1,825 research outputs found

    Stochastic quantization of Yang-Mills field theory: Gauge-fixing parameter dependence and equilibrium limit

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    We calculate, in the framework of stochastic quantization, the one-loop-divergent part of the gluon self-energy and the triple-gluon vertex of pure Yang Mills field theory, with an arbitrary choice of the stochastic gauge-fixing parameter. This allows us to check that the strong conditions imposed by renormalizability are satisfied up to one-loop order. We compare our results with those corning from the Faddeev Popov theory and discuss the relationship between both approaches in the equilibrium limit

    Matching microscopic and macroscopic responses in glasses

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    We first reproduce on the Janus and Janus II computers a milestone experiment that measures the spinglass coherence length through the lowering of free-energy barriers induced by the Zeeman effect. Secondly, we determine the scaling behavior that allows a quantitative analysis of a new experiment reported in the companion Letter [S. Guchhait and R. Orbach, Phys. Rev. Lett. 118, 157203 (2017)]. The value of the coherence length estimated through the analysis of microscopic correlation functions turns out to be quantitatively consistent with its measurement through macroscopic response functions. Further, nonlinear susceptibilities, recently measured in glass-forming liquids, scale as powers of the same microscopic length

    A statics-dynamics equivalence through the fluctuation-dissipation ratio provides a window into the spin-glass phase from nonequilibrium measurements

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    We have performed a very accurate computation of the non-equilibrium fluctuation- dissipation ratio for the 3D Edwards-Anderson Ising spin glass, by means of large-scale simulations on the special-purpose computers Janus and Janus II. This ratio (computed for finite times on very large, effectively infinite, systems) is compared with the equilibrium probability distribution of the spin overlap for finite sizes. Our main result is a quantitative statics-dynamics dictionary, which could allow the experimental exploration of important features of the spin-glass phase without requiring uncontrollable extrapolations to infinite times or system sizes

    Nature of the spin-glass phase at experimental length scales

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    We present a massive equilibrium simulation of the three-dimensional Ising spin glass at low temperatures. The Janus special-purpose computer has allowed us to equilibrate, using parallel tempering, L = 32 lattices down to T ≈ 0.64Tc. We demonstrate the relevance of equilibrium finite-size simulations to understand experimental non-equilibrium spin glasses in the thermodynamical limit by establishing a time-length dictionary. We conclude that non-equilibrium experiments performed on a time scale of one hour can be matched with equilibrium results on L ≈ 110 lattices. A detailed investigation of the probability distribution functions of the spin and link overlap, as well as of their correlation functions, shows that Replica Symmetry Breaking is the appropriate theoretical framework for the physically relevant length scales. Besides, we improve over existing methodologies to ensure equilibration in parallel tempering simulations

    La importancia de las interrelaciones primarias en el deporte

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    En el presente trabajo centramos la investigación sobre la relevancia que poseen las relaciones primarias en la configuración del deporte y su relación con las diferentes disciplinas deportivas. Se realiza un estudio longitudinal sobre las principales formas de relación primaria en el deporte; individual, familia, amigos, compañeros de estudio o trabajo y su relación con elementos objetivos y subjetivos del deporte. Para la extracción de datos se ha recurrido a los barómetros de opinión y encuestas específicas sobre el deporte realizadas por el CIS entre los años 1997 y 2014. Las técnicas utilizadas son: el análisis de frecuencias para el estudio longitudinal de las relaciones sociales en el deporte; el análisis factorial exploratorio (EFA) para agrupar las distintas disciplinas deportivas y el análisis de regresión logarítmica para identificar las variables sociodemográficas y factores que aportan mayor poder explicativo sobre las principales categorías de estudio. Como resultados principales se muestra que ha aumentado la práctica del ejercicio físico y el deporte de manera individual y en familia mediante formas de organización no asociativas o federativas. El deporte supone un importante recurso relacional en nuestros días donde los individuos dan respuesta a necesidades de socialización, favoreciendo relaciones micro-grupales que se estructuran alrededor de distintos grados de soportes normativos.In this paper we focus on research on the relevance of primary relationships in the configuration of sport and its relationship with different sports disciplines. A longitudinal study of the main forms of primary relations in sport has been carried out, demonstrating the interrelationship of the objective and subjective elements involved in taking part in sporting activity. This study is based on opinion surveys and specific studies relating to sport carried out by the CIS statistical institute from 1995 to 2014. The techniques used include: frequency analysis in the longitudinal study of social relations in sport; the exploratory factor analysis (EFA), and the logarithm regression analysis to identify the sociodemographic variables and factors that contribute more explanatory power on the main categories of study. The main results show that it has increased the practice of physical exercise and sport in an individual and family way through non-associative or federative forms of organization. Sport is an important inter-relational resource in contemporary society, where individuals also meet their needs for socialization, fostering micro-group relations structured around different degrees of normative supports. Sport provides people with a balanced outlet for their emotions, fostering an ideal environment for developing primary relations based on affection, empathy and trust

    A statics-dynamics equivalence through the fluctuation-dissipation ratio provides a window into the spin-glass phase from nonequilibrium measurements

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    The unifying feature of glass formers (such as polymers, supercooled liquids, colloids, granulars, spin glasses, superconductors, ...) is a sluggish dynamics at low temperatures. Indeed, their dynamics is so slow that thermal equilibrium is never reached in macroscopic samples: in analogy with living beings, glasses are said to age. Here, we show how to relate experimentally relevant quantities with the experimentally unreachable low-temperature equilibrium phase. We have performed a very accurate computation of the non-equilibrium fluctuation-dissipation ratio for the three-dimensional Edwards-Anderson Ising spin glass, by means of large-scale simulations on the special-purpose computers Janus and Janus II. This ratio (computed for finite times on very large, effectively infinite, systems) is compared with the equilibrium probability distribution of the spin overlap for finite sizes. The resulting quantitative statics-dynamics dictionary, based on observables that can be measured with current experimental methods, could allow the experimental exploration of important features of the spin-glass phase without uncontrollable extrapolations to infinite times or system sizes

    Characterization of wind-blown sediment transport with height in a highly mobile dune (SW Spain)

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    The Valdevaqueros dune is located at one of the windiest points of Europe, where the frequent occurrence of strong easterly winds has generated a highly mobile dune. Several rotating cup anemometers in vertical array and a self-designed vertical sand trap, were placed to retain the drift sands at different heights over the surface in order to determine theoretical and actual sand transport rates in the Valdevaqueros dune system. General results show that 90% of the wind-blown sand is transported within the first 20cm above the dune crest surface. Theoretical transport rates based on different empirical formulae were 0.33 to 0.78 times the in-situ sand transport rate detected, which was 2.08·10-2kgm-1s-1 under moderate wind power (mean speed ranging from 8.4 to 17.9ms-1). Analysis of different statistical grain-size parameters helped to understand sand transport distribution at different heights

    Mechanical Performance of Concrete Made with the Addition of Recycled Macro Plastic Fibres

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    For many decades, researchers have been working on finding innovative and sustainable solutions to address the enormous quantities of plastic waste that are produced every year which, after being collected, are transformed into energy, recycled, or sent to landfills. Giving a second life to plastic waste as a material to be incorporated, in the form of macro-fibres, into concrete, could be one such solution. The purpose of this study was to analyse the mechanical and physical behaviour of the hardened concrete reinforced with macro plastic fibres (RPFs) obtained from food packaging waste (FPW) discarded during the packaging phase. By varying the quantity of macro-fibres used, physical and mechanical properties such as compressive strength, modulus of elasticity, flexural strength, and toughness were evaluated. It was observed that, although the presence of macro plastic fibres reduced the mechanical resistance capacity compared to that of traditional concrete, their contribution proved to be of some importance in terms of toughness, bringing an improvement in the post-crack resistance of the composite material. This innovative mixture provides a further impulse to the circular economy

    Influence of Di erent Sieving Methods on Estimation of Sand Size Parameters

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    Sieving is one of the most used operational methods to determine sand size parameters which are essential to analyze coastal dynamics. However, the influence of hand versus mechanical shaking methods has not yet been studied. Herein, samples were taken from inside the hopper of a trailing suction dredger and sieved by hand with sieves of 10 and 20 cm diameters on board the dredger. Afterwards, these same samples were sieved with a mechanical shaker in the laboratory on land. The results showed di erences for the main size parameters D50, standard deviation, skewness, and kurtosis. Amongst the main results, it should be noted that the highest values for D50 and kurtosis were given by the small sieves method. On the other hand, the lowest values were given by the mechanical shaker method in the laboratory. Furthermore, standard deviation and skewness did not seem to be a ected by the sieving method which means that all the grainsize distribution was shifted but the shape remained unchanged. The few samples that do not follow these patterns have a higher percentage of shells. Finally and definitely, the small sieves should be rejected as a sieving method aboard

    Main specifications of CFD codes for WUIVIEW activities

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    CFD simulations will be the core activity of the WUVIEW performance based fire safety analysis. The purpose of this document is to provide WUIVIEW partners with a general overview of the CFD codes to be used in the Action. The general simulation framework is described, particularly highlighting data inputs and scenario description requirements, to be developed in subsequent WUIVIEW WPs. This TN provides the technical foundations and main specifications of the databases to be designed within the WUIVIEW working program (ongoing action by UPC).Postprint (updated version
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