901 research outputs found

    Concave Switching in Single and Multihop Networks

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    Switched queueing networks model wireless networks, input queued switches and numerous other networked communications systems. For single-hop networks, we consider a {(α,g\alpha,g)-switch policy} which combines the MaxWeight policies with bandwidth sharing networks -- a further well studied model of Internet congestion. We prove the maximum stability property for this class of randomized policies. Thus these policies have the same first order behavior as the MaxWeight policies. However, for multihop networks some of these generalized polices address a number of critical weakness of the MaxWeight/BackPressure policies. For multihop networks with fixed routing, we consider the Proportional Scheduler (or (1,log)-policy). In this setting, the BackPressure policy is maximum stable, but must maintain a queue for every route-destination, which typically grows rapidly with a network's size. However, this proportionally fair policy only needs to maintain a queue for each outgoing link, which is typically bounded in number. As is common with Internet routing, by maintaining per-link queueing each node only needs to know the next hop for each packet and not its entire route. Further, in contrast to BackPressure, the Proportional Scheduler does not compare downstream queue lengths to determine weights, only local link information is required. This leads to greater potential for decomposed implementations of the policy. Through a reduction argument and an entropy argument, we demonstrate that, whilst maintaining substantially less queueing overhead, the Proportional Scheduler achieves maximum throughput stability.Comment: 28 page

    Migration, Remittances, Livelihood Trajectories, and Social Resilience

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    Use of natural experimental studies to evaluate 20mph speed limits in two major UK cities.

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    INTRODUCTION: Reductions in traffic speed can potentially offer multiple health and public health benefits. In 2016, implementation of 20mph (30kph) speed limit interventions began in Edinburgh (city-wide) and Belfast (city centre). The aims of this paper are to describe 1) the broad theoretical approach and design of two natural experimental studies to evaluate the 20mph speed limits in Edinburgh and Belfast and 2) how these studies allowed us to test and explore theoretical mechanisms of 20mph speed limit interventions. METHODS: The evaluation consisted of several work packages, each with different research foci, including the political decision-making processes that led to the schemes, their implementation processes, outcomes (including traffic speed, perceptions of safety, and casualties) and cost effectiveness. We used a combination of routinely and locally collected quantitative data and primary quantitative and qualitative data. RESULTS: The evaluation identified many contextual factors influencing the likelihood of 20mph speed limits reaching the political agenda. There were substantial differences between the two sites in several aspects related to implementation. Reductions in speed resulted in significant reductions in collisions and casualties, particularly in Edinburgh, which had higher average speed at baseline. The monetary value of collisions and casualties prevented are likely to exceed the costs of the intervention and thus the overall balance of costs and benefits is likely to be favourable. CONCLUSIONS: Innovative study designs, including natural experiments, are important for assessing the impact of 'real world' public health interventions. Using multiple methods, this project enabled a deeper understanding of not only the effects of the intervention but the factors that explain how and why the intervention and the effects did or did not occur. Importantly it has shown that 20mph speed limits can lead to reductions in speed, collisions and casualties, and are therefore an effective public health intervention

    Developing and implementing 20-mph speed limits in Edinburgh and Belfast : mixed-methods study

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    This project was funded by the National Institute for Health and Care Research (NIHR) Public Health Research programme.Background Transport initiatives such as 20-mph (≈30-km/h) speed limits are anticipated to result in fewer road casualties and improve perceptions of safety, leading to increases in active travel. Lower speeds may also lead to more pleasant environments in which to live, work and play. Objectives The main objective was to evaluate and understand the processes and effects of developing and implementing 20-mph speed limits in Edinburgh and Belfast. The focus was on health-related outcomes (casualties and active travel) that may lead to public health improvements. An additional objective was to investigate the political and policy factors (conditions) that led to the decision to introduce the new speed limits. Design This was a mixed-methods study that comprised an outcome, process, policy and economic evaluation of two natural experiments. Setting The study was set in Edinburgh, Scotland, and Belfast, Northern Ireland, from 2000 to 2018. Participants The whole population of each city were participants, as well as stakeholders involved in implementation and decision-making processes. Intervention The intervention was the implementation of 20-mph legislation, signage, enforcement, and education and awareness-raising in Edinburgh (citywide) and Belfast (city centre). Main outcome measures The main outcomes measured were speed; number, type and severity of road collisions; perceptions; and liveability. Data sources The following data sources were used – routinely and locally collected quantitative data for speed, volume of traffic, casualties and collisions, and costs; documents and print media; surveys; interviews and focus groups; and Google Street View (Google Inc., Mountain View, CA, USA). Results Collisions and casualties – the overall percentage reduction in casualty rates was 39% (the overall percentage reduction in collision rates was 40%) in Edinburgh. The percentage reduction for each level of severity was 23% for fatal casualties, 33% for serious casualties and 37% for minor casualties. In Belfast there was a 2% reduction in casualties, reflecting differences in the size, reach and implementation of the two schemes. Perceptions – in Edinburgh there was an increase in two factors (support for 20 mph and rule-following after implementation) supported by the qualitative data. Liveability – for both cities, there was a small statistical increase in liveability. Speed – mean and median speeds reduced by 1.34 mph and 0.47 mph, respectively, at 12 months in Edinburgh, with no statistically significant changes in Belfast. History, political context, local policy goals, local priorities and leadership influenced decision-making and implementation in the two cities. Limitations There was no analysis of active travel outcomes because the available data were not suitable.  Conclusions The pre-implementation period is important. It helps frame public and political attitudes. The scale of implementation and additional activities in the two cities had a bearing on the impacts. The citywide approach adopted by Edinburgh was effective in reducing speeds and positively affected a range of public health outcomes. The city-centre approach in Belfast (where speeds were already low) was less effective. However, the main outcome of these schemes was a reduction in road casualties at all levels of severity.  Future work Future work should develop a statistical approach to public health interventions that incorporates variables from multiple outcomes. In this study, each outcome was analysed independently of each other. Furthermore, population measures of active travel that can be administered simply, inexpensively and at scale should be developed. Study registration This study is registered as ISRCTN10200526. Funding This project was funded by the National Institute for Health and Care Research (NIHR) Public Health Research programme and will be published in full in Public Health Research; Vol. 10, No. 9. See the NIHR Journals Library website for further project information.Publisher PDFPeer reviewe

    Software Citation Implementation Challenges

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    The main output of the FORCE11 Software Citation working group (https://www.force11.org/group/software-citation-working-group) was a paper on software citation principles (https://doi.org/10.7717/peerj-cs.86) published in September 2016. This paper laid out a set of six high-level principles for software citation (importance, credit and attribution, unique identification, persistence, accessibility, and specificity) and discussed how they could be used to implement software citation in the scholarly community. In a series of talks and other activities, we have promoted software citation using these increasingly accepted principles. At the time the initial paper was published, we also provided guidance and examples on how to make software citable, though we now realize there are unresolved problems with that guidance. The purpose of this document is to provide an explanation of current issues impacting scholarly attribution of research software, organize updated implementation guidance, and identify where best practices and solutions are still needed

    National Survey Of Sea Lice (Lepeophtheirus salmonis Krøyer and Caligus elongatus Nordmann) on Fish Farms in Ireland – 2023

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    Farmed stocks of Atlantic salmon in Ireland are inspected on 14 occasions throughout the year to monitor sea lice levels as part of a national programme. Sea lice are a naturally occurring parasite found on marine fish, including salmonids. They are small ecto-parasitic copepod crustaceans and there are approximately 559 species. The objectives of the National Sea Lice Monitoring Programme are: To provide an objective measurement of infestation levels on farms. To investigate the nature of infestations. To provide management information to drive the implementation of control and management strategies. To facilitate further development and refinement of this strategy. The sea lice control and management strategy has five principal components: Separation of generations. Annual fallowing of sites. Early harvest of two-sea-winter fish. Targeted treatment regimes, including synchronous treatments. Agreed husbandry practices.Marine Institut

    National Survey Of Sea Lice (Lepeophtheirus salmonis Krøyer and Caligus elongatus Nordmann) on Fish Farms in Ireland – 2022

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    Farmed stocks of Atlantic salmon in Ireland are inspected on 14 occasions throughout the year to monitor sea lice levels as part of a national programme. Sea lice are a naturally occurring parasite found on marine fish, including salmonids. They are small ecto-parasitic copepod crustaceans and there are approximately 559 species. The objectives of the National Sea Lice Monitoring Programme are: *To provide an objective measurement of infestation levels on farms. * To investigate the nature of infestations. * To provide management information to drive the implementation of control and management strategies. * To facilitate further development and refinement of this strategy. The sea lice control and management strategy has five principal components: * Separation of generations. * Annual fallowing of sites. * Early harvest of two-sea-winter fish. * Targeted treatment regimes, including synchronous treatments. * Agreed husbandry practices.Marine Institut

    Failure to replicate an association of SNPs in the oxidized LDL receptor gene (OLR1) with CAD

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    Abstract Background The lectin-like oxidized LDL receptor LOX-1 (encoded by OLR1) is believed to play a key role in atherogenesis and some reports suggest an association of OLR1 polymorphisms with myocardial infarction (MI). We tested whether single nucleotide polymorphisms (SNPs) in OLR1 are associated with clinically significant CAD in the Atherosclerotic Disease, VAscular FuNction, & Geneti C Epidemiology (ADVANCE) study. Methods ADVANCE is a population-based case-control study of subjects receiving care within Kaiser Permanente of Northern California including a subset of participants of the Coronary Artery Risk Development in Young Adults (CARDIA) study. We first resequenced the promoter, exonic, and splice site regions of OLR1 and then genotyped four single nucleotide polymorphisms (SNPs), including a non-synonymous SNP (rs11053646, Lys167Asn) as well as an intronic SNP (rs3736232) previously associated with CAD. Results In 1,809 cases with clinical CAD and 1,734 controls, the minor allele of the coding SNP was nominally associated with a lower odds ratio (OR) of CAD across all ethnic groups studied (minimally adjusted OR 0.8, P = 0.007; fully adjusted OR 0.8, P = 0.01). The intronic SNP was nominally associated with an increased risk of CAD (minimally adjusted OR 1.12, p = 0.03; fully adjusted OR 1.13, P = 0.03). However, these associations were not replicated in over 13,200 individuals (including 1,470 cases) in the Atherosclerosis Risk in Communities (ARIC) study. Conclusion Our results do not support the presence of an association between selected common SNPs in OLR1 and the risk of clinical CAD.http://deepblue.lib.umich.edu/bitstream/2027.42/112726/1/12881_2008_Article_317.pd
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