Sliding failures of landfill cover systems are common, and the slip surface is often at the interface between a geosynthetic drainage layer and an underlying textured geomembrane. In an effort to understand the sliding failures, the objectives of this research project are to summarize current regulation and practice in landfill cover design, use experimental methods to characterize the behavior of geosynthetic landfill materials in cover systems approaching failure, and develop models to evaluate the hydraulic performance and stability of landfill cover systems. Inclined plane tests were conducted to explore the behavior of a geosynthetic drainage material/textured geomembrane interface. The interface had effective normal stress dependent strain softening behavior, with more strain softening measured at higher effective normal stresses. A numerical model for confined flow in a drainage layer with a constrained outlet was developed. The model was used to evaluate how water fills and empties from a geosynthetic drainage layer for a variety of inflow conditions and constraints to flow at the outlet. The model was used to demonstrate that a drainage layer that effectively conveys water out of a cover system with a free flowing drainage outlet quickly fills with water when the outlet has a modest constraint to flow. An iterative, numerical model was developed to calculate stability solutions for landfill cover slopes that satisfy force equilibrium and strain compatibility while accounting for effective normal stress dependent strain softening and various pore water pressure conditions. Stability solutions reveal that depending on the water pressure in the drainage layer, the geosynthetic drainage material may experience tension at many points along the slope. It is crucial for the stability of the landfill cover system to maintain free-flowing conditions at the drainage layer outlet. A modest constraint to flow at the outlet has a significant adverse effect on the ability of the landfill cover drainage layer to convey water out of the system, which can lead to instability. The drainage layer outlet should be designed to ensure free flow of water out of the drainage layer. / text

Since the development of knockout and transgenic mouse models, mice have become the most widely used mammalian animal model to study bone. Despite the advances in knowledge of bone biology and function that have occurred from use of mouse models, many studies use primarily qualitative techniques, which may result in overlooking important subtle pathophysiologic changes. The hypothesis of this dissertation is that quantitative techniques to measure bone structure and function could identify the physiologic role of carbonic anhydrase II and calbindin-D28k in mouse bone, despite earlier qualitative studies indicating mice without these proteins have normal bone structure and function. Furthermore, a method to quantify bone function in vivo will be tested in a mouse model.Although carbonic anhydrase II deficient mice are less severely affected than patients, the mice demonstrate features of osteopetrosis including metaphyseal widening and a 50% increase in trabecular bone volume. The mice partially compensate for inhibited osteoclast function by increasing osteoclast number.Calbindin-D28k knockout mice demonstrated an increase in bone volume that results from additional bone at the endosteal surfaces. The higher bone volume results in increased stiffness and failure loads, highlighting the potential use of drugs that inhibit calbindin-D28k to treat diseases such as osteoporosis.Finally, calcium phosphate ceramic and hydroxyapatite particles used as strain gauge coatings demonstrated bone bonding to mouse femora after two months in vivo. The use of hydroxyapatite particles to coat strain gauges is the first time this method has been used with all commercially available materials, and will allow other research groups to use this technique. The major limitation to in vivo bone strain measurement in mice is the relatively large size of the sensors, which resulted in increased second moments of inertia in the implanted bones.Overall, this dissertation demonstrates that the use of quantitative techniques, including histology, histomorphometry, µCT imaging, and mechanical testing can measure subtle changes in bone properties that have been previously overlooked. Development of additional quantitative methods to study bone biomechanics in mouse models may encourage other research groups to quantify bone properties if no changes are noted using primarily qualitative methods.

Clostridium perfringens is an important pathogen in veterinary and medical fields. Understanding epidemiology of C. perfringens diseases and evolution of virulence within C. perfringens necessitates an efficient, time and cost effective strain typing method. Multiple-locus variable-number tandem repeat analysis (MLVA) has been applied to typing of other pathogens and we describe here the development of a MLVA scheme for C. perfringens. We characterized five VNTR loci, and screened 112 C. perfringens isolates to evaluate typability, reproducibility, and discriminatory power of the scheme. All isolates were assigned a MLVA genotype and the technique has excellent reproducibility, with a numerical index of discrimination of 0.995. Thus, MLVA is an efficient tool for C. perfringens strain typing, and being PCR based makes it rapid, easy, and cost effective. In addition, it can be employed in epidemiological, ecological, and evolutionary investigations of the organism.Virulence of this species is not fully understood and it does seem that distribution of the toxin/enzyme genes is erratic within the population. We used the MLVA scheme to investigate evolution of virulence and population structure of this species. Analysis of the phylogenetic signal indicates that acquisition of the major toxin genes and other plasmid-borne toxin genes is a recent evolutionary event, and their maintenance is essentially a function of the selective advantage they confer to strains carrying them in certain micro-niches under different conditions. In addition, it indicates the ability of virulent strains to cause disease in different hosts. More interestingly, there is evidence that certain normal flora strains are virulent when they gain access to a different host species. Analysis of the population structure indicates that recombination events are the major tool that shapes the population and this panmixia is interrupted with frequent clonal expansion that mostly corresponds to disease processes. Signature of positive selection was detected in the alpha toxin gene, suggesting the possibility of adaptive alleles on the other chromosomally-encoded determinants. Finally, C. perfringens proved to have a dynamic population, and availability of more genome sequences, use of comparative proteomics and of animal models would provide more insight into the pathogenicity of this organism.

The project has been done in cooperation with Schenker Åkeri AB in Sweden, Halmstad. The project is based on an inspection made by Arbetsmiljöverket, where they found minor shortcomings with distribution of goods for the employees. The project is an investigation of the drivers’ working environment. Schenker Logistics is one of the world's leading providers of integrated logistics services. Schenker Åkeri AB is a subsidiary to Schenker Logistics and transports 2.4 million tons of goods yearly. The project started with a background study to evaluate drivers working environment. We have studied goods receptions, the working environment, strain injury and injury mechanisms. Methods used was observations, tests, questionnaire surveys and ergonomic and biomechanical calculations. One result of the study is a working model, which gives recommendations for the maximum weight a driver should push and pull. A truck evaluation was done to exam the need for new technical equipment. An ergonomic investigation was done to investigate the drivers’ working tasks. A questionnaire was given to the drivers to evaluate their working environment and tasks. The questionnaire involved questions about stress, handling of goods and technical equipment. Together with Schenker Åkeri AB in Halmstad, an action plan was made. This action plan will be handed over to Arbetsmiljöverket by Schenker.

The Strain Index (SI) has repeatedly shown high levels of validity for differentiating between safe and hazardous tasks for the distal upper extremity (DUE). One limitation of the SI is the lack of reliability data. This study was designed to evaluate the test-retest repeatability of the SI. Fifteen raters, divided into five teams of three, were asked to use the SI to analyze 73 video AVI files of different job tasks; initially as individuals and then as teams. Several months later, raters were asked to repeat individual and team job task assessments. Raters were instructed to analyze tasks using five of six SI task variables, while the sixth was held constant. For three of these task variables, additional data was collected such as peak force and duration of job cycle. Test-retest repeatability was measured using Pearson's R, Spearman's rho, and tetrachoric correlation according to the nature of the variable. Spearman's rho values for individual and team task variable ratings ranged from 0.68 to 0.96 (0.88 average). Pearson's R for task variable data ranged from 0.76 to 0.99 for both teams and individuals with an average of 0.91. The Strain Index's rho values for individuals and teams were 0.70 and 0.84, respectively. For hazard classification, the tetrachoric correlation for individuals was 0.81 and 0.88 for teams. Results of this study support the conclusion that the Strain Index is repeatable when used by teams as well as individuals.

No description available.

The foundation of the education of our country lies in the hands of the primary school teachers. Unfortunately, teachers have to juggle many roles - not only are they expected to teach diverse classes and be a role model, but they also have to deal with social problems - all for very little remuneration. Our teachers are becoming less motivated, frustrated and very despondent and as a result, an increasing number of teachers are suffering from burnout. The objective of this research was to investigate the job characteristics associated with burnout as well as the burnout-strain relationship among primary school teachers in the North-West Province. A stratified random sample of 646 primary school teachers in the North West Province was taken. The Maslach Burnout Inventory - General Survey (MBEGS), Job Characteristics Scale and Your Health Questionnaire (third questionnaire of the ASSET) were used as measuring instruments. Cronbach alpha coefficients, inter-item correlation coefficients, Pearsonproduct correlation coefficients and canonical correlation coefficients were used to analyse the data. Structural equation modelling (SEM) methods were used to construct job characteristic models of burnout. The results showed that overload leads to exhaustion, which leads to cynicism and in turn to lack of professional efficacy. Job resources was found to be related to all three dimensions of burnout, while rewards played a moderating effect between both overload and exhaustion, and job resources and burnout. Exhaustion and lack of professional efficacy lead to physical and psychological strain. Recommendations were made for further research. / Thesis (M.Com. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2004.

An extensive amount of research has been reported in previous literature on the behaviour of FRP-confined concrete subjected to concentric axial compression. However, data on the behaviour of high strength concrete confined with various types and configurations of FRP systems is still lacking and no consensus exists on the complete response of FRP-confined concrete. In addition, no appropriate design guidelines are currently available. This thesis reports results from an experimental program involving 112 cylindrical concrete specimens, 88 of which were FRP-wrapped and the remaining 24 were control specimens. All the specimens were 152 mm in diameter and 305 mm in length. Test variables included: amount of FRP materials used, strength and stiffness of FRP materials, concrete strength, and the health of concrete at the time of strengthening. Experimental results indicated that a pre-repair load of up to 77% of the unconfined concrete strength had no appreciable effect on the stress-strain response of FRP-confined concrete. With an increase of the unconfined concrete strength, the strength enhancement, energy absorption capacity, ductility factor and work (energy) index at rupture of FRP jackets all decreased remarkably. A positive correlation was found between confined concrete ductility and FRP rupture strain. In addition, a gradual post-peak failure of the specimens, observed previously from FRP-confined concrete columns tested at the University of Toronto, was also observed in some of the current tests -- owing to the high speed data acquisition system. That ductile failure can be attributed to the gradual unzipping failure of FRP jacket, which in turn is related to specimen size. A new constitutive model was developed based on material properties, force equilibrium and strain compatibility. The size effect was taken into account in the model, which is able to accommodate concrete with a wide range of strength (25 MPa to 110 MPa) confined with various types and configurations FRP systems. Design equations from CSA S806-02 and CSA S6-06 provide reasonable and conservative estimates for the FRP-confined concrete strength. To calculate the peak strain for FRP-confined concrete, an equation based on the work by Berthet et al. (2006) is proposed.

An extensive amount of research has been reported in previous literature on the behaviour of FRP-confined concrete subjected to concentric axial compression. However, data on the behaviour of high strength concrete confined with various types and configurations of FRP systems is still lacking and no consensus exists on the complete response of FRP-confined concrete. In addition, no appropriate design guidelines are currently available. This thesis reports results from an experimental program involving 112 cylindrical concrete specimens, 88 of which were FRP-wrapped and the remaining 24 were control specimens. All the specimens were 152 mm in diameter and 305 mm in length. Test variables included: amount of FRP materials used, strength and stiffness of FRP materials, concrete strength, and the health of concrete at the time of strengthening. Experimental results indicated that a pre-repair load of up to 77% of the unconfined concrete strength had no appreciable effect on the stress-strain response of FRP-confined concrete. With an increase of the unconfined concrete strength, the strength enhancement, energy absorption capacity, ductility factor and work (energy) index at rupture of FRP jackets all decreased remarkably. A positive correlation was found between confined concrete ductility and FRP rupture strain. In addition, a gradual post-peak failure of the specimens, observed previously from FRP-confined concrete columns tested at the University of Toronto, was also observed in some of the current tests -- owing to the high speed data acquisition system. That ductile failure can be attributed to the gradual unzipping failure of FRP jacket, which in turn is related to specimen size. A new constitutive model was developed based on material properties, force equilibrium and strain compatibility. The size effect was taken into account in the model, which is able to accommodate concrete with a wide range of strength (25 MPa to 110 MPa) confined with various types and configurations FRP systems. Design equations from CSA S806-02 and CSA S6-06 provide reasonable and conservative estimates for the FRP-confined concrete strength. To calculate the peak strain for FRP-confined concrete, an equation based on the work by Berthet et al. (2006) is proposed.

The inherent nature of distributed acoustic sensing technology is a direct result of two key components: optical fiber and the speed of light. Because the speed of light is constant and optical fiber is an isolated medium, combining the two creates a mechanism insulated from environmental interference that effectively “moves” at the speed of light. This process is most visible in the telecommunications industry where the technology transports large amounts of data over significant distances at very high speeds. The same factors that make optical fiber excellent for transporting data (high speed and low environmental interference) also make the technology very applicable for precise measuring applications. Because optical fiber is insulated, a change to the fiber will have a pronounced (measurable) effect. These measurable effects manifest themselves as changes in the amount of light that is reflected within the optical fiber. This change in reflected light can be measured and quantified to indicate both the specific location along the fiber where the change in reflection occurred and the magnitude of the change in reflection. Knowing both the location of the affected area and the extent to which the reflection changed allows for precise measuring and subsequently, educated inferences about what caused the changes initially. The ability of optical fiber to detect changes at myriad intervals over long distances has particular appeal for functions involving remote and hard to get to environments. Both of these conditions are inherent to the petroleum industry and provide substantial incentive for investigating DAS for oilfield applications.