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The work presented in this thesis describes an investigation into the properties and behaviour of nonlinear optical guest molecules doped into polymeric matrices. The interactions of the guest molecule 2-(N, N dimethylamino)-5-nitroacetanilide (DAN) with a polycarbonate and polymethyl methacrylate (PMMA) host are compared. A detailed characterisation of the two systems is described employing infra red spectroscopy and analysis of the chromophore alignment during electric field poling. The study reveals that hydrogen bond formation between the guest and the polar polycarbonate backbone accounts for the unusually good alignment stability previously reported in the polycarbonate system. The molecular hyperpolarisibility of DAN in PMMA is also measured and the apparent enhancement compared with solution measurements is accounted for by the more polar nature of the polymer environment. A new technique allowing the measurement of the dipole moment of polar molecules doped into thin polymer films is also presented. The technique is demonstrated on a series of zwitterionic chromophores whose measured dipole moments range from 30 to 40 D. Electrochroism measurements are performed to account for aggregation of the monomer species which then permits the first hyperpolarisibility of the molecules to be calculated. The values of dipole moment and hyperpolarisibility are found to be very sensitive to the choice of dielectric cavity shape used when deriving the local field correction factors. The measured values are therefore compared with theoretical calculations and a preferred cavity shape is proposed.

Environmental concerns caused by burning fossil fuel and the safety concerns associated with nuclear power plants have led to increased interest and investment in wind power. Wind penetration in power systems is rapidly increasing world-wide and creating significant impacts on the overall system performance. The impact of wind generation on the overall system performance increases substantially as wind penetration in power systems continues to increase to relatively high levels. It becomes increasingly important to accurately model the wind behavior, the interaction with other wind sources and conventional sources, and incorporate the characteristics of the energy demand in order to carry out a realistic evaluation of system reliability. Analytical methods using annual wind models have generally been used for reliability evaluation of wind integrated power systems. These methods do not recognize the seasonal and diurnal load following capability of wind. In this thesis, the system adequacy indices are first evaluated on an annual and seasonal basis and then a technique is developed to incorporate the diurnal load following capability of wind. Power systems with high wind penetrations are often connected to multiple wind farms at different geographic locations. Wind speed correlations between the different wind farms largely affect the total wind power generation characteristics of such systems, and therefore should be an important parameter in the wind modeling process. Another concern that arises is the lack of time-synchronized data, especially at the planning phase, which limits the capability of system planners to accurately model multiple correlated wind farms using simple analytical methods. A simple and appropriate probabilistic analytical wind model which can be used for adequacy evaluation of multiple wind-integrated power systems is proposed in the thesis. A simple analytical method to develop an approximate wind model of multiple correlated wind farms when time-synchronized wind data is not available is also proposed in the thesis. The methods to incorporate correlations in the adequacy evaluations of wind integrated power systems presented in the thesis are expected to be highly useful for system planners and policy makers as wind penetration continues to increase.

The global apparel market is an increasingly desirable industry sector for many marketers. The apparel retail industry in South Africa has experienced significant growth since the year 2000. In 2009, South Africans spent approximately R57 million on apparel items (Statistics South Africa, 2009). On average, South Africans spend R600 or more per month on apparel, making the apparel industry a very lucrative market. Consumer socialisation is the process by which the youth gain the necessary skills and knowledge that enable them to function as consumers in the marketplace. Consumer socialisation highlights the sources of consumer influences or ‘socialisation agents’ that transfer norms, develop attitudes, motivations and behaviour to the learner. Consumer attitudes, behaviour and skills are acquired through socialisation agents such as parents (father, mother and guardian), peers (brothers, sisters and friends) and the mass media (newspaper, television, radio, magazines) The Generation Y cohort (defined as individuals born between 1986 and 2005) is described as the largest and most profitable consumer group for marketers. Generation Y is a lucrative and growing market segment, particularly for apparel retailers. Apparel includes clothing, shoes, jewellery and cosmetics. Those Generation Y members engaged in tertiary education represent an especially important segment given that tertiary education often translates into higher future earning potential and a higher social status within a community and among peers. The primary objective of this research study was to investigate Generation Y students’ attitudes towards the influence of socialisation agents’ on apparel purchasing intentions in South Africa. The target population used in this research study was defined as full-time Generation Y undergraduate students, aged between 18-24 years, who were enrolled at public higher education institutions (HEIs) in South Africa in 2013. The sampling frame comprised the 23 registered South African public HEIs. A non-probability judgement sample method was used to narrow this sampling frame down to two HEI campuses situated in the Gauteng Province. For this study, a convenience sample of 500 full-time Generation Y students who were registered at these two South African HEI campuses during 2013 was drawn. A self-administered questionnaire was used for the collection of primary data for this research study. Academic staff at each of the two HEIs were contacted and asked if they would assist with the distribution of the survey questionnaire to students during class. The attitude towards the influence of socialisation agents on apparel purchasing intentions was measured based on peers, parents and the media. The outcomes from this research study suggest that Generation Y students do not perceive the influence of socialisation agents (peers/parents/media) as being particularly positive. While there was a significant positive relationship between their perceptions concerning the influence of peers, parents and media on apparel purchasing, none of these socialisation agents were perceived as having a significant influence on the Generation Y students’ monthly apparel spending. In terms of gender differences, males perceived the peer influence to be more important while females perceived the parent influence to be more important. There was no significant difference between males and females concerning the importance of the media influence on apparel purchasing. The analysis of statistical information gathered from this study will be relevant to both marketing practitioners and academia in understanding Generation Y consumers’ attitudes towards the influence of socialisation agents (peers/parents/media) in apparel purchasing intentions. / MCom (Marketing Management), North-West University, Vaal Triangle Campus, 2014

Since the reform in the 1980s, the Chinese electric power industry has experienced rapid expansion in both capacity and outputs, which is surprising since the industry is still under a plan control. The shortage of supply is a common problem in a plan economy according to the conventional wisdom. But China provides very different experience that challenges the wisdom. Why? This thesis attempts to understand why the plan-controlled industry can achieve such rapid growth over a short period of time. The study pursues its investigation through exploring three issues: the price and cost structures, the pricing setting and the capacity expansion with reference to OECD experience. By comparing power prices of China with the West, we find that China has successfully kept its household prices as lower as its industrial prices, while the OECD economies are reverse, a lower power price for the industry but higher for the household users. The finding shows that the plan increases consumers‟ welfare more than the market does. With further investigation to the cost structure of Chinese power plants with reference to the UK experience, we find that the Chinese power producers have lower variable costs than the Western plants, but similar overheads costs. To further explain such finding, we studied a sample of 100 coal-fired power plants from 2003 to 2005 for their pricing behaviour. We find that the firms adopt a high cost strategy to bargain with the state for higher plan prices, because of the one-firm-with-one-plan-price policy. This causes a soft price constraint on costs, which inevitably protects high cost firms, driving up the total costs of the firm, and providing a lower incentive to the firm to improve their cost efficiency. The firms are planned by the state for their outputs. Will the state plan affect the capacity of power supply in favour? The study argues yes, because (1) entry is free and capacity investment is under firm‟s autonomy, (2) the firms are very responsive to capacity utilization and demand in choosing their capacity investment, and (3) the firms seek more profits through seeking more plan outputs that are linked with capacity. Therefore, the firms do not compete in prices but the capacity of power generation. These explain why the reformed plan system works in stimulating capacity growth.

This thesis is concerned with the task of automatically generating captions for images, which is important for many image-related applications. Automatic description generation for video frames would help security authorities manage more efficiently and utilize large volumes of monitoring data. Image search engines could potentially benefit from image description in supporting more accurate and targeted queries for end users. Importantly, generating image descriptions would aid blind or partially sighted people who cannot access visual information in the same way as sighted people can. However, previous work has relied on fine-gained resources, manually created for specific domains and applications In this thesis, we explore the feasibility of automatic caption generation for news images in a knowledge-lean way. We depart from previous work, as we learn a model of caption generation from publicly available data that has not been explicitly labelled for our task. The model consists of two components, namely extracting image content and rendering it in natural language. Specifically, we exploit data resources where images and their textual descriptions co-occur naturally. We present a new dataset consisting of news articles, images, and their captions that we required from the BBC News website. Rather than laboriously annotating images with keywords, we simply treat the captions as the labels. We show that it is possible to learn the visual and textual correspondence under such noisy conditions by extending an existing generative annotation model (Lavrenko et al., 2003). We also find that the accompanying news documents substantially complements the extraction of the image content. In order to provide a better modelling and representation of image content,We propose a probabilistic image annotation model that exploits the synergy between visual and textual modalities under the assumption that images and their textual descriptions are generated by a shared set of latent variables (topics). Using Latent Dirichlet Allocation (Blei and Jordan, 2003), we represent visual and textual modalities jointly as a probability distribution over a set of topics. Our model takes these topic distributions into account while finding the most likely keywords for an image and its associated document. The availability of news documents in our dataset allows us to perform the caption generation task in a fashion akin to text summarization; save one important difference that our model is not solely based on text but uses the image in order to select content from the document that should be present in the caption. We propose both extractive and abstractive caption generation models to render the extracted image content in natural language without relying on rich knowledge resources, sentence-templates or grammars. The backbone for both approaches is our topic-based image annotation model. Our extractive models examine how to best select sentences that overlap in content with our image annotation model. We modify an existing abstractive headline generation model to our scenario by incorporating visual information. Our own model operates over image description keywords and document phrases by taking dependency and word order constraints into account. Experimental results show that both approaches can generate human-readable captions for news images. Our phrase-based abstractive model manages to yield as informative captions as those written by the BBC journalists.

This project examines the implications of the photovoltaic power generation as well as the battery storage systems on the distribution network tariff structures. Different types of existing distribution tariffs were applied to the residential households’ demand patterns. Several scenarios of demand profiles were theoretically investigated. First scenario included households’ consumption under current situation without on-site power production and any storage, second scenario concerned penetration of average size of solar panel installations and the last demand profile with maximum possible size of photovoltaic panels complemented with battery storage use. The distribution tariffs included in the comparison are: power based tariff and two energy based tariffs, one with flat-rate and another with time-of-use structure. Distribution tariffs were normalized with the aim to research the implications of the on-site production and storage use. Normalization factors were used when comparing financial bills from the households under above mentioned scenarios. Energy distribution tariffs have higher potential for households to save on their energy bill with the introduction of the on-site solar power utilization. On the other hand power tariff provides higher incentive for the implementation of the demand response strategies in the households.

Background: Obesity is a metabolic disease caused by environmental and genetic factors. However, the epigenetic mechanisms of obesity are incompletely understood. The aim of our study was to investigate the role of skeletal muscle DNA methylation in combination with transcriptomic changes in obesity. Results: Muscle biopsies were obtained basally from lean (n = 12; BMI = 23.4 +/- 0.7 kg/m(2)) and obese (n = 10; BMI = 32.9 +/- 0.7 kg/m(2)) participants in combination with euglycemic-hyperinsulinemic clamps to assess insulin sensitivity. We performed reduced representation bisulfite sequencing (RRBS) next-generation methylation and microarray analyses on DNA and RNA isolated from vastus lateralis muscle biopsies. There were 13,130 differentially methylated cytosines (DMC; uncorrected P < 0.05) that were altered in the promoter and untranslated (5' and 3'UTR) regions in the obese versus lean analysis. Microarray analysis revealed 99 probes that were significantly (corrected P < 0.05) altered. Of these, 12 genes (encompassing 22 methylation sites) demonstrated a negative relationship between gene expression and DNA methylation. Specifically, sorbin and SH3 domain containing 3 (SORBS3) which codes for the adapter protein vinexin was significantly decreased in gene expression (fold change -1.9) and had nine DMCs that were significantly increased in methylation in obesity (methylation differences ranged from 5.0 to 24.4 %). Moreover, differentially methylated region (DMR) analysis identified a region in the 5' UTR (Chr. 8: 22,423,530-22,423,569) of SORBS3 that was increased in methylation by 11.2 % in the obese group. The negative relationship observed between DNA methylation and gene expression for SORBS3 was validated by a site-specific sequencing approach, pyrosequencing, and qRT-PCR. Additionally, we performed transcription factor binding analysis and identified a number of transcription factors whose binding to the differentially methylated sites or region may contribute to obesity. Conclusions: These results demonstrate that obesity alters the epigenome through DNA methylation and highlights novel transcriptomic changes in SORBS3 in skeletal muscle.

Optically pumped semiconductor vertical external cavity surface emitting lasers (VECSEL) were first demonstrated in the mid 1990's. Due to the unique design properties of extended cavity lasers VECSELs have been able to provide tunable, high-output powers while maintaining excellent beam quality. These features offer a wide range of possible applications in areas such as medicine, spectroscopy, defense, imaging, communications and entertainment. Nowadays, newly developed VECSELs, cover the spectral regions from red (600 nm) to around 5 µm. By taking the advantage of the open cavity design, the emission can be further expanded to UV or THz regions by the means of intracavity nonlinear frequency generation. The objective of this dissertation is to investigate and extend the capabilities of high-power VECSELs by utilizing novel nonlinear conversion techniques. Optically pumped VECSELs based on GaAs semiconductor heterostructures have been demonstrated to provide exceptionally high output powers covering the 900 to 1200 nm spectral region with diffraction limited beam quality. The free space cavity design allows for access to the high intracavity circulating powers where high efficiency nonlinear frequency conversions and wavelength tuning can be obtained. As an introduction, this dissertation consists of a brief history of the development of VECSELs as well as wafer design, chip fabrication and resonator cavity design for optimal frequency conversion. Specifically, the different types of laser cavities such as: linear cavity, V-shaped cavity and patented T-shaped cavity are described, since their optimization is crucial for transverse mode quality, stability, tunability and efficient frequency conversion. All types of nonlinear conversions such as second harmonic, sum frequency and difference frequency generation are discussed in extensive detail. The theoretical simulation and the development of the high-power, tunable blue and green VECSEL by the means of type I second harmonic generation in a V- cavity is presented. Tens of watts of output power for both blue and green wavelengths prove the viability for VECSELs to replace the other types of lasers currently used for applications in laser light shows, for Ti:Sapphire pumping, and for medical applications such as laser skin resurfacing. The novel, recently patented, two-chip T-cavity configuration allowing for spatial overlap of two, separate VECSEL cavities is described in detail. This type of setup is further used to demonstrate type II sum frequency generation to green with multi-watt output, and the full potential of the T-cavity is utilized by achieving type II difference frequency generation to the mid-IR spectral region. The tunable output around 5.4 µm with over 10 mW power is showcased. In the same manner the first attempts to generate THz radiation are discussed. Finally, a slightly modified T-cavity VECSEL is used to reach the UV spectral regions thanks to type I fourth harmonic generation. Over 100 mW at around 265 nm is obtained in a setup which utilizes no stabilization techniques. The dissertation demonstrates the flexibility of the VECSEL in achieving broad spectral coverage and thus its potential for a wide range of applications.

At the rate the population is growing it is important to find ways to be more efficient with the energy and water we use. The increase in population increases the need for electricity and water, but the way we are using our sources will not leave us with enough for future generations. The constant use of "dirty energy", energy that emits CO2 and other chemicals into the atmosphere, will continue to harm our environment. A new system is needed to help preserve water and produce green energy that will not harm the only earth we have.