693 research outputs found

    The Rubidge Collection of fossil Karroo vertebrates

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    Main articleWherever palaeontologists interested in fossils from the strata of the Karroo system discuss the systematics and evolutionary importance of Permian and Triassic vertebrates they perforce have to consider the facts that have been revealed by studies of the hundreds of specimens forming what is known as the "Rubidge Collection".Non

    Note on the distribution of fossil Reptilia of Karroo age

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    Main articleReviews briefly the geographical and stratigraphical distribution of reptilia of Karroo age, both within and beyond the confines of the southern hemishpere. Draws attention to the need for further environmental and population studies.Non

    'Can you give it to someone who needs it more? Remunerating people who participate in research

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    In this short commentary, we reflect critically on the practice of remunerating people for their participation in qualitative research by drawing on our own ongoing research exploring ‘working mums’ experiences of mothering during economic crisis

    Exploring break-points and interaction effects among predictors of the international digital divide

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    Cataloged from PDF version of article.The deepening of the digital divide between countries has prompted international organizations and governments to work together toward reducing the problem over the next 15 years. However, such efforts will likely succeed only if they are based on a firm grasp of the divide's underlying causes. In this paper we report the results of a comprehensive analysis of the determinants of the international digital divide. Our results confirm many findings of past research, but also extend existing knowledge in important ways. By employing Multivariate Adaptive Regression Splines (MARS), we discover non-linearities and interaction effects among the predictors. We then articulate significant policy implications based upon these findings

    Model selection in High-Dimensions: A Quadratic-risk based approach

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    In this article we propose a general class of risk measures which can be used for data based evaluation of parametric models. The loss function is defined as generalized quadratic distance between the true density and the proposed model. These distances are characterized by a simple quadratic form structure that is adaptable through the choice of a nonnegative definite kernel and a bandwidth parameter. Using asymptotic results for the quadratic distances we build a quick-to-compute approximation for the risk function. Its derivation is analogous to the Akaike Information Criterion (AIC), but unlike AIC, the quadratic risk is a global comparison tool. The method does not require resampling, a great advantage when point estimators are expensive to compute. The method is illustrated using the problem of selecting the number of components in a mixture model, where it is shown that, by using an appropriate kernel, the method is computationally straightforward in arbitrarily high data dimensions. In this same context it is shown that the method has some clear advantages over AIC and BIC.Comment: Updated with reviewer suggestion

    Derek Mahon's Seascapes Mediated through Greece: Antiquity in Modernity, Nature in Abstraction.

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    The article investigates various approaches to seascape in selected poems of the contemporary Irish poet, Derek Mahon, set against the background of references to Michael Longley, Seamus Heaney or Odysseus Elytis. The sea provides a perspective that cannot be overestimated in trying to get an insight into the communication and the clash between the culture of the South and the North. The two nations have often glimpsed at their reflection in the mirror of the surrounding seas, their history and mentality determined by their geographical position and largely insular experience. Elements such as the isolation from the mainland; the perception of the sea as a personification of the force ruling over life and death, as a threat and a promise; or the focus on some characteristic natural phenomena such as light or surface dominate the seascape imagery both in Greek and Irish literature. The sea often constitutes a border of antagonistic and complementary worlds: dream and reality, light and darkness, male and female, the real world and the underworld – and the vantage point of the poet changes accordingly. Some poems under discussion also explore a series of myths linked with the sea, the best known of which, the Odyssey, has remained a frame of reference for numerous contemporary Greek and Irish poets. Elytis's Cyclades or Longley's Mayo provide us with examples of 'private homelands'. As Longley once observed, “his part of Mayo” reminds him of Ithaca (sandy and remote) and of Greece in general: “I’ve often thought that that part of Ireland . . . looks like Greece. Or Greece looks like a dust-bowl version of Ireland,” which triggers further deliberations on seascape as the common ground for the two countries. Just as Elytis's Cyclades or Longley's Mayo, Mahon’s Cyclades provide us with examples of 'private homelands'. The focus of this article is Derek Mahon’s seascapes: purely Greek (‘Aphrodite’s Pool’), Irish seen through the prism of the Greek ones (‘Achill’) and purely Irish (‘Recalling Aran’). The level of abstraction in the last category is compared with Odysseus Elytis’s imagery of the Cyclades, while the first poem demystifies a practice which I termed as ‘myth trading’, one of consumerist tourism techniques

    Flight performance of actively foraging honey bees is reduced by a common pathogen

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    ArticleSudden and severe declines in honey bee (Apis mellifera) colony health in the US and Europe have been attributed, in part, to emergent microbial pathogens, however, the mechanisms behind the impact are unclear. Using roundabout flight mills, we measured the flight distance and duration of actively foraging, healthy-looking honey bees sampled from standard colonies, before quantifying the level of infection by Nosema ceranae and Deformed Wing Virus complex (DWV) for each bee. Neither the presence nor quantity of N. ceranae at low, natural levels of infection had any effect on flight distance or duration, but presence of DWV reduced flight distance by two thirds and duration by one half. Quantity of DWV was shown to have a significant, but weakly positive relation with flight distance and duration, however, the low amount of variation that was accounted for suggests further investigation by dose-response assays is required. We conclude that widespread, naturally occurring levels of infection by DWV weaken the flight ability of honey bees and high levels of within-colony prevalence are likely to reduce efficiency and increase the cost of resource acquisition. Predictions of implications of pathogens on colony health and function should take account of sub-lethal effects on flight performance.This work was funded by the Insect Pollinators Initiative (IPI) grants BB/I000100/1, BB/I000097/1 and BB/I000097/2, C.B. Dennis British Beekeepers' Research Trust and the High Wycombe Beekeepers’ Association. The IPI is funded jointly by the BBSRC, Defra, NERC, The Scottish Government and The Wellcome Trust, under the LWEC Partnership. Rothamsted Research is a national institute of bioscience strategically funded by the BBSRC

    Leisure-Time Physical Activity and Characteristics of Social Network Support for Exercise Among Latinas

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    Purpose: To examine the association between characteristics of social support for exercise and moderate-to-vigorous leisure-time physical activity (LTPA) among Latinas. Design: This cross-sectional study used baseline data from a cluster randomized controlled trial. Setting: The study was conducted in 16 churches located in San Diego County. Participants: Participants (N = 436) were Latinas between 18 and 65 years old who did not self-report >150 minutes or did not exceed 250 minutes of moderate-to-vigorous PA per week measured by accelerometer. Measures: Latinas listed up to 6 individuals who had provided support for exercise within the past 6 months, including their gender, relationship with the respondent, types of support provided, and respondent’s satisfaction with support. Self-reported LTPA was dichotomized (none vs any). Analyses: We generated dyads between Latinas who named ≥1 supporter (n = 323) and each supporter they named (n = 569 dyads). Logistic regression analyses were conducted using generalized estimating equations to adjust for multiple observations per participant. Results: Having an exercise partner (odds ratio [OR]: 2.16; 95% confidence interval [CI]: 1.01-4.62), help with household duties (OR: 2.70; 95% CI: 1.35-3.38), being “very much” satisfied with support (OR: 2.33; 95% CI: 1.26-4.30), and naming >2 supporters (OR: 2.57; 95% CI: 1.06-6.25) was positively associated with LTPA. Conclusions: Findings suggest specific aspects of support for exercise that should be targeted in future interventions to promote LTPA

    Evaluating the integration of Blockchain Technologies in Supply Chain Management: a case study of sustainable fishing

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    As a consequence of the Global pandemic, Supply Change Management (SCM) is becoming more complex due to market uncertainty across value chains; from sourcing materials to logistics and production. With the development of contemporary technology, blockchain may allay this worry by providing the SCM industry with automated software solutions. Blockchain is an emerging technology that supports a distributed and transparent approach to transactions between various entities. Due to increased digital usage across many sectors, the technology is being adopted more commonly in real-world business applications that aim to achieve transparency and security along a distributed chain of processes. Examining how these applications are deployed, based on the respective domain creates opportunities for future research and in advancing current thought processes of supply chain practitioners. This research aims to assess the fishing industry and provide a solution to trace the complete seafood lifecycle by capturing, recording, and tracking all relevant activities and data (e.g., video, photo, documents) from "bait to plate" and provide an open and immutable history record for each transaction in the supply chain of this lifecycle. The research offers valuable insight for supply chain practitioners into how blockchain technology has the potential to disrupt existing supply chain deployments and highlights some challenges of its successful adoption. Emerging blockchain applications aim to help businesses, including supply-chain transparency for a wide range of products

    Interpreting syndepositional sediment remobilization and deformation beneath submarine gravity flows; a kinematic boundary layer approach

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    Turbidite sandstones and related deposits commonly contain deformation structures and remobilized sediment that might have resulted from post-depositional modification such as downslope creep (e.g. slumping) or density-driven loading by overlying deposits. However, we consider that deformation can occur during the passage of turbidity currents that exerted shear stress on their substrates (whether entirely pre-existing strata, sediment deposited by earlier parts of the flow itself or some combination of these). Criteria are outlined here, to avoid confusion with products of other mechanisms (e.g. slumping or later tectonics), which establish the synchronicity between the passage of overriding flows and deformation of their substrates. This underpins a new analytical framework for tracking the relationship between deformation, deposition and the transit of the causal turbidity current, through the concept of kinematic boundary layers. Case study examples are drawn from outcrop (Miocene of New Zealand, and Apennines of Italy) and subsurface examples (Britannia Sandstone, Cretaceous, UK Continental Shelf). Example structures include asymmetric flame structures, convolute lamination, some debritic units and injection complexes, together with slurry and mixed slurry facies. These structures may provide insight into the rheology and dynamics of submarine flows and their substrates, and have implications for the development of subsurface turbidite reservoirs
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