1,158 research outputs found

    A multiple profile approach to the palynological reconstruction of Norse landscapes in Greenland's Eastern Settlement

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    Acknowledgments The Leverhulme Trust is thanked for financial support. Gordon Cook provided radiocarbon dates. Thanks are also due to Andy McMullen for botanical identifications and assistance in the field, and to Sikuu Motzfeld for hospitality during fieldwork. We are also grateful to Emilie Gauthier, Mike Kaplan, Pete Langdon and Alan Gillespie for their comments.Peer reviewedPostprin

    Competing hypotheses, ordination and pollen preservation : landscape impacts of Norse landnám in southern Greenland

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    We thank the Leverhulme Trust for financial support, and Gordon Cook and staff at SUERC for the provision of radiocarbon dates. We are grateful to two anonymous reviewers and Shinya Sugita for valuable comments which improved the manuscript.Peer reviewedPostprin

    The biogeographical status of Alnus crispa (Ait.) Pursch in sub-Arctic southern Greenland : Do pollen records indicate local populations during the past 1500 years?

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    The Leverhulme Trust is thanked for financial support. We also thank the referees for their constructive comments that helped to improve the paper.Peer reviewedPostprin

    Stable carbon, nitrogen and sulphur isotope analysis of permafrost preserved human hair from rescue excavations (2009, 2010) at the precontact site of Nunalleq, Alaska

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    Acknowledgments This work was funded by an Arts and Humanities Research Council (AH/K006029/1) grant awarded to Rick Knecht, Kate Britton and Charlotta Hillerdal (Aberdeen); an AHRC-LabEx award (AH/N504543/1) to KB, RK, Keith Dobney (Liverpool) and Isabelle Sidéra (Nanterre); the Carnegie Trust to the Universities of Scotland (travel grant to KB); and the Max Planck Institute for Evolutionary Anthropology. The onsite collection of samples was carried out by staff and students from the University of Aberdeen, volunteer excavators and the residents of Quinhagak. We had logistical and planning support for fieldwork by the Qanirtuuq Incorporated, Quinhagak, Alaska, and the people of Quinhagak, who we also thank for sampling permissions. Special thanks to Warren Jones and Qanirtuuq Incorporated (especially Michael Smith and Lynn Church), and to all Nunalleq project team members, in Aberdeen and at other institutions, particularly Charlotta Hillerdal and Edouard Masson-Maclean (Aberdeen) for comments on earlier versions of this manuscript, and also to Véronique Forbes, Ana Jorge, Carly Ameen and Ciara Mannion (Aberdeen) for their inputs. Thanks also to Michelle Alexander (York). Finally, thank you to Ian Scharlotta (Alberta) for inviting us to contribute to this special issue, to the Editor, and to three anonymous reviewers, whose suggestions and recommended changes to an earlier version of this manuscript greatly improved the paper.Peer reviewedPublisher PD

    Inference of Temporally Varying Bayesian Networks

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    When analysing gene expression time series data an often overlooked but crucial aspect of the model is that the regulatory network structure may change over time. Whilst some approaches have addressed this problem previously in the literature, many are not well suited to the sequential nature of the data. Here we present a method that allows us to infer regulatory network structures that may vary between time points, utilising a set of hidden states that describe the network structure at a given time point. To model the distribution of the hidden states we have applied the Hierarchical Dirichlet Process Hideen Markov Model, a nonparametric extension of the traditional Hidden Markov Model, that does not require us to fix the number of hidden states in advance. We apply our method to exisiting microarray expression data as well as demonstrating is efficacy on simulated test data

    The impact of introducing patient co-payments in Germany on the use of IVF and ICSI:a price-elasticity of demand assessment

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    BACKGROUND: Authorities concerned by rising healthcare costs have a tendency to target reproductive treatments because of the perception that infertility is a low priority. In 2004 German health authorities introduced a 50% co-payment for patients, in an effort to save cost. We explored the impact of this pricing policy on the utilization of reproductive treatments in Germany. METHODS: Using aggregated annual in-vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) cycle data in Germany, we evaluated the relationship between changes in the number of cycles in relation to changes in costs faced by consumers following the introduction of a patient co-payment from 'no fees' to (sic)1500-2000 by estimating the short-run price-elasticity of demand. The impact of introducing patient co-payments for IVF/ICSI on the likelihood of switching to other low-cost fertility treatments was evaluated using the cross-price elasticity methodology. RESULTS: The reduction in demand for IVF and ICSI cycles in the year following the introduction of patient co-payments resulted in elasticities of -0.41 and -0.34, respectively. The price-elasticity for the combined reduction of IVF/ICSI in relation to the co-payment was estimated to be -0.36. The cross-price elasticity for clomifene was close to zero (-0.01) suggesting that demand for these interventions are independent of each other and no substitution occurred. CONCLUSIONS: We report price elasticities for IVF and ICSI of -0.41 and -0.34 after introducing a (sic)1500-2000 co-payment. These findings likely represent short-run elasticities that are likely to vary over time as factors that influence the supply and demand for fertility treatments change

    The application of graph theory and percolation analysis for assessing change in the spatial configuration of pond networks

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    Pond networks support high levels of biodiversity when compared to other freshwater ecosystems such as rivers, lakes and streams. The persistence of species in these small, sometimes ephemeral, aquatic habitats depends on the dispersal of individuals among ponds in the landscape. However, the number of ponds across the landscape is at a historical low as urbanisation and intensified agricultural practices have led to a substantial loss of ponds (nodes in the pond network) over more than a century. Here, we examine the extent and drivers of pond loss in a heavily urbanised landscape (Birmingham, UK) over 105 years and determine how pond loss influences key structural properties of the pond network using graph theoretic approaches. Specifically, we calculated minimum spanning trees (MST) and performed percolation analyses to determine changes in both the spatial configuration and resilience of the pond network through time. Pond numbers declined by 82% between ca1904 and 2009, such that pond density decreased from 7.1 km-2 to 1.3 km-2. The MST analyses revealed increased distance between ponds in the network (i.e. edge length increased) by up to 49% over the 105-year period, indicating that ponds in the modern landscape (2009) were considerably more isolated, with fewer neighbours. This study demonstrates that graph theory has an excellent potential to inform the management of pond networks in order to support ecological communities that are less vulnerable to environmental change

    Dating and Digging Stratified Archaeology in Circumpolar North America : A View from Nunalleq, Southwestern Alaska

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    The results presented in this paper were funded by a NERC Radiocarbon Facility grant (NRCF 1917.0415), while the wider project is funded by the Arts and Humanities Research Council (AH/K006029/1). The authors wish to thank all the members of the excavation crew from the 2014 field season for their hard work in the challenging weather conditions of southwest Alaska – without their attention to detail this study would not have been possible. Additional thanks are also due to Qanirtuuq Incorporated for logistical support and warm hospitality in Quinhagak. We also wish to thank Kevin Edwards and Kate Britton, who read an earlier draft of this paper, and three anonymous reviewers for highly constructive criticism that helped us to improve the final manuscript.Peer reviewedPublisher PD
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