909 research outputs found

    A first broad-scale molecular phylogeny of Prionoceridae (Coleoptera: Cleroidea) provides insight into taxonomy, biogeography and life history evolution

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    © Senckenberg Gesellschaft fur Naturforschung, 2016. This is an open access article. Authors are permitted to post a PDF of their own articles, as provided by the publisher, on their personal web pages or the web page of their institution. Any commercial use is excluded. The attached file is the published version of the article

    The Effect Of Pitting Corrosion On The Position Of Aircraft Structural Failures

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    Corrosion has been shown over the last decade to significantly reduce the structural integrity of aircraft as they age. Previous work at DSTO has shown that pitting and exfoliation corrosion are particularly deleterious to aircraft structural integrity. In addition to reducing fatigue endurance, pitting also increases the surface area of the component over which fatigue failures can occur. This paper reports the results of a Monte-Carlo model of this phenomenon, which has been labelled 'corrosion criticality'. This model concentrates on the effect of the pit spatial density and position on the endurance of a fatigue coupon designed to mimic a simple aircraft component. The study's results show that pitting increases the area of the coupon over which failures can occur

    Providing marketing information to smallholders in Zimbabwe: What can the state usefully do?

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    In recent decades, significant international assistance has been provided to assist the establishment of market information systems (MISs) in a range of developing countries, including many in Africa. However, experience with state-run MISs, looking to provide current price information to market participants, has not been encouraging. Volatile horticultural markets provide particular challenges for such MISs. Therefore, it is suggested that it might be more appropriate to provide other types of marketing information to inform the production and marketing decisions of smallholder producers. This paper reports on recent efforts by the national extension agency, Agritex, to provide such information to smallholder horticultural producers in two districts of north-eastern Zimbabwe. Drawing on an initial evaluation of this pilot programme, the paper suggests that: 1) in the Zimbabwe case, the extension service may provide a viable vehicle for dissemination of marketing information to smallholder (horticultural) producers; 2) information on new crops and market opportunities is valued more highly by farmers than information on current market prices; 3) such information should complement, not supplant, traditional production extension advice. The paper concludes by considering some of the issues pertaining to the continuation and expansion of the pilot programme.Marketing,

    A New Species of \u3cem\u3eCallulina\u3c/em\u3e (Anura: Microhylidae) from the West Usambara Mountains, Tanzania

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    The description of the species Callulina kreffti was based on specimens collected in the East Usambara Mountains of Tanzania. Successive collecting has shown this species to be widely distributed through the Eastern Arc Mountains. Advertisement calls from populations in the type locality of Callulina kreffti were compared with calls from populations in the West Usambara Mountains. Analysis of the calls suggested that these two populations of Callulina represent two separate taxa. Subsequent morphological and molecular investigations indicated that these two populations are distinct. Herein, we describe a new Callulina species on the basis of call, morphology and molecular sequences

    Toad radiation reveals into-India dispersal as a source of endemism in the Western Ghats-Sri Lanka biodiversity hotspot

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    <p>Abstract</p> <p>Background</p> <p>High taxonomic level endemism in the Western Ghats-Sri Lanka biodiversity hotspot has been typically attributed to the subcontinent's geological history of long-term isolation. Subsequent out of – and into India dispersal of species after accretion to the Eurasian mainland is therefore often seen as a biogeographic factor that 'diluted' the composition of previously isolated Indian biota. However, few molecular studies have focussed on into-India dispersal as a possible source of endemism on the subcontinent. Using c. 6000 base pairs of mitochondrial and nuclear DNA, we investigated the evolutionary history and biogeography of true toads (Bufonidae), a group that colonized the Indian Subcontinent after the Indo-Asia collision.</p> <p>Results</p> <p>Contrary to previous studies, Old World toads were recovered as a nested clade within New World Bufonidae, indicating a single colonization event. Species currently classified as <it>Ansonia </it>and <it>Pedostibes </it>were both recovered as being non-monophyletic, providing evidence for the independent origin of torrential and arboreal ecomorphs on the Indian subcontinent and in South-East Asia. Our analyses also revealed a previously unrecognized adaptive radiation of toads containing a variety of larval and adult ecomorphs. Molecular dating estimates and biogeographic analyses indicate that the early diversification of this clade happened in the Western Ghats and Sri Lanka during the Late Oligocene to Early Miocene.</p> <p>Conclusion</p> <p>Paleoclimate reconstructions have shown that the Early Neogene of India was marked by major environmental changes, with the transition from a zonal- to the current monsoon-dominated climate. After arrival in the Western Ghats-Sri Lanka hotspot, toads diversified <it>in situ</it>, with only one lineage able to successfully disperse out of these mountains. Consequently, higher taxonomic level endemism on the Indian Subcontinent is not only the result of Cretaceous isolation, but also of invasion, isolation and radiation of new elements after accretion to the Eurasian mainland.</p

    Green consumer markets in the fight against climate change

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    Climate change has become one of the greatest threats to environmental security, as attested by the growing frequency of severe flooding and storms, extreme temperatures and droughts. Accordingly, the European Union’s (EU) 6th Environment Action Programme (2010) lists tackling climate change as its first priority. A key aim of the EU has been to cut CO2 emissions, a major factor in climate change, by 8% until 2012 and 20% until 2020. The European Commission has proposed the encouragement of private consumer market for green products and services as one of several solutions to this problem. However, existing research suggests that the market share of these products has been only 3%, although 30% of individuals favour environmental and ethical goods. This article uses Public Goods Theory to explain why the contribution of the green consumer market to fighting climate change has been and possibly may remain limited without further public intervention

    Age-Related Change in the Association Choices of Two Species of Juvenile Flamingos

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    This is the final version. Available from MDPI via the DOI in this record. Data can be provided by the corresponding author upon reasonable request.Flamingos are colonial species commonly kept in zoos, well known for their bright plumage and elaborate courtship displays. This project aimed to determine the differences in flock position and association preferences of juvenile Greater Flamingos (Phoenicopterus roseus) and Caribbean Flamingos (P. ruber) housed in the same zoological collection. Little research has been conducted on the association preferences of juvenile flamingos, especially in captive flocks, and therefore this study collected data using photographs taken throughout 2014 and 2015 to further understand association patterns. Data were collected on the age category of each juvenile flamingo observed, the age of their nearest neighbour and their position within the flock, and the location within an enclosure zone at different times of the day. The results showed that Greater Flamingo juveniles mainly associated with individuals of their own age and were most likely positioned at the periphery of their flock significantly more of the time until approximately 24 months of age. Sub-adult Greater Flamingos spent significantly more time associating with adult flamingos at the centre of the flock. In contrast, data collected on Caribbean Flamingos indicated that juveniles did not segregate themselves from the adults as distinctively. Birds aged 13–24 months were observed significantly more at the centre of the flock and had more associations with adult flamingos, in a similar manner to that observed in Greater Flamingos. Due to population management needs, juvenile Caribbean Flamingos were removed from the flock at the start of 2015 and this may have influenced the association and location preferences of the remaining young flamingos. In conclusion, these results indicated that captive juvenile flamingos were often seen away from adult birds and that sub-adult flamingos returned to the heart of their natal flock to associate significantly more with other adult individuals, potentially preparing for mate selection and breeding. Captive enclosure should therefore be spacious enough to enable young flamingos to remove themselves from adult birds so that behavioural development can be unaffected by artificially high rates of aggression

    Top Quark Physics at the Tevatron

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    We review the field of top-quark physics with an emphasis on experimental techniques. The role of the top quark in the Standard Model of particle physics is summarized and the basic phenomenology of top-quark production and decay is introduced. We discuss how contributions from physics beyond the Standard Model could affect top-quark properties or event samples. The many measurements made at the Fermilab Tevatron, which test the Standard Model predictions or probe for direct evidence of new physics using the top-quark event samples, are reviewed here.Comment: 50 pages, 17 figures, 2 tables; version accepted by Review of Modern Physic

    A New Technique for Finding Needles in Haystacks: A Geometric Approach to Distinguishing Between a New Source and Random Fluctuations

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    We propose a new test statistic based on a score process for determining the statistical significance of a putative signal that may be a small perturbation to a noisy experimental background. We derive the reference distribution for this score test statistic; it has an elegant geometrical interpretation as well as broad applicability. We illustrate the technique in the context of a model problem from high-energy particle physics. Monte Carlo experimental results confirm that the score test results in a significantly improved rate of signal detection.Comment: 5 pages, 4 figure

    Historical Criminology and the Explanatory Power of the Past

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    To what extent can the past ‘explain’ the present? This deceptively simple question lies at the heart of historical criminology (research which incorporates historical primary sources while addressing present-day debates and practices in the criminal justice field). This article seeks first to categorise the ways in which criminologists have used historical data thus far, arguing that it is most commonly deployed to ‘problematize’ the contemporary rather than to ‘explain’ it. The article then interrogates the reticence of criminologists to attribute explicative power in relation to the present to historical data. Finally, it proposes the adoption of long time-frame historical research methods, outlining three advantages which would accrue from this: the identification and analysis of historical continuities; a more nuanced, shared understanding of micro/macro change over time in relation to criminal justice; and a method for identifying and analysing instances of historical recurrence, particularly in perceptions and discourses around crime and justice
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