1,431 research outputs found

    Protest Adjustments in the Valuation of Watershed Restoration Using Payment Card Data

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    When using a willingness-to-pay (WTP) format in contingent valuation (CV) to value water-shed restoration, respondents may protest by questioning why they should pay to clean up a pollution problem that someone else created. Using a sample selection interval data model based on Bhat (1994) and Brox, Kumar, and Stollery (2003), we found that the decision to protest and WTP values were correlated. Protest sample selection bias resulted in a 300 percent overestimate of mean WTP per respondent. Using different ad hoc treatments of protesters, protest bias resulted in moderate effects (-10 percent to +14 percent) after controlling for sample selection bias.contingent valuation, protest bias, watershed restoration, sample selection, grouped Tobit, Resource /Energy Economics and Policy,

    TOTAL ECONOMIC VALUATION OF STREAM RESTORATION USING INTERNET AND MAIL SURVEYS

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    The economic value of restoring Deckers Creek in Monongalia and Preston Counties of West Virginia was determined from mail, internet and personal interview surveys. Multi-attribute, choice experiments were conducted and nested logit models were estimated to derive the economic values of full restoration for three attributes of this creek: aquatic life, swimming, and scenic quality. The relative economic values of attributes were: aquatic life > scenic quality ~ swimming. These economic values imply that respondents had the highest value for aquatic life when fully restoring Deckers Creek to a sustainable fishery rather than "put and take" fishery that can not sustain a fish population (defined as moderate restoration for aquatic life). The consumer surplus estimates for full restoration of all three attributes ranged between 12and12 and 16 per month per household. Potential stream users (anglers) had the largest consumer surplus gain from restoration while non-angler respondents had the lowest. When the consumer surplus estimates were aggregated up to the entire watershed population, the benefit from restoration of Deckers Creek was estimated to be about $1.9 million annually. This benefit does not account for any economic values from partial stream restoration. Based upon log likelihood tests of the nested logit models, two sub-samples of the survey population (the general population and stream users) were found to be from the same population. Thus, restoration choices by stream users may be representative of the watershed population, although the sample size of stream users was small in this study.Resource /Energy Economics and Policy,

    Bolla Bollana boulder beds:A Neoproterozoic trough mouth fan in South Australia?

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    The Bolla Bollana Formation is an exceptionally thick (ca 1500 m), rift-related sedimentary succession cropping out in the northern Flinders Ranges, South Australia, which was deposited during the Sturtian (mid Cryogenian) glaciation. Lithofacies analysis reveals three distinct facies associations which chart changing depositional styles on an ice-sourced subaqueous fan system. The diamictite facies association is dominant, and comprises both massive and stratified varieties with a range of clast compositions and textures, arranged into thick beds (1 to 20 m), representing stacked, ice-proximal glaciogenic debris-flow deposits. A channel belt facies association, most commonly consisting of normally graded conglomerates and sandstones, displays scour and fill structure of ca 10 m width and 1 to 3 m depth: these strata are interpreted as channelized turbidites. Rare mud-filled channels in this facies association bear glacially striated lonestones. Finally, a sheet heterolithics facies association contains a range of conglomerates through sandstones to silty shales arranged into clear, normally graded cycles from the lamina to bed scale. These record a variety of non-channelized turbidites, probably occupying distal and/or inter-channel locations on the subaqueous fan. Coarsening and thickening-up cycles, capped by dolomicrites or mudstones, are indicative of lobe build out and abandonment, potentially as a result of ice lobe advance and stagnation. Dropstones, recognized by downwarped and punctured laminae beneath pebbles to boulders in shale, or in delicate climbing ripple cross-laminated siltstones, are clearly indicative of ice rafting. The co-occurrence of ice-rafted debris and striated lonestones strongly supports a glaciogenic sediment source for the diamictites. Comparison to Pleistocene analogues enables an interpretation as a trough mouth fan, most probably deposited leeward of a palaeo-ice stream. Beyond emphasizing the highly dynamic nature of Sturtian ice sheets, these interpretations testify to the oldest trough mouth fan recorded to date.Daniel P. Le Heron, Marie E. Busfield, and Alan S. Collin

    Observations of Overturning in the Upper Mesosphere and Lower Thermosphere

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    A number of observations of the sodium density primarily in the mesosphere and lower thermosphere (but also of the electron density structure) have shown what appears to be overturning or convective roll cells near the transition from the mesosphere to the lower thermosphere. The cells are found in the region between 95 and 105 km and occur near the boundary between the region of lower stability in the mesosphere and the region of higher stability in the lower thermosphere. The vertical scale for the rolls is ~5–6 km, and the timescale is ~1–3 hours. The rolls occur in a region characterized by large shear in the neutral winds, but the timescales are too long to be explained by simple Kelvin-Helmholtz instability. We present observations from the University of Illinois lidar facility located at the Starfire Optical Range near Albuquerque, New Mexico, from the Arecibo Observatory in Puerto Rico, and from the Maui/MALT Lidar Facility located on Maui in Hawaii that show the overturning structure. Possible mechanisms for generating the convective rolls are discussed, including the relationship of the observed features to the characteristics expected for an inflection point instability

    Clinical characteristics of emergency department heart failure patients initially diagnosed as non-heart failure

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    BACKGROUND: Since previous studies suggest the emergency department (ED) misdiagnosis rate of heart failure is 10–20% we sought to describe the characteristics of ED patients misdiagnosed as non-decompensated heart failure in the ED. METHODS: We analyzed a prospective convenience sample of 439 patients at 4 emergency departments who presented with signs or symptoms of decompensated heart failure. Patients with a cardiology criterion standard diagnosis of decompensated heart failure and an ED diagnosis of decompensated heart failure were compared to patients with a criterion standard of decompensated heart failure but no ED diagnosis of decompensated heart failure. Two senior cardiology fellows retrospectively determined the patient's heart failure status during their acute ED presentation. The Mann-Whitney u-test for two groups, the Kruskall-Wallis test for multiple groups, or Chi-square tests, were used as appropriate. RESULTS: There were 173 (39.4%) patients with a criterion standard diagnosis of decompensated heart failure. Among those with this criterion standard diagnosis of decompensated heart failure, discordant patients without an ED diagnosis of decompensated heart failure (n = 58) were more likely to have a history of COPD (p = 0.017), less likely to have a previous history of heart failure (p = 0.014), and less likely to have an elevated b-type natriuretic peptide (BNP) level (median 518 vs 764 pg/ml; p = 0.038) than those who were given a concordant ED diagnosis of decompensated heart failure. BNP levels were higher in those with a criterion standard diagnosis of decompensated heart failure than in those without a criterion standard diagnosis (median 657 vs 62.7 pg/ml). However, 34.6% of patients with decompensated heart failure had BNP levels in the normal (<100 pg/ml; 6.1%) or indeterminate range (100–500 pg/ml; 28.5%). CONCLUSION: We found the ED diagnoses of decompensated heart failure to be discordant with the criterion standard in 14.3% of patients, the vast majority of which were due to a failure to diagnose heart failure when it was present. Patients with a previous history of COPD, without a previous history of heart failure and with lower BNP levels were more likely to have an ED misdiagnosis of non-decompensated heart failure. Readily available, accurate, objective ED tests are needed to improve the early diagnosis of decompensated heart failure in ED patients

    Metallogenic Setting and Temporal Evolution of Porphyry Cu-Mo Mineralization and Alteration in the Delamerian Orogen, South Australia: Insights From Zircon U-Pb, Molybdenite Re-Os, and In Situ White Mica Rb-Sr Geochronology

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    Paleozoic porphyry-style hydrothermal alteration and mineralization has previously been recognized within the Delamerian orogen, South Australia, where porphyry prospects include Anabama Hill, Netley Hill, and Bendigo. However, limited exploration due in part to thick postmineralization cover hinders the understanding of the temporal context, metallogenic setting, and mineral potential of the porphyry systems along the Proterozoic continental margin of Australia. In this study, we have characterized the hydrothermal alteration and mineralization of these porphyry occurrences. Zircon U-Pb, molybdenite Re-Os, and white mica Rb-Sr ages have been determined to constrain the timing for emplacement of magmatic intrusions, precipitation of metal-bearing sulfides, and duration of hydrothermal alteration in the Delamerian orogenic belt. Zircon U-Pb laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analyses of nine granitoids reveal that the intrusive rocks were emplaced mostly between 485 and 465 Ma, whereas three intrusions at Bendigo have zircon U-Pb ages of 490 to 480 Ma. Molybdenite isotope dilution-negative thermal ion mass spectrometry (ID-NTIMS) Re-Os dating of the four prospects identifies two porphyry Cu-Mo mineralization events at 480 and 470 to 460 Ma, respectively. Nineteen white mica Rb-Sr LA-ICP-MS/MS (tandem mass spectrometers) analyses return an age range between 455 and 435 Ma for phyllic alteration at the Anabama Hill and Netley Hill prospects, whereas intense white mica-quartz-pyrite alteration at Bendigo prospect appears to have developed between 470 and 460 Ma. These geochronologic results indicate that the Delamerian porphyry systems postdated subduction-related magmatism in the region (514–490 Ma) but instead formed within an inverted back-arc regime, where mineralized magmas and fluids ascended along favorable lithospheric-scale structures, probably due to asthenospheric upwelling triggered by mafic delamination. Porphyritic stocks, dikes, and aplites with ages of 470 to 460 Ma are the most likely hosts to porphyry-style mineralization in the Delamerian orogen that appears to have formed simultaneously with the oldest known porphyry systems in the intraoceanic Macquarie arc (e.g., Marsden, E43, and Milly Milly; 467–455 Ma). These results emphasize the significance and potential of Early-Middle Ordovician intrusive systems to host such a type of magmatic-hydrothermal mineralization in the Delamerian orogen

    Future Asymptotic Behaviour of Tilted Bianchi models of type IV and VIIh

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    Using dynamical systems theory and a detailed numerical analysis, the late-time behaviour of tilting perfect fluid Bianchi models of types IV and VIIh_h are investigated. In particular, vacuum plane-wave spacetimes are studied and the important result that the only future attracting equilibrium points for non-inflationary fluids are the plane-wave solutions in Bianchi type VIIh_h models is discussed. A tiny region of parameter space (the loophole) in the Bianchi type IV model is shown to contain a closed orbit which is found to act as an attractor (the Mussel attractor). From an extensive numerical analysis it is found that at late times the normalised energy-density tends to zero and the normalised variables 'freeze' into their asymptotic values. A detailed numerical analysis of the type VIIh_h models then shows that there is an open set of parameter space in which solution curves approach a compact surface that is topologically a torus.Comment: 30 pages, many postscript figure

    Kinematic constraints on the Rodinia to Gondwana transition

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    Earth's plate tectonic history during the breakup of the supercontinent Pangea is well constrained from the seafloor spreading record, but evolving plate configurations during older supercontinent cycles are much less well understood. A relative paucity of available palaeomagnetic and geological data for deep time reconstructions necessitates innovative approaches to help discriminate between competing plate configurations. More difficult is tracing the journeys of individual continents during the amalgamation and breakup of supercontinents. Typically, deep-time reconstructions are built using absolute motions defined by palaeomagnetic data, and do not consider the kinematics of relative motions between plates, even for occasions where they are thought to be ‘plate-pairs’, either rifting apart leading to the formation of conjugate passive margins separated by a new ocean basin, or brought together by collision and orogenesis. Here, we use open-source software tools (GPlates/pyGPlates) to assess quantitative plate kinematics inherent within alternative reconstructions, such as rates of relative plate motion. We analyse the Rodinia-Gondwana transition during the Neoproterozoic, investigating the proposed Australia-Laurentia configurations during Rodinia, and the motion of India colliding with Gondwana. We find that earlier rifting times provide more optimal kinematic results. The AUSWUS and AUSMEX configurations with rifting at 800 Ma are the most kinematically supported configurations for Australia and Laurentia (average rates of 57 and 64 mm/a respectively), and angular rotation of ∼1.4°/Ma, compared to a SWEAT configuration (average spreading rate ∼76 mm/a) and Missing-Link configuration (∼90 mm/a). Later rifting, at, or after, 725 Ma necessitates unreasonably high spreading rates of >130 mm/a for AUSWUS and AUSMEX and ∼150 mm/a for SWEAT and Missing-Link. Using motion paths and convergence rates, we create a kinematically reasonable (convergence below 70 mm/a) tectonic model that is built upon a front-on collision of India with Gondwana, while also incorporating sinistral strike-slip motion against Australia and East Antarctica. We use this simple tectonic model to refine a global model for the breakup of western Rodinia and the transition to eastern Gondwana. © 2017 Elsevier B.V.This manuscript is a contribution to IGCP projects 628 (Gondwana Map) and 648 (Supercontinent Cycles and Global Geodynamics). This research was supported by the Science Industry Endowment Fund (RP 04-174) Big Data Knowledge Discovery Project, Australian Research Council grant DP130101946 (RDM) and the AuScope NCRIS project. ASM is supported by a CSIRO-Data61 Postgraduate Scholarship. ASC's contribution forms TRaX Record #379 and was funded by an Australian Research Council Future Fellowship FT120100340

    Kinematic constraints on the Rodinia to Gondwana transition

    Get PDF
    Earth's plate tectonic history during the breakup of the supercontinent Pangea is well constrained from the seafloor spreading record, but evolving plate configurations during older supercontinent cycles are much less well understood. A relative paucity of available palaeomagnetic and geological data for deep time reconstructions necessitates innovative approaches to help discriminate between competing plate configurations. More difficult is tracing the journeys of individual continents during the amalgamation and breakup of supercontinents. Typically, deep-time reconstructions are built using absolute motions defined by palaeomagnetic data, and do not consider the kinematics of relative motions between plates, even for occasions where they are thought to be ‘plate-pairs’, either rifting apart leading to the formation of conjugate passive margins separated by a new ocean basin, or brought together by collision and orogenesis. Here, we use open-source software tools (GPlates/pyGPlates) to assess quantitative plate kinematics inherent within alternative reconstructions, such as rates of relative plate motion. We analyse the Rodinia-Gondwana transition during the Neoproterozoic, investigating the proposed Australia-Laurentia configurations during Rodinia, and the motion of India colliding with Gondwana. We find that earlier rifting times provide more optimal kinematic results. The AUSWUS and AUSMEX configurations with rifting at 800 Ma are the most kinematically supported configurations for Australia and Laurentia (average rates of 57 and 64 mm/a respectively), and angular rotation of ∼1.4°/Ma, compared to a SWEAT configuration (average spreading rate ∼76 mm/a) and Missing-Link configuration (∼90 mm/a). Later rifting, at, or after, 725 Ma necessitates unreasonably high spreading rates of >130 mm/a for AUSWUS and AUSMEX and ∼150 mm/a for SWEAT and Missing-Link. Using motion paths and convergence rates, we create a kinematically reasonable (convergence below 70 mm/a) tectonic model that is built upon a front-on collision of India with Gondwana, while also incorporating sinistral strike-slip motion against Australia and East Antarctica. We use this simple tectonic model to refine a global model for the breakup of western Rodinia and the transition to eastern Gondwana. © 2017 Elsevier B.V.This manuscript is a contribution to IGCP projects 628 (Gondwana Map) and 648 (Supercontinent Cycles and Global Geodynamics). This research was supported by the Science Industry Endowment Fund (RP 04-174) Big Data Knowledge Discovery Project, Australian Research Council grant DP130101946 (RDM) and the AuScope NCRIS project. ASM is supported by a CSIRO-Data61 Postgraduate Scholarship. ASC's contribution forms TRaX Record #379 and was funded by an Australian Research Council Future Fellowship FT120100340
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