Antinuclear antibodies (ANA) are used in screening and diagnosis of autoimmune connective tissue disorders including systemic lupus erythematosus (SLE). CNS related disorders are prevalent in SLE patients (–80%) and ANA binds specific sites within the brain. To investigate ANA infiltration across the blood-brain barrier (BBB), an ANA injectable Lewis rat model was created using 3 rat groups (saline, ANA, and ANA with histamine; since histamine promotes BBB permeability). ANA serum levels were tested for all three rat groups and rats injected with histamine demonstrated signs of histadelia. Brain slices were obtained and examined for the presence of ANA using immunofluorescence. ANA infiltration across the BBB was observed in ANA injected groups. Though the ANA and ANA histamine groups were significantly different from controls (p<0.034, p<0.030, respectively), no significance between ANA and ANA histamine groups was observed. This model could further be used to examine BBB permeability and potential drug therapy. / Department of Physiology and Health Science

This research focussed on the following issues: • The underrepresentation of female teachers in educational management posts • The teacher's perception of intrinsic promotional barriers. The investigation into the female teacher's perception of intrinsic promotional barriers as reason for her underrepresentation, was based on a study of available literature. Her femininity and female attitudes are held responsible for her underrepresentation. Documented intrinsic perceptions are • sex roles and sex-role typing • sex-role socialisation • societal stereotyping • psychological expectations • motivation and career expectations • role conflict. The female teacher's perception of intrinsic.barriers, as identified by the study, was empirically verified by means of a structured questionnaire. The study concludes with a summary, deductions and recommendations drawn from the research. Intrinsic promotional barriers that are experienced by the female teacher, include: • Sex roles and the influence of sex-role typing • Role conflict. Intrinsic promotional barriers that were not widely experienced by female teachers were: • Sex-role socialisation • Societal stereotyping • Psychological expectations • Motivation and career expectations. The recommendations were that the principles of equality and non-discrimination should be reinforced, the use of "educator" instead of "teacher" encouraged and an enquiry into extrinsic barriers to promotion, followed by the implementation of a management development programme. / Thesis (MEd)--PU for CHE, 1998

Barrier options are becoming more popular, mainly due to the reduced cost to hold a barrier option when compared to holding a standard call/put options, but exotic options are difficult to price since the payoff functions depend on the whole path of the underlying process, rather than on its value at a specific time instant. It is a path dependent option, which implies that the payoff depends on the path followed by the price of the underlying asset, meaning that barrier options prices are especially sensitive to volatility. For basic exchange traded options, analytical prices, based on the Black-Scholes formula, can be computed. These prices are influenced by supply and demand. There is not always an analytical solution for an exotic option. Hence it is advantageous to have methods that efficiently provide accurate numerical solutions. This study gives a literature overview and compares implementation of some available numerical methods applied to barrier options. The three numerical methods that will be adapted and compared for the pricing of barrier options are: • Binomial Tree Methods • Monte-Carlo Methods • Finite Difference Methods / Thesis (MSc (Applied Mathematics))--North-West University, Potchefstroom Campus, 2013

This research focussed on the following issues: • The underrepresentation of female teachers in educational management posts • The teacher's perception of intrinsic promotional barriers. The investigation into the female teacher's perception of intrinsic promotional barriers as reason for her underrepresentation, was based on a study of available literature. Her femininity and female attitudes are held responsible for her underrepresentation. Documented intrinsic perceptions are • sex roles and sex-role typing • sex-role socialisation • societal stereotyping • psychological expectations • motivation and career expectations • role conflict. The female teacher's perception of intrinsic.barriers, as identified by the study, was empirically verified by means of a structured questionnaire. The study concludes with a summary, deductions and recommendations drawn from the research. Intrinsic promotional barriers that are experienced by the female teacher, include: • Sex roles and the influence of sex-role typing • Role conflict. Intrinsic promotional barriers that were not widely experienced by female teachers were: • Sex-role socialisation • Societal stereotyping • Psychological expectations • Motivation and career expectations. The recommendations were that the principles of equality and non-discrimination should be reinforced, the use of "educator" instead of "teacher" encouraged and an enquiry into extrinsic barriers to promotion, followed by the implementation of a management development programme. / Thesis (MEd)--PU for CHE, 1998

Barrier options are becoming more popular, mainly due to the reduced cost to hold a barrier option when compared to holding a standard call/put options, but exotic options are difficult to price since the payoff functions depend on the whole path of the underlying process, rather than on its value at a specific time instant. It is a path dependent option, which implies that the payoff depends on the path followed by the price of the underlying asset, meaning that barrier options prices are especially sensitive to volatility. For basic exchange traded options, analytical prices, based on the Black-Scholes formula, can be computed. These prices are influenced by supply and demand. There is not always an analytical solution for an exotic option. Hence it is advantageous to have methods that efficiently provide accurate numerical solutions. This study gives a literature overview and compares implementation of some available numerical methods applied to barrier options. The three numerical methods that will be adapted and compared for the pricing of barrier options are: • Binomial Tree Methods • Monte-Carlo Methods • Finite Difference Methods / Thesis (MSc (Applied Mathematics))--North-West University, Potchefstroom Campus, 2013

Lookback option is a well-known path-dependent option where its payoff depends on the historical extremum prices. The thesis focuses on the binomial pricing of the American floating strike lookback put options with payoff at time $t$ (if exercise) characterized by \[ \max_{k=0, \ldots, t} S_k - S_t, \] where $S_t$ denotes the price of the underlying stock at time $t$. Build upon the idea of \hyperlink{RBCV}{Reiner Babbs Cheuk and Vorst} (RBCV, 1992) who proposed a transformed binomial lattice model for efficient pricing of this class of option, this thesis extends and enhances their binomial recursive algorithm by exploiting the additional combinatorial properties of the lattice structure. The proposed algorithm is not only computational efficient but it also significantly reduces the memory constraint. As a result, the proposed algorithm is more than 1000 times faster than the original RBCV algorithm and it can compute a binomial lattice with one million time steps in less than two seconds. This algorithm enables us to extrapolate the limiting (American) option value up to 4 or 5 decimal accuracy in real time.

Cobalt is a commonly known sensitiser in industrial settings and has been classified by the IARC as a possible group (2B) human carcinogen. Workers at a South African base metal refinery are potentially exposed to cobalt in the cobalt packaging area. The respiratory and dermal exposure to cobalt is a possible health risk. Quantifying the exposures levels assists in determining the degree of the risk as well as the management thereof. The objectives of this study were to assess dermal and respiratory exposure of workers at a cobalt packaging area and to assess their skin condition by measuring transepidermal water loss (TEWL) and skin hydration indices. The skin hydration index was measured on the back of the hand, forehead, wrist and palm at the start, during and end of the shift. The TEWL index was measured at the start and end of the shift on the same areas as the hydration index. Ghostwipes was chosen as preferred wipe sampling media to collect dermal and surface samples. Wipe samples were also taken on suspected contaminated workplace surfaces. Respiratory samples were taken by using the Institute of Occupational Medicine (IOM) inhalable aerosol sampler at a flow rate of 2 l/min. Wipes and respiratory samples were analysed for cobalt according to NIOSH method 9102 using inductively coupled plasma–atomic emission spectrometry (ICP–AES). The hydration indices indicated that worker’s skin are slightly dry to normal at the beginning of the shift. Hydration on the wrist increased significantly during the shift. TEWL indices increased significantly on the back of the hand, wrist and forehead during the shift. TEWL indices of the palm showed a low barrier function before the shift and deteriorated further to a very low barrier function at the end of the shift. Significant dermal cobalt loading occurred on the back of the hand, forehead, wrist and palm during the shift. The palm was the most exposed and the forehead least. The barrier function of the skin is most likely to be affected by exposure to cobalt. The skin condition of workers put them at greater risk to develop adverse health effects of cobalt. Workplace surfaces were contaminated with cobalt. Airborne cobalt was visible at different working stations. Cobalt exposure is due to numerous sources in the packaging area, thus contributing to the dermal exposure. Respiratory exposure exceeded the 8 hour occupational exposure limit for most of the workers. The guidance limit for short term exposure was exceeded by half of the workers. It is important to minimise the exposure to cobalt in packaging area. Manifestation of the adverse health effects are usually not visible in the short term, the necessary precautions have to be taken to protect the workers. / Thesis (M.Sc. (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2011.

The aim of this thesis is to investigate the effects of additives, reactive elements and impurities, on the lifetime of thermal barrier coatings. The thesis consists of a number of studies on interface adhesion, impurity diffusion, grain boundary sliding and cleavage processes and their impact on the mechanical behaviour of grain boundaries. The effects of additives and impurity on interface adhesion were elaborated by using total energy calculations, electron localization and density of states, and by looking into the atomic separations. The results of these calculations allow the assessment of atomic level contributions to changes in the adhesive trend. Formation of new bonds across the interface is determined to improve the adhesion in reactive element(RE)-doped structures. Breaking of the cross interface bonds and sulfur(S)-oxygen(O) repulsion is found responsible for the decreased adhesion after S segregation. Interstitial and vacancy mediated S diffusion and the effects of Hf and Pt on the diffusion rate of S in bulk NiAl are studied. Hf is shown to reduce the diffusion rate, and the preferred diffusion mechanism of S and the influence of Pt are revealed to be temperature dependent. Finally, the effects of reactive elements on alumina grain boundary strength are studied. Reactive elements are shown to improve both the sliding and cleavage resistance, and the analysis of atomic separations suggest an increased ductility after the addition of quadrivalent Hf and Zr to the alumina grain boundaries.

INTRODUCTION: The blood brain barrier (BBB), formed by the brain capillary endothelial cells separating the blood from the brain. Furthermore, the brain endothelial cells also express numerous transporter systems which help regulate and maintain the brain microenvironment. The protective function of the BBB and their transporter systems under pathological disease states, including brain tumor, can be an obstacle for the entry of therapeutic agents to the brain. OBJECTIVES: The current study set out to characterize brain tumor-induced alterations of the BBB of a mouse brain tumor model. Studies were performed to address changes in BBB permeability to P-gp dependent solutes using Rhodamine (R800). Furthermore, the use of lysophosphatidic acid (LPA) to modulate BBB permeability was also examined in healthy mice and tumor-bearing mice. METHODS: Tumors were induced by injecting Lewis Lung carcinoma (3LL) cells into the right hemisphere of female Balb/c mice. Changes in BBB permeability were assessed at various stages of tumor development, using both gadolinium contrast-enhanced agent (Gad) and 3H-mannitol. Functional activity of P-gp in the BBB was examined in adult mice following i.v. injection of R800 in the presence and absence of GF120918 (a P-gp inhibitor). Alterations in BBB permeability were characterized in healthy and tumor-bearing mice using a small (Gad) and large (IRdye800cw PEG) vascular permeability agent as well as R800 (changes in P-gp mediated permeability). RESULTS: Median mouse survival following 3LL injection was 17 days. The BBB was largely intact during tumor development with disruptions observed at the later stages of tumor development as indicated by Gad permeability. By inhibiting the function of P-gp with GF120918, the distribution of R800 in the brain increased by 4-fold. The enhancement effect of LPA on BBB permeability occurs within 3-6 minutes of injection with the barrier being restored back to its normal function within 20 minutes. Furthermore, an increased in brain penetration of IRdye800ce PEG and R800 were observed following LPA injection in both healthy and tumo-bearing mice. CONCLUSION: These studies provide the initial proof of concept for the use of BBB modulators including LPA and GF120918 to enhance drug delivery to the brain and the tumor sites.

Cobalt is a commonly known sensitiser in industrial settings and has been classified by the IARC as a possible group (2B) human carcinogen. Workers at a South African base metal refinery are potentially exposed to cobalt in the cobalt packaging area. The respiratory and dermal exposure to cobalt is a possible health risk. Quantifying the exposures levels assists in determining the degree of the risk as well as the management thereof. The objectives of this study were to assess dermal and respiratory exposure of workers at a cobalt packaging area and to assess their skin condition by measuring transepidermal water loss (TEWL) and skin hydration indices. The skin hydration index was measured on the back of the hand, forehead, wrist and palm at the start, during and end of the shift. The TEWL index was measured at the start and end of the shift on the same areas as the hydration index. Ghostwipes was chosen as preferred wipe sampling media to collect dermal and surface samples. Wipe samples were also taken on suspected contaminated workplace surfaces. Respiratory samples were taken by using the Institute of Occupational Medicine (IOM) inhalable aerosol sampler at a flow rate of 2 l/min. Wipes and respiratory samples were analysed for cobalt according to NIOSH method 9102 using inductively coupled plasma–atomic emission spectrometry (ICP–AES). The hydration indices indicated that worker’s skin are slightly dry to normal at the beginning of the shift. Hydration on the wrist increased significantly during the shift. TEWL indices increased significantly on the back of the hand, wrist and forehead during the shift. TEWL indices of the palm showed a low barrier function before the shift and deteriorated further to a very low barrier function at the end of the shift. Significant dermal cobalt loading occurred on the back of the hand, forehead, wrist and palm during the shift. The palm was the most exposed and the forehead least. The barrier function of the skin is most likely to be affected by exposure to cobalt. The skin condition of workers put them at greater risk to develop adverse health effects of cobalt. Workplace surfaces were contaminated with cobalt. Airborne cobalt was visible at different working stations. Cobalt exposure is due to numerous sources in the packaging area, thus contributing to the dermal exposure. Respiratory exposure exceeded the 8 hour occupational exposure limit for most of the workers. The guidance limit for short term exposure was exceeded by half of the workers. It is important to minimise the exposure to cobalt in packaging area. Manifestation of the adverse health effects are usually not visible in the short term, the necessary precautions have to be taken to protect the workers. / Thesis (M.Sc. (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2011.