1,759 research outputs found
Shelf arthroplasties long-term outcome: Influence of labral tears. A prospective study at a minimal 16 years’ follows up
SummaryIntroductionOsteoarthritis lesions extent and dysplasia severity (negative vertical center edge [CE] angle) are recognized as unfavorable criteria for the survival of shelf arthroplasties performed for correcting hip dysplasia. Labral tears have recently been described on dysplastic hips, indicating beginning osteoarthritis and worsening the risk of instability.HypothesisThe labral tears identified in the course of shelf arthroplasty procedures for correction of hip dysplasia carry a predictive value for the survival of this operation.ObjectivesEvaluate this hypothesis at the intermediate term in a long-term prospective observational study.Patient and methodsEighteen adult patients (18 dysplastic hips) having undergone shelf arthroplasty were included consecutively in a continuous prospective study. At the time the shelf arthroplasty was performed, a hip arthroscopic exam was carried out to search for and resect a labral tear if necessary. Fifteen patients were reviewed with a minimum follow-up of 16 years. Two patients died and one patient was lost to follow-up.ResultsDuring arthroscopic exploration, 10 hips presented labral tears (55.6%). At a mean follow-up of 16.3 years (range, 16–18 years), eight hips underwent hip arthroplasty. Of these hips, only one did not present a labral tear. The seven other hips had a tear of the labrum (p<0.001). The overall survival rate was 41.3%; it was 83.3% for hips with no labral tear and 15.2% for hips with a lesion of the labrum (p=0.048).Discussion and conclusionLabral tears had a negative impact on the outcome of shelf arthroplasty for hip dysplasia. This lesion therefore warrants being sought using appropriate exploration techniques (MRI or CT-arthrography) before shelf arthroplasty surgery. The existence of a preoperative labral tear does not seem to cast doubt on shelf arthroplasty itself. However, it should be identified so as to set objectives and expectations: long-term survival is significantly lower in the presence of a labral tear. It seems preferable to repair this type of lesion with arthroscopic guidance during shelf arthroplasty to prevent a potential source of residual pain, keeping in mind that secondary resection will be more difficult after covering the lesion.Level of evidenceLevel 3 prospective observational prognostic study
Chromosomal rearrangement segregating with adrenoleukodystrophy: associated changes in color vision.
Energy-sensitive imaging detector applied to the dissociative recombination of D2H+
We report on an energy-sensitive imaging detector for studying the
fragmentation of polyatomic molecules in the dissociative recombination of fast
molecular ions with electrons. The system is based on a large area (10 cm x 10
cm) position-sensitive, double-sided Si-strip detector with 128 horizontal and
128 vertical strips, whose pulse height information is read out individually.
The setup allows to uniquely identify fragment masses and is thus capable of
measuring branching ratios between different fragmentation channels, kinetic
energy releases, as well as breakup geometries, as a function of the relative
ion-electron energy. The properties of the detection system, which has been
installed at the TSR storage ring facility of the Max-Planck Institute for
Nuclear Physics in Heidelberg, is illustrated by an investigation of the
dissociative recombination of the deuterated triatomic hydrogen cation D2H+. A
huge isotope effect is observed when comparing the relative branching ratio
between the D2+H and the HD+D channel; the ratio 2B(D2+H)/B(HD+D), which is
measured to be 1.27 +/- 0.05 at relative electron-ion energies around 0 eV, is
found to increase to 3.7 +/- 0.5 at ~5 eV.Comment: 11 pages, 12 figures, submitted to Physical Review
Dissociative recombination measurements of HCl+ using an ion storage ring
We have measured dissociative recombination of HCl+ with electrons using a
merged beams configuration at the heavy-ion storage ring TSR located at the Max
Planck Institute for Nuclear Physics in Heidelberg, Germany. We present the
measured absolute merged beams recombination rate coefficient for collision
energies from 0 to 4.5 eV. We have also developed a new method for deriving the
cross section from the measurements. Our approach does not suffer from
approximations made by previously used methods. The cross section was
transformed to a plasma rate coefficient for the electron temperature range
from T=10 to 5000 K. We show that the previously used HCl+ DR data
underestimate the plasma rate coefficient by a factor of 1.5 at T=10 K and
overestimate it by a factor of 3.0 at T=300 K. We also find that the new data
may partly explain existing discrepancies between observed abundances of
chlorine-bearing molecules and their astrochemical models.Comment: Accepted for publication in ApJ (July 7, 2013
On the Bergman representative coordinates
We study the set where the so-called Bergman representative coordinates (or
Bergman functions) form an immersion. We provide an estimate of the size of a
maximal geodesic ball with respect to the Bergman metric, contained in this
set. By concrete examples we show that these estimates are the best possible.Comment: 20 page
Pointwise estimates for the Bergman kernel of the weighted Fock space
We prove upper pointwise estimates for the Bergman kernel of the weighted
Fock space of entire functions in where is a
subharmonic function with a doubling measure. We derive estimates
for the canonical solution operator to the inhomogeneous Cauchy-Riemann
equation and we characterize the compactness of this operator in terms of
Destabilizing effects of visual environment motions simulating eye movements or head movements
In the present paper, we explore effects on the human of exposure to a visual virtual environment which has been enslaved to simulate the human user's head movements or eye movements. Specifically, we have studied the capacity of our experimental subjects to maintain stable spatial orientation in the context of moving their entire visible surroundings by using the parameters of the subjects' natural movements. Our index of the subjects' spatial orientation was the extent of involuntary sways of the body while attempting to stand still, as measured by translations and rotations of the head. We also observed, informally, their symptoms of motion sickness
Boundaries of Siegel Disks: Numerical Studies of their Dynamics and Regularity
Siegel disks are domains around fixed points of holomorphic maps in which the maps are locally linearizable (i.e., become a rotation under an appropriate change of coordinates which is analytic in a neighborhood of the origin). The dynamical behavior of the iterates of the map on the boundary of the Siegel disk exhibits strong scaling properties which have been intensively studied in the physical and mathematical literature. In the cases we study, the boundary of the Siegel disk is a Jordan curve containing a critical point of the map (we consider critical maps of different orders), and there exists a natural parametrization which transforms the dynamics on the boundary into a rotation. We compute numerically this parameterization and use methods of harmonic analysis to compute the global Holder regularity of the parametrization for different maps and rotation numbers. We obtain that the regularity of the boundaries and the scaling exponents are universal numbers in the sense of renormalization theory (i.e., they do not depend on the map when the map ranges in an open set), and only depend on the order of the critical point of the map in the boundary of the Siegel disk and the tail of the continued function expansion of the rotation number. We also discuss some possible relations between the regularity of the parametrization of the boundaries and the corresponding scaling exponents. (C) 2008 American Institute of Physics.NSFMathematic
Proof of the Hyperplane Zeros Conjecture of Lagarias and Wang
We prove that a real analytic subset of a torus group that is contained in
its image under an expanding endomorphism is a finite union of translates of
closed subgroups. This confirms the hyperplane zeros conjecture of Lagarias and
Wang for real analytic varieties. Our proof uses real analytic geometry,
topological dynamics and Fourier analysis.Comment: 25 page
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