Cette thèse se concentre sur des aspects de dualités holographiques reliant une théorie gravitationnelle en trois dimensions à une théorie des champs sur le bord de cette espace, c'est-à-dire en dimensions deux. Dans le premier chapitre, nous passons en revue diverses méthodes, utilisées tout au long de la thèse, pour calculer des quantités conservées en théorie de jauge et plus particulièrement en gravitation. Ensuite, dans le deuxième chapitre, nous rappelons le cas d'école des espaces-temps localement anti-de Sitter (AdS) à trois dimensions et de leur théorie duale, les théories des champs conformes en deux dimensions. Les chapitres trois et quatre sont dédiés à la présentation d'espaces-temps non-AdS considérés dans cette thèse et de la dualité dans laquelle ils sont impliqués. Le premier s'intéresse aux espace-temps warped AdS, qui peuvent être vus comme une déformation d'AdS. Leur théorie des champs duale serait une théorie des champs conforme warped. Le second se concentre sur des solutions cosmologiques, localement plates, qui seraient duales à des théories des champs invariantes sous le groupe BMS$_3$ (groupe de symétrie des espaces asymptotiquement plats). Dans le chapitre cinq, nous révisons des notions de thermodynamique que nous utiliserons pour discuter des transitions de phase entre deux géométries appartenant au même espace des phases. Par exemple, entre l'espaces-temps AdS thermique et le trou noir localement AdS. La partie originale de la thèse traite d'abord des solutions maximalement symétriques dans n'importe quelle théorie invariante sous difféomorphisme. Nous prouvons que le calcul d'entropie gravitationnel est reproduit par le comptage asymptotique d'états dans la théorie duale. Ce travail est étendu au cas des espaces-temps warped. Nous montrons également que leur entropie du bulk et du bord sont en correspondance et ce pour toutes théories de gravitation. Ceci constitue une vérification non triviale des correspondances holographiques. Nous étudions aussi leurs transitions de phase. Finalement, nous posons les premières pierres d'une nouvelle correspondance holographique, impliquant une corde noire, en trouvant un ensemble de conditions au bord cohérent. Nous discutons également la thermodynamique des cordes noires. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Magister Scientiae Dentium - MSc(Dent) / Human identification is one of the major responsibilities in the field of Forensic Odontology as it plays a role in identifying deceased individuals using their oral and dental structures. Furthermore, human identification could be a challenging procedure in catastrophic disasters and mass fatality incidents in terms of decomposed and skeletonized human remains. Identification process can be applied using different methods such as fingerprint, DNA and detention. Gender-determination of the victim facilitates reconstruction and rebuilding in the profiling of a medico-legal case investigation. Gender-determination facilitates the procedure up to 50% for positive identification. Anthropology studies have shown that the sexual dimorphism of skeletal remains and teeth can facilitate the identification process. However, teeth are the hardest structures in the human body and virtually immortal as they can withstand diverse circumstances This study aimed to investigate sexual dimorphism of teeth by measuring the mesiodistal width of the maxillary and mandibular permanent canines in a sample of the South African population living in Cape Town. Two hundred orthodontic study models were used, 50 males and 50 females, between 13-30 years of age.

Varje individ har en unik personlighet som påverkar olika livsaspekter. Politisk orientering är en av dessa. Forskning har visat att det finns ett samband mellan personligheten och politisk orientering. Syftet med denna studie var att undersöka relationen mellan HEXACO sex personlighetsdimensioner och politisk orientering samt hur den politiska orienteringen förhåller sig mellan högskolans fyra akademier. Etthundratre studenter deltog i undersökningen. En webbenkät delades ut till högskolestudenterna vilken bestod av 3 demografiska frågor, 60 personlighetsfrågor och 1 fråga som mäter politisk orientering. Resultatet från korrelation och regressionsanalyserna visade att personligheten har ett signifikant samband med politisk orientering där vänsterorienterade studenter tenderar att vara mer empatiska och att högerorienterade studenter visar en strävan efter social status. Studenter i UKK och HVV visade en vänsterorienterad inställning medan IDT och EST en högerorienterad. Totalt kunde 36% av studenters politiska orientering förklaras av demografiska variabler, akademitillhörighet och personlighetdimensionerna. I diskussionen diskuteras resultatet med olika infallsvinklar.

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Machine learning is emerging as a powerful tool to data science and is being applied in almost all subjects. In many applications, the number of features is com- parable to the number of samples, and both grow large. This setting is usually named the high-dimensional regime. In this regime, new challenges arise when it comes to the application of machine learning. In this work, we conduct a high-dimensional performance analysis of some popular classification and regression techniques. In a first part, discriminant analysis classifiers are considered. A major challenge towards the use of these classifiers in practice is that they depend on the inverse of covariance matrices that need to be estimated from training data. Several estimators for the inverse of the covariance matrices can be used. The most common ones are estimators based on the regularization approach. In this thesis, we propose new estimators that are shown to yield better performance. The main principle of our proposed approach is the design of an optimized inverse covariance matrix estimator based on the assumption that the covariance matrix is a low-rank perturbation of a scaled identity matrix. We show that not only the proposed classifiers are easier to implement but also, outperform the classical regularization-based discriminant analysis classifiers. In a second part, we carry out a high-dimensional statistical analysis of linear support vector regression. Under some plausible assumptions on the statistical dis- tribution of the data, we characterize the feasibility condition for the hard support vector regression and, when feasible, derive an asymptotic approximation for its risk. Similarly, we study the test risk for the soft support vector regression as a function of its parameters. The analysis is then extended to the case of kernel support vector regression under generalized linear models assumption. Based on our analysis, we illustrate that adding more samples may be harmful to the test performance of these regression algorithms, while it is always beneficial when the parameters are optimally selected. Our results pave the way to understand the effect of the underlying hyper- parameters and provide insights on how to optimally choose the kernel function.

The access dimensions to the local, urban food environment of adults in the eastern suburbs of the Tshwane metropolitan are explored and described. The study further determined how the food access dimensions contribute to the food choices and food consumption patterns of the study group. South Africa has the highest rate of urbanisation in the world. Moving to and living in urban areas usually result in major shifts in people’s food consumption patterns and lifestyles which are associated with non-communicable diseases. Intervention strategies aimed at changing consumers’ food behaviour often fail to recognise the complexities associated with the local urban food environment and the contribution of the food access dimensions. This study fills the gap on the limited information on the food access dimensions and food choices of white South African urban adults. A mixed methods approach was followed in this cross-sectional study that consisted of two phases. In the first quantitative phase, an electronic survey questionnaire was used to gather information on respondents’ usual food shopping and eating patterns, together with aspects related to the local urban food environment. The questionnaire was completed by a total of 230 white adults residing in regions 3, 4 and 6 of the Tshwane metropolis. The second qualitative data collection phase used Geographic Information System (GIS) measurement to identify, describe and map all the food retail outlets in the eastern suburbs of Tshwane. From the mapped food stores in regions 3, 4 and 6, stores were purposively selected and in-store observations were conducted to gain information and insight into the variety, quality and price of food products on offer in these food retail stores. A food basket was developed to obtain and compare the price of certain food products. Food prices between food stores were compared, as well as with the Consumer Price Index. Results indicated a minimal difference in price and it is concluded that most of the food products seemed to be affordably-priced to adults in Tshwane. Results confirm that urban consumers in Tshwane have easy, adequate access to food stores and purchase most of their food at supermarkets at least once or more times a week. The results also prevailed that a variety of good quality, affordable food products are available and accessible at food stores close to them and that they find the stores accommodating and food products acceptable. Although the Dietary Diversity Score (DDS) of 6.20 reflected that the majority of the respondents daily consumed a variety of food, they do not follow all the guidelines of the Food-Based Dietary Guidelines for South Africa, which might have an impact on their future health. This research contributes to a better understanding of how the access dimensions in the local urban food environment contribute to urban consumers’ food choices. By exploring the local urban food environment of urban consumers in Tshwane, this study contributed to fill the knowledge gap on this topic in South Africa. / Dissertation (MConsumer Science)--University of Pretoria, 2019. / Consumer Science / MConsumer Science / Unrestricted

This study explores the gender differences in how parents exhibit parenting dimensions (control, monitoring, support and warmth) towards sons and daughters and how those dimensions influence contraceptive use. The data analysis uses the Add Health data and the sample includes 918 adolescents within two-parent homes. This study adds to the existing literature in three ways. First, this study investigates four different parenting dimensions whereas previous research focuses on control and communication. Second, this study looks at how each dimension influences contraceptive use. Third, this study examines how parents exhibit parenting dimensions differently towards sons and daughters and whether each dimension influences contraceptive use differently for sons and daughters. The results reveal three significant findings. First, mothers’ and fathers’ parenting dimensions and the dimensions sons and daughters experience are similar. Second, warmth and support influence contraceptive use among sons and daughters. Third, boys are influenced by parenting dimensions more than girls.

<p> A detailed synopsis of the state-of-the-art in the field of the Structural Analysis of sandwich beams is presented. Deficiencies, inaccuracies, lack of clarity, and the imposition of unnecessary assumptions of behaviour found in the related bibliography are presented in a comparative fashion. A method of analysis with obvious advantages over the others studied in this thesis is derived, and its use is suggested. The presentation of all methods of analysis is made under the most general cases of dimensions and loadings to make them as applicable as possible to the common cases encountered in sandwich components for the building industry.</p> <p> Experimental work carried out on several materials with some potential to be used in sandwich members for buildings and the tests carried out on some sandwich beams and beam-columns are reported.</p> / Thesis / Master of Engineering (MEngr)

Background: Since its publication in 1997, Jennifer Aaker’s brand personality model has been challenged but none of the publications have had the same seminal effect. Additionally, differences in perceptions of Aaker’s personalities have been found which suggests a gap of knowledge to research. With the development of social media, customers begin to be more engaged with the brands. Purpose: The goal of this study is to explore European airlines’ brand personalities and Gen Z’s perception of the personalities through brands’ TikTok content by using Jennifer Aaker’s (1997) brand personality dimensions. Additionally, social media engagement is used as a tool to investigate the significance of social media for brands. Method: An exploratory qualitative deductive study, with an exploratory nature and an experimental design, applying semi-structured interview methods with a sample size of 25 participants. Conclusion: The findings demonstrate that Aaker’s personality traits are somewhat still relevant to Gen Z’s perception of them but there are traits that could be added which have been argued for by other scholars as well before. These additional traits should include negative traits and traits that show extroversion and introversion, for instance.

This research answers the complex decision-making question about identifying the quality dimensions in a polymer industry and to prioritize these quality dimensions to obtain the best quality product with minimum expenditure. This research takes use of expert opinion and right decision-making model to yield an optimal solution which will help the manufacturing plants to reduce wastage and to get a better consistent quality product throughout the production process.