MSc, Physiotherapy, Faculty of Health Sciences, University of the Witwatersrand / Background: Jet nebulisers are one of the primary devices used in the nebulisation of ventilated patients. It has been observed that due to cost restraints devices marked as “single use” are inadvertently being used as “single-patient-use” devices. This has both ethical and medico legal implications for the ICU. Ventilator-associated pneumonia (VAP) in limited-resource countries carries a large burden of increased mortality, morbidity and cost. Ineffective or absent nebuliser decontamination in ventilated patients can increase the risk of the development of VAP as well as the risk of antibiotic resistance. Objectives: The aim of this study was to examine the current practice of nebuliser decontamination and the incidence of contamination of nebulisers after use within a ventilator circuit, in ICUs in Johannesburg, South Africa. The secondary objectives of the study were to assess the presence of and adherence to a decontamination protocol in intensive care units (ICU) in Johannesburg and to identify which practices were associated with lower or no bacterial growth. Methods: A cross-sectional study design was used which included an interview with the unit manager and an audit of current nebuliser practice in the ICU. Nebulisers that were identified in the interview were then swabbed and streaked on blood agar plates (BAPs). Blood agar plates were then incubated and assessed for bacterial colonisation, number of colony forming units (CFUs) and number of different species of CFUs that were formed. Results: Single-use jet nebulisers represented 93% of nebulisers used within a ventilator circuit. All of the single-use jet nebulisers were being re-used (n=42). None of the hospitals studied had a nebuliser decontamination protocol. The contamination rate for jet nebulisers that had been re-used within the ventilator circuit was 52%. In the group of nebulisers that had bacterial colonisation, the nebulisers that were stored in a sterile drape had a significantly higher concentration of bacterial growth, than those that were not stored in a sterile drape (p=0.03). Nebulisers are often used in the administration of bronchodilators in ICUs in Johannesburg, South Africa. Colonised nebulisers can create bacterial aerosol when used within a ventilator circuit. A change to single-patient-use devices, such as vibrating mesh nebulisers, may assist in reducing the problem of colonisation of jet nebulisers. Conclusion: The rate of colonisation of jet nebulisers that have been re-used is unacceptably high. ICUs need to develop nebuliser decontamination protocols. Physiotherapists should assist with creating awareness and driving the creation of these protocols. ICUs should be encouraged to change single-use devices to single-patient-use devices. Nebulisers should not be stored in sterile drapes after use in a ventilator circuit.

"Characterizing the effects of subsurface wastewater effluent discharges remains as a significant challenge impacting both ground-water and surface water resources. Important aspects of this challenge relate to the quantification of the main processes affecting oxygen consumption within a wastewater plume and to the ability of representing these conditions over a range of scales. The goal of this research is to improve our understanding of the relevant processes affecting oxygen consumption and thus, controlling natural attenuation in wastewater contaminated aquifers, and also to characterize and quantify these processes through modeling approaches considering different scales. The analysis included consideration of restoration processes associated with a former sewage disposal discharge in Falmouth, MA. The discharge was removed in 1995, and the site has been experiencing natural restoration since removal. A small-scale natural gradient tracer test, completed 6 years after cessation of sewage disposal, was used in previous research to develop parameters to characterize aerobic respiration and nitrification processes, key oxygen consuming processes for this site. In addition, field monitoring by the United States Geological Survey has provided a series of concentration profiles at different locations along the flowpath associated with the contaminant source. For this research, predictions obtained with the existing model were used in conjunction with these concentration profiles to assess the sensitivity and applicability in the parameters from this small-scale test, as well as their pertinence to the larger scale restoration process. By evaluating the applicability of this model to different scales and the associated variability of key model parameters, the approach provided an improved characterization of the primary processes affecting oxygen consumption."

This dissertation combines field data, laboratory experiments, and mathematic models to (1) predict the probability of groundwater arsenic (As) contamination caused by geogenic sources and processes in shallow aquifers of the Mississippi Delta in southern Louisiana, (2) study the role microbes play in controlling As mobilization from sediments to groundwaters, and (3) simulate As mobilization and transport caused by changing redox conditions and groundwater geochemistry along a flow path within the southeastern Chicot aquifer in southern Louisiana. A model based on surface hydrology, soil properties, geology, and sedimentary deposition environments predicts that the Holocene shallow aquifers in southern Louisiana are at high risk of As contamination. Sediment incubation and pore-water chemistry suggest that microbes play a key role in mobilizing As from sediments by reductive dissolution of As-bearing Fe(III) oxides/oxyhydroxides. Finally, groundwater samples were collected along a 10 km flow path in the southeastern Chicot aquifer to determine groundwater geochemical parameters and to simulate reactive transport of Fe and As species along the studied flow path. The model well captures the general trends of Fe(II) and As(III) concentrations along the studied flow path and the close correspondence between Fe(II) and As(III) of the both measured and model predicted As(III) and Fe(II) concentrations support the hypothesis that microbially mediated reductive dissolution of As-bearing Fe(III) oxides/oxyhydroxides is the primary mechanism causing As mobilization from sediments to the shallow reducing groundwaters of the Mississippi Delta in southern Louisiana. / 1 / NINGFANG YANG

Because Mexican foods have been implicated in a number of outbreaks of foodborne illness in the United States, production procedures used in Mexican restaurants were investigated by interviewing four managers. Two major problems identified through these interviews were failure to cool large quantities of beans rapidly and failure to reheat beans thoroughly before placement on the steam table. Experiments were designed to study the effects of varying temperatures, duration of incubation, and the location in the product as it might affect aeration on growth of B. cereus and C. perfringens, singly and combined, in cooked mashed pinto beans. Growth of both B. cereus and C. perfringens was rapid at 37°C, with numbers of cells associated with illness reached in 4 and 6 hours, respectively. B. cereus may present more of a health hazard, since obvious signs of spoilage did not occur in these beans until 12 hours, whereas C. perfringens caused obvious spoilage of beans within 6 to 8 hours. At 23°C with B. cereus, the numbers associated with illness were found at 12 hours. However, the beans appeared to be spoiled before this level was reached with C. perfringens at 24 hours. Aeration, as indicated by location in the jar, appeared to have more of an effect on B. cereus growth than on C. perfringens, but good growth of the two species occurred in both top and bottom locations. Restaurant samples of bean dip and mashed beans were analyzed for contamination with B. cereus and C. perfringens. Total aerobic and anaerobic counts were determined. Only two of the 42 samples were found to contain B. cereus or C. perfringens and these were present in low numbers. The total aerobic and anaerobic counts varied from less than 100 to 100,000,000 per gram: chiefly lactic acid bacteria which appeared to be related to the seasoning ingredients. However, one batch of bean dip and one of mashed beans were found to contain large numbers of coagulase-positive S. aureus (>100,000/g). / Graduation date: 1982

Thesis (M.A.) - Simon Fraser University, 2005. / Theses (Dept. of Archaeology) / Simon Fraser University. Also issued in digital format and available on the World Wide Web.

Reproduction de : Thèse d'exercice : Pharmacie : Nantes : 2008. / Bibliogr.

Thesis (M.S.) in Food Science and Human Nutrition--University of Maine, 2009. / Includes vita. Includes bibliographical references (leaves 146-178).

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Biogeochemical reactions and vadose zone transport, in particular gas phasetransport, are inherently coupled processes. To explore feedback mechanisms between these processes in a quantitative manner, multicomponent gas diffusion and advection are implemented into an existing reactive transport model that includes a full suite of geochemical reactions. Multicomponent gas diffusion is described based on the Dusty Gas Model, which provides the most generally applicable description for gas diffusion.Gas advection is described by Darcy's Law, which in the current formulation, is directly substituted into the transport equations. The model is used to investigate the interactions between geochemical reactions and transport processes with an emphasis to quantify reaction-induced gas migration in the vadose zone. Simulations of pyrite oxidation in mine tailings, gas attenuation in partially saturated landfill soil covers, and methane production and oxidation in aquifers contaminated by organic compounds demonstrate how biogeochemical reactions drive diffusive and advective transport of reactive and non-reactive gases. Pyrite oxidation in mine tailings causes a pressure reduction in the reaction zone and drives advective gas flow into the sediment column, enhancing the oxidation process. Release of carbondioxide by carbonate mineral dissolution partly offsets pressure reduction, and illustrates the role of water-rock interaction on gas transport. Microbially mediated methane oxidation in landfill covers reduces the existing upward pressure gradient, there by decreasing the contribution of advective methane emissions to the atmosphere and enhancing the net flux of atmospheric oxygen into the soil column. At an oil spill site, both generation of CH⁴ in the methanogenic zone and oxidation of CH⁴ in the methanotrophic zone contribute to drive advective and diffusive fluxes. The model confirmed that non-reactive gases tend to accumulate in zones of gas consumption and become depleted in zones of gas production. In most cases, the model was able to quantify existing conceptual models, but also proved useful to identify data gaps, sensitivity, and inconsistencies in conceptual models. The formulation of the model is general and can be applied to other vadose zone systems in which reaction-induced gas transport is of importance.