5,045 research outputs found
Comparative theoretical study of the Ag-MgO (100) and (110) interfaces
We have calculated the atomic and electronic structures of Ag-MgO(100) and (110) interfaces using a periodic (slab) model and an ab initio Hartree-Fock approach with a posteriori electron correlation corrections. The electronic structure information includes interatomic bond populations, effective charges, and multipole moments of ions. This information is analyzed in conjunction with the interface binding energy and the equilibrium distances for both interfaces for various coverages. There are significant differences between partly covered surfaces and surfaces with several layers of metal, and these can be understood in terms of electrostatics and the electron density changes.For complete monolayer (1:1) coverage of the perfect MgO(100) surface, the most favorable adsorption site energetically for the Ag atom is above the surface oxygen. However, for partial (1:4) coverage of the same surface, the binding energies are very close for all the three likely adsorption positions (Ag over O, Ag over Mg, Ag over a gap position),For a complete (1:1) Ag monolayer coverage of the perfect MgO(110) interface, the preferable Ag adsorption site is over the interatomic gap position, whereas for an Ag bilayer coverage the preferred Ag site is above the subsurface Mg2+ ion (the bridge site between two nearest surface O2- ions). In the case of 1:2 layer coverage, both sites are energetically equivalent. These two adhesion energies for the (110) substrate are by a factor of two to three larger than over other possible adsorption sites on perfect(110) or (100) surfaces.We compare our atomistic calculations for one to three Ag planes with those obtained by the shell model for 10 Ag planes and the Image Interaction Model addressing the case of thick metal layers. Qualitatively, our ab initio results agree well with many features of these models. The main charge redistributions are well in line with those expected from the Image Model. There is also broad agreement in regard to orders of magnitude of energies. (C) 1999 Elsevier Science B.V. All rights reserved
Inequality and Electoral Accountability: Class-Biased Economic Voting in Comparative Perspective
Do electorates hold governments accountable for the distribution of economic welfare? Building on the finding of “class-biased economic voting” in the United States, we exam- ine how OECD electorates respond to alternative distributions of income gains and losses. Drawing on individual-level electoral data and aggregate election results across 15 advanced democracies, we examine whether lower- and middle-income voters defend their distributive interests by punishing governments for concentrating income gains among the rich. We find no indication that non-rich voters punish rising inequality, and substantial evidence that electorates positively reward the concentration of aggregate income growth at the top. Our results suggest that governments commonly face political incentives systematically skewed in favor of inegalitarian economic outcomes. At the same time, we find that the electorate’s tolerance of rising inequality has its limits: class biases in economic voting diminish as the income shares of the rich grow in magnitude
Whose News? Class-Biased Economic News in the United States
There is substantial evidence that voters’ choices are shaped by assessments of the state of the economy and that these assessments, in turn, are influenced by the news. But how does the economic news track the welfare of different income groups in an era of rising inequality? Whose economy does the news cover? Drawing on a large new dataset of US news content, we demonstrate that the tone of the economic news strongly and disproportionately tracks the fortunes of the richest households, with little sensitivity to income changes among the non-rich. Further, we present evidence that this pro-rich bias emerges not from pro-rich journalistic preferences but, rather, from the interaction of the media’s focus on economic aggregates with structural features of the relationship between economic growth and distribution. The findings yield a novel explanation of distributionally perverse electoral patterns and demonstrate how distributional biases in the economy condition economic accountability
Contemporary medical television and crisis in the NHS
This article maps the terrain of contemporary UK medical television, paying particular attention to Call the Midwife as its centrepiece, and situating it in contextual relation to the current crisis in the NHS. It provides a historical overview of UK and US medical television, illustrating how medical television today has been shaped by noteworthy antecedents. It argues that crisis rhetoric surrounding healthcare leading up to the passing of the Health and Social Care Act 2012 has been accompanied by a renaissance in medical television. And that issues, strands and clusters have emerged in forms, registers and modes with noticeable regularity, especially around the value of affective labour, the cultural politics of nostalgia and the neoliberalisation of healthcare
Patient-reported gout attack frequency and allopurinol use in general practice in the Netherlands: a prospective observational cohort study protocol
Missing data is poorly handled and reported in prediction model studies using machine learning: a literature review
OBJECTIVES: Missing data is a common problem during the development, evaluation, and implementation of prediction models. Although machine learning (ML) methods are often said to be capable of circumventing missing data, it is unclear how these methods are used in medical research. We aim to find out if and how well prediction model studies using machine learning report on their handling of missing data. STUDY DESIGN AND SETTING: We systematically searched the literature on published papers between 2018 and 2019 about primary studies developing and/or validating clinical prediction models using any supervised ML methodology across medical fields. From the retrieved studies information about the amount and nature (e.g. missing completely at random, potential reasons for missingness) of missing data and the way they were handled were extracted. RESULTS: We identified 152 machine learning-based clinical prediction model studies. A substantial amount of these 152 papers did not report anything on missing data (n = 56/152). A majority (n = 96/152) reported details on the handling of missing data (e.g., methods used), though many of these (n = 46/96) did not report the amount of the missingness in the data. In these 96 papers the authors only sometimes reported possible reasons for missingness (n = 7/96) and information about missing data mechanisms (n = 8/96). The most common approach for handling missing data was deletion (n = 65/96), mostly via complete-case analysis (CCA) (n = 43/96). Very few studies used multiple imputation (n = 8/96) or built-in mechanisms such as surrogate splits (n = 7/96) that directly address missing data during the development, validation, or implementation of the prediction model. CONCLUSION: Though missing values are highly common in any type of medical research and certainly in the research based on routine healthcare data, a majority of the prediction model studies using machine learning does not report sufficient information on the presence and handling of missing data. Strategies in which patient data are simply omitted are unfortunately the most often used methods, even though it is generally advised against and well known that it likely causes bias and loss of analytical power in prediction model development and in the predictive accuracy estimates. Prediction model researchers should be much more aware of alternative methodologies to address missing data
Necrotic gangrenous intrathoracic appendix in a marfanoid adult patient: a case report
BACKGROUND: A diaphragmatic hernia is defined as a defect in part of the diaphragm through which abdominal contents can protrude into the thorax. It may be congenital or acquired. In this case report, we aim to demonstrate a congenital diaphragmatic hernia in an adult marfanoid patient which required emergency treatment CASE PRESENTATION: A 43 year old woman was admitted with classical appendicitis requiring surgery. She incidentally had Marfan's clinical features with a positive family history for the syndrome. At operation she had grossly abnormal abdominal anatomy. Radiological investigations demonstrated a large right congenital diaphragmatic hernia with an intrathoracic hernial sac containing a perforated gangrenous appendix. The hernial sac was opened surgically and the appendix excised. The patient made a full recovery. CONCLUSION: Diaphragmatic hernias are usually congenital in nature often requiring early corrective surgery for future survival. We have demonstrated the presence of an unusually large diaphragmatic defect, almost a hemidiaphragmatic defect, of unknown direct etiology, but of some possible association with Marfan's syndrome in an adult patient presenting with an acute perforated gangrenous appendix requiring emergency life-saving surgery
Monitoring cow comfort and rumen health indices in a cubicle-housed herd with an automatic milking system: a repeated measures approach
Australian human research ethics committee members' confidence in reviewing genomic research applications.
Human research ethics committees (HRECs) are evaluating increasing quantities of genomic research applications with complex ethical considerations. Genomic confidence is reportedly low amongst many non-genetics-experts; however, no studies have evaluated genomic confidence levels in HREC members specifically. This study used online surveys to explore genomic confidence levels, predictors of confidence, and genomics resource needs of members from 185 HRECs across Australia. Surveys were fully or partially completed by 145 members. All reported having postgraduate 94 (86%) and/or bachelor 15 (14%) degrees. Participants consisted mainly of researchers (n = 45, 33%) and lay members (n = 41, 30%), affiliated with either public health services (n = 73, 51%) or public universities (n = 31, 22%). Over half had served their HREC [Formula: see text]3 years. Fifty (44%) reviewed genomic studies [Formula: see text]3 times annually. Seventy (60%) had undertaken some form of genomic education. While most (94/103, 91%) had high genomic literacy based on familiarity with genomic terms, average genomic confidence scores (GCS) were moderate (5.7/10, n = 119). Simple linear regression showed that GCS was positively associated with years of HREC service, frequency of reviewing genomic applications, undertaking self-reported genomic education, and familiarity with genomic terms (p < 0.05 for all). Conversely, lay members and/or those relying on others when reviewing genomic studies had lower GCSs (p < 0.05 for both). Most members (n = 83, 76%) agreed further resources would be valuable when reviewing genomic research applications, and online courses and printed materials were preferred. In conclusion, even well-educated HREC members familiar with genomic terms lack genomic confidence, which could be enhanced with additional genomic education and/or resources
Parametric polymorphism - universally
In the 1980s, John Reynolds postulated that a parametrically polymorphic function is an ad-hoc polymorphic function satisfying a uniformity principle. This allowed him to prove that his set-theoretic semantics has a relational lifting which satisfies the Identity Extension Lemma and the Abstraction Theorem. However, his definition (and subsequent variants) have only been given for specific models. In contrast, we give a model-independent axiomatic treatment by characterising Reynolds' definition via a universal property, and show that the above results follow from this universal property in the axiomatic setting
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