1,017 research outputs found

    Using an electrohydraulic ankle foot orthosis to study modifications in feedforward control during locomotor adaptation to force fields applied in stance

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    BACKGROUND: Adapting to external forces during walking has been proposed as a tool to improve locomotion after central nervous system injury. However, sensorimotor integration during walking varies according to the timing in the gait cycle, suggesting that adaptation may also depend on gait phases. In this study, an ElectroHydraulic AFO (EHO) was used to apply forces specifically during mid-stance and push-off to evaluate if feedforward movement control can be adapted in these 2 gait phases. METHODS: Eleven healthy subjects walked on a treadmill before (3 min), during (5 min) and after (5 min) exposure to 2 force fields applied by the EHO (mid-stance/push-off; approximately 10 Nm, towards dorsiflexion). To evaluate modifications in feedforward control, strides with no force field ('catch strides') were unexpectedly inserted during the force field walking period. RESULTS: When initially exposed to a mid-stance force field (FF 20%), subjects showed a significant increase in ankle dorsiflexion velocity. Catches applied early into the FF 20% were similar to baseline (P > 0.99). Subjects gradually adapted by returning ankle velocity to baseline over approximately 50 strides. Catches applied thereafter showed decreased ankle velocity where the force field was normally applied, indicating the presence of feedforward adaptation. When initially exposed to a push-off force field (FF 50%), plantarflexion velocity was reduced in the zone of force field application. No adaptation occurred over the 5 min exposure. Catch strides kinematics remained similar to control at all times, suggesting no feedforward adaptation. As a control, force fields assisting plantarflexion (-3.5 to -9.5 Nm) were applied and increased ankle plantarflexion during push-off, confirming that the lack of kinematic changes during FF 50% catch strides were not simply due to a large ankle impedance. CONCLUSION: Together these results show that ankle exoskeletons such as the EHO can be used to study phase-specific adaptive control of the ankle during locomotion. Our data suggest that, for short duration exposure, a feedforward modification in torque output occurs during mid-stance but not during push-off. These findings are important for the design of novel rehabilitation methods, as they suggest that the ability to use resistive force fields for training may depend on targeted gait phases

    Energy-QoS Tradeoffs in J2EE Hosting Centers

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    International audienceNowadays, hosting centres are widely used to host various kinds of applications e.g., web servers or scientific applications. Resource management is a major challenge for most organisations that run these infrastructures. Many studies show that clusters are not used at their full capacity which represents a significant source of waste. Autonomic management systems have been introduced in order to dynamically adapt software infrastructures according to runtime conditions. They provide support to deploy, configure, monitor, and repair applications in such environments. In this paper, we report our experiments in using an autonomic management system to provide resource aware management for a clustered application. We consider a standard replicated server infrastructure in which we dynamically adapt the degree of replication in order to ensure a given QoS while minimising energy consumption

    Effects of Dietary Palm Oil on the Whole-Body Mineral Composition of African Catfish, Heterobranchus longifilis (Teleostei, Clariidae)

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    A 50-day feeding trial was carried out to determine the effect of the graded incorporation of crude palm oil on the whole-body mineral composition of African catfish juveniles Heterobranchus longifilis. Six diets were formulated to contain from 3–21% crude palm oil (CPO). Whole-body macromineral composition represented by calcium (Ca), potassium (K), sodium (Na), phosphorus (P) and magnesium (Mg) showed significant variations (p < 0.05) with the different dietary palm oil levels. The same trend was observed in whole-body micromineral composition in iron (Fe), zinc (Zn), manganese (Mn) and copper (Cu). Regardless of the micromineral, the increase in the body was related with increasing dietary palm oil levels between 3 and 9%. In summary, the results of this study suggest that an incorporation of palm oil into the fish diet modifies the mineral body composition without major effects on health and nutritional quality of fish

    Dimorphisme sexuel et caractĂ©risation biomĂ©trique de la SĂ©riole guinĂ©enne, Seriola carpenteri, (Mather 1971) Ă©chantillonnĂ© dans la Zone Economique Exclusive (ZEE) de la CĂŽte d’Ivoire

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    La reproduction artificielle des poissons en captivitĂ© nĂ©cessite la connaissance de leur dimorphisme sexuel. La dĂ©termination du dimorphisme sexuel de la SĂ©riole GuinĂ©enne, Seriola carpenteri est difficile Ă  travers l'examen de l'orifice urogĂ©nital. Cette Ă©tude a pour but de dĂ©terminer le dimorphisme sexuel et les caractĂ©ristiques biomĂ©triques chez Seriola carpenteri (Mather, 1971) Ă©chantillonnĂ©e dans la Zone Économique Exclusive (ZEE) ivoirienne, dans le Golfe de guinĂ©e. Ainsi, un Ă©chantillonnage de 360 spĂ©cimens de Seriola carpenteri (Mather, 1971) encore appelĂ© SĂ©riole guinĂ©enne a Ă©tĂ© effectuĂ© en raison de 30 individus par mois pendant la pĂ©riode allant d’aoĂ»t 2017 Ă  juillet 2018. Le poids et la longueur standard des spĂ©cimens variaient respectivement de 300,2 g Ă  935 g et de 22,8 cm Ă  36,2 cm. L’étude biomĂ©trique basĂ©e sur les caractĂšres morphomĂ©triques et mĂ©ristiques n’a enregistrĂ© de difference significative et ont rĂ©vĂ©lĂ© une allomĂ©trie minorante de la relation taille-poids et une isomĂ©trie de relation pour l’essentiel des paramĂštres linĂ©aires par rapport Ă  la longueur standard (LS). Par ailleurs, les relations morphomĂ©triques chez la sĂ©riole guinĂ©enne ont montrĂ© que la vitesse de croissance de la longueur standard est plus rapide que la vitesse de la croissance des paramĂštres linĂ©aires. Cette Ă©tude a montrĂ© qu’il n’existe aucun dimorphisme sexuel chez la sĂ©riole guinĂ©enne dans la ZEE ivoirienne.Mots clĂ©s : Dimorphisme sexuel, BiomĂ©trie, Seriola carpenteri, ZEE, CĂŽte d’Ivoire

    LIG-AIKUMA: a Mobile App to Collect Parallel Speech for Under-Resourced Language Studies

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    International audienceThis paper reports on our ongoing efforts to collect speech data in under-resourced or endangered languages of Africa. Data collection is carried out using an improved version of the An-droid application (AIKUMA) developed by Steven Bird and colleagues [1]. Features were added to the app in order to facilitate the collection of parallel speech data in line with the requirements of the French-German ANR/DFG BULB (Breaking the Unwritten Language Barrier) project. The resulting app, called LIG-AIKUMA, runs on various mobile phones and tablets and proposes a range of different speech collection modes (recording , respeaking, translation and elicitation). It was used for field data collections in Congo-Brazzaville resulting in a total of over 80 hours of speech
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