Preliminary analysis of fuel tank impact

Following the accident involving the Air France Concorde in 2000 the effects of fluid structure interactions resulting from the impact of a fluid filled tank has become a cause for concern. The work reported here relates to the design of a series of experiments loosely based upon the Concorde incident which aimed to assess whether the probable failure mode in the Concorde accident could occur in land based vessels. Preliminary numerical analyses were undertaken for two of the nine cases that were investigated experimentally in which an empty tank was impacted by a projectile with a velocity of 14m/s and 21.9m/s Initial numerical results for the acceleration at two points on the tank surface and the deformation at the impact zone showed good agreement with test data. Future work is discussed including further numerical modelling incorporating fluid structure interactions for the analysis of the cases when the tank is partially full or completely full

Effect of breastfeeding on gastrointestinal infection in infants: A targeted maximum likelihood approach for clustered longitudinal data

The PROmotion of Breastfeeding Intervention Trial (PROBIT) cluster-randomized a program encouraging breastfeeding to new mothers in hospital centers. The original studies indicated that this intervention successfully increased duration of breastfeeding and lowered rates of gastrointestinal tract infections in newborns. Additional scientific and popular interest lies in determining the causal effect of longer breastfeeding on gastrointestinal infection. In this study, we estimate the expected infection count under various lengths of breastfeeding in order to estimate the effect of breastfeeding duration on infection. Due to the presence of baseline and time-dependent confounding, specialized "causal" estimation methods are required. We demonstrate the double-robust method of Targeted Maximum Likelihood Estimation (TMLE) in the context of this application and review some related methods and the adjustments required to account for clustering. We compare TMLE (implemented both parametrically and using a data-adaptive algorithm) to other causal methods for this example. In addition, we conduct a simulation study to determine (1) the effectiveness of controlling for clustering indicators when cluster-specific confounders are unmeasured and (2) the importance of using data-adaptive TMLE.Comment: Published in at http://dx.doi.org/10.1214/14-AOAS727 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Fast track children's hearing pilot: final report of the evaluation of the pilot

This report presents key findings of the evaluation of the Fast Track children’s hearings pilot in Scotland1. The research was undertaken by staff at the Universities of Glasgow, Stirling and Strathclyde between February 2003 and January 2005

\u27Traffic-light\u27 nutrition labelling and \u27junk-food\u27 tax : a modelled comparison of cost-effectiveness for obesity prevention

Introduction: Cost-effectiveness analyses are important tools in efforts to prioritise interventions for obesity prevention.Modelling facilitates evaluation of multiple scenarios with varying assumptions. This study compares the cost-effectiveness ofconservative scenarios for two commonly proposed policy-based interventions: front-of-pack &lsquo;traffic-light&rsquo; nutrition labelling(traffic-light labelling) and a tax on unhealthy foods (&lsquo;junk-food&rsquo; tax).Methods: For traffic-light labelling, estimates of changes in energy intake were based on an assumed 10% shift in consumptiontowards healthier options in four food categories (breakfast cereals, pastries, sausages and preprepared meals) in 10% of adults. For the &lsquo;junk-food&rsquo; tax, price elasticities were used to estimate a change in energy intake in response to a 10% price increase in seven food categories (including soft drinks, confectionery and snack foods). Changes in population weight and body mass index by sex were then estimated based on these changes in population energy intake, along with subsequent impacts on disability-adjusted life years (DALYs). Associated resource use was measured and costed using pathway analysis, based on a health sector perspective (with some industry costs included). Costs and health outcomes were discounted at 3%. The cost-effectiveness of each intervention was modelled for the 2003 Australian adult population.Results: Both interventions resulted in reduced mean weight (traffic-light labelling: 1.3 kg (95% uncertainty interval (UI): 1.2;1.4); &lsquo;junk-food&rsquo; tax: 1.6 kg (95% UI: 1.5; 1.7)); and DALYs averted (traffic-light labelling: 45 100 (95% UI: 37 700; 60 100);&lsquo;junk-food&rsquo; tax: 559 000 (95% UI: 459 500; 676 000)). Cost outlays were AUD81 million (95% UI: 44.7; 108.0) for traffic-lightlabelling and AUD18 million (95% UI: 14.4; 21.6) for &lsquo;junk-food&rsquo; tax. Cost-effectiveness analysis showed both interventions were&lsquo;dominant&rsquo; (effective and cost-saving).Conclusion: Policy-based population-wide interventions such as traffic-light nutrition labelling and taxes on unhealthy foods arelikely to offer excellent &lsquo;value for money&rsquo; as obesity prevention measures.<br /

Economic Evaluation Plan (EEP) for A Very Early Rehabilitation Trial (AVERT): An international trial to compare the costs and cost-effectiveness of commencing out of bed standing and walking training (very early mobilization) within 24 h of stroke onset with usual stroke unit care

Rationale: A key objective of A Very Early Rehabilitation Trial is to determine if the intervention, very early mobilisation following stroke, is cost-effective. Resource use data were collected to enable an economic evaluation to be undertaken and a plan for the main economic analyses was written prior to the completion of follow up data collection. Aim and hypothesis To report methods used to collect resource use data, pre-specify the main economic evaluation analyses and report other intended exploratory analyses of resource use data. Sample size estimates: Recruitment to the trial has been completed. A total of 2,104 participants from 56 stroke units across three geographic regions participated in the trial. Methods and design: Resource use data were collected prospectively alongside the trial using standardised tools. The primary economic evaluation method is a cost-effectiveness analysis to compare resource use over 12 months with health outcomes of the intervention measured against a usual care comparator. A cost-utility analysis is also intended. Study outcome: The primary outcome in the cost-effectiveness analysis will be favourable outcome (modified Rankin Scale score 0-2) at 12 months. Cost-utility analysis will use health-related quality of life, reported as quality-adjusted life years gained over a 12 month period, as measured by the modified Rankin Scale and the Assessment of Quality of Life. Discussion: Outcomes of the economic evaluation analysis will inform the cost-effectiveness of very early mobilisation following stroke when compared to usual care. The exploratory analysis will report patterns of resource use in the first year following stroke

A Flexible Semi-Parametric Approach to Estimating a Dose-Response Relationship: the Treatment of Childhood Amblyopia.

In a study of a dose-response relationship, flexibility in modelling is essential to capturing the treatment effect when the mean effect of other covariates is not fully understood, so that observed treatment effect is not due to the imposition of a rigid model for the relationship between response, treatment, and other variables. A semiparametric additive linear mixed (SPALM) model (Ruppert et al. 2003) provides a tractable and flexible approach to modelling the influence of potentially confounding variables. In this paper, we present pure likelihood and Bayesian versions of the SPALM model. Both methods of inference are readily implementable, but the Bayesian approach allows coherent propagation of uncertainty in the model, and, more importantly, allows prediction of future experimental results for as yet untreated individuals, thus allowing an assessment of the merits of different dosing strategies. We motivate the use of the methodology with the Monitored Occlusion Treatment of Amblyopia Study (MOTAS), which investigated the relationship between duration of occlusion and improvement in visual acuity

Design and Performance of Lift-Offset Rotorcraft for Short-Haul Missions

The design and performance of compound helicopters utilizing lift-offset rotors are examined, in the context of short-haul, medium-size civil and military missions. The analysis tools used are the comprehensive analysis CAMRAD II and the sizing code NDARC. Following correlation of the comprehensive analysis with existing lift-offset aircraft flight test data, the rotor performance model for the sizing code was developed, and an initial estimate was made of the rotor size and key hover and cruise flight conditions. The rotor planform and twist were optimized for those conditions, and the sizing code rotor performance model updated. Two models for estimating the blade and hub weight of lift-offset rotors are discussed. The civil and military missions are described, along with the aircraft design assumptions. The aircraft are sized for 30 passengers or 6600 lb payload, with a range of 300 nm. Civil and military aircraft designs are described for each of the rotor weight models. Disk loading and blade loading were varied to optimize the designs, based on gross weight and fuel burn. The influence of technology is shown, in terms of rotor hub drag and rotor weight