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