4,095 research outputs found

    Langevin analysis for time-nonlocal Brownian motion with algebraic memories and delay interactions

    Get PDF
    Starting from a Langevin equation with memory describing the attraction of a particle to a center, we investigate its transport and response properties corresponding to two special forms of the memory: one is algebraic, i.e., power-law, and the other involves a delay. We examine the properties of the Green function of the Langevin equation and encounter Mittag-Leffler and Lambert W-functions well-known in the literature. In the presence of white noise, we study two experimental situations, one involving the motional narrowing of spectral lines and the other the steady-state size of the particle under consideration. By comparing the results to counterparts for a simple exponential memory, we uncover instructive similarities and differences. Perhaps surprisingly, we find that the Balescu-Swenson theorem that states that non-Markoffian equations do not add anything new to the description of steady-state or equilibrium observables is violated for our system in that the saturation size of the particle in the steady-state depends on the memory function utilized. A natural generalization of the Smoluchowski equation for the time-local case is examined and found to satisfy the Balescu-Swenson theorem and describe accurately the first moment but not the second and higher moments. We also calculate two-time correlation functions for all three cases of the memory, and show how they differ from (tend to) their Markoffian counterparts at small (large) values of the difference between the two times

    Langevin analysis for time-nonlocal Brownian motion with algebraic memories and delay interactions

    Get PDF
    Starting from a Langevin equation with memory describing the attraction of a particle to a center, we investigate its transport and response properties corresponding to two special forms of the memory: one is algebraic, i.e., power-law, and the other involves a delay. We examine the properties of the Green function of the Langevin equation and encounter Mittag-Leffler and Lambert W-functions well-known in the literature. In the presence of white noise, we study two experimental situations, one involving the motional narrowing of spectral lines and the other the steady-state size of the particle under consideration. By comparing the results to counterparts for a simple exponential memory, we uncover instructive similarities and differences. Perhaps surprisingly, we find that the Balescu-Swenson theorem that states that non-Markoffian equations do not add anything new to the description of steady-state or equilibrium observables is violated for our system in that the saturation size of the particle in the steady-state depends on the memory function utilized. A natural generalization of the Smoluchowski equation for the time-local case is examined and found to satisfy the Balescu-Swenson theorem and describe accurately the first moment but not the second and higher moments. We also calculate two-time correlation functions for all three cases of the memory, and show how they differ from (tend to) their Markoffian counterparts at small (large) values of the difference between the two times

    School-based self-management interventions for asthma in children and adolescents: a mixed methods systematic review.

    Get PDF
    BACKGROUND: Asthma is a common respiratory condition in children that is characterised by symptoms including wheeze, shortness of breath, chest tightness, and cough. Children with asthma may be able to manage their condition more effectively by improving inhaler technique, and by recognising and responding to symptoms. Schools offer a potentially supportive environment for delivering interventions aimed at improving self-management skills among children. The educational ethos aligns with skill and knowledge acquisition and makes it easier to reach children with asthma who do not regularly engage with primary care. Given the multi-faceted nature of self-management interventions, there is a need to understand the combination of intervention features that are associated with successful delivery of asthma self-management programmes. OBJECTIVES: This review has two primary objectives.• To identify the intervention features that are aligned with successful intervention implementation.• To assess effectiveness of school-based interventions provided to improve asthma self-management among children.We addressed the first objective by performing qualitative comparative analysis (QCA), a synthesis method described in depth later, of process evaluation studies to identify the combination of intervention components and processes that are aligned with successful intervention implementation.We pursued the second objective by undertaking meta-analyses of outcomes reported by outcome evaluation studies. We explored the link between how well an intervention is implemented and its effectiveness by using separate models, as well as by undertaking additional subgroup analyses. SEARCH METHODS: We searched the Cochrane Airways Trials Register for randomised studies. To identify eligible process evaluation studies, we searched MEDLINE, Embase, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), PsycINFO, the Cochrane Database of Systematic Reviews (CDSR), Web of Knowledge, the Database of Promoting Health Effectiveness Reviews (DoPHER), the Database of Abstracts of Reviews of Effects (DARE), the International Biography of Social Science (IBSS), Bibliomap, Health Technology Assessment (HTA), Applied Social Sciences Index and Abstracts (ASSIA), and Sociological Abstracts (SocAbs). We conducted the latest search on 28 August 2017. SELECTION CRITERIA: Participants were school-aged children with asthma who received the intervention in school. Interventions were eligible if their purpose was to help children improve management of their asthma by increasing knowledge, enhancing skills, or changing behaviour. Studies relevant to our first objective could be based on an experimental or quasi-experimental design and could use qualitative or quantitative methods of data collection. For the second objective we included randomised controlled trials (RCTs) where children were allocated individually or in clusters (e.g. classrooms or schools) to self-management interventions or no intervention control. DATA COLLECTION AND ANALYSIS: We used qualitative comparative analysis (QCA) to identify intervention features that lead to successful implementation of asthma self-management interventions. We measured implementation success by reviewing reports of attrition, intervention dosage, and treatment adherence, irrespective of effects of the interventions.To measure the effects of interventions, we combined data from eligible studies for our primary outcomes: admission to hospital, emergency department (ED) visits, absence from school, and days of restricted activity due to asthma symptoms. Secondary outcomes included unplanned visits to healthcare providers, daytime and night-time symptoms, use of reliever therapies, and health-related quality of life as measured by the Asthma Quality of Life Questionnaire (AQLQ). MAIN RESULTS: We included 55 studies in the review. Thirty-three studies in 14,174 children provided information for the QCA, and 33 RCTs in 12,623 children measured the effects of interventions. Eleven studies contributed to both the QCA and the analysis of effectiveness. Most studies were conducted in North America in socially disadvantaged populations. High school students were better represented among studies contributing to the QCA than in studies contributing to effectiveness evaluations, which more commonly included younger elementary and junior high school students. The interventions all attempted to improve knowledge of asthma, its triggers, and stressed the importance of regular practitioner review, although there was variation in how they were delivered.QCA results highlighted the importance of an intervention being theory driven, along with the importance of factors such as parent involvement, child satisfaction, and running the intervention outside the child's own time as drivers of successful implementation.Compared with no intervention, school-based self-management interventions probably reduce mean hospitalisations by an average of about 0.16 admissions per child over 12 months (SMD -0.19, 95% CI -0.35 to -0.04; 1873 participants; 6 studies, moderate certainty evidence). They may reduce the number of children who visit EDs from 7.5% to 5.4% over 12 months (OR 0.70, 95% CI 0.53 to 0.92; 3883 participants; 13 studies, low certainty evidence), and probably reduce unplanned visits to hospitals or primary care from 26% to 21% at 6 to 9 months (OR 0.74, 95% CI 0.60 to 0.90; 3490 participants; 5 studies, moderate certainty evidence). Self-management interventions probably reduce the number of days of restricted activity by just under half a day over a two-week period (MD 0.38 days 95% CI -0.41 to -0.18; 1852 participants; 3 studies, moderate certainty evidence). Effects of interventions on school absence are uncertain due to the variation between the results of the studies (MD 0.4 fewer school days missed per year with self-management (-1.25 to 0.45; 4609 participants; 10 studies, low certainty evidence). Evidence is insufficient to show whether the requirement for reliever medications is affected by these interventions (OR 0.52, 95% CI 0.15 to 1.81; 437 participants; 2 studies; very low-certainty evidence). Self-management interventions probably improve children's asthma-related quality of life by a small amount (MD 0.36 units higher on the Paediatric AQLQ(95% CI 0.06 to 0.64; 2587 participants; 7 studies, moderate certainty evidence). AUTHORS' CONCLUSIONS: School-based asthma self-management interventions probably reduce hospital admission and may slightly reduce ED attendance, although their impact on school attendance could not be measured reliably. They may also reduce the number of days where children experience asthma symptoms, and probably lead to small improvements in asthma-related quality of life. Many of the studies tested the intervention in younger children from socially disadvantaged populations. Interventions that had a theoretical framework, engaged parents and were run outside of children's free time were associated with successful implementation.NIHR CLAHRC North Thames, UK

    Angoff anchor statements: setting a flawed gold standard?

    Get PDF
    http://www.mededpublish.org/manuscripts/120

    Biological effects of soft denture reline materials on L929 cells in vitro.

    Get PDF
    Soft denture reline materials have been developed to help patients when their oral mucosa is damaged or affected due to ill-fitting dentures or post-implant surgery. Although reports have indicated that these materials leach monomers and other components that do affect their biocompatibility, there is little information on what cell molecules may be implicated in these material/tissue interactions. The biocompatibility of six soft liners (Ufi Gel P, Sofreliner S, Durabase Soft, Trusoft, Softone and Coe Comfort) was evaluated using a mouse fibroblast cell line, L929. Within 2 h of material disc preparation, each of the materials was exposed by direct contact to L929 cells for periods of 24 and 48 h. The effect of this interaction was assessed by alamarBlue assay (for cell survival). The expression of integrin α5β1 and transforming growth factor β1 was also assessed using plate assays such as enzyme-linked immunosorbent assay. Trusoft, Softone and Coe Comfort showed significantly reduced cell survival compared with the other soft lining materials at each incubation period. Furthermore, there were significant differences with these same materials in the expression of both integrin α5β1 and transforming growth factor β1. Soft liner materials may affect cell viability and cellular proteins that have important roles in wound healing and the preservation of cell viability and function in the presence of environmental challenges and stresses

    LHC Predictions from a Tevatron Anomaly in the Top Quark Forward-Backward Asymmetry

    Get PDF
    We examine the implications of the recent CDF measurement of the top-quark forward-backward asymmetry, focusing on a scenario with a new color octet vector boson at 1-3 TeV. We study several models, as well as a general effective field theory, and determine the parameter space which provides the best simultaneous fit to the CDF asymmetry, the Tevatron top pair production cross section, and the exclusion regions from LHC dijet resonance and contact interaction searches. Flavor constraints on these models are more subtle and less severe than the literature indicates. We find a large region of allowed parameter space at high axigluon mass and a smaller region at low mass; we match the latter to an SU(3)xSU(3)/SU(3) coset model with a heavy vector-like fermion. Our scenario produces discoverable effects at the LHC with only 1-2 inverse femtobarns of luminosity at 7-8 TeV. Lastly, we point out that a Tevatron measurement of the b-quark forward-backward asymmetry would be very helpful in characterizing the physics underlying the top-quark asymmetry.Comment: 35 pages, 10 figures, 4 table

    Ordering disorder: The making of world politics

    Get PDF
    This is the final version. Available on open access from Cambridge University Press via the DOI in this recordThis article offers insights into the character and composition of world order. It does so by focusing on how world order is made and revealed through seemingly disorderly events. We examine how societies struggle to interpret and respond to disorderly events through three modes of treatment: tragedy, crisis and scandal. These, we argue, are the dominant modes of treatment in world politics, through which an account of disorder is articulated and particular political responses are mobilised. Specifically, we argue that each mode provides a particular way of problematising disorder, locating responsibility, and generating political responses. As we will demonstrate, these modes instigate the ordering of disorder, but they also agitate and reveal the contours of order itself. We argue therefore that an attentiveness to how we make sense of and respond to disorder offers the discipline new opportunities for interrogating the underlying forces, dynamics and structures that define contemporary world politics

    Collider Phenomenology with Split-UED

    Get PDF
    We investigate the collider implications of Split Universal Extra Dimensions. The non-vanishing fermion mass in the bulk, which is consistent with the KK-parity, largely modifies the phenomenology of Minimal Universal Exta Dimensions. We scrutinize the behavior of couplings and study the discovery reach of the Tevatron and the LHC for level-2 Kaluza-Klein modes in the dilepton channel, which would indicates the presence of the extra dimensions. Observation of large event rates for dilepton resonances can result from a nontrivial fermion mass profile along the extra dimensions, which, in turn, may corroborate extra dimensional explanation for the observation of the positron excess in cosmic rays.Comment: 23 pages, 15 figure

    Illness perceptions and explanatory models of viral hepatitis B & C among immigrants and refugees: a narrative systematic review.

    Get PDF
    © 2015 Owiti et al.; licensee BioMed Central. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.BACKGROUND: Hepatitis B and C (HBV, HCV) infections are associated with high morbidity and mortality. Many countries with traditionally low prevalence (such as UK) are now planning interventions (screening, vaccination, and treatment) of high-risk immigrants from countries with high prevalence. This review aimed to synthesise the evidence on immigrants' knowledge of HBV and HCV that might influence the uptake of clinical interventions. The review was also used to inform the design and successful delivery of a randomised controlled trial of targeted screening and treatment. METHODS: Five databases (PubMed, CINHAL, SOCIOFILE, PsycINFO & Web of Science) were systematically searched, supplemented by reference tracking, searches of selected journals, and of relevant websites. We aimed to identify qualitative and quantitative studies that investigated knowledge of HBV and HCV among immigrants from high endemic areas to low endemic areas. Evidence, extracted according to a conceptual framework of Kleinman's explanatory model, was subjected to narrative synthesis. We adapted the PEN-3 model to categorise and analyse themes, and recommend strategies for interventions to influence help-seeking behaviour. RESULTS: We identified 51 publications including quantitative (n = 39), qualitative (n = 11), and mixed methods (n = 1) designs. Most of the quantitative studies included small samples and had heterogeneous methods and outcomes. The studies mainly concentrated on hepatitis B and ethnic groups of South East Asian immigrants residing in USA, Canada, and Australia. Many immigrants lacked adequate knowledge of aetiology, symptoms, transmission risk factors, prevention strategies, and treatment, of hepatitis HBV and HCV. Ethnicity, gender, better education, higher income, and English proficiency influenced variations in levels and forms of knowledge. CONCLUSION: Immigrants are vulnerable to HBV and HCV, and risk life-threatening complications from these infections because of poor knowledge and help-seeking behaviour. Primary studies in this area are extremely diverse and of variable quality precluding meta-analysis. Further research is needed outside North America and Australia
    corecore