Special Article: Physical Activity, Physical Fitness, and Cardiovascular Risk Factors in Childhood

In adults, physical activity and exercise training are associated with reduced cardiovascular morbidity and mortality, a reduced likelihood of developing adverse cardiovascular risk factors, and improved insulin sensitivity. In childhood, participation in appropriate physical activity may prevent the development of cardiovascular risk factors in the future and complement treatment of existing cardiovascular risk factors, including hypertension, dyslipidemia, and overweight. Exercise in children can also significantly improve insulin sensitivity independent of weight loss. These e fects are mediated in overweight children by increases in lean body mass relative to fat mass and associated improvements in inflammatory mediators, endothelial function, and the associated adverse hormonal milieu

Experimental investigation of local-flexural interactive buckling of cold-formed steel channel columns

This paper presents the results of a comprehensive experimental programme aimed at studying the interaction of local and overall flexural buckling in cold-formed steel (CFS) plain and lipped channels under axial compression. The results were further used to verify the accuracy of the current design procedures in Eurocode 3, as well as to evaluate the effectiveness of a previously proposed optimisation methodology. A total of 36 axial compression tests on CFS channels with three different lengths (1 m, 1.5 m and 2 m) and four different cross-sections were conducted under a concentrically applied load and pin-ended boundary conditions. The initial geometric imperfections of the specimens were measured using a specially designed set-up with laser displacement transducers. Material tests were also carried out to determine the tensile properties of the flat parts of the cross-sections, as well as the cold-worked corner regions. A comparison between the experimental results and the Eurocode 3 predictions showed that the effective width approach combined with the P–M interaction equation proposed in Eurocode 3 to take into account the shift of the effective centroid consistently provided safe results. However, the Eurocode 3 procedures were also quite conservative in predicting the capacity pertaining to local-global interaction buckling, especially for plain channels. Furthermore, the experimental data confirmed the results of an optimisation study and demonstrated that the optimised CFS columns exhibited a capacity which was up to 26% higher than the standard channel with the same amount of material taken as a starting point

Sidewall Buckling of Equal-width RHS Truss X-Joints

This paper presents a new design methodology for equal-width rectangular hollow section (RHS) X-joints failing by sidewall buckling. In the new approach, a slenderness parameter is defined based on the elastic local buckling stress of the sidewall, idealized as an infinitely long plate under patch loading. A Rayleigh-Ritz approximation is thereby used to obtain a closed-form solution. The proposed design equation is verified against experimental results over a wide range of wall slenderness values obtained from the literature and complemented by a brief experimental program carried out by the authors. It is demonstrated that the new design equation yields excellent results against the experimental data. Finally, a reliability analysis is performed within the framework of both the Eurocode and the AISI standards to ensure that the proposed design equation possesses the required level of safety. The newly proposed equation strongly outperforms the current Comité International pour le Développement et l’Etude de la Construction Tubulaire (CIDECT) design rule for sidewall buckling and also further extends the range of applicability to a wall slenderness ratio of up to 50

The interaction of local and overall buckling of cold-formed stainless steel columns.

Abstract: The objective of this research is to investigate the interaction of local and overall flexural buckling in cold-formed stainless steel columns. Literature study exposes a lack of understanding of this subject and a need for experimental data, particularly on the local-overall interaction buckling of stainless steel open sections. Two separate experimental programs were therefore carried out. The first program included 36 tests on pin-ended lipped channel columns. Three alloys were considered: AISI 304, AISI 430 and 3Cr12. The specimens were designed to fail by local-overall interaction buckling in the inelastic stress range, thus highlighting the non-linear behaviour of stainless steel. Half of the specimens were tested under a concentric load. The other half had the load applied with a nominal eccentricity of Le/1500. The test results demonstrate the imperfection sensitivity of local-overall interaction buckling and illustrate the shift in effective centroid in pin-ended columns with singly symmetric cross-section. The second experimental program studied local-overall interaction buckling in 24 pin-ended stainless steel I-section columns. The specimens consisted of plain channels connected back-to-back using sheet metal screws. Two alloys were considered: AISI 304 and AISI 404. Local and overall imperfections were carefully measured in both experimental programs. Extensive material testing was carried out on the alloys employed in the experimental program, in order to determine tensile and compressive material properties, anisotropic parameters and enhanced corner properties. A detailed finite element model is presented, which includes non-linear material behaviour, anisotropy, increased material properties of the corner areas and local and overall imperfections. The model was verified against the two aforementioned experimental programs and against additional data available in literature on stainless steel SHS columns. The model yielded excellent predictions of the specimen failure mode, ultimate strength and load-deformation behaviour. The finite element model was used to generate additional data for stainless steel columns with lipped channel, plain channel, SHS and I-shaped cross-section, failing by local-overall interaction buckling. The parametric studies covered the practical ranges of overall and cross-sectional slenderness values. The Australian/New Zealand, European and North American standards for stainless steel were evaluated using the available data. The comparison reveals an inability of the design codes to properly account for the interaction effect as the cross-sectional slenderness increases. Predictions are unsafe for I-section columns with intermediate or high cross-sectional slenderness. A direct strength method is proposed for stainless steel columns, accounting for the local-overall interaction effect. The method offers a simple design solution which fits within the framework of the current Australian and North-American standards

Local-flexural interactive buckling of standard and optimised cold-formed steel columns

This paper aims to study the interaction of local and overall flexural buckling in cold-formed steel (CFS) channels under axial compression. Detailed nonlinear FE models were developed and validated against a total of 36 axial compression tests on CFS plain and lipped channel columns with pin-ended boundary conditions. The numerical models incorporated the non-linear stress-strain behaviour of CFS material and enhanced properties of cold-worked corner regions obtained from coupon tests. The effects of initial geometric imperfections of the specimens measured by a specially designed set-up with laser displacement transducers were also taken into account. The developed FE models produced excellent predictions of the ultimate strength of the specimens obtained from experimental tests. The validated FE models and experimental results were then used to assess the adequacy of the effective width method in Eurocode 3 (EC3) and Direct Strength Method (DSM) in estimating the design capacity of a wide range of conventional and optimised design CFS channel column sections. The results indicate that Eurocode 3 provides conservative predictions (on average 21% deviation) for the compressive capacity of plain and lipped channel sections, while in general DSM predictions are more accurate for lipped channels. A comparison between FE predictions and tested results show that geometric imperfections can change the FE predictions by up to 20% and 40%, respectively, for lipped and plain channel columns, while the strain hardening effect at the rounded corner regions of the cross-sections is negligible. The results also confirmed that the proposed numerical model is able to provide a consistent and reliable prediction on the efficiency of a previously proposed optimisation methodology

Emollient bath additives for the treatment of childhood eczema (BATHE): multi-centre pragmatic parallel group randomised controlled trial of clinical and cost-effectiveness

Objectives: To determine the clinical and cost-effectiveness of including emollient bath additives in the management of childhood eczema. Trial design: Pragmatic randomised open-label superiority trial with two parallel groups. Setting and recruitment: 96 general practices in Wales, West of England and Southern England. Invitation by personal letter or opportunistically by usual clinical team. Participants: Children were eligible to participate if aged over 12 months and less than 12 years, fulfilling UK Diagnostic Criteria for Atopic Dermatitis. Children with inactive or very mild eczema (5 or less on Nottingham Eczema Severity Scale) were excluded, as were children who bathed less than once a week, or whose carers were not willing to accept randomisation. 483 were randomised and one withdrew, leaving 482 children in the trial: 51% female, 84% white, mean age 5 years. Interventions: The intervention group were prescribed emollient bath additives by their usual clinical team and were asked to use them regularly for 12 months. The control group were asked to use no bath additives for 12 months. Both groups continued with standard eczema management and were given standardised advice on how to wash. Primary outcome: Eczema control measured by Patient Oriented Eczema Measure (POEM, range 0-28) weekly for 16 weeks. Secondary outcomes: Eczema severity over 1 year (4-weekly POEM from baseline to 52 weeks); number of eczema exacerbations resulting in primary healthcare consultation; disease-specific quality of life (QOL) (Dermatitis Family Impact); generic QoL (Child Health Utility-9D); resource utilisation; type and quantity of topical corticosteroid/calcineurin inhibitors prescribed. Randomisation: 483 children were randomised (1:1) using online software, stratified by recruiting centre. Results: 95.6% (461/482) of participants completed at least one post-baseline POEM, so were included in the analysis, and 76.8% (370/482) of participants completed questionnaires for more than 80% of the time points for the primary outcome (12/16 weekly questionnaires to 16 weeks). The mean Baseline POEM was 9.5 (s.d. 5.7) in the bath additives group and 10.1 (s.d. 5.8) in the no bath additives group. The mean POEM over the 16-week period was 7.5 (s.d. 6.0) in the bath additives group and 8.4 (6.0) in the no bath additives group. There was no statistically significant difference in weekly POEM scores between groups over 16 weeks. After controlling for baseline severity and confounders (ethnicity, topical corticosteroid use, soap substitute use) and allowing for clustering of participants within centres and responses within participants over time, POEM scores in the no bath additive group were 0.41 points higher than in the bath additive group (95% CI -0.27 to 1.10), below the published minimal clinically important difference for POEM of 3 points. There was no difference between groups in secondary outcomes, economic outcomes or in adverse effects. Conclusions: This trial found no evidence of clinical benefit from including emollient bath additives in the standard management of childhood eczema. Further research is needed into optimal regimens for leave-on emollient and use of soap substitutes for children with eczema

Fastener behaviour in sheathed light‐gauge steel stud walls under cyclic and monotonic actions

Steel framed buildings using digitally fabricated light-gauge steel sections, combined with an offsite panelised fabrication approach, are becoming more widespread and contribute towards reducing cost and erection time without requiring a large workforce to assemble them. Currently, design standards mandate the use of K- or X-bracing in these structures, thus neglecting the beneficial influence of the sheathing on the behaviour of the system, in particular its resistance to lateral loads. This composite behaviour is largely influenced by the performance of the fasteners, which may exhibit tilting, shear failure and fastener pull-out. This paper takes a first step towards accounting for composite action between light-gauge steel stud framing and calcium silicate board by focusing on the behaviour of the screws connecting both. Key failure modes are identified, based on direct pull-out tests and monotonic and cyclic connector shear tests. Significant pinching behaviour was observed under cyclic excitations