Optimización de torres de alta tensión y su análisis frente a vientos de alta intensidad

Esta tesis tiene como objetivo el desarrollo de una herramienta computacional para el análisis y optimización de torres de líneas de alta tensión. La herramienta está basada en el método de elementos finitos, siendo las torres modeladas como reticulados tridimensionales. Los códigos desarrollados se realizaron en el lenguaje del ambiente Matlab, y permiten optimizar una estructura reticulada bajo restricciones mecánicas y geométricas. La herramienta fue utilizada para optimizar una torre típica de transmisión de energía eléctrica. La estructura optimizada fue analizada estudiando las frecuencias naturales y sus modos de vibración, la inestabilidad global del sistema bajo la hipótesis de pequeños y grandes desplazamientos, y su comportamiento dinámico frente a un perfil de viento proveniente de una tormenta descendente. Se observó que la torre optimizada tiene su masa determinada mayormente por los perfiles de acero utilizados, siendo su geometría similar a la del diseño de partida. Para la torre optimizada se presenta el estudio de las primeras seis frecuencias naturales, junto con sus modos de vibración, observando que esas frecuencias están en el rango admisible establecido por las normas técnicas. Los resultados obtenidos en los análisis de inestabilidad global muestran que no se producirá una falla global en forma previa a las fallas locales. El análisis dinámico determinó que la torre optimizada no cumple con los requisitos de diseño cuando se la somete a una tormenta como la que fue simulada, lo cual muestra que la acción de este tipo de tormentas debe ser tenida en cuenta en el proyecto de la torre, por ejemplo integrando restricciones adicionales en la formulación de optimización. Las herramientas desarrolladas son de código abierto y ofrecidas libremente para investigaciones futuras

Rotational positioning of the tibial tray in total knee arthroplasty: A CT evaluation

SummaryIntroductionVarious surgical techniques have been described to set the rotational alignment of the tibial baseplate during total knee arthroplasty. The self-positioning method (“self-adjustment”) aligns the tibial implant according to the rotational alignment of the femoral component which is used as a reference after performing repeated knee flexion/extension cycles. Postoperative computed tomography scanning produces accurate measurements of the tibial baseplate rotational alignment with respect to the femoral component.HypothesisThe rotational positioning of the tibial baseplate matches the rotation of the femoral component with parallel alignment to the prosthetic posterior bicondylar axis.Patients and methodsA 3-month follow-up CT scan was carried out after primary total knee arthroplasty implanted in osteoarthritic patients with a mean 7.8° varus deformity of the knee in 50 cases and a mean 8.7° valgus deformity of the knee in 44 cases. The NexGen LPS Flex (Zimmer) fixed-bearing knee prosthesis was used in all cases. An independant examiner (not part of the operating team) measured different variables: the angle between the anatomic transepicondylar axis and the posterior bicondylar axis of the femoral prosthesis (prosthetic posterior condylar angle), the angle between the posterior bicondylar axis and the posterior marginal axis of the tibial prosthesis, the angle between the posterior marginal axis of the tibial prosthesis and the posterior marginal axis of the tibial bone and finally the angle between the anatomic transepicondylar axis and the posterior marginal axis of the tibial prosthesis.ResultsFor the genu varum and genu valgum subgroups, the mean posterior condylar axis of the femoral prosthesis was 3.1° (SD: 1.91; extremes 0° to 17.5°) and 4.7° (SD: 2.7; extremes 0° to 11°) respectively. The tibial baseplate was placed in external rotation with respect to the femoral component: 0.7° (SD : 4.45; extremes –9.5° to 9.8°) and 0.9° (SD: 4.53; extremes –10.8° to 9.5°), but also to the native tibia: 6.1° (SD: 5.85; extremes –4.6° to 22.5°) and 12.5° (SD: 8.6; extremes –10° to 28.9°). The tibial component was placed in internal rotation relative to the anatomic transepicondylar axis: 1.9° (SD : 4.93; extremes –13.6° to 7°) and 3° (SD : 4.38; extremes –16.2° to 4.8°).DiscussionThe tibial component is aligned parallel to the femoral component whatever the initial frontal deformity (P≅0.7). However, a difference was observed between the rotational alignment of the tibial baseplate and the native tibia depending on the initial deformity and could be attributed to the morphological variations of the bony tibial plateau in case of genu valgum.ConclusionThe self-positioning method is a reproducible option when using this type of implant since it allows the tibial component to be positioned parallel to the posterior border of the femur.Level of evidenceLevel III. Observational prospective study

Functional outcomes after non-operative treatment of irreparable massive rotator cuff tears: Prospective multicenter study in 68 patients

BACKGROUND: Massive rotator cuff tears (RCTs) account for 10% to 40% of all RCTs and over 80% of re-tears. The objectives of this prospective study were to assess functional outcomes 6 and 12 months after starting non-operative therapy for an irreparable massive RCT and to identify predictors of good outcomes of non-operative treatment. HYPOTHESIS: Non-operative treatment deserves to be tried because it can produce improvements in patients with irreparable massive RCTs. MATERIAL AND METHODS: A prospective multicenter (12 centres) study was conducted between March 2015 and March 2016. Consecutive patients managed non-operatively for RCTs involving two or more tendons including one with a fatty infiltration score greater than 2 were included. Non-operative treatment consisted in rehabilitation and sub-acromial corticosteroid injections. Functional outcomes were assessed based on the Constant score and Subjective Shoulder Value (SSV) after 3, 6, and 12 months. RESULTS: Of 71 included patients, 3 underwent surgery during the study year, leaving 68 patients for the analysis of 12-month outcomes. Significant improvements were noted after 12 months in the Constant score (from 40.7 at baseline to 57.7 after 6 months and 57.1 after 12 months), in each of its items except force, and in the SSV. Constant score values after 6 and 12 months were not significantly different. No significant differences in functional outcomes were found across initial tear type. CONCLUSION: Non-operative treatment produces significant functional gains in patients with irreparable massive RCTs. These gains are obtained after 6 months. Surgery can therefore be considered if the outcome is unsatisfactory after 6 months

Optimization of the glenoid component positioning of a shoulder prosthesis : from the 3D reconstruction to the augmented reality

Deux méthodes d’assistance opératoire, pour le positionnement du composant glénoïdien d’une prothèse d’épaule, sont explorées. Elles ont pour dénominateur commun une reconstruction 3D première de la glène pathologique à implanter. Une approche essentiellement clinique, avec des travaux d’application pratique, est proposée pour la technologie des Patients Specific Implants (PSI), dont l’utilisation en orthopédie est croissante. Une approche davantage technologique est ensuite proposée, de type Réalité Augmentée, jusqu’à maintenant encore inexploitée dans le champ de la chirurgie orthopédique. La faisabilité de cette approche, les conditions d’emploi des technologies inhérentes, ont été étudiées. En amont, un nouveau type d’information pour implémenter, sur le support connecté (lunettes électroniques), l’application de réalité, est proposé, avec la modélisation mathématique par régression linéaire multiple d’une glène normale. L’objectif secondaire est d’obtenir une banque de données dites de glènes génériques normales, pouvant servir de référence à la reconstitution d’une glène pathologique à traiter, après un processus de morphing.In this thesis, two methods of operating assistance for the positioning of the glenoid component of a shoulder prosthesis, are addressed. They have in common a preliminary 3D reconstruction of the pathological glenoid to implant. A main clinical approach, with practice studies, is proposed for the Patient Specific Implants technology, which is currently used in orthopaedics. Then a main prospective and technological approach is proposed with the Augmented Reality, while it is so far untapped in the field of orthopaedic surgery. The feasibility of this last technology, as well as the tools and the manual for its use, were studied. Upstream, a new type of information to implement the augmented reality connected application support is offered, with mathematical modeling by multiple linear regression of a normal glenoid. The second goal is to build a normal generic glenoids database. It can be used as reference to the reconstruction of a pathological glenoid to treat, after a morphing process step

Los nuevos modelos de negocios de alquiler de películas producto del avance tecnológico y el uso de Internet. Análisis de los casos Blockbuster, Netflix y Redbox

Fil: Berhouet, Santiago. Universidad de San Andrés. Escuela de Administración y Negocios; Argentina.Artopoulos, Alejandr

Mobilités et encoche du pilier de l'omoplate dans les prothèses d'épaule inversées (influence de la modularité des implants glénoïdiens et de la rétroversion humérale)

TOURS-BU Médecine (372612103) / SudocSudocFranceF

Apport du Doppler tissulaire en échocardiographie de stress

TOURS-BU Médecine (372612103) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF