208 research outputs found

    Variational Approximations in a Path-Integral Description of Potential Scattering

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    Using a recent path integral representation for the T-matrix in nonrelativistic potential scattering we investigate new variational approximations in this framework. By means of the Feynman-Jensen variational principle and the most general ansatz quadratic in the velocity variables -- over which one has to integrate functionally -- we obtain variational equations which contain classical elements (trajectories) as well as quantum-mechanical ones (wave spreading).We analyse these equations and solve them numerically by iteration, a procedure best suited at high energy. The first correction to the variational result arising from a cumulant expansion is also evaluated. Comparison is made with exact partial-wave results for scattering from a Gaussian potential and better agreement is found at large scattering angles where the standard eikonal-type approximations fail.Comment: 35 pages, 3 figures, 6 tables, Latex with amsmath, amssymb; v2: 28 pages, EPJ style, misprints corrected, note added about correct treatment of complex Gaussian integrals with the theory of "pencils", matches published versio

    Numeric and Traffic Light Calorie Labels on Cafeteria Menus: Noticing, Use, and Perceptions Among Young Adults

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    This is a pre-copyedited, author-produced version of an article accepted for publication in Current Developments in Nutrition following peer review. The version of record Lee, K., Hammond, D., Price, M., Hobin, E., Wallace, M., Olstad, D., Minaker, L., & Kirkpatrick, S. (2020). Numeric and Traffic Light Calorie Labels on Cafeteria Menus: Noticing, Use, and Perceptions Among Young Adults. Current Developments in Nutrition, 4(Supplement_2), 1719. https://doi.org/10.1093/cdn/nzaa064_009 is available online at: https://doi.org/10.1093/cdn/nzaa064_009.Objectives The objective of this study was to examine the impact of numeric versus interpretive calorie labelling on consumer noticing, use, and perceptions of labels. We hypothesized that due to their at-a-glance format, interpretive labels would outperform numeric labels. Methods Using a pre-post quasi-experimental controlled trial design, three campus cafeterias were randomized to receive numeric calorie labelling, traffic light labelling (i.e., red, amber, or green symbol indicating the number of calories), or no labelling for two weeks. Exit surveys were conducted with cafeteria patrons prior to (n = 949) and following (n = 1110) implementation of labels. Surveys queried sociodemographic characteristics, the details of the most recent cafeteria purchase, and noticing, use, and perceptions of labels. Chi-squared tests and multinomial logistic regression were used to determine the impact of format on label noticing, use, and perceptions. Results Label noticing increased from 23% to 43% among those exposed to numeric labels and 28% to 63% among those exposed to traffic light labels, compared to no change in the control (15%) (P 0.05). Conclusions Cafeteria patrons exposed to calorie labels reported noticing and using them, with higher salience for traffic light labels. The implementation of such interpretive labels at the point-of-purchase may provide cues to enable consumers to make informed choices, consistent with front-of-pack labels on packaged foods under consideration in many jurisdictions.Funder 1,Kirsten Lee is funded by an Ontario Graduate Scholarship ||. Funder 2, This study is funded by the Canadian Foundation for Dietetic Research ||. Funder 3, an Ontario Ministry of Research and Innovation Early Researcher Award held by Sharon Kirkpatrick

    ‘Speaking Truth’ Protects Underrepresented Minorities’ Intellectual Performance and Safety in STEM

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    We offer and test a brief psychosocial intervention, Speaking Truth to EmPower (STEP), designed to protect underrepresented minorities’ (URMs) intellectual performance and safety in science, technology, engineering, and math (STEM). STEP takes a ‘knowledge as power’ approach by: (a) providing a tutorial on stereotype threat (i.e., a social contextual phenomenon, implicated in underperformance and early exit) and (b) encouraging URMs to use lived experiences for generating be-prepared coping strategies. Participants were 670 STEM undergraduates [URMs (Black/African American and Latina/o) and non-URMs (White/European American and Asian/Asian American)]. STEP protected URMs’ abstract reasoning and class grades (adjusted for grade point average [GPA]) as well as decreased URMs’ worries about confirming ethnic/racial stereotypes. STEP’s two-pronged approach—explicating the effects of structural ‘isms’ while harnessing URMs’ existing assets—shows promise in increasing diversification and equity in STEM

    Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

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    Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

    A meta-analysis and critical review of prospective memory in autism spectrum disorder

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    Prospective memory (PM) is the ability to remember to carry out a planned intention at an appropriate moment in the future. Research on PM in ASD has produced mixed results. We aimed to establish the extent to which two types of PM (event-based/time-based) are impaired in ASD. In part 1, a meta-analysis of all existing studies indicates a large impairment of time-based, but only a small impairment of event-based, PM in ASD. In Part 2, a critical review concludes that time-based PM appears diminished in ASD, in line with the meta-analysis, but that caution should be taken when interpreting event-based PM findings, given potential methodological limitations of several studies. Clinical implications and directions for future research are discussed

    Performance of the 2019 EULAR/ACR classification criteria for systemic lupus erythematosus in early disease, across sexes and ethnicities.

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    Funder: American College of Rheumatology Research and Education Foundation; FundRef: http://dx.doi.org/10.13039/100000960Funder: National Institute of Arthritis and Musculoskeletal and Skin Diseases; FundRef: http://dx.doi.org/10.13039/100000069Funder: European League Against Rheumatism; FundRef: http://dx.doi.org/10.13039/501100008741OBJECTIVES: The European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) 2019 Classification Criteria for systemic lupus erythematosus (SLE) have been validated with high sensitivity and specificity. We evaluated the performance of the new criteria with regard to disease duration, sex and race/ethnicity, and compared its performance against the Systemic Lupus International Collaborating Clinics (SLICC) 2012 and ACR 1982/1997 criteria. METHODS: Twenty-one SLE centres from 16 countries submitted SLE cases and mimicking controls to form the validation cohort. The sensitivity and specificity of the EULAR/ACR 2019, SLICC 2012 and ACR 1982/1997 criteria were evaluated. RESULTS: The cohort consisted of female (n=1098), male (n=172), Asian (n=118), black (n=68), Hispanic (n=124) and white (n=941) patients; with an SLE duration of 1 to <3 years (n=196) and ≄5 years (n=879). Among patients with 1 to <3 years disease duration, the EULAR/ACR criteria had better sensitivity than the ACR criteria (97% vs 81%). The EULAR/ACR criteria performed well in men (sensitivity 93%, specificity 96%) and women (sensitivity 97%, specificity 94%). Among women, the EULAR/ACR criteria had better sensitivity than the ACR criteria (97% vs 83%) and better specificity than the SLICC criteria (94% vs 82%). Among white patients, the EULAR/ACR criteria had better sensitivity than the ACR criteria (95% vs 83%) and better specificity than the SLICC criteria (94% vs 83%). The EULAR/ACR criteria performed well among black patients (sensitivity of 98%, specificity 100%), and had better sensitivity than the ACR criteria among Hispanic patients (100% vs 86%) and Asian patients (97% vs 77%). CONCLUSIONS: The EULAR/ACR 2019 criteria perform well among patients with early disease, men, women, white, black, Hispanic and Asian patients. These criteria have superior sensitivity than the ACR criteria and/or superior specificity than the SLICC criteria across many subgroups
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