The apoptosis and dysfunction of vascular smooth muscle cells in the human descending thoracic aorta is often associated with cardiovascular diseases like aortic dissection and aneurysms. Knowledge of the mechanical effects of contractile smooth muscle cells plays a crucial role in the understanding these potentially lethal conditions. Located in the medial layer, vascular smooth muscle cells are arranged in the so-called herringbone pattern. In regards to the mechanics of the aorta, the consequences of this type of anisotropy have not been fully discussed in literature so far. In this end, a novel hyperelastic constitutive law is proposed which accounts for the dispersive, transmural alignment of vascular smooth muscle cells and their characteristic length-tension behaviour. The model is calibrated with experimental data and is applied to the simulation of an aortic ring under in vivo conditions. By approximating the geometry of the aorta as a layered, thick-walled cylinder, the corresponding quasistatic, mechanical boundary value problem is solved semi-analytically. It is shown that the herringbone pattern induces shear deformation and equalises the normal stress gradients in the aortic wall. Since arterial vessels are able to actively adapt and alter the alignment and activity of smooth muscle cells, the existence of the herringbone pattern is in accordance with Fung's principle of optimal operation.

Three-dimensional (3D) turbulent boundary layers (TBLs) play a crucial role in determining the aerodynamic properties of most aero-mechanical devices. However, accurately predicting these flows remains a challenge due to the complex nonlinear and nonlocal physics involved, which makes it difficult to develop universally applicable models. This limitation is particularly significant as the industry increasingly relies on simulations to make decisions in high-consequence environments, such as the certification or aircraft, and high-fidelity simulation methods that don't rely on modeling are prohibitively expensive. To address this challenge, it is essential to gain a better understanding of the physics underlying 3D TBLs. This research aims to improve the predictive accuracy of turbulence models in 3D TBLs by examining the impact of model assumptions underpinning turbulent constitutive relations, which are fundamental building blocks of every turbulence model. Specifically, the study focuses on the relevance and necessity of nonlinear and nonlocal model assumptions for accurately predicting 3D TBLs. The study considers the attached 3D boundary layer flow over the textbf{Be}nchmark textbf{V}alidation textbf{E}xperiment for textbf{R}ANS/textbf{L}ES textbf{I}nvestiagtions (BeVERLI) Hill as a test case and corresponding particle image velocimetry data for the investigation. In a first step, the BeVERLI Hill experiment is comprehensively described, and the important characteristics of the flow over the BeVERLI Hill are elucidated, including complex symmetry breaking characteristics of this flow. Reynolds-averaged Navier-Stokes simulations of the case using standard eddy viscosity models are then presented to establish the baseline behavior of local and linear constitutive relations, i.e., the standard Boussinesq approximation. The tested eddy viscosity models fail in the highly accelerated hill top region of the BeVERLI hill and near separation. In a further step, several nonlinear and nonlocal turbulent constitutive relations, including the QCR model, the model by Gatski and Speziale, and the difference-quotient model by Egolf are used as metrics to gauge the impact of nonlinearities and nonlocalities for the modeling of 3D TBLs. It is shown that nonlinear and nonlocal approaches are essential for effective 3D TBL modeling. However, simplified reduced-order models could accurately predict 3D TBLs without high computational costs. A constitutive relation with local second-order nonlinear mean strain relations and simplified nonlocal terms may provide such a minimal model. In a final step, the structure and response of non-equilibrium turbulence to continuous straining are studied to reveal new scaling laws and structural models. / Doctor of Philosophy / Airplanes and other flying objects rely on the way air flows around them to generate lift and stay in the sky. This airflow can be very complex, especially close to the surface of the object, where it is affected by friction with the object. This friction generates a layer of air called a boundary layer, which can become turbulent and lead to complex patterns of airflow. The boundary layer is generated by the friction between the air and the surface of the object, which causes the air molecules to "stick" to the surface. This sticking creates a layer of slow-moving air that slows down the flow of air around the object. This loss of momentum creates drag, which is one of the main factors that resist the motion of objects in the air. The slowing of the air flow in the boundary layer is due to the viscosity of the air, which is a measure of how resistant the air is to deformation. The molecules in the air have a tendency to stick together, making it difficult for them to move past each other. This resistance causes the momentum of the air to be lost as it flows over the surface of the object because air molecules close to the surface "pull" on the ones farther away. Understanding how turbulent boundary layers (TBLs) work is essential to accurately predict the airflow around these objects using computer simulations. However, it's challenging because TBLs involve complex physics that are difficult to model accurately. This research focuses on a specific type of TBL called a three-dimensional (3D) TBL. This study looks at how different assumptions affect the accuracy of computer simulations that predict this type of airflow. It is found that using more complex models that take into account nonlinear and nonlocal physics can help predict 3D TBLs more accurately. However, these models are computationally expensive, and it is also found that simpler models can work well enough and are cheaper. This research further establishes important physical relations of the mechanisms pertaining 3D TBLs that could support the advancement of current models.

Various constitutive formulations can be employed to simulate the coupled behaviour of electro-active polymers (EAP). Those distinct mathematical descriptions vary with respect to the manner in which the electric field is coupled to the deformation. However, in principle, they are all capable of emulating the finite coupled response of EAP. The underlying coupling mechanism of largely deformable materials can be identified through experimental characterization. This contribution addresses the constitutive and finite element modelling of the actuation response of both isotropic and anisotropic EAP, where different material formulations are considered and implemented within a finite element framework. Those various material formulations are mathematically treated and employed to simulate electro-mechanical experiments of dielectric materials. Existing coupled electro-mechanical tests of active materials are referred to, where it is sought to employ different constitutive models to fit the experimental observations. Within the undertaken study, the capability of different descriptions to predict electro-mechanical instabilities is evaluated. Regarding the numerical implementation of the model, it is referred to an electro-mechanical Q1P0 finite element formulation. After performing the study and fitting experimental results associated to isotropic materials, the actuation response of several anisotropic EAP-based structures is emulated.

The introductions of large digital computers in the field of engineering have rendered possible the solution of a wide variety of problems without the need to violate the equilibrium and compatibility. The major requirement for such analysis is a good constitutive model that represents the stress strain behaviour of the materials in an accurate way. Nowadays for most of the geotechnical engineering applications the elastoplastic models like Mohr Coulomb model are widely used. All the existing constitutive models which represent the plastic behaviour of soil are developed from the fundamentals of classical theory of plasticity. The classical theory of plasticity is always associated with the concept of yield surface and potential surface to represent the plastic behaviour. The definition of yield surface depends on the location of the yield point. But in practical sense it is very difficult to find out the exact yield point for a material. The expression for yield and potential surfaces are simply mathematical expressions formulated for computational efficiency. Experimentally it is very difficult to find out the yield surface in the case of three dimensional stress spaces. The classical theory of plasticity is developed based on the mechanical process. It is believed that a theory which violates the thermodynamic principle is not able to represent the material behaviour accurately. the initial stage and combined to give the final state of stress. It was proved that the equation proposed by Wu and Wang (1983) can be used to represent the triaxial behaviour of sand very well. The dilation and densification behaviour can be predicted very well with the endochronic constitutive equations. The principal aim of this work is to implement the endochronic constitutive equation in the FLAC3D model library like any other constitutive model and validate it with the triaxial test data. After implementation and validation, the application of the particular constitutive model is extended to some practical geotechnical engineering problems like the stresses and displacements around an underground opening such as tunnels, surface settlement due to shallow tunneling, stress distribution below the footing, settlement analysis of footing on various foundation beds such as sand, clay and sand overlying clay bed, lateral displacement of the secant pile wall due to excavation and the force developed in the horizontal support etc. All the three problems validate the model with the analytical, experimental and field data respectively. The equation proposed by Wu and Wang (1983) is used for the present study. In order to validate the equation proposed by Wu and Wang (1983), MatLab programming is used. The hydrostatic, deviatoric and volumetric behaviour is obtained separately using the concerned equations. The equation is coded in the MatLab and analysis is done for a triaxial element test. Both drained and undrained analyses were done in order to study the behaviour. The pore pressure developed is captured separately with the equation proposed by Geoffrey et al (1975). The results obtained from the analysis of the MatLab were compared with that of the experimental results. The analysis shows that the equation captures the least plastic behaviour well for the triaxial element test. The dilation and densification behaviour obtained using the respective equation shows that it matches well with the experimental results. A parametric study is also conducted in MatLab to see how the parameters affect the stress strain and volumetric behaviour of the sand. The parametric study conducted with the MatLab shows that most of the parameters involved in the equation affect the plastic part of the stress strain curve rather than the initial elastic part. User defined constitutive model was written in visual C++ and compiled as DLL (Dynamic Link Library) files that will be loaded whenever it is needed in FLAC3D. In visual C++, header and source files were written by incorporating the constitutive equation proposed by Wu and Wang (1983), defining the variables and other functions etc, and a dynamic link library is created, which is then integrated into the 3D finite difference code FLAC3D using the CPPUDM module to simulate the stress strain behaviour of the materials. CPPUDM module is an additional option in FLAC3D to implement the user defined constitutive models. The visual C++ code was written in the form of incremental stress strain relationship. The model acts like any other constitutive model in the FLAC3D model library and can be loaded whenever it is required. For the validation of the model in FLAC3D, the data for the MatLab simulation were used. Both drained and undrained tests were simulated with the model. The results obtained from the analysis shows that by suitably selecting the parameters the model can simulate the stress strain behaviour of sand very well. The volumetric and deviatoric behaviour were observed and is matching well with the experimental data. In the case of the undrained test the pore pressure generation is well captured by the equation proposed by Geoffrey et al (1975). In urban areas the construction of shallow tunnels results in excessive settlements of the ground surface and thereby causes damage to the existing above ground structures. In order to minimize the settlements and to reduce the impact due to that, a prior analysis of the displacements and stresses around the opening is very important. Nowadays numerical analysis is widely used for the analysis of such structures. The most important requirement of such analysis is a constitutive model that can represent the unloading behaviour around the tunnel opening of sand very well. Here the endochronic constitutive model implemented in the FLAC3D model library is used to evaluate the stresses and displacements around the tunnel. In the analysis the tunnel is simulated as a cylindrical hole in an infinite medium with the in situ stress. The stresses at the springing line was observed and compared with the analytical solution. The results show that the results are matching well with the analytical results. The comparison of the results with that obtained using the Mohr Coulomb model is also done to see how the model differs from a widely used plastic model. By slightly adjusting the parameters the results obtained from both the models are in well agreement. The strain softening effect which is predominant around an underground opening due to the loosening of soil mass is well captured by the endochronic model compared to the Mohr Coulomb model. The settlement analysis shows that the model is almost in close agreement with the closed form solution proposed by Oteo & Sagaseta (1982) and the results obtained with the Mohr Coulomb model. The settlement trough formed for various shapes is wider and deeper than the Mohr Coulomb model. The vertical stress distribution around the opening of the tunnel is studied with varying the shape of the openings using the proposed constitutive model. The results obtained were compared with that of the Mohr Coulomb model. The slightly higher values in the case of endochronic model are basically due to its plastic nature. The displacement and stresses in the axial direction (along the excavation) is observed with the model. In the case of shallow tunnel the surface get influenced by the loosening of the soil mass which necessitates the use of the support system. The study shows that the model can be used for the simulation of underground opening like tunnel and will capture the behaviour well. Footings are structures used to support the buildings constructed above the ground. The settlement analysis of footings is very important when we consider the stability of the structures supported by it. The vertical stress distribution below the footing is studied using the endochronic constitutive model and compared with the analytical solution proposed by Boussinesq (1885). In the elastic range the model shows matching results with the Boussinesq’s solution. The settlement analysis of footing on various foundation beds such as sand, clay and sand overlying the clay bed were studied using the endochronic constitutive model implemented in the FLAC3D model library. The experimental data conducted in our lab (Sireesh (2006)) was used for the study. The results show that with the chosen parameters the results obtained with the endochronic model are in good agreement with the experimental data. The Mohr Coulomb model over predicts the results. This shows higher modulus value for the Mohr Coulomb model. By conducting the parametric study it was seen that by reducing the value of modulus for the Mohr Coulomb model, the results are in good agreement with the experimental value. The displacement and stress contours obtained for the two models were compared. By analyzing the displacement contours it is seen that the Mohr Coulomb model shows uniform settlement. In the case of endochronic model uniform settlement is observed for about 5% settlement that is in the elastic range. After a certain strain level the displacement contours are tilted more towards one side showing the rotational failure. Here the endochronic model captures the anisotropic behaviour associated with the materials like sand at higher strain level. This result is a concrete evidence that the model can capture the realistic behaviour very well compared to any other model. Even though the model developed is for sand its application can be extended to clay also. The size and shape of the footing is varied to study its effect on the pressure settlement curve. The analysis is done with square shape of 150mm side and circular shape of 150mm diameter. As there is not much variation in the area of influence, the shape has little influence on the pressure settlement curve. As the size of the footing increases the settlement increases for a given pressure. A parametric study is conducted by varying the modulus value used. The study shows that as the modulus value increases, the settlement reduces for a given bearing pressure. The endochronic model analysed with the lower modulus value shows that the model predicts the perfectly plastic behaviour, here the settlement increases for low value of bearing pressure. The application of endochronic model for the simulation of complex geotechnical engineering problems like footings is highly explored in the study. Nowadays most of the infrastructure facilities are concentrated towards the underground space. The excavation and construction of such structures in the urban areas results in damage to the existing above ground structures if the construction is done in close proximity to the structures. In the present study a staged excavation of an underground construction for the Bangalore metro project is simulated with the endochronic constitutive model. In the Bangalore metro project the excavation for the underground station is done at the cricket stadium site. At the site there are two major buildings such as the six storied Hindustan Aeronautical Limited building and 100 years old BSNL masonry building. To minimize the impact on these structures were a major concern during the construction of the work. A robust support system consists of secant pile walls, soldier piles and horizontal struts are installed at the site. The OSV method known as the Onsite Visualization and monitoring is conducted to minimize the damage to the existing structures and the accidents at the construction site. Sensors are connected to LEDs which show change in color when the displacements and forces cross the triggered value. The field instrumentation is done with inclinometers, tilt meters and strain gauges connected to the sensors to observe the lateral deformation of the secant pile wall, tilt of the HAL building and the forces developed in the horizontal struts. The monitoring of field data is done for a period of five months from July to November. From the analysis of the field observed data it is clear that the support system provided were strong enough to resist the forces due to unloading. The lateral deformation of the secant pile wall and the forces developed in the strut were numerically analysed using the endochronic constitutive model and the results were compared with the field monitored data. The results show that the model captures the behaviour very close to the field data for a slightly higher modulus than that reported in the geotechnical report (BMRC report). This may be due to the fact that the value of modulus calculated experimentally might have some error. The analysis with the Mohr Coulomb model shows that the model over predicts the results very close to the surface of the excavation. This indicates that the influence of load is more on that particular depth for the Mohr Coulomb model. But the stiffness of the lateral support system is uniform throughout the depth; the endochronic model predicts the result more accurately than the Mohr Coulomb model. The strut forces developed in the horizontal support system is observed using the two models. The strut forces in the field is affected by so many factors such as the temperature variation, stages of excavation and other live loads acting on the site, so an exact comparison with the field data is quite difficult. The analysis shows that even though it is difficult to simulate the exact three dimensional nature of the problem in the present study the endochronic constitutive model captures the behaviour very well. The results obtained shows that the endochronic constitutive model implemented in the FLAC3D model library provides a very promising solution like any other constitutive model. As the theory is based on the irreversible law of thermodynamics and the formulation of the constitutive equation are based on the internal energy concept it can represent the material behaviour in accordance with the laws of continuum mechanics. The anisotropic behaviour of soil at higher strain level is well represented through the footing problem. The endochronic constitutive model is a very simple one to simulate the stress strain behaviour of the materials without the concept of yield surface; the parameters used in the equation can be obtained directly from a single triaxial stress strain plot. This study highlights the importance of a model without the concept of yield surface to capture the stress strain behaviour of any materials. Since the model is of completely plastic nature it has its own uniqueness in capturing the material behaviour due to loading and unloading.

No description available.

La leucémie myéloïde aiguë (LMA) est causée par une prolifération anormale de cellules souches sanguines immatures. Notre laboratoire se concentre sur un sous-groupe de la LMA représentant près de 30% de la LAM pédiatrique et caractérisé par la translocation chromosomique KMT2A-MLLT3. L'analyse par séquençage de l’ARN (RNA-seq) dans notre modèle de LMA médiée par la fusion KMT2A-MLLT3 et des échantillons de patients leucémiques a révélé que les gènes codant la chimiokine CCL23 et son récepteur correspondant CCR1 sont surexprimés dans cette maladie. Bien qu'il ait été rapporté que CCL23 et CCR1 sont impliqués dans le trafic de leucocytes et le développement de l'inflammation, les rôles exacts de ces deux protéines dans la leucémogenèse sont inconnus. Pour illustrer les effets de la signalisation CCL23/CCR1 dans la leucémie causée par la fusion KMT2A-MLLT3, nous avons utilisé la technique de transfert d'énergie de résonance de bioluminescence 2 améliorée (ebBRET2) avec des tests d'immuno-empreintes. Nos résultats ont révélé que la signalisation de l'axe CCL23/CCR1 active plusieurs effecteurs de signalisation intermoléculaire, y compris Gi2, G12/13 et β-arrestine 1/2, mais avec un biais vers le recrutement de la β-arrestine. Nous avons également montré que le récepteur CCR1 présente une activité constitutive qui peut se coupler à une voie médiée par la protéine G et activer la voie impliquant les MAP kinases. Enfin, nous avons montré que la signalisation de l'axe CCL23/CCR1 provoque une activation de ERK1/2 dans les lignées cellulaires LMA potentiellement par une voie médiée par la β-arrestine. Ces résultats indiquent que la signalisation de l'axe CCL23/CCR1 active plusieurs voies biologiques pouvant fournir des avantages majeurs pour le développement et la progression de la LMA et présentent ainsi CCL23 et CCR1 comme deux candidats intéressants pour une thérapie ciblée contre la LMA de type KMT2A-MLLT3. / Acute Myeloid Leukemia (AML) is caused by abnormal proliferation of immature blood stem cells. Our lab focuses on an AML subgroup accounting for almost 20% of pediatric AML and characterized by a chromosomal translocation that generates the gene fusion: KMT2A-MLLT3 (KM3). Interestingly, RNA-seq analysis of our KM3 AML model and AML patient samples has revealed that the chemokine CCL23 and its corresponding receptor CCR1 are highly upregulated in this disease. Although it has been reported that CCL23 and CCR1 are implicated in leukocyte trafficking and development of inflammation, the exact roles of these two proteins in leukemia are unknown. To illustrate the effects of CCL23/CCR1 signaling in the KMT2A-MLLT3 rearranged leukemia we employed the enhanced bystander bioluminescence resonance energy transfer 2 (ebBRET2) technique along with phospho-immunoblots assays. Our results revealed that CCL23/CCR1 axis signaling activates multiple intermolecular signaling effectors, including Gi2, G12/13, and β-arrestin1/2 albeit with a bias towards β-arrestin recruitment. We also showed that the CCR1 receptor exhibits a constitutive activity which can couple to a G-protein mediated pathway to activate the MAPK cascade. Finally, we showed that CCL23/CCR1 axis signaling causes an activation of ERK1/2 in AML cell lines potentially through a β-arrestin-mediated pathway. These results indicate that the CCL23/CCR1 axis signaling activates several biological pathways than can provide major advantages for the AML disease development and progression thus presenting both CCL23 and CCR1 as interesting candidates for targeted therapy against KMT2A-MLLT3 AML.

There is enough evidence on how climate change consequences will adversely affect Africa despite the fact that it is the continent that has least contributed to the problem. The international climate change regime recognises Africa's vulnerability to climate change and provides for special treatment under the United Nations Framework Convention on Climate Change (the UNFCCC). Thus, the international climate change regime presents an opportunity for African countries to adapt and mitigate the consequences of climate change through the UNFCCC mechanism. However, the international climate change legal regime has not been able to adequately assist African countries to address the consequences of climate change under the vulnerability principle. Although the current international climate change regime requires developed countries to reduce their greenhouse gas (GHG) emissions, Africa needs to take steps itself to address the problem, because it is most vulnerable to the consequences of climate change. The African Union (AU) could play a great role in ensuring that the international climate change regime addresses the consequences of climate change in the region. This could be done through fostering strong African common positions during international climate change negotiations. A strong common position could strengthen African bargaining power and might result in more funding, capacity building and technology development and transfer for adaptation and mitigation programmes under the UNFCCC-Kyoto Conference of Parties. However, reaching a strong common position requires the cooperation of the AU member states. In this context, African regional integration is an opportunity for the AU to foster such cooperation among member states. The Treaty Establishing the African Economic Community (the Abuja Treaty), the Constitutive Act of the AU and the Protocol on the Relations between the AU and Regional Economic Communities (RECs) prioritise regional economic integration and call for states' cooperation, but the call has not yet been heeded. To realise deep and viable African integration, there must be a well-structured institutional and legal framework that defines the relationship between the AU, the AEC and the RECs. African regional integration is also seen as an avenue whereby the AU can create its own regional climate-change regime. In this regard, the AU's and RECs' normative framework on climate change is examined in order to assess whether it adequately integrates climate change issues. This study finds that although Africa is most vulnerable to the consequences of climate change, the AU's and RECs' normative framework on climate change is weak and inadequate to address the problem. The Framework should integrate climate change issues in order to achieve sustainable development. The AU should also ensure that member states ratify the relevant treaties and protocols (the Maputo Nature Convention and the Protocol establishing the African Court of Justice and Human Rights) that have not yet been ratified in order that they may become operational. The Maputo Nature Convention puts sustainable development in the forefront of attention as a reaction to the potentially conflicting environmental and developmental challenges facing the continent (such as climate change), but it is not yet in force. This work finds that human rights law can strengthen the AU's role in addressing climate change through its normative framework. The human rights approach to climate change under the African Charter on Human and Peoples' Rights (the Banjul Charter) is a viable avenue because human rights law forms the basis for states' responsibility based on human rights obligations and principles. The extraterritorial application of the Banjul Charter presents an avenue for AU institutions such as the Human Rights Commission and the African Human Rights Court to curb the effects of climate change through a human rights lens. The future of the AU is presented within the context of a set of recommendations that identify strong African regional integration as an avenue through which the AU can foster the cooperation of member states to address the consequences of climate change in the AU's and RECs' normative frameworks. General recommendations are made on the need for the international climate change regime to pay more attention to issues of funding, capacity building and technology development and transfer on the basis of the vulnerability principle and in relation to the principles of equity and common but differentiated responsibilities and respective capabilities. Also, the AU needs to strengthen its legal and institutional structures to ensure deep African integration that is capable of addressing common challenges such as the consequences of climate change. / PhD (Law), North-West University, Potchefstroom Campus, 2014

There is enough evidence on how climate change consequences will adversely affect Africa despite the fact that it is the continent that has least contributed to the problem. The international climate change regime recognises Africa's vulnerability to climate change and provides for special treatment under the United Nations Framework Convention on Climate Change (the UNFCCC). Thus, the international climate change regime presents an opportunity for African countries to adapt and mitigate the consequences of climate change through the UNFCCC mechanism. However, the international climate change legal regime has not been able to adequately assist African countries to address the consequences of climate change under the vulnerability principle. Although the current international climate change regime requires developed countries to reduce their greenhouse gas (GHG) emissions, Africa needs to take steps itself to address the problem, because it is most vulnerable to the consequences of climate change. The African Union (AU) could play a great role in ensuring that the international climate change regime addresses the consequences of climate change in the region. This could be done through fostering strong African common positions during international climate change negotiations. A strong common position could strengthen African bargaining power and might result in more funding, capacity building and technology development and transfer for adaptation and mitigation programmes under the UNFCCC-Kyoto Conference of Parties. However, reaching a strong common position requires the cooperation of the AU member states. In this context, African regional integration is an opportunity for the AU to foster such cooperation among member states. The Treaty Establishing the African Economic Community (the Abuja Treaty), the Constitutive Act of the AU and the Protocol on the Relations between the AU and Regional Economic Communities (RECs) prioritise regional economic integration and call for states' cooperation, but the call has not yet been heeded. To realise deep and viable African integration, there must be a well-structured institutional and legal framework that defines the relationship between the AU, the AEC and the RECs. African regional integration is also seen as an avenue whereby the AU can create its own regional climate-change regime. In this regard, the AU's and RECs' normative framework on climate change is examined in order to assess whether it adequately integrates climate change issues. This study finds that although Africa is most vulnerable to the consequences of climate change, the AU's and RECs' normative framework on climate change is weak and inadequate to address the problem. The Framework should integrate climate change issues in order to achieve sustainable development. The AU should also ensure that member states ratify the relevant treaties and protocols (the Maputo Nature Convention and the Protocol establishing the African Court of Justice and Human Rights) that have not yet been ratified in order that they may become operational. The Maputo Nature Convention puts sustainable development in the forefront of attention as a reaction to the potentially conflicting environmental and developmental challenges facing the continent (such as climate change), but it is not yet in force. This work finds that human rights law can strengthen the AU's role in addressing climate change through its normative framework. The human rights approach to climate change under the African Charter on Human and Peoples' Rights (the Banjul Charter) is a viable avenue because human rights law forms the basis for states' responsibility based on human rights obligations and principles. The extraterritorial application of the Banjul Charter presents an avenue for AU institutions such as the Human Rights Commission and the African Human Rights Court to curb the effects of climate change through a human rights lens. The future of the AU is presented within the context of a set of recommendations that identify strong African regional integration as an avenue through which the AU can foster the cooperation of member states to address the consequences of climate change in the AU's and RECs' normative frameworks. General recommendations are made on the need for the international climate change regime to pay more attention to issues of funding, capacity building and technology development and transfer on the basis of the vulnerability principle and in relation to the principles of equity and common but differentiated responsibilities and respective capabilities. Also, the AU needs to strengthen its legal and institutional structures to ensure deep African integration that is capable of addressing common challenges such as the consequences of climate change. / PhD (Law), North-West University, Potchefstroom Campus, 2014

Thesis (MEd (Education Policy Studies))--University of Stellenbosch, 2009. / This thesis explores pluralist perspectives on literacy in the context of the Literacy and Numeracy (LITNUM) Strategy of the Western Cape Education Department. My argument is that we need to move beyond functional or technical conceptions of literacy towards a recognition of its transformative potential. That is, the concept of literacy needs to be stretched to incorporate pluralist perspectives in order to achieve developmental aspirations. Following a literature review approach, I construct three constitutive meanings of literacy, namely “cognitive skills”, “social context” and “development”, and I investigate how the LITNUM Strategy conforms to these constitutive meanings of literacy. My finding is that LITNUM is based on a constructivist learning theory. I caution that when understandings of learning theories are viewed exclusively from one perspective, literacy becomes “compacted”, and we miss out on important considerations of literacy and its transformative potential. I show that LITNUM discusses several social contextual factors related to literacy; a recognition of the impact of social issues on literacy. Regarding LITNUM’s concern with development, I conclude that both functional and critical literacy as important aspects of development are not sufficiently addressed. In a nutshell: LITNUM focuses on technical skills, which need to be balanced with the notion that literacy is a social act, and that it has the potential to transform societies. I propose a “literacy of thoughtfulness”, based on compassion, love and care. This proposition forms the basis for possible future research.

Cette thèse porte sur la rhéologie des pâtes granulaires. L'image classique pour les pâtes granulaires est qu'il y a une transition d'un écoulement frictionnel vers un écoulement lubrifié lors de l'augmentation du taux de cisaillement. Nous montrons qu'il existe en réalité une transition d'un écoulement localisé vers un écoulement non-localisé. Le paramètre pertinent caractérisant cette transition est le nombre de Leighton, qui est le rapport entre les forces lubrifiée et frictionnelle. Ce nombre définit un taux de cisaillement critique au-dessous duquel aucun écoulement stationnaire sans localisation ne peut exister. Par ailleurs, en menant à la fois des expériences en IRM et des expériences de rhéologie classique, nous définissons une viscosité pour les pâtes granulaires. Il faut pour cela tenir compte de la migration des particules vers les zones faiblement cisaillées lors de l'écoulement, migration qui engendre un profil de concentration des particules. La viscosité est donnée par une loi constitutive constituée de trois équations : l'équation de la courbe d'écoulement, l'équation de Krieger-Dougherty, et le rapport entre contrainte de cisaillement et première différence de contraintes normales. Enfin, nous étudions des suspensions rhéoépaississantes de fécule de maïs qui présentent également une transition d'un régime localisé vers un régime non-localisé autour d'un seuil de rhéoépaississement.