33,058 research outputs found

    X-Type Interface for Management of Multidomain Multitechnology Networks

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    The specification and implementation of Xcoop interfaces has received great attention in the last few years. In fact, the appropriate design of this system component is a key aspect for efficient and seamless co-operative management. In this context it is worth mentioning the EURESCOM P408 project and the standards of the European Telecommunication Standards Institute (ETSI) in Europe and the ITU-T and Telemanagement Forum related work worldwide. The Xcoop specification presented in this paper, produced as part of the results of the project MISA co-funded by the Commission of the European Union, is a step ahead in the evolution of this system interface. Distinguished from preceding works, this one allows interactions between management systems independently to the underlying network technology, ATM, SDH or hybrid. This is achieved by defining appropriate functionality and an information model, indeed, where the specific characteristics of ATM and SDH resources are abstracted and merged in common classes.Peer ReviewedPostprint (published version

    Nonhyperbolic step skew-products: Ergodic approximation

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    We study transitive step skew-product maps modeled over a complete shift of kk, k2k\ge2, symbols whose fiber maps are defined on the circle and have intermingled contracting and expanding regions. These dynamics are genuinely nonhyperbolic and exhibit simultaneously ergodic measures with positive, negative, and zero exponents. We introduce a set of axioms for the fiber maps and study the dynamics of the resulting skew-product. These axioms turn out to capture the key mechanisms of the dynamics of nonhyperbolic robustly transitive maps with compact central leaves. Focusing on the nonhyperbolic ergodic measures (with zero fiber exponent) of these systems, we prove that such measures are approximated in the weak\ast topology and in entropy by hyperbolic ones. We also prove that they are in the intersection of the convex hulls of the measures with positive fiber exponent and with negative fiber exponent. Our methods also allow us to perturb hyperbolic measures. We can perturb a measure with negative exponent directly to a measure with positive exponent (and vice-versa), however we lose some amount of entropy in this process. The loss of entropy is determined by the difference between the Lyapunov exponents of the measures.Comment: 43 pages, 5 figure

    Four keys to Chilean culture : authoritarianism, legalism, fatalism and compadrazgo

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    Chilean culture is said to be part of a wider Hispanic American culture that shares many traits (see Godoy et al. 1986; Subercaseaux 1999; Valdivieso and which could be identified as an identity with a Latin American sense (see Rodríguez et al. 2001). In this sense, though it may seem as if any attempt to describe or analyse particular operating elements, processes, systems and structures were a useless task, the nature of identity makes it a multiple and symbolically contradictory phenomenon, with relevant contextual 'consequences' and particularities that help identify a collective imaginary that can be associated with what means to be Chilean. As such, the importance of meaning lies not on its production but rather on its reception; therefore, we aim to address some elements of the reception that we have identified as 'critical' or 'diagnostic'. By 'critical', we mean those elements, which absence would substantively modify what is collectively associated with Chilean culture and by 'diagnostic', we suggest the possibility they offer of exploring meaningful contextual traits. In order to contextualise our analysis, we will focus on three discursive levels, namely organisational/structural, cultural/ideological and identity. At the organisational/structural level, we will make reference to structure and aesthetics in the broader sense of social context as well as in public and private organisations; at cultural/ideological level, we will make reference to practices, rituals, values and behaviours; and at the identity level we will make reference to strategies individuals use to manage their social identities

    Climate change impacts on water for irrigated horticulture in the Vale of Evesham. Final Report

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    This project has undertaken a scoping review and assessment of the impacts of climate change on irrigated horticulture in the Vale of Evesham, an area of intense irrigated production located within the Environment Agency’s Warwickshire Avon CAMS Catchment. The research was based on a combination of methodologies including desk-based review of published and grey literature, computer agroclimatic and water balance modelling, GIS mapping, meetings with key informants and a stakeholder workshop. Future climate datasets were derived from the latest UK Climate Impacts Programme (UKICIP02) climatology, using selected emission scenarios for the 2020s, 2050s and 2080s. These scenarios were then used to model and map the future agroclimatic conditions under which agriculture might operate and the consequent impacts on irrigation need (depths of water applied) and volumetric demand. This was complimented by a postal survey to abstractors and a stakeholder workshop, to identify, review and assess farmer adaptation options and responses. The key findings arising from the research, implications for water resource management and recommendations for further work are summarised below. Using a geographical information system (GIS), a series of agroclimate maps have been produced, for the baseline and selected UKCIP02 scenario. The maps show major changes in agroclimate within the catchment over the next 50 years. The driest agroclimate zones are currently located around Worcester, Evesham, Tewkesbury and Gloucester, corresponding to areas where horticultural production and irrigation demand are most concentrated. By the 2020s, all agroclimate zones are predicted to increase in aridity. By the 2050s the entire catchment is predicted to have a drier agroclimate than is currently experienced anywhere in the driest parts of the catchment. This will have major impacts on the pattern of land use and irrigation water demand. Cont/d

    A model for the Delta(1600) resonance and gamma N -> Delta(1600) transition

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    A covariant spectator constituent quark model is applied to study the gamma N -> Delta(1600) transition. Two processes are important in the transition: a photon couples to the individual quarks of the Delta(1600) core (quark core), and a photon couples to the intermediate pion-baryon states (pion cloud). While the quark core contributions are estimated assuming Delta(1600) as the first radial excitation of Delta(1232), the pion cloud contributions are estimated based on an analogy with the gamma N -> Delta(1232) transition. To estimate the pion cloud contributions in the gamma N -> Delta(1600) transition, we include the relevant intermediate states, pi-N, pi-Delta, pi-N(1440) and pi-Delta(1600). Dependence on the four-momentum transfer squared, Q2, is predicted for the magnetic dipole transition form factor, GM*(Q2), as well as the helicity amplitudes, A_1/2(Q2) and A_3/2(Q2). The results at Q2=0 are compared with the existing data.Comment: To appear in Phys. Rev. D. Version with small modifications. 14 pages, 6 figures and 3 table

    Trace anomalies and the string-inspired definition of quantum-mechanical path integrals in curved space

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    We consider quantum-mechanical path integrals for non-linear sigma models on a circle defined by the string-inspired method of Strassler, where one considers periodic quantum fluctuations about a center-of-mass coordinate. In this approach one finds incorrect answers for the local trace anomalies of the corresponding nn-dimensional field theories in curved space. The quantum field theory approach to the quantum-mechanical path-integral, where quantum fluctuations are not periodic but vanish at the endpoints, yields the correct answers. We explain these results by a detailed analysis of general coordinate invariance in both methods. Both approaches can be derived from the same operator expression and the integrated trace anomalies in both schemes agree. In the string-inspired method the integrands are not invariant under general coordinate transformations and one is therefore not permitted to use Riemann normal coordinates.Comment: LaTeX, 12 pages, 17 figure

    Effect of the spin-orbit interaction on the thermodynamic properties of crystals: The specific heat of bismuth

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    In recent years, there has been increasing interest in the specific heat CC of insulators and semiconductors because of the availability of samples with different isotopic masses and the possibility of performing \textit{ab initio} calculations of its temperature dependence C(T)C(T) using as a starting point the electronic band structure. Most of the crystals investigated are elemental (e.g., germanium) or binary (e.g., gallium nitride) semiconductors. The initial electronic calculations were performed in the local density approximation and did not include spin-orbit interaction. Agreement between experimental and calculated results was usually found to be good, except for crystals containing heavy atoms (e.g., PbS) for which discrepancies of the order of 20% existed at the low temperature maximum found for C/T3C/T^3. It has been conjectured that this discrepancies result from the neglect of spin-orbit interaction which is large for heavy atoms (Δ0\Delta_0\sim1.3eV for the pp valence electrons of atomic lead). Here we discuss measurements and \textit{ab initio} calculations of C(T)C(T) for crystalline bismuth (Δ0\Delta_0\sim1.7 eV), strictly speaking a semimetal but in the temperature region accessible to us (T>T > 2K) acting as a semiconductor. We extend experimental data available in the literature and notice that the \textit{ab initio} calculations without spin-orbit interaction exhibit a maximum at \sim8K, about 20% lower than the measured one. Inclusion of spin-orbit interaction decreases the discrepancy markedly: The maximum of C(T)C(T) is now only 7% larger than the measured one. Exact agreement is obtained if the spin-orbit hamiltonian is reduced by a factor of \sim0.8.Comment: 4 pages, 3 figure

    Coping with Persistent Pain, Effectiveness Research into Self-management (COPERS): statistical analysis plan for a randomised controlled trial

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    This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), 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
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