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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
301

Representations of 'home' and 'exile' in Breyten Breytenbach's Memory of snow and of dust.

Jansen, Tanya. January 2010 (has links)
This mini-dissertation aims to examine the way in which Breyten Breytenbach explores the concepts of home and exile in his novel Memory of Snow and of Dust. The author captures and conveys the experience of exile, and envisages through the exile’s double vision a more complicated conception of home. Through the novel one is able to observe the exilic condition and gain access to new insights. The narrative structure comprises of various discourses and illustrates the restless nature of an unsettling and unstable existence. In the Introduction the theoretical framework for this study is outlined: recent developments in postcolonial and postmodern theories, Breytenbach’s oeuvre and literary criticism devoted to his work are discussed. Chapter One examines the distressing journey into a new awareness of what constitutes home. Chapter Two inspects the restless, yet regenerative condition of exile. Chapter Three considers a more fluid response to spatiality and the concept of home through an exploration of fresh perspectives that may emerge from extreme mental suffering. This study concludes with an affirmation of the relevance of Memory of Snow and of Dust, in times in which the overlapping boundaries of home and exile are becoming a global condition. / Thesis (M.A.) - University of KwaZulu-Natal, Durban, 2010.
302

Toxicological analysis of house dust collected from selected Durban residental buildings.

Nkala, Bongani Alphouse. January 2009 (has links)
Indoor air quality is described as the chemical, physical and biological characteristics of air in a residential or occupational indoor environment. In residential settings, there are many contributions to indoor pollution levels namely; human activities, biological sources and outdoor air. There has been increased focus on house dust due to its potential to contain biological and chemical pollutants in indoor environments. These have the potential to cause harm to human health. The purpose of this study was to conduct toxicological analysis of house dust collected from inside selected Durban residential buildings. The objectives of this study were to isolate, identify and quantify mould occurrence in house dust samples; to measure the occurrence of heavy metals (arsenic, lead and mercury) in house dust; and to analyse the cytotoxicity of house dust on human lung bronchus carcinoma epithelial line (A549) and human lung bronchus virus transformed epithelial cell line (BBM). One hundred and five house dust samples were obtained from households that participated in the South Durban Health Study. In each home, a sample of settled dust was collected, using standardized protocols, then sieved and individually packed into polystyrene bags. The samples were taken from three surface areas namely; living room couches, bed mattresses, and carpets. Well documented methods were used for the isolation, identification and quantification of mould. The samples for heavy metals analysis were sent to Umgeni Water (chemistry laboratory, Pietermaritzburg) where standardised methods were used. Human cell lines were treated with five different dilutions of each house dust extract. Cell viability was assessed using the MTT assay. Toxic effects of house dust extract were analyzed, following house dust extract treatment and cells were stained with double dye (annexin-V- and propidium iodide) and analysed with flow cytometry, and fluorescent microscope. Cytokines were analysed by Microbionix (Neuried, German) using a Luminex®100 plate reader for multiplex human cytokines analysis. There were (n=128) mould types isolated and (n=105) were identified, of which (n=10) were predominately isolated moulds. This was further confirmed by Allerton Provincial Laboratory in Pietermaritzburg. Among the isolated genera in all three surface areas, Rhizopus spp and Penicillium spp were widely distributed throughout surface areas in greater proportion. The overall highest mean which was reported in this study and expressed in colony forming unit per gram (CFU/g) for Penicillium spp ranged (3400 - 62316 CFU/g) obtained from living room couches, followed by Rhizopus spp (5200 - 15990 CFU/g). The mould results were compared with the South African Occupational Health and Safety Act (OHSA) 85 of 1993 as amended suggested guidelines of 1,000, 000 CFU/g. The findings of this study suggest the moulds in the homes studied were below the suggested guideline. However, this does not imply that the indoor conditions are unsafe or hazardous. Instead, the findings act as an indicator of moulds presence indoors. The type of airborne mould, its concentration and extent of exposure and the health status of the occupants of a building will determine the health effects on an individual. Heavy metals were detected in the dust in the following ascending order: arsenic (As) ranged from 1.3 ug/g -18.4 ug/g (mean, 4.26 ug/g), lead (Pb) ranged from 28.0 - 872 ug/g (mean 171.66 ug/g), and mercury (Hg) ranged from 0.6 -19.0 ug/g (mean, 2.22 ug/g). The mean concentration of lead in the dust was within the range of Canadian National Classification guidelines on residential contamination (500 ug/g). There was numerous numbers of samples in this study that exceeded these guidelines. The mean concentration of arsenic was within residential soil guidelines (20 ug/g). Mercury was within limits when compared with Global Hg project guidelines of soil/residential (6.6 ug/g), thought some of samples were notably above this mean. The ability of house dust extract to lower the cell viability which was slightly above 80% (prior treatment) to less than 50% (post treatment) in both cells was observed in this study. The findings in this study showed that dust extract are toxic to human cell lines, and cells undergone a degree of apoptosis and necrosis 62% (A549) and 99% (BBM). The cytokines serve an important role in the non-specific defence external against insults. It was observed that A549 cells up-regulated the release of IL-6 and IL-8 pro-inflammatory cytokines and under-regulated the release of other cytokines analysed (IL-4, IL-13, and TNF-a). BBM cells released IL-4, IL-8 and IL-13 within limit of detection. The presence of moulds in these sampled indoor household dusts, which is comparable with findings elsewhere indoors, show that moulds act as an indicator for building conditions such as dampness, which supports mould growth. Individuals, whether they are sensitized or not, may develop allergic reactions towards spores, thus the elevated numbers of spores quantified in this study are of concern. Some of the heavy metals reported in this study were higher or marginally higher than international norms and guidelines. The findings in this study strongly suggest that house dust extract is toxic to human lung cell lines. It must be noted, however, that this study may not reflect all that happens when a human lung is exposed to house dust. The findings of this study could contribute to the development of South African indoor air guidelines. In conclusion further study needed to be undertaken with respect to air pollution disease such as allergic; the reason being this study shown the reduced expression of cytokines that are involved in allergic inflammation. / Thesis (M.Med.)-University of KwaZulu-Natal, Durban, 2009.
303

Detection of filamentous fungi in the homes and airways of patients with asthma

Fairs, Abbie January 2012 (has links)
Asthma is a heterogeneous condition characterised by variable airflow obstruction, airway inflammation and hyper-responsiveness. Fungal sensitisation has been associated with asthma severity; and airways colonisation by the pathogenic fungus Aspergillus fumigatus has been associated with a progressive lung function decline in allergic bronchopulmonary aspergillosis. Interest in the home environment as a source of fungal exposure is increasing; however, there are still no accepted guidelines or standardised methods for the quantification of indoor fungal levels. We sought to i) investigate typical airborne fungal spore concentrations in homes and to compare exposure levels in asthma patients grouped according to either A. fumigatus sensitisation or sputum culture; ii) fully characterise the fungal biota capable of colonising the airways in patients with asthma; and iii) define the clinical characteristics of fungal colonisation. Aspergillus/Penicillium-type conidia exhibited indoor predominance and independence of season, and were highest in old, terraced, non-insulated properties. A. fumigatus was the predominant fungus isolated from sputum and IgE sensitisation to A. fumigatus was associated with reduced post-bronchodilator FEV1 in patients with asthma. Sputum culture of filamentous fungi was also associated with reduced lung function, with predominant fungi comprising Aspergillus and Penicillium species; notably Penicillium piceum and species of Aspergillus section Nigri. Higher levels of airborne A. fumigatus were detected in homes of asthmatics with a positive sputum culture for A. fumigatus. In conclusion, sensitisation to A. fumigatus and airways colonisation by fungi are associated with reduced lung function in moderate to severe asthma; and this study provides a direct link between home exposure and airways colonisation.
304

CHARACTERIZING THE VARIABILITY IN RESPIRABLE DUST EXPOSURE USING JOHNSON TRANSFORMATION AND RE-EXAMINING 2010 PROPOSED CHANGES TO THE U.S. UNDERGROUND COAL MINE DUST STANDARD

Khan, Al I. 01 January 2013 (has links)
Coal workers’ pneumoconiosis (CWP), commonly referred to as black lung, is a chronic lung disease that results from the inhalation and deposition of coal dust in the lungs. While this disease continues to afflict coal miners, its prevalence has steadily declined over three decades since 1970. Based on a voluntary X-ray surveillance program, conducted by the National Institute for Occupational Safety and Health (NIOSH), this downward trend, however, ended in 2000 and has actually begun to rise. The Mine Safety and Health Administration (MSHA) instituted a Comprehensive Initiative to “End Black Lung” to combat the reported upturn in black lung disease. Rulemaking, with the intent of strengthening respirable dust regulations, is a major part of this initiative. This thesis addresses a controversial aspect of the newly proposed rules – single-shift compliance sampling. Establishing new requirements for respirable dust compliance requires an understanding of both the accuracy and variability of measurements. Measurement variability is especially important in underground mining where the workplace is constantly moving and ventilation controls are continually changing. The results of a ventilation study performed in three underground coal mines are presented in this thesis. A total of 600 dust-concentration measurements were obtained in this study using Continuous Personal Dust Monitors (CPDMs). The data was analyzed to determine the variability associated with taking dust measurements in the mining workplace. The Johnson transformation was found to produce the best-fit distribution model for the data. This thesis summarizes the results of this study and presents a statistical procedure for establishing an exposure limit.
305

Deriving Dust Properties in Star Forming Clumps: a Look Across the Perseus Molecular Cloud with Herschel and SCUBA-2

Chen, Michael Chun-Yuan 22 April 2015 (has links)
Herschel and JCMT surveys of nearby star-forming regions have provided excellent images of cold dust emission across several wavelengths with unprecedented dynamic range and resolutions. Here we present spectral emissivity index and temperature maps of dust in the star-forming clumps of the Perseus molecular cloud determined from fitting SEDs to the combined Herschel and JCMT observations in the 160 μm, 250 μm, 350 μm, 500 μm, and 850 μm bands, employing the technique developed by Sadavoy et al. (2013). In NGC1333, the most complex and active star-forming clump in Perseus, we demonstrate that CO line contamination in the JCMT SCUBA-2 850 μm band is typically insignificant. The derived spectral emissivity index, β, and dust temperature, T, ranges between 0.8 - 3.0 and 7 - 50 K, respectively. Throughout Perseus, we see indications of heating from B stars and embedded protostars, and smooth β variations on the smaller scales. The distribution of β values seen in each clump differs from one clump to another, and is in general different from the diffuse ISM values (i.e., ~2), suggesting that dust grain evolution is significant in star-forming clumps. We also found coincidences between low β regions and local temperature peaks as well as locations of outflows, which may provide hints to the origins of these low β value grains, and dust grain evolution in star-forming clumps in general. / Graduate / mcychen@uvic.ca
306

Heterogeneous Photochemistry of Atmospheric Dusts and Organic Films

Styler, Sarah Anne 01 September 2014 (has links)
Little is currently known regarding the nature and consequences of interactions between photoactive surfaces, including mineral dust and ‘urban film’, and gas-phase pollutants in urban environments. In order to address this knowledge gap, this thesis explores the photochemical reactivity of these environmental surfaces in controlled laboratory settings. The photoenhanced ozonation of pyrene, a toxic product of incomplete combustion, proceeds at different rates and via different mechanisms at three model ‘urban film’ surfaces. These results are important because they suggest that the reactivity of a molecule on simplified surfaces may not accurately reflect its reactivity in the real environment. The photooxidation of isopropanol at the surface of TiO2, here used as a proxy for the photoactive component of mineral dust, yields gas-phase acetone. This chemistry is amplified by nitrate, a major surficial component of atmospherically processed dust. These results suggest that dust has the potential to convert non-absorbing species to photochemically active species, and thereby serve as a source of reactive organic radicals for further gas- or surface-phase chemistry. Oxalic acid, the most atmospherically abundant dicarboxylic acid, is efficiently oxidized to gas-phase CO2 at the surface of Mauritanian sand and Icelandic volcanic ash. These experiments indicate that the lifetime of oxalic acid may be limited in arid regions by Fe and Ti-catalyzed aerosol-phase photochemistry. Fluorotelomer alcohols (FTOHs), a class of industrial chemicals used in the production of surface coatings, undergo photooxidation at the surface of sand and ash to yield toxic and persistent perfluorinated carboxylic acids (PFCAs). These results provide the first evidence that the metal-catalyzed heterogeneous oxidation of FTOHs may act as a local source of aerosol-phase PFCAs. Illumination of Nigerien sand in the presence of gas-phase SO2 leads to the formation of surface-sorbed sulfate. This chemistry proceeds more efficiently on fine sand than on coarse sand. In chamber experiments, the illumination of SO2 in the presence of realistically produced dust aerosol results in new particle formation. Together, these results suggest that SO2 photochemistry at the dust surface has the potential to change not only dust hygroscopicity but also the net scattering potential of dust-containing air masses.
307

The development of a strategic plan for a company in the dust suppression industry / de Necker A.

De Necker, Adele January 2011 (has links)
The general aim of this study was to develop a strategic plan for a company in the dust suppression industry. Currently there is no formal process documented or analysis done within the company regarding strategic planning due to the company being founded, extensive growth taking place year on year and the urgent need for the operations to be established, in order for the company to start selling their products and services. The study was conducted among a sample of 45 junior, middle and senior management employees within this company. The data collected from the participants were collected personally via interviews and a strategic planning questionnaire and recorded electronically by the Statistical Consultation Services at the North–West University and the data were analysed by means of the Statistical Package for Social Sciences (SPSS V18). In addition to the structured questionnaires, management was also interviewed to assess their views on the strategic planning at the company. The results and findings indicated that there was some strategic planning actions lacking and that formal strategic planning that defines objectives and assessment of the various situations within the company, are not properly performed. The author was however able to evaluate and determine where the company is going over the next three years. The study draws a number of conclusions and makes recommendations with regard to strategic planning, one of which is that the company should follow a more structured and formalised approach. / Thesis (M.B.A.)--North-West University, Potchefstroom Campus, 2012.
308

The development of a strategic plan for a company in the dust suppression industry / de Necker A.

De Necker, Adele January 2011 (has links)
The general aim of this study was to develop a strategic plan for a company in the dust suppression industry. Currently there is no formal process documented or analysis done within the company regarding strategic planning due to the company being founded, extensive growth taking place year on year and the urgent need for the operations to be established, in order for the company to start selling their products and services. The study was conducted among a sample of 45 junior, middle and senior management employees within this company. The data collected from the participants were collected personally via interviews and a strategic planning questionnaire and recorded electronically by the Statistical Consultation Services at the North–West University and the data were analysed by means of the Statistical Package for Social Sciences (SPSS V18). In addition to the structured questionnaires, management was also interviewed to assess their views on the strategic planning at the company. The results and findings indicated that there was some strategic planning actions lacking and that formal strategic planning that defines objectives and assessment of the various situations within the company, are not properly performed. The author was however able to evaluate and determine where the company is going over the next three years. The study draws a number of conclusions and makes recommendations with regard to strategic planning, one of which is that the company should follow a more structured and formalised approach. / Thesis (M.B.A.)--North-West University, Potchefstroom Campus, 2012.
309

Laboratory Studies of Deposition Mode Heterogeneous Ice Nucleation: Effect of Ice Nuclei Composition, Size and Surface Area

Kanji, Zaminhussein Abdulali 18 February 2010 (has links)
The indirect aerosol effect contributes to major uncertainties in determining the radiation budget of the earth. A large uncertainty is due to the formation of ice clouds onto natural or anthropogenic aerosols. Field studies have shown that mineral type particles are often associated with ice crystals in the mid-upper troposphere and given the long residence time in the atmosphere of dust particles (~2 weeks in the absence of precipitation), their contribution to ice formation processes is not fully defined. In order to probe ice formation onto natural mineral dust in a setting where it could be suspended as aerosol, a new continuous flow diffusion chamber (CFDC) was built. This allowed investigations of the effects of total aerosol surface area and particle size. The CFDC was also used in an international inter-comparison of ice nucleation instrumentation to compare efficiencies of soot, biological aerosol (bacteria) and samples of natural desert dusts from different regions of the world. The laboratory observations were parameterized using nucleation rates (Jhet) and contact angles () as described by classical nucleation theory. For both this experimental technique and a static one developed during the candidate’s Masters degree, mineral dust particulate proved to be the most efficient ice nuclei (IN) activating at RH with respect to ice (RHi) as low as 105% at T = 233 K. The efficiency varied with particle size and aerosol surface area (SA). Large particles or higher SA activated at lower RHi than small particles or lower SA. The static chamber was sensitive to the first ice event out of a large SA and therefore gave true onset RHi, which was lower than the onset defined by the CFDC studies, which was not sensitive to a single ice event. In addition the static chamber used a broader size range of particulate matter, including super micron particles while the CFDC particles sizes were restricted to below 0.5 µm. Soot and organic coated dust particles were inefficient IN compared to pure dust. Soot aerosols showed some efficiency at T < 233K where deposition ice formation was apparent. The hygroscopic organics had intermediate ice activity between dusts and alkyl-organics and soot. Bacteria aerosols were active in the deposition mode for T as high as 247 K. Contact angles () computed for ice germs forming onto natural mineral dust were small, 7<  < 29, at 223 K for RH ranging from ice to water saturation. It was concluded that there is no single value for the onset of ice formation in the atmosphere via deposition freezing. The associated contact angles show that there is a distribution of active sites on IN and that not all active sites have the same affinity for initiation of ice formation even within the same aerosol type. This work provides evidence that deposition mode nucleation can be an alternate pathway to homogeneous nucleation when mineral aerosols are present in the troposphere since the high T - low RH conditions required for deposition mode nucleation are more easily encountered in the atmosphere than the low T - high RH required for homogeneous nucleation.
310

Relationship between ferromagnetic particles and airborne chrysotile fibres in the asbestos mines and mills of Quebec

Djamgouz, O. T. January 1982 (has links)
Examination of Chrysotile Asbestos from the Eastern Townships of Quebec using optical and electron microscopic methods has shown that Chrysotile fibres are intimately associated with minute particles of magnetite. / Measurements were made using a fluxgate magnetometer of the remnant magnetic fields of bulk commercial fibres and of airborne total dust and of the respirable fraction of airborne dust collected in Quebec asbestos mines and mills using a Hexhlet horizontal eleutriator. The validity of the Hexhlet horizontal eleutriator for respirable fibre collection in the mill environment was determined. It was observed that the remnant magnetic field intensities of airborne dust in laboratory generated dust clouds, and in the work places were related in a meaningful way to the magnetite content of the dust and to the total mass and respirable mass fractions of airborne dust, and also, to the concentrations of fibre greater than 5 micrometre length (aspect ratio > 3:1) measured using phase contrast microscopy. Calibration curves were developed for each of 9 Quebec mills. Repeat calibrations showed the lines to be reproducible within (+OR-) 10 percent. The accuracy of the method for mass dust determination was dependent on sample size with errors as low as (+OR-) 7.5 percent for samples larger than 3 milligrams, and as large as (+OR-) 40 percent for samples of mass smaller than 0.5 milligrams. The relationships between fibre concentrations and remnant magnetic fields were less reproducible and the lower detection limit was limited by the sensitivity of the fluxgate magnetometer. Although the measured remnant magnetic field varied as the magnetite content varied between different mills and commercial fibre products, magnetite to chrysotile ratio remained constant for a given mill and commercial product. Measurements of the remnant magnetic fields of airborne dusts collected in mill environments can thus provide the possibility of the rapid determination of airborne chrysotile fibre concentrations both in terms of mass and number of fibres per litre of air sampled as well as their iron content. / Measurement of the magnetic content of specimens of autopsied lung tissue from asbestos exposed workers indicated that the residual estimated fibre content measured by electron microscopy was less than estimated using magnetic field measurements. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI

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