129 research outputs found

    Postoperative temporomandibular dysfunction in patients with fractures of the zygomatic complex : a prospective follow-up study

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    The aim of this prospective follow-up study was to clarify the incidence and characteristics of dysfunction of the temporomandibular joint (TMJ) in patients treated surgically for fractures of the zygomatic complex. Patients were evaluated on presentation and six months after injury to assess the function of the masticatory system using the Helkimo index, which incorporates two complementary subindices: the subjective symptomatic (anamnestic) index (A(i)) and the objective clinical dysfunction index (D-i). Forty-five patients (12 women and 33 men, mean (range) age 44 (21-83) years) completed the study. Six patients developed subjective symptoms of dysfunction of the TMJ during follow-up, in four of whom they were severe. Clinical findings were noted in 38 patients but without significant association with subjective symptoms. Dysfunction of the TMJ is common six months after surgical treatment of a fracture of the zygomatic complex, and patients with such fractures should be evaluated for temporomandibular dysfunction during follow-up and referred for treatment when necessary. (C) 2018 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.Peer reviewe

    Mass of a quantum 't Hooft-Polyakov monopole

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    The quantum mechanical mass of 't Hooft-Polyakov monopoles in the four-dimensional Georgi-Glashow is calculated non-perturbatively using lattice Monte Carlo simulations. This is done by imposing twisted boundary conditions that ensure there is one unit of magnetic charge on the lattice, and measuring the free energy difference between this ensemble and the vacuum. In the weak-coupling limit, the results can be used to determine the quantum correction to the classical mass, once renormalisation of couplings is taken properly into account. The methods can also be used to study the masses at strong coupling, i.e., near the critical point, where there are hints of a possible electric-magnetic duality.Comment: 17 pages, 4 figures. Typos corrected, one reference adde

    Fluxoid formation: size effects and non-equilibrium universality

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    Simple causal arguments put forward by Kibble and Zurek suggest that the scaling behaviour of condensed matter at continuous transitions is related to the familiar universality classes of the systems at quasi-equilibrium. Although proposed 25 years ago or more, it is only in the last few years that it has been possible to devise experiments from which scaling exponents can be determined and in which this scenario can be tested. In previous work, an unusually high Kibble-Zurek scaling exponent was reported for spontaneous fluxoid production in a single isolated superconducting Nb loop, albeit with low density. Using analytic approximations backed up by Langevin simulations, we argue that densities as small as these are too low to be attributable to scaling, and are conditioned by the small size of the loop. We also reflect on the physical differences between slow quenches and small rings, and derive some criteria for these differences, noting that recent work on slow quenches does not adequately explain the anomalous behaviour seen here.Comment: 7 pages, 4 figures, presentation given at CMMP 201

    Gravitational Radiation by Cosmic Strings in a Junction

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    The formalism for computing the gravitational power radiation from excitations on cosmic strings forming a junction is presented and applied to the simple case of co-planar strings at a junction when the excitations are generated along one string leg. The effects of polarization of the excitations and of the back-reaction of the gravitational radiation on the small scale structure of the strings are studied.Comment: minor changes added, the published version in JCA

    Non-Gaussianity from the hybrid potential

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    We study the hybrid inflationary potential in a regime where the defect field is light, and more than 60 e-folds of accelerated expansion occur after the symmetry breaking transition. Using analytic and numerical techniques, we then identify parameter values within this regime for which the statistics of the primordial curvature perturbation are significantly non-Gaussian. Focusing on this range of parameters, we provide a specific example which leads to an observationally consistent power spectrum, and a level of non-Gaussianity within current WMAP bounds and in reach of the Planck satellite. An interesting feature of this example is that the initial conditions at horizon crossing appear quite natural.Comment: 9 pages, 7 figure

    Zurek-Kibble domain structures: The Dynamics of Spontaneous Vortex formation in Annular Josephson Tunnel Junctions

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    Phase transitions executed in a finite time show a domain structure with defects, that has been argued by Zurek and Kibble to depend in a characteristic way on the quench rate. In this letter we present an experiment to measure the Zurek-Kibble scaling exponent sigma. Using symmetric and long Josephson Tunnel Junctions, for which the predicted index is sigma = 0.25, we find sigma = 0.27 +/- 0.05. Further, there is agreement with the ZK prediction for the overall normalisation.Comment: To be published in Phys. Rev. Lett

    Defect formation and local gauge invariance

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    We propose a new mechanism for formation of topological defects in a U(1) model with a local gauge symmetry. This mechanism leads to definite predictions, which are qualitatively different from those of the Kibble-Zurek mechanism of global theories. We confirm these predictions in numerical simulations, and they can also be tested in superconductor experiments. We believe that the mechanism generalizes to more complicated theories.Comment: REVTeX, 4 pages, 2 figures. The explicit form of the Hamiltonian and the equations of motion added. To appear in PRL (http://prl.aps.org/

    Quantum kink and its excitations

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    We show how detailed properties of a kink in quantum field theory can be extracted from field correlation functions. This makes it possible to study quantum kinks in a fully non-perturbative way using Monte Carlo simulations. We demonstrate this by calculating the kink mass as well as the spectrum and approximate wave functions of its excitations. This way of measuring the kink mass has clear advantages over the existing approaches based on creation and annihilation operators or the kink free energy. Our methods are straightforward to generalise to more realistic theories and other defect types.Comment: 21 pages, 11 figures, v2: typos corrected, references adde

    Three-loop critical exponents, amplitude functions, and amplitude ratios from variational perturbation theory

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    We use variational perturbation theory to calculate various universal amplitude ratios above and below T_c in minimally subtracted phi^4-theory with N components in three dimensions. In order to best exhibit the method as a powerful alternative to Borel resummation techniques, we consider only to two- and three-loops expressions where our results are analytic expressions. For the critical exponents, we also extend existing analytic expressions for two loops to three loops.Comment: Author Information under http://www.physik.fu-berlin.de/~kleinert/institution.html . Latest update of paper (including all PS fonts) at http://www.physik.fu-berlin.de/~kleinert/kleiner_re318/preprint.htm
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