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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.
471

Chemistry and speciation of potentially toxic and radioactive elements during mine water treatment

Madzivire, Godfrey January 2012 (has links)
Philosophiae Doctor - PhD / Mine water poses a serious environmental challenge and contains elements such as Fe, Al, and Mn in potentially toxic concentrations. The major anion in mine water is sulphate. The complexity and diversity of mine water composition makes its treatment very expensive, and there is no “one-fits-all” treatment option available for mine water. Active treatment of mine water produces water with good quality but the processes are not sustainable because of the costs. Previous studies have shown that acid mine drainage can be treated with coal FA to produce better quality water. The use of coal FA, a waste material from coal fired power station and mine water would go a long way in achievement of sustainable treatment of mine water as per previous studies. In this study mine water and coal FA were characterized to determine their physiochemical properties. This study linked the modelling results obtained by using the Geochemist’s workbench (GWB) software to the results obtained during the actual treatment of Matla mine water and Rand Uranium mine water using coal FA and lime. The chemistry involved when Matla mine water and Rand Uranium mine water were treated with flocculants was also investigated. Lastly the chemistry and kinetics involved was investigated when mine water was treated with various ameliorants such as Matla coal FA, lime and/or Al(OH)3 using jet loop mixing or overhead stirring. Mine water from Matla coal mine had a pH of 8 and therefore was classified as neutral mine drainage (NMD). Rand Uranium mine water had a pH of less than 3 and therefore was classified as acid mine drainage (AMD). The concentration of sulphate, Na, Ca, Mg, B, Hg, Se and Cd ions in Matla mine water was 1475, 956, 70, 40, 15, 2.43, 1.12 and 0.005 mg/L respectively. The concentration of sulphate, Fe, Ca, Mn, Mg, Al, B, Cr, Pb, U, Cd, Se and As ions in Rand Uranium mine water was 4126, 896, 376, 282, 155, 27, 5.43, 3.15, 0.51, 0.29, 0.007, 0.06 and 0.006 mg/L respectively . These concentrations were above the target water quality range (TWQR) for potable water set by the Department of Water Affairs (DWA) and World Health Organization (WHO). The gross alpha radioactivity was 6.01 Bq/L and gross beta radioactivity was 6.05 Bq/L in Rand Uranium mine water.
472

Petrophysical evaluation of sandstone reservoirs of the Central Bredasdorp Basin, Block 9, offshore South Africa

Parker, Irfaan January 2014 (has links)
>Magister Scientiae - MSc / This contribution engages in the evaluation of offshore sandstone reservoirs of the Central Bredasdorp basin, Block 9, South Africa using primarily petrophysical procedures. Four wells were selected for the basis of this study (F-AH1, F-AH2, F-AH4, and F-AR2) and were drilled in two known gas fields namely F-AH and F-AR. The primary objective of this thesis was to evaluate the potential of identified Cretaceous sandstone reservoirs through the use and comparison of conventional core, special core analysis, wire-line log and production data. A total of 30 sandstone reservoirs were identified using primarily gamma-ray log baselines coupled with neutron-density crossovers. Eleven lithofacies were recognised from core samples. The pore reduction factor was calculated, and corrected for overburden conditions. Observing core porosity distribution for all wells, well F-AH4 displayed the highest recorded porosity, whereas well F-AH1 measured the lowest recorded porosity. Low porosity values have been attributed to mud and silt lamination influence as well as calcite overgrowths. The core permeability distribution over all the studied wells ranged between 0.001 mD and 2767 mD. Oil, water, and gas, were recorded within cored sections of the wells. Average oil saturations of 3 %, 1.1 %, and 0.2 % were discovered in wells F-AH1, F-AH2, and F-AH4. Wells F-AH1 to F-AR2 each had average gas saturations of 61 %, 57 %, 27 %, and 56 % respectively; average core water saturations of 36 %, 42 %, 27 %, and 44 % were recorded per well.
473

Social anxiety and threat perception : An event-related potential study

Sutradhar, Adithi January 2020 (has links)
The late positive potential (LPP) is an event-related potential (ERP) component associated with increased affective processing which seems to strongly respond to threats and to be sensitive to emotional faces. Some studies indicate that the LPP is modulated by anxiety symptoms, while others fail to find support for these observations. The facial width-to-height ratio (FWHR) is a facial-masculinity metric that refers to cheekbone width, divided by upper facial height (top of the lip to between the brows). Consequently, FWHR has by some researchers been proposed to serve as a cue of threat. For example, high FWHR and diverse emotional faces (e.g., angry faces) are perceived as more threatening than low FWHR faces. Individuals with social anxiety are thought to be biased towards the threat. The literature has indicated that high FWHR faces in combination with angry facial expression can elicit larger LPPs compared to low FWHR and neutral faces. The current experiment investigated subjective ratings in addition to the LPP in response to high and low FWHR faces in combination with an angry and neutral expression, to examine how different facial morphology and affective cues influence the perception of threat to individuals with high social anxiety. This data, in combination, suggests that high FWHR is a salient threat-related social stimulus that might have a firm influence on the perception of other peoples’ faces. Initial results do not support a significant relationship between increased LPP modulation in individuals with high social anxiety compared to individuals with low social anxiety. However, it opens up for discussion regarding how social anxiety should be approached in future LPP research.
474

Vi finns bara där och lever men på riktigt är vi onödiga : En studie om elevers möjligheter att reflektera över livsfrågor i svenskämnets litteraturundervisning

Larsson, Jenny January 2020 (has links)
Undersökningen består av en fallstudie av ett tematiskt arbete med den dystopiska genren på en högstadieskola i åk 8 och 9 samt en kvalitativ innehållsanalys av elevtexter som producerades under arbetsområdet. Resultatet analyserades med utgångspunkt i de teoretiska perspektiven receptionsteori och främmandegöring. Resultatet visar att eleverna reflekterade över livfrågor som rörde tematiken i de texter som de mötte. De dystopiska verken gav flera möjligheter för eleverna att reflektera över livsfrågor som till stor del handlade om faror med teknikutvecklingen men också vad som gör livet meningsfullt och människan lycklig. Det som både gav möjligheter men också begränsade elevernas möjlighet att reflektera över texterna var att lärarna styrde vad eleverna skulle reflektera över. Lärarnas stöd och frågor var dock avhängigt för elevernas förmåga att kunna ta till sig och förstå texterna. När eleverna lämnades mer ensamma med sina frågor och tolkningar var det svårare för dem att uttrycka varför de tyckte som de tyckte eller kände som de kände.
475

Jämställdhetsintegrering som institutionaliserad strategi : En studie om jämställdhetsintegreringens institutionalisering och transformativa potential i två svenska kommuner

Hermansson, Elin January 2020 (has links)
Gender mainstreaming is the main strategy for achieving gender equality in Sweden. With gender mainstreaming, a gender equality perspective is to be included in all areas, at all levels and all parts of the policy process. The strategy is considered to have a transformative potential, and the ability to reveal and challenge the genderedness of institutions. However, it has been criticized for being technocratic and not leading to the intended transformative effects. In this thesis, the institutionalization of gender mainstreaming is examined using a qualitative method based on most-likely cases: two Swedish municipalities. The aim of the thesis is twofold – to examine the strategy’s level of institutionalization, and to examine in what way it has been institutionalized in relation to the transformative potential. The study draws on institutionalization theory and theories related to gender mainstreaming’s transformative potential. Interviews with politicians and public officials constitute the main material, and are supplemented with official documents. The findings suggest a medium level of institutionalization, with a slightly higher level in one of the municipalities due to more evolved mechanisms for support and quality assurance. The institutionalization appears to be more transformative than perhaps anticipated based on previous research – it is to a greater extent transformative than technocratic.
476

Computational and experimental studies of graphene and carbon nanotubes

Shai, Moshibudi January 2016 (has links)
Thesis (M. Sc. (Physics)) -- University of Limpopo, 2016. / Bilayer graphene and single-walled carbon nanotubes were studied through classical molecular dynamics using Tersoff potential. The Tersoff potential has been the most successful model to replicate much of the semiconducting properties in carbon structures. The simulations were performed within a canonical (NVT) ensemble for structural properties and isothermal–isobaric ensemble (NPT) for thermodynamic properties of both materials. The bilayer graphene consists of two models of 64 and 256 atoms. Single-walled carbon nanotubes consist of three chiral structures of 264 atoms which is cnt(12,10), 260 atoms which is cnt(10,12) and armchair structure of 312 atoms which is cnt(12,12). The structural and thermodynamics properties were investigated in a range of temperature from 300 - 5000 K. It has been found that some of the properties of the graphene and carbon nanotube are similar. Graphene256 was found to be more stable than graphene64 and the armchair cnt(12,12) appears to be more mechanically stable than chiral cnt(12,10). Graphene and single-walled carbon nanotubes were also studied using X-ray diffraction and atomic force microscopy (AFM). The lattice constant for both materials were calculated and they agree well with the computational results. For carbon nanotubes, different solvents were used for characterization using the AFM. Chloroform was the best solvent since we managed to find some bundles of carbon nanotube. For ethanol and toluene solvents we did not managed to get any bundles. The diameter of single-walled carbon nanotube was determined only on a solution that chloroform solvent was used.
477

The Teratogenic Potential of Atrazine and 2,4-D Using FETAX

Morgan, M., Scheuerman, Phillip R., Bishop, C., Pyles, Rebecca A. 01 January 1994 (has links)
No description available.
478

Understanding the characteristics of droughts over Eastern Africa in past and future climates

Nguvava, Mariam Melikizedek 17 February 2021 (has links)
Drought poses a threat to socio-economic activities across eastern Africa and its river basins. While there are indications that global warming may continue to enhance evaporation and intensify droughts at all scales, most drought projections over eastern Africa are based on rainfall alone and are limited to meteorological droughts. The present study combines rainfall and Potential Evapotranspiration (PET) to examine the characteristics of meteorological and hydrological droughts in present and future climates at the regional and river basin scales. To accomplish that we have applied five objectives; i) Study the temporal and spatial characteristics of eastern Africa droughts modes, ii) Investigate how some atmospheric teleconnections influence the characteristics of the Africa droughts modes, iii) Examine the influence of 1.5°C and 2°C global warming levels on drought modes in eastern Africa under two future climate scenarios, RCP 4.5 and RCP8.5 iv) Assess how increases in global warming will influence drought characteristics over eastern African river basins. v) Examine the potential impacts of climate change and land use change on water availability in the Rufiji River basin (RRB), Tanzania, with an emphasis of hydrological droughts in this basin. Different types of datasets, including gridded and station observation datasets, regional climate model simulations (CORDEX: Coordinated Regional Climate Downscaling Experiment) and hydrological simulations (SWAT: Soil and Water Assessment Tool), were analysed for the study. The meteorological drought were characterised using two indices (i.e. Standardized Precipitation Evapotranspiration Index, SPEI; Standardized Precipitation Index, SPI) at 3- and 12-month scales, while the hydrological droughts were characterised using four indices (i.e. soil water index, SWI; Surface Runoff Index, RFI; Water Yield Index, WYI; and Stream Flow index, SFI). The study combined principal component analysis (PCA) with wavelet analysis to identify the spatio-temporal structure of four dominant drought modes over the region. It also used wavelet coherence to quantify the influence of four atmospheric teleconnections (i.e. El Niño Southern Oscillation, ENSO; Indian Ocean Dipole, IOD; Tropical Atlantic Dipole Index, TADI; and Quasi-Biennial Oscillation, QBO) on the drought modes. The study also projects the characteristics of future droughts over eastern Africa and its major river basins at different global warming levels (GWLs). Series of hydrological simulations were used to assess the sensitivity of future droughts to four land use change scenarios (i.e. increase in forestry, shrubs, cropland and agriculture) over the Rufiji River Basin (RRB), a prominent river basin in eastern Africa. Although eastern Africa have been documented with several drought studies, the application of a combination of PCA, Wavelet analysis, wavelet coherence and Self Organizing Maps provides more comprehensive representation of droughts in the region using SPEI/SPI derived from both models and observations The results of the study show that the four drought modes, which have their core areas over different parts of eastern Africa, account for more than 45% of drought variability in the region. All the drought modes are strongly coupled with either ENSO or IOD indices (or both); but, in addition, one of the modes is also strongly coupled with the TADI. CORDEX models give a realistic simulation of the relevant climate variables for calculating drought indices over eastern Africa and the river basins. However, the ensemble mean struggles to reproduce the spatial distribution and frequency of drought intensity in the region. The CORDEX simulations project no changes in the spatial structure of the drought modes but suggest an increase in SPEI drought intensity and frequency over the hotspots of the drought modes and elsewhere in the region. The magnitude of the increase, which varies over the drought mode hotspots, increases with increasing GWLs. The projections also show that the increase in intensity and frequency of drought can be attributed more to increased PET than to reduced precipitation. In contrast to the SPEI projection, the SPI projection shows a weak change in intensity and frequency of droughts, and the magnitude of the increase does not vary with the GWLs. Over the river basins, the SPEI projections are more robust than the SPI projections. Over the RRB, the future projections of some hydrological drought indices (i.e. RFI and SFI) follow the change in the SPEI projections, while others (i.e. SWI and WYI) follow that of SPI. Among the four land use scenarios considered, only forestry and shrubs show a substantial change in the hydrological drought indices. The results of the study thus give valuable insight into the characteristics of future droughts in eastern Africa and provide a useful guide to the effectiveness of using land cover to reduce the severity of hydrological droughts over river basins in the region. However, resolution of CORDEX dataset (50km, i.e. 0.44deg) could be among the potential limitation as it is too low to capture the influence of local-scale processes (e.g. sea breeze, mountain induced circulations) on drought over the region.
479

An investigation on the experiences, causes and consequences of unemployment amongst Graduate Youths in Ga-Kgapane, Limpopo Province of South Africa

January 2020 (has links)
Magister Artium (Development Studies) - MA(DVS) / All around the world, graduate youths are experiencing increasing high number of unemployment, compared to older people of the labour force. This rising rate of unemployment amongst graduate youths has been noticed since the global financial crisis. In South Africa, youth unemployment is on the rise, which leads to social, economic and political challenges. Graduate youth unemployment is crippling the economy of South Africa. Therefore, this study was undertaken to investigate the experiences, causes and consequences of unemployment amongst graduate youth in Ga-Kgapane Limpopo province of South Africa, with an objective to provide concrete recommendations on the ways in which the public and private sectors can tackle challenges of graduate youth unemployment. In the study, a qualitative approach was used to collect data and to analyse data. 13 participants who met the criteria was selected using purposive sampling.
480

Theoretical investigation of protein functions related to electron and ion transports working in thermal fluctuation / イオンと電子が関わる生体分子機能におけるタンパク質熱ゆらぎの役割の理論的解明

Cheng, Cheng 25 March 2019 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21593号 / 理博第4500号 / 新制||理||1646(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 林 重彦, 教授 谷村 吉隆, 教授 寺嶋 正秀 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

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