45 research outputs found

    Pressure to order g8∗log(g)g^8*log(g) in ϕ4\phi^4-theory at weak coupling

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    We calculate the pressure of massless ϕ4\phi^4-theory to order g8log⁥(g)g^8\log(g) at weak coupling. The contributions to the pressure arise from the hard momentum scale of order TT and the soft momentum scale of order gTgT. Effective field theory methods and dimensional reduction are used to separate the contributions from the two momentum scales: The hard contribution can be calculated as a power series in g2g^2 using naive perturbation theory with bare propagators. The soft contribution can be calculated using an effective theory in three dimensions, whose coefficients are power series in g2g^2. This contribution is a power series in gg starting at order g3g^3. The calculation of the hard part to order g6g^6 involves a complicated four-loop sum-integral that was recently calculated by Gynther, Laine, Schr\"oder, Torrero, and Vuorinen. The calculation of the soft part requires calculating the mass parameter in the effective theory to order g6g^6 and the evaluation of five-loop vacuum diagrams in three dimensions. This gives the free energy correct up to order g7g^7. The coefficients of the effective theory satisfy a set of renormalization group equations that can be used to sum up leading and subleading logarithms of T/gTT/gT. We use the solutions to these equations to obtain a result for the free energy which is correct to order g8log⁥(g)g^8\log(g). Finally, we investigate the convergence of the perturbative series.Comment: 29 pages and 12 figs. New version: we have pushed the calculations to g^8*log(g) using the renormalization group to sum up log(g) from higher orders. Published in JHE

    Three-loop HTL QCD thermodynamics

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    The hard-thermal-loop perturbation theory (HTLpt) framework is used to calculate the thermodynamic functions of a quark-gluon plasma to three-loop order. This is the highest order accessible by finite temperature perturbation theory applied to a non-Abelian gauge theory before the high-temperature infrared catastrophe. All ultraviolet divergences are eliminated by renormalization of the vacuum, the HTL mass parameters, and the strong coupling constant. After choosing a prescription for the mass parameters, the three-loop results for the pressure and trace anomaly are found to be in very good agreement with recent lattice data down to T∌2−3 TcT \sim 2-3\,T_c, which are temperatures accessible by current and forthcoming heavy-ion collision experiments.Comment: 27 pages, 11 figures; corresponds with published version in JHE

    Developing understanding of pupil feedback using Habermas’ notion of communicative action

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    The focus of this article is to explore the notion of pupil feedback and the possible ways in which it can be understood and developed using JĂŒrgen Habermas’ theory of Communicative Action. The theoretical position adopted is framed within the concept of assessment for learning, and is particularly related to the notion of assessment as learning within AfL. Furthermore, the paper is located within a social constructivist perspective. JĂŒrgen Habermas’ theory of Communicative Action enables us to recognise that feedback, and more importantly the interpretation of feedback, cannot be a one-way process. Without recognition of pupil interpretation, its very purpose (to alter the learning gap) is compromised. This paper offers new ways of exploring feedback, which recognise complexity and the importance of interpretation and relationships in shared negotiated communicative contexts. It further contributes to the ways in which assessment and learning are understood and intersect

    Associations between general self-efficacy and health-related quality of life among 12-13-year-old school children: a cross-sectional survey

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    <p>Abstract</p> <p>Background</p> <p>While research on school children's health has mainly focused on risk factors and illness, few studies have examined aspects of health promotion. Thus, this study focuses on health promotional factors including general self-efficacy (GSE) and health-related quality of life (HRQOL). GSE refers to a global confidence in coping ability across a wide range of demanding situations, and is related to health. The purpose of this study was to examine associations between GSE and HRQOL, and associations between HRQOL and socio-demographic characteristics. Knowledge of these associations in healthy school children is currently lacking.</p> <p>Methods</p> <p>During 2006 and 2007, 279 school children in the seventh grade across eastern Norway completed a survey assessing their GSE and HRQOL. The children were from schools that had been randomly selected using cluster sampling. T-tests were computed to compare mean subscale values between HRQOL and socio-demographic variables. Single and multiple regression analyses were performed to explore associations among GSE, HRQOL and socio-demographic variables.</p> <p>Results</p> <p>Regression analyses showed a significant relationship between increasing degrees of GSE and increasing degrees of HRQOL. In analyses adjusted for socio-demographic variables, boys scored higher than girls on self-esteem. School children from single-parent families had lower scores on HRQOL than those from two-parent families, and children who had relocated within the last five years had lower scores on HRQOL than those who had not relocated.</p> <p>Conclusion</p> <p>The strong relationship between GSE and HRQOL indicates that GSE might be a resource for increasing the HRQOL for school children.</p

    Mindful Aging: The Effects of Regular Brief Mindfulness Practice on Electrophysiological Markers of Cognitive and Affective Processing in Older Adults

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    There is growing interest in the potential benefits of mindfulness meditation practices in terms of counteracting some of the cognitive effects associated with aging. Pursuing this question, the aim of the present study was to investigate the influence of mindfulness training on executive control and emotion regulation in older adults, by means of studying behavioral and electrophysiological changes. Participants, 55 to 75 years of age, were randomly allocated to an 8-week mindful breath awareness training group or an active control group engaging in brain training exercises. Before and after the training period, participants completed an emotional-counting Stroop task, designed to measure attentional control and emotion regulation processes. Concurrently, their brain activity was measured by means of 64-channel electroencephalography. The results show that engaging in just over 10 min of mindfulness practice five times per week resulted in significant improvements in behavioral (response latency) and electrophysiological (N2 event-related potential) measures related to general task performance. Analyses of the underlying cortical sources (Variable Resolution Electromagnetic Tomography, VARETA) indicate that this N2-related effect is primarily associated with changes in the right angular gyrus and other areas of the dorsal attention network. However, the study did not find the expected specific improvements in executive control and emotion regulation, which may be due to the training instructions or the relative brevity of the intervention. Overall, the results indicate that engaging in mindfulness meditation training improves the maintenance of goal-directed visuospatial attention and may be a useful strategy for counteracting cognitive decline associated with aging

    INSPIRE study: does stress management improve the course of inflammatory bowel disease and disease-specific quality of life in distressed patients with ulcerative colitis or Crohn's disease? A randomized controlled trial.

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    BACKGROUND: The use of stress management psychotherapy is hypothesized to produce greater improvement in disease course and disease-specific quality of life (IBDQ) compared to usual medical care alone in patients with ulcerative colitis (UC) or Crohn's disease (CD) showing high levels of stress (based on the Perceived Stress Questionnaire [PSQ]). METHODS: Fifty-eight patients with UC and 56 patients with CD who had experienced continuous disease activity or had relapsed over the previous 18 months, with an activity index for UC or CD ≄ 4, a PSQ ≄ 60, and without serious psychiatric disorders or other serious medical conditions were randomized to receive either treatment as usual (TAU) or TAU plus stress management psychotherapy. Psychotherapy consisted of three group sessions (psychoeducation, problem-solving, relaxation) and 6-9 individual sessions based on cognitive behavior therapy-related methods with 1-3 booster sessions at 6 and 12 months follow-up. Gastroenterologists blinded to intervention group assessed disease activity and course at baseline and at 3, 6, 12, and 18 months. Patients completed the IBDQ at baseline, 6, 12, and 18 months. RESULTS: The intervention did not improve disease or reduce relapse; however, it increased the IBDQ score (P = 0.009, mean differences 16.3 [SD 6.1]). On analysis of UC and CD separately, improvement of IBDQ was only found in the UC group. CONCLUSIONS: Stress management psychotherapy does not appear to improve disease course or reduce relapse in patients with IBD. It might improve quality of life, particularly in patients with UC
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