Made available in DSpace on 2014-10-09T12:26:04Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:20Z (GMT). No. of bitstreams: 1 11269.pdf: 1856747 bytes, checksum: b76814c0b5cd3ff897d8e9bb0f9b3990 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:26:04Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:10:20Z (GMT). No. of bitstreams: 1 11269.pdf: 1856747 bytes, checksum: b76814c0b5cd3ff897d8e9bb0f9b3990 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Philosophiae Doctor - PhD / Microbial nitrile hydratases (NHases) are important industrial enzymes that catalyse the conversion of nitriles to the corresponding amides. A thermostable, cobalt-type Bacillus sp. RAPc8 NHase was previously cloned and expressed in E. coli. In this study, the primary aim was to determine the molecular structure of Bacillus sp. RAPc8 NHase. The heterotetrameric enzyme was purified to near homogeneity using heatpurification, hydrophobic interaction chromatography and ion exchange chromatography. Purified NHase was crystallised using the hanging-drop vapourdiffusion method. Crystals produced in the presence of 30% PEG 400, 0.1M MES pH 6.5 and 0.1M magnesium chloride were selected for X-ray diffraction studies. These crystals diffracted well, with diffraction spots visible beyond 2.4Å, with little mosaicity. At 2.5Å, the data were 93% complete. The crystal structure of Bacillus sp. RAPc8 NHase was solved via molecular replacement using the crystal structure of Pseudonocardia thermophila NHase as a search model. The final refined structure had good refinement statistics and geometry. The overall fold was very similar to that of previously determined NHase structures. Bacillus sp. RAPc8 NHase was most similar to Bacillus smithii NHase (0.355År.m.s.d.) and least similar to Rhodococcus sp. R312 NHase (1.191Å r.m.s.d.). One cobalt atom per heterodimer was bound to a typical NHase metal-binding motif, with post-translationally modified cysteine residues among the ligands to the metal. The substrate-binding and catalytic cavity of Bacillus sp. RAPc8 NHase was identified and described in detail. Surface representation of the structure revealed an extended, curved solvent accessible channel with access to bulk solvent from two locations in the heterodimer. The amino-acid residues forming the channel were identified and the geometric dimensions measured. Enzyme inhibition kinetics indicated that benzonitrile was a potent uncompetitive inhibitor of NHase. This information was used to aid the genetic engineering of aromatic substrate specificity into Bacillus sp. RAPc8 NHase. Site-directed mutants of NHase were prepared using the Quickchange mutagenesis procedure. Mutant W76G showed a two to three fold decrease in benzonitrile inhibition compared with the wild-type. Analysis of the substrate channel of this mutant NHase showed an 11% increase in volume and a 20% increase in inner surface area compared to that of the wild-type NHase. Due to the lack of other significant differences between the two structures (an r.m.s.d. of only 0.101Å was observed), this difference was thought to be responsible for the decrease in benzonitrile inhibition. A structure-modelling based approach for assessing the likely structural differences that may result as a result of a specific mutation was suggested and tested. This approach may be of value in future mutagenesis work. / South Africa

The research investigated the application of continuous coaxial laser cladding by powder injection as a surface treatment or coating process. The investigation aimed to establish the relationship between a change in the main laser cladding process variables and the geometry and characteristics of an Al-20wt-Si single pass clad layer formed on an Al 1370-F substrate using a Nd:YAG laser. The main process variables considered were: laser power, laser scanning velocity and the powder feed rate. The relationship between a change in the main laser cladding process variables and the geometry and characteristics of the clad layer was established by statistically analysing the variation in the process response with a change in the main laser cladding process variables. The process variables were varied based on a full-factorial, experimentally optimized test matrix. The clad geometry which is mainly defined by: the clad height, width, clad aspect ratio, depth of alloy penetration, and the clad root angle/wetting angle was investigated. In addition to the clad geometry several clad characteristics were investigated such as the dilution of the clad layer in the substrate material, the Vickers microhardness and microstructure of the clad crosssection, the powder efficiency of the process and the amount of visible defects. The study successfully established the relationship between the main laser cladding process variables and the clad geometry and characteristics. The secondary objective of establishing a suitable processing window by considering the relationship mentioned above was only partially met since it is believed that further refinement of the experimental cladding test setup and therefore also the experimental variable test levels is required.

This thesis is a study of the interference forces acting on one cylinder comprising a group of three and four cylinders when situated in a free stream flow. The spacing of the cylinders was such that the lines joining their axes formed an equilateral triangle, and a square respectively. The study is split into two parts, (a) potential flow over the groups of cylinders (b) real flow over the groups of cylinders. Bound with copies of the authors' published papers.~Bibliography: pages 132-137.

Today, thin client applications often rely on the infrastructure of the WWW to deliver their user interfaces (UIs) to clients. While this approach does not require the deployment of application logic on the client, web-based UIs typically do not provide the same level of usability as window-based UIs. We therefore present a UI framework that combines the flexibility of a thin presentation logic with the usability of a full-featured UI: Our approach uses an XMPP-based instant messaging infrastructure to exchange XUL interface descriptions and events between the application logic on the server and a generic UI rendering engine on the client.

El presente trabajo de tesis desarrolla el diseño de una plataforma de virtualización de aplicaciones que pueda atender usuarios locales, externos y móviles de una organización. Esta plataforma de virtualización será diseñada bajo el modelo de disposición en capas y siguiendo los estándares, recomendaciones y buenas prácticas de cada uno de los fabricantes que componen la solución, así como también de metodologías de trabajo como la Gestión de puntos finales unificados (UEM- Unified endpoint management). En el primer capítulo del presente diseño, hablaremos a grandes rasgos de la organización objetivo en el cual se desea plasmar dicho proyecto, así como la situación problemática en el campo de acción de la organización, luego definiremos el objetivo general y sus respectivos objetivos específicos e indicadores. En el segundo capítulo, se presentará el marco teórico, el cual incluirá toda la información referente a las definiciones, normativa y metodología a utilizar. En el tercer capítulo, se realizará el análisis del problema a solucionar con el diseño a proponer, además se identificarán los problemas con la información recabada de la organización, con ello se elaborará el análisis del alcance, impacto y soluciones posibles. En el cuarto capítulo, se mencionan a detalle las especificaciones del diseño multicapas de la plataforma de virtualización de aplicaciones. Y finalmente, se mostrarán los resultados y validaciones, los cuales servirán para demostrar el cumplimiento de los objetivos específicos planteados en el capítulo uno. / This thesis work develops the design of an application virtualization platform that can serve local, external and mobile users of an organization. This virtualization platform will be designed under the layered layout model and following the standards, recommendations and good practices of each of the manufacturers that make up the solution, as well as work methodologies such as EMM (EMM - Enterprise Mobility Management) . In the first chapter of the present design, we will speak in broad strokes of the objective organization in which it is desired to capture said project, as well as the problematic situation in the field of action of the organization, then we will define the general objective and its respective specific objectives and indicators. In the second chapter, the theoretical framework will be presented, which will include all the information regarding the definitions, regulations and methodology to be used. In the third chapter, the analysis of the problem to be solved with the design to be proposed will be carried out, in addition the problems will be identified with the information collected from the organization, with this the analysis of the scope, impact and possible solutions will be elaborated. In the fourth chapter, the multilayer design specifications of the application virtualization platform will be mentioned in detail. And finally, the results will be displayed and validations, which will serve to demonstrate compliance with the objectives specific ones raised in chapter one. / Tesis

<p>    </p> <p>Machine learning (ML) models can help improve health care services. However, they need to be practical to gain wide adoption. A methodology is proposed in this study to evaluate the utility of different data modalities and cohort segmentation strategies when designing these models. The methodology is used to compare models that predict emergency department (ED) and inpatient hospital (IH) visits. The data modalities include socio-demographics, diagnosis and medications and cohort segmentation is based on age group and disease severity. The proposed methodology is applied to models developed using a cohort of insomnia patients and a cohort of general non- insomnia patients under different data modalities and segmentation strategies. All models are evaluated using the traditional intra-cohort testing. In addition, to establish the need for disease- specific segmentation, transfer testing is recommended where the same insomnia test patients used for intra-cohort testing are submitted to the general-patient model. The results indicate that using both diagnosis and medications as a source of data does not generally improve model performance and may increase its overhead. For insomnia patients, the best ED and IH models using both data modalities or either one of the modalities achieved an area under the receiver operating curve (AUC) of 0.71 and 78, respectively. Our results also show that an insomnia-specific model is not necessary when predicting future ED visits but may have merit when predicting IH visits. As such, we recommend the evaluation of disease-specific models using transfer testing. Based on these initial findings, a language model was pretrained using diagnosis codes. This model can be used for the prediction of future ED and IH visits for insomnia and non-insomnia patients. </p>

Web applications are quickly replacing standalone applications for everyday tasks. These web applications need to be tested to ensure proper functionality and reliability. There have been substantial efforts to create tools that assist with the testing of web applications, but there is no standard set of tools or a recommended workflow to ensure speed of development and strength of application. We have used and outlined the merits of a number of existing testing tools and brought together the best among them to create what we believe is a fully- featured, easy to use, testing framework and workflow for web application devel- opment. We then took an existing web application, PolyXpress, and augmented its development process to include our workflow suggestions in order to incorporate testing at all levels. PolyXpress is a web application that “allows you to create location-based stories, build eTours, or create restaurant guides. It is the tool that will bring people to locations in order to entertain, educate, or provide amazing deals.”[10] After incorporating our testing procedures, we immediately detected previously unknown bugs in the software. In addition, there is now a workflow in place for future developers to use which will expedite their testing and development.

In information systems design there are two schools of thought about what factors are necessary to create a successful information system. The first, conventional view holds that system performance is a key, so that efficiency characteristics such as system usability and task completion time are primary concerns of system designers. The second, emerging view holds that the visual design is also the key, so that visual interface characteristics such as visual appeal, in addition to efficiency characteristics, are critical concerns of designers. This view contends that visual design enhances system use. Thus, this work examines the effects of visual design on computer systems. Visual design exerts its influence on systems through two mechanisms: it evokes affective responses from IT users, such as arousal and pleasure and it influences individuals’ cognitive assessments of systems. Given that both affective and cognitive reactions are significant antecedents of user behaviors in the IT realm, it is no surprise that visual design plays a critical role in information system success. Human-computer-interaction literature indicates that visual aesthetics positively influences such information success factors as usability, online trust, user satisfaction, flow experience, and so on. Although academic research has introduced visual design into the Information Systems (IS) field and validated its effects, visual design is still very limited in three contexts: product aesthetics in e-commerce, mobile applications and commercial emails. This dissertation presents three studies to help fill these theoretical gaps respectively.