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Over one million amputees are living in the United States with major lower limb loss (Ziegler-Graham et al. 2008). Lower limb amputation leads to the functional loss of the ankle plantar flexor muscles, which are important contributors to body support, forward propulsion, and leg swing initiation during walking (Neptune et al. 2001; Liu et al. 2006). Effective prosthetic component design is essential for successful rehabilitation of amputees to return to an active lifestyle by partially replacing the functional role of the ankle muscles. The series of experimental and computer simulation studies presented in this research showed that design characteristics of energy storage and return prosthetic ankles, specifically the elastic stiffness, significantly influence residual and intact leg ground reaction forces, knee joint moments, and muscle activity, thus affecting muscle output. These findings highlight the importance of proper prosthetic foot stiffness prescription for amputees to assure effective rehabilitation outcomes. The research also showed that the ankle muscles serve to stabilize the body during turning the center of mass. When amputees turn while supported by their prosthetic components, they rely more on gravity to redirect the center of mass than active muscle generation. This mechanism increases the risks of falling and identifies a need for prosthetic components and rehabilitation focused on increasing amputee stability during turning. A proper understanding of the effects of prosthetic components on amputee walking mechanics is critical to decreasing complications and risks that are prevalent among lower-limb amputees. The presented research is an important step towards reaching this goal. / text

Le flot de Ricci est une équation aux dérivées partielles qui régit l’évolution d’une métrique riemannienne dépendant d’un paramètre de temps sur une variété différentielle. D’abord introduit et étudié par R. Hamilton, il est à l’origine de la solution de la conjecture de géométrisation des variétés compactes de dimension 3 par G. Perelman en 2001. La théorie classique concernant l’existence en temps court des solutions, due à Hamilton et à Shi, garantit (en dimension quelconque) l’existence d’un flot soit sur une variété compacte, soit lorsque la métrique initiale est complète avec une borne sur la norme du tenseur de courbure. En l’absence de cette borne, on conjecture qu’on peut trouver, à partir de la dimension 3, des données initiales pour lesquelles il n’existe pas de solution. Dans cette thèse, on démontre des théorèmes d’existence en temps court du flot sous des hypothèses plus faibles qu’une borne sur la norme du tenseur de courbure. Pour cela, on introduit une construction générale qui, pour une métrique riemannienne g quelconque sur une variété M, pas nécessairement complète, permet de produire une solution de l’équation du flot sur un domaine ouvert D de l’espace-temps M * [0,T] qui contient la tranche de temps initiale, avec g pour donnée initiale. On montre ensuite que sous des hypothèses adaptées sur la métrique g, on contrôle la forme du domaine D. En particulier, lorsque la métrique g est complète, D contient un ensemble de la forme M * [0,t], avec t>0, ce qui revient à dire qu’il existe un flot au sens classique dont la donnée initiale est g. Les « hypothèses adaptées » qui conduisent à des théorèmes d’existence sont de trois types. Dans tout les cas, on suppose une minoration uniforme du volume des boules de rayon au plus 1, à quoi on ajoute : a) en dimension 3, une minoration du tenseur de Ricci, b) en dimension n, une minoration d’une notion de courbure dite « courbure isotrope I » ou bien c) en dimension n, une borne sur la norme du tenseur de Ricci et une hypothèse qui garantit la proximité au sens métrique des boules de rayon au plus 1 avec une boule de même rayon dans un espace métrique obtenu comme le produit cartésien d’un espace de dimension 3 et d’un facteur euclidien de dimension n-3. De plus, avec ces résultats d’existence viennent des estimations sur les propriétés de régularisation du flot quantifiées en fonction des hypothèses sur la donnée initiale. La possibilité ainsi offerte de régulariser, globalement ou localement, pour un temps et avec des estimations quantifiés, une métrique initiale a des conséquence sur les espaces métriques singuliers obtenus comme limites, pour la distance de Gromov-Hausdorff, de suites de variétés satisfaisant uniformément aux conditions a), b) ou c). En effet, des théorèmes de compacité classiques pour le flot de Ricci permettent d’extraire un flot limite, étant donnée une suite de métriques initiales satisfaisant uniformément à ces hypothèses, et possédant donc toutes un flot pour un temps contrôlé. Lorsque les métriques en question approchent, pour la topologie de Gromov-Hausdorff, un espace singulier, cette solution limite s’interprète comme un flot régularisant l’espace singulier en question, et son existence contraint la topologie de cet espace singulier. / The Ricci Flow is a partial differential equation governing the evolution of a Riemannian metric depending on a time parameter t on a differential manifold. It was first introduced and studied by R. Hamilton, and eventually led to the solution of the Geometrization conjecture for closed three-dimensional manifolds by G. Perelman in 2001. The classical short-time existence theory for the Ricci Flow, due to Hamilton and Shi, asserts, in any dimension, the existence of a flow starting from any initial metric when the underlying manifold in compact, or for any complete initial metric with a bound on the norm of the curvature tensor otherwise. In the absence of such a bound, though, the conjecture is that starting from dimension 3 one can find such initial data for which there is no solution. In this thesis, we prove short-time existence theorems under hypotheses weaker than a bound on the norm of the curvature tensor. To do this, we introduce a general construction which, for any Riemannian metric g (not necessarily complete) on a manifold M, allows us to produce a solution to the equation of the flow on an open domain D of the space-time M * [0,T] which contains the initial time slice, with g as an initial datum. We proceed to show that under suitable hypotheses on g, one can control the shape of the domain D, so that in particular, D contains a subset of the form M * [0,t] with t>0 if g is complete. By « suitable hypothesis », we mean one of the following. In any case, we assume a lower bound on the volume of balls of radius at most 1, plus a) in dimension 3, a lower bound on the Ricci tensor, b) in dimension n, a lower bound on the so-called « isotropic curvature I » or c) in dimension n, a bound on the norm of the Ricci tensor, as well as a hypothesis which garanties the metric proximity of every ball of radius at most $1$ with a ball of the same radius in a metric product between a three-dimensional metric space and a $n-3$ dimensional Euclidian factor. Moreover, with these existence results come estimates on the existence time and regularization properties of the flow, quantified in term of the hypotheses on the initial data. The possibility to regularize metrics, locally or globally, with such estimates has consequences in terms of the metric spaces obtained as limits, in the Gromov-Hausdorff topology, of sequences of manifolds uniformly satisfying a), b) or c). Indeed, the classical compactness theorems for the Ricci Flow allow for the extraction of a limit flow for any sequence of initial metrics uniformly satisfying the hypotheses and thus possessing a flow for a controlled amount of time. In the case when these metrics approach a singular space in the Gromov-Hausdorff topology, such a limit solution can be interpreted as a flow regularizing the singular limit space, the existence of which puts constraints on the topology of this space.

Materiais vítreos com propriedades similares às do cristal germanato de bismuto de composição Bi4Ge3O12, material cintilador que possui estrutura do tipo eulitita, são de interesse devido as suas propriedades luminescentes, que os tornam promissores para aplicação como dispositivos ópticos. Vidros do sistema GeO2-Bi2O3 (BGO) também tem sido tema de inúmeras pesquisas por combinarem um típico formador vítreo (GeO2) a um formador condicional composto intermediário (Bi2O3), o que os proporciona características estruturais únicas, resultantes da mudança de coordenação dos átomos de germânio (fenômeno de anomalia do germânio) e também dos átomos de bismuto. Neste trabalho, estudou-se a influência da adição de CeO2, comumente conhecido como agente oxidante, nas propriedades físico-químicas de vidros de germanato de bismuto do sistema [100-x].[(1-y)GeO2-yBi2O3]:xCeO2 (para x = 0,2 ou 1 e y = 0,2 ou 0,3 % em mol), preparados pelo método de fusão e moldagem. O escurecimento inomogêneo das amostras, associado à termoredução do íon Bi3+, foi evitado com a adição de céria, que se mostrou um modificador da estrutura local dos vidros, mesmo para uma dopagem de 0,2 % em mol. Foi observada, pela primeira vez, a cristalização da fase de estrutura eulitita cintiladora induzida pela presença de Ag na superfície do vidro de composição 99,8[0,8GeO2- 0,2Bi2O3 ]:0,2CeO2 % em mol, referido pela sigla 80BGO:0,2Ce, abaixo da temperatura de transição vítrea (Tg). A difusão de Ag no vidro é condição necessária para que o fenômeno da cristalização aconteça, uma vez que esse elemento pode ser considerado um efetivo agente nucleante para a fase cintiladora. A cristalização induzida é favorecida pela tensão gerada na interface cristal/vidro, devido a uma diferença de volume molar entre essas duas fases, o que permite que o fenômeno da cristalização seja observado em temperturas inferiores à Tg. / Glassy materials with similar properties to those of the bismuth-germanate crystal in the composition of Bi4Ge3O12, a scintillator material with the eulytite structure, are of interest due to their luminescent properties that makes them promising materials to application as optical devices. Glasses from the system GeO2-Bi2O3 (BGO) has also being subjects of numerous studies, by combining a typical glass former oxide (GeO2) with the conditional one intermediate compound (Bi2O3). The presence of these two oxide compounds in the glass composition provides them a unique structural characteristic resulting from the coordination changes of germanium atoms (germanium anomaly phenomenon) and also of the bismuth atoms. In the present work, it was studied the influence of CeO2 addition, commonly known as an oxidant agent, in the physical-chemical properties of the bismuth-germanate glasses up to the system [100-x].[(1-y)GeO2-yBi2O3 ]:xCeO2 (for x = 0.2 or 1 and y = 0.2 or 0.3 mol %), prepared by the melting/molding method. The inhomogeneous darkening of the samples, associated to the thermal reduction of the Bi3+ ions, was avoided by the ceria addition that acts as a local modifier of the glass structure even for concentrations of 0.2 mol %. It was observed, by the first time, the crystallization of the eulytite scintillator phase, induced by the presence of Ag in the surface of the glass in the 99[0.8GeO2- 0.2Bi2O3 ]:0.2CeO2 mol % composition, referred to as 80BGO:0.2Ce, below the glass transition temperature (Tg). The Ag diffusion into the glass is a necessary condition to the crystallization phenomenon since this element can be considered as an effective nucleating agent to the scintillator phase. The crystallization is favored by the tension generated in the crystal/glass interface, due to a difference in molar volume of these two phases, allowing that the crystallization phenomenon be observed at temperatures below Tg.

In HIV/AIDS studies, viral load (the number of copies of HIV-1 RNA) and CD4 cell counts are important biomarkers of the severity of viral infection, disease progression, and treatment evaluation. Recently, joint models, which have the capability on the bias reduction and estimates' efficiency improvement, have been developed to assess the longitudinal process, survival process, and the relationship between them simultaneously. However, the majority of the joint models are based on mean regression, which concentrates only on the mean effect of outcome variable conditional on certain covariates. In fact, in HIV/AIDS research, the mean effect may not always be of interest. Additionally, if obvious outliers or heavy tails exist, mean regression model may lead to non-robust results. Moreover, due to some data features, like left-censoring caused by the limit of detection (LOD), covariates with measurement errors and skewness, analysis of such complicated longitudinal and survival data still poses many challenges. Ignoring these data features may result in biased inference. Compared to the mean regression model, quantile regression (QR) model belongs to a robust model family, which can give a full scan of covariate effect at different quantiles of the response, and may be more robust to extreme values. Also, QR is more flexible, since the distribution of the outcome does not need to be strictly specified as certain parametric assumptions. These advantages make QR be receiving increasing attention in diverse areas. To the best of our knowledge, few study focuses on the QR-based joint models and applies to longitudinal-survival data with multiple features. Thus, in this dissertation research, we firstly developed three QR-based joint models via Bayesian inferential approach, including: (i) QR-based nonlinear mixed-effects joint models for longitudinal-survival data with multiple features; (ii) QR-based partially linear mixed-effects joint models for longitudinal data with multiple features; (iii) QR-based partially linear mixed-effects joint models for longitudinal-survival data with multiple features. The proposed joint models are applied to analyze the Multicenter AIDS Cohort Study (MACS) data. Simulation studies are also implemented to assess the performance of the proposed methods under different scenarios. Although this is a biostatistical methodology study, some interesting clinical findings are also discovered.

Numerical simulations of liquid flow in a micro-channel between two horizontal plates are performed. The channel is infinite in streamwise and spanwise directions and its height is taken as m, which falls within the dimension ranges of microchannels. The Navier-Stokes equations with the addition of Brinkman number (Br) to the energy equation are used as the governing equations and spectral methods based approach is applied to obtain the required accuracy to handle liquid flow in the microchannel. It is known for microchannels that Br combines the effects of conduction and viscous dissipation in liquids and is also a way of comparing the importance of latter relative to former. The present study aims to simulate the unusual behavior of decreasing of Nu with increasing Re in the laminar regime of microchannels and to show that Br can be introduced to explain this unexpected behavior. Consequently, it is seen at the end of the results that secondary effect of the Br is observed for the single-phase convective heat transfer. Therefore, a laminar flow of a liquid in a microchannel shows different characteristics compared to a similar flow in a macrochannel. To observe the differences, three different cases are run over each of a range of Reynolds numbers: one with no axial conduction assumption that corresponds to a case similar to macrochannel flow, another case with axial conduction included in the energy equation to simulate one of the main differences and lastly a case with the inclusion of Br number in the governing equations. A similar study is made for natural convection with the same numerical set-up for the same three cases. Formation of Rayleigh-Benard cells are observed for the critical numbers widely accepted in the literature. The results are compared with each other to see the effects of axial conduction and Br inclusion, in addition to Ra for natural convection.

This research project is concerned with workers’ narratives, specifically those who have been employed in paid work below the national minimum wage in New Zealand. As a graphic designer who has direct experience of exploitation through employment, I am interested in researching the subjective experience of underpaid workers in New Zealand. In doing this I have sought to creatively synthesize experiences into artworks that provide a deeper insight into the impact of underpaid work. Through this investigation I have attempted to contribute to a broader discussion of underpaid work than what is currently provided, through the analysis of statistical data. In undertaking this project I have also been concerned with investigating new potentials in serigraphy (a graphic medium traditionally associated with working-class politics). I have inquired into how it might be used to create a visual ‘voice’ for contemporary workers’ narratives. Accordingly, this project has employed audio recordings of three personal stories. The research has led to the production of a series of serigraphic prints that artistically interpret the journeys and experiences of the participants. These images sit in discourse with looped audio excerpts of their recorded interviews. In this approach, narratives of marginalisation that have often been muted through their presentation as written records, have been re-conceptualised as an artists' images, with which the recordings are in discussion.

This research project is concerned with workers’ narratives, specifically those who have been employed in paid work below the national minimum wage in New Zealand. As a graphic designer who has direct experience of exploitation through employment, I am interested in researching the subjective experience of underpaid workers in New Zealand. In doing this I have sought to creatively synthesize experiences into artworks that provide a deeper insight into the impact of underpaid work. Through this investigation I have attempted to contribute to a broader discussion of underpaid work than what is currently provided, through the analysis of statistical data. In undertaking this project I have also been concerned with investigating new potentials in serigraphy (a graphic medium traditionally associated with working-class politics). I have inquired into how it might be used to create a visual ‘voice’ for contemporary workers’ narratives. Accordingly, this project has employed audio recordings of three personal stories. The research has led to the production of a series of serigraphic prints that artistically interpret the journeys and experiences of the participants. These images sit in discourse with looped audio excerpts of their recorded interviews. In this approach, narratives of marginalisation that have often been muted through their presentation as written records, have been re-conceptualised as an artists' images, with which the recordings are in discussion.

To build sustainable peace, all levels of society need to be involved, from the top governmental authorities (state actors) to the ground civilians (non-state actors). The grassroots level is getting more and more attention and is acknowledged as a crucial part in the peace-building process, despite that the official peace process commonly target the top level. Peace agreements signed by the elite will not be implemented thoroughly in society, unless the population living the conflict will have own agency. This thesis uses South Sudan as a case study, with focus on locally employed INGO workers and their role and agency in moving towards sustainable peace. A literature review of well-known and recent research on the topic peace-building from below, along with interviews with the targeted group was used to establish if the theory can be reflected in practise in this specific context. An inclusive approach with all levels of the society seems to be the best strategy for such a divided context as South Sudan, affected by present and past grievance and with weak governmental structures. The social infrastructures have been partially replaced with (I)NGOs, providing a vast amount of basic services across the country. Due to the high prevalence of humanitarian actors and consequently a high number of national staff, they could be a part of the bottom-up approach. Though there is a consensus of an inclusive bottom-up approach in peace-building, the specific role of locally employed (I)NGO worker is not very well examined in the literature. National staff has clear benefits due to their role as (I)NGO workers such as respect and exposure in combination with their local expertise and network. This can contribute to a broader understanding of the situation - that wisdom should not be wasted and can contribute to them having possibility of having a voice and being a connector in the society. There is however not a clear result if this differs from the influence of other civilians and if it translates directly as a benefit in peace–building. More research is needed to determine the real agency of this group.

Submitted by Izabel Franco (izabel-franco@ufscar.br) on 2016-09-20T19:41:19Z No. of bitstreams: 1 DissFRM.pdf: 737919 bytes, checksum: d358a92b8c741ba87cb93c7c6ccd6fc9 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2016-09-23T14:23:19Z (GMT) No. of bitstreams: 1 DissFRM.pdf: 737919 bytes, checksum: d358a92b8c741ba87cb93c7c6ccd6fc9 (MD5) / Approved for entry into archive by Ronildo Prado (ronisp@ufscar.br) on 2016-09-23T14:23:28Z (GMT) No. of bitstreams: 1 DissFRM.pdf: 737919 bytes, checksum: d358a92b8c741ba87cb93c7c6ccd6fc9 (MD5) / Made available in DSpace on 2016-09-23T14:31:05Z (GMT). No. of bitstreams: 1 DissFRM.pdf: 737919 bytes, checksum: d358a92b8c741ba87cb93c7c6ccd6fc9 (MD5) Previous issue date: 2015-03-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / This study relies on the occupational trajectories of workers engaged in popular ways of trade. As background, we have the capitalist transformations in the latest’s decades, which resulted in economical, technological and cultural changes that affected deeply the position of work as a constructor of identities and social values. It is noticed that the precariousness of the formal work relationships associated to the dissemination of the ideology of entrepreneurship has resulted in the search for occupational and income alternatives that weakened the frontiers between formal and informal. In this scenario, the demarcations amidst legal and illegal also became less evident and significant. This way, we discuss the insertion of agents in informal economical activities – as those exercised by street venders -, trying to escape viewing unemployment or precariousness in the labor market as main reasons to exert those occupations. Taking into consideration the subjectivity of the situations, we try to think over the influence of an entrepreneur reasoning under the subjects conduct. From the recovery of the occupational trajectories of agents involved in different popular trade grades, we seek to understand the worker’s perception about his own occupation and the values attributed to those forms of work in the contemporary world, considering that, even though traditional, these activities have been through reconfigurations of its practice and meaning in front of the new economic and cultural context on which it is presented. / Esta pesquisa se propõe a refletir sobre as trajetórias ocupacionais de trabalhadores engajados em formas de comércio popular. Temos como pano de fundo as transformações capitalistas das últimas décadas, que desencadearam mudanças econômicas, tecnológicas e culturais cujos efeitos impactaram profundamente o trabalho como estruturador de identidades e valores sociais. Observa-se que a precarização das relações formais de trabalho associada à disseminação da ideologia do empreendedorismo têm resultado na busca por alternativas de ocupação e renda que afrouxam as fronteiras entre o formal e o informal. Nesse movimento, as demarcações entre o legal e o ilegal também se tornaram menos evidentes e significativas. Assim, discutimos a inserção dos agentes em atividades econômicas informais – como as exercidas por camelôs e sacoleiros –, tentando escapar da experiência do desemprego ou precariedade do mercado de trabalho como imperativos para o engajamento nessas ocupações. Levando em consideração a dimensão subjetiva das situações, procuramos refletir acerca da influência de um discurso empreendedor sobre a disposição dos sujeitos. A partir da recuperação de trajetórias ocupacionais de agentes envolvidos em diferentes escalas do comércio popular, objetiva-se compreender a percepção do trabalhador sobre sua ocupação e os valores atribuídos a essas formas de trabalho no mundo contemporâneo, considerando que, apesar de tradicionais, essas atividades têm passado por reconfigurações de suas práticas e significados frente ao novo contexto econômico e cultural que se apresenta.