3,634 research outputs found

    INCREASES IN COSTS AND RETURNS DUE TO INTENSIFYING RANGE FORAGE PRODUCTION SURVEYS: AN INFORMATION ECONOMIC ANALYSIS

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    The U.S. Congress and courts have directed federal natural resource agencies to use better information for management decisions than they have used in the past. It is also important for these agencies to improve the efficiency of resource use where possible. This information economics study estimates increased costs and revenues which can be directly imputed to improving the accuracy of range forage production surveys. It suggests that a high level of survey accuracy may often be justifiable.Crop Production/Industries, Research Methods/ Statistical Methods,

    Strong Pinning Enhancement in MgB2 Using Very Small Dy2O3 Additions

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    0.5 to 5.0 wt.% Dy2O3 was in-situ reacted with Mg + B to form pinned MgB2. While Tc remained largely unchanged, Jc was strongly enhanced. The best sample (only 0.5 wt.% Dy2O3) had a Jc of 6.5 x 10^5 A/cm^2 at 6K, 1T and 3.5 x 10^5 A/cm^2 at 20K, 1T, around a factor of 4 higher compared to the pure sample, and equivalent to hot-pressed or nano-Si added MgB2 at below 1T. Even distributions of nano-scale precipitates of DyB4 and MgO were observed within the grains. The room temperature resistivity decreased with Dy2O3 indicative of improved grain connectivity.Comment: 13 pages, 4 figures and 1 tabl

    Improved Current Densities in MgB2 By Liquid-Assisted Sintering

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    Polycrystalline MgB2 samples with GaN additions were prepared by reaction of Mg, B, and GaN powders. The presence of Ga leads to a low melting eutectic phase which allowed liquid phase sintering and produces plate-like grains. For low-level GaN additions (5% at. % or less), the critical transition temperature, Tc, remained unchanged and in 1T magnetic field, the critical current density, Jc was enhanced by a factor of 2 and 10, for temperatures of \~5K and 20K, respectively. The values obtained are approaching those of hot isostatically pressed samples.Comment: 12 pages, 1 table, 4 figures, accepted in Applied Physics Letter

    Frequency-selective single photon detection using a double quantum dot

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    We use a double quantum dot as a frequency-tunable on-chip microwave detector to investigate the radiation from electron shot-noise in a near-by quantum point contact. The device is realized by monitoring the inelastic tunneling of electrons between the quantum dots due to photon absorption. The frequency of the absorbed radiation is set by the energy separation between the dots, which is easily tuned with gate voltages. Using time-resolved charge detection techniques, we can directly relate the detection of a tunneling electron to the absorption of a single photon

    A randomized controlled trial to evaluate an educational strategy involving community health volunteers in improving self-care in patients with chronic heart failure: Rationale, design and methodology

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    © 2014, Siabani et al.; licensee Springer. Background: Chronic heart failure (CHF) is an increasingly important health problem worldwide. Effective self-care can improve the outcomes and quality of life in patients with CHF. Acknowledging the important role of educational interventions for improving self-care, we sought to assess a new educational strategy involving community health volunteers (CHVs) that could reduce the cost and, hypothetically, increase the effectiveness of self-care education in patients with CHF.Methods/Design: In this ongoing three-arm controlled trial, approved by two human research ethics committees in Australia and Iran, 231 patients with CHF registered at a referral cardiovascular hospital in Iran were randomly allocated into three groups -trained by community health volunteers at patients’ homes, rained by formal health professionals at hospital; and a control group with no formal educational exposure. Data obtained through interviewing participants and using the Persian self-care of CHF index (pSCHFI) before and two months after interventions will be analysed using SAS and SPSS.Discussion: The results of this study may help health service systems, especially in countries with limited resources, make use of community volunteers to teach patients with CHF to develop self-care behaviors and skills, reducing the cost of care and improving CHF outcomes. Also, this home-based educational strategy using face-to-face training, if successful, may provide psychosocial supports for patients suffering from chronic illnesses.Trial registration number: ACTRN12614000788673(Australian New Zealand Clinical Trials Registry)

    Local density of states at polygonal boundaries of d-wave superconductors

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    Besides the well-known existence of Andreev bound states, the zero-energy local density of states at the boundary of a d-wave superconductor strongly depends on the boundary geometry itself. In this work, we examine the influence of both a simple wedge-shaped boundary geometry and a more complicated polygonal or faceted boundary structure on the local density of states. For a wedge-shaped boundary geometry, we find oscillations of the zero-energy density of states in the corner of the wedge, depending on the opening angle of the wedge. Furthermore, we study the influence of a single Abrikosov vortex situated near a boundary, which is of either macroscopic or microscopic roughness.Comment: 10 pages, 11 figures; submitted to Phys. Rev.

    Two-subband quantum Hall effect in parabolic quantum wells

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    The low-temperature magnetoresistance of parabolic quantum wells displays pronounced minima between integer filling factors. Concomitantly the Hall effect exhibits overshoots and plateau-like features next to well-defined ordinary quantum Hall plateaus. These effects set in with the occupation of the second subband. We discuss our observations in the context of single-particle Landau fan charts of a two-subband system empirically extended by a density dependent subband separation and an enhanced spin-splitting g*.Comment: 5 pages, submitte

    Blood volume and orthostatic responses of men and women to a 13-day bedrest

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    Changes in blood volume during space flight are thought to contribute to decrements in postflight orthostatic function. The purpose of this study was to determine whether gender affects red cell mass and plasma volume during a short exposure to simulated microgravity, and whether gender differences in orthostatic tolerance ensure. Methods: Ten men (31.5 plus or minus 5.2 years, STD) and eleven normally menstruating women (33.3) plus or minus 6.0 STD) underwent 13 days of 6 degree head-down bedrest. Plasma volume (Iodine 125 labeled human serum albumin) and red cell mass (Carbon 51 labeled red blood cells) were measured before bedrest and on bedrest day 13. On the same days, orthostatic tolerance (OT) was determined as the maximal pressure during a presyncopalimited lower body negative pressure test. Results: Plasma volume (PV) and red cell mass (RCM) decreased in both groups with a greater PV decrease (P less than 0.05) in men (6.3 plus or minus 0.7 ml/kg) than in women (4.1 plus or minus 0.6 ml/kg). Decreases in red cell mass were similar (1.7 plus or minus 0.2 ml/kg in men and 1.7 plus or minus 0.2 ml/kg in women). OT was similar for men and women before bedrest (minus 78 plus or minus 6 mmHg in men versus minus 70 plus or minus 4 mmHg in women) and decreased by a similar degree (by an average of 11 mmHg in both groups) after bedrest. The changes in OT did not correlate with changes in plasma volume during bedrest (r(exp 2) = 0.002). Conclusion: Thus, although female hormones may protect PV during bedrest, they do no appear to offer an advantage in terms of loss of orthostatic function
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