Contribution of individual musculo-tendon forces to the axial compression force of the femur during normal gait

Recent musculoskeletal models allow the investigation of the contribution of individual musculo-tendon forces to the locomotion dynamics. However, most of the studies are based on a forward dynamics with a high computational cost and have principally investigated the contribution to the ground reaction forces and the centre of mass acceleration. The aim of this study was to apply a pseudo-inverse method to a musculoskeletal model that includes the contact, ligament and bone forces. The results replicated well the literature for the contributions of individual musculo-tendon forces to both the vertical ground reaction force and the total tibiofemoral contact force, and provide new insights for the axial compression force of the femur during normal gait.Les modèles musculo-squelettiques récents permettent d'estimer la contribution des forces musculo-tendineuses à la dynamique de locomotion. Cependant, la plupart des études utilisent une formulation en dynamique directe avec des temps de calculs importants et se focalisent principalement sur la contribution aux forces de réaction au sol ou à l'accélération du centre de masse. L'objectif de cette étude était d'appliquer une méthode basée sur une pseudo-inverse à un modèle musculo-squelettique incluant les forces articulaires, ligamentaires et osseuses. Les résultats reproduisent bien la littérature pour la contribution des forces musculo-tendineuses à la force de réaction au sol et à la force de contact tibiofémorale et donnent un nouvel éclairage pour la force de compression du fémur pendant la marche

SIMULTANEOUS PREDICTION OF MUSCULO-TENDON, JOINT CONTACT, LIGAMENT AND BONE FORCES IN THE LOWER LIMB DURING GAIT USING A ONE-STEP STATIC OPTIMISATION PROCEDURE Florent MOISSENET CNRFR -Rehazenter, Laboratoire d'Analyse du Mouvement et de la Posture, L-267

ABSTRACT Instrumented prostheses, by measuring joint contact forces during a movement, give nowadays a unique opportunity to validate the ability of musculo-skeletal models in predicting internal forces. In this study, a rigid multi-body musculo-skeletal model, allowing computing the musculo-tendon, joint contact, ligament and bone forces all together by static optimisation, using a weighted criterion, is presented. The results show that the musculo-tendon forces are generally in accordance with the envelopes of the main peaks of the subject's EMG signals and that the amplitudes and patterns of the predicted joint contact, ligament and bone forces are in a good agreement with the measurements and with the literature. By allowing the introduction of other forces than the musculo-tendon forces in the static optimisation, this study opens new horizons in order to better model the human physiology (e.g., joint pain)

Cross Section Measurements of Hard Diffraction at the SPS-Collider

The UA8 experiment previously reported the observation of jets in diffractive events containing leading protons (``hard diffraction''), which was interpreted as evidence for the partonic structure of an exchanged Reggeon, believed to be the Pomeron . In the present Letter, we report the final UA8 hard-diffractive (jet) cross section results and their interpretation. After corrections, the fraction of single diffractive events with mass from 118 to 189 GeV that have two scattered partons, each with Et_jet > 8 GeV, is in the range 0.002 to 0.003 (depending on x_p). We determine the product, fK, of the fraction by which the Pomeron's momentum sum rule is violated and the normalization constant of the Pomeron-Flux-Factor of the proton. For a pure gluonic- or a pure qqbar-Pomeron , respectively: fK = 0.30 +- 0.05 +- 0.09) and (0.56 +- 0.09 +- 0.17) GeV^-2.Comment: 20 pages, 5 Encapsulated Postscript figures, LaTex, Final Version, Physics Letters B (in Pess 1998

A Study of Inclusive Double-Pomeron-Exchange in p pbar -> p X pbar at root s = 630 GeV

We report measurements of the inclusive reaction, p pbar -> p X pbar, in events where either or both the beam-like final-state baryons were detected in Roman-pot spectrometers and the central system was detected in the UA2 calorimeter. A Double-Pomeron-Exchange (DPE) analysis of these data and single diffractive data from the same experiment demonstrates that, for central masses of a few GeV, the extracted Pomeron-Pomeron total cross section exhibits an enhancement which exceeds factorization expectations by an order-of-magnitude. This may be a signature for glueball production. The enhancement is shown to be independent of uncertainties connected with possible non-universality of the Pomeron flux factor. Based on our analysis, we present DPE cross section predictions, for unit (1 mb) Pomeron-Pomeron total cross section, at the Tevatron, LHC and the 920 GeV fixed-target experiment, HERA-B.Comment: 52 pages, 27 Encapsulated Postscript figures, 3 Tables, LaTex, Revised version as it will appear in European Physics Journal

The age of reason for FDG PET image-derived indices.

International audiencen.

Metabolically active volumes automatic delineation methodologies in PET imaging: review and perspectives

International audiencePET imaging is now considered a gold standard tool in clinical oncology, especially for diagnosis purposes. More recent applications such as therapy follow up or tumor targeting in radiotherapy require a fast, accurate and robust metabolically active tumor volumes on emission images, which cannot be obtained through manual contouring. This clinical need has sprung a large number of methodological developments regarding automatic methods to defined tumor volumes on PET images. This paper reviews most of the methodologies that have been recently proposed and discusses their framework and methodological and/or clinical validation. Perspectives regarding the future work to be done are also suggested

Estrategias de Internacionalización de una Multilatina en el sector servicios. Caso: Avianca-Taca Holding S.A.

This paper explores how existing internationalization theories can be applied to a Multilatina in the service sector, using the case of Avianca-Taca Holdings S.A. as an example. This paper introduces the company by analyzing the context in which it grew, starting with the service sector in Colombia, which is its country of origin. This paper also analyzes the international and domestic air transportation industry alongside the history of Avianca-Taca Holdings S.A. It describes in detail the internationalization program undertaken by the company and analyzes it based on three existing theories that may explain why such choices were made instead of others available. This paper explores different applications of these traditional theories. By this token, it concludes that, rather than using a brand new theory and aspiring to cover a large array of services, it is wiser to make decisions with a more comprehensive scope and use existing theories to adapt an efficient internationalization strategy to a particular context, region or country.Este artículo explora como las teorías de internacionalización existentes pueden ser aplicadas a una Multilatina del sector servicios, tomando como ejemplo el caso de Avianca-Taca Holdings S.A. El artículo presenta a la compañía analizando el contexto en el cual se desarrolló, empezando con el sector servicios en Colombia, su país de origen; la industria del transporte aéreo tanto a nivel nacional como internacional; y la historia de la compañía misma. El artículo describe en detalle el proceso de internacionalización llevado a cabo por la compañía y lo analiza bajo la luz de tres teorías existentes, las cuales pueden explicar porque dichos procesos fueron elegidos entre todos los disponibles. El artículo concluye que en lugar de buscar nuevas teorías que aspiren a explicar el amplio espectro de los servicios, es conveniente usar las teorías existentes para adaptar una estrategia de internacionalización eficiente a cada contexto particular de industria, región o país

Estrategias de Internacionalización de una Multilatina en el sector servicios. Caso: Avianca-Taca Holding S.A.

This paper explores how existing internationalization theories can be applied to a Multilatina in the service sector, using the case of Avianca-Taca Holdings S.A. as an example. This paper introduces the company by analyzing the context in which it grew, starting with the service sector in Colombia, which is its country of origin.  This paper also analyzes the international and domestic air transportation industry alongside the history of Avianca-Taca Holdings S.A. It describes in detail the internationalization program undertaken by the company and analyzes it based on three existing theories that may explain why such choices were made instead of others available. This paper explores different applications of these traditional theories. By this token, it concludes that, rather than using a brand new theory and aspiring to cover a large array of services, it is wiser to make decisions with a more comprehensive scope and use existing theories to adapt an efficient internationalization strategy to a particular context, region or country.Este artículo explora como las teorías de internacionalización existentes pueden ser aplicadas a una Multilatina del sector servicios, tomando como ejemplo el caso de Avianca-Taca Holdings S.A. El artículo presenta a la compañía analizando el contexto en el cual se desarrolló, empezando con el sector servicios en Colombia, su país de origen; la industria del transporte aéreo tanto a nivel nacional como internacional; y la historia de la compañía misma. El artículo describe en detalle el proceso de internacionalización llevado a cabo por la compañía y lo analiza bajo la luz de tres teorías existentes, las cuales pueden explicar porque dichos procesos fueron elegidos entre todos los disponibles. El artículo concluye que en lugar de buscar nuevas teorías que aspiren a explicar el amplio espectro de los servicios, es conveniente usar las teorías existentes para adaptar una estrategia de internacionalización eficiente a cada contexto particular de industria, región o país

Detection of energy waste in French households thanks to a co-clustering model for multivariate functional data

The exponential growth of smart devices in all aspects of everyday life leads to make common the collection of high frequency data. Those data can be seen as multivariate functional data: quantitative entities evolving along time, for which there is a growing needs of methods to summarize and understand them. The database that have motivated our project is supplied by the historical French electricity provider whose aim is to detect poorly insulated buildings, anomalies or long periods of absence. Their motivation is to answer COP24 requirements to reduce energy waste and to adapt electric load. To this end, a novel co-clustering model for multivariate functional data is defined. The model is based on a functional latent block model which assumes for each block a probabilistic distribution for multivariate functional principal component scores. A Stochastic EM algorithm, embedding a Gibbs sampler is proposed for model inference, as well as model selection criteria for choosing the number of co-clusters