Spelling suggestions: "subject:"light touch"" "subject:"might touch""
1 |
Étude du couplage entre toucher léger et posture / Investigation on the coupling between light touch and postureVérité, Fabien 12 September 2016 (has links)
Parmi toutes les informations sensorielles que le système nerveux central doit intégrer afin d'établir la commande musculaire permettant d'assurer une position debout, nous nous sommes plus particulièrement intéressés à ce qui est nommé le " toucher léger ". En effet, il a été montré que poser le doigt sur une surface fixe, même légèrement, fournissait une information supplémentaire permettant d'améliorer le contrôle postural. De manière intéressante, lorsque la surface est mise en mouvement, un couplage apparait entre ces mouvements et le balancement postural. Nous avons lors de nos travaux étudié comment cette information était intégrée au contrôle postural. En se basant sur les conclusions de cette étude, nous avons proposé une loi de commande en boucle fermée basée sur la modulation de la vitesse du doigt, qui permet de contrôler la position du centre de pression autour d'une consigne prédéfinie. Nous avons de plus étudié les conditions expérimentales pouvant affecter les performances de cette boucle fermée (instruction, conscience des mouvements du doigt, ajout/retrait d'un sens (la vision), action de rejet volontaire du couplage). Ces études nous permettent de proposer une explication exhaustive des mécanismes expliquant ce phénomène de couplage entre la posture et les mouvements du doigt. La loi de commande proposée permet de guider le centre de pression autour d'une consigne prédéfinie, tout en ne nécessitant ni la coopération ni la concentration des sujets, et présente ainsi un intérêt certain dans les domaines de l'assistance ou de la rééducation. Nous avons donc mené une étude préliminaire en milieu clinique démontrant le potentiel applicatif de cette dernière. / Among the sensory information allowing to control postural balance, we have focused our research on Light Touch. Indeed, it has been shown that lightly touching a motionless surface, provides additional sensory information that improves balance. Interestingly, when the surface is moved slowly, a coupling appears between its motion and postural sway. We have investigated the mechanisms underlying this coupling. Based on our findings, we implemented a closed-loop control law, based on the modulation of the finger velocity, which allows to control the position of the center of pressure around a pre-defined trajectory. We also studied the experimental conditions that could influence the performance of the closed loop (instruction, awareness of finger movements, adding / removing a sensory inputs (vision), voluntary dismissal of action coupling). These studies allow us to offer a comprehensive explanation of the mechanisms underlying this phenomenon of coupling between the posture and movements of the finger. The proposed control law allows to guide the center of pressure around a pre-defined trajectory, without any cooperation from the participants. It could have an interest in the areas of assistance or rehabilitation as a new biofeedback. We therefore conducted a preliminary study in a clinical environment.
|
2 |
Effects of haptic supplementation on postural stability in standing, perturbed standing and sitting in older adultsAlbertsen, Inke 14 December 2012 (has links)
Le présent travail portait sur l'étude des effets de la supplémentation haptique sur la stabilité posturale debout et assise du sujet jeune et âgé. La question si les informations haptiques fournies par un support mobile améliorent la stabilité autant qu'un support fixe a peu été étudiée. Le présent travail visait à contribuer à une meilleure compréhension des mécanismes sous-jacents à l'effet stabilisateur potentiel d'un support type « canne mobile ». Les analyses portaient sur le centre de pression (COP). Les résultats des premières deux études confirment notre hypothèse générale sur l'effet de la supplémentation haptique indépendant de l'âge et de la mobilité du support. Si une résistance suffisante est fournie à l'opposé des oscillations du corps par le support les participants amélioraient leur stabilité. Dans la troisième étude, nous avons également manipulé des entrées visuelles et les résultats suggèrent qu'un manque de vision peut être compensé par la supplémentation. Dans la quatrième étude, nous avons également analysé la coordination inter-segmentaire. Les résultats suggèrent un meilleur contrôle postural avec la supplémentation alors qu'elle n'influence pas la coordination inter-segmentaire. La cinquième étude visait à déterminer si la supplémentation permettait d'améliorer la robustesse du système à des perturbations. Les résultats suggèrent que les sujets jeunes réduisent le temps de la première correction du COP avec la supplémentation alors que les sujets âgés corrigent leur COP plus tôt que les jeunes et ne bénéficient pas de cette dernière. Les résultats expérimentaux laissent envisager l'application du paradigme « canne mobile » à la locomotion. / This work was dedicated to the study of the effects of haptic supplementation on postural stability of young and old adults during standing and sitting tasks. The question of whether haptic information provided by a mobile support improves stability similar to a fixed support has been rarely studied. The present work aimed to contribute to a better understanding of the underlying mechanisms of the potential stabilizing effect of haptic information provided by a cane-like support. The analysis focused on the center of pressure (COP). The results of the first two studies confirmed our general hypothesis about the effect of haptic supplementation independent of age and the mobility of the support. If sufficient resistance is provided by the support against body sway participants improved their postural stability. In the third study, we also manipulated visual inputs and the results suggested that a lack of vision can be compensated due to supplementation. In the fourth study, we also analyzed the inter-segmental coordination. The results suggested a better postural control due to supplementation whereas it does not affect the inter-segmental coordination. The fifth study aimed to determine whether haptic supplementation improves the system's robustness to sudden perturbations. The results suggested that only young participants reduce the time to the first COP correction due to supplementation while elderly correct the COP earlier than young adults, even without additional haptic information, and therefore do not benefit from haptic supplementation. Overall, the experimental results open the way for the application of the “mobile-stick” experimental paradigm to locomotion.
|
3 |
Beyond short-termism : effective regulatory and financial industry reform for sustainable long-term investment in publicly listed companiesWilley, Kim January 2019 (has links)
This thesis examines responses to the problem of stock market short-termism ('SMST'). SMST is defined as investors preferring short-term financial returns over potentially more profitable longer-term investment opportunities. Such short-termism may result in serious real-world consequences. Company executives appear to respond to short-term pressures in ways that jeopardize the long-term sustainability of listed companies negatively impacting investors and other stakeholders including employees, customers and the community at large. This thesis provides an original contribution to the academic literature via an in-depth examination of all significant regulatory and financial industry efforts meant to reform SMST in major capital markets after the global financial crisis of 2007-2009. I hypothesize that the extensive discussion of the SMST issue has generated substantial reforms. Based on an analysis of the implemented reforms, I reveal that the anticipated surge of SMST reform has not occurred. I then explore why the widespread SMST discussion has not resulted in greater reform efforts. This examination reveals the complex nature of the SMST problem and the evidentiary issues inherent in viably identifying and measuring the harms of SMST. However, I determine that there is probable cause for concern justifying SMST reform measures. Further, I conclude that SMST issues arise because investors are biased towards short-term returns when calculating risk. This bias is evident in share pricing, meaning that share prices are not a reliable indicator of fundamental corporate value. Based on this conclusion, an original dual pathway for SMST reform is proposed. This dual pathway indicates that SMST reform measures must either: (1) reduce the actual or perceived excessive discounting of future returns by investors (i.e. make share prices better reflective of long-term value); or (2) cut-off the transmission mechanisms of SMST into the listed company (i.e. sever the link between share prices and corporate decision-making). Assessing the reforms against this dual pathway reveals that few of the reforms are conceptually effective. Of the few reforms that are conceptually effective, most are relatively 'light' touch. A 'light' touch approach may not be problematic, however, as such measures are easier to implement than 'hard' law. In the case of regulatory reforms, a 'light' touch approach provides scope for flexibility to minimize the many potential harms associated with 'hard' law measures. Consequently, this thesis concludes that SMST reform is more likely to occur if reformers pursue a 'lighter' touch approach meant to reduce excessive discounting of future returns and 'nudge' capital markets away from their harmful short-termism focus.
|
Page generated in 0.0281 seconds