5,520 research outputs found

    De Gustibus non est Taxandum: Heterogeneity in Preferences and Optimal Redistribution

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    The prominent but unproven intuition that preference heterogeneity reduces re-distribution in a standard optimal tax model is shown to hold under the plausible condition that the distribution of preferences for consumption relative to leisure rises, in terms of first-order stochastic dominance, with income. Given mainstream functional form assumptions on utility and the distributions of ability and preferences, a simple statistic for the effect of preference heterogeneity on marginal tax rates is derived. Numerical simulations and suggestive empirical evidence demonstrate the link between this potentially measurable statistic and the quantitative implications of preference heterogeneity for policy.

    The size and shape of the oblong dwarf planet Haumea

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    We use thermal radiometry and visible photometry to constrain the size, shape, and albedo of the large Kuiper belt object Haumea. The correlation between the visible and thermal photometry demonstrates that Haumea's high amplitude and quickly varying optical light curve is indeed due to Haumea's extreme shape, rather than large scale albedo variations. However, the well-sampled high precision visible data we present does require longitudinal surface heterogeneity to account for the shape of lightcurve. The thermal emission from Haumea is consistent with the expected Jacobi ellipsoid shape of a rapidly rotating body in hydrostatic equilibrium. The best Jacobi ellipsoid fit to the visible photometry implies a triaxial ellipsoid with axes of length 1920 x 1540 x 990 km and density 2.6 g cm^-3$, as found by Lellouch et al(2010). While the thermal and visible data cannot uniquely constrain the full non-spherical shape of Haumea, the match between the predicted and measured thermal flux for a dense Jacobi ellipsoid suggests that Haumea is indeed one of the densest objects in the Kuiper belt.Comment: 21 pages, 2 figures, 2 tables -- Accepted for publication in Earth, Moon and Planet

    Intraorbital foreign body detection and localisation by radiographers: a preliminary JAFROC observer performance study

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    Introduction - The purpose of this study was to run a preliminary investigation to establish if a short course of learning would increase radiographers’ performance in intraorbital foreign body (IOFB) detection and localisation on pre-magnetic resonance imaging (MRI) orbital computed radiographs (CR). Method - A multi-reader multi-case (MRMC) human observer study was performed. Fifteen radiographers from 5 hospitals participated. Each radiographer reviewed a pre- and post-training image bank and was instructed to identify the presence or absence of IOFBs, indicating the lesion location on each case whilst scoring the detection using a confidence index on a 5-point scale, for 30 orbital radiographs. The results were analysed using a Jackknife free-response receiver operating characteristic (JAFROC2 equal weighted) methodology. Results -The performance of the radiographers demonstrated a statistically significant difference after a short period of training in the detection of IOFBs on orbital radiographs (F (1,14)= 12.99, df = 14.0, p = 0.0029). The JAFROC2 analysis averaged figure of merit (FOM) for the radiographers was 0.818 (95% CI 0.769, 0.867) pre-training and 0.920 (95% CI 0.891, 0.950) post-training. Conclusion - These results suggest that with a short programme of learning in image interpretation for IOFBs in orbital radiographs, radiographers should be able to achieve a high level of accuracy in the identification and localisation of IOFBs prior to MRI examination

    Applying theory informed global trends in a collaborative model for organizational evidence-based healthcare

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    Getting evidence in to practice tends to focus on strategies, theories and studies that aim to close the gap between research knowledge and clinical practice. The evidence to practice gap is more about systems than individual clinician decision making. The absence of evidence for administration and management in the organization of healthcare is persistent. Teaching nurses and providing evidence as the solution to evidence-based healthcare is no longer axiomatic. Previous studies have concluded that unit level strategies integrate multi-professional teams with organizational needs and priorities. This ‘best fit’ approach that characterizes how healthcare is structured and delivered. The published literature shows that increased readiness for change is aligned with integrated approaches informed by conceptual models. The Joanna Briggs Collaboration is the largest global collaboration to integrate evidence within a theory informed model that brings together academic centres, hospitals and health systems for evidence synthesis, transfer and implementation. The best approaches to implementation are tailored to local culture and context, benchmark against international evidence, combine a theory informed model and stakeholder perspectives to improve the structure and processes of health care policy and practice.Craig Lockwoo

    Care of transgender patients by diagnostic radiographers: What can be learnt from the literature

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    Introduction: Transgender patients have described negative healthcare experiences, including discrimination and feeling unwelcome. Additionally, these patients are at risk of inadequate or unsafe care due to healthcare providers being unable to obtain and record transgender patients’ correct gender and assigned birth sex. This literature review aims to review radiology and radiographer articles published since 2018 about transgender healthcare issues and make recommendations that can be applied by diagnostic radiographers, their managers and diagnostic radiography programme providers. Method: A literature search used multiple databases containing peer-reviewed articles. Boolean operators and key words were utilised. Identified articles were searched to identify any articles not found by searching the databases. Themes and sub-themes from each paper were identified and discussed. Results: Three key themes were identified: education, systems and environment. Education sub-themes were knowledge and awareness. Systems sub-themes were recording gender correctly and discriminating/stigmatising policies. Environment sub-themes were transgender-friendly symbols and environmental dysphoria. Conclusion: Transgender patients still face barriers to equitable care. Several recommendations were made based on the thematic discussion that could be applied by diagnostic radiographers, student radiographers, radiology managers, University training providers, and professional body organisations. Diagnostic radiography programmes should include training on both clinical topics and cultural competence. Radiology managers should display transgender-positive symbols in their departments and ensure their policies are non-discriminatory and non-stigmatising. Radiology hardware and software providers should provide the ability to record non-binary genders and birth-assigned sex. Implications for Practice: Transgender patients have the right to receive equitable care from diagnostic radiographers during their imaging examination and radiology attendance, and that any risks relating to their transgender status should be correctly managed with appropriate sensitivity

    Still I Love Thee

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    https://digitalcommons.library.umaine.edu/mmb-vp/6693/thumbnail.jp

    MECHANICAL AND ELECTROMYGRAPHICAL ANALYSIS OF A BOXER'S JAB

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    INTRODUCTION Very little data exists about the mechanics of maximum force production of a boxeris jab. The purpose of this study was to determine the kinematics and muscular activity during a maximum force jab. Additionally, to determine if differences exist between professional (PRO) and amateurs (AM') boxers during recruitment of both the upper and lower body musculature. METHODS L Four PRO and five AMT boxers (age: 24.2k1.02 yrs; wgt: 81.7+ 8.13 kg; %BF: 11.99+2.6%) volunteered as subjects. Two dimensional kinematic data were collected with a Panasonic AG-500 video camera, operating at 30 Hz. Pre-amplified electrodes were placed on the gastrocnemius (GA), rectus femoris (RF), biceps femoris (BF), external oblique (EO), serratus anterior (SA), pectoralis major-sternal (PEC), anterior deltoid (AD), and tricep brachii (TRI). The EMG data and kinematic data were analyzed with the Ariel Performance Analysis System. Force measures were obtained from an instrumented boxing bag. Subjects performed three trials, after digitizing all trials, the trial with maximum linear velocity at the wrist was selected for further analysis. RESULTS Pearson product-moment correlations were conducted between the force production on the bag and muscle recruitment. The results indicate a significant relationship between force and the BF (r = .47), EO (r = .59) and PEC (r = .60). Tko-sample t-tests were conducted between PRO and AMT force and kinematic data. Significant differences (p < 0.05) were found in force production (t(6) = 2.65), wrist velocity (t(6) = 2.47) and elbow velocity (t(6) = 2.1 1). No significant differences were found between PRO and AMT recruitment of upper and lower body muscles. DISCUSSION The PRO boxers hit the bag harder with increased linear velocity of the wrist and elbow. Although no differences were found in muscle activation between the two groups, the duration and timing of the activation appears to favor the PRO. Because of the relationships found a weight training or resistance training program emphasizing leg extension, abdominal crunches, and shoulder flexion would assist the boxer in production of maximum force. The traditional conditioning program of a boxer (jumping rope, sit-ups, push-ups) would appear to address the boxers needs for both speed and force
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