3,781 research outputs found

    Active Metamaterials with Negative Static Electric Susceptibility

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    Although well‐established textbook arguments suggest that static electric susceptibility χ(0) must be positive in “all bodies,” it has been pointed out that materials that are not in thermodynamic equilibrium are not necessarily subject to this restriction. Media with inverted populations of atomic and molecular energy levels have been predicted theoretically to exhibit a χ(0) < 0 state, however the systems envisioned require reduced temperature, reduced pressure, and an external pump laser to maintain the population inversion. Further, the existence of χ(0) < 0 has never been confirmed experimentally. Here, a completely different approach is taken to the question of χ(0) < 0 and a design concept to achieve “true” χ(0) < 0 is proposed based on active metamaterials with internal power sources. Two active metamaterial structures are fabricated that, despite still having their power sources implemented externally for reasons of practical convenience, provide evidence in support of the general concept. Effective values are readily achieved at room temperature and pressure and are tunable throughout the range of stability −1 < χ(0) < 0, resulting in experimentally‐determined magnitudes that are over one thousand times greater than those predicted previously. Since χ(0) < 0 is the missing electric analog of diamagnetism, this work opens the door to new technological capabilities such as stable electrostatic levitation

    The College News, 1936-04-08, Vol. 22, No. 19

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    Bryn Mawr College student newspaper. Merged with The Haverford News in 1968 to form the Bi-college News (with various titles from 1968 on). Published weekly (except holidays) during the academic year

    Intelligent transport systems: the propensity for environmental and economic benefits

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    Whilst the economic and efficiency benefits of Intelligent Transport Systems (ITS) are well established, the goal of this research is to demonstrate the simultaneous propensity for low carbon benefits through the deployment of ITS. The foundation of this paper is therefore that the deployment of these technology measures contributes to the positive-sum game of both economic and environmental sustainability. Two research questions are addressed: firstly whether the evidence supports the notion that ITS systems can be implemented and operated in such a way to generate environmental benefits; and secondly whether policy priorities amongst national and international stakeholders reflect a propensity for ITS deployment in order to yield those benefits. The first question is addressed using a rationale based upon both underlying drivers and a synthesis of the empirical evidence. The second is addressed by the development of novel propensity models using primary research on international stakeholders' perceptions of ITS as a priority solution to deliver climate and environmental goals. The research shows that Vehicle Density and High Technology exports were found to be significant variables in determining the propensity for ITS to feature as a high priority policy tool in future transport strategies. The research holds further value in positioning ITS as a policy tool able to deliver both economic and sustainability gains. It holds relevance for both policy analysts and transport strategists at international, national and regional tiers

    Insights on Māori Social Enterprise 2017- Pakihi What Kaupapa

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    Te Puni Kōkiri would like to thank Maui Lab at the University of Canterbury and acknowledge with much appreciation the intelligence provided by the Research report: Māori Social Enterprise – A preliminary scoping and needs analysis (unpublished). In particular, a mihi to the lead author Sacha McMeeking, supported by William Grant and Unaiki Melrose. We also wish to thank Ākina, Maori Womens Development Inc. and Dovetail for their contribution to Te Hiringa Hononga Community Social Enterprise Programme and the findings from the Programme that have contributed to this resource. And finally, we wish to particularly acknowledge all the Māori social entrepreneurs who contributed their journeys and insights for the resource. We also wish to acknowledge Te Pūtahitanga o Te Waipounamu who allowed Maui Lab to draw upon insights into Māori social enterprise gained while working with the kaupapa they have supported.This resource has been prepared by Te Puni Kōkiri to provide insight and share initial findings from Te Puni Kōkiri commissioned research and evaluation of Māori social enterprise in Aotearoa. These insights are intended to contribute to a wider discussion around the kinds of supports the Government should focus on and invest in to grow Māori social enterprise, as part of its commitment to He kai kei aku ringa – the Crown-Māori Economic Growth Partnership. The insights in this report are primarily sourced from: › Māori Social Enterprise – A preliminary scoping and needs analysis completed for Te Puni Kōkiri by Maui Lab at the University of Canterbury (unpublished). The lead author is Sacha McMeeking, supported by William Grant and Unaiki Melrose. This report was commissioned to better understand what Māori social enterprise is in Aotearoa and inform key stakeholders about designing programmes and policy settings that could support Māori social enterprise development. › Te Hiringa Hononga Community Social Enterprise Programme: 2017 Evaluation Report (unpublished). Prepared by Dr Adrian Field, Debbie Goodwin and Louise Were. Te Hiringa Hinonga Community Social Enterprise Programme was an investment pilot initiative to build the capability of Māori social enterprises in Te Tairāwhiti and Te Taitokerau in 2016/17. The pilot was trialled in both regions, of which have high Māori populations to support the growth of Māori social enterprise capability

    Effective use of excess capacity for low carbon urban transport futures

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    A reduction in emissions from transport is essential and requires a system wide approach, inclusive of technological and behavioural changes. Defining capacity in urban transport as the space through which transport demand can be met, the research explores where there is excess capacity in the system and how this could be used to reduce emissions. Capacity may be physical capacity in the roadspace or seats within vehicles, or temporal capacity, where there are fluctuations in the use of the system, such as peak and off-peak flows. This is complementary to the International Energy Agency (IEA)’s definition of urban transport energy efficiency as maximising travel activity whilst minimising energy consumption through a range of approaches and techniques. This paper proposes that interventions designed to enable behavioural change could reduce emissions by changing the way that the urban transport system is used. Drawing on the literature, this work demonstrates how effective use of excess capacity might be facilitated through measures such as smarter choices programmes and the application of intelligent transport systems (ITS). Case studies are provided as examples of ways that urban transport infrastructure can be adapted for more efficient use, including shared space projects and the ‘complete streets’ policy in New York City. The paper concludes by presenting the potential impacts of effective use of excess capacity for reducing urban transport emissions as demonstrated through the case studies

    Aspirin, clopidogrel and prasugrel monotherapy in patients with type 2 diabetes mellitus: a double-blind randomised controlled trial of the effects on thrombotic markers and microRNA levels

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    Background: Despite increased atherothrombotic risk in type 2 diabetes mellitus, (T2DM) the best preventative antithrombotic strategy remains undetermined. We defined the effects of three antiplatelet agents on functional readout and biomarker kinetics in platelet activation and coagulation in patients with T2DM. Materials and methods: 56 patients with T2DM were randomised to antiplatelet monotherapy with aspirin 75 mg once daily (OD), clopidogrel 75 mg OD or prasugrel 10 mg OD during three periods of a crossover study. Platelet aggregation (PA) was determined by light-transmittance aggregometry and P-selectin expression by flow cytometry. Markers of fibrin clot dynamics, inflammation and coagulation were measured. Plasma levels of 14 miRNA were assessed by quantitative polymerase chain reactions. Results: Of the 56 patients, 24 (43%) were receiving aspirin for primary prevention of ischaemic events and 32 (57%) for secondary prevention. Prasugrel was the strongest inhibitor of ADP-induced PA (mean ± SD maximum response to 20μmol/L ADP 77.6 ± 8.4% [aspirin] vs. 57.7 ± 17.6% [clopidogrel] vs. 34.1 ± 14.1% [prasugrel], p < 0.001), P-selectin expression (30 μmol/L ADP; 45.1 ± 21.4% vs. 27.1 ± 19.0% vs. 14.1 ± 14.9%, p < 0.001) and collagen-induced PA (2 μg/mL; 62.1 ± 19.4% vs. 72.3 ± 18.2% vs. 60.2 ± 18.5%, p < 0.001). Fibrin clot dynamics and levels of coagulation and inflammatory proteins were similar. Lower levels of miR-24 (p = 0.004), miR-191 (p = 0.019), miR-197 (p = 0.009) and miR-223 (p = 0.014) were demonstrated during prasugrel-therapy vs. aspirin. Circulating miR-197 was lower in those cardiovascular disease during therapy with aspirin (p = 0.039) or prasugrel (p = 0.0083). Conclusions: Prasugrel monotherapy in T2DM provided potent platelet inhibition and reduced levels of a number of platelet-associated miRNAs. miR-197 is a potential marker of cardiovascular disease in this population. Clinical outcome studies investigating prasugrel monotherapy are warranted in individuals with T2DM. Trial registration: EudraCT, 2009-011907-22. Registered 15 March 2010, https://www.clinicaltrialsregister.eu/ctr-search/trial/2009-011907-22/GB

    Improved prediction of postoperative paediatric cerebellar mutism syndrome using an artificial neural network

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    BACKGROUND: Postoperative paediatric cerebellar mutism syndrome (pCMS) is a common but severe complication which may arise following the resection of posterior fossa tumours in children. Two previous studies have aimed to preoperatively predict pCMS, with varying results. In this work, we examine the generalisation of these models and determine if pCMS can be predicted more accurately using an artificial neural network (ANN). METHODS: An overview of reviews was performed to identify risk factors for pCMS, and a retrospective dataset collected as per these defined risk factors from children undergoing resection of primary posterior fossa tumours. The ANN was trained on this dataset and its performance evaluated in comparison to logistic regression and other predictive indices via analysis of receiver operator characteristic curves. Area under the curve (AUC) and accuracy were calculated and compared using a Wilcoxon signed rank test, with p<0.05 considered statistically significant. RESULTS: 204 children were included, of whom 80 developed pCMS. The performance of the ANN (AUC 0.949; accuracy 90.9%) exceeded that of logistic regression (p<0.05) and both external models (p<0.001). CONCLUSION: Using an ANN, we show improved prediction of pCMS in comparison to previous models and conventional methods

    Who bullies whom at a garden feeder? Interspecific agonistic interactions of small passerines during a cold winter

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    Interspecific agonistic interactions are important selective factors for maintaining ecological niches of different species, but their outcome is difficult to predict a priori. Here, we examined the direction and intensity of interspecific interactions in an assemblage of small passerines at a garden feeder, focussing on three finch species of various body sizes. We found that large and mediumsized birds usually initiated and won agonistic interactions with smaller species. Also, the frequency of fights increased with decreasing differences in body size between the participants. Finally, the probability of engaging in a fight increased with the number of birds at the feeder

    A re-appraisal of the reliability of the 20 m multi-stage shuttle run test

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    This is the author's PDF version of an article published in European journal of applied physiology in 2007. The original publication is available at www.springerlink.co

    Cytotaxonomic characterization and estimation of migration patterns of onchocerciasis vectors (Simulium damnosum sensu lato) in northwestern Ethiopia based on RADSeq data

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    While much progress has been made in the control and elimination of onchocerciasis across Africa, the extent to which vector migration might confound progress towards elimination or result in re-establishment of endemism in areas where transmission has been eliminated remains unclear. In Northern Ethiopia, Metema and Metekel-two foci located near the Sudan border-exhibit continuing transmission. While progress towards elimination has been faster in Metema, there remains a problematic hotspot of transmission. Whether migration from Metekel contributes to this is currently unknown. To assess the role of vector migration from Metekel into Metema, we present a population genomics study of 151 adult female vectors using 47,638 RADseq markers and mtDNA CoI sequencing. From additional cytotaxonomy data we identified a new cytoform in Metema, closely related to S. damnosum s.str, here called the Gondar form. RADseq data strongly indicate the existence of two distinctly differentiated clusters within S. damnosum s.l.: one genotypic cluster found only in Metema, and the second found predominantly in Metekel. Because blackflies from both clusters were found in sympatry (in all four collection sites in Metema), but hybrid genotypes were not detected, there may be reproductive barriers preventing interbreeding. The dominant genotype in Metema was not found in Metekel while the dominant genotype in Metekel was found in Metema, indicating that (at the time of sampling) migration is primarily unidirectional, with flies moving from Metekel to Metema. There was strong differentiation between clusters but little genetic differentiation within clusters, suggesting migration and gene flow of flies within the same genetic cluster are sufficient to prevent genetic divergence between sites. Our results confirm that Metekel and Metema represent different transmission foci, but also indicate a northward movement of vectors between foci that may have epidemiological importance, although its significance requires further study
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