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Träfflista för sökning "WFRF:(Lehner B) srt2:(2015-2019)"

Sökning: WFRF:(Lehner B) > (2015-2019)

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1.
  • Bouyoucef, S E, et al. (författare)
  • Poster Session 2 : Monday 4 May 2015, 08
  • 2015
  • Ingår i: European Heart Journal Cardiovascular Imaging. - : Oxford University Press (OUP). - 2047-2404 .- 2047-2412. ; 16 Suppl 1
  • Tidskriftsartikel (refereegranskat)
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2.
  • Smerdon, J. E., et al. (författare)
  • Comparing proxy and model estimates of hydroclimate variability and change over the Common Era
  • 2017
  • Ingår i: Climate of the Past. - : Copernicus GmbH. - 1814-9324 .- 1814-9332. ; 13:12, s. 1851-1900
  • Tidskriftsartikel (refereegranskat)abstract
    • Water availability is fundamental to societies and ecosystems, but our understanding of variations in hydroclimate (including extreme events, flooding, and decadal periods of drought) is limited because of a paucity of modern instrumental observations that are distributed unevenly across the globe and only span parts of the 20th and 21st centuries. Such data coverage is insufficient for characterizing hydroclimate and its associated dynamics because of its multidecadal to centennial variability and highly regionalized spatial signature. High-resolution (seasonal to decadal) hydroclimatic proxies that span all or parts of the Common Era (CE) and paleoclimate simulations from climate models are therefore important tools for augmenting our understanding of hydroclimate variability. In particular, the comparison of the two sources of information is critical for addressing the uncertainties and limitations of both while enriching each of their interpretations. We review the principal proxy data available for hydroclimatic reconstructions over the CE and highlight the contemporary understanding of how these proxies are interpreted as hydroclimate indicators. We also review the available last-millennium simulations from fully coupled climate models and discuss several outstanding challenges associated with simulating hydroclimate variability and change over the CE. A specific review of simulated hydroclimatic changes forced by volcanic events is provided, as is a discussion of expected improvements in estimated radiative forcings, models, and their implementation in the future. Our review of hydroclimatic proxies and last-millennium model simulations is used as the basis for articulating a variety of considerations and best practices for how to perform proxy-model comparisons of CE hydroclimate. This discussion provides a framework for how best to evaluate hydroclimate variability and its associated dynamics using these comparisons and how they can better inform interpretations of both proxy data and model simulations. We subsequently explore means of using proxy-model comparisons to better constrain and characterize future hydroclimate risks. This is explored specifically in the context of several examples that demonstrate how proxy-model comparisons can be used to quantitatively constrain future hydroclimatic risks as estimated from climate model projections.
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3.
  • Grill, G., et al. (författare)
  • Mapping the world's free-flowing rivers
  • 2019
  • Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 569:7755, s. 215-221
  • Tidskriftsartikel (refereegranskat)abstract
    • Free-flowing rivers (FFRs) support diverse, complex and dynamic ecosystems globally, providing important societal and economic services. Infrastructure development threatens the ecosystem processes, biodiversity and services that these rivers support. Here we assess the connectivity status of 12 million kilometres of rivers globally and identify those that remain free-flowing in their entire length. Only 37 per cent of rivers longer than 1,000 kilometres remain free-flowing over their entire length and 23 per cent flow uninterrupted to the ocean. Very long FFRs are largely restricted to remote regions of the Arctic and of the Amazon and Congo basins. In densely populated areas only few very long rivers remain free-flowing, such as the Irrawaddy and Salween. Dams and reservoirs and their up- and downstream propagation of fragmentation and flow regulation are the leading contributors to the loss of river connectivity. By applying a new method to quantify riverine connectivity and map FFRs, we provide a foundation for concerted global and national strategies to maintain or restore them.
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4.
  • Kraemer, B. K., et al. (författare)
  • Efficacy of Prolonged- and Immediate-release Tacrolimus in Kidney Transplantation : A Pooled Analysis of Two Large, Randomized, Controlled Trials
  • 2017
  • Ingår i: Transplantation Proceedings. - : Elsevier BV. - 0041-1345 .- 1873-2623. ; 49:9, s. 2040-2049
  • Tidskriftsartikel (refereegranskat)abstract
    • Background. Two large, prospective studies (12-03; OSAKA) compared the efficacy and tolerability of prolonged-release versus immediate-release tacrolimus in kidney transplant patients also receiving mycophenolate mofetil and low-dose corticosteroids (without induction therapy). Methods. Data were combined into one database to compare results over 24 weeks using 3 alternative endpoints: biopsy-confirmed acute rejection (BCAR); the Food and Drug Administration composite endpoint (graft loss, SCAR, and loss to follow-up), and the European Medicines Agency composite endpoint (graft loss, BCAR, and graft dysfunction). The 95% confidence intervals were calculated (10% noninferiority margin). Results. Overall, 633 patients received prolonged-release tacrolimus (12-03, n = 331; OSAKA, n = 302) and 645 received immediate-release tacrolimus (n = 336; n = 309). Baseline characteristics were comparable. Proportionately more patients receiving prolonged-release tacrolimus had trough levels of 5-15 ng/mL on day 1 (60.8%) and 2 (56.6%) versus immediate-release tacrolimus (42.5% and 43.9%, respectively, both P < .001). Efficacy of prolonged-release and immediate-release tacrolimus were similar as assessed by BCAR (13.9% vs 14.1%, respectively), European Medicines Agency composite endpoint (40.3% vs 38.3%) and US Food and Drug Administration composite endpoint (21.5% vs 19.8%). Conclusions. Novel efficacy endpoints as required by the European Medicines Agency and US Food and Drug Administration demonstrate noninferiority of prolonged-release versus immediate-release tacrolimus. Significantly more patients treated with prolonged release tacrolimus versus immediate-release tacrolimus achieved trough levels of 5 to 15 ng/mL early after transplantation.
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6.
  • Lauerwald, R., et al. (författare)
  • Natural lakes are a minor global source of N2O to the atmosphere
  • 2019
  • Ingår i: Global Biogeochemical Cycles. - : Wiley-Blackwell. - 0886-6236 .- 1944-9224. ; 33:12, s. 1564-1581
  • Tidskriftsartikel (refereegranskat)abstract
    • Natural lakes and reservoirs are important, yet not well constrained sources of greenhouse gasses to the atmosphere. In particular for N2O emissions, a huge variability is observed in the few, observation‐driven flux estimates that have been published so far. Recently, a process‐based, spatially explicit model has been used to estimate global N2O emissions from more than 6,000 reservoirs based on nitrogen (N) and phosphorous inflows and water residence time. Here, we extend the model to a dataset of 1.4 million standing water bodies comprising natural lakes and reservoirs. For validation, we normalized the simulated N2O emissions by the surface area of each water body and compared them against regional averages of N2O emission rates taken from the literature or estimated based on observed N2O concentrations. We estimate that natural lakes and reservoirs together emit 4.5±2.9 Gmol N2O‐N yr‐1 globally. Our global scale estimate falls in the far lower end of existing, observation‐driven estimates. Natural lakes contribute only about half of this flux, although they contribute 91% of the total surface area of standing water bodies. Hence, the mean N2O emission rates per surface area are substantially lower for natural lakes than for reservoirs with 0.8±0.5 mmol N m‐2yr‐1 vs. 9.6±6.0 mmol N m‐2yr‐1, respectively. This finding can be explained by on average lower external N inputs to natural lakes. We conclude that upscaling based estimates, which do not distinguish natural lakes from reservoirs, are prone to important biases.
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7.
  • Lehner, B.A.E., et al. (författare)
  • End-to-end mission design for microbial ISRU activities as preparation for a moon village
  • 2019
  • Ingår i: Acta Astronautica. - : Elsevier. - 0094-5765 .- 1879-2030. ; 162, s. 216-226
  • Tidskriftsartikel (refereegranskat)abstract
    • In situ resource utilization (ISRU) increasingly features as an element of human long-term exploration and settlement missions to the lunar surface. In this study, all requirements to test a novel, biological approach for ISRU are validated, and an end-to-end mission architecture is proposed. The general mission consists of a lander with a fully autonomous bioreactor able to process lunar regolith and extract elemental iron. The elemental iron could either be stored or directly utilized to generate iron wires or construction material. To maximize the success rate of this mission, potential landing sites for future missions are studied, and technical details (thermal radiation, shielding, power-supply) are analyzed. The final section will assess the potential mission architecture (orbit, rocket, lander, timeframe). This design might not only be one step further towards an international “Moon Village”, but may also enable similar missions to ultimately colonize Mars and further explore our solar system.
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