A data-driven Bayesian optimisation framework for the design and stacking sequence selection of increased notched strength laminates

A novel Bayesian optimisation framework is proposed for the design of stronger stacking sequences in composite laminates. The framework is the first to incorporate high-fidelity progressive damage finite element modelling in a data-driven optimisation methodology. Gaussian process regression is used as a surrogate for the finite element model, minimising the number of computationally expensive objective function evaluations. The case of open-hole tensile strength is investigated and used as an example problem, considering typical aerospace design constraints, such as in-plane stiffness, balance of plies and laminate symmetry about the mid-plane. The framework includes a methodology that applies the design constraints without jeopardising surrogate model performance, ensuring that good feasible solutions are found. Three case studies are conducted, considering standard and non-standard angle laminates, and on-axis and misaligned loading, illustrating the benefits of the optimisation framework and its application as a general tool to efficiently establish aerospace design guidelines.</p

Tensile strain mapping in flat germanium membranes

Under the terms of the Creative Commons Attribution (CC BY) license to their work.-- et al.Scanning X-ray micro-diffraction has been used as a non-destructive probe of the local crystalline quality of a thin suspended germanium (Ge) membrane. A series of reciprocal space maps were obtained with ~4 μm spatial resolution, from which detailed information on the strain distribution, thickness, and crystalline tilt of the membrane was obtained. We are able to detect a systematic strain variation across the membranes, but show that this is negligible in the context of using the membranes as platforms for further growth. In addition, we show evidence that the interface and surface quality is improved by suspending the Ge.This work was carried out under the RCUK Basic Technology Programme supported by research Grant Nos. EP/F040784/1, EP/J001074/1, EP/L007010/1, by the European Community's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement NANOFUNCTION No. 257375, by TAPHOR (MAT2012–31392), and by FP7 project MERGING (Grant No. 309150). This research used equipment funded by AWM and ERDF through the Science City Energy Efficiency project.Peer Reviewe

Parental obligations, care and HIV treatment: How care for others motivates self-care in Zimbabwe

This article examines how parental obligations of care intersect with HIV treatment-seeking behaviours and retention. It draws on qualitative data from eastern Zimbabwe, produced from 65 interviews. Drawing on theories of practice and care ethics, our analysis revealed that norms of parental obligation and care acted as key motivators for ongoing engagement with HIV services and treatment. Parents' attentiveness to the future needs of their children ( caring about), and sense of obligation ( taking care of) and improved ability to care ( caregiving) following treatment initiation, emerged as central to understanding their drive for self-care and engagement with HIV services

Providing a conceptual framework for HIV prevention cascades and assessing feasibility of empirical measurement with data from east Zimbabwe: a case study

BACKGROUND: The HIV treatment cascade illustrates the steps required for successful treatment and is a powerful advocacy and monitoring tool. Similar cascades for people susceptible to infection could improve HIV prevention programming. We aim to show the feasibility of using cascade models to monitor prevention programmes. METHODS: Conceptual prevention cascades are described taking intervention-centric and client-centric perspectives to look at supply, demand, and efficacy of interventions. Data from two rounds of a population-based study in east Zimbabwe are used to derive the values of steps for cascades for voluntary medical male circumcision (VMMC) and for partner reduction or condom use driven by HIV testing and counselling (HTC). FINDINGS: In 2009 to 2011 the availability of circumcision services was negligible, but by 2012 to 2013 about a third of the population had access. However, where it was available only 12% of eligible men sought to be circumcised leading to an increase in circumcision prevalence from 3·1% to 6·9%. Of uninfected men, 85·3% did not perceive themselves to be at risk of acquiring HIV. The proportions of men and women tested for HIV increased from 27·5% to 56·6% and from 61·1% to 79·6%, respectively, with 30·4% of men tested self-reporting reduced sexual partner numbers and 12·8% reporting increased condom use. INTERPRETATION: Prevention cascades can be populated to inform HIV prevention programmes. In eastern Zimbabwe programmes need to provide greater access to circumcision services and the design and implementation of associated demand creation activities. Whereas, HTC services need to consider how to increase reductions in partner numbers or increased condom use or should not be considered as contributing to prevention services for the HIV-negative adults. FUNDING: Wellcome Trust and Bill & Melinda Gates Foundation

A Role for the Vacuolating Cytotoxin, VacA, in Colonization and Helicobacter pylori-Induced Metaplasia in the Stomach

Carriage of Helicobacter pylori strains producing more active (s1/i1) forms of VacA is strongly associated with gas-tric adenocarcinoma. To our knowledge, we are the first to determine effects of different polymorphic forms of VacA on inflammation and metaplasia in the mouse stomach. Bacteria producing the less active s2/i2 form of VacA colonized mice more efficiently than mutants null for VacA or producing more active forms of it, providing the first evidence of a positive role for the minimally active s2/i2 toxin. Strains producing more active toxin forms induced more severe and extensive metaplasia and in flammation in the mouse stomach than strains producing weakly active (s2/i2) toxin. We also examined the association in humans, controlling for cag PAI status. In human gastric biopsy specimens, the vacA i1 allele was strongly associated with precancerous intestinal metaplasia, with almost complete absence of intestinal metaplasia in subjects infected with i2-type strains, even in a vacA s1, cagA+ background

Spatial patterns of HIV prevalence and Service Use in East Zimbabwe: implications for future targeting of interventions

Introduction: Focusing resources for HIV control on geographic areas of greatest need in countries with generalised epidemics has been recommended to increase cost-effectiveness. However, socio-economic inequalities between areas of high and low prevalence could raise equity concerns and have been largely overlooked. We describe spatial patterns in HIV prevalence in east Zimbabwe and test for inequalities in accessibility and uptake of HIV services prior to the introduction of spatially-targeted programmes. Methods: 8092 participants in an open-cohort study were geo-located to 110 locations. HIV prevalence and HIV testing and counselling (HTC) uptake were mapped with ordinary kriging. Clusters of high or low HIV prevalence were detected with Kulldorff statistics, and the socio-economic characteristics and sexual risk behaviours of their populations, and levels of local HIV service availability (measured in travel distance) and uptake were compared. Kulldorff statistics were also determined for HTC, antiretroviral therapy (ART), and voluntary medical male circumcision (VMMC) uptake. Results: One large and one small high HIV prevalence cluster (relative risk [RR]=1.78, 95% confidence interval [CI]=1.53–2.07; RR=2.50, 95% CI=2.08–3.01) and one low-prevalence cluster (RR=0.70, 95% CI=0.60–0.82) were detected. The larger high-prevalence cluster was urban with a wealthier population and more high-risk sexual behaviour than outside the cluster. Despite better access to HIV services, there was lower HTC uptake in the high-prevalence cluster (odds ratio [OR] of HTC in past 3 years: OR=0.80, 95% CI=0.66–0.97). The low-prevalence cluster was predominantly rural with a poorer population and longer travel distances to HIV services; however, uptake of HIV services was not reduced. Conclusions: High-prevalence clusters can be identified to which HIV control resources could be targeted. To date, poorer access to HIV services in the poorer low-prevalence areas has not resulted in lower service uptake, while there is significantly lower uptake of HTC in the high-prevalence cluster where health service access is better. Given the high levels of risky sexual behaviour and lower uptake of HTC services, targeting high-prevalence clusters may be cost-effective in this setting. If spatial targeting is introduced, inequalities in HIV service uptake may be avoided through mobile service provision for lower prevalence areas

Compression after impact strength of a buckling resistant, tow steered panel

A novel form of fiber steering (Continuous TowShearing (CTS)) which eliminates manufacturingdefects found in other steered fiber techniques, e.g.tow-overlaps, tow gaps and tow wrinkling, hasrecently been developed. By using CTS to steerfibers in-plane, structures with improved bucklingcapacity can be achieved leading to lower massdesigns. Such optimal designs for minimum massCTS laminates have been produced using the infinitestrip program VICONOPT. The resultingdistribution of fiber orientation and mass across thewidth of these optimized laminates results in regionsof high stress near supports. These regions, whichare vital to the integrity of the CTS laminate, are atrisk of reduction in compressive strength caused byBarely Visible Impact Damage (BVID). Hence,using experimental tests combined with a uniqueanalytical approach, the paper explores the effect ofnear support impact damage on the compressivestrength of CTS panels. Results indicate a failurestrain that matches industrial straight fiberalternatives but that is below the design failurestrain. Hence there is scope for further optimizationof CTS laminates for improved damage tolerance

Stacking sequence selection for defect-free forming of uni-directional ply laminates

In order to meet demands for increased production rates of laminated composite components, aerospace manufacturing is being forced towards highly automated production processes such as forming. However, such automated processes increase the likelihood of inducing defects that lead to manufacturing cost and time inefficiencies which must be avoided. This paper introduces a new compatibility index, based on comparison of minimum energy (resin dominated) modes of adjacent plies that identifies stacking sequences which minimise defect formation. The index is validated using an experimental process where seven laminates with different stacking sequences are formed onto a complex tool geometry using an industrial double diaphragm former. Experimental results confirm that sequences with a high compatibility index produce defect-free parts at elevated temperature. Specifically, sequences with 90° interface angles (high compatibility indices) promote the most formable solutions and continuous 45° interfaces that spiral (e.g. 45/0/-45/90) which have a low compatibility index, produce the most problematic forming conditions owing to a shear locking behaviour. Laminate stacking sequence is thus shown to be a significant contributor, alongside temperature and vacuum rate, to quality of formed parts. The compatibility index method can therefore be used to increase production rate and quality in laminated composite manufacturing, leading to significant cost and efficiency savings.</p

A comparison of single and intersectional social identities associated with discrimination and mental health service use: data from the 2014 Adult Psychiatric Morbidity Survey in England

Inequities in mental health service use (MHSU) and treatment are influenced by social stratification processes linked to socially contextualised interactions between individuals, organisations and institutions. These complex relations underpin observed inequities and their experience by people at the intersections of social statuses. Discrimination is one important mechanism influencing such differences. We compared inequities in MHSU/treatment through single and intersectional status analyses, accounting for need. We assessed whether past-year discrimination differentially influences MHSU/treatment across single and intersecting statuses. Data came from a population survey (collected 2014–2015) nationally representative of English households (N = 7546). We used a theory and datadriven approach (latent class analysis) which identified five intersectional groups in the population comprising common combinations of social statuses. Single status analyses identified characteristics associated with MHSU/treatment (being a sexual minority (adjusted odds ratio (AOR) 1.65 95% CI:1.09-2.50), female (AOR 1.71, 95% CI:1.45–2.02), economically inactive (AOR 2.02, 95% CI:1.05–3.90), in the most deprived quintile (AOR 1.33, 95% CI:1.02–1.74), and Black (AOR 0.36 95% CI:0.20–0.66)). Intersectional analyses detected patterns not apparent from single status analyses. Compared to the most privileged group (“White British, highly educated, employed, high social class”), “Retired WhiteBritish” had greater odds of MHSU/treatment (AOR 1.88, 95% CI:1.53-2.32) while “Employed migrants” had lower odds (AOR 0.39, 95% CI:0.27–0.55). Past-year discrimination was associated with certain disadvantaged social statuses and greater MHSU/treatment but—except for sexual minorities—adjusting for discrimination had little influence using either analytic approach. Observing patterns only by single social statuses masks potentially unanticipated and contextually varying inequities. The latent class approach offers policy-relevant insights into patterns and mechanisms of inequity but may mask other key intersectional patterns by statuses less common or under represented in surveys (e.g. UK-born ethnic minority groups). We propose multiple, context-relevant, theory-driven approaches to intersectional understanding of mental health inequalities