THE DYNAMICS OF LONGITUDINAL IMPACT TRANSMISSION AND ATTENUATION IN AMPUTEES RUNNING WITH BELOW-KNEE PROSTHESES

Lower limb amputees who want to stay physically active and rely on activities such as jogging to improve their fitness level often encounter limitations related to the prosthesis they are wearing. The loss of an important amount of the biological tissues attenuating the foot-ground repetitive impact shocks can possibly lead to severe health problems like cartilage degeneration, stress fractures and even be a contributing factor in the development of low back pain. Since the wearing of a prosthesis is considered to alter the overall locomotion dynamics of an individual it becomes imperative to study the different aspects of the human body response in such a situation. The present research on the longitudinal impact attenuation dynamics of amputees running with below-knee prostheses was undertaken in order to determine shock transmission phenomenons above and below the ankle and knee joints. A group of seven (7) below-knee amputees, wearing a prosthesis since two (2) years or more and exhibiting a flight phase in their running pattern, was used for the study. Five (5) trials for each leg were evaluated while running at a speed between 2.8 and 3.2 ms-1. Impact shock was measured with accelerometers placed at ankles and hips as well as with a force platform. A kinematic study of sequences filmed with three video cameras complemented the kinetic study. Results have shown that the impact shock transmitted from ankle to hip is attenuated in both the prosthetic and the sound limb, even if the materials and the mechanisms responsible for the absorbtion are different. It was also demonstrated that subjects who had attained higher running ability through the readaptation process were applying larger loads on the prosthetic limb, rather than protecting it, as many amputees do. Conclusions of the present study as well as from recent literature indicate that amputees wearing prostheses well adapted to their specific needs can effectively participate in many physical activities involving repetitive longitudinal impacts after adequate readaptation

Vaccination de volontaires sains avec le vaccin contre la fièvre jaune afin de caractériser la réponse immunitaire protectrice

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Sensitivity and vulnerability to groundwater overexploitation by a ‘pressure state impact’ and process based approach

A methodology is developed for proposing a groundwater vulnerability assessment in a Pressure-State-Impact causal chain that is familiar to decision makers. The ‘Driver Pressure State Impact Response’ (DPSIR) framework, for describing interactions between society and the environment, defines a chain of Drivers that exert Pressures on the State of a given resource, such as groundwater, which then generates an Impact that will require an appropriate Response (Kristensen, 2004). The method is here based on the calculation of sensitivity coefficients for a user-defined groundwater state for which several physically-based indicators are proposed. These sensitivity coefficients reflect the easiness with which the groundwater state transmits pressures into impacts. They are grouped into a vulnerability matrix of pressures and impacts that quantify vulnerability for every combination of causal links identified in the DPSIR chain. For that reason, the sensitivity coefficients are converted to vulnerability, using the concept of ‘transgressing a given threshold’, which is commonly used in socioeconomic sciences (Luers et al. 2003). The concept of ‘rising above a given concentration threshold’ can be used for groundwater quality issues. The concept of ‘falling below a given piezometric head threshold’ can be used for groundwater quantity issues as aquifer overexploitation problems. Outside the careful selection of the sensitivity analysis method that can significantly influence the computational effort (Beaujean et al., 2013), emphasis is given to the illustration of the general methodology on a simple groundwater quantity case (of an alluvial aquifer with concerns related to water supply) demonstrating the potential use of this general and physically based vulnerability assessment method. While the methodology is general, the choice of causal chains has to be made prior to the calculation. The vulnerability is also related to a damaged state and is related to the ‘distance’ between the current state and a given threshold. This choice is arbitrary such that the vulnerability is sensitive to the choice of the threshold

Developping a physically based groundwater vulnerability concept in a DPSIR framework

A general physically based method is presented to assess vulnerability of groundwater to external pressures with respect to quality and/or quantity issues. In the vulnerability assessments, many scientific authors agree nowadays that ‘physically based’ methods must be preferred to traditional approaches based on empirical overlay and index methods where physical attributes are often mixed with implicitly embedded conventional priorities. Results from one or another of these last methods can consequently be very dissimilar for a given case study and decision makers are losing confidence in these tools. A methodology is proposed to reframe the groundwater vulnerability assessment in a Pressure-State-Impact causal chain that is familiar to decision makers. The DPSIR framework, for describing interactions between society and the environment, defines a chain of Drivers that exert Pressures on the State of a given resource, such as water, which then generates an Impact that will require an appropriate Response (Kristensen, 2004). The concept of groundwater vulnerability assessment considered here is based on the calculation of sensitivity coefficients for a user-defined groundwater state for which several physically-based indicators are proposed. These sensitivity coefficients reflect the easiness with which the groundwater state transmits pressures into impacts. They are grouped into a vulnerability matrix of pressures and impacts that quantify vulnerability for every combination of causal links identified in the DPSIR chain. For that reason, the sensitivity coefficients are converted to vulnerability, using the concept of ‘falling below a given threshold’, which is commonly used in socioeconomic sciences (Luers et al. 2003). Outside the careful selection of the sensitivity analysis method that can significantly influence the computational effort (Beaujean et al., 2013), emphasis will be given to the illustration of the general methodology on a simple case (of an alluvial aquifer with concerns related to water supply) demonstrating the potential use of this general and physically based vulnerability assessment method. While the methodology is general, the choice of causal chains has to be made prior to the calculation. The vulnerability is also related to a damaged state and is related to the ‘distance’ between the current state and a given threshold. This choice is arbitrary such that the vulnerability is sensitive to the choice of the threshold. The framework is general and, when applied to water, can include states that are not limited to quality such as, for example, water quantity and availability

Identification Des Zones Potentielles De Recharge Des Aquifères Fracturés Du Bassin Versant Du N’zo (Ouest De La Côte d’Ivoire) : Contribution Du SIG Et De La Télédétection

In a watershed one of the most important data is recharge because it is the main groundwater supply. Recharge is however, a difficult parameter to calculate due to its variability. The objective of this study is to propose a method of identifying potential recharge zone which is applicable to large watersheds. The study area is the N’zo watershed located in the West of Côte d’Ivoire. It covers an area of 4,300 km2 . The water supply of the population is essentially ensured by the fractured aquifers which are the regional aquifers.The data used in this study are classified in two groups1) the cartographic data are composed of geological soil and drainage maps; and 2) data from remote sensing which consist of slope, land use and fractures maps. These data are combined through a multi-criteria analysis to facilitate spatial analysis and identification of potential recharge areas. The results indicate that potential areas of high recharge account for about 20% of the total watershed area. They are mainly located in the south and center and appear fragmented in the north of the watershed