6,073 research outputs found

    Non-perturbative QEG Corrections to the Yang-Mills Beta Function

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    We discuss the non-perturbative renormalization group evolution of the gauge coupling constant by using a truncated form of the functional flow equation for the effective average action of the Yang-Mills-gravity system. Our result is consistent with the conjecture that Quantum Einstein Gravity (QEG) is asymptotically safe and has a vanishing gauge coupling constant at the non-trivial fixed point.Comment: To appear in the proceedings of CORFU 200

    Growth, profits and technological choice: The case of the Lancashire cotton textile industry

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    Using Lancashire textile industry company case studies and financial records, mainly from the period just before the First World War, the processes of growth and decline are re-examined. These are considered by reference to the nature of Lancashire entrepreneurship and the impact on technological choice. Capital accumulation, associated wealth distributions and the character of Lancashire business organisation were sybiotically linked to the success of the industry before 1914. However, the legacy of that accumulation in later decades, chronic overcapacity, formed a barrier to reconstruction and enhanced the preciptious decline of a once great industry

    Quantum corrections to Higher-Dimensional Theories

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    This is a non-technical summary of the subtleties of quantum corrections on extra-dimensional theories: should one first renormalize and then mode expand, or first expand in four-dimensional modes and then renormalize?Comment: 9 pages, based on a talk at IRGAC 2006, Barcelon

    Comparison theory and smooth minimal C*-dynamics

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    We prove that the C*-algebra of a minimal diffeomorphism satisfies Blackadar's Fundamental Comparability Property for positive elements. This leads to the classification, in terms of K-theory and traces, of the isomorphism classes of countably generated Hilbert modules over such algebras, and to a similar classification for the closures of unitary orbits of self-adjoint elements. We also obtain a structure theorem for the Cuntz semigroup in this setting, and prove a conjecture of Blackadar and Handelman: the lower semicontinuous dimension functions are weakly dense in the space of all dimension functions. These results continue to hold in the broader setting of unital simple ASH algebras with slow dimension growth and stable rank one. Our main tool is a sharp bound on the radius of comparison of a recursive subhomogeneous C*-algebra. This is also used to construct uncountably many non-Morita-equivalent simple separable amenable C*-algebras with the same K-theory and tracial state space, providing a C*-algebraic analogue of McDuff's uncountable family of II_1 factors. We prove in passing that the range of the radius of comparison is exhausted by simple C*-algebras.Comment: 30 pages, no figure

    There is no new physics in the multiplicative anomaly

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    We discuss the role of the multiplicative anomaly for a complex scalar field at finite temperature and density. It is argued that physical considerations must be applied to determine which of the many possible expressions for the effective action obtained by the functional integral method is correct. This is done by first studying the non-relativistic field where the thermodynamic potential is well-known. The relativistic case is also considered. We emphasize that the role of the multiplicative anomaly is not to lead to new physics, but rather to preserve the equality among the various expressions for the effective action.Comment: 24 pages, RevTex, no figure

    Locally Trivial W*-Bundles

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    We prove that a tracially continuous W∗^*-bundle M\mathcal{M} over a compact Hausdorff space XX with all fibres isomorphic to the hyperfinite II1_1-factor R\mathcal{R} that is locally trivial already has to be globally trivial. The proof uses the contractibility of the automorphism group Aut(R)\mathrm{Aut}({\mathcal{R}}) shown by Popa and Takesaki. There is no restriction on the covering dimension of XX.Comment: 20 pages, this version will be published in the International Journal of Mathematic

    Delay of Disorder by Diluted Polymers

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    We study the effect of diluted flexible polymers on a disordered capillary wave state. The waves are generated at an interface of a dyed water sugar solution and a low viscous silicon oil. This allows for a quantitative measurement of the spatio-temporal Fourier spectrum. The primary pattern after the first bifurcation from the flat interface are squares. With increasing driving strength we observe a melting of the square pattern. It is replaced by a weak turbulent cascade. The addition of a small amount of polymers to the water layer does not affect the critical acceleration but shifts the disorder transition to higher driving strenghs and the short wave length - high frequency fluctuations are suppressed

    Piloting a digitally-mediated social story intervention for autistic children led by teachers within naturalistic school settings

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    BackgroundSocial stories (SS) are widely used within the autism community. However, research into their effectiveness is mixed at best and mainly relies on single case study designs. Additional support from the researcher is also often provided, raising questions as to the use and effectiveness of SS within usual school settings.MethodSeventeen school teachers developed and delivered personalised digitally-mediated SS with 22 autistic children (aged 5-11yrs) over a 4-week intervention period. Data was collected during a baseline period (1 week), throughout the 4-week intervention phase and at 6-week follow-up to consider changes in child behaviour, understanding and anxiety. A new assessment framework to evaluation treatment fidelity according to Gray’s 10 Criteria was also developed.ResultsWith the support of a new SS app teachers were able to carry out SS interventions with a high degree of fidelity within their usual school settings. Behavioural data showed significant improvements from baseline to week 4 for all measures relating to the goals of the intervention (including a reduction in anxiety and an increase in understanding), some of which were still present at follow-up.ConclusionThis study has demonstrated that technology can be used to support teachers to develop and deliver SS interventions to autistic children within school settings. Such technology can now be used to facilitate much needed future, larger, controlled studies within this area. Implications for practice are discussed

    Quantum gravitational contributions to quantum electrodynamics

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    Quantum electrodynamics describes the interactions of electrons and photons. Electric charge (the gauge coupling constant) is energy dependent, and there is a previous claim that charge is affected by gravity (described by general relativity) with the implication that the charge is reduced at high energies. But that claim has been very controversial with the situation inconclusive. Here I report an analysis (free from earlier controversies) demonstrating that that quantum gravity corrections to quantum electrodynamics have a quadratic energy dependence that result in the reduction of the electric charge at high energies, a result known as asymptotic freedom.Comment: To be published in Nature. 19 pages LaTeX, no figure
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