Assessment of the risk and biomechanical consequences of lateral epicondylalgia by estimating wrist and finger muscle capacities in tennis players

Previous studies suggested that a pronounced weakness of the extensor muscles relative to the flexor muscles could increase the risk of occurrence of lateral epicondylalgia. This study investigates this hypothesis by estimating the ratio of extensor to flexor muscle capacities among healthy non-players (n = 10), healthy tennis players (n = 20), symptomatic players (n = 6), and players who have recovered from lateral epicondylalgia (n = 6). Maximum net joint moments in flexion or extension were measured during seven tasks involving the voluntary contraction of wrist and fingers. Using these data, the muscle capacities of the main muscle groups of the hand (wrist flexors, wrist extensors, finger flexors, finger extensors, and intrinsic muscles) were estimated using a musculoskeletal model. These capacities were then used to compute the extensor/flexor capacity ratios about the wrist and the finger joints. Compared to healthy non-players, healthy players presented higher extensor muscle capacities and greater capacity ratios showing that playing tennis generates specific adaptations of muscle capacities. Interestingly, symptomatic players, similar to those of non-players, showed more imbalanced ratios than healthy players. These results confirm that the ratio of extensor/flexor muscle capacities seems to be associated with lateral epicondylalgia and can be further used to understand its incidence and consequences.     

Formation d'Ingénieurs en Génie Sanitaire: un exemple de collaboration entre deux universités

For eight years, the Federal Institute of Technology of Lausanne (EPFL), Switzerland and the Ecole Inter-Etats d'Ingénieurs de I'Equipement Rural (EIER) at Ouagadougou Burkina Faso, have collaborated in the postgraduate education and training of university engineers, offering a course in Sanitary Engineering, comprising 8 months in Ouagadougou, followed by 3 months in Lausanne. Successful students receive a diploma confered by the two Engneering Schools. Such collaboration is productive only if planned on a long-trem basis forcing some of the limiting principles of technical development programmes to be sidestepped. The better students may continue their studies towards an MSc or a PhD, developing the EIER's research facilities, working on topics directly related to Afircan needs and may benefit fiom EPFL's facilities and scientific experience.     

Academic self-concept,autonomous academic motivation,and academic achievement: Mediating and additive effects

Three conceptual models were tested to examine the relationships among academic self-concept, autonomous academic motivation, and academic achievement. This allowed us to determine whether 1) autonomous academic motivation mediates the relation between academic self-concept and achievement, 2) academic self-concept mediates the relation between autonomous academic motivation and achievement, or 3) both motivational constructs have an additive effect on academic achievement. A total of 925 high school students (404 boys and 521 girls) were asked to complete a questionnaire on two occasions separated by a year interval. Results from SEM analyses provided good support for the hypothesized model positing that autonomous academic motivation mediates the academic self-concept–academic achievement relation. Results are discussed in light of self-determination theory and self-concept theory.     

Development of SMEs and heterogeneity of trajectories: the case of biotechnology in France

Biotechnology is an emergent sector based on the creation of research-intensive Small and Medium Enterprises (SMEs). While some SMEs are growing, most of them remain small, even those set-up several years ago. What is the pattern of development of the biotech sector? What are the patterns of development of firms? Studies on the development of high-tech SMEs have focused on a business model, in which entrepreneurs rely on growth forecasts to persuade capital investors (business angels and venture capitalists) to invest in a radical innovation project. Firms aim for a world market to industrialise their innovation, and initial public offering (IPO) enables initial investors to make profits that offset risky initial investment. While this model is appealing, it is simply one of the possible models of biotechnology development. Some firms are not designed to experience exponential growth, and choose to target local markets. Moreover, not all firms have the ambition of being listed on the stock exchange. Based on an in-depth analysis of the business and development of 60 French biotech SMEs, this article identifies two business models. By defining the development trajectories of each of these models, it highlights the temporary nature of the emergent model.     

Finite Memory Observers for linear time-varying systems. Part II: Observer and residual sensitivity

Fault detection and diagnosis are important issues in process engineering. Hence, considerable interest is growing in this field from industrial practitioners as well as academic researchers, as opposed to 30 years ago. This paper focusses on a model-based approach for fault detection. This approach is based on Finite Memory Observers (FMO), properties of this observer are presented in the first part of our work (Graton et al., 2014 [1]), the main results of this paper are recalled at the beginning of this paper and constitute the basis of this second part. Properties of the Finite Memory Observer (FMO) are studied from a global point of view for the class of linear time-varying (LTV) systems with stochastic noises. FMO performances take their framework from the study of their properties, and from the study of their influences on diagnosis results. Fundamentally, the generation of residuals is essential in a diagnosis procedure. In Graton et al. (2014) [1], the design for the finite memory observer is shown, the determination of its optimal window length is solved, and the generation of residuals for diagnosis is completed. This paper is the second part of this work and is devoted to the study of the observer and residual sensitivity towards model parameter variations and noises.     

Three-dimensional kinematics of the lower limbs during forward ice hockey skating

The objectives of the study were to describe lower limb kinematics in three dimensions during the forward skating stride in hockey players and to contrast skating techniques between low- and high-calibre skaters. Participant motions were recorded with four synchronized digital video cameras while wearing reflective marker triads on the thighs, shanks, and skates. Participants skated on a specialized treadmill with a polyethylene slat bed at a self-selected speed for 1 min. Each participant completed three 1-min skating trials separated by 5 min of rest. Joint and limb segment angles were calculated within the local (anatomical) and global reference planes. Similar gross movement patterns and stride rates were observed; however, high-calibre participants showed a greater range and rate of joint motion in both the sagittal and frontal planes, contributing to greater stride length for high-calibre players. Furthermore, consequent postural differences led to greater lateral excursion during the power stroke in high-calibre skaters. In conclusion, specific kinematic differences in both joint and limb segment angle movement patterns were observed between low- and high-calibre skaters.     

A comparison of lactate indices during ramp exercise using modelling techniques and conventional methods

Abstract

The aim of this study was to compare the lactate indices provided by single- and double-breakpoint models with lactate thresholds obtained with conventional methods. Arterial samples for the determination of lactate concentrations were drawn from eight participants at rest and every minute during a ramp test (15 W · min^?1) on a cycle ergometer. Lactate thresholds were determined from a blood lactate concentration equal to 4 mM (LT₄), from an increase of 1 mM above the resting level (Δ1 mM), and from indirect methods using ventilatory parameters. Other indices were computed from the modelling of the lactate curve using an exponential function (LSI), a polynomial function (Dmax), a semi-log model (SLog), a parabola plus delay model (Mod P), and a two-breakpoint model (Mod M). Mod P and Mod M showed poor agreement with the other methods. LT₄, Dmax, LSI, and respiratory exchange ratio equal to 1 were correlated with each other (0.81 ≤ R ≤ 0.92) and their mean differences ranged from 2.8 to 15 W, with limits of agreement within the range ± 24.6 to ± 42.4 W. These results question the interest in breakpoints models to detect lactate thresholds, knowing that LT₄, LSI, Dmax, and respiratory exchange ratio equal to 1 provide indices that occur at similar power outputs.