A study of the entanglement in systems with periodic boundary conditions

We define the local periodic linking number, LK, between two oriented closed or open chains in a system with three-dimensional periodic boundary conditions. The properties of LK indicate that it is an appropriate measure of entanglement between a collection of chains in a periodic system. Using this measure of linking to assess the extent of entanglement in a polymer melt we study the effect of CReTA algorithm on the entanglement of polyethylene chains. Our numerical results show that the statistics of the local periodic linking number observed for polymer melts before and after the application of CReTA are the same.Comment: 11 pages, 11 figure

Prevalence and correlates of achieving recommended physical activity levels among children living in rural South Asia—A multi-centre study

Background: We report the prevalence of recommended physical activity levels (RPALs) and examine the correlates of achieving RPALs in rural South Asian children and analyse its association with anthropometric outcomes. Methods: This analysis on rural South Asian children aged 5–14 years (n = 564) is a part of the Chronic Disease Risk Factor study conducted at three sites in India (Chennai n = 146; Goa n = 218) and Bangladesh (Matlab; n = 200). Data on socio-demographic and lifestyle factors (physical activity (PA); diet) were collected using an interviewer-administered questionnaires, along with objective anthropometric measurements. Multivariate logistic regression models were used to examine whether RPALs (active travel to school (yes/no); leisure-time PA ≥ 1 h/day; sedentary-activity ≤ 2 h/day) were associated with socio-demographic factors, diet and other forms of PA. Multivariate linear regression models were used to investigate associations between RPALs and anthropometrics (BMI- and waist z-scores). Results: The majority of children (71.8 %) belonged to households where a parent had at least a secondary education. Two-thirds (66.7 %) actively travelled to school; 74.6 % reported ≥1 h/day of leisure-time PA and 55.7 % had ≤2 h/day of sedentary-activity; 25.2 % of children reported RPALs in all three dimensions. Older (10–14 years, OR = 2.0; 95 % CI: 1.3, 3.0) and female (OR = 1.7; 95 % CI: 1.1, 2.5) children were more likely to travel actively to school. Leisure-time PA ≥ 1 h/day was more common among boys (OR = 2.5; 95 % CI: 1.5, 4.0), children in Matlab, Bangladesh (OR = 3.0; 95 % CI: 1.6, 5.5), and those with higher processed-food consumption (OR = 2.3; 95 % CI: 1.2, 4.1). Sedentary activity ≤ 2 h/day was associated with younger children (5–9 years, OR = 1.6; 95 % CI: 1.1, 2. 4), children of Goa (OR = 3.5; 95 % CI: 2.1, 6.1) and Chennai (OR = 2.5; 95 % CI: 1.5, 4.3) and low household education (OR = 2.1; 95 % CI: 1.1, 4.1). In multivariate analyses, sedentary activity ≤ 2 h/day was associated with lower BMI-z-scores (β = −0.3; 95 % CI: −0.5, −0.08) and lower waist-z-scores (β = −1.1; 95 % CI: −2.2, −0.07). Conclusion: Only one quarter of children in these rural areas achieved RPAL in active travel, leisure and sedentary activity. Improved understanding of RPAL in rural South Asian children is important due to rapid socio-economic transition

Public health and economic costs of investigating a suspected outbreak of Legionnaires' disease.

This paper provides one of the first assessments of the burden of both the public health investigation and the economic costs associated with an apparent outbreak of Legionnaires' disease (LD) in South East London. In addition to epidemiological, microbiological and environmental investigations, we collected data on the staff time and resources committed by the 11 main organizations responsible for managing the outbreak. Of the overall estimated costs of 455,856 pounds, only 14% (64,264 pounds) was spent on investigation and control of the outbreak compared with 86% (391,592 pounds) spent on the hospital treatment of the patients. The time and money spent on public health services in this investigation appear to represent good value for money considering the potential costs of a major outbreak, including the high case-fatality rate in LD generally and the high health-care costs. Further research is needed to determine optimum strategies for the cost-effective use of health system resources in investigations of LD. Whether the threshold for investigation of cases should be based on observed incidence rates or the cost-effectiveness of investigations, or both, should be debated further

The shock Hugoniot of hydroxy-terminated polybutadiene

The response of polymers to shock loading is becoming of increasing importance, both as binder systems in plastic-bonded explosives (PBXs) and as structural materials in their own right. In this paper, we report on the shock Hugoniot of hydroxy-terminated polybutadiene (HTPB), which is commonly used as a binder system in PBXs, but whose shock response has yet to be presented in the open literature. Results indicate that the shock velocity --- particle velocity relationship is linear, similar to some but not all polymer-based materials

Ultra-processed food consumption and risk of obesity: a prospective cohort study of UK Biobank

Objective: To examine the associations between ultra-processed food consumption and risk of obesity among UK adults. Methods: Participants aged 40-69 years at recruitment in the UK Biobank (2006-2019) with dietary intakes collected using 24-hour recall and repeated measures of adiposity - body mass index (BMI), waist circumference (WC) and percentage of body fat (% BF) - were included (N=22,659; median follow-up: 5 years). Ultra-processed foods were identified using the NOVA classification and their consumption was expressed as a percentage of total energy intake. Multivariable Cox proportional hazards regression models were used to estimate hazard ratios (HR) of several indicators of obesity according to ultra-processed food consumption. Models were adjusted for sociodemographic and lifestyle characteristics. Results: 947 incident cases of overall obesity (BMI≥30 kg/m2) and 1,900 incident cases of abdominal obesity (men: WC≥102cm, women: WC≥88cm) were identified during follow-up. Participants in the highest quartile of ultra-processed food consumption had significantly higher risk of developing overall obesity (HR: 1.79; 95%CI: 1.06─3.03) and abdominal obesity (HR: 1.30; 95%CI: 1.14─1.48). They had higher risk of experiencing a ≥5% increase in BMI (HR: 1.31; 95%CI: 1.20─1.43), WC (HR: 1.35; 95%CI: 1.25─1.45) and %BF (HR: 1.14; 95%CI: 1.03─1.25), than those in the lowest quartile of consumption. Conclusions: Our findings provide evidence that higher consumption of ultra-processed food is strongly associated with a higher risk of multiple indicators of obesity in the UK adult population. Policy makers should consider actions that promote consumption of fresh or minimally processed foods and reduce consumption of ultra-processed foods

Is the Healthy Start scheme associated with increased food expenditure in low-income families with young children in the United Kingdom?

Introduction: Healthy Start is a food assistance programme in the United Kingdom (UK) which aims to provide a nutritional safety-net and enable low-income families on welfare benefits to access a healthier diet through the provision of food vouchers. Healthy Start was launched in 2006 but remains under-evaluated. This study aims to determine whether participation in the Healthy Start scheme is associated with differences in food expenditure in a nationally representative sample of households in the UK. Methods: Cross-sectional analyses of the Living Costs and Food Survey dataset (2010-2017). All households with a child (0-3 years) or pregnant woman were included in the analysis (n=4,869). Multivariable quantile regression compared the expenditure and quantity of fruit and vegetables (FV), infant formula and total food purchases. Four exposure groups were defined based on eligibility, participation and income (Healthy Start Participating, Eligible Non-participating, Nearly Eligible low-income and Ineligible high-income households). Results: Of 876 eligible households, 54% participated in Healthy Start. No significant differences were found in FV or total food purchases between participating and eligible non-participating households, but infant formula purchases were lower in Healthy Start participating households. Ineligible higher-income households had higher purchases of FV. Conclusion: This study did not find evidence of an association between Healthy Start participation and FV expenditure. Moreover, inequalities in FV purchasing persist in the UK. Higher participation and increased voucher value may be needed to improve programme performance and counteract the harmful effects of poverty on diet

Protective Effects of Smoke-free Legislation on Birth Outcomes in England: A Regression Discontinuity Design

Background: Environmental tobacco smoke has an adverse impact on preterm birth and birth weight. England introduced a new law to make virtually all enclosed public places and workplaces smoke free on July 1 2007. We investigated the effect of smoke-free legislation on birth outcomes in England using Hospital Episode Statistics (HES) maternity data. Methods: We used regression discontinuity, a quasi-experimental study design, which can facilitate valid causal inference, to analyse short-term effects of smoke-free legislation on birth weight, low birth weight, gestational age, preterm birth and small for gestational age. Results: We analysed 1,800,906 pregnancies resulting in singleton live-births in England between January 1 2005 and December 31 2009. In the one to five months following the introduction of the smoking-free legislation, for those entering their third trimester, the risk of low birth weight decreased by between 8% (95% CI: 4%-12%) and 14% (95% CI: 5%-23%), very low birth weight between 28% (95% CI: 19%-36%) and 32% (95% CI: 21%-41%), preterm birth between 4% (95% CI: 1%-8%) and 9% (95% CI: 2%-16%), and small for gestational age between 5% (95% CI: 2%-8%) and 9% (95% CI: 2%-15%). The impact of the smoke-free legislation varied by maternal age, deprivation, ethnicity and region. Conclusions: The introduction of smoke-free legislation in England had an immediate beneficial impact on birth outcomes overall, although this benefit was not observed across all age, ethnic, or deprivation groups

Evaluation of the clinical and cost effectiveness of intermediate care clinics for diabetes (ICCD): A multicentre cluster randomised controlled trial

Background Configuring high quality care for the rapidly increasing number of people with type 2 diabetes (T2D) is a major challenge worldwide for both providers and commissioners. In the UK, about two thirds of people with T2D are managed entirely in primary care, with wide variation in management strategies and achievement of targets. Pay for performance, introduced in 2004, initially resulted in improvements but disparities exist in ethnic minorities and the improvements are levelling off. Community based, intermediate care clinics for diabetes (ICCDs) were considered one solution and are functioning across the UK. However, there is no randomised trial evidence for the effectiveness of such clinics. Trial Design, Methods and Findings This is a cluster-randomised trial, involving 3 primary care trusts, with 49 general practices randomised to usual care (n = 25) or intervention (ICCDs; n = 24). All eligible adult patients with T2D were invited; 1997 were recruited and 1280 followed-up after 18-months intervention. Primary outcome: achievement of all three of the NICE targets [(HbA1c≤7.0%/53 mmol/mol; Blood Pressure <140/80 mmHg; cholesterol <154 mg/dl (4 mmol/l)]. Primary outcome was achieved in 14.3% in the intervention arm vs. 9.3% in the control arm (p = 0.059 after adjustment for covariates). The odds ratio (95% CI) for achieving primary outcome in the intervention group was 1.56 (0.98, 2.49). Primary care and community clinic costs were significantly higher in the intervention group, but there were no significant differences in hospital costs or overall healthcare costs. An incremental cost-effectiveness ratio (ICER) of +£7,778 per QALY gained, indicated ICCD was marginally more expensive at producing health gain. Conclusions Intermediate care clinics can contribute to improving target achievement in patients with diabetes. Further work is needed to investigate the optimal scale and organisational structure of ICCD services and whether, over time, their role may change as skill levels in primary care increase. Trial Registration ClinicalTrials.gov NCT00945204; National Research Register (NRR) M0014178167.National Institute of Health Research Project number: SDO/110/2005. Initial service for support costs was provided by Department of health.NHS Leicester City, Thames Valley Diabetes Research Network (TVDRN), West Midlands South Comprehensive Local Research Network (CLRN), Primary Care Research Network (PCRN) and DIERT charity provided additional support for the successful completion of the study

Associations between active travel and adiposity in rural India and Bangladesh: a cross-sectional study.

BACKGROUND: Data on use and health benefits of active travel in rural low- and middle- income country settings are sparse. We aimed to examine correlates of active travel, and its association with adiposity, in rural India and Bangladesh. METHODS: Cross sectional study of 2,122 adults (≥18 years) sampled in 2011-13 from two rural sites in India (Goa and Chennai) and one in Bangladesh (Matlab). Logistic regression was used to examine whether ≥150 min/week of active travel was associated with socio-demographic indices, smoking, oil/butter consumption, and additional physical activity. Adjusting for these same factors, associations between active travel and BMI, waist circumference and waist-to-hip ratio were examined using linear and logistic regression. RESULTS: Forty-six percent of the sample achieved recommended levels of physical activity (≥150 min/week) through active travel alone (range: 33.1 % in Matlab to 54.8 % in Goa). This was more frequent among smokers (adjusted odds ratio 1.36, 95 % confidence interval 1.07-1.72; p = 0.011) and those that spent ≥150 min/week in work-based physical activity (OR 1.71, 1.35-2.16; p < 0.001), but less frequent among females than males (OR 0.25, 0.20-0.31; p < 0.001). In fully adjusted analyses, ≥150 min/week of active travel was associated with lower BMI (adjusted coefficient -0.39 kg/m(2), -0.77 to -0.02; p = 0.037) and a lower likelihood of high waist circumference (OR 0.77, 0.63-0.96; p = 0.018) and high waist-to-hip ratio (OR 0.72, 0.58-0.89; p = 0.002). CONCLUSIONS: Use of active travel for ≥150 min/week was associated with being male, smoking, and higher levels of work-based physical activity. It was associated with lower BMI, and lower risk of a high waist circumference or high waist-to-hip ratio. Promotion of active travel is an important component of strategies to address the growing prevalence of overweight in rural low- and middle- income country settings