5,132 research outputs found

    New observations on Saturnella saturnus (Steinecke) Fott: the first British record of a little-known enigmatic ‘green’ alga

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    Saturnella saturnus was discovered in March 2014 in open-water pools on blanket peatland at the Moor House - Upper Teesdale National Nature Reserve, straddling Cumbria and County Durham in NE England. This is the first record for the British Isles of a little-known alga known previously only from a few peat bog areas, mainly in mainland Europe. The literature is reviewed and new observations presented on its morphology and reproduction based on LM examination of living cells. New observations on the chloroplast structure and cytoplasmic inclusions (especially oil droplets) are discussed in relation to the findings of earlier studies. Doubt attaches as whether it is a chlorophyte or a xanthophyte and the identity of small spherical inclusions that have been frequently interpreted as autospores. It occurs in Upper Teesdale in pools that are that are small, relatively newly formed and mostly well-oxygenated. Also discussed is its relationship to Trochiscia, another coloniser of peatland pools. Photographic images are presented for the first time and comments made on its ecology in the context of blanket bog conservation projects and apparent rarity

    The effect of laser power, traverse velocity and spot size on the peel resistance of a polypropylene/adhesive bond

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    Abstract The mean peel resistance force achieved with respect to variation in the laser power, incident spot traverse velocity and incident spot diameter between linear low density polyethylene film backed by a thin commercial adhesive coating that were bonded to a polypropylene substrate via thermal activation provided by a 27W CO 2 laser is discussed in this work. The results gathered for this work have been used to generate a novel empirical tool that predicts the CO 2 laser power required to achieve a viable adhesive bond for this material combination. This predictive tool will enable the packaging industry to achieve markedly increased financial yield, process efficiency, reduced material waste and process flexibility. A laser spot size dependent linear increase in laser line energy was necessary for this material combination, suggesting the minimal impact of thermal strain rate. Moreover a high level of repeatability around this threshold laser line energy was indicated, suggesting that laser activated adhesive bonding of such polymer films is viable. The adhesion between the material combination trialled here responded linearly to thermal load. In particular, when using the smallest diameter laser spot, it is proposed that the resulting high irradiance caused film or adhesive material damage; thus, resulting in reduced peel resistance force. The experimental work conducted indicated that the processing window of an incident CO 2 laser spot increases with respect to spot diameter, simultaneously yielding greater bond stability in the face of short-term laser variance

    The school policy, social, and physical environment and change in adolescent physical activity: An exploratory analysis using the LASSO.

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    PURPOSE: We examined the association between the school policy, social and physical environment and change in adolescent physical activity (PA) and explored how sex and socioeconomic status modified potential associations. METHODS: Data from the GoActive study were used for these analyses. Participants were adolescents (n = 1765, mean age±SD 13.2±0.4y) from the East of England, UK. Change in longitudinal accelerometer assessed moderate-to-vigorous physical activity (MVPA) was the outcome. School policy, social and physical environment features (n = 267) were exposures. The least absolute shrinkage and selection operator variable selection method (LASSO) was used to determine exposures most relevant to the outcome. Exposures selected by the LASSO were added to a multiple linear regression model with estimates of change in min/day of MVPA per 1-unit change in each exposure reported. Post-hoc analyses, exploring associations between change in variables selected by the LASSO and change in MVPA, were undertaken to further explain findings. FINDINGS: No school policy or physical environment features were selected by the LASSO as predictors of change in MVPA. The LASSO selected two school social environment variables (participants asking a friend to do physical activity; friend asking a participant to do physical activity) as potential predictors of change in MVPA but no significant associations were found in subsequent linear regression models for all participants (β [95%CI] -1.01 [-2.73;0.71] and 0.65 [-2.17;0.87] min/day respectively). In the post-hoc analyses, for every unit increase in change in participants asking a friend to do PA and change in a friend asking participants to do PA, an increase in MVPA of 2.78 (1.55;4.02) and 1.80 (0.48;3.11) min/day was predicted respectively. CONCLUSIONS: The school social environment is associated with PA during adolescence. Further exploration of how friendships during adolescence may be leveraged to support effective PA promotion in schools is warranted

    New missense variants in RELT causing hypomineralised amelogenesis imperfecta

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    Amelogenesis imperfecta (AI) is a heterogeneous group of genetic diseases characterised by dental enamel malformation. Pathogenic variants in at least 33 genes cause syndromic or non‐syndromic AI. Recently variants in RELT, encoding an orphan receptor in the tumour necrosis factor (TNF) superfamily, were found to cause recessive AI, as part of a syndrome encompassing small stature and severe childhood infections. Here we describe four additional families with autosomal recessive hypomineralised AI due to previously unreported homozygous mutations in RELT. Three families carried a homozygous missense variant in the fourth exon (c.164C > T, p.[T55I]) and a fourth family carried a homozygous missense variant in the 11th exon (c.1264C > T, p.[R422W]). We found no evidence of additional syndromic symptoms in affected individuals. Analyses of tooth microstructure with computerized tomography and scanning electron microscopy suggest a role for RELT in ameloblasts' coordination and interaction with the enamel matrix. Microsatellite genotyping in families segregating the T55I variant reveals a shared founder haplotype. These findings extend the RELT pathogenic variant spectrum, reveal a founder mutation in the UK Pakistani population and provide detailed analysis of human teeth affected by this hypomineralised phenotype, but do not support a possible syndromic presentation in all those with RELT‐variant associated AI

    Understanding Bank-Run Contagion

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    We study experimental coordination games to examine through which transmission channels and under which information conditions a panic-based depositor run at one bank may trigger a panic-based depositor run at another bank. We find that withdrawals at one bank trigger withdrawals at another bank by increasing players' beliefs that other depositors in their own bank will withdraw, making them more likely to withdraw as well. Observed withdrawals only affect depositors' beliefs, and are thus contagious when they form an informative signal about bank fundamentals

    Semiparametric Multivariate Accelerated Failure Time Model with Generalized Estimating Equations

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    The semiparametric accelerated failure time model is not as widely used as the Cox relative risk model mainly due to computational difficulties. Recent developments in least squares estimation and induced smoothing estimating equations provide promising tools to make the accelerate failure time models more attractive in practice. For semiparametric multivariate accelerated failure time models, we propose a generalized estimating equation approach to account for the multivariate dependence through working correlation structures. The marginal error distributions can be either identical as in sequential event settings or different as in parallel event settings. Some regression coefficients can be shared across margins as needed. The initial estimator is a rank-based estimator with Gehan's weight, but obtained from an induced smoothing approach with computation ease. The resulting estimator is consistent and asymptotically normal, with a variance estimated through a multiplier resampling method. In a simulation study, our estimator was up to three times as efficient as the initial estimator, especially with stronger multivariate dependence and heavier censoring percentage. Two real examples demonstrate the utility of the proposed method

    A cluster randomised controlled trial to evaluate the effectiveness and cost-effectiveness of the GoActive intervention to increase physical activity among adolescents aged 13-14 years.

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    INTRODUCTION: Adolescent physical activity promotion is rarely effective, despite adolescence being critical for preventing physical activity decline. Low adolescent physical activity is likely to last into adulthood, increasing health risks. The Get Others Active (GoActive) intervention is evidence-based and was developed iteratively with adolescents and teachers. This intervention aims to increase physical activity through increased peer support, self-efficacy, group cohesion, self-esteem and friendship quality, and is implemented using a tiered-leadership system. We previously established feasibility in one school and conducted a pilot randomised controlled trial (RCT) in three schools. METHODS AND ANALYSIS: We will conduct a school-based cluster RCT (CRCT) in 16 secondary schools targeting all year 9 students (n=2400). In eight schools, GoActive will run for two terms: weekly facilitation support from a council-funded intervention facilitator will be offered in term 1, with more distant support in term 2. Tutor groups choose two weekly activities, encouraged by older adolescent mentors and weekly peer leaders. Students gain points for trying new activities; points are entered into a between-class competition. Outcomes will be assessed at baseline, interim (week 6), postintervention (week 14-16) and 10-month follow-up (main outcome). The primary outcome will be change from baseline in daily accelerometer-assessed moderate-to-vigorous physical activity. Secondary outcomes include accelerometer-assessed activity intensities on weekdays/weekends; self-reported physical activity and psychosocial outcomes; cost-effectiveness and cost-utility analyses; mixed-methods process evaluation integrating information from focus groups and participation logs/questionnaires. ETHICS AND DISSEMINATION: Ethical approval for the conduct of the study was gained from the University of Cambridge Psychology Research Ethics Committee. Given the lack of rigorously evaluated interventions, and the inclusion of objective measurement of physical activity, long-term follow-up and testing of causal pathways, the results of a CRCT of the effectiveness and cost-effectiveness of GoActive are expected to add substantially to the limited evidence on adolescent physical activity promotion. Workshops will be held with key stakeholders including students, parents, teachers, school governors and government representatives to discuss plans for wider dissemination of the intervention. TRIAL REGISTRATION NUMBER: ISRCTN31583496
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