1,423 research outputs found

    Transaction Costs in Payment of Environmental Service Contracts

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    Citation: Jeffrey M. Peterson, Craig M. Smith, John C. Leatherman, Nathan P. Hendricks, John A. Fox; Transaction Costs in Payment for Environmental Service Contracts, American Journal of Agricultural Economics, Volume 97, Issue 1, 1 January 2015, Pages 219–238, https://doi.org/10.1093/ajae/aau071Payment for environmental service contracts commonly require actions beyond adoption of a practice, such as undergoing specified enrollment procedures, granting consent to being monitored, and paying penalties for violations. These provisions are a bundle of attributes a landholder must accept with contract enrollment, leading to transaction costs in the contracting process. This article develops a principal–agent framework to study the links between these transaction costs and the well-known information asymmetries between the landholders and the government agency offering contracts. Using stated choice data collected from a sample of farmers, we estimate a mixed logit model to quantify the contribution of different contract attributes on contract willingness-to-accept (WTA). More stringent provisions in contracts were found to raise individual WTA by widely differing amounts across farmers, but the average effects imply that overall contract supply is sensitive to stringency. From a series of microsimulations based on the estimated model, we find that transaction costs create a significant drain on the cost-effectiveness of contracting from the agency’s point of view, similar in magnitude to the inefficiency created by hidden information. Although stringent contractual terms raise program expenditures, they may be justified if they raise compliance rates enough to offset the added cost. We also simulate an implicit frontier to trace out the change in compliance needed to justify a given increase in stringency. For environmental benefits in the range of previous estimates, this analysis suggests that stringent terms would need to substantially raise compliance rates to be cost effective

    Population-based detection of systolic and diastolic dysfunction with amino-terminal pro-B-type natriuretic peptide

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    Background: There is limited information regarding the clinical utility of amino-terminal pro-B-type natriuretic peptide (NT-proBNP) for the detection of left ventricular (LV) dysfunction in the community. We evaluated predictors of circulating NT-proBN

    Quality assurance of 61Cu using ICP mass spectroscopy and metal complexation

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    Introduction 61Cu (T1/2 = 3.33 hr, Eβ= 1.22 MeV, 61.4 %) is an attractive isotope for positron emission tomography (PET) radiopharmaceutical agents such as ATSM and PTSM. Various separation processes have been reported for the production of 61Cu on a medium cyclotron using 13–22 MeV protons on natural and enriched 64Zn target materials [1,2]. This work, investigates production of 61Cu using both natural and enriched 64Zn targets and its separation. Three types of resins were used to assess for their efficiency and speed to separate the desired 61Cu from the 66,67,68Ga and 64Zn and for the recycling of 64Zn target material. The effective specific activity of purified 61Cu, was determined by ICP-MS and its titration with various polyaza and polycarboxylate complexing ligands. Material and Methods 1. Production and Separation Targets were irradiated by proton beam of IBA cyclotron 18/18MeV via the 64Zn(p,α) 61Cu and natZn(p,x) 61Cu reactions using an enriched 64Zn foil(15×15×0.05mm, ~50 mg) and natural foil (diameter 25 mm, 0.05 mm,~ 60 mg). Thirty minute irradiations were conducted with incident proton energies between 11.7–12.0 MeV and beam currents of 20 and 40 µA. Irradiated Zn targets were dissolved in 8M HCl at 150 oC then evaporated to dryness. Trace water to the resultant residue (twice) and resultant solutions evaporated to dryness. The residue was re-dissolved in 2ml of 0.01M HCl before loading onto a Cu-resin column (FIG. 1) Zn and Ga isotopes were collectively eluted using 30 ml of 0.01M HCl. The Cu was then removed using 1.5 ml of 8M HCl and passed directly onto a cation exchange followed by an anion exchange column. An additional 3 ml of 8M HCl was used to rinse the cation exchange column and ensure quantitatively removal of Cu (II) ions. The Cu was finally eluted from the anion exchange column using 3 ml of 2M HCl. The Cu solution was heated up at 150 oC until evaporated to dryness and 61Cu final product dissolved in 400–800 μL of 0.01M HCl. 2. Specific activity of 61Cu The specific activity (GBq/µmol) of the purified 61Cu was determined by ICP-MS and compared with that determined using dota, nota and di-amsar complexing ligands. For each 61Cu production run aliquot of final solution (100 µL) was left to decay before dilut-ing to 10 mL with 10% HNO3. Decayed samples were sent to ChemCentre (Curtin University) for ICP-MS analysis. Each sample was analysed for Cu, Al, Ca, Co, Fe, Ga, Ni, Si, and Zn, which are known to compete with Cu2+ for ligand complexation. Effective specific activity of the 61Cu was deter-mined by titrating various known concentration of ligands with 61Cu solution. The method is detailed in the literature [3]. Briefly, varying concentrations of each ligand was prepared in 0.1M sodium acetate buffer pH 6.5 to a total volume 20 µL. Fixed concentration of diluted 61Cu (0.01M HCl) in 10 µL was added to each ligand solution. The mixtures were vortexed then left to incubate at the room temperature for 30 mins. Two uL aliquots were withdrawn (in triplicate) from each reaction mixture and spot-ted on ITLC –SA. [Mobile phase: 0.1M NaCl: 0.1M EDTA (9:1) for Cu2+ and diamsar mixtures: Rf 0.8 free Cu2+ and 0.1M sodium acetate pH 4.5: H2O: MeOH: ammonium hydroxide (20:18:2:1 v/v) for Cu2+ dota and nota mixtures: Rf >0.8 Cu-dota and Cu-nota Rf < 0.2 free Cu2+]. Complexation of the 61Cu with each ligand was complete within 30 mins at room temperature. Concentration of Cu2+ was deter-mined from the 50% labelling efficiency. Results and Conclusion 1. Production and Separation The radioisotopes production from natZn target must be minimized by the optimum proton energy to reduce a radiation dose in the final product. The excitation functions of 66,67,68Ga ,65Zn and 61Cu are shown in FIG. 2. Proton beam energy of 11.7 MeV was used for both Zn targets to minimise the production of Ga isotopes and prevent formation of 65Zn. For the enriched 64Zn target (99.30%) higher proton energy could be used for the production of 61Cu allowing for increased yields and reduce radio contaminants. Previously, we used anion and cation exchange resin as described in the literature to separate the 61Cu [1]. Unfortunately the literature method was too long (up to 3 hours) and requiring high concentration of HCl and long evaporation times compromising achievable yields [4]. Thieme S. et al., 2013 [2] reported the successful use of Cu-resin for the separation of Cu radioisotopes and it was of interest to the current work to test this material for the separation of 61Cu in our hands. A cation, anion exchange and Cu-resin were combined into closed system to separate the 61Cu within 30 mins (FIG. 1). The system is designed to contain the transfer of solutions be-tween each column using simple plunger to force solution through and between each column. This system afforded an easy, reliable and fast separation of 61Cu that could be completed within 30 min. 2. Specific activity The specific activity of 61Cu was determined using ICP-MS and by titration with three ligands is summarized in TABLE 1. The ICP-MS data show values ranging from 9.2 to 32.4 GBq/μmol for 8 production runs. Specific activity determine using nota and dota were in all cases lower than the ICP MS data indicating some interference from the other metal ion contaminates such as Fe(ii/Iii), Ni (II), Ca (II), Zn (II), Ga (III). The specific activity determine using diamsar, which is known to be highly selective for Cu(II) (and Zn(II) and Fe(III)) in the presence of alkali and alkaline earth ions gave values significantly higher effective specific activity than that obtained using ICP MS. Variations in values can be explained by presence of contaminating metal ions

    Observations and asteroseismic analysis of the rapidly pulsating hot B subdwarf PG 0911+456

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    The principal aim of this project is to determine the structural parameters of the rapidly pulsating subdwarf B star PG 0911+456 from asteroseismology. Our work forms part of an ongoing programme to constrain the internal characteristics of hot B subdwarfs with the long-term goal of differentiating between the various formation scenarios proposed for these objects. First comparisons of asteroseismic values with evolutionary theory look promising, however it is clear that more targets are needed for meaningful statistics to be derived. The observational pulsation periods of PG 0911+456 were extracted from rapid time-series photometry using standard Fourier analysis techniques. Supplemented by spectroscopic estimates of the star's mean atmospheric parameters, they were used as a basis for the "forward modelling" approach in asteroseismology. The latter culminates in the identification of one or more "optimal" models that can accurately reproduce the observed period spectrum. This naturally leads to an identification of the oscillations detected in terms of degree l and radial order k, and infers the structural parameters of the target. From the photometry it was possible to extract 7 independent pulsation periods in the 150-200 s range with amplitudes between 0.05 and 0.8 % of the star's mean brightness. An asteroseismic search of parameter space identified several models that matched the observed properties of PG 0911+456 well, one of which was isolated as the "optimal" model on the basis of spectroscopic and mode identification considerations. All the observed pulsations are identified with low-order acoustic modes with degree indices l=0,1,2 and 4, and match the computed periods with a dispersion of only ~0.26 %.Comment: accepted for publication in A&A, 14 pages, 13 figure

    Foraging Ecology of Fall-Migrating Shorebirds in the Illinois River Valley

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    Populations of many shorebird species appear to be declining in North America, and food resources at stopover habitats may limit migratory bird populations. We investigated body condition of, and foraging habitat and diet selection by 4 species of shorebirds in the central Illinois River valley during fall migrations 2007 and 2008 (Killdeer [Charadrius vociferus], Least Sandpiper [Calidris minutilla], Pectoral Sandpiper [Calidris melanotos], and Lesser Yellowlegs [Tringa flavipes]). All species except Killdeer were in good to excellent condition, based on size-corrected body mass and fat scores. Shorebird diets were dominated by invertebrate taxa from Orders Diptera and Coleoptera. Additionally, Isopoda, Hemiptera, Hirudinea, Nematoda, and Cyprinodontiformes contribution to diets varied by shorebird species and year. We evaluated diet and foraging habitat selection by comparing aggregate percent dry mass of food items in shorebird diets and core samples from foraging substrates. Invertebrate abundances at shorebird collection sites and random sites were generally similar, indicating that birds did not select foraging patches within wetlands based on invertebrate abundance. Conversely, we found considerable evidence for selection of some diet items within particular foraging sites, and consistent avoidance of Oligochaeta. We suspect the diet selectivity we observed was a function of overall invertebrate biomass (51.264.4 [SE] kg/ha; dry mass) at our study sites, which was greater than estimates reported in most other food selection studies. Diet selectivity in shorebirds may follow tenants of optimal foraging theory; that is, at low food abundances shorebirds forage opportunistically, with the likelihood of selectivity increasing as food availability increases. Nonetheless, relationships between the abundance, availability, and consumption of Oligochaetes for and by waterbirds should be the focus of future research, because estimates of foraging carrying capacity would need to be revised downward if Oligochaetes are truly avoided or unavailable for consumption

    Kepler Presearch Data Conditioning II - A Bayesian Approach to Systematic Error Correction

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    With the unprecedented photometric precision of the Kepler Spacecraft, significant systematic and stochastic errors on transit signal levels are observable in the Kepler photometric data. These errors, which include discontinuities, outliers, systematic trends and other instrumental signatures, obscure astrophysical signals. The Presearch Data Conditioning (PDC) module of the Kepler data analysis pipeline tries to remove these errors while preserving planet transits and other astrophysically interesting signals. The completely new noise and stellar variability regime observed in Kepler data poses a significant problem to standard cotrending methods such as SYSREM and TFA. Variable stars are often of particular astrophysical interest so the preservation of their signals is of significant importance to the astrophysical community. We present a Bayesian Maximum A Posteriori (MAP) approach where a subset of highly correlated and quiet stars is used to generate a cotrending basis vector set which is in turn used to establish a range of "reasonable" robust fit parameters. These robust fit parameters are then used to generate a Bayesian Prior and a Bayesian Posterior Probability Distribution Function (PDF) which when maximized finds the best fit that simultaneously removes systematic effects while reducing the signal distortion and noise injection which commonly afflicts simple least-squares (LS) fitting. A numerical and empirical approach is taken where the Bayesian Prior PDFs are generated from fits to the light curve distributions themselves.Comment: 43 pages, 21 figures, Submitted for publication in PASP. Also see companion paper "Kepler Presearch Data Conditioning I - Architecture and Algorithms for Error Correction in Kepler Light Curves" by Martin C. Stumpe, et a

    Diabetes Medication Assistance Service: The pharmacist's role in supporting patient self-management of type 2 diabetes (T2DM) in Australia

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    Objective. To evaluate the capacity and effectiveness of trained community pharmacists in delivering the Diabetes Medication Assistance Service (DMAS) via (1) number and types of self-management support interventions (SMSIs); (2) number of goals set and attained by patients and (3) patient outcomes (glycaemic control, medication adherence and satisfaction). Methods. Pharmacists (n = 109) from 90 community pharmacies in Australia were trained and credentialed to deliver the DMAS. The training focused on developing pharmacists’ knowledge and skills in supporting patients’ diabetes self-management. Results. A total of 387 patients completed the trial. The mean number of SMSIs per patient was 35 (SD ±31) and the majority (87%) had at least one documented goal that was fully or partially attained. There were significant health benefits for patients including improved glycaemic control and a reduced risk of non-adherence to medications. Over 90% of DMAS patients reported improvements in their knowledge about diabetes self-management.Conclusion. The DMAS provides self management support in the community pharmacy for people with T2DM which may result in improved clinical outcomes. Practice implication. Given appropriate training in diabetes care and behavior change strategies, community pharmacists can offer programs which provide self-management support to their patients with T2DM and improve their health outcomes

    Electrical properties of methane hydrate + sediment mixtures

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    Knowledge of the electrical properties of multicomponent systems with gas hydrate, sediments, and pore water is needed to help relate electromagnetic (EM) measurements to specific gas hydrate concentration and distribution patterns in nature. Toward this goal, we built a pressure cell capable of measuring in situ electrical properties of multicomponent systems such that the effects of individual components and mixing relations can be assessed. We first established the temperature-dependent electrical conductivity (?) of pure, single-phase methane hydrate to be ~5 orders of magnitude lower than seawater, a substantial contrast that can help differentiate hydrate deposits from significantly more conductive water-saturated sediments in EM field surveys. Here we report ? measurements of two-component systems in which methane hydrate is mixed with variable amounts of quartz sand or glass beads. Sand by itself has low ? but is found to increase the overall ? of mixtures with well-connected methane hydrate. Alternatively, the overall ? decreases when sand concentrations are high enough to cause gas hydrate to be poorly connected, indicating that hydrate grains provide the primary conduction path. Our measurements suggest that impurities from sand induce chemical interactions and/or doping effects that result in higher electrical conductivity with lower temperature dependence. These results can be used in the modeling of massive or two-phase gas-hydrate-bearing systems devoid of conductive pore water. Further experiments that include a free water phase are the necessary next steps toward developing complex models relevant to most natural systems

    The implications of the regional haze rule on renewable and wind energy development on Native American lands in the west: Working paper series--02-21

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    A study conducted at Northern Arizona University investigated the barriers and opportunities facing Native American tribes in the west when considering development of their renewable energy resources in order to reduce regional haze. This paper summarizes some of the findings of that work with special attention to wind energy. Background information is presented concerning the regional haze rule and the western regional air partnership, and some of the circumstances surrounding development of tribal energy resources. An assessment of tribal energy issues revealed that many Native American tribes are interested in developing their renewable resources. However, this development should occur within the context of maintaining and strengthening their cultural, social, economic, and political integrity. Furthermore, it is shown that Native American lands possess an abundant wind resource. A list of potential actions in which tribes may participate prior to or during development of their wind or renewable resources is provided
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