Effects of climate change on high Alpine mountain environments: Evolution of mountaineering routes in the Mont Blanc massif (Western Alps) over half a century

International audienceIn high alpine environments, glacial shrinkage and permafrost warming due to climate change have significant consequences on mountaineering routes. Few research projects have studied the relationship between climate change and mountaineering; this study attempts to characterize and explain the evolution over the past 40 years of the routes described in The Mont Blanc Massif: The 100 Finest Routes, Gaston Rébuffat's emblematic guidebook, published in 1973.The main elements studied were the geomorphic and cryospheric changes at work and their impacts on the itinerary's climbing parameters, determining the manner and possibility for an itinerary to be climbed. Thirty-one interviews, and comparison with other guidebooks, led to the identification of 25 geomorphic and cryospheric changes related to climate change that are affecting mountaineering itineraries. On average, an itinerary has been affected by nine changes. Among the 95 itineraries studied, 93 have been affected by the effects of climate change-26 of them have been greatly affected; and three no longer exist. Moreover, periods during which these itineraries can be climbed in good conditions in summer have tended to become less predictable and periods of optimal conditions have shifted toward spring and fall, because the itineraries have become more dangerous and technically more challenging

Delayed postural control during self-generated perturbations in the frail older adults

International audiencePurpose: The aim of this study was to investigate the coordination between posture and movement in pathological aging (frailty) in comparison with normal aging, with the hypothesis that in pathological aging, postural control evolves towards a more reactive mode for which the perturbation induced by the movement is not anticipated and leads to delayed and late postural adjustments. Methods: Elderly subjects performed rapid focal arm-raising movements towards a target, from an upright standing position in two stimuli conditions: simple reaction time and choice reaction time (CRT). Hand and center of pressure (CoP) kinematics were compared between a control group and a frail group of the same age. Results: In frail individuals, the entire movement was impaired and slowed down. In addition, postural adjustments that classically precede and accompany the focal arm movement were delayed and reduced, especially in the CRT condition in which the motor prediction is more limited. Finally, a correlation between the time to CoP maximal velocity and the timed up-and-go score was observed. Conclusion: In these patients, it was concluded that the control of the CoP displacement evolved from a proactive mode in which the perturbation associated with the arm movement is anticipated toward a more reactive mode in which the perturbation is compensated by late and delayed adjustments

An Art-Based, Collective and Dialogic Ethnographic method -Unveiling corporate restructuring practices

Restructuring practices belong to today's organizational life. Even if the phenomenon is not new it significantly evolved over time, both in terms of motives and in terms of expressions, from major events to permanent practices, from crisis to competitiveness restructurings, from reactive to more proactive decisions, from highly visible to more silent decisions. Much debated in popular medias, restructuring issues have been also inspiring scholars from various fields (sociology, economics, management, law...) for now three decades. But at the same time, academic literature, especially in management, has hardly contributed in understanding the deep complexity and the multiple hidden dimensions of restructuring situations. We suggest ethnographic studies could open the " black box " of restructuring issues, thus complementing the inevitably over-simplified models testing the explanatory relationships between a set of variables or constructs. Traditional ethnographic method is scarcely chosen by scholars analyzing restructuring issues, mainly for reasons related to practical access to fieldwork: restructuring is a hot issue, and it remains difficult to access information and informants in a restructuring organization. In order to overcome these issues, we developed a specific research method what we call an Art-Based, Collective and Dialogic Ethnographic method (1.), both in its deliberate choices (1.1.) and its emergent dimensions (1.2.). Then we describe the outputs of the method (2.), in terms of creating new knowledge about restructuring issues (2.1.), but also in terms of fostering new ways of teaching, thinking or practicing restructurings (2.2.). In the final section, we discuss the basic principles of the method as well as its outcomes, especially in terms of creating "vicarious experiential knowledge" (3.). This method is based on three main features. First, we suggest investigate restructuring issues through artworks. Second, as restructurings are multi-actor situations and multi-dimensional phenomena, research on restructurings could benefit from a heterogeneous and multi-disciplinary group of actors as a community of inquirers confronting their points of view and reflecting together about the complexity and the heterogeneity of restructuring phenomena in a dialogical process of investigation. Third, combining in the same research design a heterogeneous group of actors and a series of artworks about restructurings can lead to innovative research methods: collective comments about artworks and indirect analysis of restructuring, reflexive analysis of actors' involvement, comments and discussions used as data, what we propose here as a new form of organizational ethnographic research

Balance control in aging: improvements in anticipatory postural adjustments and updating of internal models

International audiencePostural stability of older subjects can be estimated during orthostatic equilibrium. However, dynamic equilibrium is also important to investigate risks of fall. It implies different interpretations of measures given by force plates. Same dependant variables (e.g. center of pressure displacement) cannot be interpreted the same ways depending of the type of equilibrium that is investigated. In particular, sways increases during dynamic equilibrium and before movement execution may reflect an improvement of feedforward control

Direct measurement of dynamical membrane permeabilities, under maintained non-equilibrium conditions

The study of membrane phenomena by means of the Thermodynamics of Irreversible Processes led us to define the dynamical membrane permeability. The latter results from diffusion phenomena and intramembrane chemical reactions. The experimental device presented here was elaborated in order to bring a membrane system into an ionic gradient maintained constant. This gradient is obtained by independent control of the concentrations of both its bounds. The actual transmembrane flux and the dynamical permeability are deduced from the direct measurement of artificial exchanges between the system and the environment. Some representative results are gathered at the end of the paper; they relate to cellulose membranes bearing ATPase and to membranes made of albumin reticulated with the visual pigment rhodopsin

Motor-prediction improvements after virtual rehabilitation in geriatrics: Frail patients reveal different learning curves for movement and postural control

International audienceBackground. - Postural control associated with self-paced movement is critical for balance in frail older adults. The present work aimed to investigate the effects of a 2D virtual reality-based program on postural control associated with rapid arm movement in this population. Methods. - Participants in an upright standing position performed rapid arm-raising movements towards a target. Practice-related changes were assessed by pre- and post-test comparisons of hand kinematics and centre-of-pressure (CoP) displacement parameters measured in a training group and a control group. During these pre- and post-test sessions, patients have to reach towards yellow balls appearing on the screen, form a standardized upright position (with 15 cm between the two malleoli). Training group patients took part in six sessions of virtual game. In this, patients were asked to reach their arm towards yellow balls appearing on the screen, from an upright position. Results. - After training, we observed improvements in arm movements and in the initial phase of CoP displacement, especially in the anticipatory postural adjustments. Learning curves for these two types of motor improvements showed different rates. These were continuous for the control of the arm movement, and discontinuous for the control of the CoP during the anticipatory postural adjustments. Conclusion. - These results suggest that some level of motor (re)-learning is maintained in frail patients with low functional reserves. They also suggest that re-learning of anticipatory postural control (i.e. motor prediction) is less robust than explicit motor learning involved for the arm reaching. This last point should encourage clinicians to extend the training course duration, even if reaching movement improvements seems acquired, in order to automate these anticipatory postural activities. However, other studies should be done to measure the retention of these two types of learning on a longer-term period. (c) 2013 Elsevier Masson SAS. All rights reserved

Practice-Related Improvements in Postural Control During Rapid Arm Movement in Older Adults: A Preliminary Study

International audienceBackground. Postural control associated with self-paced movement is critical for balance in older adults. The present study aimed to investigate the effects of a virtual reality based program on the postural control associated with rapid arm movement in this population. Methods. From an upright standing position, participants performed rapid arm raising movements toward a target. Practice-related changes were assessed by pre- and posttest comparisons of hand kinematics and center of pressure displacement parameters measured in a training group (mean age: 71.50 +/- 2.67 years, n = 8) and a control group (mean age: 72.87 +/- 3.09 years, n = 8). Training group participants took part in six sessions (35-40 minutes per session, three sessions per week). During the two test sessions, arm raising was analyzed under two conditions of stimuli: choice reaction time and simple reaction time. Results. We observed improvements in the arm movement after training under both conditions of stimuli. The initial phase of the center of pressure displacement, especially the anticipatory postural adjustments, was improved in the choice reaction time condition. Conclusions. Our short training program resulted in motor optimization of the postural control associated with rapid arm movements, and this implies central changes in motor programming