An investigation of the accuracy of finite difference methods in the solution of linear elasticity problems

The accuracy of the finite difference method in the solution of linear elasticity problems that involve either a stress discontinuity or a stress singularity is considered. Solutions to three elasticity problems are discussed in detail: a semi-infinite plane subjected to a uniform load over a portion of its boundary; a bimetallic plate under uniform tensile stress; and a long, midplane symmetric, fiber reinforced laminate subjected to uniform axial strain. Finite difference solutions to the three problems are compared with finite element solutions to corresponding problems. For the first problem a comparison with the exact solution is also made. The finite difference formulations for the three problems are based on second order finite difference formulas that provide for variable spacings in two perpendicular directions. Forward and backward difference formulas are used near boundaries where their use eliminates the need for fictitious grid points

Organic solar cells: electrodes, performance enhancement and degradation mechanisms

In this thesis I focus on a number of aspects associated with the fabrication and characterization of organic photovoltaics. Specifically, my work focuses on evaluating solution processed graphene electrodes for use in organic photovoltaics, improving the performance of indium tin oxide transparent contacts by coating them with Au nanoparticles, and understanding the degradation pathways of Poly(3-hexylthiophene-2,5-diyl): Phenyl-C61-butyric acid methyl ester (P3HT:PCBM) organic solar cells. In my work on graphene electrodes for organic solar cells I worked out a relationship between the sheet resistance and the film transmittance that is useful to optimize such electrodes. Investigation of organic solar cell degradation in a controlled 70-70-70 test (i.e. keeping a device for 70 hours at 70oC under 70% humidity conditions) showed several possible pathways in which the active layer of these photovoltaics degrade. In addition to the typical morphological degradation, a strong increase in paramagnetic defect density in the active layer contributes to their degradation. Formation of paramagnetic defects in P3HT:PCBM layers was attributed by us to the creation of charge transfer complexes between P3HT and oxygen. Our attempts on improving indium tin oxide electrodes for their use in organic photovoltaics included a study of the effects of nucleation of Au-containing molecular nanoclusters. It was discovered that different types of Au nanoparticles with specific properties can be formed by annealing such clusters at different temperatures and under different conditions. This discovery was utilized to fabricate Au nanoparticle layers on indium tin oxide which were then utilized as plasmonic enhancement layers for organic solar cells

Vaping for weight control: Findings from a qualitative study

Introduction: Smokers have expressed concern about weight gain once they stop smoking and weight gain is a risk factor associated with smoking relapse. Nicotine in e-cigarettes, as well as vaping behaviour, may support smoking cessation by reducing weight gain. This study explored the factors that influence attitudes towards, and awareness of, e-cigarettes and weight control post smoking cessation. Methods: Qualitative study involving focus groups with adults in the UK (n = 58) who were either exclusive vapers or dual users. Results: There was limited awareness and/or inclination to vape to prevent weight gain after stopping smoking. Reasons for this centred on: the health gains of stopping smoking outweighing any potential weight gain; a lack of understanding of the appetite supressing effects of nicotine; a belief that vaping could not suppress appetite like a cigarette and could result in craving for certain flavours; concerns about the longer-term effects of e-cigarettes on health and the ethics of promoting vaping as way to support smoking cessation by limiting weight gain, especially for young women. Conclusion: Participants in this study do not appear inclined to use e-cigarettes to prevent weight gain after smoking cessation. There is a lack of understanding about why nicotine might help prevent weight gain and a concern that e-cigarette flavours could provoke cravings and that vaping may be unsafe in the long-term

Bereavement through substance use: findings from an interview study with adults in England and Scotland

Background Deaths associated with alcohol and/or drugs belong to a category of ‘special’ deaths due to three characteristics: traumatic circumstances of the death, stigma directed to both the bereaved and the deceased, and resulting disenfranchised grief experienced by the bereaved. These factors can impede those who are bereaved in this way from both grieving and accessing support. In response to a lack of research in this area this paper reports on an interview study that has aimed to better understand the experiences and needs of this neglected group of bereaved people. Method Interviews with 106 adults (parents, children, spouses, siblings, nieces and friends) bereaved through substance use in Scotland and England. Results Five themes describe interviewee experiences: possibility of death, official processes, stigma, grief and support. These findings suggest what is dominant or unique in this group of bereaved people; namely, that living with substance use (including anticipatory grief), experiencing the subsequent death (often traumatic and stigmatised) and the responses of professionals and others (more likely negative than positive) can disenfranchise grief and negatively impact bereavement and seeking support. Conclusions This article describes a large and unique sample, the largest in the world to be recruited from this population. Our study raises awareness of a hitherto largely ignored and marginalised group of bereaved people, highlighting what might be particular to their bereavement experience and how this may differ from other bereavements, thereby providing an evidence base for improving the availability, level and quality of support. © 2016 Taylor & Franci

Factors associated with the effectiveness and reach of NHS Stop Smoking Services for pregnant women in England

Background The UK National Health Service provides Stop Smoking Services for pregnant women (SSSP) but there is a lack of evidence concerning how these are best organised. This study investigates influences on services’ effectiveness and also on their propensity to engage pregnant smokers with support in stopping smoking. Methods Survey data collected from 121/141 (86%) of SSSP were augmented with data from Hospital Episode Statistics and the 2011 UK National Census. ‘Reach’ or propensity to engage smokers with support was defined as the percentage of pregnant smokers setting a quit date with SSSP support, and ‘Effectiveness’ as the percentage of women who set a quit date who also reported abstinence at four weeks later. A bivariate (i.e. two outcome variable) response Markov Chain Monte Carlo model was used to identify service-level factors associated with the Reach and Effectiveness of SSSP. Results Beta coefficients represent a percentage change in Reach and Effectiveness by the covariate. Providing the majority of one-to-one contacts in a clinic rather than at home increased both Reach (%) (β: 6.97, 95% CI: 3.34, 10.60) and Effectiveness (%) (β: 7.37, 95% CI: 3.03, 11.70). Reach of SSSP was also increased when the population served was more deprived (β for increase in Reach with a one unit increase in IMD score: 0.55, 95% CI: 0.25, 0.85), had a lower proportion of people with dependent children (β: -2.52, 95% CI: -3.82, −1.22), and a lower proportion of people in managerial or professional occupations (β: -0.31, 95% CI: -0.59, −0.03). The Effectiveness of SSSP was decreased in those areas that had a greater percentage of people >16 years with no educational qualifications (β: -0.51, 95% CI: -0.95, −0.07). Conclusions To engage pregnant smokers and to encourage them to quit, it may be more efficient for SSSP support to be focussed around clinics, rather than women’s homes. Reach of SSSP is inversely associated with disadvantage and efforts should be made to contact these women as they are less likely to achieve abstinence in the short and longer term

A qualitative study of e-cigarette emergence and the potential for renormalisation of smoking in UK youth

Background: Growth of e-cigarette use among smokers has raised concerns over uptake by non-smokers, particularly young people. Legislative changes aimed in part at reducing youth exposure to e-cigarettes include the EU Tobacco Products Directive (TPD). A core justification for such measures is the belief that e-cigarettes can lead to tobacco smoking through mechanisms of renormalisation including: mimicking and normalizing the act of smoking; increasing product acceptability via marketing; nicotine exposure. These mechanisms are here explored in relation to findings from qualitative research. Methods: This paper reports results from twenty-one group interviews with 14–15 year olds in Wales, England and Scotland, conducted as part of an ongoing evaluation of the impact of the TPD on youth smoking and e-cigarette use. Interviews were conducted around the end of the transitional period for TPD implementation, and explored perceptions of e-cigarettes and tobacco, as well as similarities and differences between them. Results: Young people differentiated between tobacco and e-cigarettes, rejecting the term e-cigarette in favour of alternatives such as ‘vapes’. Experimental or occasional use was common and generally approved of where occurring within social activity with peers. However, regular use outside of this context was widely disapproved of, unless for the purpose of stopping smoking. Increased prevalence of e-cigarettes did not challenge strongly negative views of smoking or reduce perceived harms caused by it, with disapproval of smoking remaining high. Nicotine use was variable, with flavour a stronger driver for choice of e-liquid, and interest more generally. Conclusion: The extent to which participants differentiated between vaping and smoking, including styles and reasons for use in adults and young people; absence of marketing awareness; and continued strong disapproval of smoking provides limited support for some of the potential mechanisms through which e-cigarettes may renormalise smoking. However caution over nicotine exposure is still necessary

Development of a complex intervention for the maintenance of postpartum smoking abstinence: Process for defining evidence based intervention

Relapse to tobacco smoking for pregnant women that quit is a major public health problem. Evidence based approaches to intervention are urgently required. This study aimed to develop an intervention to be integrated into existing healthcare. A mixed methods approach included a theory driven systematic review identifying promising behaviour change techniques for targeting smoking relapse prevention, and qualitative focus groups and interviews with women, (ex-smokers who had remained quit and those who had relapsed), their partners, and healthcare professionals (N=74). A final stage recruited ten women to refine and initially test a prototype intervention. Our qualitative analysis suggests a lack but need for relapse prevention support. This should be initiated by a trusted ‘credible source’. For many women this would be a midwife or a health visitor. Support needs to be tailored to individual needs, including positive praise/reward, novel digital and electronic support, and partner or social support. Advice and support to use e cigarettes or nicotine replacement therapy for relapse prevention was important for some women, but others remained cautious. The resulting prototype complex intervention includes face to face support reiterated throughout the postpartum period, tailored digital and self-help support, and novel elements such as gifts and NRT

Re-Configuring Identity Postpartum and Sustained Abstinence or Relapse to Tobacco Smoking

Relapse to smoking postpartum is a common and important public health problem. Difficulty in adjusting to a non-smoking identity is a key factor prompting relapse. However, postpartum relapse prevention interventions rarely focus upon offering support for identity change. We conducted an exploratory inductive analysis of a dataset from the Prevention of Return to Smoking Postpartum (PReS) study to understand identity constructs and experiences of pre- and postpartum women (smokers and ex-smokers), partners and health professionals. Data were obtained from 77 unique participants via focus groups, interviews, email or online questionnaires, and were analyzed by two researchers independently, using NVivo 12. Four main themes emerged reflecting identity transition from the pre- to the postpartum period: (i) Pregnancy and the categorization of smoking status; (ii) the disruption of motherhood and loss of self; (iii) adapting to a maternal non-smoking identity; and (iv) factors influencing sustained abstinence versus relapse to smoking. Postpartum relapse prevention interventions need to consider support for women, and the whole family unit, in adjusting to a new identity as a non-smoking mother. Smoking status should be revisited throughout pregnancy and into the postpartum period to aid the long-term integration of smoke-free behavior

Budget 2017: experts respond

First paragraph: The UK chancellor of the exchequer, Philip Hammond, has delivered a budget which offered help to first-time home buyers and the prospect of more money for workers in the National Health Service, but his speech was partly overshadowed by sharpcuts to GDP growth forecastsfrom the Office of Budget Responsibility (OBR). Our team of academics deliver their verdict on the measures introduced and opportunities missed