Cette thèse décrit le design, la simulation et la fabrication d’une matrice 4x4 de micro-miroirs actionnée verticalement et munie d’un capteur de position. Le micro-scanneur vertical a pour vocation à être intégré au sein d’un micro-interféromètre de Mirau de type matriciel, réalisé àbase de composants micro-optiques fabriqués grâce à des méthodes collectives. Le mouvement du micro-scanneur, développé dans cette thèse, génère un signal de référence utilisé pour l’implémentation de l’interférométrie à modulation de phase dans un système de tomographie par cohérence optique (OCT). Dans un premier temps, la thèse introduit le besoin d’un système d’imagerie adapté pour la détection précoce des cancers de la peau et établit les spécifications optiques requises par cette application. A partir de ces spécifications, le design du système OCT basé sur le micro-interféromètre de Mirau est présenté. En parallèle, l’état de l’art des technologies de micro-actionnement est décrit et un actionnement électrostatique à base de peignes interdigités est choisi pour actionner et lire la position de la matrice de micro-miroirs. En effet ce type d’actionnement bénéficie d’une bonne compatibilité avec le design du micro-interféromètre de Mirau. Dans un second temps, le cœur de la thèse expose le développement du micro-scanneur vertical, c.à.d le design et les simulations ainsi que la fabrication et la caractérisation. / This thesis describes the design, simulation and fabrication of a vertically actuated 4x4 array ofmicromirrors with embedded position sensing function. The vertical microscanner is meant to beintegrated within an array-type Mirau microinterferometer realized with optical microcomponentsfabricated using collective techniques. The microscanner, developed in this thesis, provides areference signal that is used for the implementation of phase modulation interferometery in an opticalcoherence tomography (OCT) system. This thesis first introduces the need for adapted imagingsystems for the early diagnosis of skin cancer and establishes the optical specifications requiredby this specific application. Based on these specifications, the design of the OCT system based onthe Mirau microinterferometer is presented. In parallel, the state of the art of the microactuationtechnologies is discussed and comb drive electrostatic actuation is chosen, for its compatibilitywith the design of the Mirau microinterferometer, to actuate and sense the position of the array ofmicromirrors. Then, the core of the thesis deals with the development of the vertical microscanner,i.e. its design and simulations, its fabrication and its characterization.

This Research was undertaken to explore and better understand the perceptions of SMME owners, in South Africa, of the financial and non financial barriers and facilitators to the formalization/transitioning process. The study was motivated by the lack of data on the South African context of the barriers and facilitators of the formalization process. The conversion of enterprises from informal to formal concerns is not well researched and understood. In the absence of hard data, experienced observers and practitioners in the small business field express extreme skepticism about the efficacy of attempts to convert informal businesses to formal ones, (Bernstein, 2004). The research was conducted, mostly in Alexandra township Johannesburg, by means of 20 in-depth, semi-structured, face to face interviews with SMME owners; 10 operating informally and 10 who formally were, but have since transitioned/formalized. The resulting findings showed that lack of access to information on formalization and limited access to cash or credit are the major non financial and financial barriers respectively. Improved access to information on formalization is the major non financial facilitator and ability to access a bigger market plus increased access to cash or credit are the major financial facilitators. These findings also indicate that there may be a difference in the barriers and facilitators to formalization in South Africa as compared to what’s reported internationally in the literature. / Dissertation (MBA)--University of Pretoria, 2010. / Gordon Institute of Business Science (GIBS) / unrestricted

“Nanomaterials” is a generic term used to describe nano-sized crystals and bulk homogenous materials with a structural disorder at the nanoscale. Ancient (and modern) ceramics and glasses derive some of their properties (eg. pliability and low sintering temperature) from the fact that their raw material namely natural clay is nanosized. Furthermore the pigments used to colour ceramics and glasses need to have particle sizes <500 nm for the object to appear homogenously coloured to the human eye. Raman spectroscopy intrinsically probes chemical bonds and is therefore one of the few techniques that has been proven useful to provide information at the nanoscale. It is an excellent tool to study ceramics and glasses as a Raman spectrum can be used to identify phases, analyse amorphous domains in the silicate network and identify pigments on a nano-scale. The characteristics of a glass, ceramic or ceramic glaze derived through its Raman spectrum can then be linked to the technology used to produce an artefact and in this way provide information about its relative age and provenance. Likewise, the identification of pigments and binders in San rock art might provide information about production techniques and assist in the developement of conservation procedures. In this thesis micro-Raman spectroscopy (with X-ray fluorescence, X-ray powder diffraction, electronmicroscopy and photoluminescence as supportive techniques) was utilised to study archaeological artefacts from the Mapungubwe Collection and San rock art. It was possible to re-date celadon shards excavated on Mapungubwe hill in 1934 to the Yuan or even later Ming dynasty in stead of its original classification as Song. A profile of the glass technology used to produce the Mapungubwe oblates, small trade beads from the “royal burials” on Mapungubwe hill was determined and quite a few unique characteristics of the beads may eventually help to establish their provenance. The possible influence of the presence of rock hyraces at rock art sites on the deterioration of rock art were investigated and during the study very rare polymorphs of CaCO3 (vaterite and monohydrocalcite) were discovered in rock hyrax urine. This study was extended to analyse a San rock art fragment and another first was the identification of animal fat on the fragment, but the exact origin of the fat has to be verified by similar experiments. / Thesis (PhD)--University of Pretoria, 2009. / Physics / unrestricted

Le principal objectif de ce travail est l’investigation et la quantification de l’influence des interactions parent-macle et macle-macle sur la réponse mécanique des métaux hexagonaux, et en particulier sur celle du Mg et du Zr. Une nouvelle approche à champs moyens est tout d’abord proposée pour étudier l’interaction parent-macle. Cette dernière est déclinée en deux modèles micromécaniques à double-inclusion : un premier modèle généralisant le résultat de Tanaka-Mori aux milieux élastiques hétérogènes avec déformations libres de maclage appliqué au Mg pour du maclage primaire et secondaire, et un second modèle consistant en une extension du premier modèle à un milieu élasto-plastique appliqué à des polycristaux d’alliage de Mg subissant un maclage primaire important. Leurs résultats mettent notamment en valeur l’influence des interactions de type parent-macle sur l’évolution des contraintes internes ainsi que sur l’activation des modes de glissement et de maclage. L’influence des interactions macle-macle sur les phénomènes de nucléation et de croissance de macles est ensuite étudiée de façon statistique à partir de données EBSD extraites à partir d’un logiciel, basé sur la théorie des graphes et développé lors de la thèse. La première étude réalisée sur le Zr montre que les interactions macle-macle sont défavorables à la nucléation de nouvelles macles et que les mécanismes de croissance peuvent différer de façon conséquente d’un mode de maclage à l’autre. Une seconde étude, effectuée à partir d’échantillons d’alliage AZ31 Mg, discute des macles d’extension primaires {10-12} à faible facteur de Schmid et des double-macles {10-12}-{10-12} / The objective of this thesis is to investigate and quantify the influence of parent-twin and twin-twin interactions on the mechanical response of h.c.p. metals. To study parent-twin interactions, a mean-field continuum mechanics approach has been developed based on a double inclusion topology. A first model generalizing the Tanaka-Mori scheme to heterogeneous elastic media is applied to first and second generation twinning in Mg. The model is capable of reproducing the trends in the development of backstresses within the primary twin and enables the identification of the most likely second-generation twin variants to grow in a primary twin domain. A second self-consistent model, consisting of an extension of the first one to the case of elasto-plasticity, is applied to AZ31 Mg polycrystals. The results show that deformation system activities and plastic strain distributions within twins drastically depend on the interaction with parent domains. The influence of twin-twin interactions on nucleation and growth of twins is being statistically studied from Zr and Mg electron back-scattered diffraction (EBSD) scans. A twin recognition software relying on graph theory analysis has been developed for data extraction. The results obtained from Zr EBSD maps reveal that twin-twin interactions hinder subsequent twin nucleation and that mechanisms involved in twin growth may differ for each twinning mode. A second study performed on AZ31 Mg presents statistics about low Schmid factor {10-12} tensile twins and about {10-12}-{10-12} double twins coupled with a simplified version of the Tanaka-Mori scheme generalized to heterogeneous elasticity with plastic incompatibilities.

The active state of plasminogen activator inhibitor type-1 (PAI-1) is prolonged when it forms a complex with vitronectin (VN), a major serum protein. Active PAI-1 in the PAI-1:VN complex serves many functions related to fibrinolysis and cell migration but key to these effects is its extracellular distribution. PAI-1:VN complexes can bind to exposed vimentin (VIM) on activated platelet and platelet microparticles, resulting in the assembly of PAI-1:VN:VIM ternary complexes. However, the manner in which the vimentin cytoskeleton is presented extracellularlyi s not well understood. I hypothesized that PAI-1:VN:VIM ternary complex assembly occurs on cell surfaces when microparticle release leads to exposure of vimentin cytoskeleton which can lead to either assembly of the ternary complex or become involved in an autoimmune response specific for vimentin. To follow the intracellular and extracellular fate of PAI-1, I constructed an expression vector encoding PAI-1-dsRed, a fluorescent form of PAI-1, which would permit live cell tracking of PAI-1 in megakaryocytes and endothelial cells. Secondly, to study how vimentin is expressed on platelets and platelet microparticles, flow cytometry was used to isolate vimentin positive platelets or PMP's and atomic force microscopy was performed to image platelets or PMP's at nanoscale resolution. From these studies, I propose a model of vimentin expression in which the junction of microparticle release results in the exposure of cytoskeletal vimentin on both the cell and the microparticle. This exposed vimentin could potentially induce VN multimerization on the same cell surface leading to incorporation of multiple PAI-1:VN complexes. Finally, I investigated how anti-vimentin antibodies can induce platelet:leukocyte conjugate formation. To achieve this, in vitro tests were performed to determine the binding site of anti-vimentin antibodies (AVA's) and how they induce blood cell activation. Overall, my results suggest that vimentin exposure in our model of microparticle release can lead to ternary complex assembly if suitable quantities of PAI-1 are released during platelet activation. In the setting of transplant vasculopathy with high titres of AVA's, vimentin-positive granulocytes can bind these autoantibodies, which then leads to platelet activation and the formation of platelet:leukocyte conjugates. / Medicine, Faculty of / Pathology and Laboratory Medicine, Department of / Graduate

Microfluidics refers to devices and methods for controlling and manipulating fluid flows at length scales less than a millimeter. Miniaturization of a laboratory to a small device, usually termed as lab-on-a-chip, is an advanced technology that integrates a microfluidic system including channels, mixers, reservoirs, pumps and valves on a micro scale chip and can manipulate very small sample volumes of fluids. While several flow control concepts for microfluidic devices have been developed to date, here flow control concepts based on thermally responsive polymer solutions are presented. In particular, flow control concepts base on the thermally triggered reversible phase change of aqueous solutions of the polymer Pluronic will be discussed. Selective heating of small regions of microfluidic channels, which leads to localized gel formation in these channels and reversible channel blockage, will be used to control a membrane valve that controls flow in a separate channel. This new technology will allow generating inexpensive portable bioanalysis tools where microvalve actuation occurs simply through heaters at a constant pressure source without a need for large external pressure control systems as is currently the case. Furthermore, a concept for controlled cross-channel transport of particles and potentially cells is presented that relies on the continuous regeneration of a gel wall at the diffusive interface of two co-streaming fluids in a microfluidic channel. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

Les travaux de thèse concernent le design optique et le développement d’un microscope confocal miniature MEMS intégré verticalement. Différentes architectures optiques ont été proposées afin de combiner un design optique optimal aux nombreuses contraintes technologiques liées à la fabrication collective des différents blocs élémentaires du microscope sur puce. Ceux-ci, réalisés avec des technologies hybrides, sont encapsulés par assemblage vertical de wafers utilisant les technologies de soudure ≪multi-wafer≫, et permettent la construction d’un microsystème complet d’instrumentation. Un accent particulier a été émis sur la minimisation des aberrations optiques générées par les différents composants micro optiques pour permettre une résolution de mesure élevée. Pour satisfaire ces besoins, différentes briques élémentaires ont été développées : un cube semi-transparent micro-fabriqué, différentes microlentilles réfractives basées sur le micro moulage silicium et un micro-objectif réflecteur. Un montage expérimental de caractérisation dédié à l’ évaluation de la qualité de ces micro composants a également été proposé. De plus, les différents procédés de micro-usinage silicium (gravure humide anisotrope et isotrope, gravure sèche isotrope du silicium) pour la génération de micro-miroirs et de microlentilles ont été comparés. Enfin, les procédures d’assemblage vertical, incluant toutes les technologies d’interconnexion électrique ont été développées. Le travail de thèse a été réalisée dans le cadre du projet DWST-DIS ( The Development of Multi Wafer Stacking 3D Technology for Displays and Imaging MicroSystems), programme financé par le programme Inter Carnot Fraunhofer (PICF) - un projet ANR entre FEMTO-STet l’institut Fraunhofer ENAS. / The thesis manuscript concerns optical design and development of a vertically integrated MEMSbasedconfocal microscope. Different optical architectures have been proposed that aim to combineoptimal optical design and the numerous technological constraints linked to the batch fabricationof the different building blocks. The latter, made by hybrid technologies, and packaged byvertical assembly using multi- wafer bonding, allow the construction of a complete microsystem forinstrumentation. Special emphasis is placed on the minimization of optical aberrations generatedby the different microoptical components to ensure good resolution of measurement. For thesepurposes, different building blocks have been developed, namely a batch-fabricated cube-typedbeamsplitter, different silicon moulded refractive microlenses and a miniature reflective objective.Dedicated characterization system for quality assessment of the fabricated micro-components wasalso developed. Moreover, different processes of silicon-based micromachining for generation ofmicromirrors and microlenses (wet anisotropic and isotropic etch, dry isotropic etch of silicon) havebeen compared. Finally, procedures of vertical assembly including all electrical interconnectiontechnologies have been developed. The thesis work was performed in the frame of the DWST-DIS(The Development of Multi Wafer Stacking 3D Technology for Displays and Imaging MicroSystems)project funded by the Programme Inter Carnot Fraunhofer (PICF) – an ANR project between FEMTO-STand ENAS - Fraunhofer Institute.

Cette thèse traite un sujet pluridisciplinaire, la conception d’un prototype de micro-capteur biologique pour la détection des anticorps de patients susceptibles d'être allergiques.Elle a pour objectif la miniaturisation de la méthode ELISA pour « Enzyme Linked Immune Sorbent Assay » en concevant en « full-custom », avec une technologie CMOS APS, un capteur colorimétrique. Ce capteur est posé en dessous un système micro fluidique contenant l’échantillon biologique à tester, le tout est illuminé via une fibre optique. Le détecteur capte la lumière qui a traversé le micro-tube contenant l’échantillon. Les courants photoniques induits sont liés à la concentration et la coloration de la solution. Le virage colorimétrique de la réaction enzymatique, due à la présence des anticorps dans le sérum, et l’évaluation quantitative de la concentration seront déterminée par la mesure de ces photo-courants. Le capteur pourrait contenir une matrice de 20x20 pixels de détecteurs de couleur ainsi que leur électronique de lecture et de commande. Pour des raisons de coûts, nous avons validé le procédé à l’aide d’une matrice de 4x4 pixels de détecteur de couleur. La réalisation du circuit a été suivie par une caractérisation électrique et colorimétrique. La caractérisation électrique a permis de valider le fonctionnement du bloc de commande du circuit ainsi que celui du pixel (l’électronique de lecture, BDJ). Les résultats de mesures concordent avec ceux de simulations. La caractérisation colorimétrique consiste à mesurer le virage colorimétrique de deux solutions différentes. Les mesures ont pu montrer que notre capteur est plus sensible que le spectromètre utilisé pour mesurer la concentration des deux solutions. Ainsi ce travail de recherche a contribué à la miniaturisation d’une bio-puce colorimétrique dédiée aux tests immunologiques basée sur la méthode ELISA. / This PhD treats a multidisciplinary subject based on the design of a biological micro-sensor prototype for the detection of antibodies of patients susceptible to be allergic.The goal has been the miniaturization of the ELISA "Enzyme Linked Immune Sorbent Assay" method, designing in integrated full-custom colorimetric sensor with a CMOS APS technology. This sensor is installed below a microfluidic system containing the biological test sample, the whole is illuminated via an optical fiber. The sensor detects the light passed through the micro reservoir containing the sample, the induced photo-currents is related to the concentration of the solution. The color change of the enzyme reaction due to the presence of antibodies in the serum, and the quantitative evaluation of the concentration will be determined by the measurement of the induced photo-currents. The sensor may contain a matrix of 20x20 color detector pixels and their reading and control electronics. For cost reasons, we validated the method using a matrix of 4 x 4 pixels of color detectors.The design of electrical device was followed by a colorimetric and electrical characterizations. The latter was used to validate the operation of the control block of the circuit as well as that of the pixel (readout electronics, BDJ). The results brought by measurements are in good agreement with those obtained through simulations. The colorimetric characterization consists in measuring the intensity of the color of two different solutions of different colors. These measurements have shown that our sensor is more sensitive than a spectrometer. Therefore, this research work has contributed to the miniaturization of a colorimetric sensor and its electronic part for the Immunoassay based on the ELISA method.

Businesses cluster to achieve agglomeration benefits. However, research in developing countries suggests that the economic environment limits small business’ propensity to benefit from agglomerations. The study examines the location, networking patterns, formal structures and owner characteristics of 1256 micro businesses from ten industries and thirteen sample areas in Toluca, Mexico. First, the thesis analyses whether clustering has a positive impact on the success rates of the surveyed enterprises, e.g. higher sales per employee. On an industry scale only Retail benefits from agglomerations economies. However, results of the neighborhood data show that specific areas benefit from urbanization economies. Overall, the study finds that businesses located within agglomerations, have higher levels of formalization, networking and professional training, hence constituting a more sophisticated base for economic development. Conclusions can be drawn for development policies and programs, arguing for a more differentiated approach of small business development depending on business location and cluster characteristics.

Orientador: Marcelo Ferraz Mesquita / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-03T16:12:10Z (GMT). No. of bitstreams: 1 Almeida_MarcoAntonioBorgesde_D.pdf: 3316387 bytes, checksum: 4a317591e4fe3a13b286e2e0eac92827 (MD5) Previous issue date: 2003 / Resumo: o objetivo deste estudo foi verificar a movimentação linear dos dentes em prótese total superior, confeccionada com resina acrílica ativada termicamente, processada pela técnica de caracterização intrínseca, sob a influência de dois métodos de polimerização: água aquecida e energia de microondas. A partir da duplicação de uma prótese total superior confeccionou-se 30 conjuntos idênticos de modelo de gessolbase-de-provaldentes artificiais. Estes conjuntos foram separados aleatoriamente em três grupos experimentais, sendo submetidos aos seguintes tratamentos: G1- processamento de caracterização intrínseca com polimerização em microondas; G2- processamento convencional com polimerização em água aqueci da (controle); G3- processamento de caracterização intrínseca com polimerização em água aquecida. A movimentação linear dos dentes foi mensurada em sete distâncias em cada prótese, em dois estágios de sua confecção: antes da inclusão e após polimerização, acabamento, polimento e armazenagem em água destilada à temperatura de 37°C :t 2°C por 30 dias. Todas as mensuraçóes foram realizadas por um mesmo operador em microscópio comparador linear (Olympus), com precisão de 0,0005mm. Os dados obtidos e submetidos ao teste de Kruskal-Wallis em nível de 5% de significância permitiram concluir que: A movimentação linear dos dentes artificiais, nos grupos processados pela técnica de caracterização intrínseca em ambos os métodos de polimerização investigados, não apresentou diferença estatística significativa para a maioria das distâncias avaliadas; A escolha da técnica de processamento a ser empregada deve ser baseada em critérios individuais e particulares que considerem o domínio da técnica de processamento empregada, o tempo de confecção despedido e o resultado estético a ser alcançado; A correta execução dos procedimentos técnicos e laboratoriais durante as etapas de confecção das próteses totais deve prevalecer à escolha deste ou daquele ciclo de polimerização, técnica de processamento ou marca comercial de resina / Abstract: The aim of this study was to verify the linear teeth movement in maxillary denture made with heat-cured acrylic resin, processed by technique of intrinsic characterization, under influence of two methods of polymerization heat-water and microwave energy. Thirty identical maxillary dentures were obtained and randomly assigned in 3 groups in order to receive the following treatments: Group 1- intrinsic characterization processing and microwave polymerization; Group 2- conventional processing and heat-water polymerization; Group 3- intrinsic characterization processing and heat-water polymerization. Seven individual measurements were taken on each denture at two specific stages in the construction of denture: before investment and after polymerization, finishing, polishing procedures and storage in the water at 37°C :f: 2°C for 30 days. Measurements were made by a single operator with a linear comparator microscope (Olympus), with accuracy of 0,OOO5mm. Data were analyzed with Kruskal-Wallis test at 5% of significance and showed that: The linear movement of artificial teeth, in the groups processed for the technique of intrinsic characterization in both the investigated methods of polymerization, was without difference significant statistics for the majority of the evaluated distances; The choice of the technique of processing must be based on individual and particular criteria that consider the domain of the processing technique used, the time consumed and the aesthetic result to be reached; The correct execution of the technical procedures and laboratorial stages of construction of the dentures must prevail to the choice of this or that cycle of polymerization, technique of processing or commercial resin brand / Doutorado / Protese Dental / Doutor em Clínica Odontológica