Introduction: Sub-Saharan Africa remains the region worst affected by the HIV/AIDS pandemic in the world. South Africa (SA) is the country with the highest population of people living with HIV/AIDS in the world and Mpumalanga province is the province with the second highest prevalence of HIV/AIDS in SA. The district of Gert Sibande has the highest prevalence in the province of Mpumalanga (38.9%) in 2006. Since many patients living with HIV/AIDS usually present to district hospitals as the first point of contact it is important to understand the implications of HIV/AIDS in a resource limited health system. Study setting: The setting for this study was Amajuba Memorial Hospital (AMH) a district hospital in the Gert Sibande district of the Mpumalanga province. Objective: To analyse direct costs of providing inpatient care to adult patients with HIV/AIDS-related illnesses at AMH from the perspective of the provider (hospital) Study methods: The population of study comprised adult patients with HIV/AIDS-related illnesses admitted to the medical wards during the period of October 2009 and March 2010 at AMH. A detailed retrospective record review of patients admitted to the adult wards at AMH with HIV/AIDS-related illnesses over a 6-month period was conducted. After the record review the costs were estimated using standard costs and utilisation. Demographic and clinical patient profiles were determined then descriptive statistics were calculated with total costs as an outcome variable. Subsequently univariate and multivariate regression analysis were performed. Results: The demographic and clinical profiles revealed that most patients admitted with HIV/AIDS-related illnesses were: between the ages of 39 & 49 years (35.3%), male (54.9%), urban residents (82.0%), unemployed (87.2%), single (80.5%), were not on HAART (70.7%), had CD4 counts between 0 & 50 x 106 /L (38.3%), had pulmonary tuberculosis (PTB) (38.4%), were admitted for the first time (60.9%) and of the total admitted to hospital 79.0% survived the index admission during the study period. Descriptive statistics of the continuous data variables were determined. Minimums, maximums, inter-quartile ratios, means and modes were determined and tabulated. 5 Consultation costs followed by investigation costs were the two major contributors to total admission costs (77.7% of the median total admission cost). Univariate analysis revealed these significant associations with total admission costs: admission diagnosis, discharge diagnosis, first admission, outcome, pre-admission consults and preceding admissions. In multivariate regression, admission diagnosis and pre-admission consults were analysed. Significant associations were found between the following categories: retroviral disease versus other diseases (p=0.001), retroviral disease versus anaemia (p=0.035), no pre-admission consults versus 1 pre-admission consult (p=0.007), no pre-admission consult versus 4 pre-admission consults (p=0.039) and no pre-admission consult versus 5 or more pre-admission consults (p=0.006). Conclusion: In our study we successfully determined demographic and clinical profiles of patients admitted with HIV-related illnesses at AMH. Emerging from the results of our study were patterns of burden of HIV disease, health seeking behaviour and risky sexual behaviour that all had implications for admission costs in the hospital. Major cost drivers were consultation and investigation costs, which were increased significantly by disease categories; other diseases, anaemia and PTB. Pre-admission consults emerged as a cost reducing parameter in our study. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Clinical Epidemiology / unrestricted

Many econometric analyses of commodity futures over the years have been performed using spot or front month contract prices. Using such daily prices without the consideration of the associated contract traded volumes is slightly erroneous because, in reality, traders will typically trade the ‘most liquid’ contract, that is, the contract with the largest average daily volume (ADV). The reason for this is in order to gain the best price when buying or selling. If this ‘true’ time series is to be considered, a mapping procedure is required to account for the price jumps at the time when a trader trades out of the expiring contract and enters the new front month contract. A key finding was that this effect was significant, irrespective of the size of the price jump, sometimes referred to as basis or roll and also due to the accumulated roll over a number of years corresponding to multiple contracts. It was also found that the mapping procedure has a significant effect on the time series and should hence always be employed if the realistic traded time series is to be considered. Given this phenomenon, algorithmically-traded commodities futures must necessarily employ such time series when creating metrics or considering an econometric analysis. The key findings include the importance of diversification in algorithmically-traded portfolios, utilising the AOM and PSI metrics. The mapping of data sets to create realistic ‘live-traded’ time series was found to be significant, while the optimal day of roll over prior to contract expiry was found to be related to the trading volumes for certain commodities. Other key findings include the causalities and spillovers within the metals sector where various relationships are evident once the results were processed and analysed, both pre and post mapping. Interestingly, the key relationships including bidirectional volatility and shock spillovers between the four key metals existed when the unmapped data was used however, many of the feedbacks within these relationships was lost when the mapped data sets were considered. A significant finding was therefore the consistent differences in findings between mapped and unmapped data sets attributed to the optimisation or favourability of the models (whether econometric or algorithmic). This is due to the unmapped data including roll or basis (which the models are fitted to) taking into account the roll or basis and utilising them in finding relationships between data sets. In the mapped data set (the time series seen by traders) the roll or basis is accounted for and hence the relationships found stand in real-time trading situations. The differences in the results show how the effect of mapping can be significant with unmapped data sets displaying results which will not exist in a real time traded time series.

This diploma aims to analyze the development of the European Union Member States for last thirty years in terms of demographic indicators. First chapter is focused on the historical development of the world's population, followed by the development of the European population and political history of the European Union. Next chapter is focused on the most commonly used demographic indicators for international comparisons divided into groups according to demographic processes, their interpretation and calculation. The main part of the work is analysis of selected indicators for the Member States of the EU with regard to the European average of 27 Member States in the period between 1981 and 2011. Another chapter is devoted to modify data for above mentioned simple analysis and cluster analysis, which is located in the last chapter. Cluster analysis was performed using Euclidean distance and using nearest and furthest neighbor and Ward's method. In 1981 the furthest neighbor method divided Member States into five clusters and in 2011 the Ward's method divided Member States again within five clusters, but with a different composition. Original data for Multidimensional description is added to annex with the results of calculations and graphs.

Please read the abstract in the section front of this document / Dissertation (MSc (Mathematical Statistics))--University of Pretoria, 2009. / Statistics / unrestricted

The rapid growth of the world's urban population shows that people are increasingly moving to cities. In recent decades, the frequent occurrence of smog caused by increasing industrialization has brought environmental pollution to record highs. Therefore, the need to develop forecasting models about air quality occurs when the ambient air contains gasses, dust particles, smoke or odors in quantities large enough to be harmful to organic life. Accurate forecasts help people anticipate environmental conditions and act consequently to decrease dangerous pollution levels, reducing health impacts and associated costs. Rather than investigating deterministic models that attempt to simulate physical processes and develop complex mathematical simulations, this paper will focus on statistical methods, studying historical information and extracting information from data patterns. In looking for new reliable air quality forecasting methods, the goal was to develop and test an artifact based on the Transformer architecture, a novel technique initially developed for natural language processing tasks. Testing was performed against recurrent and convolutional, well-established deep-learning models successfully implemented in many applications, including time-series forecasting. Two different Transformer models were tested, one using time embeddings in the same manner as proposed in the original paper, while in the second model, the Time2Vec method has been adapted. The obtained results reveal that, even though not necessarily better than reference models, both Transformers could output accurate predictions and perform almost as well as recurrent and convolutional models.

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In the literature, the impact of multinationality on the valuation of multinational companies is heavily debated. To understand this impact on valuation, we need to clarify whether and how multinationality affects systematic risk. For this purpose, we analyze the state of research concerning the impact of corporate multinationality on systematic risk, conducting a systematic literature review of 35 studies and a univariate meta-analysis based on 20 studies. We test the predictions of the upstream–downstream hypothesis and the increasing capital market integration hypothesis on the basis of a meta-regression analysis of 17 studies. Our results provide no empirical support for the upstream–downstream hypothesis. However, they corroborate the capital market integration hypothesis in a more radical manner than expected: whereas multinationality seemed to have a risk-reducing effect until the beginning of the 1990s, since then its impact appears to have shifted. We find a risk-increasing effect for multinationality from 1990 on. Our results have important implications for academic research and managerial practice.

Metabolomics as a field has been used to track changes and perturbations in the human body by investigating metabolite profiles indicating the change of metabolite levels over time and in response to different challenges. In this thesis work, the main focus was on applying multiplatform-metabolomics to study the human metabolome following exposure to perturbations, such as diet (in the form of a challenge meal) and exhaust emissions (air pollution exposure in a controlled setting). The cutting-edge analytical platforms used for this purpose were nuclear magnetic resonance (NMR), as well as gas chromatography (GC) and liquid chromatography (LC) coupled to mass spectrometry (MS). Each platform offered unique characterization features, allowing detection and identification of a specific range of metabolites. The use of multiplatform-metabolomics was found to enhance the metabolome coverage and to provide complementary findings that enabled a better understanding of the biochemical processes reflected by the metabolite profiles. Using non-targeted analysis, a wide range of unknown metabolites in plasma were identified during the postprandial stage after a well-defined challenge meal (in Paper I). In addition, a considerable number of metabolites were detected and identified in lung lavage fluid after biodiesel exhaust exposure compared to filtered air exposure (in Paper II). In parallel, using targeted analysis, both lung lavage and plasma fatty acid metabolites were detected and quantified in response to filtered air and biodiesel exhaust exposure (in Paper III and IV). Data processing of raw data followed by data analysis, using both univariate and multivariate methods, enabled changes occurring in metabolites levels to be screened and investigated. For the initial pilot postprandial study, the aim was to investigate the plasma metabolome response after a well-defined meal during the postprandial stage for two types of diet. It was found that independent of the background diet type, levels of metabolites returned to their baseline levels after three hours. This finding was taken into consideration for the biodiesel exhaust exposures studies, designed to limit the impact of dietary effects. Both targeted and non-targeted approaches resulted in important findings. For instance, different metabolite profiles were detected in bronchial wash (BW) compared to bronchoalveolar lavage (BAL) fluid with mainly NMR and LC-MS. Furthermore, biodiesel exhaust exposure resulted in different metabolite profiles as observed by GC-MS, especially in BAL. In addition, fatty acid metabolites in BW, BAL, and plasma were shown to be responsive to biodiesel exhaust exposure, as measured by a targeted LC-MS/MS protocol. In summary, the new analytical methods developed to investigate the responsiveness of the human plasma and lung lavage metabolome proved to be useful in an analytical perspective, and provided important biological findings. However, further studies are needed to validate these results. / Metabolomik har använts för att spåra förändringar och störningar i kroppens funktioner genom undersökning av metabolit-profiler. I detta avhandlingasarbete har huvudfokus varit på tillämpning av flera olika analytiska plattformar för metabolomikstudier av det mänskliga metabolomet efter exponering för olika kost och avgasutsläpp från biodieselbränsle. De sofistikerade analytiska plattformarna som användes för detta ändamål var kärnmagnetisk resonans (NMR), samt gaskromatografi (GC) och vätskekromatografi (LC) kopplat till masspektrometri (MS). Varje plattform erbjöd unika karakteriseringsmöjligheter med detektion och identifiering av specifika grupper av metaboliter. Användningen av multipattformmetabolomik förbättrade täckningen av metabolomet och genererade kompletterande resultat som möjliggjorde en bättre förståelse av de biokemiska processer som reflekteras av metabolitprofilerna. Med hjälp av breda analyser har ett stort antal okända metaboliter i plasma identifierats under den postprandial fasen efter en väldefinerad måltid (i Paper I). Dessutom har ett stort antal metaboliter påvisats och identifierats i lungsköljvätska efter exponering av biodieselavgaser jämfört med kontollexponering med filtrerad luft (i Paper II). Parallellt med dessa breda analyser har också riktade analyser genomförts av både lungsköljvätska och plasma. Därigenom har bioaktiva lipider detekterats och kvantifieras efter avgasexponering och resultaten har jämförts med filtrerad luft som kontrollexponering (Paper III och IV). Processning av rådata följt av dataanalys, med både univariata och multivariata metoder möjliggjorde screening och fördjupad undersökning av förändringen i metabolitnivåer. I den första pilotstudien av postprandiala nivåer var syftet att undersöka responsen i plasmametabolomet efter en väldefinierad måltid under den postprandiala fasen vid två olika typer av kost. Resultaten visade att oberoende av kosten, så återvände metabolitnivåerna till sina baslinjenivåer tre timmar efter måltiden. Detta togs i beaktande vid exponeringsstudierna för biodieselavgaser, som designades så att dietens inverkan minimerades. Både breda och riktade analyser resulterade i viktiga resultat. Exempelvis så detekterades olika metabolitprofiler i bronkiell sköljvätska (BW) jämfört med bronkoalveolär sköljvätska (BAL), speciellt med NMR och LC-MS. Dessutom resulterade avgasexponering i förändrade metabolitprofiler, observerade med GC-MS, särskilt i BAL. Dessutom uppvisade fettsyrametaboliter i BW, BAL och plasma förändrade halter efter avgasexponering, uppmätt genom en riktad LC-MS/MS-analys. Sammanfattningsvis så visade sig de nya metoderna som utvecklats för att undersöka  förändringar i metabolithalterna i plasma och lungsköljvätska fungera väl ur ett analytiskt perspektiv och resulterade i viktiga biologiska fynd. Fördjupade studier behövs dock för att validera resultaten.

The purpose of this study was to examine the effects of parenting training on the acquisition of parenting skills and its impact on self-esteem of incarcerated mothers. The program under study is the "Mothers Inside Loving Kids" (M.I.L.K.) program, which is a holistic training/visitation program designed for incarcerated mothers.Study participants included 40 volunteer incarcerated mothers at the Virginia Correctional Center for women. The treatment group consisted of 20 participants who were already involved in the "M.I.L.K." program. The comparison group was made up of 20 mothers who were on the waiting list for the program due to the lack of space. All participants were administered a battery of pre-tests and post-tests. Instruments utilized for the study included the Adult-Adolescent Parenting Inventory (AAPI), the Nurturing Quiz, the Index of Self Esteem (ISE), and a participant satisfaction survey.Bivariate analyses were used to test the difference between pre-test and post-test mean scores. Both parametric and non-parametric tests were conducted to determine if change scores revealed significant differences. Using independent t-tests to determine if there were significant differences between treatment and comparison groups on change scores, no significant differences were noted. However, in reviewing the direction of change scores for the two groups, the treatment group did show changes in the desired direction in four areas. Specifically, positive directional change occurred on the "Lack of Empathy for the Child" sub-scale, the "Belief in Corporal Punishment" sub-scale, the "Reversing Family Roles" sub-scale, and on the "Nurturing Quiz."Using the Wilcoxon non-parametric test, one measure revealed statistically significant differences between pre-test and post-test scores. Specifically, participants in the treatment group revealed significantly higher scores on the "Nurturing Quiz" at post-testing from pre-testing (z = -2.81, p = .005). This indicates an overall increase in knowledge about positive child management techniques. No significant pre-test to post-test differences were noted in any of the remaining areas under study. However, positive directional change scores were noted in the three different areas of "Inappropriate Expectations of the Child", "Nurturing", and "Self-Esteem."Overall, the findings suggest that the M.I.L.K. Program training positively impacts parenting techniques. Self-esteem appears more difficult to impact.

Un problème fondamental en géométrie algorithmique est celui du calcul de la topologie d'une courbe plane donnée par son équation implicite. Ce problème peut être vu comme celui du calcul d'un graphe qui approche la courbe et qui possède la même topologie que cette dernière. Une étape importante dans les algorithmes calculant la topologie d'une courbe plane concerne le calcul des points singuliers et points extrêmes (en x) de celle-ci. Ce problème se ramène naturellement à celui de la résolution de systèmes bivariés définis par la courbe et ses dérivées par rapport aux variables qui la définissent. Cette thèse porte sur l'étude, l'élaboration et l'implantation d'algorithmes robustes et efficaces pour la résolution de systèmes définis par des polynômes en deux variables à coefficients entiers. Plus précisément, nous nous somme intéressé au calcul d'une Représentation Univariée Rationnelle des solutions. Une telle représentation est constitué d'un polynôme univarié et de deux fonctions rationnelles qui envois les racines du polynôme univarié sur les coordonnées des points solutions du système. Nous présentons dans un premier temps un algorithme théorique pour calculer la RUR d'un système bivarié qui améliore la meilleure borne de complexité connue d'un facteur d^2, ou d désigne le degré des polynômes de départ, et qui permet d'obtenir une nouvelle borne sur la taille des polynômes de cette RUR. Dans un second temps, nous présentons un algorithme de calcul de RUR efficace en pratique. Cet algorithme, basé sur certain choix aléatoires et sur l'utilisation du calcul multi-modulaire est probabiliste. Nous en présentons une première version Monte-Carlo, puis nous montrons comment tester la correction du résultat ce qui fourni un algorithme Las-Vegas. Cet algorithme est efficace à la fois en théorie et en pratique à en juger par l'analyse de complexité en moyenne et les nombreux tests effectués / A fundamental problem in computational geometry is the computation of the topology of an algebraic plane curve given by its implicit equation, that is, the computation of a graph lines that approximates the curve while preserving its topology. A critical step in many algorithms computing the topology of a plane curve is the computation of the set of singular and extreme points (wrt x) of this curve, which is equivalent to the computation of the solutions of bivariate systems defined by the curve and some of its partial derivatives. In this presentation, we study form theoretical and practical perspectives the problem of solving systems of bivariate polynomials with integer coefficients. More precisely, we investigate the computation of a Rational Univariate Representation (RUR) of the solutions of a bivariate system, that is, a one-to-one mapping that sends the roots of a univariate polynomial to the solutions of the bivariate system. We first present a theoretical algorithm for computing the RUR of a bivariate system that improves the best complexity bound for this problem by a factor d^2 where d denote the degree of the input polynomials and allows to derive a new bound on the size of the polynomials of the RUR. We then present an algorithm for computing a RUR that is efficient in practice. This algorithm, based on some random choices and the use of multi-modular computation is probabilistic. We first present a Monte-Carlo variante of this algorithm, and then show how to transforme the latter into a Las-Vegas algorithm by checking the result for correctness. The complexity analysis as well as the experiment we performed show the efficiency of this algorithm