2,656 research outputs found

    Climate variability and change : hydrological impacts

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    Dual mobility hip arthroplasty wear measurement: Experimental accuracy assessment using radiostereometric analysis (RSA)

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    SummaryIntroductionThe use of dual mobility cups is an effective method to prevent dislocations. However, the specific design of these implants can raise the suspicion of increased wear and subsequent periprosthetic osteolysis.HypothesisUsing radiostereometric analysis (RSA), migration of the femoral head inside the cup of a dual mobility implant can be defined to apprehend polyethylene wear rate.Study objectivesThe study aimed to establish the precision of RSA measurement of femoral head migration in the cup of a dual mobility implant, and its intra- and interobserver variability.Material and methodsA total hip prosthesis phantom was implanted and placed under weight loading conditions in a simulator. Model-based RSA measurement of implant penetration involved specially machined polyethylene liners with increasing concentric wear (no wear, then 0.25, 0.5 and 0.75mm). Three examiners, blinded to the level of wear, analyzed (10 times) the radiostereometric films of the four liners. There was one experienced, one trained, and one inexperienced examiner. Statistical analysis measured the accuracy, precision, and intra- and interobserver variability by calculating Root Mean Square Error (RMSE), Concordance Correlation Coefficient (CCC), Intra Class correlation Coefficient (ICC), and Bland-Altman plots.ResultsOur protocol, that used a simple geometric model rather than the manufacturer's CAD files, showed precision of 0.072mm and accuracy of 0.034mm, comparable with machining tolerances with low variability. Correlation between wear measurement and true value was excellent with a CCC of 0.9772. Intraobserver reproducibility was very good with an ICC of 0.9856, 0.9883 and 0.9842, respectively for examiners 1, 2 and 3. Interobserver reproducibility was excellent with a CCC of 0.9818 between examiners 2 and 1, and 0.9713 between examiners 3 and 1.DiscussionQuantification of wear is indispensable for the surveillance of dual mobility implants. This in vitro study validates our measurement method. Our results, and comparison with other studies using different measurement technologies (RSA, standard radiographs, Martell method) make model-based RSA the reference method for measuring the wear of total hip prostheses in vivo.Level of evidenceLevel 3. Prospective diagnostic study

    New discoveries of Middle Paleolithic human remains from the “Bau de l'Aubésier (Vaucluse, France)”

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    Excavations in Middle Paleolithic levels at the “Bau de l’Aubésier (Vaucluse)” during 2000 yielded a maxillary molar and a partial mandible from late Middle Pleistocene levels, plus a maxillary molar from the early Late Pleistocene. The Middle Pleistocene remains (Aubesier 10 and 11) have close morphological affinities to contemporaneous European human remains, and the Neandertal molar (Aubesier 12) falls well within Neandertal ranges of variation. The teeth are notable for a toothpick groove on Aubesier 10 and the large dental caries in Aubesier 12. The Aubesier 11 mandible exhibits extensive pathological alterations of the alveolar process, indicating serious impairment of mastication.Des fouilles dans les niveaux du Paléolithique moyen du Bau de l’Aubésier (Vaucluse) en 2000 ont livré une molaire supérieure et une grande partie d’une mandibule des niveaux du Pléistocène moyen tardif ainsi qu’une molaire supérieure du début du Pléistocène supérieure. Les restes du Pléistocène moyen (Aubésier 10 et 11) ont des affinités morphologiques avec les autres restes humains contemporaines d’Europe, et la molaire néandertalienne (Aubésier 12) est bien dans la variation des Néandertaliens. Sur Aubésier 10 se remarque un sulcus de cure-dent, ainsi qu’une grande carie dentaire sur Aubésier 12. La mandibule Aubésier 11 montre des altérations pathologiques au niveaux des alvéoles, ce qui indique une mastication difficile

    Observational Learning During Simulation-Based Training in Arthroscopy: Is It Useful to Novices?

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    This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.OBJECTIVE: Observing experts constitutes an important and common learning experience for surgical residents before operating under direct guidance. However, studies suggest that exclusively observing experts may induce suboptimal motor learning, and watching errors from non-experts performing simple motor tasks may generate better performance. We investigated whether observational learning is transferrable to arthroscopy learning using virtual reality (VR) simulation. SETTING/DESIGN: In our surgical simulation laboratory, we compared students learning basic skills on a VR arthroscopy simulator after watching an expert video demonstration of VR arthroscopy tasks or a non-expert video demonstration of the same tasks to a Control group without video demonstration. Ninety students in 3 observing groups (expert, non-expert, and Control) subsequently completed the same procedure on a VR arthroscopy simulator. We hypothesized the non-expert-watching group would outperform the expert-watching group, and both groups to outperform the Control group. We examined performance pretest, posttest, and 1 week later. PARTICIPANTS: Participants were recruited from the final year of medical school and the very early first year of surgical residency training programs (orthopaedic surgery, urology, plastic surgery, and general surgery) at Western University (Ontario, Canada). RESULTS: All participants improved their overall performance from pretest to retention (p < 0.001). At initial retention testing, non-expert-watching group outperformed the other groups in camera path length p < 0.05 and time to completion, p < 0.05, and both the expert/non-expert groups surpassed the Control group in camera path length (p < 0.05). CONCLUSION: We suggest that error-observation may contribute to skills improvement in the non-expert-watching group. Allowing novices to observe techniques/errors of other novices may assist internalization of specific movements/skills required for effective motor performances. This study highlights the potential effect of observational learning on surgical skills acquisition and offers preliminary evidence for peer-based practice (combined non-experts and experts) as a complementary surgical motor skills training strategy.This project was supported by a Physicians׳ Services Incorporated (PSI) Foundation, Canada grant. Funds were used to pay for salary and employee benefits (LvE). The PSI Foundation did not play a role in the investigation

    Association between Activity Space Exposure to Food Establishments and Individual Risk of Overweight

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    Objective: Environmental exposure to food sources may underpin area level differences in individual risk for overweight. Place of residence is generally used to assess neighbourhood exposure. Yet, because people are mobile, multiple exposures should be accounted for to assess the relation between food environments and overweight. Unfortunately, mobility data is often missing from health surveys. We hereby test the feasibility of linking travel survey data with food listings to derive food store exposure predictors of overweight among health survey participants. Methods: Food environment exposure measures accounting for non-residential activity places (activity spaces) were computed and modelled in Montreal and Quebec City, Canada, using travel surveys and food store listings. Models were then used to predict activity space food exposures for 5,578 participants of the Canadian Community Health Survey. These food exposure estimates, accounting for daily mobility, were used to model self-reported overweight in a multilevel framework. Median Odd Ratios were used to assess the proportion of between-neighborhood variance explained by such food exposure predictors. Results: Estimates of food environment exposure accounting for both residential and non-residential destinations were significantly and more strongly associated with overweight than residential-only measures of exposure for men. For women, residential exposures were more strongly associated with overweight than non-residential exposures. In Montreal, adjusted models showed men in the highest quartile of exposure to food stores were at lesser risk of being overweight considering exposure to restaurants (OR = 0.36 [0.21–0.62]), fast food outlets (0.48 [0.30–0.79]), or corner stores (0.52 [0.35–0.78]). Conversely, men experiencing the highest proportion of restaurants being fast-food outlets were at higher risk of being overweight (2.07 [1.25–3.42]). Women experiencing higher residential exposures were at lower risk of overweight. Conclusion: Using residential neighbourhood food exposure measures may underestimate true exposure and observed associations. Using mobility data offers potential for deriving activity space exposure estimates in epidemiological models
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