velocity (PHV) method was used to evaluate somatic maturity. Central adiposity was estimated through waist circumference measurements. Fasting glucose, triglycerides, high-density lipoprotein cholesterol (HDL-C), and blood pressure were measured as metabolic risk indicators. Physical activity (Baecke questionnaire) and cardiorespiratory fitness (20-m shuttle run test) were used as covariates., Results: Except for fasting glucose, waist circumference showed partial or full mediation of the relationship between maturity and the following metabolic risk factors with their respective z-score values: triglycerides (boys = -3.554 vs. girls = -5.031), HDL-C (boys = +5.300 vs. girls = +5.905), systolic blood pressure (boys = -3.540 vs. girls = -3.763), diastolic blood pressure (boys = -2.967 vs. girls = -3.264), and metabolic risk score (boys = -5.339 vs. girls = -6.362)., Conclusions: The results suggest that central obesity plays a mediating role in the relationship between somatic maturation and metabolic risk during adolescence.

Measuring physical activity (PA) and sedentary time (ST) in young children (<5 years) is complex. Objective measures have high validity but require specialist expertise, are expensive, and can be burdensome for participants. A proxy-report instrument for young children that accurately measures PA and ST is needed. The aim of this study was to assess the reliability and validity of the Early Years Physical Activity Questionnaire (EY-PAQ). In a setting where English and Urdu are the predominant languages spoken by parents of young children, a sample of 196 parents and their young children (mean age 3.2 ± 0.8 years) from Bradford, UK took part in the study. A total of 156 (79.6%) questionnaires were completed in English and 40 (20.4%) were completed in transliterated Urdu. A total of 109 parents took part in the reliability aspect of the study, which involved completion of the EY-PAQ on two occasions (7.2 days apart; standard deviation (SD) = 1.1). All 196 participants took part in the validity aspect which involved comparison of EY-PAQ scores against accelerometry. Validty anaylsis used all data and data falling with specific MVPA and ST boundaries. Reliability was assessed using intra-class correlations (ICC) and validity by Bland⁻Altman plots and rank correlation coefficients. The test re-test reliability of the EY-PAQ was moderate for ST (ICC = 0.47) and fair for moderate-to-vigorous physical activity (MVPA)(ICC = 0.35). The EY-PAQ had poor agreement with accelerometer-determined ST (mean difference = -87.5 min·day -1 ) and good agreement for MVPA (mean difference = 7.1 min·day -1 ) limits of agreement were wide for all variables. The rank correlation coefficient was non-significant for ST (rho = 0.19) and significant for MVPA (rho = 0.30). The EY-PAQ has comparable validity and reliability to other PA self-report tools and is a promising population-based measure of young children's habitual MVPA but not ST. In situations when objective methods are not possible for measurement of young children's MVPA, the EY-PAQ may be a suitable alternative but only if boundaries are applied.