No description available.

The structural evolution of the Ox Mountains Granodiorite (478±12Ma) during and after its emplacement is described. This pluton has been emplaced within and synchronously with, a major transpressional shear zone which is expressed as a 11km wide belt of strongly deformed NE-SW striking, steeply dipping metasediments. The steep shear zone cleavage is intensified to a mylonitic fabric in a braided system of high strain zones formed through out the Ox Mountains Inlier. Pervasive ductile, sinistral deformation in the shear zone is interupted by the emplacement of the pluton and by the synchronous development in the country rocks of series of brittle thrust structures, which produced a displacement upwards and towards the centre of the shear zone. These thrusts are intimately associated with the emplacement of moderately inclined granodiorite sheets belonging to the main intrusive phase indicating a component of vertical extension in the country rocks at this time. The CMC is a heterogeneous, four component pluton internally composed of a series of large sheets or dykes. Minor muscovite granite sheets emplaced along the northern contacts, preceeded the main intrusive sheets of Group 1 and Group 2 granodiorite with associated diorites. Sheets of tonalites and minor components completed the emplacement history. A prolonged history of sinistral transpressional shearing has deformed the pluton. Discrete sinistral shears indicate an early localization event is overprinted by a main ductile penetrative fabric which cross-cuts ail internal contacts. This fouation is deformed by extensive sinistral S-C fabrics. Later deformation becomes increasingly partitioned into late sinistral and dextral shear zones which are locally mylonitic. Microstructural evidence suggests that the main foliation was formed under lower amphibolite facies and deformed by a steady state flow process. The S-C fabric and late shear zone formation, best developed in the granodiorites and granites, may have been initiated by a switch in the predominant alkalifeldspar deformation mechanism from crystal plastic to a diifusive mass transfer process. This may be a retrogessive effect, and the product is a grain size reduction which may lead to ultramylonite production. The emplacement model for the Ox Mountains Granodiorite is constrained by the original geometry of the dykes or sheets. These data rule out emplacement of the OMG in a releasing bend or pull-apart structure. Strain data does not allow a forceful mechanism and a permissive emplacement model is preferred, in which vertical extension during the intrusive episode created an area of dilation in which dyking occurred. This was caused by oblique movements on two upwardly converging high strain zones outside the pluton. Two satellite plutons, the Lough Talt Adamelhte and the Easkey Lough Adamellite were emplaced in extensional cavities created by reactivated sinistral movements on one of the high strain zones at a much later date. (c400Ma).Transpressional shear zones may initiate or enhance melting in the lower crust and mantle lithosphere where thermal perturbation has occurred. The shear zones may provide conduits for the melts and emplacement sites, especially where high transpressional strains are accommodated by vertical uplift.

Magister Artium - MA / This thesis is concerned with the lives and deaths of four 1938 Voortrekker Centenary Monuments. The 1938 Voortrekker Centenary saw the construction of more than 500 centenary monuments. Each one of these structures has a biography. This study will consider how monuments celebrate current regimes and ideologies instead of narratives pertaining to the past. It will explore how monuments dating from South Africa’s imperialist and apartheid pasts reflect continued inequalities in both rural and urban South African landscapes. It will also consider how monuments cement problematic and mythological versions of the past. The most infamous 1938 Voortrekker Centenary Monument is the Voortrekker Monument, designed by Gerard Moerdyk, in Pretoria. The Voortrekker Monument is important because in many ways it acts as a proxy to the hundreds of smaller 1938 Voortrekker Centenary Monuments scattered around South Africa. This study will look at how some of the theoretical frameworks concerned with the Voortrekker Monument in Pretoria can be applied to three centenary monuments in the Riebeek Valley and Durbanville in the Western Cape. This thesis will consider how perceptions of the symbolism of these monuments have changed between their construction in the late 1930s and 2018. The Afrikaner nationalistic fever that gave birth to these structures will be dissected. It will also consider how the 1938 Voortrekker Centenary Monuments symbolically changed as South Africans witnessed the disintegration of apartheid. This study will explore how these monuments have integrated into the heritage and experiential economies. It will also consider some of the anomalies relating to these structures, including hauntings. Finally, the vandalism, destruction and futures of these structures will also briefly come into question.

No description available.

Sabemos da literatura que Calibração Comparativa está ligada à comparação de eficiência de instrumentos de medição. Neste trabalho discutimos estimação e testes de hipóteses em modelos de calibração comparativa. Para a estimação dos parâmetros do modelo, consideramos os algoritmos EM e o algoritmo BFGS do programa Ox. Testes para algumas hipóteses de interesse são implementados usando as estatísticas da razão de verossimilhanças e de Wald. Estudos de simulação são utilizados na comparação dos procedimentos. Uma aplicação é apresentada a um conjunto de dados constituído de medições de alturas de árvores com três, quatro e cinco hipsômetros. / We know about the literature that Comparative Calibration it is linked the efficiency comparison of measurement instruments. In this work we discuss estimates and tests of hypotheses in comparative calibration models. For the estimate of the parameters of the model, we consider the EM algorithm and the algorithm BFGS in the program Ox. Testings for some hypotheses of interest are implemented using the likelihood ratio and Wald statistics. Simulation studies are used in the comparison of the procedures. An application is presented to a data set, constituted of measurements of heights of trees with three, four and five hipsometers.

Sabemos da literatura que Calibração Comparativa está ligada à comparação de eficiência de instrumentos de medição. Neste trabalho discutimos estimação e testes de hipóteses em modelos de calibração comparativa. Para a estimação dos parâmetros do modelo, consideramos os algoritmos EM e o algoritmo BFGS do programa Ox. Testes para algumas hipóteses de interesse são implementados usando as estatísticas da razão de verossimilhanças e de Wald. Estudos de simulação são utilizados na comparação dos procedimentos. Uma aplicação é apresentada a um conjunto de dados constituído de medições de alturas de árvores com três, quatro e cinco hipsômetros. / We know about the literature that Comparative Calibration it is linked the efficiency comparison of measurement instruments. In this work we discuss estimates and tests of hypotheses in comparative calibration models. For the estimate of the parameters of the model, we consider the EM algorithm and the algorithm BFGS in the program Ox. Testings for some hypotheses of interest are implemented using the likelihood ratio and Wald statistics. Simulation studies are used in the comparison of the procedures. An application is presented to a data set, constituted of measurements of heights of trees with three, four and five hipsometers.

Este projeto teve como objetivo geral continuar a avaliar a adequação de anfifílicos que se agregam em solução aquosa formando bicamadas, para recobrir superfícies de sílica. Em paralelo, foi objetivada a reconstituição do reconhecimento receptor-ligante, tendo como modelo o monosialogangliosídio GM1 e a enterotoxina do vibrião da cólera. Os resultados obtidos poderão se mostrar de grande valor em aplicações práticas que envolvem a construção de sistemas de detecção e quantificação de substâncias ou moléculas específicas. A adsorção e estabilidade de bicamadas contendo fosfatidilcolina (PC) ou misturas de brometo de dioctadecildimetilamônio (DODAB) e dipalmitoilfosfatidilcolna (DPPC) sobre a superfície de nanopartículas de sílica foi estudada através de isotermas de adsorção por dosagem do fosfato inorgânico, análises de sedimentação por imagens fotográficas e medidas dos diâmetros médios (Dz) e potenciais-zeta (ζ) de partículas por espectroscopia de correlação de fótons. Foram avaliadas as afinidades entre as bicamadas e a superfície das nanopartículas e a estabilidade do sistema em função da força iônica, do pH e da concentração adicionada de lipídio. A afinidade das bicamadas pela superfície da sílica apresentou uma correlação com as forças de van der Waals e as pontes de hidrogênio que se formam entre os grupos químicos do anfifílico e aqueles de superfície da sílica. A formação de uma única bicamada lipídica de PC sobre a sílica foi detectada, o que levou à estabilidade coloidal do sistema particulado. As bicamadas mistas de DPPC/DODAB por sua vez apresentaram uma afinidade decrescente pela sílica com a elevação da porcentagem de DODAB na bicamada. Os dados de isoterma e de ζ das partículas sugerem uma separação física entre o DPPC e o DODAB. O conjunto otimizado partícula de sílica/bicamada de PC (partícula biomimética) foi assim utilizado para promover a incorporação do GM1 micelar nas bicamadas, medida por fluorescência com a utilização da sonda GM1 pireno, seguida do reconhecimento e ligação da toxina da cólera (CT) ao complexo formado. A transferência do GM1 das micelas para as partículas se mostrou dependente da disponibilidade de bicamadas adsorvidas nestas e da ausência de bicamadas não-adsorvidas, livres em dispersão. Para avaliar a ligação da toxina da cólera às partículas biomiméticas foram calculadas isotermas de adsorção a partir da dosagem de proteína não ligada que resta no sobrenadante. A ligação específica da CT na presença de bicamadas de PC e GM1 foi de 67% em massa do total da proteína adicionada, revelando uma ligação positiva entre receptor e ligante. A estequiometria revela que a proporção molar PC: GM1: CT é de 300: 5: 1 respectivamente. A proporção de 1 CT: 5 GM1 está de acordo com a literatura onde experimentos de difração de raios-X mostram a estrutura tridimensional do pentâmero CTB5 ligado a cinco unidades de pentasacarídeo do GM1. / The general objective of this project was to continue evaluating the suitability of amphiphiles that aggregate in aqueous solution forming bilayers, to cover surfaces of silica. A secondary objective pursued was to promote the reconstitution of the receptor-ligand function, having as a model the monosialoganglioside GM1 and the enterotoxin of the choleric vibrio. The results may prove to be valuable in pure research or practical applications for sensing and detection of biomolecules. The adsorption and stability of phosphatidylcholine (PC) bilayers or mixtures of dipalmitoylphosphatidylcholine (DPPC) and dioctadecyldimethylammonium bromide (DODAB) over surfaces of silica nanoparticles were evaluated through adsorption isotherms by inorganic phosphate dosage, sedimentation analysis by means of photographic images and measurements of hydrodynamic diameter (Dz) and zeta-potentials (ζ) of particles by photon correlation spectroscopy. The affinity between the bilayers and the nanoparticles surfaces and the general system stability were evaluated as a function of ionic strength, pH and added lipid concentration. The affinity showed a correlation with the van der Waals and the hydrogen bridges forces that form between the chemical groups of the amphiphile and the silica surface. The formation of a single lipid PC bilayer over the silica was detected, leading to the colloidal stability of the particulate system. Mixed bilayers of DPPC/DODAB on the other hand showed a decreasing affinity for silica with an increasing DODAB percentage in the bilayer. Data from isotherms and ζ of particles suggests a physical separation of the DPPC and DODAB. The optimized array of silica particle/PC bilayer (biomimetic particles) was thus used to promote the incorporation of micellar GM1 into the bilayers, measured by fluorescence with a GM1 pirene probe, followed by the cholera toxin (CT) binding to the resulting array. GM1 transfer from micelles to particles showed dependence on the adsorbed bilayers availability and on the absence of non-adsorbed bilayers, free in the bulk solution. To evaluate CT binding to biomimetic particles adsorption isotherms were calculated from the dosage of unbound protein remaining in the supernatant. Specific binding of CT in the presence of PC and GM1 bilayer was 67% mass of total protein added, indicating a positive binding between receptor and ligand. Stoichiometry revealed that the molar proportion PC: GM1: CT is 300: 5: 1 respectively. The proportion of 1 CT: 5 GM1 is in good agreement with data in the literature where X-ray diffraction tests show the 3-dimensional structure of the CTB5 pentamer bound to five units of the pentasaccharide GM1.

La connaissance des interactions interfaciales et l'énergie de surface est nécessaire pour étudier et modéliser les processus qui se déroulent dans le mouillage, l'adhésion ou la diffusion. Tels phénomènes sont rencontrés dans la préparation des suspensions, des émulsions et les peintures. Dans ce contexte, l'énergie de surface représente un paramètre important dans l'étude des propriétés interfaciales solide/liquide où plusieurs applications sont impliquées. Nous avons étudié l'effet de la modification chimique sur l'énergie de surface de deux silices choisies selon deux différentes échelles: l'OX qui présente un substrat nanométrique et les wafers de silicium qui est un substrat millimétrique. Pour la silice OX 50, La modification chimique de la surface a été réalisée avec l'hexadecyltrichlosilane (HTS) à caractère hydrophobe. L'infrarouge en transmission et la quantification de carbone organique ont été efficaces pour estimer les quantités croissantes d'HTS greffées à la surface de la silice. Deux isothermes d'adsorption ont été tracées. Ensuite, la volumétrie d'adsorption continue d'argon et d'azote a été utilisée pour étudier l'évolution de l'hétérogénéité énergétique. Ceci a été achevé en faisant recours à une stratégie d'analyse de volume adsorbée à la monocouche (Vm) d'azote et d'argon. Les résultats obtenus ont servi pour tracer une troisième isotherme d'adsorption. La quantification de l'énergie de surface a été réalisée avec la montée capillaire (technique macroscopique) et la chromatographie gazeuse en phase inverse (CGI) (technique moléculaire). Pour les wafers de silicium, deux types de surfaces ont été élaborées durant cette étude. Le premier hydrophile (traitement Piranha, formations des groupements OH). Cette surface a été obtenue par oxydation de ces wafers (traitement Piranha). La deuxième a été obtenue par le greffage d'HTS (greffons CH3). La quantification de l'énergie de surface a été réalisée avec la mouillabilité (technique macroscopique) et la microscopie à force atomique (AFM) (technique nanoscopique). Enfin, les différentes valeurs d?énergie de surface de la silice vierge OX 50 ont été comparées avec celles de la surface plane hydrophile (OH). Pour les surfaces hydrophobes, on a comparé les valeurs d?énergie de surface de la silice OX 50 modifiée d'une quantité maximale d?HTS avec le wafer de silicium à greffons CH3 / The knowledge about interfacial free energy interactions and surface energy is necessary for understanding and modeling many surface and interface processes. The investigation of the surface properties of solids is very important in several applications such as wetting, spreading and adhesion processes. Such processes occur during the preparation of suspensions, emulsions, painting, printing and corrosion protection. Knowledge about surface free energy of solids appears as a very important parameter determining the interfacial properties in solid/liquid and solid/gas interfaces where many implementations are involved. We have studied the effect of the chemical modification on surface energy for two types of silica: Aerosil OX 50 is chosen as a nanometric substrate and the wafers of silicium chosen as micrometric substrate. For silica OX 50, the chemical modification was carried out using the hydrophobic hexadecyltrichlorosilane (HTS). Transmission infrared and the quantification of organic carbon were helpful in the estimation of increasing quantities of HTS grafted to the surface. Two adsorption isotherms were drawn. Then, continuous adsorption isotherm of argon and nitrogen was used to study the evolution of energetic heterogeneity in the course of the chemical reaction. This was achieved by applying an analysis strategy of the monolayer volume (Vm) of adsorbed argon and nitrogen. Results enabled the drawing of a third adsorption isotherm. The quantification of surface energy for various samples was realize using capillary rise (macroscopic technique) and inverse gas chromatography (IGC) (molecular technique). For silicon wafers, two types of surfaces were elaborated in this study. The first hydrophilic (OH grafting), was obtained by oxidation of silicon wafers (Piranha treatment), the second hydrophobic (CH3 grafting), was obtained by grafting HTS molecules to the surface. The quantification of the surface free energy was achieved using the wettability (macroscopic technique) and the atomic force microscopy (AFM) (nanoscopic technique). Finally the different values of surface free energy obtained for native silica are compared to those of hydrophilic (OH) flat surfaces. As for hydrophobic surfaces, the silica OX 50 modified with maximum quantity of HTS is compared to Hydrophobic (CH3) flat surfaces

Este projeto teve como objetivo geral continuar a avaliar a adequação de anfifílicos que se agregam em solução aquosa formando bicamadas, para recobrir superfícies de sílica. Em paralelo, foi objetivada a reconstituição do reconhecimento receptor-ligante, tendo como modelo o monosialogangliosídio GM1 e a enterotoxina do vibrião da cólera. Os resultados obtidos poderão se mostrar de grande valor em aplicações práticas que envolvem a construção de sistemas de detecção e quantificação de substâncias ou moléculas específicas. A adsorção e estabilidade de bicamadas contendo fosfatidilcolina (PC) ou misturas de brometo de dioctadecildimetilamônio (DODAB) e dipalmitoilfosfatidilcolna (DPPC) sobre a superfície de nanopartículas de sílica foi estudada através de isotermas de adsorção por dosagem do fosfato inorgânico, análises de sedimentação por imagens fotográficas e medidas dos diâmetros médios (Dz) e potenciais-zeta (ζ) de partículas por espectroscopia de correlação de fótons. Foram avaliadas as afinidades entre as bicamadas e a superfície das nanopartículas e a estabilidade do sistema em função da força iônica, do pH e da concentração adicionada de lipídio. A afinidade das bicamadas pela superfície da sílica apresentou uma correlação com as forças de van der Waals e as pontes de hidrogênio que se formam entre os grupos químicos do anfifílico e aqueles de superfície da sílica. A formação de uma única bicamada lipídica de PC sobre a sílica foi detectada, o que levou à estabilidade coloidal do sistema particulado. As bicamadas mistas de DPPC/DODAB por sua vez apresentaram uma afinidade decrescente pela sílica com a elevação da porcentagem de DODAB na bicamada. Os dados de isoterma e de ζ das partículas sugerem uma separação física entre o DPPC e o DODAB. O conjunto otimizado partícula de sílica/bicamada de PC (partícula biomimética) foi assim utilizado para promover a incorporação do GM1 micelar nas bicamadas, medida por fluorescência com a utilização da sonda GM1 pireno, seguida do reconhecimento e ligação da toxina da cólera (CT) ao complexo formado. A transferência do GM1 das micelas para as partículas se mostrou dependente da disponibilidade de bicamadas adsorvidas nestas e da ausência de bicamadas não-adsorvidas, livres em dispersão. Para avaliar a ligação da toxina da cólera às partículas biomiméticas foram calculadas isotermas de adsorção a partir da dosagem de proteína não ligada que resta no sobrenadante. A ligação específica da CT na presença de bicamadas de PC e GM1 foi de 67% em massa do total da proteína adicionada, revelando uma ligação positiva entre receptor e ligante. A estequiometria revela que a proporção molar PC: GM1: CT é de 300: 5: 1 respectivamente. A proporção de 1 CT: 5 GM1 está de acordo com a literatura onde experimentos de difração de raios-X mostram a estrutura tridimensional do pentâmero CTB5 ligado a cinco unidades de pentasacarídeo do GM1. / The general objective of this project was to continue evaluating the suitability of amphiphiles that aggregate in aqueous solution forming bilayers, to cover surfaces of silica. A secondary objective pursued was to promote the reconstitution of the receptor-ligand function, having as a model the monosialoganglioside GM1 and the enterotoxin of the choleric vibrio. The results may prove to be valuable in pure research or practical applications for sensing and detection of biomolecules. The adsorption and stability of phosphatidylcholine (PC) bilayers or mixtures of dipalmitoylphosphatidylcholine (DPPC) and dioctadecyldimethylammonium bromide (DODAB) over surfaces of silica nanoparticles were evaluated through adsorption isotherms by inorganic phosphate dosage, sedimentation analysis by means of photographic images and measurements of hydrodynamic diameter (Dz) and zeta-potentials (ζ) of particles by photon correlation spectroscopy. The affinity between the bilayers and the nanoparticles surfaces and the general system stability were evaluated as a function of ionic strength, pH and added lipid concentration. The affinity showed a correlation with the van der Waals and the hydrogen bridges forces that form between the chemical groups of the amphiphile and the silica surface. The formation of a single lipid PC bilayer over the silica was detected, leading to the colloidal stability of the particulate system. Mixed bilayers of DPPC/DODAB on the other hand showed a decreasing affinity for silica with an increasing DODAB percentage in the bilayer. Data from isotherms and ζ of particles suggests a physical separation of the DPPC and DODAB. The optimized array of silica particle/PC bilayer (biomimetic particles) was thus used to promote the incorporation of micellar GM1 into the bilayers, measured by fluorescence with a GM1 pirene probe, followed by the cholera toxin (CT) binding to the resulting array. GM1 transfer from micelles to particles showed dependence on the adsorbed bilayers availability and on the absence of non-adsorbed bilayers, free in the bulk solution. To evaluate CT binding to biomimetic particles adsorption isotherms were calculated from the dosage of unbound protein remaining in the supernatant. Specific binding of CT in the presence of PC and GM1 bilayer was 67% mass of total protein added, indicating a positive binding between receptor and ligand. Stoichiometry revealed that the molar proportion PC: GM1: CT is 300: 5: 1 respectively. The proportion of 1 CT: 5 GM1 is in good agreement with data in the literature where X-ray diffraction tests show the 3-dimensional structure of the CTB5 pentamer bound to five units of the pentasaccharide GM1.

Cette étude vise à définir l'effet des lipoprotéines de basses densité natives (LDL) et oxydées (ox-LDL) sur les fonctions des cellules endothéliales en relation avec les processus physiopathologiques de l'athérosclérose. Le microscope à force atomique (AFM) fut utilisé en combinaison avec les méthodes biochimiques traditionnelles afin d'acquérir de l'information sur les propriétés biomécaniques des cellules endothéliales. L'AFM est un outil permettant l'acquisition d'images et de mesures de forces quantitatives concernant les propriétés viscoélastiques des cellules vivantes selon leur exposition aux LDL ou ox-LDL. L'AFM rassemble localement des informations sur la membrane cellulaire et le cytosquelette des cellules et ce, de manière non invasive. Il est ensuite possible de corréler les résultats obtenus avec les marquages immunohistochimiques afin d'évaluer la réponse cellulaire suite à une exposition à des LDL ou ox-LDL. Ces données recueillies, les protocoles étant au point, il ne restera plus qu'à effectuer les tests avec les antioxydants afin de déterminer les agents et les dosages appropriés permettant une protection salutaire de l'endothélium. Ce travail amène donc de nouvelles connaissances sur les mécanismes moléculaires fondamentaux de la dysfonction endothéliale en vue éventuellement de développer de nouvelles thérapies cytoprotectrices efficaces. Une méthode d'imagerie des LDL a également été mise au point en utilisant l'AFM. Il est maintenant possible d'obtenir des images de bonne qualité permettant aussi de mesurer les dimensions de LDL individuelles. Cette technique pourrait entre autre servir à évaluer des pathologies touchant les LDL comme le diabète.