15 research outputs found
A Very High-Order Accurate Staggered Finite Volume Scheme for the Stationary Incompressible Navier–Stokes and Euler Equations on Unstructured Meshes
International audienceWe propose a sixth-order staggered finite volume scheme based on polynomial reconstructions to achieve high accurate numerical solutions for the incompressible Navier-Stokes and Euler equations. The scheme is equipped with a fixed-point algorithm with solution relaxation to speed-up the convergence and reduce the computation time. Numerical tests are provided to assess the effectiveness of the method to achieve up to sixth-order con-2 Ricardo Costa et al. vergence rates. Simulations for the benchmark lid-driven cavity problem are also provided to highlight the benefit of the proposed high-order scheme
The association of spinal osteoarthritis with lumbar lordosis
<p>Abstract</p> <p>Background</p> <p>Careful review of published evidence has led to the postulate that the degree of lumbar lordosis may possibly influence the development and progression of spinal osteoarthritis, just as misalignment does in other joints. Spinal degeneration can ensue from the asymmetrical distribution of loads. The resultant lesions lead to a domino- like breakdown of the normal morphology, degenerative instability and deviation from the correct configuration. The aim of this study is to investigate whether a relationship exists between the sagittal alignment of the lumbar spine, as it is expressed by lordosis, and the presence of radiographic osteoarthritis.</p> <p>Methods</p> <p>112 female subjects, aged 40-72 years, were examined in the Outpatients Department of the Orthopedics' Clinic, University Hospital of Heraklion, Crete. Lumbar radiographs were examined on two separate occasions, independently, by two of the authors for the presence of osteoarthritis. Lordosis was measured from the top of L<sub>1 </sub>to the bottom of L<sub>5 </sub>as well as from the top of L<sub>1 </sub>to the top of S<sub>1</sub>. Furthermore, the angle between the bottom of L<sub>5 </sub>to the top of S<sub>1</sub>was also measured.</p> <p>Results and discussion</p> <p>49 women were diagnosed with radiographic osteoarthritis of the lumbar spine, while 63 women had no evidence of osteoarthritis and served as controls. The two groups were matched for age and body build, as it is expressed by BMI. No statistically significant differences were found in the lordotic angles between the two groups</p> <p>Conclusions</p> <p>There is no difference in lordosis between those affected with lumbar spine osteoarthritis and those who are disease free. It appears that osteoarthritis is not associated with the degree of lumbar lordosis.</p
The association of spinal osteoarthritis with lumbar lordosis
Background: Careful review of published evidence has led to the postulate that the degree of lumbar lordosis may possibly influence the development and progression of spinal osteoarthritis, just as misalignment does in other joints. Spinal degeneration can ensue from the asymmetrical distribution of loads. The resultant lesions lead to a domino- like breakdown of the normal morphology, degenerative instability and deviation from the correct configuration. The aim of this study is to investigate whether a relationship exists between the sagittal alignment of the lumbar spine, as it is expressed by lordosis, and the presence of radiographic osteoarthritis. Methods: 112 female subjects, aged 40-72 years, were examined in the Outpatients Department of the Orthopedics-Clinic, University Hospital of Heraklion, Crete. Lumbar radiographs were examined on two separate occasions, independently, by two of the authors for the presence of osteoarthritis. Lordosis was measured from the top of L1 to the bottom of L5 as well as from the top of L1 to the top of S1. Furthermore, the angle between the bottom of L5 to the top of S1 was also measured. Results and discussion: 49 women were diagnosed with radiographic osteoarthritis of the lumbar spine, while 63 women had no evidence of osteoarthritis and served as controls. The two groups were matched for age and body build, as it is expressed by BMI. No statistically significant differences were found in the lordotic angles between the two groups Conclusions: There is no difference in lordosis between those affected with lumbar spine osteoarthritis and those who are disease free. It appears that osteoarthritis is not associated with the degree of lumbar lordosis. © 2010 Papadakis et al.
Accelerometry for Evaluation of Gait Pattern in Healthy Soccer Athletes
An accelerometer system was used to measure the characteristics of the
motion of 133 healthy male soccer athletes in a 30-s walking test and
the data obtained were analysed using the gait evaluation differential
entropy method (GEDEM). GEDEM processes gait acceleration data and
calculates an index that provides a quantitative evaluation of a
subject’s gait, at low cost and with negligible effect on the subject.
The GEDEM index was not significantly correlated with age, body weight,
body mass index, or the number of years of active training. The GEDEM
value for the anterior-posterior axis showed a small negative
statistically significant correlation with height and the vertical axis
was moderately and statistically significantly positively correlated
with the time spent training per week. The triaxial accelerometry system
described here is easy for subjects and testers to use, and enables
measurements to be made on the sports field to evaluate an athlete’s
musculoskeletal condition with respect to gait stability
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Ocean acoustic models for low frequency propagation in 2D and 3D environments
In this paper we are mainly concerned with the development of efficient computer models capable of accurately predicting the propagation of low-to-middle frequency sound in the sea, in axially symmetric (2D) and in fully 3D environments. The major physical features of the problem, i.e. a variable bottom topography, elastic properties of the subbottom structure, volume attenuation and other range inhomogeneities are efficiently treated. The computer models presented are based on normal mode solutions of the Helmholtz equation on the one hand, and on various types of numerical schemes for parabolic approximations of the Helmholtz equation on the other. A new coupled mode code is introduced to model sound propagation in range-dependent ocean environments with variable bottom topography, where the effects of an elastic bottom, of volume attenuation, surface and bottom roughness are taken into account. New computer models based on finite difference and finite element techniques for the numerical solution of parabolic approximations are also presented. They include an efficient modeling of the bottom influence via impedance boundary conditions, they cover wide angle propagation, elastic bottom effects, variable bottom topography and reverberation effects. All the models are validated on several benchmark problems and versus experimental data. Results thus obtained were compared with analogous results from standard codes in the literature
Pre-operative versus Post-operative Gait Variability in Patients with Acute Anterior Cruciate Ligament Deficiency
Change in gait variability at least 6 months after surgical
reconstruction of the anterior cruciate ligament (ACL) was assessed in
20 male patients with acute ACL deficiency and compared with
pre-operative data and that from 20 healthy male controls. Gait was
measured using a triaxial accelerometer and data were analysed by the
Gait Evaluation Differential Entropy Method (GEDEM) to determine gait
variability. Pain was assessed with a visual analogue scale and
functional ability with the Oswestry Disability Index and the
International Knee Documentation Committee score. Mean gait variability
was significantly lower after than before surgery, with values for the
anterior posterior axis being in the normal range of controls after 6
months, whereas in the mediolateral axis mean gait variability remained
significantly higher, indicating that some rotational instability
remained in the time-frame of the study. Pain and functional ability
scores improved after surgery compared with before surgery. The
combination of accelerometry and GEDEM may be a useful orthopaedic tool
for the post-operative evaluation of patients who have undergone ACL
reconstruction
Influence of Acute Anterior Cruciate Ligament Deficiency in Gait Variability
The objective of this study was to compare the gait variability of
patients with isolated anterior cruciate ligament (ACL) deficiency
(experimental group) with that of healthy individuals (control group).
The hypothesis was that the gait variability of the experimental group
would be higher than the control group. The experimental group consisted
of 20 men with an ACL tear and the control group consisted of 20 healthy
men without any neurological and/or musculoskeletal pathology or injury.
The gait acceleration signal was analysed using the Gait Evaluation
Differential Entropy Method (GEDEM). The GEDEM index of the experimental
group in the medio-lateral axis was significantly higher than that of
the control subjects. A receiver operating characteristic (ROC) analysis
was used to assess the diagnostic value of the method and to determine a
cut-off entropy value. The GEDEM cut-off value had a 95.6% probability
of separating isolated ACL patients from healthy subjects