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University of Technology of Compiègne, France

Schnell F.,Rennes1 University | Schnell F.,University of Rennes 2 - Upper Brittany | Schnell F.,French Institute of Health and Medical Research | Riding N.,Aspetar | And 11 more authors.

Background-Pathological T-wave inversion (PTWI) is rarely observed on the ECG of healthy athletes, whereas it is common in patients with certain cardiac diseases. All ECG interpretation guidelines for use within athletes state that PTWI (except in leads aVR, III and V1 and in V1-V4 when preceded by domed ST segment in asymptomatic Afro-Caribbean athletes only) cannot be considered a physiological adaptation. The aims of the present study were to prospectively determine the prevalence of cardiac pathology in athletes presenting with PTWI, and to examine the efficacy of cardiac magnetic resonance in the work-up battery of further examinations. Methods and Results-Athletes presenting with PTWI (n=155) were investigated with clinical examination, ECG, echocardiography, exercise testing, 24h Holter ECG, and cardiac magnetic resonance. Cardiac disease was established in 44.5% of athletes, with hypertrophic cardiomyopathy (81%) the most common pathology. Echocardiography was abnormal in 53.6% of positive cases, and cardiac magnetic resonance identified a further 24 athletes with disease. Five athletes (7.2%) considered normal on initial presentation subsequently expressed pathology during follow-up. Familial history of sudden cardiac death and ST-segment depression associated with PTWI were predictive of cardiac disease. Conclusions-PTWI should be considered pathological in all cases until proven otherwise, because it was associated with cardiac pathology in 45% of athletes. Despite echocardiography identifying pathology in half of these cases, cardiac magnetic resonance must be considered routine in athletes presenting with PTWI with normal echocardiography. Although exclusion from competitive sport is not warranted in the presence of normal secondary examinations, annual follow-up is essential to ascertain possible disease expression. © 2015 American Heart Association, Inc. Source

Liouane Z.,University of Monastir | Lemlouma T.,Rennes1 University | Roose P.,University of Pau and Pays de lAdour | Weis F.,Rennes1 University | Messaoud H.,University of Monastir
SENSORNETS 2016 - Proceedings of the 5th International Confererence on Sensor Networks

Recognizing activities of daily living plays an important role in healthcare. It is necessary to use an adapted model to simulate the human behavior in a domestic space to monitor the patient harmonically and to intervene in the necessary time. In this paper we tackle this problem using the hierarchical hidden Markov model for representing and recognizing complex indoor activities, we propose a new grammar "Home By Room Activities language" to facilitate the complexity of human scenarios and hold us account to the abnormal activities. © Copyright 2016 by SCITEPRESS- Science and Technology Publications, Lda. All rights reserved. Source

Carvou E.,Rennes1 University | El Abdi R.,Rennes1 University | Razafiarivelo J.,British Petroleum | Benjemaa N.,Rennes1 University | Zindine E.M.,British Petroleum
Measurement: Journal of the International Measurement Confederation

A connector provides a separable interface between two subsystems of an electronic system. The main function of the connector is to transmit a signal or distribute power. For power connectors, heating can lead to an increase in contact resistance and sometimes even to contact surface melting and thus to connector damage. In this study, the mechanical behaviour and heat evolution of a commercial power connector used in the automotive industry was undertaken. Using an experimental set-up, the mechanical insertion force, the temperature and the resistance evolution were measured. To quantify these parameters at the contact zone, two numerical modellings, using the finite element software Ansys, were employed to give the change of the insertion force during several insertion-extraction cycles and to solve the differential equations for heat transfer in a transitory mode. Adapted values of thermal and electrical contact conductances introduced into the numerical modelling, resulted in good values for both contact resistance and contact temperature, which were verified by experiments. © 2012 Elsevier Ltd. All rights reserved. Source

Baux C.,Rennes1 University | Phelipot-Mardele A.,Rennes1 University | Lanos C.,Rennes1 University | Pierre A.,Rennes1 University
Key Engineering Materials

Tested super sulfated cements (SSC) are composed of various amounts of ground granulated blast furnace slag, gypsum or activated gypsum and Portland cement. Our initial results on the optimization of the composition and of the curing conditions of such cements are presented herein. Tests are conducted on the basis of standard mortar with two different water/binder ratios according to old and new standards for SSC. Four types of curing are used: laboratory, wet room and immersion at 20°C or 40°C. Mechanical performances are assessed at 2, 7, 28, 60 and 90 days on standard mortar samples (binder/sand mass ratio = 1/3). This study shows that thanks to an optimization of the Portland cement content, it is possible to obtain super sulfated cement with a strength class 32.5N (for samples immersed in water at 20°C). These samples are always in conformity with the new European standard. For a given SSC formulation, it is noticeable that the origin of the calcium sulfate addition affects the setting and hardening phenomena. The use of heatactivated gypsum as a sulfate activator appears preferable. © (2014) Trans Tech Publications, Switzerland. Source

Phelipot-Mardele A.,Rennes1 University | Lanos C.,Rennes1 University | Gabriel S.,Rennes1 University | Baux C.,Rennes1 University
Key Engineering Materials

The purpose of this study is to evaluate the performances of Super Sulfated Cement (SSC) foams, focusing on structural, thermal and mechanical characteristics. The studied set of SSC foam samples is obtained with the same slurry. The chosen foaming method allows an interesting density variation: from 489 kg/m3 to 1793 kg/m3. Thanks to a CCD camera, the visual study of foam pore structure reveals two kinds of bubbles distribution and associated connectivity. This may partially explain the obtained thermal and mechanical behavior. Results show that SSC foams with low density (< 550 kg/m3) are usable as thermal insulator for non-loadbearing walls. Mean density SSC foams (550 kg/m3 < r < 640 kg/m3) can be used as slight-loadbearing and thermal insulating products in housing and SSC foams with high density (640 kg/m3 < ρ < 1200 kg/m3) as loadbearing products staying within lightweight class. © (2014) Trans Tech Publications, Switzerland. Source

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