420 research outputs found

    Self-similar Solutions to a Kinetic Model for Grain Growth

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    We prove the existence of self-similar solutions to the Fradkov model for two-dimensional grain growth, which consists of an infinite number of nonlocally coupled transport equations for the number densities of grains with given area and number of neighbours (topological class). For the proof we introduce a finite maximal topological class and study an appropriate upwind-discretization of the time dependent problem in self-similar variables. We first show that the resulting finite dimensional differential system has nontrivial steady states. Afterwards we let the discretization parameter tend to zero and prove that the steady states converge to a compactly supported self-similar solution for a Fradkov model with finitely many equations. In a third step we let the maximal topology class tend to infinity and obtain self-similar solutions to the original system that decay exponentially. Finally, we use the upwind discretization to compute self-similar solutions numerically.Comment: 25 pages, several figure

    The Economic Costs of Cardiovascular Disease, Diabetes Mellitus, and Associated Complications in South Asia: A Systematic Review

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    Background: More than 80% of global deaths caused by cardiovascular disease (CVD) and diabetes mellitus (DM) occur in developing countries. The burden of noncommunicable disease in South Asia is increasing rapidly. Objectives: To estimate the costs of CVD and the costs of DM to individuals and society in Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka. Methods: We systematically searched six health and economic databases for studies identifying costs related to CVD or DM and their respective complications. Costs were extracted from included studies and converted to US $ for the price year 2015 to enable meaningful comparisons. Results: Of the 71 articles suitable for full-text review, 29 studies met the inclusion criteria. Most were cost-of-illness studies (n = 27) and were from the patient perspective (n = 23). Most collected data since 2000 (n = 23) and included data from India (n = 24). No studies included longitudinal costs at the patient level. Medical costs for routine management of CVD and DM were broadly similar. These costs escalate significantly once complications occur, which require treatment, particularly for stroke, major coronary events, and amputations. Costs are mainly borne by the individual and family. Some included studies modeled rapidly rising future costs. Most studies included had methodological weaknesses. Conclusions: Marked increases in costs have been identified when complications of these chronic diseases occur, underlining the importance of secondary prevention approaches in disease management in South Asia. Higher quality studies, especially those that include longitudinal costs, are required to establish more robust cost estimates

    Assessing the impact of care farms on quality of life and offending: a pilot study among probation service users in England

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    OBJECTIVES: To assess the feasibility of conducting a cost-effectiveness study of using care farms (CFs) to improve quality of life and reduce reoffending among offenders undertaking community orders (COs). To pilot questionnaires to assess quality of life, connection to nature, lifestyle behaviours, health and social-care use. To assess recruitment and retention at 6 months and feasibility of data linkage to Police National Computer (PNC) reconvictions data and data held by probation services. DESIGN: Pilot study using questionnaires to assess quality of life, individually linked to police and probation data. SETTING: The pilot study was conducted in three probation service regions in England. Each site included a CF and at least one comparator CO project. CFs are working farms used with a range of clients, including offenders, for therapeutic purposes. The three CFs included one aquaponics and horticulture social enterprise, a religious charity focusing on horticulture and a family-run cattle farm. Comparator projects included sorting secondhand clothes and activities to address alcohol misuse and anger management. PARTICIPANTS: We recruited 134 adults (over 18) serving COs in England, 29% female. RESULTS: 52% of participants completed follow-up questionnaires. Privatisation of UK probation trusts in 2014 negatively impacted on recruitment and retention. Linkage to PNC data was a more successful means of follow-up, with 90% consenting to access their probation and PNC data. Collection of health and social-care costs and quality-adjusted life year derivation were feasible. Propensity score adjustment provided a viable comparison method despite differences between comparators. We found worse health and higher reoffending risk among CF participants due to allocation of challenging offenders to CFs, making risk of reoffending a confounder. CONCLUSIONS: Recruitment would be feasible in a more stable probation environment. Follow-up was challenging; however, assessing reconvictions from PNC data is feasible and a potential primary outcome for future studies

    Community engagement interventions for communicable disease control in low- and lower- middle-income countries : evidence from a review of systematic reviews

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    BACKGROUND: Community engagement (CE) interventions include a range of approaches to involve communities in the improvement of their health and wellbeing. Working with communities defined by location or some other shared interest, these interventions may be important in assisting equity and reach of communicable disease control (CDC) in low and lower-middle income countries (LLMIC). We conducted an umbrella review to identify approaches to CE in communicable disease control, effectiveness of these approaches, mechanisms and factors influencing success. METHODS: We included systematic reviews that: i) focussed on CE interventions; ii) involved adult community members; iii) included outcomes relevant to communicable diseases in LLMIC; iv) were written in English. Quantitative results were extracted and synthesised narratively. A qualitative synthesis process enabled identification of mechanisms of effect and influencing factors. We followed guidance from the Joanna Briggs Institute, assessed quality with the DARE tool and reported according to standard systematic review methodology. RESULTS: Thirteen systematic reviews of medium-to-high quality were identified between June and July 2017. Reviews covered the following outcomes: HIV and STIs (6); malaria (2); TB (1); child and maternal health (3) and mixed (1). Approaches included: CE through peer education and community health workers, community empowerment interventions and more general community participation or mobilisation. Techniques included sensitisation with the community and involvement in the identification of resources, intervention development and delivery. Evidence of effectiveness of CE on health outcomes was mixed and quality of primary studies variable. We found: i) significantly reduced neonatal mortality following women's participatory learning and action groups; ii) significant reductions in HIV and other STIs with empowerment and mobilisation interventions with marginalised groups; iii) significant reductions in malaria incidence or prevalence in a small number of primary studies; iv) significant reductions in infant diarrhoea following community health worker interventions. Mechanisms of impact commonly occurred through social and behavioural processes, particularly: changing social norms, increasing social cohesion and social capacity. Factors influencing effectiveness of CE interventions included extent of population coverage, shared leadership and community control over outcomes. CONCLUSION: Community engagement interventions may be effective in supporting CDC in LLMIC. Careful design of CE interventions appropriate to context, disease and community is vital

    Size does matter: crocodile mothers react more to the voice of smaller offspring

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    Parental care is widespread in Archosaurs (birds, crocodilians, dinosaurs and pterosaurs), and this group provides a useful model for the evolution of parent-offspring interactions. While offspring signalling has been well-studied in birds, the modulation of parental care in crocodilians remains an open question. Here we show that acoustic communication has a key role in the dynamics of crocodilian’ mother-offspring relationships. We found embedded information about the emitter’s size in juvenile calls of several species, and experimentally demonstrated that Nile crocodile mothers breeding in the wild are less receptive to the calls of larger juveniles. Using synthetized sounds, we further showed that female’ reaction depends on call pitch, an important cue bearing size information. Changes in acoustic interactions may thus go with the break of maternal care as well as dispersal of juvenile crocodilians. This process could have characterized other archosaurs displaying rapid early growth such as dinosaurs and pterosaurs

    Addressing Inequities in Urban Health: Do Decision-Makers Have the Data They Need? Report from the Urban Health Data Special Session at International Conference on Urban Health Dhaka 2015

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    Rapid and uncontrolled urbanisation across low and middle-income countries is leading to ever expanding numbers of urban poor, defined here as slum dwellers and the homeless. It is estimated that 828 million people are currently living in slum conditions. If governments, donors and NGOs are to respond to these growing inequities they need data that adequately represents the needs of the urban poorest as well as others across the socio-economic spectrum. We report on the findings of a special session held at the International Conference on Urban Health, Dhaka 2015. We present an overview of the need for data on urban health for planning and allocating resources to address urban inequities. Such data needs to provide information on differences between urban and rural areas nationally, between and within urban communities. We discuss the limitations of data most commonly available to national and municipality level government, donor and NGO staff. In particular we assess, with reference to the WHO’s Urban HEART tool, the challenges in the design of household surveys in understanding urban health inequities. We then present two novel approaches aimed at improving the information on the health of the urban poorest. The first uses gridded population sampling techniques within the design and implementation of household surveys and the second adapts Urban HEART into a participatory approach which enables slum residents to assess indicators whilst simultaneously planning the response. We argue that if progress is to be made towards inclusive, safe, resilient and sustainable cities, as articulated in Sustainable Development Goal 11, then understanding urban health inequities is a vital pre-requisite to an effective response by governments, donors, NGOs and communities

    Analysis of loss to follow-up in 4099 multidrug-resistant pulmonary tuberculosis patients

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    Loss to follow-up (LFU) of 2 consecutive months contributes to the poor levels of treatment success in multidrug-resistant tuberculosis (MDR-TB) reported by TB programmes. We explored the timing of when LFU occurs by month of MDR-TB treatment and identified patient-level risk factors associated with LFU. We analysed a dataset of individual MDR-TB patient data (4099 patients from 22 countries). We used Kaplan–Meier survival curves to plot time to LFU and a Cox proportional hazards model to explore the association of potential risk factors with LFU. Around one-sixth (n=702) of patients were recorded as LFU. Median (interquartile range) time to LFU was 7 (3–11) months. The majority of LFU occurred in the initial phase of treatment (75% in the first 11 months). Major risk factors associated with LFU were: age 36–50 years (HR 1.3, 95% CI 1.0–1.6; p=0.04) compared with age 0–25 years, being HIV positive (HR 1.8, 95% CI 1.2–2.7; p<0.01) compared with HIV negative, on an individualised treatment regimen (HR 0.7, 95% CI 0.6–1.0; p=0.03) compared with a standardised regimen and a recorded serious adverse event (HR 0.5, 95% CI 0.4–0.6; p<0.01) compared with no serious adverse event. Both patient- and regimen-related factors were associated with LFU, which may guide interventions to improve treatment adherence, particularly in the first 11 months
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