Equine protozoal myeloencephalitis (EPM), predominantly caused by the protozoa Saracocystis neurona, is a common neurologic disease in horses from North America. Equine exposure to the parasite occurs frequently as the protozoa is excreted in opossum (Didelphis virginiana) feces and contaminates the horse's environment. However, clinical neurologic disease only emerges in a small fraction of exposed horses. The seemingly protective immune response that develops in some exposed horses but not all is not fully defined. Previous reports utilizing horse EPM models and immune compromised mouse models, which develop disease simulating EPM after infection with S. neurona, have reported a role of T-lymphocytes and the cytokine interferon gamma, in disease protection. As part of this dissertation, the role of T-lymphocytes and IFNγ was further elucidated. It was determined that IFNγ production is essential for T-lymphocytes to offer protection against S. neurona induced encephalitis, in immune compromised mice. Another factor hindering prognosis of EPM affected horses is treatment failure. The efficacy of the antiprotozoal decoquinate, was tested and found to be ineffective at preventing S. neurona encephalitis, in immune compromised mice. However, the antiprotozoal, diclazuril, was found to be effective at preventing S. neurona encephalitis in immunocompromised mice but once treatment was terminated, infection persisted, and neurologic disease developed. In-situ methods were employed to extensively evaluate the immunopathology of spinal cord tissue samples collected from EPM affected horses. A novel in-situ hybridization technique was successfully utilized to identify S. neurona in tissue samples collected from horses with EPM. This technique will create new opportunities for investigating the immunopathology of EPM. Overall results from the studies conducted in this dissertation suggest that IFNγ production from T lymphocytes is essential for them to offer protection against S. neurona encephalitis. Additionally, further insight on FDA approved and non-FDA approved treatment options for S. neurona infection was gained through the use of the B6Ifnγ -/- mouse model. Collectively, these studies expanded on the knowledge of an understudied equine neurologic disease. / Doctor of Philosophy / Horses are susceptible to the neurologic disease Equine Protozoal Myeloencephalitis, more commonly referred to as EPM by equine enthusiasts. The disease results from ingestion of the parasite, Saracocystis neurona, which contaminates the horse's natural environment; therefore, horses are likely to come in contact with the parasite while eating or drinking. Not all horses that encounter S. neurona develop neurologic disease, some will be protected by their immune system with the only evidence of exposure being serological antibodies. In efforts to not experimentally induce EPM in horses, an immunocompromised mouse model is often used instead. Through the use of the immunocompromised mouse model, researchers have discovered that the immune cell, T lymphocytes, and signaling molecule, interferon gamma, are important for protection against S. neurona infection. In one study conducted for this dissertation it was found that T lymphocytes need to be able to produce interferon gamma in order to provide protection. Another issue that the immunocompromised mouse model has helped address, is EPM treatment efficacy. The inability of antiprotozoal drugs that are utilized for EPM treatment to fully eliminate the parasite from the horse's body is thought to cause reoccurring disease in some horses. One non-FDA approved treatment was evaluated here and determined not to be effective in the immunocompromised mouse model. One FDA approved treatment option, which is commonly used to treat EPM, was evaluated as well. This drug was proven to be effective at preventing disease while mice were being treated but termination of treatment led to development of neurologic disease, exemplifying treatment failure. One final study was conducted to examine the different types of immune cells and signaling molecules in spinal cord tissue samples collected, from horses which had to be euthanized due to poor prognosis related to EPM. In this study a novel experimental technique was successfully used which will help progress EPM research. Overall results of these studies offered more explanation on the immune response that protects against neurologic disease from S. neurona infection and demonstrated that not all treatments are effective and reoccurring disease may be a result of treatment failure.

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Semiconductor superlattices and alloys based on III-V semiconductors have important applications in the design of optoelectronic devices in particular photodetectors. Understanding the electronic properties of such system is critical to be able to properly design and optimize the performance of such devices. Atomistic modelling is the most suitable approach to understand the microscopic properties of these systems. While density functional theory (DFT) is the approach of choice for many studies, it cannot be applied to systems comprised of a large number of atoms. The goal of this thesis is to explore the possibility of applying the empirical pseudopotential method associate with hybrid pseudopotential method to compute the electronic structure and optical properties of Ga_xAl_1-xAs alloy. The proposed work will address first the derivation of portable continuous screened atomic pseudopotentials for the constituent atoms. These will be validated using calculation on small systems. Subsequently, the atomic pseudopotential will be used to study Ga_xAl_1-xAs alloy with different microstructure.

The neurobiology of anxiety-related disorders is associated with impaired neuroplasticity. The glutamate/NO/cGMP pathway has been proposed to play a key role in neuroplasticity and neurodevelopment. It was demonstrated in recent reports that chronic co-administration of the phosphodiesterase type 5 (PDE5) inhibitor sildenafil and the antimuscarinic agent atropine exerts antidepressive-like activity in rats, and that this effect is related to PDE5 inhibition, with consequent elevation of cGMP levels and enhanced protein kinase G stimulation. The current study investigated possible anxiolytic effects of the chronic co-administration of sildenafil and atropine in stress-sensitive Flinders Sensitive Line (FSL) rats. FSL rats received vehicle control, fluoxetine (15 mg/kg), atropine (1 mg/kg), sildenafil (10 mg/kg) or sildenafil plus atropine via intraperitoneal administration, either acutely 30 minutes prior to testing (acutely) or daily for 14 days (chronically). FRL control rats received only vehicle. Thereafter anxiety-like behaviour was evaluated in the social interaction test (SIT - acute) and elevated plus maze (EPM - acute and chronic). The current study also compared to different ways to score the EPM, namely the percentage time spend in the open arms of the EPM and both the number of full and half body open arm entries, and also implemented defecation on the EPM as a measure of anxiety. Vehicle-treated FSL rats exhibited more anxiety-like behaviour than FRL rats in both the SIT and EPM following acute treatment, and in the EPM following chronic treatment. Acute treatment with fluoxetine exerted anxiogenic activity in the SIT and EPM, but anxiolytic activity following chronic administration, as observed in the EPM. In acute treatments neither sildenafil nor sildenafil plus atropine yielded any significant effects on anxiety-like behaviour. However, following chronic treatment, sildenafil exerted anxiolytic activity in the EPM by increasing the time spend in the open arms (45.72% ± 9.94% vs. 20.80% ± 9.94%, P<0.001). Atropine exerted a small anxiolytic response (30.71% ± 8.40% vs. 20.80 ± 9.94%), whereas atropine co-administration was additive to sildenafil alone and yielded an enhanced anxiolytic effect in the elevated plus maze (59.56% ± 4.95% vs. 20.80% ± 9.94%, P<0.001), relative to vehicle control. The percentage time spend in the open arms was scored in the EPM, the results suggested that the chronic treatment with sildenafil plus atropine exert an anxiolytic-like effect in FSL rats and the number of fecal droppings did not increase which is also an indication of an anxiolytic-like effects of the treatment. The current study demonstrated that the chronic treatment with sildenafil, alone or in combination with atropine, exhibit an anxiolytic-like action in stress-sensitive rats. In addition, the data support the clinical potential of using PDE5 inhibitors as antidepressant and anxiolytic strategy and warrant further investigation. Furthermore the study supports the previously proposed key role of the glutamate/NO/cGMP pathway in the neurobiology of anxiety-like disorders, and as an important target for drug development. / Thesis (M.Sc. (Pharmacology))--North-West University, Potchefstroom Campus, 2011

Xenoliths are pieces from the surrounding bedrock, brought to the surface of the earth by host magma. On Gran Canaria, the largest island in the Canary Islands archipelago, strange xenoliths have been found. They are light in color, porous and very different from the basaltic magma carrying them. By studying petrological features and oxygen isotope content of the xenoliths, the focus of this report will be to investigate their origin. The minerals and texture of 14 samples were studied in thin section, and the δ18O–value was determined for 17 samples. The mineralogical composition of xenolith glass was examined by EPMa. The results show that the xenoliths are rich in silica rich glass, quartz and feldspars, but also have high calcium content. 9 of 14 xenoliths have textures and δ18O–values from 8.1 ‰ to 16.77 ‰, similar to sedimentary rocks. The remaining xenoliths are metamorphosed and exhibit altered phenocrysts, indicating they have been melted and recrystallized. The latter group also has extremely low δ18O–value, which could be explained by the effects of hydrothermal processes. Most likely all the xenoliths originate from the prevolcanic sedimentary deposits beneath Gran Canaria.

Constructed wetland (CW) system is one natural purifying process. Using the CW systems to treat industrial wastewater or domestic sewage has been extensively application in many countries. Constructed wastewater treatment wetland must depend on the optimal operation parameters to achieve the best treatment efficiency. The objective of this research was to evaluate the effectiveness of Kaoping River Rail Bridge Constructed Wetland (KPCW) on contaminated river water treatment. The major influents came from the treated industrial wastewater from a paper mill [Yuen Foong Yu paper manufacturing company (System A)] and local drainage system (Chu Liao River) containing untreated domestic wastewater (System B).Results from this study show that the measured flow rates for Systems A and B systems were 10,968 and 13,147 m3/day, respectively. The hydraulic loading rates (HLR) and hydraulic retention time (HRT) for Systems A and B were 0.085 and 0.096 m/day, and 5.4 and 10.7 d, respectively. The average removal efficiencies for both systems ranged from 63.4-71.7% for biochemical oxygen demand (BOD), 39.5-44.4% for chemical oxygen demand (COD), 28.1-39.5% for ammonia nitrogen (NH4-N), 17.1-40.3% for total nitrogen (TN), 5.4-45.5% for total phosphorus (TP), and 91.1-98.7% for total coliform (TC). Reduction in suspend solid (SS) concentration was ineffective in both systems. This was due to the irregular harvest of the plants in the wetland. Results from the effluent probability method (EPM) evaluation indicate that the removal efficiency increased with the increase in influent pollutant concentration. Moreover, variations in pollutant loading rate (PLR) would affect both the removal rates and effluent concentrations. The experience obtained from this project will be helpful in designing similar natural water treatment systems for river water quality improvement for other river basins.

The neurobiology of anxiety-related disorders is associated with impaired neuroplasticity. The glutamate/NO/cGMP pathway has been proposed to play a key role in neuroplasticity and neurodevelopment. It was demonstrated in recent reports that chronic co-administration of the phosphodiesterase type 5 (PDE5) inhibitor sildenafil and the antimuscarinic agent atropine exerts antidepressive-like activity in rats, and that this effect is related to PDE5 inhibition, with consequent elevation of cGMP levels and enhanced protein kinase G stimulation. The current study investigated possible anxiolytic effects of the chronic co-administration of sildenafil and atropine in stress-sensitive Flinders Sensitive Line (FSL) rats. FSL rats received vehicle control, fluoxetine (15 mg/kg), atropine (1 mg/kg), sildenafil (10 mg/kg) or sildenafil plus atropine via intraperitoneal administration, either acutely 30 minutes prior to testing (acutely) or daily for 14 days (chronically). FRL control rats received only vehicle. Thereafter anxiety-like behaviour was evaluated in the social interaction test (SIT - acute) and elevated plus maze (EPM - acute and chronic). The current study also compared to different ways to score the EPM, namely the percentage time spend in the open arms of the EPM and both the number of full and half body open arm entries, and also implemented defecation on the EPM as a measure of anxiety. Vehicle-treated FSL rats exhibited more anxiety-like behaviour than FRL rats in both the SIT and EPM following acute treatment, and in the EPM following chronic treatment. Acute treatment with fluoxetine exerted anxiogenic activity in the SIT and EPM, but anxiolytic activity following chronic administration, as observed in the EPM. In acute treatments neither sildenafil nor sildenafil plus atropine yielded any significant effects on anxiety-like behaviour. However, following chronic treatment, sildenafil exerted anxiolytic activity in the EPM by increasing the time spend in the open arms (45.72% ± 9.94% vs. 20.80% ± 9.94%, P<0.001). Atropine exerted a small anxiolytic response (30.71% ± 8.40% vs. 20.80 ± 9.94%), whereas atropine co-administration was additive to sildenafil alone and yielded an enhanced anxiolytic effect in the elevated plus maze (59.56% ± 4.95% vs. 20.80% ± 9.94%, P<0.001), relative to vehicle control. The percentage time spend in the open arms was scored in the EPM, the results suggested that the chronic treatment with sildenafil plus atropine exert an anxiolytic-like effect in FSL rats and the number of fecal droppings did not increase which is also an indication of an anxiolytic-like effects of the treatment. The current study demonstrated that the chronic treatment with sildenafil, alone or in combination with atropine, exhibit an anxiolytic-like action in stress-sensitive rats. In addition, the data support the clinical potential of using PDE5 inhibitors as antidepressant and anxiolytic strategy and warrant further investigation. Furthermore the study supports the previously proposed key role of the glutamate/NO/cGMP pathway in the neurobiology of anxiety-like disorders, and as an important target for drug development. / Thesis (M.Sc. (Pharmacology))--North-West University, Potchefstroom Campus, 2011

The aim of this study was to investigate whether daily handling in the form of tactile stimulation can ifluence behaviour of adult common voles (Microtus arvalis). The voles were tested in three types of behavioural experiments - Acoustic startle test, Open Field test (OFT), and Elevated Plus Maze test (EPM). No significant impact of handling on personality traits was detected.

<I>Neospora hughesi</I> is a recently described cause of equine protozoal myeloencephalitis (EPM). In the present study, we examined the susceptibility of BALB/c gamma-interferon gene knockout (gamma-INFKO), BALB/c, CD-1, and C57BL/6 strains of mice and gerbils to infection with tachyzoites of the Nh-A1 strain of <I>N. hughesi</I>. Only the gamma-IFNKO mice developed severe clinical disease following infection with <I>N. hughesi</I>. The most severe lesions were in the hearts of these mice. Two dogs fed the brains of mice, shown to contain <I>N. hughesi</I> tissue stages by cell culture and g-IFNKO mouse bioassay, did not shed <I>N. hughesi</I> oocysts over a 23 day observation period. We report important differences between the nucleotide and deduced amino acid sequences of the dense granule proteins GRA6 and GRA7 of <I>N. hughesi and N. caninum</I>. The newly defined proteins of <I>N. hughesi</I> are referred to as NhGRA6 and NhGRA7. From analysis of the sequences we found that there is a 14.8% difference in deduced amino acid sequence between NhGRA7 and NcGRA7, and a 4% difference between NhGRA6 and NcGRA6 in areas that could be compared. This thesis supports the identification of <I>N. hughesi</I> as a separate species from <I>N. caninum</I> and describes novel methods of distinguishing between the two. / Master of Science

Call Centres represent one of the fastest growing industries today. In a competitive business environment the service delivered by Call Centre operators needs to be quantified and this is achieved through Electronic Performance Monitoring (EPM). This study considered the effects of EPM, and related factors such as job control, task complexity, performance, goal-setting and feedback, on the job satisfaction, organisational commitment and work stress, of Call Centre operators. The impact of these factors on staff turnover, which media reports suggest is very high for many Call Centres, was also considered. A total of 388 participants (265 females, 123 males) completed a voluntary self-report questionnaire. All participants were Call Centre operators who were working in one of 27 call centres across Australia in a variety of industries, including Banking & Finance, IT, Employment, Insurance and Telecommunications. All operators were working in an electronically monitored environment. Regression and path analyses revealed age, that is younger employees, and job dissatisfaction to be the only variables that predicted staff turnover. A positive perception of EPM was predicted by a positive perception of both goal-setting and feedback. It was concluded that while staff turnover was high in the current sample, it was not associated with perceptions of EPM, and other factors appeared to be more important.