4,162 research outputs found

    The political economy of quality measurement: a case study of the USA slaughter cattle market

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    As agricultural products move from being economic commodities to qualitydifferentiated goods, price dispersion within specific markets increases and implicit subsidies from high quality producers to low quality producers are removed. The present paper examines how these distributional effects can influence patterns of support and opposition to changes in marketing arrangements. The simple model developed is calibrated using data from the USA slaughter cattle market. Estimates of the impact on prices of measuring quality more accurately are found to be similar in size to previous estimates of market power price suppression in the market.Livestock Production/Industries,

    Understanding Algorithm Performance on an Oversubscribed Scheduling Application

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    The best performing algorithms for a particular oversubscribed scheduling application, Air Force Satellite Control Network (AFSCN) scheduling, appear to have little in common. Yet, through careful experimentation and modeling of performance in real problem instances, we can relate characteristics of the best algorithms to characteristics of the application. In particular, we find that plateaus dominate the search spaces (thus favoring algorithms that make larger changes to solutions) and that some randomization in exploration is critical to good performance (due to the lack of gradient information on the plateaus). Based on our explanations of algorithm performance, we develop a new algorithm that combines characteristics of the best performers; the new algorithms performance is better than the previous best. We show how hypothesis driven experimentation and search modeling can both explain algorithm performance and motivate the design of a new algorithm

    Improved sampling of the pareto-front in multiobjective genetic optimizations by steady-state evolution: a Pareto converging genetic algorithm

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    Previous work on multiobjective genetic algorithms has been focused on preventing genetic drift and the issue of convergence has been given little attention. In this paper, we present a simple steady-state strategy, Pareto Converging Genetic Algorithm (PCGA), which naturally samples the solution space and ensures population advancement towards the Pareto-front. PCGA eliminates the need for sharing/niching and thus minimizes heuristically chosen parameters and procedures. A systematic approach based on histograms of rank is introduced for assessing convergence to the Pareto-front, which, by definition, is unknown in most real search problems. We argue that there is always a certain inheritance of genetic material belonging to a population, and there is unlikely to be any significant gain beyond some point; a stopping criterion where terminating the computation is suggested. For further encouraging diversity and competition, a nonmigrating island model may optionally be used; this approach is particularly suited to many difficult (real-world) problems, which have a tendency to get stuck at (unknown) local minima. Results on three benchmark problems are presented and compared with those of earlier approaches. PCGA is found to produce diverse sampling of the Pareto-front without niching and with significantly less computational effort

    Associations of height, leg length, and lung function with cardiovascular risk factors in the Midspan Family Study

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    <b>Background</b>: Taller people and those with better lung function are at reduced risk of coronary heart disease (CHD). Biological mechanisms for these associations are not well understood, but both measures may be markers for early life exposures. Some studies have shown that leg length, an indicator of pre-pubertal nutritional status, is the component of height most strongly associated with CHD risk. Other studies show that height-CHD associations are greatly attenuated when lung function is controlled for. This study examines (1) the association of height and the components of height (leg length and trunk length) with CHD risk factors and (2) the relative strength of the association of height and forced expiratory volume in one second (FEV1) with risk factors for CHD. <b>Subjects and methods</b>: Cross sectional analysis of data collected at detailed cardiovascular screening examinations of 1040 men and 1298 women aged 30–59 whose parents were screened in 1972–76. Subjects come from 1477 families and are members of the Midspan Family Study. <b>Setting</b>: The towns of Renfrew and Paisley in the West of Scotland. <b>Results</b>: Taller subjects and those with better lung function had more favourable cardiovascular risk factor profiles, associations were strongest in relation to FEV1. Higher FEV1 was associated with lower blood pressure, cholesterol, glucose, fibrinogen, white blood cell count, and body mass index. Similar, but generally weaker, associations were seen with height. These associations were not attenuated in models controlling for parental height. Longer leg length, but not trunk length, was associated with lower systolic and diastolic blood pressure. Longer leg length was also associated with more favourable levels of cholesterol and body mass index than trunk length. <b>Conclusions</b>:These findings provide indirect evidence that measures of lung development and pre-pubertal growth act as biomarkers for childhood exposures that may modify an individual's risk of developing CHD. Genetic influences do not seem to underlie height-CHD associations

    Bullying in Graduate School: Its Nature and Effects

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    Does bullying exist in graduate school? If so, what does it look like? Semi-structured interviews were conducted with 22 graduate students from various departments at a medium-sized, Midwestern U.S. university. Grounded Theory methodology (Glaser, 1978) was utilized to gain insight into the terms and behaviors students used to define bullying in the graduate school context. Through constant comparative analysis (Stern, 1980), categories emerged that provided an understanding of the different perspectives inherent in a bully system, and the meanings attached to bullying behaviors. These findings can provide administrators and counselors with the information necessary to conduct preventative training to help students interact in a more professional, inclusive manner

    Pilot study of the safety and effect of adalimumab on pain, physical function, and musculoskeletal disease in mucopolysaccharidosis types I and II.

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    Mucopolysaccharidosis I and II are lysosomal storage disorders that, despite treatment with hematopoietic cell transplantation (HCT) and/or enzyme replacement therapy (ERT), continue to cause significant skeletal abnormalities leading to pain, stiffness, physical dysfunction, and short stature. Tumor necrosis factor - alpha (TNF-α) is elevated in individuals with MPS I and II and associated with pain and physical dysfunction. Therefore, we evaluated the safety and effects of the TNF-α inhibitor adalimumab in patients with MPS I and II in a 32-week, randomized, double blind, placebo-controlled, crossover study of adalimumab at a dose of 20 mg (weight 15-<30 kg) or 40 mg (weight ≥ 30 kg) administered subcutaneously every other week or saline placebo for 16 weeks. Participants were evaluated at baseline, week 16, and week 32 with the Children's Health Questionnaire - Parent Form 50 (CHQ-PF50), the Pediatric Pain Questionnaire (PPQ), range-of-motion (ROM) measurements, anthropometry, six-minute walk test (6MWT), hand dynamometer, and laboratory evaluations for safety. The primary outcome was safety and primary efficacy outcome was bodily pain (BP) measured by the CHQ-PF50. Two subjects, one with MPS I and one with MPS II, completed the study. Adalimumab was well tolerated and there were no serious adverse events. Standardized BP scores for age and gender were higher (i.e. less pain) at the end of the treatment versus placebo phase for both subjects. Subject #1 became unblinded during treatment due to skin erythema. Behavior measured by both CHQ-PF50 and parental report improved during treatment compared to placebo in both subjects. ROM improved by > 5° in seven of eight joints in Subject #1 and five of eight joints in Subject #2 (range 7.0° to 52.8°). There was no change in the PPQ, 6MWT, or hand dynamometer. Data from this small pilot study suggest that treatment with adalimumab is safe, tolerable, and may improve ROM, physical function, and possibly pain, in children with MPS I or II. However, additional clinical trials are needed before this therapy should be recommended as part of clinical care

    Researchers’ adoption of an institutional central fund for open-access article-processing charges: a case study using innovation diffusion theory

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    This article analyzes researchers’ adoption of an institutional central fund (or faculty publication fund) for open-access (OA) article-processing charges (APCs) to contribute to a wider understanding of take-up of OA journal publishing (“Gold” OA). Quantitative data, recording central fund usage at the University of Nottingham from 2006 to 2014, are analyzed alongside qualitative data from institutional documentation. The importance of the settings of U.K. national policy developments and international OA adoption trends are considered. Innovation Diffusion Theory (IDT) is used as an explanatory framework. It is shown that use of the central fund grew during the period from covering less than 1% of the University’s outputs to more than 12%. Health and Life Sciences disciplines made greatest use of the fund. Although highly variable, average APC prices rose during the period, with fully OA publishers setting lower average APCs. APCs were paid largely from internal funds, but external funding became increasingly important. Key factors in adoption are identified to be increasing awareness and changing perceptions of OA, communication, disciplinary differences, and adoption mandates. The study provides a detailed longitudinal analysis of one of the earliest central funds to be established globally with a theoretically informed explanatory model to inform future work on managing central funds and developing institutional and national OA policies

    Homeobox gene TGIF-1 is increased in placental endothelial cells of human fetal growth restriction.

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    Aberrant placental angiogenesis is associated with fetal growth restriction (FGR). In the mouse, targeted disruption of the homeobox gene, transforming growth β-induced factor (Tgif-1), which is also a transcription factor, causes defective placental vascularisation. Nevertheless, TGIF-1's role in human placental angiogenesis is unclear. We have previously reported increased TGIF-1 expression in human FGR placentae and demonstrated localisation of TGIF-1 protein in placental endothelial cells (ECs). However, its functional role remains to be investigated. In this study, we aimed to specifically compare TGIF-1 mRNA expression in placental ECs isolated from human FGR-affected pregnancies with gestation-matched control pregnancies in two independent cohorts from Australia and Canada, and to identify the functional role of TGIF-1 in placental angiogenesis using the human umbilical vein endothelial cell-derived cell line, SGHEC-7 and primary human umbilical vein ECs. Real-time PCR revealed that TGIF-1 mRNA expression was significantly increased in ECs isolated from FGR-affected placentae compared with that of controls. The functional roles of TGIF-1 were determined in ECs following TGIF-1 siRNA transfection. TGIF-1 inactivation in ECs significantly reduced TGIF-1 at both the mRNA and protein levels, as well as the proliferative and invasive potential, but significantly increased the angiogenic potential. Using angiogenesis PCR screening arrays, we identified ITGAV, NRP-1, ANPGT-1 and ANPGT-2 as novel downstream targets of TGIF-1, following TGIF-1 inactivation in ECs. Collectively, these results show that increased TGIF-1 in FGR may regulate EC function through mediating the expression of angiogenic molecules and contribute to aberrant placental angiogenesis in FGR pregnancies
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