78 research outputs found

    Evaluation of Legacy Forest Harvesting Impacts on Dominant Stream Water Sources and Implications for Water Quality Using End Member Mixing Analysis

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    Forests are critical water supply regions that are increasingly threatened by natural and anthropogenic disturbance. Evaluation of runoff-generating processes within harvested and undisturbed headwater catchments provides insight into disturbance impacts on water quality and drinking water treatability. In this study, an extensive hydrologic dataset collected at the experimental Turkey Lakes Watershed (TLW) located on the Canadian Shield was used to quantify sources of stormflow in legacy clear-cut (24-years post harvesting) and forested (control) headwater catchments using an end member mixing analysis (EMMA) model. Stream water, groundwater, soil water, and throughfall water quality were evaluated during spring snowmelt, stormflow, and fall wet-up. Groundwater chemistry was similar to stream water chemistry in both catchments, suggesting that groundwater is a major contributor to stream flow. The water chemistry in small wetlands within the study catchments was comparable to stream water chemistry, suggesting that wetlands are also important contributors to stream flow. Differences in wetland position between the legacy clear-cut and control catchments appeared to have a greater influence on source contributions than legacy harvesting. Results from this study provide insight into runoff-generation processes that reflect event/seasonal flow dynamics and the impacts on water quality

    Development of a population-based microsimulation model of osteoarthritis in Canada

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    OBJECTIVES: The purpose of the study was to develop a population-based simulation model of osteoarthritis (OA) in Canada that can be used to quantify the future health and economic burden of OA under a range of scenarios for changes in the OA risk factors and treatments. In this article we describe the overall structure of the model, sources of data, derivation of key input parameters for the epidemiological component of the model, and preliminary validation studies. DESIGN: We used the Population Health Model (POHEM) platform to develop a stochastic continuous-time microsimulation model of physician-diagnosed OA. Incidence rates were calibrated to agree with administrative data for the province of British Columbia, Canada. The effect of obesity on OA incidence and the impact of OA on health-related quality of life (HRQL) were modeled using Canadian national surveys. RESULTS: Incidence rates of OA in the model increase approximately linearly with age in both sexes between the ages of 50 and 80 and plateau in the very old. In those aged 50+, the rates are substantially higher in women. At baseline, the prevalence of OA is 11.5%, 13.6% in women and 9.3% in men. The OA hazard ratios for obesity are 2.0 in women and 1.7 in men. The effect of OA diagnosis on HRQL, as measured by the Health Utilities Index Mark 3 (HUI3), is to reduce it by 0.10 in women and 0.14 in men. CONCLUSIONS: We describe the development of the first population-based microsimulation model of OA. Strengths of this model include the use of large population databases to derive the key parameters and the application of modern microsimulation technology. Limitations of the model reflect the limitations of administrative and survey data and gaps in the epidemiological and HRQL literature

    Dark Matter Search Results from the PICO-2L C3F8 Bubble Chamber

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    New data are reported from the operation of a 2 liter C3F8 bubble chamber in the SNOLAB underground laboratory, with a total exposure of 211.5 kg days at four different energy thresholds below 10 keV. These data show that C3F8 provides excellent electron-recoil and alpha rejection capabilities at very low thresholds. The chamber exhibits an electron-recoil sensitivity of 98.2%. These data also include the first observation of a dependence of acoustic signal on alpha energy. Twelve single nuclear recoil event candidates were observed during the run. The candidate events exhibit timing characteristics that are not consistent with the hypothesis of a uniform time distribution, and no evidence for a dark matter signal is claimed. These data provide the most sensitive direct detection constraints on WIMP-proton spin-dependent scattering to date, with significant sensitivity at low WIMP masses for spin-independent WIMP-nucleon scattering.The PICO Collaboration would like to thank SNOLAB and its staff for providing an exceptional underground laboratory space and invaluable technical support. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under award DE-SC-0012161. Fermi National Accelerator Laboratory is operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359. Part of the research described in this paper was conducted under the Ultra Sensitive Nuclear Measurements Initiative at Pacific Northwest National Laboratory, a multiprogram national laboratory operated by Battelle for the U.S. Department of Energy. We acknowledge the National Science Foundation for their support including Grants No. PHY-1242637, No. PHY-0919526, and No. PHY-1205987. We acknowledge the support of the National Sciences and Engineering Research Council of Canada (NSERC) and the Canada Foundation for Innovation (CFI). We also acknowledge support from the Kavli Institute for Cosmological Physics at the University of Chicago. We acknowledge the financial support of the Spanish Ministerio de Economia y Competitividad, Consolider MultiDark CSD2009-00064 Grant. We acknowledge support from the Department of Atomic Energy (DAE), Government of India, under the Center for AstroParticle Physics II project (CAPP-II) at Saha Insititute of Nuclear Physics (SINP), Kolkata. We acknowledge the Czech Ministry of Education, Youth and Sports, Grant No. LM2011027. We acknowledge technical assistance from Fermilab's Computing, Particle Physics, and Accelerator Divisions, and from A. Behnke at IUSB.Amole, C.; Ardid Ramírez, M.; Asner, DM.; Baxter, D.; Behnke, E.; Bhattacharjee, P.; Borsodi, H.... (2015). Dark Matter Search Results from the PICO-2L C3F8 Bubble Chamber. Physical Review Letters. 114(2313):1-6. https://doi.org/10.1103/PhysRevLett.114.231302S161142313Komatsu, E., Dunkley, J., Nolta, M. R., Bennett, C. L., Gold, B., Hinshaw, G., … Wright, E. L. (2009). FIVE-YEARWILKINSON MICROWAVE ANISOTROPY PROBEOBSERVATIONS: COSMOLOGICAL INTERPRETATION. The Astrophysical Journal Supplement Series, 180(2), 330-376. doi:10.1088/0067-0049/180/2/330Jungman, G., Kamionkowski, M., & Griest, K. (1996). Supersymmetric dark matter. Physics Reports, 267(5-6), 195-373. doi:10.1016/0370-1573(95)00058-5Bertone, G., Hooper, D., & Silk, J. (2005). Particle dark matter: evidence, candidates and constraints. Physics Reports, 405(5-6), 279-390. doi:10.1016/j.physrep.2004.08.031Feng, J. L. (2010). Dark Matter Candidates from Particle Physics and Methods of Detection. 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    Improved dark matter search results from PICO-2L Run 2

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    New data are reported from a second run of the 2-liter PICO-2L C3F8 bubble chamber with a total exposure of 129 kg-days at a thermodynamic threshold energy of 3.3 keV. These data show that measures taken to control particulate contamination in the superheated fluid resulted in the absence of the anomalous background events observed in the first run of this bubble chamber. One single nuclear-recoil event was observed in the data, consistent both with the predicted background rate from neutrons and with the observed rate of unambiguous multiple-bubble neutron scattering events. The chamber exhibits the same excellent electron-recoil and alpha decay rejection as was previously reported. These data provide the most stringent direct detection constraints on weakly interacting massive particle (WIMP)-proton spin-dependent scattering to date for WIMP masses < 50 GeV/c(2).The PICO Collaboration thanks SNOLAB for their exceptional laboratory space and technical support. We also thank Fermi National Accelerator Laboratory (Contract No. DE-AC02-07CH11359) and Pacific Northwest National Laboratory for their support. This work is supported by the National Sciences and Engineering Research Council of Canada (NSERC), the Canada Foundation for Innovation (CFI), the National Science Foundation (NSF) under the Grants No. PHY-1242637, No. PHY-0919526, No. PHY-1205987, and No. PHY-1506377 and by the U.S. Department of Energy under Award No. DE-SC-0012161. We also acknowledge the support of Department of Atomic Energy (DAE), Government of India, under the Center of AstroParticle Physics II project (CAPP-II) at Saha Institute of Physics (SINP); the Czech Ministry of Education, Youth and Sports (Grant No. LM2011027); the Spanish Ministerio de Economia y Competitividad, Consolider MultiDark (Grant No. CSD2009-00064) and DGAPA-UNAM through grant PAPIIT No. IA100316.Amole, C.; Ardid Ramírez, M.; Arnquist, I.; Asner, DM.; Baxter, D.; Behnke, E.; Bhattacharjee, P.... (2016). Improved dark matter search results from PICO-2L Run 2. Physical Review D. 93(6):1-5. https://doi.org/10.1103/PhysRevD.93.061101S1593

    Field characterisation of two field-scale waste rock piles

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