1,396 research outputs found

    Wheat productivity estimates using LANDSAT data

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    The author has identified the following significant results. Large area LANDSAT yield estimates were generated. These results were compared with estimates computed using a meteorological yield model (CCEA). Both of these estimates were compared with Kansas Crop and Livestock Reporting Service (KCLRS) estimates of yield, in an attempt to assess the relative and absolute accuracy of the LANDSAT and CCEA estimates. Results were inconclusive. A large area direct wheat prediction procedure was implemented. Initial results have produced a wheat production estimate comparable with the KCLRS estimate

    But Is It Myopia? Risk Aversion and the Efficiency of Stock-Based Managerial Incentives

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    This paper points out that stock incentives do not lead to myopia unless they result in more emphasis on the short-term than would occur under an optimal contract. It shows that myopia findings relative to the standard used throughout the literature (first-best efficiency) are often reversed when evaluated relative to the relevant standard of optimal contracting. Results reported by the previous literature to be myopia often in fact have excessive emphasis on the long-term. The paper solves in closed-form for the region in parameter space which gives rise to these reversals and shows that it can be arbitrarily largehttp://deepblue.lib.umich.edu/bitstream/2027.42/49369/5/2008Jan16JCarmel.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/49369/1/Visiting-Carmel.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/49369/4/Visiting-Carmel.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/49369/7/1108_2008Jan16JCarmel.pd

    Validity and reliability of patient reported outcomes used in Psoriasis: results from two randomized clinical trials

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    BACKGROUND: Two Phase III randomized controlled clinical trials were conducted to assess the efficacy, safety, and tolerability of weekly subcutaneous administration of efalizumab for the treatment of psoriasis. Patient reported measures of psoriasis-related functionality and health-related quality of life and of psoriasis-related symptom assessments were included as part of the trials. OBJECTIVE: To assess the reliability, validity, and responsiveness of the patient reported outcome measures that were used in the trials – the Dermatology Life Quality Index (DLQI), the Psoriasis Symptom Assessment (PSA) Scale, and two itch measures, a Visual Analog Scale (VAS) and the National Psoriasis Foundation (NPF) itch measure. METHODS: Subjects aged 18 to 70 years with moderate to severe psoriasis for at least 6 months were recruited into the two clinical trials (n = 1095). Internal consistency reliability was evaluated for all patient reported outcomes at baseline and at 12 weeks. Construct validity was evaluated by relations among the different patient reported outcomes and between the patient reported outcomes and the clinical assessments (Psoriasis Area and Severity Index; Overall Lesion Severity Scale; Physician's Global Assessment of Change) assessed at baseline and at 12 weeks, as was the change over the course of the 12 week portion of the trial. RESULTS: Internal consistency reliability ranged from 0.86 to 0.95 for the patient reported outcome measures. The patient reported outcome measures were all shown to have significant construct validity with respect to each other and with respect to the clinical assessments. The four measures also demonstrated significant responsiveness to change in underlying clinical status of the patients over the course of the trial, as measured by the independently assessed clinical outcomes. CONCLUSIONS: The DLQI, the PSA, VAS, and the NPF are considered useful tools for the measurement of dermatology-related limitations of functional ability and the frequency, severity and impact of psoriasis symptoms on patients' lives and psoriasis-related quality of life

    Restenosis after directional coronary atherectomy: Differences between primary atheromatoes and restenosls lesions and influence of subintimal tissue resection

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    AbstractRates of restenosis were evaluated in 70 patients (74 lesions) after successful directional coronary atherectomy. The extent of vascular tissue resection was correlated with restenosis rates for coronary (n = 59) and vein bypass graft (n = 15) lesions.After 6 months, the overall restenosis rate was 50% (37 of 74 lesions); it was 42% (15 of 36 lesions) when intima alone was resected, 50% (7 of 14 lesions) when media was resected and 63% (15 of 24 lesions) when adventitia was resected. Subintimal tissue resection increased the restenosis rate for vein grafts (43% with intimal resection versus 100% with subintimal resection, p = 0.01) but not for coronary arteries (50% versus 48%). There was no overall difference in restenosis rates after atherectomy between primary lesions and restenosis lesions that occurred after balloon angioplasty (46% versus 54%). Among postballoon angioplasty restenosis lesions, a higher rate of restenosis after atherectomy was found with subintimal than with intimal resection (78% versus 32%, p = 0.01).Tissues from patients undergoing a second atherectomy for restenosis after initial atherectomy (n = 8) demonstrated neointimal hyperplasia that appeared histotogically identical to restenotic tissue developing after balloon angioplasty (n = 37).These data suggest that the cellular response to directional coronary atherectomy is characterized by neointimal proliferation similar to that which may develop after balloon angioplasty. The extent of fibrous hyperplasia appears to be related to the depth of tissue resection in vein graft lesions and coronary artery restenosis lesions that occur after balloon angioplasty but not in primary atheromatous coronary artery lesions

    Chain-store pricing and the structure of retail markets

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    This paper examines competition between chain-stores and independent retailers in the UK retail opticians' market. We demonstrate that the pricing policy adopted by chain-stores can determine the impact their entry has on independent retailers. Crucially, in this market the chain-store retailers set an identical national price across all local markets. Our results suggest that this pricing strategy lessens the detrimental effect competition from chain-stores has on independent retailers

    Cluster Performance reconsidered: Structure, Linkages and Paths in the German Biotechnology Industry, 1996-2003

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    This paper addresses the evolution of biotechnology clusters in Germany between 1996 and 2003, paying particular attention to their respective composition in terms of venture capital, basic science institutions and biotechnology firms. Drawing upon the significance of co-location of "money and ideas", the literature stressing the importance of a cluster's openness and external linkages, and the path dependency debate, the paper aims to analyse how certain cluster characteristics correspond with its overall performance. After identifying different cluster types, we investigate their internal and external interconnectivity in comparative manner and draw on changes in cluster composition. Our results indicate that the structure, i.e. to which group the cluster belongs, and the openness towards external knowledge flows deliver merely unsystematic indications with regard to a cluster's overall success. Its ability to change composition towards a more balanced ratio of science and capital over time, on the other hand, turns out as a key explanatory factor. Hence, the dynamic perspective proves effective illuminating cluster growth and performance, where our explorative findings provide a promising avenue for further evolutionary research

    Compressed magnetized shells of atomic gas and the formation of the Corona Australis molecular cloud

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    We present the identification of the previously unnoticed physical association between the Corona Australis molecular cloud (CrA), traced by interstellar dust emission, and two shell-like structures observed with line emission of atomic hydrogen (HI) at 21 cm. Although the existence of the two shells had already been reported in the literature, the physical link between the HI emission and CrA had never been highlighted until now. We used both Planck and Herschel data to trace dust emission and the Galactic All Sky HI Survey (GASS) to trace HI. The physical association between CrA and the shells is assessed based both on spectroscopic observations of molecular and atomic gas and on dust extinction data with Gaia. The shells are located at a distance between ~140 and ~190 pc, which is comparable to the distance of CrA, which we derived as (150.5 ± 6.3) pc. We also employed dust polarization observations from Planck to trace the magnetic- field structure of the shells. Both of them show patterns of magnetic-field lines following the edge of the shells consistently with the magnetic-field morphology of CrA. We estimated the magnetic-field strength at the intersection of the two shells via the Davis-Chandrasekhar-Fermi (DCF) method. Despite the many caveats that are behind the DCF method, we find a magnetic-field strength of (27 ± 8) μG, which is at least a factor of two larger than the magnetic-field strength computed off of the HI shells. This value is also significantly larger compared to the typical values of a few μG found in the diffuse HI gas from Zeeman splitting. We interpret this as the result of magnetic-field compression caused by the shell expansion. This study supports a scenario of molecular-cloud formation triggered by supersonic compression of cold magnetized HI gas from expanding interstellar bubbles
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