Background: Analyses of the individual-, social- and structural-level factors promoting the transmission of HIV and other blood-borne pathogens have consistently identified exposure to correctional environments, especially for individuals who use injection drugs (IDU), as a risk factor for infection. The objectives of this project were: to review the epidemiologic literature on incarceration and HIV infection among IDU, critically examining evidence presented supporting a causal linkage between imprisonment and infection; to investigate incarceration experiences in a cohort of active IDU; and to assess the possible effects of incarceration on the post-release risk environment of active IDU. Methods: Longitudinal datasets for quantitative analyses were derived from the Vancouver Injection Drug User Study (VIDUS) and the Scientific Evaluation of Supervised Injection (SEOSI), both prospective cohorts of IDU in Vancouver’s Downtown Eastside neighbourhood. In the first analysis, the prevalence and correlates of reporting incarceration in the the previous six months were identified in SEOSI using generalized estimating equations (GEE). In the second analysis, the possible effect of imprisonment on the prevalence of risk factors for HIV infection was estimated in VIDUS using linear growth curve analysis. Results: In the first analysis, 902 individuals interviewed at least once between 1 July 2004 and 30 June 2006 were included. Overall, 423 (46.9%) reported an incarceration event at some point during the study period. In a multivariate GEE model, recent incarceration was independently associated with a number of high-risk factors, including syringe sharing. In the second analysis, 1603 individuals were interviewed at least once between 1 May 1996 and 31 December 2005 and in cluded. Of these, 147 (9.2%) matched the study criteria and were included as cases; 742 (46.3%) were included as matched controls. In linear growth curve analyses adjusted for age, gender and ethnicity, syringe sharing was significantly more common in the incarcerated group (p = 0.03) after incarceration than in the control group. Conclusions: Our findings support the existence of a role for incarceration in continued viral transmission. In response, appropriate harm reduction measures should be expanded within correctional environments and social, political and legal reforms enacted to reduce the incidence of imprisonment for individuals who use illicit drugs. / Medicine, Faculty of / Population and Public Health (SPPH), School of / Graduate

The resolution of differential equations of diverse degree of complexity is necessary to simulate the phenomena present in the complex turbomachinery flows and in particular, requires accounting for unsteady effects that may have a preponderant role. Today, only the LES (Large Eddy Simulation) fully compressible approach has the required accuracy to predict the physics associated to reactive and turbulent flows in such complex geometries. This work covers the numerical modelling of physics in the near-wall region of a high-pressure turbine blade with special focus on thermal predictions. This work was supported by the European project COPA-GT, dedicated to the numerical multi-physics simulation of a complete gas turbine.

Web application vulnerabilities of critical are commonly found in web applications. The arguably most problematic class of web application vulnerabilities is SQL injections. SQL injection vulnerabilities can be used to execute commands on the database coupled to the web application, e.g., to extract the web application’s user and passwords data. Black box testing tools are often used (both by system owners and their adversaries) to discover vul- nerabilities in a running web application. Hence, how well they perform at discovering SQL injection vulnerabilities is of importance. This thesis describes an experiment assessing de- tection capability for different SQL injection vulnerabilities under different conditions. In the experiment the following is varied: SQL injection vulnerability (17 instances allowing tautologies, piggy-backed queries, and logically incorrect queries), scanners (four products), exploitability (three levels), input vector (POST/GET), and time investment (three levels). The number of vulnerabilities detected is largely determined by the choice of scanner (30% to 77%) and the input vector (71% or 38%). The interaction between the scanner and input vector is substantial since two scanners cannot handle the POST-vector at all. Substantial differences are also found between how well different SQL injection vulnerabilities are de- tected and the more exploitable variants are detected more often, as expected. The impact of time spent with the scan interacts with the scanner - some scanners required considerable time to configure and other did not – and as a consequence the relationship between time investments to detection capabilities is non-trivial.

Sequential injection analysis (SIA) that was developed in 1990 is a simple, versatile and automated technique based on precise aspiration of small volumes of reagents and samples into a single channel. It is economical in terms of reagent consumption and waste generation. SIA is applied to food, environmental and pharmaceutical samples. SIA parameters and the chemical variables are optimized and figures of merit are reported. Spectrophotometer has been used as a detector in the analysis of formaldehyde (HCHO), ascorbic acid and ferric iron (Fe (III)). A stopped flow method was adapted to SIA spectrophometric technique. Enhanced sensitivity was obtained using a stopped flow method as compared to a non-stopped flow method. The SIA spectrophotometric determination of Fe (III) through complex formation with the thiocyanate and the Tiron reagents has been studied in chapter 3. The two methods were compared based on convenience, sensitivity, simplicity, reliability and on general application. Both methods are simple, employ readily available reagents and have lower detection limits and shorter analysis time of 72 samples per hour. The thiocyanate method enabled the determination of Fe (III) in the linear range of 2 to 50 mg/ℓ with a detection limit of 0,2 mg/ℓ whereas the Tiron method provided a linear range of 1 to 50 mg/ℓ with a detection limit of 0,1 mg/ℓ. Chapter 4 presents the application of SIA spectrophotometric method for the determination of formaldehyde in wastewater. The method is based on the inhibition of brilliant green-sulfite reaction by formaldehyde. The kinetic method was implemented by stopping the flow when the complex reaches the detector and the measurements were taken as the reaction proceeds. The SIA method was compared with the chromotropic acid method and the paired t-test was used to determine whether the results obtained by the two methods differ significantly. Good sensitivity with a detection limit of 0,06 mg/ℓ and a wider linear range of 1-3 mg/ℓ was achieved. Chapter 5 describes the indirect determination of ascorbic acid in pharmaceutical samples, sweets and beverage (orange juice). This method is based on reduction of Fe (III) to ferrous iron (Fe (II)) by ascorbic acid under UV-light irradiation and the reaction of generated Fe (II) with 1,10-phenanthroline. The flow was stopped in the holding coil for a defined time to ensure that complete reduction process take place under irradiation. Photochemical reaction methods improved the sensitivity with detection limit of 0,06 mg/ℓ. Good precision was obtained with relative standard deviation of 1,3 %. The method compared well with the N-bromosuccinimide titration method. The versatility and simplicity of SIA technique makes it suitable to different requirements of various analytical problems. / Dissertation (MSc (Chemistry))--University of Pretoria, 2007. / Chemistry / MSc / unrestricted

Interest in the automation of titration arise from the fact that many acid-base titrations in the process industries rely on manual titration which is time consuming. Miniaturization of these titration processes becomes attractive because of the reduced reagent consumption. These industries must produce higher quality products economically and in a friendly environment. Due to its ease of automation, ability to handle concentrated solutions and simplicity, the application of sequential injection titration is an ideal tool in process effluent streams, food industries, beverage industries and production plants. The sequential injection titration system was optimised with respect to all instrumental parameters of the system and applied for acid-base titrations. The results obtained showed high reliability and reproducibility. The system is fully computerised, inexpensive and suitable for on-line monitoring. / Dissertation (MSc (Chemistry))--University of Pretoria, 2006. / Chemistry / unrestricted

The concept of sequential injection analysis (SIA), introduced as a simple and convenient principle, has established itself as a well defined analytical technique suitable for routine laboratory analysis. This technique is fully computerized and reliable with a reasonable sample frequency, low sample and reagent consumption and low frequency of maintenance. In pharmaceutical based analysis SIA can be used at each step through the entire production process, from raw material to the final consumer product. With its substantial advantages, an SIA system can replace sophisticated instrumentation facilities, which are unlikely to be used for manufacturing environments. The aim of this study was to investigate the application of the sequential injection analysis technique in the determination of selected substances of biological importance from the pharmaceutical industry (zinc, paracetamol and boron). It is important to control the level of zinc and boron in human, animals and plants. Overdose of paracetamol is a problem in our body. That is why the uniformity tests of paracetamol must be very accurate and precise. The aim was successfully achieved. The results obtained for all substances proved the high reliability of the SIA technique. / Dissertation (MSc (Chemistry))--University of Pretoria, 2006. / Chemistry / unrestricted

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Ce travail de thèse présente la caractérisation expérimentale de fibres de lins et une modélisation de l’écoulement de résine lors du procédé de Resin Transfer Molding (RTM) utilisant ces mêmes fibres. La variation du diamètre des filaments de lins immergés dans différents liquides tests est caractérisée par observation au microscope. Le taux et la vitesse d’absorption de liquides tests dans les fibres sont ensuite obtenus par centrifugation. Un nouveau modèle de perméabilité est ainsi développé afin de prendre en compte les effets du gonflement des fibres sur la perméabilité quelque soit le liquide test considéré. Le modèle est validé après comparaison avec les perméabilités expérimentales. Les propriétés de mouillage des fibres de lin en présence de différents liquides tests sont mesurées en utilisant un tube capillaire et une mèche de fibres de lin. Un modèle prenant en compte le gonflement des fibres ainsi que le phénomène d’absorption est proposé pour déterminer la tension de surface et l’angle de contact décrivant la mouillabilité. L’écoulement insaturé dans le tissu de fibres de lin est modélisé en utilisant l’équation de conservation de la masse, la loi de Darcy ainsi que les modèles de gonflement et d’absorption précédemment définis. Le flux massique absorbé dans les fibres et la modification du taux local de fraction volumique sont introduits par l’intermédiaire de termes puits dans l’équation de conservation de la masse. La variation de perméabilité spatiale et temporelle non uniforme peut ainsi être considérée dans le modèle complet proposé. Ce modèle est validé par comparaison avec un suivi expérimental de l’écoulement dans une préforme de fibres de lin. / This thesis presents an experimental characterization of flax fiber and a modeling of the resin flow during the resin transfer molding process with flax preform. The change of diameter of flax fiber filament immersed in different test liquids was characterized using optical microscope. The sorption rate of the resin mass into the fiber filament immersed in the test liquids was also experimentally characterized using centrifuge test. A new permeability model was proposed to predict the permeability taking into account the fiber swell effect, regardless of test liquid and the model was validated by a comparison with the experimental measurement data. The wetting properties of flax fiber in contact with different test liquids were measured by capillary rise test using flax fiber yarn and a new model was established to obtain surface tension and contact angle by considering the fiber swell effect and the liquid sorption into the fiber filament. The unsaturated resin flow in the flax fiber preform was modeled by modifying the conventional mass conservation equation and Darcy’s law in order to take into account the effects of fiber swell and liquid sorption. The mass rate absorbed into the fiber and the change of fiber volume were considered as sink terms in the mass conservation equation. The permeability change due to the fiber swell was modeled in terms of time of fiber’s immersion in liquid. In particular, the sink term and permeability were considered as spatially and temporally non-uniform in the flow model. The proposed model was validated by a comparison with the experimental measurement of flow advancement in the flax fiber preform.

This thesis describes the design of injection form for production of plastic lever. In the introduction,there is general literary studies of plastics and injection molding technology. Then continues studies of the injection molding machine, injection form or by selecting the gating systém. The practical part is injection mold design which includes a calculation of the injectionparameters, selection of equipment and technical and economic evaluation.

This master´s thesis addresses the design of technology manufacturing plastic parts. The first part deals with the study of theoretical properties of plastics and processing applicable to a given problem. In the second part is designed double injection mold with hot runners. The following authentication function by analyzing the injection solution and the work concludes technical and economic assessment of the project.