Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

When vestibular sense organs suffer damage functional problems arise such as imbalance and falls as well as difficulty with gaze control, resulting in blurred vision, dizziness and feelings of disorientation. A novel computer-based rehabilitation program has been developed. Using the Gyration TM motion-sense mouse, attached to a headband, to control computer applications and games, the participants were able to interact with targets in computer games through head motion, allowing different gaze exercises to be carried out. Balance exercises can be incorporated simultaneously and progressively into the rehabilitation program. The main findings of this study revealed that using head rotation to interact with computer games coupled with demanding balance conditions resulted in substantial improvements in gaze control, standing balance and walking performance. These observations provide support that a low-cost home computer-gaming rehabilitation program is well suited to train gaze control through active and passive head motion and to concomitantly train standing balance.

South Africa is a water scarce country. As pressure on available water resources increases, irrigation, the largest consumer of water, has to find ways of improving water use efficiency. Benchmarking in the irrigation sector has been identified as a suitable technique to implement this improvement. Benchmarking can be broadly defined as the identification and application of organisation specific best practices with the goal of improving competitiveness, performance and efficiency. A South African sugarcane irrigation scheme was identified to investigate a proposed benchmarking methodology. The scheme was unique in that electromagnetic flow meters were utilised and monitored on a daily basis. This facilitated an in depth study into irrigation water use at the scheme. The project focused on three different objectives. The first objective was to determine the losses, and consequently the efficiency, with which the irrigation scheme was able to deliver irrigation water from the water source to the farm boundary during the years 2004 and 2005. This was achieved by completing the water balance for the scheme with specified geographic and temporal boundaries. Results indicated that the scheme was very efficient with a delivery efficiency of 83.4 and 94.0 % for 2004 and 2005 respectively. These efficiencies were above the accepted South African Department of Water Affairs and Forestry (DWAF) standard of 80 %. The temporal distribution of the delivery efficiency was also investigated to identify periods within each year when inefficiencies occurred, and to better understand the nature of potential losses. It was concluded that the investigations into the temporal distributions be utilised together with the water balance approach in future studies into the performance of irrigation water delivery infrastructure at other South African irrigation schemes. The second objective was to calculate a set of internationally applied external irrigation benchmarking indicators. External indicators from the International Water Management Institute (1WMI), the International Program for Training and Research in Irrigation and Drainage (IPTRID) and the Irrigation Training and Research Center (ITRC) were reviewed for application in a South African context. The external indicator analysis highlighted that at a scheme level, insufficient irrigation was occurring to effectively meet the irrigation demand. It was also found that the scheme infrastructure was not the limiting cause of this observation. The external indicator results highlighted the need for additional schemes for comparison purposes. The results from this component of the study also emphasized the importance of stakeholder confidentiality concerns when attempting to implement a benchmarking initiative. The third objective was to rank individual farm performance of all the farms in the scheme, in terms of total farm sugarcane yield and seasonal irrigation water use. Farm yield and irrigated area were obtained to investigate the relationships between yield and irrigation water application. There were substantial variations in total farm yield and water use for both the 2004 and 2005 seasons, indicating much potential for improvement by many farmers relative to each other. The individual seasonal farm water use was also compared to a simulated irrigation demand, as determined with the SAsched irrigation systems and crop yield model. Simulation results with the SAsched model, using representative soils and climate data for the scheme, showed that the majority of farms were under irrigating relative to the simulated demands, especially in the late spring/early summer period. From on-farm irrigation system evaluations that were performed, it was found that irrigation system capacity constraints were not limiting irrigation applications in the majority of farms. Further research in the form of selected soil water monitoring is required to investigate these observations further. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2007.

The purposes of this study were to: 1) evaluate the effect of walking speed on gait, balance and cognitive task performance and 2) examine the effect of dual task (cognitive load) on gait balance and cognitive task performance. Twenty young healthy adults (24+6 years of age) were recruited and each participant walked on a motorised treadmill at two speeds(0.5m/s and 0.8m/s), first without performing cognitive tasks, then while performing three types of cognitive loaded tasks. The speed had a significant effect on average and coefficient of variation of temporal gait parameters (P<0.001), cognitive task performance (P<0.001) and center of pressure excursion (P<0.001). No statistically significant effect of speed was found ML trunk displacement. However, dual task (cognitive load) had significant effect on COV of temporal gait (P<0.001), cognition (P<0.001) and trunk motion (P<0.001). In conclusion, the speed and dual task had significant effect on locomotors rhythm, balance, and cognitive performances.

Constraint-based models of metabolism seldom incorporate capacity constraints on intracellular fluxes due to the lack of experimental data. This can sometimes lead to inaccurate growth phenotype predictions. Meanwhile, other forms of data such as fitness profiling data from growth competition experiments have been demonstrated to contain valuable information for elucidating key aspects of the underlying metabolic network. Hence, the optimal capacity constraint identification (OCCI) algorithm is developed to reconcile constraint-based models of metabolism with fitness profiling data by identifying a set of flux capacity constraints that optimally fits a wide array of strains. OCCI is able to identify capacity constraints with considerable accuracy by matching 1,155 in silico-generated growth rates using a simplified model of Escherichia coli central carbon metabolism. Capacity constraints identified using experimental fitness profiles with OCCI generated novel hypotheses, while integrating thermodynamics-based metabolic flux analysis allowed prediction of metabolite concentrations.

Background: The relationship between eating frequency (EF) and adiposity is surrounded by controversy. Numerous cross-sectional studies have been performed on the subject, yet the results are mixed. While some of these studies show an inverse relationship between EF and adiposity, this is likely due to underreporting of EF and total energy intake when diets are self-reported. In studies where underreporting was taken into account, EF is positively associated with both energy intake and adiposity. Intervention trials have failed to show a significant effect of EF on energy intake or weight change, but only a small number exist. Objective: In this study, we examined associations among EF, energy intake, and adiposity in free living adults consuming self-selected diets. In conducting this analysis, two common methodological problems in this research area were addressed: 1) the lack of consideration of energy balance fluctuations throughout the day, and 2) a tendency not to account for implausible reporting of energy intake. We hypothesized that individuals with higher EF would have higher BMI, percentage body fat, and energy intake. Additionally individuals with greater fluctuations in energy balance will have higher BMI, percentage body fat, and EF. Methods: We performed a secondary analysis of data collected as part of a previous study in our laboratory on diet and energy regulation (unpublished). One hundred and twenty-six participants were enrolled (62.4 % female, and 75.2% Caucasian), and one participant dropped the study due to pregnancy. Mean ±SD age, BMI, and percentage body fat of the remaining 125 participants were 29.8 ±12.2 years, 24.5±3.9 kg/m2, and 27.8±9.8% respectively. We analyzed one day of dietary intake collected using a multiple pass 24 hour recall. Energy intake was calculated by NDS (Nutrition Data System for Research, version 2011 (n=36) and version 2010 (n=89)). An eating occasion was defined as any occurrence of energy intake > 0 kcal separated by at least 1 hour. EF was defined as the number of eating occasions per day. A specifically designed spreadsheet that generates within-day energy balance was used to produce estimates of hourly energy balance. We also used total energy expenditure measured by doubly labeled water and the Huang et al. (2005)1 method to identify implausible reporters (cutoff for plausibility was reported energy intake (REI) within ±16.8% of TEE) and conducted Pearson’s correlations and regression analysis in both the total sample and a subsample in which implausible energy intake reporters were excluded from analysis. Results: We identified 59.2% of the sample as implausible reporters (n=74; 47 under-reported and 27 over-reported). Mean ±SD EF and energy intake were 4.7±1.5 and 2356±964 kcal in the total sample and 4.8±1.6 and 2371±689 kcal in the plausible sample. In the total sample EF was positively correlated to energy intake among women (r=0.244, p=0.032). No other significant relationships were observed between EF and either energy intake, BMI, or percentage body fat, in the total or plausible sample. In the total sample, maximum energy deficit > 400 kcal in a 24 hours period was significantly and positively correlated with percentage body fat (r=0.211,p=0.019) and negatively correlated with EF (r=-0.243, p=0.007) when controlling for sex and age. Separating the sample by sex we observed significant positive correlation between percentage body fat and maximum energy deficit in men (r=0.382, p=0.009) but not in women. No significant relationships between fluctuations in energy balance and percentage body fat were observed in the plausible sample. Conclusion: No evidence was found to suggest a relationship between EF and adiposity. The significant positive relationships observed between maximum energy deficit and adiposity in the total sample are consistent with previous findings. The number of implausible reporters identified in our analysis supports that over and under-reporting is a major issue associated with self-reporting of dietary intake.

This study investigated dual-task processing in younger and older adults using a psychological refractory period procedure. The first task was to name the color framing a picture; the second task was to either press a button or tilt their body in the direction of the tilt of the picture. In the body-tilt condition, electromyography was used to determine the reaction time. The stimulus-onset asynchrony (SOA) between the onset of the color and tilting of the picture varied from 50 to 1000 ms. In contrast with the response selection bottleneck model, which claims that processing of a second task cannot be completed until the first task is finished, the mode of response for the two tasks directly impacted the ability to avoid the bottleneck. In the body-tilt condition the increase in reaction time to the second task with decreasing SOA was less than in the button press condition, suggesting that processing of the second task could begin before processing of the first task was completed. This was true for both younger and older adults. Contrary to previous findings that older adults cannot engage in simultaneous processing of two tasks, evidence was found that older adults, like younger adults, could bypass the cognitive bottleneck if the second task has a reflexive component.

New Zealand is both an Annex I Party to the UNFCCC, and an Annex B country of the Kyoto Protocol. By ratifying the latter, NZ has committed to reduce greenhouse gas emission to 1990 levels. The country should take domestic actions and can also use any of the Kyoto Protocol flexible mechanisms. Afforestation and reforestation on low carbon density land has been recognised as a carbon sink and hence a possible mitigation option for climate change. The current situation for New Zealand is that at least over the first commitment period (2008-2012) the country is in deficit, because emissions have continued to grow over the 1990 level, there is an increase in the deforestation rate and lower rates of new planting. The objective of this study is to analyse the potential of the New Zealand forest sector as an integrated system to mitigate climate change. It also analyses the impact of different mechanisms on potential area of new land planting, management of stands, and the supply, allocation, and demand of wood, and wood products. The New Zealand forest industry carbon balance (i.e net atmospheric exchange minus emissions) is modelled for different national estate scenarios, log allocation of harvested volume and residues used for bioenergy. The net present value of these scenarios is estimated and the economic viability assessed. The level of incentives needed to increase the returns to an economically viable level is estimated in term of carbon unit value ($/tC). Moreover the land use economics at a project level (land market value vs land expectation value) is assessed. Incentives needed in monetary terms and carbon value are also estimated. The implications of discounting carbon benefits are discussed. It was found that the carbon balance of the whole industry should be analysed for policy development on climate change mitigation options. New planting, longer rotation ages, avoiding deforestation, and allocating additional harvested volume to sawmills showed positive impact to the atmosphere. New planting appeared to be not economically viable, thus incentives are needed. It is acknowledged that, there are emissions from the sector that were not included, and that data and models used need further research to improve the accuracy of the results. Moreover, assumptions on the economic issues and an analysis of simultaneous implementation of more than one mitigation option would also improve the results.

Strukturomvandlingen till dagens tjänsteekonomi och den ökade spridningen av informations- och kommunikationsteknologi, har möjliggjort ett arbetsliv med flexibla arbetstider och arbetsplatser. Flexibelt arbete kan vara en frihet som skapar möjligheter att uppnå en bättre balans mellan arbete och övrigt liv, men det kan också vara en risk som leder till ökad stress då förhållandet mellan arbete och övrigt liv upplevs som gränslöst. Syftet med studien var att undersöka till vilken grad tjänstemän i den privata sektorn upplever att de har möjlighet att arbeta flexibelt tids- och rumsmässigt, samt om möjligheten att själv bestämma när och var man utför sitt arbete kan bidra till mindre stress och en bättre balans mellan arbete och övrigt liv. Resultatet bygger på data från en arbetsmiljöenkät inom ramen för ett treårigt forskningsprojekt vid Stockholms universitet, där gränsdragning, flexibilitet och balans i livet i förhållande till stress och hälsa var i fokus (AFA Försäkring 2015). Enkäten besvarades av 1918 tjänstemän. Variablerna som användes i studien var grad av kontroll över flexibilitet i relation till upplevd stress, upplevd balans mellan arbete och övrigt liv samt andra arbets- och familjerelaterade faktorer. Data analyserades med multipel linjär regressionsanalys. I regressionmodell 1 kontrollerades vilken effekt upplevd flexibilitet och andra arbets- och familjerelaterade faktorer hade på upplevd stress. Modellen var signifikant och kunde förklara 37,8 procent av variansen avseende upplevd stress. I regressionmodell 2 kontrollerades effekten av upplevd flexibilitet och andra arbets- och familjerelaterade faktorer på upplevd konflikt mellan arbete och övrigt liv. Modellen var signifikant och kunde förklara 39,4 procent av variansen avseende upplevd konflikt mellan arbete och övrigt liv. Resultatet visade att upplevd flexibilitet har signifikant effekt på upplevd stress (b=-,026*). Det betyder att ju högre flexibilitet tjänstemännen upplever, desto mindre stressade känner de sig. Resultatet visade även att upplevd flexibilitet inte har betydelse för upplevd balans mellan arbete och övrigt liv. Att tjänstemännen själva kan välja när och var de utför ditt arbete, leder således inte till en bättre balans mellan arbete och övrigt liv.

Syftet med denna undersökning är att få en ökad kunskap om hur HR-medarbetare lyckas förena arbete med fritid i kombination med deras flexibla arbetstider. Då HR-enheten dagligen arbetar med individer som befinner sig i olika faser i livet är det intressant att se hur de hanterar sina egna förhållanden i vardagen, arbetet och fritiden. Orsaken till att obalans uppstår beror oftast på att arbetslivet invaderar på fritiden vilket leder till att individen har mindre ork över till andra aktiviteter efter arbetstid. Att få balans handlar om individens förutsättningar att kunna hantera ett flexibelt arbete och krav utifrån, men även individens egna strategier för att uppnå balans har betydelse i sammanhanget. Då ämnet ”work-life balance” inte är fullständigt för att uppnå syftet med undersökningen har vi även valt att lägga till områden som flexibilitet, tillgänglighet och stress i vår studie. Vi har valt en kvalitativ datainsamlingsmetod och intervjuat tio medarbetare på en HR-avdelning. De variabler vi ansåg ha betydelse för undersökningen är en någorlunda jämn könsfördelning samt medarbetarnas olika ansvarsområden inom HR-enheten. Detta för att se om dessa olikheter påverkar möjligheten till medarbetarnas balans i vardagen. Skillnaderna vi sökte bland urvalet till intervjuerna visade sig inte ha betydelse för resultatet. Istället var medarbetarnas olika individuella förutsättningar relevanta för att kunna skapa balans.  Det vill säga familjeförhållanden samt vart medarbetarna befinner sig i livet.  Resultatet i analysen visar att flexibilitet och tillgänglighet är två viktiga faktorer när obalans uppstår men också för att skapa balans. Medarbetarna i undersökningen har samma förutsättningar på arbetsplatsen, nämligen de flexibla arbetstiderna. Utifrån möjligheten att planera sina dagar själv kan medarbetarna också använda sina egna tillvägagångssätt för att skapa balans som till exempel träning eller andra intressen. Däremot kan inte ett flexibelt arbete garantera en balans mellan de olika sfärerna. Har medarbetaren svårt att hantera flexibilitet i arbetet är det också svårt för medarbetaren att hantera kraven utifrån. Deltagarna i studien menar att det flexibla arbetet är något de lär sig hantera med åren och som utvecklas till en individuell skicklighet. Det krävs erfarenhet i denna arbetsform för att lära sig planera och prioritera för att få livets olika delar att gå ihop.