24,029 research outputs found

    Three-loop HTLpt thermodynamics at finite temperature and chemical potential

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    In this proceedings we present a state-of-the-art method of calculating thermodynamic potential at finite temperature and finite chemical potential, using Hard Thermal Loop perturbation theory (HTLpt) up to next-to-next-leading-order (NNLO). The resulting thermodynamic potential enables us to evaluate different thermodynamic quantities including pressure and various quark number susceptibilities (QNS). Comparison between our analytic results for those thermodynamic quantities with the available lattice data shows a good agreement.Comment: 5 pages, 6 figures, conference proceedings of XXI DAE-BRNS HEP Symposium, IIT Guwahati, December 2014; to appear in 'Springer Proceedings in Physics Series

    Coulomb Drag of Massless Fermions in Graphene

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    Using a novel structure, consisting of two, independently contacted graphene single layers separated by an ultra-thin dielectric, we experimentally measure the Coulomb drag of massless fermions in graphene. At temperatures higher than 50 K, the Coulomb drag follows a temperature and carrier density dependence consistent with the Fermi liquid regime. As the temperature is reduced, the Coulomb drag exhibits giant fluctuations with an increasing amplitude, thanks to the interplay between coherent transport in the graphene layer and interaction between the two layers.Comment: 5 pages, 5 figure

    Three-loop HTL gluon thermodynamics at intermediate coupling

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    We calculate the thermodynamic functions of pure-glue QCD to three-loop order using the hard-thermal-loop perturbation theory (HTLpt) reorganization of finite temperature quantum field theory. We show that at three-loop order hard-thermal-loop perturbation theory is compatible with lattice results for the pressure, energy density, and entropy down to temperatures T3  TcT\simeq3\;T_c. Our results suggest that HTLpt provides a systematic framework that can used to calculate static and dynamic quantities for temperatures relevant at LHC.Comment: 24 pages, 13 figs. 2nd version: improved discussion and fixing typos. Published in JHE

    Treehoppers (Hemiptera: Aetalionidae and Membracidae) from Madre de Dios region, Peru

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    A list of treehoppers (Aetalionidae and Membracidae) is presented from Madre de Dios region at the southeastern Amazon basin in Peru. The treehopper specimens were collected as by-catch in a survey of the beetles in the Villa Carmen Biological Station and Los Amigos Biological Station. The list comprises 44 species, 31 genera, 16 tribes and 9 subfamilies. Ten genera are new records to Peru. The images of representative specimens of each identified species and genera are provided to facilitate the identification of the local treehopper fauna. Resumen: Se presenta una lista de los membrácidos (Aetalionidae y Membracidae) de la región Madre de Dios, en el sureste de la cuenca Amazónica, en Perú. La lista está basada en especímenes recolectados como captura fortuita en un inventario de escarabajos en las estaciones biológicas Villa Carmen y Los Amigos. La lista incluye 44 especies, 31 géneros, 16 tribus y 9 subfamilias. Diez géneros son nuevos registros para Perú. Se presentan las imágenes de especímenes representativos de cada especie y género para facilitar la identifición de la fauna local de los membrácidos

    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 T23TcT \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

    Group treatments for sensitive health care problems : a randomised controlled trial of group versus individual physiotherapy sessions for female urinary incontinence

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    Background: The aim was to compare effectiveness of group versus individual sessions of physiotherapy in terms of symptoms, quality of life, and costs, and to investigate the effect of patient preference on uptake and outcome of treatment. Methods: A pragmatic, multi-centre randomised controlled trial in five British National Health Service physiotherapy departments. 174 women with stress and/or urge incontinence were randomised to receive treatment from a physiotherapist delivered in a group or individual setting over three weekly sessions. Outcome were measured as Symptom Severity Index; Incontinence-related Quality of Life questionnaire; National Health Service costs, and out of pocket expenses. Results: The majority of women expressed no preference (55%) or preference for individual treatment (36%). Treatment attendance was good, with similar attendance with both service delivery models. Overall, there were no statistically significant differences in symptom severity or quality of life outcomes between the models. Over 85% of women reported a subjective benefit of treatment, with a slightly higher rating in the individual compared with the group setting. When all health care costs were considered, average cost per patient was lower for group sessions (Mean cost difference £52.91 95%, confidence interval (£25.82 - £80.00)). Conclusion: Indications are that whilst some women may have an initial preference for individual treatment, there are no substantial differences in the symptom, quality of life outcomes or non-attendance. Because of the significant difference in mean cost, group treatment is recommended

    Note on Moufang-Noether currents

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    The derivative Noether currents generated by continuous Moufang tranformations are constructed and their equal-time commutators are found. The corresponding charge algebra turns out to be a birepresentation of the tangent Mal'ltsev algebra of an analytic Moufang loop.Comment: LaTeX2e, 6 pages, no figures, presented on "The XVth International Colloquium on Integrable Systems and Quantum Symmetries, Prague, 15-17 June, 2006

    Improving Monolithic Perovskite Silicon Tandem Solar Cells From an Optical Viewpoint

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    Perovskite silicon tandem solar cells are the most promising concept for a future photovoltaic technology. We report on recent progress from an optical viewpoint and disucss how we achieved more than 25 device efficienc
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