153,210 research outputs found

    SU(2) potentials in quantum gravity

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    We present investigations of the potential between static charges from a simulation of quantum gravity coupled to an SU(2) gauge field on 63×46^{3}\times 4 and 83×48^{3}\times 4 simplicial lattices. In the well-defined phase of the gravity sector where geometrical expectation values are stable, we study the correlations of Polyakov loops and extract the corresponding potentials between a source and sink separated by a distance RR. In the confined phase, the potential has a linear form while in the deconfined phase, a screened Coulombic behavior is found. Our results indicate that quantum gravitational effects do not destroy confinement due to non-abelian gauge fields.Comment: 3 pages, contribution to Lattice 94 conference, uuencoded compressed postscript fil

    Lagrangian one-particle velocity statistics in a turbulent flow

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    We present Lagrangian one-particle statistics from the Risoe PTV experiment of a turbulent flow. We estimate the Lagrangian Kolmogorov constant C0C_0 and find that it is affected by the large scale inhomogeneities of the flow. The pdf of temporal velocity increments are highly non-Gaussian for small times which we interpret as a consequence of intermittency. Using Extended Self-Similarity we manage to quantify the intermittency and find that the deviations from Kolmogorov 1941 similarity scaling is larger in the Lagrangian framework than in the Eulerian. Through the multifractal model we calculate the multifractal dimension spectrum.Comment: 22 pages, 14 figure

    Ideal Theory and "Ought Implies Can"

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    When we can’t live up to the ultimate standards of morality, how can moral theory give us guidance? We can distinguish between ideal and non-ideal theory to see that there are different versions of the voluntarist constraint, ‘ought implies can.’ Ideal moral theory identifies the best standard, so its demands are constrained by one version. Non-ideal theory tells us what to do given our psychological and motivational shortcomings and so is constrained by others. Moral theory can now both provide an ultimate standard and give us guidance; this view also gives us new insights into demandingness and blame

    Down-to-earth economy: the discursive contribution of sustainable consumption and production debate

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    Sustainable consumption and production (SCP) is a topical concept as national SCP programmes have been drafted by several countries around Europe. This discourse analysis, based on interviews with Finnish SCP committee members, suggests that sustainable consumption and production can be a useful concept for approaching economy in a down-to-earth manner. It can enrich the environmental policy agenda that has long been dominated by technology-oriented ecological modernization. A critical point is, however, that the SCP depate is more concentrated on the needs of consumers than on the needs of poor, the initial focus of sustainable development. Moreover,ideas on how to really change consumption patterns seem to be scarce, scattered, and also contradictory among the SCP stakeholders

    Fibonacci numbers and orthogonal polynomials

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    We prove that the sequence (1/Fn+2)n≥0(1/F_{n+2})_{n\ge 0} of reciprocals of the Fibonacci numbers is a moment sequence of a certain discrete probability, and we identify the orthogonal polynomials as little qq-Jacobi polynomials with q=(1−5)/(1+5)q=(1-\sqrt{5})/(1+\sqrt{5}). We prove that the corresponding kernel polynomials have integer coefficients, and from this we deduce that the inverse of the corresponding Hankel matrices (1/Fi+j+2)(1/F_{i+j+2}) have integer entries. We prove analogous results for the Hilbert matrices.Comment: A note dated June 2007 has been added with some historical comments. Some references have been added and complete

    The ladder crystal

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    n this paper I introduce a new description of the crystal B(Λ0)B(\Lambda_0) of slℓ^\hat{\mathfrak{sl}_\ell}. As in the Misra-Miwa model of B(Λ0)B(\Lambda_0), the nodes of this crystal are indexed by partitions and the ii-arrows correspond to adding a box of residue ii. I then show that the two models are equivalent by interpreting the operation of regularization introduced by James as a crystal isomorphism
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