6,169 research outputs found

    Self-dual formulations of d=3 gravity theories in the path-integral framework

    Full text link
    We study the connection, at the quantum level, between d=2+1 dimensional self-dual models with actions of growing (from first to fourth) order, governing the dynamics of helicity +2 (or -2) massive excitations. We obtain identities between generating functionals of the different models using the path-integral framework, this allowing to establish dual maps among relevant vacuum expectation values. We check consistency of these v.e.v.'s with the gauge invariance gained in each mapping.Comment: 26 pages. LaTeX. Minor changes. Published in Int. J Modern Phys. A; http://www.worldscinet.com/ijmp

    Effect of the number of vortices on the torque scaling in Taylor-Couette flow

    Full text link
    Torque measurements in Taylor-Couette flow, with large radius ratio and large aspect ratio, over a range of velocities up to a Reynolds number of 24 000 are presented. Following a specific procedure, nine states with distinct number of vortices along the axis were found and the aspect ratio of the vortices were measured. The relationship between the speed and the torque for a given number of vortices is reported. In the turbulent Taylor vortex flow regime, at relatively high Reynolds number, a change in behaviour is observed corresponding to intersections of the torque-speed curves for different states. Before each intersection, the torque for a state with larger number of vortices is higher. After each intersection, the torque for a state with larger number of vortices is lower. The exponent, from the scaling laws of the torque, always depends on the aspect ratio of the vortices. When the Reynolds number is rescaled using the mean aspect ratio of the vortices, only a partial collapse of the exponent data is found.Comment: 11 pages, 6 figure

    Joint Density-Functional Theory of the Electrode-Electrolyte Interface: Application to Fixed Electrode Potentials, Interfacial Capacitances, and Potentials of Zero Charge

    Full text link
    This work explores the use of joint density-functional theory, a new form of density-functional theory for the ab initio description of electronic systems in thermodynamic equilibrium with a liquid environment, to describe electrochemical systems. After reviewing the physics of the underlying fundamental electrochemical concepts, we identify the mapping between commonly measured electrochemical observables and microscopically computable quantities within an, in principle, exact theoretical framework. We then introduce a simple, computationally efficient approximate functional which we find to be quite successful in capturing a priori basic electrochemical phenomena, including the capacitive Stern and diffusive Gouy-Chapman regions in the electrochemical double layer, quantitative values for interfacial capacitance, and electrochemical potentials of zero charge for a series of metals. We explore surface charging with applied potential and are able to place our ab initio results directly on the scale associated with the Standard Hydrogen Electrode (SHE). Finally, we provide explicit details for implementation within standard density-functional theory software packages at negligible computational cost over standard calculations carried out within vacuum environments.Comment: 18 pages, 5 figures. Initially presented at APS March Meeting 2010. Accepted for publication in Physical Review B on Jul. 27, 201

    Sistemes públics i privats de previsió

    Get PDF
    The Welfare State is deeply embedded in European culture and it is difficult to disinvent what has already been invented. However an equilibrium must be maintained between income and payments. Special taxes will be needed to sustain a reasonable welfare system. It is also difficult to justify current expenditures and there is wide scope for the rationalisation of consumption and the reduction of fraud. Pensions should be more related to actual payments made. Private pension schemes are necessary to complement the public system. These private pension schemes should be market based. Both public and private systems require freedom of information, so that future beneficiaries always know exactly where they stand

    Geysers in the Lagoon: new Herbig-Haro objects in M8

    Get PDF
    Aims: We search for direct evidence of ongoing star formation by accretion in the Lagoon Nebula (M8), using optical wide-field narrow-band imaging obtained at La Silla Observatory. Methods: We examine [SII] and Halpha images for line-emission features that could be interpreted as signatures of outflow activity of the exciting sources. Results: We discover five new Herbig-Haro objects, study in detail their morphology and attempt to identify their potential driving sources among the population of T Tauri stars and embedded sources in the surroundings. Conclusions: The results reported here conclusively demonstrate the existence of very young stars going through the accreting phase in the M8 region.Comment: 9 pages, 6 postscript figures (one in color). Accepted, Astronomy and Astrophysic

    Les associacions en els òrgans municipals de Participació Ciutadana de Burjassot

    Get PDF
    This article attempts to present some of the results obtained throughout the study entitled “The perception of civil participation and its ability to influence local government: the case of Burjassot”, which is the Final Course Work for the Master in Management and Promotion of Local Development. This piece of research was carried out by applying quantitative techniques (documentary and statistical analysis) and qualitative methods (interviews, panel of experts). We specifically focus here on collecting the results involving the role played by partnerships at Burjassot’s Municipal Bodies for Civil Participation. We analyze their participation, the representativeness contributed to the Municipal Civil Participation Council by them, we offer suggestions for improvement received from persons interviewed and point out the virtues and dangers of representative participation as well as strategies for reducing the latter. In short, an attempt is made to both improve the participatory process in Burjassot as in many other places which chose a similar model

    Sistemes públics i privats de previsió

    Get PDF
    The Welfare State is deeply embedded in European culture and it is difficult to disinvent what has already been invented. However an equilibrium must be maintained between income and payments. Special taxes will be needed to sustain a reasonable welfare system. It is also difficult to justify current expenditures and there is wide scope for the rationalisation of consumption and the reduction of fraud. Pensions should be more related to actual payments made. Private pension schemes are necessary to complement the public system. These private pension schemes should be market based. Both public and private systems require freedom of information, so that future beneficiaries always know exactly where they stand
    corecore