111 research outputs found

    GraphCombEx: A Software Tool for Exploration of Combinatorial Optimisation Properties of Large Graphs

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    We present a prototype of a software tool for exploration of multiple combinatorial optimisation problems in large real-world and synthetic complex networks. Our tool, called GraphCombEx (an acronym of Graph Combinatorial Explorer), provides a unified framework for scalable computation and presentation of high-quality suboptimal solutions and bounds for a number of widely studied combinatorial optimisation problems. Efficient representation and applicability to large-scale graphs and complex networks are particularly considered in its design. The problems currently supported include maximum clique, graph colouring, maximum independent set, minimum vertex clique covering, minimum dominating set, as well as the longest simple cycle problem. Suboptimal solutions and intervals for optimal objective values are estimated using scalable heuristics. The tool is designed with extensibility in mind, with the view of further problems and both new fast and high-performance heuristics to be added in the future. GraphCombEx has already been successfully used as a support tool in a number of recent research studies using combinatorial optimisation to analyse complex networks, indicating its promise as a research software tool

    First report of a phytoplasma affecting cassava orchards in Cote d'Ivoire

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    Annex 46 of 48 for CIFSRF-IDRC/GAC Final technical report: http://hdl.handle.net/10625/56415This work was carried out with the aid of a grant from Canada’s International Development Research Centre (IDRC), and with financial support from the Government of Canada, provided through Global Affairs Canada (GAC)This is the first report of a phytoplasma affecting cassava in Côte d'Ivoire. The findings suggest that cassava may be a potential alternative host for the Côte d'Ivoire lethal yellowing (CILY) phytoplasma, which poses a serious threat for the food security of smallholder coconut and cassava farmers, especially women, in Grand-Lahou, Côte d’Ivoire. Leaf samples were collected at random from 12 symptom-bearing and two symptomless cassava plants from two villages. Illustrations/ figures depict the symptoms of yellowing. Cassava (Manihot esculenta) is one of the staple foods in Africa, cultivated in 40 countries and producing more than three million tonnes per year

    Damage evaluation during installation of geosynthetics used in asphalt pavements

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    Geosynthetics are commonly used as anti-reflective cracking systems in asphalt pavements. The rehabilitation design methods use the characteristics of as-received geosynthetics as inputs. However, these materials undergo physical damage during their installation due to mechanical and thermal loads which currently are not taken into account in the design processes. These loads can produce a reduction in geosynthetic strength and therefore, it is necessary to know the secant modulus after installation in order to improve the pavement design incorporating these materials. The secant modulus of a material indicates its initial stiffness. This paper describes an experimental study of damage due to installation of five different geosynthetics using three different procedures: (i) mechanical damage induced in the laboratory considering the action of aggregates, (ii) in situ mechanical and thermal damage due to actual installation in a test section, and (iii) a new mechanical and thermal damage experimental test developed with the aim of reproducing the real installation conditions. The main results of the study indicate that the obtained secant modulus of the tested geosynthetics reduced after applying the three damage procedures, and the loss of properties differed depending on the type and constitutive material and on the applied damage procedure.This investigation was supported by the research Project ‘Rehabilitation of roads and highways (REHABCAR)’ file number IPT-370000–2010–029, led by DRAGADOS (ACS Group), in collaboration with GEOCISA and ASFALTOS AUGUSTA among others. The project has been funded by the Ministry of Economy and Competitiveness (MINECO) within the National Plan for Scientific Research, Development and Innovation 2008–2011 (INNPACTO 2010) and the European Union under ERDF Funds (European Regional Development Fund)

    Potential migratory routes of Urania boisduvalii (Lepidoptera: Uraniidae) among host plant populations

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    This work is licensed under a Creative Commons Attribution 4.0 International License.Aim Migratory species depend on various habitats and resources along their migration routes. Characteristics such as dependence on distinct habitats and the presence of multiple threats along their migratory routes make these species vulnerable, and gaps in knowledge about their ecology and migration processes make them difficult to conserve. Urania boisduvalii is a diurnal moth endemic to Cuba that feeds on plants of Omphalea spp. during its larval phases. These plants produce secondary metabolites as a defence against the moth's larvae, which then are forced to migrate. Although some ecological aspects of Urania boisduvalii are known, its migration routes remain largely unknown. This research proposes potential migratory routes of Urania boisduvalii among populations of its host plant. Location Cuba. Methods We developed ecological niche models of the moth and its hosts based on environmental, anthropic, biotic and biogeographic factors to obtain potential distributional areas that include zones where positive interactions are found but exclude those where negative factors are present. These areas were overlapped to hypothesize potential breeding areas for the moths. Potential migratory corridors were proposed based on environmental connectivity. Results The moth and its hosts have broad potential distributions; however, limiting factors have substantially reduced these areas, especially for plants. The potential migratory routes of Urania boisduvalii are complex and mostly involve the western and eastern regions of Cuba. Most records outside potential breeding areas were close to these migratory corridors. Main conclusions We offer initial hypotheses of the migratory routes of U. boisduvalii, which may be useful to guiding monitoring projects that can provide more definitive views of the seasonal distribution of this species across the Cuban archipelago

    Ministries of Health and the Stewardship of Health Evidence

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    This chapter describes how Ministries of Health have been mandated to act as stewards of populations’ health according to the World Health Organization. We argue that this mandate extends to them having (at least partial) responsibility for ensuring relevant evidence informs policy decisions. Yet this requires consideration of the evidence advisory systems serving Ministry needs, particularly whether or how such systems work to provide relevant information in a timely manner to key decision points in the policy process. Insights from our six cases are presented to illustrate the structural and practical differences which exist between evidence advisory systems and how, at certain times, key health decisions may in fact lie outside ministerial authority. These divergent experiences highlight a range of analytical challenges when considering the provision of evidence to inform health decisions from an institutional perspective

    Differences in the quality of primary medical care for CVD and diabetes across the NHS: evidence from the quality and outcomes framework

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    Background: Health policy in the UK has rapidly diverged since devolution in 1999. However, there is relatively little comparative data available to examine the impact of this natural experiment in the four UK countries. The Quality and Outcomes Framework of the 2004 General Medical Services Contract provides a new and potentially rich source of comparable clinical quality data through which we compare quality of primary medical care for coronary heart disease (CHD), stroke, hypertension and diabetes across the four UK countries. <p/>Methods: A cross-sectional analysis was undertaken involving 10,064 general practices in England, Scotland, Wales and Northern Ireland. The main outcome measures were prevalence rates for CHD, stroke, hypertension and diabetes. Achievement on 14 simple process, 3 complex process, 9 intermediate outcome and 5 treatment indicators for the four clinical areas. <p/>Results: Prevalence varies by up to 28% between the four UK countries, which is not reflected in resource distribution between countries, and penalises practices in the high prevalence countries (Wales and Scotland). Differences in simple process measures across countries are small. Larger differences are found for complex process, intermediate outcome and treatment measures, most notably for Wales, which has consistently lower quality of care. Scotland has generally higher quality than England and Northern Ireland is most consistently the highest quality. <p/>Conclusion: Previously identified weaknesses in Wales related to waiting times appear to reflect a more general quality problem within NHS Wales. Identifying explanations for the observed differences is limited by the lack of comparable data on practice resources and organisation. Maximising the value of cross-jurisdictional comparisons of the ongoing natural experiment of health policy divergence within the UK requires more detailed examination of resource and organisational differences
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